ISSN 1408-7073 RMZ - MATERIALS AND GEOENVIRONMENT PERIODICAL FOR MINING, METALLURGY AND GEOLOGY RMZ - MATERIALI IN GEOOKOLJE REVIJA ZA RUDARSTVO, METALURGIJO IN GEOLOGIJO RMZ-M&G, Vol. 56, No. 3 pp. 254-388 (2009) Ljubljana, September 2009 Historical Rewiev This year University of Ljubljana marks its 90th anniversary. Technical fields were joint in the School of Engineering that included the Geologic and Mining Division while the Metallurgy Division was established in 1939 only. Today the Departments of Geology, Mining and Geotechnology, Materials and Metallurgy are part of the Faculty of Natural Sciences and Engineering, University of Ljubljana. Before War II the members of the Mining Section together with the Association of Yugoslav Mining and Metallurgy Engineers began to publish the summaries of their research and studies in their technical periodical Rudarski zbornik (Mining Proceedings). Three volumes of Rudarski zbornik (1937, 1938 and 1939) were published. The War interrupted the publication and not untill 1952 the first number of the new journal Rudarsko-metalurski zbornik - RMZ (Mining and Metallurgy Quarterly) has been published by the Division of Mining and Metallurgy, University of Ljubljana. Later the journal has been regularly published quarterly by the Departments of Geology, Mining and Geotechnology, Materials and Metallurgy, and the Institute for Mining, Geotech-nology and Environment. On the meeting of the Advisory and the Editorial Board on May 22nd 1998 Rudarsko-metalurski zbornik has been renamed into "RMZ - Materials and Geoenvironment (RMZ -Materiali in Geookolje)" or shortly RMZ - M&G. RMZ - M&G is managed by an international advisory and editorial board and is exchanged with other world-known periodicals. All the papers are reviewed by the corresponding professionals and experts. RMZ - M&G is the only scientific and professional periodical in Slovenia, which is published in the same form nearly 60 years. It incorporates the scientific and professional topics in geology, mining, and geotechnology, in materials and in metallurgy. The wide range of topics inside the geosciences are wellcome to be published in the RMZ -Materials and Geoenvironment. Research results in geology, hydrogeology, mining, geotechnology, materials, metallurgy, natural and antropogenic pollution of environment, biogeochemistry are proposed fields of work which the journal will handle. RMZ - M&G is co-issued and co-financed by the Faculty of Natural Sciences and Engineering Ljubljana, and the Institute for Mining, Geotechnology and Environment Ljubljana. In addition it is financially supported also by the Slovenian Research Agency, Science and Technology of Republic of Slovenia. Editor in chief Table of Contents - Kazalo Original Scientific Papers - Izvirni znanstveni članki Laser cladding in the use effects on nitrided and PVD coated steels used for die-casting using various process parameters and techniques Pojavi pri laserskem navajanju nitriranih in PVD prevlečenih jekel za orodja za tlačno litje z uporabo različnih parametrov in tehnik Bombac, D., Fazarinc, M., Pleterski, M., Tušek, J., Muhič, T. Characterisation of solid airborne particles in urban snow deposits from Ljubljana by means of SEM/EDS Opredelitev trdnih zračnih delcev v snežnem depozitu iz urbanega območja Ljubljane s SEM/EDS Miler, M., Gosar, M. Aspects of structures and depositional environment of sand bodies within tomboy field, offshore western Niger Delta, Nigeria Značilnosti struktur in okolja odlaganja peščenih teles v območju Tomboyja, priobalna delta Zahodnega Nigra, Nigerija Nton, M. E., Adesina, A. D. Mineral Policy in the Era of Sustainable Development: historical context and future content Rudarska politika v času trajnostnega razvoja: zgodovinski kontekst in vsebine prihodnosti Šolar, S. V., Shields, D. J., Miller, M. D. The error estimation in the prediction of ultimate drift of RC columns for performance-based earthquake engineering Ocena napake pri napovedovanju mejne premaknitve AB-stebrov v potresnem inženirstvu Peruš, I., Dolšek, M. 254 266 284 304 322 Preliminary Notes — Predhodne objave Extra machinability modeling Modeliranje povečane obdelovalnosti Kovačič, M., Pšeničnik, M. 338 Environmental labelling of products with type I labels Ekološko označevanje proizvodov z oznakami tipa I Crnobrnja, B., Budak, I., Ilič, M., Hodolič, J. 346 Professional Papers — Strokovni članki Heat Treatment of Cold Formed Steel Forgings 356 Toplotna obdelava hladno preoblikovanih jeklenih odkovkov Kosec, B., Brezigar, M., Kosec, G., Cevnik, G., Bizjak, M. Optimiranje delovanja glavnih ventilatorjev v času mirovanja jame 364 Optimisation of mine ventilators operation in conditions of stagnation the pit Salobir, B. Author's Index, Vol. 56, No. 3 374 Instructions to Authors 376 Template 383 Laser cladding in the use effects on nitrided and PVD coated steels used for die-casting using various process parameters and techniques Pojavi pri laserskem navarjanju nitriranih in PVD prevlečenih jekel za orodja za tlačno litje z uporabo različnih parametrov in tehnik D. Bombač1, *, M. Fazarinc1, M. Pleterski2, J. Tušek2, T. Muhič3 'University of Ljubljana, Faculty of Natural Sciences and Engineering, Aškerčeva cesta 12, SI-1000 Ljubljana, Slovenija 2University of Ljubljana, Faculty of Mechanical Engineering, Aškerčeva cesta 6, SI-1000 Ljubljana, Slovenija 3TKC, d. o. o., Trnovska 8, SI-1000 Ljubljana, Slovenija Corresponding author. E-mail: david.bombac@ntf.uni-lj.si Received: March 30, 2009 Accepted: May 15, 2009 Abstract: Repair welding of die-casting tools is approach to extend life cycle of expensive dies. Issues addressed in this paper are problems emerging from repair welding of surface treated steels e.g. nitriding, oxidizing, hard coating or duplex-treating. Cladding tests were carried out on various gas nitrided and oxidized or hard coated chrome martempered steel used for die tools. Observed welding defects were extensive hot cracking and copious formation of gas pores. For duplex-treated surfaces a procedure with preceding laser remelting and laser welding is proposed. Minimized negative effects of the base and welded material were found. Izvleček: Reparaturno varjenje je postopek za podaljšanje trajnostne dobe dragih orodij za tlačno litje. V članku so obravnavani problemi, ki nastajajo pri reparaturnem varjenju površinsko obdelanih jekel: ni-triranje, oksidiranje, prevlečenje ali zaporedna površinska obdelava z različnimi procesi (na primer nitrirnanje in nato PVD prevlečenje). Preizkusno varjenje je bilo izvedeno na različnih plinsko nitriranih in oksidiranih ali prevlečenih vzorcih iz kromovega maraging jekla za livarska orodja. Zaznane varilne napake so bile znatne razpoke in številne plinske pore. Za dvojno oplemenitene površine je predlagan nov postopek varjenja s predhodnim pretaljevanjem. Ugotovljeno je bilo zmanjšanje negativnih efektov podlage in varilnega materiala. Key words: laser cladding, repair welding, die-casting tool steel, nitrid- ing, oxidizing, PVD coating Ključne besede: lasersko navarjanje, reparaturno varjenje, jekla za orodja za tlačno litje, nitriranje, oksidacija, PVD-prevleke Introduction Parts for automotive industry made from aluminium or plastic are usually casted or moulded. Casting dies are subjected to various complex impact and thermomechanical loads in their working environment. High stresses lead to a plastic deformation of the die during tool's lifetime. Thus, it is required that steels used for casting dies should have some properties such as resistance to high temperatures, thermal deformation, thermal shock during working processes, etc. Depending on a tool application, typical damage and failure mechanisms may differ. A thermal fatigue cracking is the most important life limiting failure mode in the tools for die-casting.[1-4] It is often observed on the tool surface as a network of fine cracks or as individual and clearly pronounced cracks. Formation of thermal fatigue cracks leads to loss of a surface material in form of small fragments. Other common reasons for damage are tension cracks caused by constructional notches, local adherence of a casting alloy and tool i.e. soldering, and steel erosion promoted by the cast molten metal or plastic flow.[5, 6] While moulds for plastic injection moulding are subjected to lower working temperatures their pressure cycles are higher and therefore, mechanical fatigue damage and overload failures might occur. Life time for aluminium casting dies is usually 104 cycles.[7] Increasing demand for reduction of manufacturing costs dew to economical reasons requires the exploration of adaptable and reliable solutions for extending the life time of the dies using nitriding, oxidizing, PVD coatings or various duplex treatments. Further extension of the life time of the dies is achieved with die repairing techniques such is surface welding. Nitrided die casting tools have a lot of advantages i.e. easier separation of a casted part and mould, less frequent cleaning of the die-core system and increase of the service life for up to 50 %.[8] Available reports show that plasma nitriding improves thermal fatigue resistance due to high residual stresses in the diffusion layer and improves its tempering resistance. It is also reported that thermal cracks remain localized in the compound layer.[9] Another surface improvement is oxidation i.e. process that creates a lubricant oxide film to prevent soldering and adhesive wear in high pressure die casting tools, usually performed after nitriding. Further improvements are made using hard coating based on nitrides and carbides of transition metals, e.g. CrN, CrC, TiAlN, TiB2.[10] Deposition of these coatings is made by physical or chemical vapour deposition (PVD or CVD). These coatings further reduce erosion, soldering, and corrosion but lack in improvement of the thermal fatigue resistance of hot working steels in die-casting conditions. None of the above mentioned surface treatments provides an optimum solution for all failure mechanisms,[11] therefore the best choice is a combination of surface improvements designed specifically for each application. inert gas (TIG) welding or laser cladding by wire. Later approach is done by pulsed Nd:YAG laser beam focused at the tool damaged surface while an operator adds a filler wire in the molten pool. Laser repair welding is particularly appreciated due to exact positioning and focalization control of the beam allowing elevated accessibility even in thin and narrow areas that cannot be welded conventionally.[14] Although repair welding is carried out on majority of the tools it is considered critical for improved surfaces due to occurrence of welding defects. Furthermore each surface improvement combination has specific repairing technique, meaning that improvements of repair welding process are necessary. The primary goal of this study was to investigate problems emerging from laser repair welding of damaged improved die surfaces without prior removal of the damaged parts or surfaces by milling or grinding. Researches were conducted by optical and electron microscopy for metallographic analysis and microhardness measurements for hardness profiles of welded structures. Repair welding and refurbishing of dies is performed to remove the traces of heat cracking, surface wear, erosion, and stress cracking, thus significantly increasing the tool life cycle.[12, 13] Repair welding of dies is performed by welding with covered electrodes, tungsten Experimental procedure Repair welds investigated in this paper were performed on a high performance AISI H13 (X40CrMoV5-1; Wr.N 1.2344) chromium-molybdenum-va- Table 1. Parameters of laser repair welding process Pulse shape (cf. Figure 5) General Ramped up Ramped down Code (cf. Figure 5) Set 1 Set 2 Set 3 Set 1 Set 2 Set 3 Set 1 Set 2 Set 3 Energy per pulse [J] 11.2 12.9 14.9 11.1 13.1 13.2 11.4 12.8 14.4 Pulse power [kW] 1.3 1.6 1.7 1.3 1.6 1.7 1.4 1.5 1.7 Pulse duration [ms] 6.5 6.5 6.5 Pulse frequency [Hz] 7 7 7 Spot diameter [mm] 0.6 0.6 0.6 Travel speed [mm/min] 0.55 0.55 0.55 nadium hot-work tool steel. Chemical composition in mass fractions of steel samples was 0.35 % C, 0.03 % Si, 0.5 % Mn, 5 % Cr, 2.36 % Mo, 0.55 % V, and balance Fe. Cut samples were hardened and martempered to hardness of 47 HRC. After heat treating, samples were gas nitrided and oxidized or hard coated with TiN or CrN coatings. Gas nitriding was performed at 520 °C for 6 h in a NH3 atmosphere to a depth of around 80 ^m. Oxidation was executed at 500 °C for 4 h in H2/O2 atmosphere. The thermionic arc ion plating in a BAI 730 M deposition system was used to obtain CrN or TiN PVD coatings. Simulation of repair welding was performed using Nd-YAG laser welder and AISI H13 filler wire with 0.5 mm diameter. Effects of the repair welding process parameters were also investigated. Effects of the various laser pulse shapes and different laser welding techniques e.g. frequencies, forma- tion sites, and types of weld defects in continuous seam welds are considered. To resolve a pulse shaping effects, the pulse shapes applied were: general, ramped-up, and ramped-down. Table 1 presents the laser welding and surface remelting process conditions. Continuous seam welds were used as a means of bead on plate welding on specimens to understand the effects of pulse shaping and the formation characteristics of weld defects. Direct welding without remelting single seam multi seam Surface remelting prior to welding TvDe B single seam multi seam Single seam remelting after welding Figure 1. Researched welding techniques Three types of welding techniques were analyzed in order to improve weldability of improved surfaces. First welding technique designated type A is direct welding without prior surface remelting. Type B involves remelting of whole surface with laser prior to repair welding, where at type C first seam is directly welded and later half of it is remelted and on remelted surface operator deposit next seam. Figure 1 schematically shows all investigated welding techniques. Cataloguing and characterization of welding defects in the welded layer and the heat affected zone (HAZ) for various welding parameters was carried out by metallographic analysis. Samples for metallographic analysis were prepared with standard grinding and polishing procedures and etched with 2 % Nital solution to reveal welds. Weld morphology and microstructure were evaluated using scanning electron microscope (SEM) and optical microscopy. In addition, microhardness profiles of welds were measured with hardness tester. Results and discussion Microstructural analysis of welded nitrided surfaces discloses high concentration of pores. Nature of a laser welding causes abrupt melting and consequent quick solidification. Gases formed during melting therefore stay trapped at the edges of a weld melt pool. High-energy input from laser beam induces dissolution of nitrides in nitrided layer and formation of N2 gas. Figures 2a and 2b depicts a weld porosities induced by trapped gasses. Sample has been welded with a Type A welding technique and ramped-up pulse with Set 3 process parameters. Analyzed was longitudinal section of the weld (cf. Figure 2b) due to higher probability of discovering weld defects in longitudinal sections compared to cross sections. Repair welding of a nitrided and CrN coated surfaces is difficult due to formation of cracks at the edges of the HAZ. Their direction of propagation is from pores to apex of the weld due to release of trapped gases. Figure 3a shows weld cracks emerging from pores in the weld. In Figure 3b cracks alongside weld direction in HAZ zone are shown. Depicted repair welded micrograph was obtained from nitrided and CrN coated sample. Similar defects were present in nitrided and TiN coated welded samples. These types of defectss become apparent only after additional surface treatments and therefore their detection during welding is impossible. Also welding of ni-trided and oxidized surfaces causes emergence of pores where dissolute gasses escape from melted weld pool Figure 3. Porosities in weld of nitrided and CrN coated sample; a) micrograph of cracks formed from pores, b) SEM micrograph of cracks along weld direction in HAZ and surface pore m tmsmm ERilfflfiHR S TiN inclusion Figure 4. Laser welds on duplex-treated surfaces; a) nitrided and TiN-coated surface, b) nitrided and CrN coated surface during cooling. Another type of the repair welding defects obtained were cracks along the seam of a weld (cf. Figure 3b). These defects commence due to tensile and compression stress in weld. Figure 4a depicts traces of TiN coating in the laser weld and porosities at the boundary between the weld and a base material. TiN inclusions from coating in weld could be problematic during grinding and final polishing of weld in die-casting tool. These inclusions have high hardness and can cause increased wear of grinding and polishing tools and consequently loss of shape. Weld micrographs of a nitrided and CrN coated sample did not reveal coating inclusions in the weld. In Figure 4b shows weld of nitrided and CrN coated surface using an inclined beam and type C technique. Repair welding of nitrided and coated samples leads to copious development of gas porosity due to nitrogen release from molten nitrided part of surface or exiting of transitional elements from coatings. Inclusions from coatings in welds also cause problems and are therefore unde-sired. Therefore, in order to reduce gas porosity investigation of a laser remelt-ing treatment before weld deposition was conducted. The results suggest that using the type C welding technique and close observation of the welding process parameters minimizes the porosity rate. Appearance of pores (cf. Figure 4) at a contact of the weld and the base material is undesired. These pores present danger for peel-off of weld and surface treatment. It revealed that manipulation Figure 5. Influence of process parameters, welding technique and pulse shape on porosity rate of weld, with presentation of pulse shapes of laser beam parameters or inclination of the beam leads to reduction of these type defects. Usage of beam inclination causes a tampon region, which makes excessive cracking of treated surface impossible. It is possible to prevent excess nitrogen evaporation with manipulation of welding parameters. Welding parameters are also important for minimizing the effect of transitional elements (e.g. Cr, Ti) exiting coatings, especially at multi-seam welding. Unsuitable process parameters, e.g. too high heat input or too low welding velocity are main cause for cracks in HAZ along the seam of the weld due to thermal expansion. With the correct welding process parameters, it is possible to minimize appearance of welding defects. This paper also investigates influence of the process parameters, welding technique and pulse shape on the porosity rate of the weld. Figure 5 shows results of these influences. Depicted in Figure 5 are also pulse shapes marked with colors. Remelting of surface prior to welding causes smaller porosity rate compared to direct welding of surface treated (i.e. nitrided and oxidized or nitrided and PVD coated) surfaces. Type C welding, where each seam is fractionally remelted, has lowest porosity rate. Furthermore, process parameters of the welder and pulse shape are of high importance. As is shown, ramped-down pulse is superior compared to general or ramped-up one. However, it was noticed appearance of low weld fusion penetration or agglutination of weld material. Pulse energy is also very important as pulse energy increase after some critical value leads to declined porosity density in the weld. On the other hand, increase of pulse power causes cracks alongside weld in HAZ and amassment of cracks in surface treated surfaces. One should chose energy per pulse and pulse power specifically for differently treated surfaces. Figure 6 shows dependences of hardness measured in three depths versus distance from the weld line. Mean hardness value was measured in a horizontal line parallel to the surface for type C welding technique. Depths are designated with letters X for surface layer, Y for middle of the weld and Z for weld apex. Mean hardness in area of weld line are lower for approximately 120 HV01 than in area of prior welding remelt line. This is due to tempering effect caused with heat transfer from welding to prior hardened remelt line. Highest measured hardness in re-melt line zone was between 720 HV01 and 800 HV01. Hardness in weld line was due to tempering effect lower and was between 580 HV01 and 650 HV01 depending on the depth of the measurement. As expected, it was highest in the apex of the weld due to additional alloying from filler wire. ■I MR Welq line Remçlt iine YA -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 Distance /mm Figure 6. Microhardness profile measured in thee depths of the weld Measured hardness of base material was approximately 500 HV01 and although prior remelting and welding on the remelted zone caused tempering effect, this is not sufficient to reach hardness values corresponding to the base material. Consequently, needed is additional tempering of the welds to obtain uniform hardness profile as is known that increased hardness influences on decreased toughness, which is crucial especially in the lower layers of the tools. Also in Figure 6 can be seen that welding defects due to release of nitrogen gas from nitrides are only in remelt zone. Pores formed as gas trapping were filled with filler wire material. Due to weld deposit, materials in that area was once again remelted and solidified, and as consequence welding porosities were removed. This means special attention is needed to obtain deep enough heat affected zone only to ensure removal of defects and porosities originated from gases in nitrided zone. Conclusions From the investigations conducted in this paper following conclusions can be drawn. • Repair welding of the nitrided samples resulted in the formation of copious gas pores due to nitrogen release during weld metal solidification. Also cracks starting from these voids were detected. • In PVD coated samples extensive cracking was observed after repair welding tests. • Special attention should be paid to the first surfacing weld adjacent to the surface. Lower power laser beams and the ramped-up pulse shape should be used in order to reduce the level of surface cracking that may subsequently produce peeling-off of the tool surface at duplex-treated samples. The lowest density of porosity is obtained with the ramped-down shape of a laser pulse and a sufficiently high energy permitting complete remelting of the nitrided layer. A combination of welding and preliminary remelting i.e. type B, however, reduces the occurrence of defects, e.g. inclusions and pores, in the surfaced layer, yet this does not provide optimum results since, due to melt spatter, nitride inclusions will persist at the surface and thus pass on to the surfaced layer. The occurrence of inclusions, i.e. rests of melted PVD claddings, can be reduced by using "Leading power spike", which will produce evaporation of the cladding. Welds made with type C welding technique i.e. simultaneous remelt-ing of welded seams, in combination with a falling pulse resulted in lowest density of welding defects. Acknowledgements The authors of this paper would like to thank prof. dr. Ladislav Kosec (University of Ljubljana, NTF, Department of Materials and Metallurgy) and dr. Peter Panjan (Jožef Stefan Institute, Slovenia) for their assistance. References [i] [2] [3] [4] [5] [6] [7] [8] Davis, J. R. (Ed.), ASM Speciality Handbook, Tools materials, ASM International, Materials park, OH, 1995, 251. Allsop, D. F., Kennedy, D. (1983): Pressure Diecasting; The Technology of the Casting and the Die: Part 2, Per-gamon Press, Oxford. Danzer, R., Sturm, F., Schindler, A., Zleppnig, W. (1983): Thermal Fatigue cracks in pressure die casting dies, Gisserei-Praxies 19/20, 287. Venkatesan, K., Shivpuri, R. (1995): An investigation of the effect of process parameters on the washout in die casting dies, North American Die Casting Association, Indianapolis, 361. Persson, A., Hogmark, S., Bergstorm, J. (2005): Surf. Coat. Technol. 191 (2-3), p. 216. Ried, P., Moore, J., Lin, J., Carrera, s. (2005): Die Cast Eng. 49 (5), p. 40. sun, Y., sunada, H., Tsujii, N. (2001): Crack Repair of Hot Work Tool Steel by Laser Melt Processing. ISIJ International; Vol. 41, No. 9, 1006-1009. Panjan, P., Cekada, M., Kirn, R., sokovic, M. (2004): Improvement of [9] [10] [11] [12] die-casting tools with duplex treatment, Surface and Coatings Technology 180-181, 561-565. Spies, H. J., Hoeck, K., Broszeit, E., Matthews, B., Herr, W. (1993): Surface and Coatings Technology; Vol. 60, p. 441. Knotek, O., Loffer, F., Bosserhoff, B. (1993): Surface and Coatings Technology 62, 630. Wang, Y. (1997): A study of PVD coatings and die materials for extended die-casting die life, Surface and Coatings Technology, 94-95, 60-63. Vedani, M., Previtali, B., Vimercati, G. M., Sanvito, A., Somaschini, G. (2007): Problems in laser repair-welding a surface-treated tool steel. Surface and Coatings Technology, 201, 8, 4518-4525. Muhic, T., Tusek, J., Pleterski, M., Bombac, D. (2009): Problems in repair-welding of duplex-treated tool steels, Metalurgija (Metallurgy), 48, 1, 39-42. [14] Ernst, G., Luftenegger, A., Ebner, R. (1999): Proceedings of the Fifth International Conference on Tooling (F. Jeglitsch, R. Ebner, H. Leitner; eds.), Leoben. [13] Characterisation of solid airborne particles in urban snow deposits from Ljubljana by means of SEM/EDS Opredelitev trdnih zračnih delcev v snežnem depozitu iz urbanega območja Ljubljane s SEM/EDS Miloš Miler1, *, Mateja Gosar1 Geological Survey of Slovenia, Dimičeva ulica 14, SI-1000 Ljubljana, Slovenia Corresponding author. E-mail: milos.miler@geo-zs.si Received: April 20, 2009 Accepted: July 10, 2009 Abstract: The main objective of this study was to identify and characterise solid airborne particles deposited in snow of the Ljubljana urban area over a period of 6 days, according to their morphology and chemical composition and to assess their source and genesis by means of scanning electron microscope coupled with energy dispersive X-ray spectrometer (SEM/EDS). This method enables the characterisation of submicroscopic (crystalline and amorphous) particles, present in very small quantities. Two snow samples were collected and analysed. Spherical particles, irregularly shaped fragments and agglomerates were identified according to their morphology. Geogenic and technogenic sources were assessed by considering their chemical composition and morphology. Geogenic particles are represented mostly by irregular mineral fragments of quartz, zircon and clay minerals. Technogenic particles are mostly spherically shaped carbonaceous particles, originating from combustion of coal or liquid fuel and spherical heavy metal-bearing particles, emanating from high-temperature industrial combustion and steel-melting processes. Irregular technogenic particles emanate mostly from incomplete coal combustion and road traffic emissions. Comparison of treated samples showed no significant differences in particles according to their origin. It can be concluded that the sampling location had no important influence on the distribution of particles by their origin. Izvleček: Cilj predstavljene študije je bil prepoznati in opredeliti trdne zračne delce, ki so bili v šestih dneh odloženi v snegu na urbanem območju Ljubljane. Opredelili smo jih glede na njihovo obliko in kemijsko sestavo ter ocenili njihov izvor in nastanek z metodo vrstičnega elektronskega mikroskopa z energijsko disperzijskim spektrometrom rentgenskih žarkov (SEM/EDS). Ta metoda omogoča opredelitev submikroskopskih (kristalnih in amorfnih) delcev, ki so v vzorcih v zelo majhnih količinah. Odvzeli in analizirali smo dva vzorca snega. Po obliki smo delce razdelili v sferične, odlomke nepravilnih oblik in aglomerate. Glede na kemijsko sestavo in obliko smo ločili delce geogenega in tehnogenega izvora. Geogeni delci so večinoma nepravilni mineralni odlomki kremena, cirkona in glinenih mineralov. Med tehnogenimi delci prevladujejo votli sferič-ni delci, ki vsebujejo večinoma ogljik in so nastali pri izgorevanju premoga ali tekočih goriv, in težke kovine vsebujoči sferični delci, ki so nastali pri visokotemperaturnih procesih industrijskega sežiga in taljenja jekla. Tehnogeni delci nepravilnih oblik nastajajo večinoma pri nepopolnem izgorevanju premoga in prometnih emisijah. Primerjava obravnavanih vzorcev ni pokazala razlik v izvoru trdnih delcev. Sklepamo lahko, da na sestavo trdnih zračnih delcev v vzorcih lokacija vzorčenja ni imela pomembnega vpliva. Key words: solid airborne particles, snow deposit, Ljubljana urban area, source apportionment, SEM/EDS Ključne besede: trdni zračni delci, snežni depozit, urbano območje Ljubljane, določitev izvora, SEM/EDS Introduction The combination of the scanning electron microscope and energy dispersive spectrometer (SEM/EDS) is a well-established analytical method across different fields of geology. It has also proved to be a very useful method world-wide in environmental geochemistry for the characterisation of particles in different environmental media. Numerous studies of solid aerosol particles and urban snow deposits attested the usefulness of SEM/EDS in terms of particle characterisation and source apportionment (Aragon et al., 2000; Sokol et al., 2002; Kemppain-en et al., 2003; Trimbacher & Weiss, 2004; umbria et al., 2004; Bernabe et al., 2005; Tasic et al., 2006; Choel et al., 2007). This method supplements other analytical methods, used in min- eralogical and geochemical studies of environmental media, such as optical microscopy, X-ray diffraction and geochemical methods (ICP-MS, AAS etc.). The SEM/EDS also enables characterisation of particles, which are smaller than the resolution of an optical microscope, whose quantity is too small to be analyzed by conventional geochemical methods and when crystal structure of particles is ill-developed or amorphous and cannot be identified using X-ray diffraction. Thus, the SEM/EDS was a method of choice for identification of solid airborne particles in snow deposit from Ljubljana urban area and for the assessment of their qualitative chemical composition. Solid airborne particles are present in all environmental media, reaching from snow to stream sediments, as a consequence of transport processes in the Earth's atmosphere and hydrosphere (Neinavaie et al., 2000). Due to erosion processes and the omnipresent geological and pedological substrata, the sources of natural mineral airborne particles are heterogeneous and well dispersed in all environmental compartments (Neinavaie et al., 2000). Compared to anthropogenic (techno-genic) point sources, natural (geogenic) sources are less significant and usually represent a natural background. Solid airborne particles can be very reactive and toxic to living organisms, due to their chemical composition and large specific surface area available for interactions. For this reason it is essential to assess their chemical composition, morphology, size and source area. Materials and methods Snow is a natural collector and an ideal medium for observation of atmospheric constituents, which have been dry or wet deposited and are mostly well preserved in the snow (Schöner et al., 1993). Solid airborne particles in urban snow deposits are solid particles of different sizes that have been transported and deposited in the snow exclusively by air in the period between the last snowfall and the time of snow sampling. Sources of larger particles are usually located in the vicinity of sampling points; smaller particles, however, can travel between several kilometres and several tens of kilometres in the atmosphere. The average travelling distance of a particle with a diameter of 10 p,m, emitted from a source 20 m above the ground, amounts to 10 km. Particles, emitted from a 100 m high source can travel as far as 60 km (Guth-mann, 1958; Neinavaie et al., 2000). The content of solid airborne particles in the snow is relatively low, which is why snow samples are often prone to contamination (Telmer et al., 2004). Two snow samples were taken at two sampling points in the urban area of Ljubljana. The first sampling point was situated at the sports ground between the Faculty of Economics and the Chamber of Commerce and Industry of Slovenia, 250 m west of Dunajska cesta (Dunajska street) (sample SV-1; Y = 5 462 825, X = 5 103 317). The second sampling point was placed in the park between Dunajska cesta and the Chamber of Commerce and Industry of Slovenia, 13 m west of Dunajska cesta (Dunajska street) (sample SV-2; Y = 5 462 561, X = 5 103 235). Snow samples were collected from a surface of 1 m2 area and a depth of 1 cm, approximately 6 days after the last snowfall (20th of January 2009). Snow samples were melted at room temperature in covered glass containers and filtered through an analytical white ribbon filter paper. Filter residue was dried at 50 °C, mounted on a carbon tape and sputter-coated with a thin layer of gold. Analysis was carried out in high vacuum mode using a scanning electron microscope JEOL JSM 6490LV, coupled with an energy dispersive spectrometer Oxford INCA Energy at accelerating voltage 20 kV and working distance 10 mm. Particles were observed in BSE (backscattered electron) mode, which allows their identification by relative elemental composition (atomic number). Qualitative chemical composition of particles was measured using EDS point X-ray microanalysis with acquisition time 10 s to 30 s. All scanning electron microscopy and energy dispersive spectrometry investigations were performed in our laboratory at Geological Survey of Slovenia. Results and discussion Solid airborne particles in both samples of snow deposit were successfully identified, characterised according to their morphology and elemental composition and allocated to different source categories using the SEM/EDS method. Spherical particles, irregularly shaped fragments and agglomerates were recognised according to their morphology. Particles were classified as geogenic and technogenic, considering their genesis (Table 1). Geogenic particles Particles of geogenic origin are mineral phases, resulting from the weathering of bedrock and erosion of soil and stream sediments (Neinavaie et al., 2000). The size of analysed solid airborne particles of geogenic origin ranges from 12 p,m to 320 p,m, averaging 86.2 p,m (median: 70 p,m). Morphologically, geogenic particles are mostly irregularly shaped sharp-edged fragments of mechanically and chemically resistant rock-forming minerals (zircon, quartz, feldspars etc.). Spherically shaped particles (some clay minerals) are also present but in smaller quantities. Table 1. Allocation of solid airborne particles in urban snow deposits according to their source Geogenic Technogenic zircon fragments (Figure 1) combustion products: barite (also technogenic) low-temperature domestic combustion: hollow spherical particles (less porous) pyrite (also technogenic) irregularly shaped soot particles amphiboles irregularly shaped coal residues (coke) (Figure 2) pyroxenes high-temperature industrial combustion: (spherical) quartz (Figure 2) coal and liquid fuel combustion: K-feldspars hollow spherical particles (porous) (Figure 3) plagioclase Ca-ferrites (Figure 4) (Ca, Al)-silicates clay minerals steel-melting and processing: carbonates (Cr, Ni, Fe)-oxides (Cr, Fe)-oxides (Figure 5) (Ca, Fe)-silicates (Figure 6) road traffic: exhaust soot tyre fragments steel fragments Pyrite and barite both occur as geogen-ic and technogenic mineral phases. The origin of geogenic pyrite and barite is most probably the weathering of bedrock in the surroundings of Ljubljana. Technogenic pyrite probably derives from inorganic mineral constituents or inclusions in parent raw coal dust or occurs as non-combustible residue in ashes produced in coal combustion (KopcEWicz & KopcEWicz, 2001; Parish & Wright, 1994). Figure 1. Geogenic zircon fragment Technogenic barite appears as one of the basic constituents of inorganic colouring pigments (Trimbacher & Neina-vaie, 2002) or as a secondary mineral phase, formed by chemical reaction of barium ions with sulphate ions, arising from high-temperature industrial coal combustion. Technogenic barite also occurs in the form of inclusions in ir- regularly shaped carbonaceous particles of coal residue (coke) (Trimbacher & Neinavaie, 2002). Technogenic particles The diameter of technogenic particles ranges from 2.5 pm to 700 pm, averaging 50 pm (median: 37.5 pm). Preva- 0 2 4 Full Scale 15671 cts Cursor: 0.000 Situ OAlf FeAui Spectrum 2 0 2 4 Full Scale 1582 cts Cursor; 0 000 FeFe Au AuAu Au Au 10 12 Figure 2. Geogenic quartz fragment (sp. 1 - spectrum 1) and presumably coal residue (coke) (sp. 2 - spectrum 2) lent particle types in both samples are irregularly shaped carbonaceous tech-nogenic particles and hollow spherical technogenic particles, as anticipated. Irregularly shaped technogenic carbonaceous particles were interpreted as coke, originating from incomplete coal combustion, and consisting mostly of carbon, sulphur and small contents of silicon, iron, calcium and magnesium. They often contain inclusions of mineral phases such as quartz, barite and pyrite. Hollow particles have been formed during the combustion of coal (Flagan & Seinfeld, 1988) or liquid fuel (fuel oil) (Umbria et al., 2004, Massei et al., 2007). Less porous hollow spherical particles were formed during low-temperature (700-750 °C) incomplete combustion, while more porous and brittle hollow spherical particles were most probably formed during high-temperature complete combustion of coal and liquid fuel. The main constituents of these particles are carbon, sulphur and chlorine while contents of silicon, iron, calcium and magnesium depend on fuel type and manner of combustion. The hollow spherical shape is a result of expulsion of gaseous or liquid materials from the particle interior, due to an increase in internal pressure or decrease in external pressure (Umbria et al., 2004), which is a consequence of abrupt changes in temperature during combustion processes. Spherical particles, emanating from high-temperature industrial combustion, are mostly characterised by massive spherical shape resulting from melting processes that occur during their formation (Umbria et al., 2004; Tasic et al., 2006). Spherical particles, consisting basically of calcium and iron, are Ca-ferrites, which are mineral phases of techno-genic origin, formed during high-temperature industrial coal combustion (1400-1500 °C) and can be used as index minerals or indicators for industrial high-temperature processes (Neinavaie et al., 2000). Ca-ferrites are typical of coal-fired heating stations and thermal power plants emissions (Neinavaie et al., 2000; Sokol et al., 2002). Besides calcium and iron Ca-ferrites often contain trace contents of manganese, titanium, copper and zinc. The elemental composition of Ca-ferrites is strongly dependent upon the composition of inorganic mineral constituents in coal and different coal burning methods (Umbria et al., 2004). Considering the relatively wide range in size of analysed particles, it may be concluded that they most probably originate from local thermal power plants. 0 2 4 6 6 10 12 14 Full Scale 7760 cts Cursor: 0.000 Figure 3. Porous hollow spherical particle (high-temperature coal and liquid fuel combustion) More unusual and unexpected is the fairly high content of spherical particles, comprising compounds of iron and heavy metals, such as chromium, nickel and vanadium in variable ratios. Spherical iron oxides sometimes occur in the form of the technogenic minerals goethite, hematite and magnetite. Particle morphology (spherical shape, dendritic and skeletal crystals in glassy matrix) suggests that they were formed during the melting of steel at very high temperatures, followed by rapid cooling (Aragon et al., 2000). According to their chemical composition these particles were most likely formed in 0 2 4 6 8 10 12 14 Full Scale 737 cts Cursor: 0.000 Figure 4. Spherical particle of Ca-ferrite (high-temperature industrial coal combustion) high-temperature steel production processes or during re-melting and refining of scrap steel, containing the aforementioned heavy metals as alloy components (Seames, 2003; Zhang et al., 2005; Choel et al., 2007). Cr-Ni-V-Fe compounds are common components of different steel grades (http://www. litostroj.com/files/Materials.xls; Kaker & Glavar, 2005). In some cases, spherically shaped (Cr, Fe)-oxides contain small amounts of manganese and copper, while sharp-edged (Cr, Fe)-oxides (also chromite) often contain titanium, which replaces iron ions in the (Cr, Fe)-oxide crystal lattice. Spherical 0 2 4 6 8 10 12 14 Full Scale 2338 cts Cursor: 0.000 Figure 5. Spherical particle of (Cr, Fe)-oxide with V (high-temperature steel-melting processes) (Ca, Fe)-silicates are commonly characterised by well-developed euhedral crystals of Fe-oxides (magnetite) in the glassy matrix of (Ca, Fe)-silicates (Figure 6). The euhedral form of Fe-oxide crystals suggests that they were first to crystallise from the melt, followed by (Ca, Fe)-silicates. There are no steelworks facilities in the surroundings of Ljubljana. Two possible explanations of origin of heavy metal-bearing spherical particles or combination of both are given: • The heavy metal-bearing spherical particles were formed during the melting and casting of steel in local steel castings production. This explanation is supported by the relatively high content of these particles in both samples and wide range in their size, ranging from 2.5 p,m to 98 p,m (averaging 35 p,m). • Particles emanate from a more remote source. However, it needs to be considered that a particle of 10 p,m in diameter can travel over a distance of 60 km, if emitted from a source located 100 m above the ground level (Guthmann, 1958; Neinavaie et al., 2000). In our case particles have an average diameter of 35 p,m (less than 11 % of particles are smaller than 10 ^m) and it can be assumed that their source is either closer than 60 km or higher than 100 m. Characteristics of samples SV-1 and SV-2 and their comparison Sample SV-1 Irregularly shaped and sharp-edged carbonaceous technogenic particles, interpreted as coke, and geogenic particles, such as quartz, zircon and clay minerals, are the most abundant particle types among analysed particles in sample SV-1. Heavy metal-bearing spherical tech-nogenic particles, formed during high-temperature industrial combustion, are present in lesser quantities. The size of geogenic particles ranges from 12 p,m to 320 ^m, averaging 77.8 p,m (median: 54.5 p,m). The largest particles belong to grains of quartz and the smallest to zircon fragments, which are also the most frequently occurring particles of geogenic origin. The measured size of technogenic particles ranges from 5 p,m to 181 ^m, averaging 44.8 p,m (median: 37 p,m). The largest technogenic particles originate from low-temperature combustion processes (hollow spherical particles, coke, soot). The smallest are heavy metal-bearing particles, originating from high-temperature industrial combustion and steel-melting processes ((Cr, Fe)-oxides, (Cr, Ni, Fe)-oxides, Ca-ferrites and Fe-oxides). Sample SV-2 Analysed particles are represented mostly by irregularly shaped flat carbonaceous particles, interpreted as coke, and geogenic particles (quartz, zircon, clay minerals). Heavy metal-bearing technogenic particles are present in smaller quantities. The size of the geogenic particles ranges from 24 p,m to 173 p,m, averaging 99 p,m (median: 115 p,m). Grains of Al-silicates and quartz are the largest and the most abundant among geogenic particles, while zircon fragments are the smallest. The techno-genic particles range in size from 2.5 p,m to 700 ^m, averaging 57 p,m (median: 38 p,m). The largest technogenic particles arise from low-temperature 0 2 4 6 8 10 12 1 + Full Scale 392 cts Cursor: 0.000 0 2 4 6 8 10 12 14 Full Scale 765 cts Cursor: 0.000 Figure 6. Particle of (Ca, Fe)-silicate with euhedral crystals of Fe-oxide (high-temperature steel-melting processes) combustion processes (hollow spherical particles, coke, soot). The smallest in diameter are spherical Ca-ferrites, (Ca, Fe)-silicates and heavy metal-bearing (Cr, Ni, Fe)-oxides, Fe-oxides and (Cr, Fe)-oxides that are also the most numerous among heavy metal-bearing particles. Great differences in the ratio between geogenic and technogenic particles in both samples were expected. Higher contents of technogenic particles, originating from road traffic emissions, should be present in sample SV-2, collected at sampling point close to the main road, compared to sample SV-1. But this was not the case. Comparison of both samples showed no significant differences in content of particles considering their origin. Figure 7 shows that, although absolute average particle size in the sample SV-1 differs from that in the sample SV-2, the trend of average particle size is similar in both samples. Technogenic particles from high-temperature industrial combustion and melting processes are the smallest particle types in both samples, while the largest belong to the hollow spherical and irregularly shaped carbonaceous technogenic particles, emanating from high-temperature coal and liquid fuel combustion and low-temperature domestic combustion, respectively. Figure 7. Comparison of average size of geogenic and technogenic particles in samples SV-1 and SV-2 Conclusions Using the SEM/EDS method, solid airborne particles in snow deposit from the Ljubljana urban area were successfully characterised and classified according to their genesis, morphology and elemental composition. Geogenic particles are mostly sharp-edged, while technogenic particles are spherically and irregularly shaped. It was established that irregularly shaped technogenic particles, interpreted as coke and originating from incomplete coal combustion and sharp-edged geogenic mineral particles, such as quartz, zircon and clay minerals, are the prevailing solid airborne particles in Ljubljana urban snow deposits. Spherical technogenic particles, resulting from high-temperature combustion processes, are present in smaller quantities. Considering relatively wide size range of analysed technogenic particles, formed during high-temperature industrial combustion and melting processes, it may be concluded that their source is in close vicinity of sampling points. Comparison of both samples, SV-1 and SV-2, showed no significant differences in particles considering their origin and chemical composition. 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[21] Zhang, C., Yao, Q., Sun, J. (2005): Characteristics of particulate matter from emissions of four typical coal-fired power plants in China. Fuel Processing Technology; Vol. 86, pp. 757-768. Aspects of structures and depositional environment of sand bodies within tomboy field, offshore western Niger Delta, Nigeria Značilnosti struktur in okolja odlaganja peščenega materiala v območju Tomboyja, priobalna delta Zahodnega Nigra, Nigerija M. E. Nton1- *, A. D. Adesina1 University of Ibadan, Department of Geology, Ibadan, Nigeria Corresponding author. E-mail: ntonme@yahoo.com Received: April 10, 2009 Accepted: May 11, 2009 Abstract: Sand bodies deposited across normal growth faults and associated rollover anticlines are critical reservoirs for the accumulation of oil and gas. This paper addresses aspects of structures and depositional environments of some sand bodies within the Tomboy field, offshore western Niger Delta. Structural interpretation was undertaken to identify and assign faults found in the 3-D seismic volume. Time and depth structure maps in combination with well logs were used to produce for five horizons, namely: H1 to H5 and identify the depositional environments respectively. Two major growth faults (F4 and F7 which are normal, listric concave in nature), three antithetic (F1, F3 and F6) and two synthetic faults (F2 and F5) were identified. Structural closures identified as rollover anticlines, and displayed on the time/depth structure maps; suggest probable hydrocarbon accumulation at the downthrown side of the fault F4. Point bars, distributary channel and mouth bars, barrier island and tidal channels are the depositional environments. This study shows that the Tomboy field is made up of sand bodies deposited in different environments across normal, growth faults and associated rollover anticlinal structures. Izvleček: Peščen material, odložen ob sinsedimentnih normalnih prelomih in z njimi povezanimi naleglimi antiklinalami, so pomembna nahajališča nafte in plina. Članek se ukvarja z značilnostmi struk- tur in okolja odlaganja peščenega materiala v območju Tomboyja v priobalni delti Zahodnega Nigra. S strukturno interpretacijo smo ugotovili prelome iz 3-D seizmičnih podatkov. Na podlagi strukturnih kart v časovni in prostorski domeni ter z elektrokarotažami smo izdvojili pet stratigrafskih horizontov in ugotovili njihova sedimen-tacijska okolja. Določili smo dva večja sinsedimentna preloma (F4 in F7, ki sta normalna in listrično konkavna), tri antitetične (F1, F3 in F6) in dva sintetična preloma (F2 in F5). Strukturne pasti v naleglih antiklinalah, ki smo jih identificirali na strukturnih kartah, nakazujejo možnost akumulacije ogljikovodikov v spuščenem krilu preloma F4. Sedi-mentacijska okolja so meandrske sipine, razvodni kanali ter sipine v ustju, pregradni otoki in plimski kanali. Študija je pokazala, da polje Tomboy sestavljajo peščenjaki, ki so se odložili v različnih sedimentacijskih okoljih ob sinsedimentnih normalnih prelomih in z njimi povezanimi strukturami naleglih antiklinal. Key words: structures, depositional environment, Niger Delta Ključne besede: strukture, sedimentacijska okolja, delta reke Niger Introduction The Niger Delta Basin to date is the most prolific and economic sedimentary Basin in Nigeria. It is an excellent petroleum province, ranked by the U. S. Geological Survey World Energy Assessment as the twelfth richest in petroleum resources, with 2.2 % of the world's discovered oil and 1.4 % of the world's discovered gas (Klett et al., 1997; Petroconsultants, Inc. 1996). By virtue of the size and volume of petroleum accumulation discovered in this basin, various exploration strategies have been devised to recover the enormous oil and gas deposits. These comprise onshore exploration of oil and gas as well as on continental shelf, and in deep offshore. Sand bodies were deposited across normal, growth faults and associated rollover anticlines and represent important reservoirs for the accumulation of oil and gas, especially in the Niger Delta. It has been documented in the Niger Delta that growth faults and rollover anticline structures serve as traps for petroleum accumulation (Merki, 1972; Orife & Avbovbo, 1982). In this study, GeoGraphix software combined with well logs and 3-D seismic volume were used to show how structural deformation and depositional Figure 1. Location map of the study area (Modified from Owoyemi, 2004 and Microsoft Encarta, 2006) Figure 2. Seismic Survey Base Map of the Tomboy Field showing the location of the four studied wells and seismic section environment can influence the accumulation of oil and gas. These can assist in well placements and narrow down areas for detailed exploration and production. Study area and regional geology setting The area of study, Tomboy Field, is located within the western margin of offshore Niger Delta (Figure 1) and belongs to Chevron Texaco Limited concession. The seismic base map of the area originates from latitude 4.0 oN and longitude 4.5 oE, covering an area of 55 km2 (Figure 2). The in-lines and cross-lines are in the ranges of 5800 to 6200 and 1480 to 1700 respectively and with a spacing of 25 m between lines. The four wells, namely BLG1, BLG2, BLG5 and BLG6, utilized for this study were drilled to the depths of 13,019.00 ft (3,945.15 m), 12,996.0 ft (3,938.18 m), 11,541.50 ft (3,497.42 m) and 11,674.50 ft (3,537.72 m) respectively. These four wells have composite well logs which include gamma ray; resistivity, sonic, and neutron/density logs. The 3-Di-mensional seismic volume is in SEG-Y format, whereas the well log data are in LAS format. The Tomboy field is located within the geological setting of the Niger Delta where clastic wedges are deposited along the failed arm of a triple junc- tion system. Originally, the Delta was formed during the breakup of the South American and African plates during the late Jurassic (Burke, 1972; Whiteman, 1982). The two rift arms that followed the southwestern and southeastern coast of Nigeria and Cameroon developed into the passive continental margin of West Africa, whereas the third failed arm formed the Benue Trough which is located under the Gulf of Guinea, offshore Nigeria. After an early history of rift filling in the late Mesozoic, the clastic wedge steadily prograded into the Gulf of Guinea during the Tertiary as drainage expanded into the African Craton with consequent subsidence of the passive margin. These upward-coarsening strata, offlap-ping this continental margin, have been divided into three diachronous lith-ostratigraphic units, namely the Akata, Agbada, and Benin Formations (Figure 3; Short & Stauble, 1967; Doust & Omatsola, 1990). The Akata Formation is the oldest of the units and composed mainly of marine shales which range in age from Eocene to Recent. The Agbada Formation overlies the Akata Formation and comprises mainly alternating deltaic sandstones with shale. It age ranges form Eocene to Recent. The Benin Formation is the youngest in the lithostratigraphic succession, and comprises sandstone, grits, claystone and streaks of lignite. Its age ranges from Oligocene to Recent. The Niger Delta is subtly disturbed at the surface but the subsurface is affected by large scale synsedimentary features such as growth faults, rollover anticlines and diapirs (Doust & Omat-sola, 1990; Stacher, 1995). The structural style, both on regional and on the field scale, can be explained on the basis of influence of the ratio of sedimentation to subsidence rates. The dif- SOUTHWEST NORTHEAST I <>'|I ol noaiOflil tiurKSIJor ferent types of structures are namely, simple non-faulted anticline rollover structures, faulted rollover anticline with multiple growth faults, or anticline faults and complicated collapse crest structures (Evamy et al., 1978). Others are sub-parallel growth fault (k-block structures) and structural closures along the back of major growth faults (Figure 4). Continental-margin collapse structures exert control on depositional and strati-graphic patterns within the Niger Delta Figure 3. Stratigraphic column showing the three formations of the Niger Delta (After Shannon and Naylor (1989) and Doust and Omatsola 1990) Figure 4. Examples of Niger Delta oil field structures and associated trap types (After Doust and Omatsola, 1990 and Stacher, 1995) Figure 5. Schematic diagram showing the development of successive growth-fault-bounded depobelts during progradation of the unstable Niger Delta clastic wedge (After Knox and Omatsola, 1989) clastic wedge (Figure 4). At the largest scale, these structures extend laterally along depositional strike across nearly the entire Niger Delta (hundreds of kilometers), defining ''mega structures'' of Evamy et al. (1978) and associated ''depobelts'' that are tens of kilometers wide perpendicular to the shoreline (Knox & Omatsola, 1989; Doust & Omatsola, 1990). Six regional depobelts were deposited during the 25 Ma - from Early Miocene to present (Figures 5 and 6). Depobelts tend to become finer-grained laterally away from areas of most rapid delta progradation and basinward away from areas of most rapid growth fault development (Doust & Omatsola, 1990). Smaller-scale faults and associated structural deformation accommodating collapse of depobelts tend to be more complex near the progradational axis of the delta than at its margins. This pattern of deposition continues still today, with extensional development of the growth faults on the modern shelf and slope, and compressional uplift near the toe of the slope (Armentrout et al., 2000; Hooper et al., 2002). Materials and methods GeoGraphix software was combined with well logs and seismic data using laid down procedures as shown in Figure 7. The top and base of the Agbada Formation were determined using the reflection characteristics of the 3-D seismic volume, stratigraphic indicators and the nature of the gamma ray curves that characterize this interval. The lithologies penetrated by the studied wells were determined by setting the cut-off point at 65 API on the gamma ray logs. Major and minor faults were identified, traced and assigned using the GeoGraphix software. The faults which were picked at an interval of 10 on the in-lines section were subsequently reflected on the cross-lines sections. IKMD SCHEMATIC PLAÏ WAP _____i Figure 6. Map of Niger Delta showing the depobelts (After Weber, 1971) Five horizons were defined on the top of sand bodies from the gamma ray and resistivity log sections (Figure 8). These horizons were later correlated in the 3-D seismic volume in order to produce time and depth structure map of the horizons. After correlation, time and depth structure maps were produced using the GeoAtlas module of the GeoGrapix software. The time-depth relationship was determined by plotting the checkshot data available for the well BLG1 using Microsoft Excel. Interpretation of depositional envi- ronments is based on the combination of the gamma ray log with resistivity log signatures which were corroborated by Schlumberger (1985) and Busch (1975) charts (Figures 9 and 10). Results and discussions Seismic Record and lithologie identification of the field Reflection characteristics between 0 s and about 1.35 s two-way travel time observed from the seismic record show Figure 7. Work flowchart of study Figure 8. Cross section of the four wells showing horizons delineated on the top of sand bodies pomnm . f f nnpimij Bj«BBirn»s MMR MS s ! mmum j ■EACH tnjKE EiACH DISTRIBUTARrOUUNEL ( BARRIERFOOT ^ 1 OUTER IIIER HSTfllEUTAAV MOUTH BAR K ™L TIDAL CMEL f^T { < Figure 9. Recognition of depositional environments using gamma ray logs from deltaic reservoirs (After: Schlumberger, 1985) Figure 10. Assortment of gamma ray and resistivity log shapes suggestive of deposi-tional environment (After: Busch, 1975) a characteristics low amplitude, parallel, and discontinuous reflection patterns of the field (Figure 11). Based on regional studies and the uniformly blocky, low-value gamma-ray patterns observed within this interval, this portion can be inferred as the Benin Formation (Weber, 1971; Orife & Avbovbo, 1982; Doust & Omatsola 1990; Died- jomahor et al., 2002; Larue & Legare, 2004; Obiora, 2006). The reflection interval between 1.35 s to 2.8 s two-way travel time, consist of parallel and high amplitude reflections that is diagnostic of Agbada Formation (Figure 11). Below the 2.8 s two way travel time, are chaotic, low amplitude reflections interpreted as the Akata Formation. _i_i_i_i_i__i_i_i__i_i_i_i_i_i_1_i_i_i_i_i_i_i_ . Figure 11. Seismic section showing the four wells and their respective gamma ray and resistivity logs, stratigraphy, faults, horizons and seismic reflection characteristics of the study area. The four wells located within the field, penetrated two different lithological zones. The first zone lies between the depth intervals 0ft to 5076 ft (1538.18 m), and comprised mainly thick sand bodies with few very thin shale interbeds (Figure 12.). The second zone extends from the depth of 5076 ft (1538.18 m) to about 12900 ft (3909.09 m) and can be regrouped into upper and lower parts. The upper part shows a characteristic where the sandstone intervals are thicker than the shale, whereas in the lower part, a reversed situation is the case. This zone is equivalent to the zone of 1.35 s to 2.80 s two ways travel time, observed from the seismic record and can be assigned to the Agbada Formation (Doust & Omatsola, 1990; Owoyemi, 2004). Figure 12. Lithology logs of the Tomboy Field Figure 13. Plot of depth against two ways travel time (TWT) in milliseconds Time and depth structural maps Time and depth structural contour maps were produced for the five horizons defined on top of sand bodies , namely, H1 to H5 (Figure 8). Both types of structural contour maps show similar structural relationship. This linear relationship was also corroborated by the linear curve observed from the plot of depth against time using the check shot data of the well BLG1 (Figure 13). Figure 16. Depth structure map of Horizon 2 Figure 18. Depth Structure Map of Horizon 3 Figure 20. Time Structure Map of Horizon 5 The time and depth structure contour maps show system of differently oriented growth faults F1 to F7 (Figures 14-20). Faults F4 and F7 are the major growth faults, dipping towards southwest and are quite extensive. The fault F4 lies centrally within the mapped area and extends up to 85 % of the entire breadth of the mapped area. A rollover anticline formed as a result of deformation of the sediments deposited on the downthrown block of the fault F4. The fault F7, is also extensive and shows sub-parallel relationship with the fault F4. This sub-parallel relationship is sustained in all the structural contour maps. The fault F4 is observed to be closer to the shoreline and can be inter- preted as the active fault, while the F7 is inactive fault, but must have been active in the past and located in offshore direction of the F4. Antithetic faults are F1, F3 and F6, and synthetic faults are F2 and F5, and occur at different positions, at the edge of the mapped area (Figures 14-20). Sealing Potential and Play Prospect of the Study Area Evidence of growth faulting and "rollover" anticline associated with the Tomboy Field can be deduced from the time and depth structural contour maps (Figures 14 to 20). The trapping potential of the field can be attributed to faults or anticlines, acting either as fault assisted or anticline closures respectively (Orife & Avbovbo, 1982; Sales, 1997). Anticlinal and fault assisted closures are regarded as good hydrocarbon prospect areas in the Niger Delta (Weber & Daukoru, 1975). Trapping of hydrocarbons in an anticline is simply by means of closure which may be dependent or independent on faults. The rollover anticlines are formed on the downthrown block of the fault F4, which indicate structural closure in these areas (Figures 14-20). The sealing capability of the faults is dependent on the amount of throws and shale/clay smeared along the fault planes (Busch, 1975; Weber & Daukoru, 1975). According to Weber & Daukoru (1975), faults can be sealing if either the throws are less than 492 ft (150 m), or the amount shale/ clay smeared along the fault planes is greater than 25 %. The average throws of the major faults F4 and F7 calculated are 570.8 ft (173 m) and 511.0 ft (154.85 m) respectively (Tables 1 and 2). Judging by the amount of throws, the faults F4 and F7 are not sealing. However, they are probably sealing, considering the amount of shale/clay smeared along the fault plane. Generally, in the Niger Delta, as reported by Weber & Daukoru (1975), the soft and over- pressured Akata Shale, in most cases rises up to fill the fault zone, thus enhancing their sealing capabilities. Table 1. Table showing throws of fault F4 HORIZONS Downthrow Depth/feet Upthrow Depth/feet Throw of Fault Horizon 1 1029.7 9787.5 505.8 Horizon 2 9833.9 9251.3 582.6 Horizon 3 9185.9 8650.0 535.9 Horizon 4 9099.1 8423.6 675.5 Horizon 5 8442.1 7887.7 554.4 Average: 570.8 Table 2. Table showing throws of fault F7 HORIZONS Downthrow Depth/feet Upthrow Depth/feet Throw of Fault Horizon 1 10767.0 11072.9 305.7 Horizon 2 10216.2 10672.9 456.7 Horizon 3 9367.07 100035.07 668.0 Horizon 4 9034.96 9327.47 592.5 Horizon 5 8302.8 8834.93 531.1 Average: 511.0 It can be deduced from this study that the wells were located to target the rollover anticline formed on the downthrown side of the fault F4 (Figures 14-20). The oil and gas reserves recoverable deduced from the time and depth structure maps vary widely (Weber & Daukoru, 1975). The height of oil above the spill- point and the geographic extent of oil pool are directly related to the type of closure in which the hydrocarbons are trapped. Individual prospects of the closures, as illustrated in the Figures 14 to 20, can be ascribed as good prospect (Weber, 1971). Depositional environment In the absence of biostratigraphic and other well data, a combination of gamma ray and resistivity curve signatures were used to deduce the depositional environments based on their charac- teristic patterns from mainly the well BLG 1. Various depositional environments including point bars, distributary channel, distributary mouth bar, barrier bar, regressive sand, tidal flat, barrier foot and tidal channel fill were identified within the subsurface of the Tomboy Field (Figures 21a-21e). These are based on log characteristics and details as discussed in Adesina (2007). Figure 21a. Gamma ray and Resistivity Logs showing depositional environments from depth interval between 4000 ft (1363.63 m) to 6500 ft (1969.69 m) within well BLG1. Figure 21b. Gamma ray and Resistivity Logs showing depositional environments from depth interval between 6500 ft (1969.69 m) to 8000 ft (2424.24 m) within well BLG1 Figure 21c. Gamma ray and Resistivity Logs showing depositional environments from depth interval between 8000 ft (2424.24 m) to 10000 ft (3030.30 m) within well BLG1 Figure 21d. Gamma ray and Resistivity Logs showing depositional environments from depth interval between 10000 ft (3030.3 m) to 11500 ft (3484.84 m) within well BLG1. Conclusions Seismic and well log data have been used to illustrate structural characteristics of identified sand bodies within the subsurface of the Tomboy field. This was made possible by creating time and depth structural contour maps of five horizons using the GeoGraphix in-terpretational tool. The time and depth structure maps show subsurface struc- tural geometry and possible hydrocarbon trapping potential. Two major growth faults, namely F4 and F7, were observed to extend throughout the entire mapped area. The F4 is the active growth fault located near the shoreline, while F7 is an older inactive fault located offshore which must have been active in the past. The rollover anticline exists at the down-thrown block of the fault F4, which is suggestive of probable hydrocarbon accumulation potential of the sand bodies. The depo-sitional environments identified were barrier bar, channel fill, tidal flat, tidal channel, point bar, distributary mouth bar and tidal ridge. These can serve as reservoirs for the accumulation of oil and gas. It can be deduced from this study that the four wells located in the Tomboy field were drilled to target the rollover anticline formed on the downthrown block of the fault F4. This study, however, can provide additional information for precise well placement in further exploration and production of oil and gas. Within the limits of the available data, it is recommended that further studies should include integration of velocity (check shot) and biostratigraphic data of all the wells. This will provide more reliable data for interpretation of the depositional environments. Ackowledgements The authors are grateful to the management and staff of Chevron Texaco Nigerian Limited for provision of data used in this study. We appreciate the invaluable technical assistance of the staff of Geosciences Solution, Lagos. Mr Bayo Akinpelu of Fixital Nigeria Limited, cannot be forgotten for the payment Figure 21e. Gamma ray and Resistivity Logs showing depositional environments from depth interval between 11500 ft (3484.84 m) to 12500 ft (3787.87 m) within well BLG1. made for the renewal of the license of the Geographix software of the Subsurface Laboratory, Geology Department, University of Ibadan where the interpretation of this work was carried out. We are extremely grateful to TOTAL Nigeria, for sponsorship to present this paper at the 2007 International Conference of the Nigerian Association of Petroleum Explorationist (NAPE) held in Abuja. References Adesina, A. D. (2007): Aspects of structures and depositional environment of sand bodies within Tomboy Field, offshore western Niger Delta, Nigeria. Unpublished M. Sc. thesis, Department of Geology, University of Ibadan 88p. Armentrout, J. M., Kanschat, K. A., Meisling, K., Tsakma, J. J., Antrim, l., Mcconnell, D. R. (2000): Neogene turbidite systems of the Gulf of Guinea continental margin slope, offshore Nigeria, in Bouma. A. H., and Stone, C. G., eds., Fine Grained Tur-bidite Systems: American Association of Petroleum Geologists; Memoir 72, and SEPM, Special Publication 68, p. 93-108. Burke, K. (1972): Longshore drift, submarine canyons and submarine fans in development of Niger Delta. American Association of Petroleum Geology Bulletin; Vol. 56, p. 1975-1983. Busch, D. A (1975): Influence of growth faulting on sedimentation and prospect evaluation. American Association of Petroleum Geologist Bulletin; Vol. 59, No. 3, p. 414-419. Diedjomahor, J. O., Kluth, c. F., Frost, E. G., Mellors, R. (2002): The role of fault kinematics and capture in the western Niger Delta and the control of sediment and reservoir distribution. American Association of Petroleum Geologists, Bulletin; Vol. 88, No. 13 (supplement), p. 1-5. Doust, H., omatsola, M. E. (1990): Niger Delta, In : J. D. Edwards, P. A Santo- grossi (eds.), Divergent/passive margin basins, American Association of Petroleum Geologists; p. 239-248. Evamy, B. D., Haremboure, J., Kamerling, P., Knaap, W. A., Molloy, F. A., Rowlands, P. H. (1978): Hydrocarbon habitat of Tertiary Niger Delta. American Association of Petroleum Geologists Bulletin; Vol. 62, p. 277-298. Hooper, R. J., Fitzsimmons, R. J., Grant, N., Vendeville, B. C. (2002): The role of deformation on controlling depo-sitional patterns in the south-central Niger Delta West Africa. Journal of Structural Geology; Vol. 24, p. 847859. Klett, T. R., Ahlbrandt, T. S., Schmoker, J. W. & Dolton, J. L. (1997): Ranking of the world's oil and gas provinces by known petroleum volumes: U.S. Geological Survey Open-file Report-97-463, CD-ROM. Knox, G. J. & omatsola, M. E. (1989): Development of the Cenozoic Niger Delta in terms of the escalator regression model and impact on hydrocarbon distribution, In: W. J. M van der Linden, S. A. P. L, Cloetingh, J. P. K., Kaasschieter, W. J. E., van der Graff, J., Vandenberghe, and van der Gun, J. A. M., (eds), KNGMG Symposium on Coastal lowland Geology and Geo-technology, Proceedings: Dordrecht, The Netherlands, Kluwer Academic Publishers, p. 181-202. Larue, D. K. & Legarre, H. (2004): Flow units, connectivity, and reservoir characterization in a wave-dominated deltaic reservoir: Meren reservoir, Nigeria. American Association of Petro- leum Geologists, Bulletin; Vol. 88, p. 303-324. Merki, P. (1972): Structural Geology of the Cenozoic Niger Delta. In: T. F. J. Dessauvagie and A. J. Whiteman (ed). African Geology, Ibadan University Press, pp 635-646. Microsoft Encarta (2006): Reference Library Premium, DVD-ROM. übiüra, D. N. (2006): Comparative study of graphical methods and velocity analysis of 2-D seismic reflection data with application to Niger Delta. Pacific Journal of Science and Technology; Vol. 7, No. 2, p. 204-210. Orife, J. M. & Avbüvbü, A. A. (1982): Stratigraphy and the unconformity traps in Niger Delta. American Association of Petroleum Geologist Memoire; Vol. 32, p. 265. Owoyemi, A. O. D. (2004) The sequence Stratigraphy of Niger Delta, Delta field, offshore Nigeria. M. Sc. Thesis, Texas A&M University, 88 p. Petroconsultants (1996): Petroleum exploration and production database: Houston, Texas, Petroconsultants, Inc. Sales, J. K. (1997): Seals strength versus trap closures-a fundamental control on the distribution of oil and gas. In: R. C. Surdam, (ed.), Seals trap and petroleum system. American Association of Petroleum Geologists Memoir; Vol. 67, pp.57-83 Schlumberger (1985): Log Interpreta-tional Principle/Applications; Schlumberger Educational Services, order no. SMP-7017, Houston. Shannon, P. M. & Naylor N. (1989): Petroleum Basin Studies: London, Graham and Trotman Limited, p 153-169. Short, K. C. & Stauble, A. J. (1967): Outline of Geology of Niger Delta. American Association of Petroleum Geologists Bulletin; Vol. 51, p. 761-779. Stacher, P. (1995): Present understanding of the Niger Delta hydrocarbon habitat, In, M. N. Oti and G. Postma, (eds.), Geology of Deltas: Rotterdam, A. A. Balkema, p. 257-267. Weber, K. J. (1971): Sedimentological aspects of oil fields in Niger delta. Geologie en Mijnbouw; Vol. 50, No. 3, p. 559-576. Weber, K. J. & Daukoru, E. M. (1975): Petroleum geology of the Niger Delta: Proceedings of the 9th World Petroleum Congress, Vol. 2, Geology: London, Applied Science Publishers, Ltd., p. 210-221. Whiteman, A. (1982): Nigeria: Its Petroleum Geology, Resources and Potential: London, Graham and Trotman; Vol. 1 and 11, 394 p. Mineral Policy in the Era of Sustainable Development: historical context and future content Rudarska politika v času trajnostnega razvoja: zgodovinski kontekst in vsebine prihodnosti slavko V. šolar1, *, Deborah J. shields2, Michael D. Miller3 1Geološki zavod Slovenije, Dimičeva 14, SI-1000 Ljubljana,Slovenia 2Colorado State University, Department of Economics, Fort Collins, CO 80526, USA 3South Dakota State University, Department of Economics, Brookings, SD 57007, USA Corresponding author. E-mail: slavko.solar@geo-zs.si Received: May 29, 2009 Accepted: July 09, 2009 Abstract: The goal of public policies is to connect desired ends with practical means toward their achievement. How the desired ends are determined, and whose goals and objectives they incorporate, depends upon the culture and political system of the country in question. With few exceptions, policies change over time to reflect changed perspectives and understanding of the world around us. This is true regardless of the policy area in question. Thus, how societies view and manage their mineral resources has evolved in response to public attitudes, societal needs, economic circumstances, cultural perspectives, political orientations, technological advancements, and geological knowledge. In this paper we examine how the scope of concern has changed for mineral policy. We then review the overarching issues that have in recent years been considered essential components of mineral policies. We point out how neoclassical microeconomics has influenced recent policy design. We then use a market flow diagram to illustrate how policies can be focused at specific market issues. We next discuss mineral resources in the context of sustainable development. We identify issues that become relevant when the frame of reference is enlarged beyond ensuring supply and capturing economic rent. We show that policy based solely on neoclassical economics may not be able to effectively incorporate these issues. Izvleček: Cilj politik je povezati želena stanja s praktičnimi uporabnimi sredstvi z namenom doseganja teh stanj. Kako so določena želena stanja, kakšni so cilji, kako so vključeni v politiko, je odvisno od političnega sistema in stanja v državi. Z manjšimi izjemami se politike spreminjajo glede na spremenjene cilje in poglede na svet. Slednje drži za vse vrste politik. Pogled družbe na mineralne surovine in način, kako z njimi ravna, se spreminjata glede na javnost, potrebe družbe, gospodarske okoliščine, značilnosti nacije, splošne politične usmeritve, stanje tehnološkega razvoja in poznavanje geoloških razmer. Raziskali smo, kako se je menjalo področje prevladujočega interesa rudarske politike. Pregledali smo splošna vprašanja, ki so v preteklih letih tvorila temeljne elemente rudarskih politik, pri čemer smo posebej poudarili vpliv neoklasične mikroekonomije na oblikovanje sodobnih rudarskih politik. Na diagramu prikazujemo, kako se rudarske politike osredinjajo na specifična vprašanja trga. Poleg tega obravnavamo mineralne surovine v kontekstu načel trajnostnega razvoja, pri čemer identificiramo relevantna vprašanja, kot je okvir politike, širši od zagotavljanja oskrbe z mineralnimi surovinami in zajetja ekonomske rente. S tem dokazujemo, da rudarska politika, temelječa samo na neoklasični ekonomiki, ne vključuje vseh odprtih vprašanj. Key words: mineral policy, sustainable development, neoclassical economics, ecological economics Ključne besede: rudarska politika, trajnostni razvoj, neoklasična ekonomika, ekološka ekonomika Introduction The purpose of public policy is to direct or control actions by government bodies or the public so as to achieve desired ends or objectives. Policies can range from the very specific, i.e., a detailed course of action or program of activities, to the general, i.e., an overall plan embracing identified goals, or even to the conceptual, i.e., a general expression of societal purpose. Which goals are pursued depends upon the values and interests of the people involved in policy creation. Originally, rulers made policies. However, power may devolve over time from absolute rulers to elites to (more or less) democratic governments to the public. And when a country moves along this continuum, the range of issues worthy of consideration in policy broadens to incorporate the needs and interests of the people rather than only those of the ruling classes. The authors described this gradual evolution in a prior paper (Shields & Šolar, 2006). Recent history was divided into eras, each of which saw major changes in thinking about the nature of the relationship between the government, the economy, workers, the environment and society at large. This expansion of the scope of concern is closely linked to general societal development. The concept of a progression is demonstrated by the changing thinking about mineral supply over the past 100+ years (Figure 1) (Shields & Šolar, 2006): • Pre-industrial era - concern about access to deposits; • Industrial evolution - concern about capitalists, industry, and economic markets; • Late industrial era - concern about workers; • Post industrial era - concern about environment; • End of the millennium - concern about social impacts and preferences; and • Twenty first century - concern about intra- and intergenerational equity. The focus of the first two eras was ensuring the availability of mineral resources. The third era dealt with the rights and protection of workers. The fourth era can be seen as an extension of the third in that it involves protection of the environment. The rise of environmental consciousness was contemporaneous with the rise of economic liberalism in the latter half of the 1900's. People began to understand more clearly that human societies exist within and are ultimately depen- o fl o U «4H O u & o C/2 Equity Community Environment Workers Markets and Capital Discovery and Access PREHISTORY 1800's Early 1900's Late 2000 1900's + FUTURE Time ft ft -called "local stanpard deviation" in the CAE method: 1=1 El = ± k-k f- (7) n=1 Such interpretation of the CAE equa-ions allows us to estimate the corresponding probability distribution and the median value. Note, that the probability density function is composed of weights An for ascending order of the corresponding values Vn. The briefly presented CAE method was applied for the prediction of the ultimate drift of the RC columns. The experimental database used in this study is based mainly on the PEER database prepared by the University of Washington. The prediction of the ultimate drift is limited only to the columns which failed in flexure since the limited num- zahn86u8 tana90u7 suguc15h to .o o (d) Sl% zho21408 StDev = 0.04 f/a CoV = 0,04 p = 4.30 5 dl% ) -0 9 OS 0.7 ■ o.e ■ 0 5 04 0.3 02 01 0^ (e) StDev = 1.15-|Vo SoV - 0.27 p = 1.13 sak90b6 mug89ah2 Figure 1. Examples of empirical cumulative probability distributions (black line) in predictions of ultimate drift for randomly chosen RC columns from the PEER database and reference normal (red line) and log-normal (green line) distributions. Vertical red line indicates mean value n ber of column specimens (so-called model vectors with components b) in the PEER database failed in shear and therefore the existing database is not yet appropriate for prediction of ultimate drift of columns failed in shear. By knowing the empirical probability distribution of the sample (RC column), the application of Kolmogorov-Smirnov test (K-S test) can give us the information on the type of known probability distribution. The K-S test is a form of minimum distance estimation used as a nonparametric test of equality of one-dimensional probability distributions. Kolmogorov-Smirnov statistic quantifies a distance between the empirical distribution function of the sample and the cumulative distribution function of the reference distribution (i.e normal and log-normal in our study). Samples are standardised and compared with a standard normal and log-normal distribution, what is equivalent to setting the mean and variance of the reference distribution equal to the sample estimate. Empirical cumulative probability distributions predicted by CAE method and reference normal and log-normal distributions are shown in Figure 1 for selected columns from the PEER database. The null hypothesis (H0) for each RC column from the PEER database was the assumption that the ultimate drift is distributed normally or log-nor- mally with expected values of S respectively). The rejected level is at a = 0.01. It turns out that for about 5 2 % of RC columns from and E2a (mx and ¡dx, the PEER datmabase (156 specimens) the null hypothesis can not be rejected (i.e. columns in Figures 1a and 1b). On the other hand, the rest of RC columns for which the n511 hypothesis is rejected (predicted ultimate drift is NOT distributed norma1ly or log-normally), typically and gs to similar columns with very different drifts (Figure 1c), to columns with lar1e similarity with one column m the database (Figure 1d) or to columns with large nimilarity with two or m e columns in the database (Figure 1e) or to molumns with small values of p (Figure n f). In all these cases relatively large weights An are attributed to them and consequently K-S statistics gets relatively high values which reject the null hypothesid Note, that the existing PEER database is the largest an the most detailed database on RC columns for the time being. It is also known that sample RC c olum ns are not distributed randomly and that the size of the datmbase is s2ill small for more reliaWe analysis. Aa^ons believe that the extended database would solve this problem. Nevertheless, from the engineering point of view, the obtained results indicate that the distribution of ultimate drift, which is predicted by the CAE method, roughly corresponds to the normal or log-normal probability distribution. The average "local coefficient of variation" (CoV), which is the ratio between the "local standard deviation" and predicted mean value, amounts from zero up to 0.9 in some very rare cases, with an average value of 0.35 and standard deviation of 0.16. Through error and trial procedures it was decided to use a value of 0.4 for CoV in case of assumed log-normal distribution. Furthermore, this value may be considered as a good approximation of CoV in PBEE, especially when it is compared to value of 0.6, obtained by Fardis & Biskins (2003). Note that use of average CoV for prediction of ultimate drifts of RC columns of a building represents a simplification, which can significantly reduce the number of time history analyses (simulations) needed for sufficiently accurate prediction of seismic response parameters, and it does not significantly affects the results, since similar types of columns are usually used in a building. Application The aim of the presented example is to demonstrate the influence of some uncertain input variables of the structural model, especially the ultimate drift (rotation) in columns, on the seismic response parameters. For that reason, the relationship between the seismic intensity measure (peak ground acceleration) and the seismic response parameters (maximum story dirft) was determined for a four storey reinforced concrete frame by using the extended incremental dynamic analysis (extended IDA) (Dolsek, 2009). The four-storey reinforced concrete frame had been designed to reproduce the design practice in southern European countries about forty to fifty years ago and pseudo-dynamically tested in full scale at ELSA Laboratory (Figure 2) (Carvalho & Coelho, 2001). However, the frame can also be typical of buildings built more recently, but without the application of capacity design principles (especially the strong column - weak beam concept), and without up-to-date detailing. The elevation and typical reinforcement in the columns of the four storey frame are presented in Figure 3. The design base shear coefficient amounted to 0.08. In the design, concrete of quality C16/20 and smooth steel bars of class Fe B22k (according to Italian standards) were adopted (Carvalho & Coelho, 2001). Later the strength of material was measured since the pseudo-dynamic tests were performed for the structure. The mean strength of the concrete amounted to 16 MPa, that is less than adopted in the design (fcm for C16/20 is 24 MPa), and the mean yield strength of the steel amounted to 343.4 MPa. Beam and column flexural behaviour was modelled by one-component lumped plasticity elements, composed of an elastic beam and two inelastic rotational hinges (defined by the moment-rotation relationship). The element based on the assumption of an inflexion point at the midpoint of the element was employed in nonlinear static and dynamic analyses. The schematic moment-rotation relationship of the inelastic rotational hinge is shown in Figure 4a. The yield (Y) and the maximum (M) moment in the columns were calculated taking into account the axial forces due to the vertical loading on the frame. The effective beam width of 75 cm and 125 cm were determined according to the Eurocode 2 (CEN, 2004) procedure for the short and long beams, respectively. The characteristic rotations, which describe the moment-rotation envelope of a plastic hinge, were determined according to the procedure described by Fajfar et al. (2006). The ultimate rotation 0 in Figure 2. The four-storey reinforced concrete frame building which was tested at ELSA Laboratory Figure 3. View and typical reinforcement of the columns of the reinforced concrete frame 0 0 /rad 0 /rad a) schematic b) first set of structural models c) second set of structural models Figure 4. The moment-rotation relationship of column plastic hinge: a) schematic representation, b) column C at second storey for first set of structural models and c) column C at second storey for second set of structural models the columns at the near collapse (NC) limit state (see Figure 4a), which corresponds to a 20 % reduction in the maximum moment, was estimated by means of the CAE method (Perus et al., 2006). For the beams, the EC8-3 (CEN, 2005) formulas were used, the parameter yel being assumed to be equal to 1.0. Due to the absence of seismic detailing, the ultimate rotations were multiplied by a factor of 0.85 (CEN, 2005). The extended IDA analysis was performed for two sets of structural models, which reflected different sources of uncertainty. Each set consisted of 20 structural models, which were determined based on the Latin Hypercube Sampling method employed in the extended IDA (Dolsek, 2009). In the first set of structural models the following sources of uncertainties were considered in the analysis: mass, strength of the concrete and that of the reinforcing steel, effective slab width and damping, whereas in the second set of structural models also the model for determining the initial stiffness and ultimate rotation in the plastic hinges of the beams and columns was adopted uncertain. All the input random variables considered for the determination of the set of structural models were assumed to be uncorrelated. The statistical characteristics of the input random variables are presented in Table 1. The initial stiffness and ultimate rotation in the plastic hinges of the beams and columns was considered deterministic in the first set of structural models, while in the second set all input random variables were considered for determination of the set of structural models. In addition to two sets of structural models, which reflect epistemic uncertainties, the deterministic structural model was also used for determination of the relationship between the peak ground acceleration and the maximum storey drift. In order to demonstrate the difference between the structural models used in analysis, the moment-rotation relationship of plastic hinge in the column C at second storey is presented for the two set of structural models (Figure 4b and 4c) and compared to the moment-rotation relationship of deterministic model. It can be observed that the dispersion in the moment-rotation relationship is significantly increased in the case of the second set of structural models, since in this case the initial stiffness and ultimate rotation of beams and columns are considered as random variables which have high coefficient of variation. Table 1. The statistical characteristic of the input random variables Name Mean or Median* CoV Distribution Mass 1st storey m1 46 t 0.1 normal Mass 2nd storey m2 46 t 0.1 normal Mass 3rd storey m3 46 t 0.1 normal Mass 4th storey m4 40 t 0.1 normal Concrete strength f J cm 16 MPa 0.2 normal Steel strength fy 343.6 MPa 0.05 log-normal Effective slab width beff 75 cm or 125 cm 0.2 normal Damping 2 % 0.4 normal Initial stiffness of the columns © y,c 1-computed 0.36 log-normal Initial stiffness of the beams ©b y,b 1-computed 0.36 log-normal Ultimate rotation of the columns © u,c 1-computed 0.4 log-normal Ultimate rotation of the beams © b u,b 1-computed 0.6 log-normal *mean is shown for normal distribution and median for log-normal distribution Figure 5. Maximum drift as a function of peak ground acceleration. Results are presented for two ground motion records and for a) first and b) second set of structural model Two ground motion records were selected from the European strong motion database (Ambraseys, 2000) aiming to demonstrate the influence of the uncertainties on the seismic response parameters. Both ground motion records were recorded on stiff soil during the Montenegro earthquake in 1979. IDA analysis was performed for each ground motion record. The peak ground accel- eration, corresponding to instability, was determined with tolerance of 0.005 g. Selected results of IDA analysis are presented in Figure 5. In addition to so called IDA and capacity points, which, respectively, represents the maximum storey drift of one nonlinear dynamic analysis for a given ground motion record and the peak ground acceleration, which corresponds to the global Table 2. Peak ground acceleration capacity of deterministic model, median peak ground acceleration capacity and its dispersion for probabilistic model with and without the probabilistic ultimate rotation in columns (for two ground motion records) Ground motion record Deterministic model Probabilistic model First set of struct. models Second set of struct. models ag,c/g ag,c/g Pg,c ag,c/g Pg,c 196x 1.775 1.715 0.197 1.637 0.403 197y 0.473 0.474 0.100 0.477 0.255 dynamic instability of the structure, the IDA curves of the deterministic model and the summarized IDA curves (median ± o) of the first and second set of structural models are also presented. The results in Figure 5 indicate that the influence of uncertainties on the seismic response parameters can be neglected if the peak ground acceleration is much less than the peak ground acceleration which causes the global dynamic instability of the structure. For this range of peak ground acceleration the summarized IDA curves based on the first and second set of structural models are practically the same in comparison to the IDA curve which is determined for the deterministic model. However, uncertainties can reduce the peak ground acceleration, which corresponds to global dynamic instability of the structure, what can be observed for the ground motion record 196xa. In this case the median capacity in terms of peak ground acceleration is reduced for about 3 % and 8 % if compared to that of the deterministic model. For the other ground motion record the capacity is practically the same for both sets of structural models and also for the deterministic model (Table 2). In addition, the significant increase in the dispersion of the seismic response parameters can be observed for the second set of structural models since high uncertainties were used in determination of the initial stiffness and ultimate rotation of columns and beams. The dispersion in peak ground acceleration, which corresponds to global dynamic instability, is increased for about 100 % in the case of second set of structural model if compared to dispersion calculated from the first set of structural models, and it is also significantly dependent on selected ground motion records (Table 2). Conclusions The PBEE seeks to improve quantification of deformation capacity of structural members. Therefore, the research presented here deals with the prediction of ultimate drift with special consideration on dispersion measure. The CAE method was applied for this purpose to the RC columns which fails in flexure. It was found that empirical probability distribution of ultimate drift of RC columns roughly corresponds to normal and/or log-normal distribution. Moreover, an average value of 0.4 for CoV in the case of assumed log-normal distribution is proposed to be used in PBEE. It should be noted that the use of average CoV for prediction of ultimate drifts of RC columns of a building represents a simplification. Namely, it does not significantly affect the results, since similar types of columns are usually used in a building. However, uncertainty in prediction of ultimate drift with the CAE method is reduced if compared with procedure proposed by Fardis & Biskins (2003). The reduced uncertainty can significantly reduce the number of time history analyses (simulations) needed for sufficiently accurate prediction of seismic response parameters. The influence of uncertainties on the seismic response parameters was dem- onstrated with an example of four storey RC frame building. The results indicate that the influence of uncertainties on the median value of seismic response parameters can be neglected if the peak ground acceleration is much less than the peak ground acceleration which causes the global dynamic instability of the structure. On the other hand, the increase in the dispersion of the seismic response parameters can be observed for the structural models with high uncertainties in determination of the initial stiffness and ultimate rotation of columns and beams. Therefore, it is important to determine the deformation capacity (i.e. ultimate drift) of RC structural members with predictive models which gives the lowest uncertainties and consequently more accurate prediction of seismic risk. Using the CAE method, as demonstrated in this study, represents a step toward this goal. Acknowledgements The results presented in this paper are based on work supported by the Slovenian Research Agency. References Ambraseys, N., Smith, P., Bernardi, R., Ri-naldis, D., Cotton, F., Berge-Thierry, C. (2000): Dissemination of European Strong-Motion Data. CD-ROM collection. European Council, Environment and Climate Research Programme. Carvalho, E. C., Coelho, E. (Editors) (2001): Seismic assessment, strengthening and repair of structures. ECO-EST2-ICONS Report No. 2, European Commission - "Training and Mobility of Researchers" Programme. CEN. Eurocode 2 (2004): Design of concrete structures - Part 1-1: General rules and rules for buildings. EN 1992-1-1, European Committee for Standardisation, Brussels, December 2004. CEN. Eurocode 8 (2004): Design of structures for earthquake resistance. Part 1: General rules, seismic action and rules for buildings, Brussels, December 2004. CEN. Eurocode 8 (2005): Design of structures for earthquake resistance. Part 3: Strengthening and repair of buildings. EN 1998-3, European Committee for Standardisation, Brussels, March 2005. Deierlein, G. G. (2004): Overview of a comprehensive framework for earthquake performance assessment, PEER Report 2004/05 Performance-Based Seismic Design - Concepts and Implementation (Eds. Fajfar and Krawinkler). Dolsek, M. (2009): Incremental dynamic analysis with consideration of model- ling uncertainties. Earthquake Engineering and Structural Dynamics; Vol. 38,pp.805-825. Fajfar, P., Dolsek, M., Marusic, D., Stra-tan, A. (2006): Pre- and post-test mathematical modelling of a plan-asymmetric reinforced concrete frame building. Earthquake Engineering and Structural Dynamics; Vol. 35, pp. 1359-1379. Fardis, M. N., Biskins, D. E. (2003): Deformation capacity of RC members, as controlled by flexure or shear. Performance-based engineering for earthquake resistant reinforced concrete structures: A volume honoring Shunsuke Otani. Kabeyasawa T, Shi-ohara H, (eds.), University of Tokyo, pp.511-530. FIB (2003): Displacement-based seismic design of reinforced concrete buildings. State-of-the-Art Report Prepared by Task Group 7.2, Bulletin 25, (Federation international du beton). Grabec, I., Sachse, W. (1997): Synergetics of Measurement, Prediction and Control, Springer-Verlag. Panagiotakos, T. B., Fardis, M. N. (2001): Deformations of reinforced concrete members at yielding and ultimate. ACI Structural Journal; Vol. 98, No. 2, pp. 135-148. PEER Reinforced Concrete Column Test Database [online]. University of Washington [cited 20. 10. 2008]. Accessible on Internet: http://www. ce.washington.edu/~peera1/. Perus, I., Püljansek, K., Fajfar, P. (2006): Flexural deformation capacity of rectangular RC columns determined by the CAE method. Earthquake Engineering and Structural Dynamics; Vol. 35, No. 12, pp. 1453-1470. Pirtüvsek-Veckü, T., Kugler, G., Fajfar, P., Fazarinc, M., Perus, I., Tercelj, M. (2007): Hot forming of AISI D2 steel. RMZ - Materials and Geoenviro-nment; Vol. 54, No. 1, pp. 1-14. Pirtovsek-Vecko, T., Fazarinc, M., Kugler, G., Tercelj, M. (2008): Increasing of hot deformability of tool steels - preliminary results. RMZ - Materials and Geoenvironment; Vol. 55, No. 2, pp. 147-121. Extra machinability modeling Modeliranje povečane obdelovalnosti Miha Kovačič1, 2 *, Matej Pšeničnik2 1ŠTORE STEEL, d. o. o., Štore, Slovenia ^University of Nova Gorica, Laboratory for Multiphase Processes, Nova Gorica, Slovenia Corresponding author. E-mail: Miha.Kovacic@store-steel.si Received: December 17, 2008 Accepted: June 06, 2009 Abstract: The steels with extra machinability are made according to special technological process. It depends on several parameters, particularly on the steel chemical composition, whether the steel will meet the criterion of extra machinability. By special test it is established whether the steel has extra machinability or not. In our researches the prediction of machinability of steels, depending on input parameters, was performed by logistic regression and genetic programming. The research shows that genetic programming model performs better. The best model developed during the simulated evolution was practically verified. Izvleček: Jekla s povečano obdelovalnostjo so izdelana s posebnim tehnološkim postopkom. Povečana obdelovalnost jekla je odvisna od mnogih parametrov, predvsem pa od kemične sestave. Obdelovalnost jekla se določa na podlagi posebnega preizkusa. V naši raziskavi smo za napovedovanje obdelovalnosti jekla uporabili logistično regresijo in genetsko programiranje. Rezultati kažejo, da se bolje obnese metoda genetskega programiranja. Rezultati modela so bili preizkušeni v praksi. Key words: steel, extra machinability, modeling, logistic regression, genetic programming Ključne besede: jeklo, povečana obdelovalnost, modeliranje, logistična regresija, genetsko programiranje Introduction In general, tool steels are divided into ordinary steels and steels with extra machinability. These two groups differ in the technology of steel manufacture, which influences the steel properties during machining processes (e. g. turning, milling). In case of steel with extra machinability it is possible to reach much higher resistance of cutting tools even with higher cutting speeds, therefore the price of such steels is 10 % higher on the average than the price of the ordinary steel.[1] The steels with improved machinabili-ty retain all good qualities of ordinary steels their advantage being that they allow machining at 25-50 % higher cutting speeds, 4-6 times lower tool wear and 30 % reduction of machining cost.[1] In case of steel with extra machinabi-lity the molten metal is treated with calcium, which improves their machining properties. Instead of aluminium oxides the steel with extra machina-bility contains calcium aluminates of 2-20 pm size which are of regular forms and uniformly scattered. In this steel the calcium aluminates have sulphide surface. The heat in the cutting zone softens the sulphide surface and ensures the cutting tool to have lubrication effect. As a result, the tool wear in lower and higher machining speeds are allowed.[1] The test of the steel machinability is preformed according to the technological standard ISO 3685.[2] The test process is demanding and time-consuming. As long as the data on machina-bility are not known, the steel cannot be included in the further technological process. If the steel does not reach the degree of extra machinability it is considered to be ordinary steel. The steel machinability is influenced particularly by the chemical composition. As there are several chemical elements in the steel its machinability is hard anticipate and predict. In addition, also other technological parameters change, which additionally make the steel machinability prediction difficult. In the paper prediction of steel machinability by logistic regression and genetic programming was used. The both methods were also compared. Prediction of machinability of steel helps to avoid time-consuming and expensive testing of steel machinability and to contribute to improvement of the material flow in the production process. Test of tool resistance Appropriateness of steel with extra machinability is verified by parameter v15 which is prescribed for each grade of time t = 22.6 min, within which tool steel. wear takes place, v15 amounts to: The parameter v15 is the speed of cutting of the tool which is worn out within 15 min. The tool wear is prescribed. The test of tool resistance is preformed on a CNC lathe. That test is carried out for each batch. The batch is the quantity of steel cast as a whole in the steelworks. The mass of one batch is 52 000 kg. Each batch is identified by its identification number. The steel sample for finding out the ma-chinability must have the diameter of at least 60 mm and the minimum length of 500 mm. After machining (turning) without cooling, within time t (approximately fifteen minutes) and with selected speeds, the wear of the cutting insert is measured under a microscope (Figure 1). The tip of the insert (VBB) may be worn out for not more then 0.30 mm and the entire insert edge (V ) ° v BB max/ for not more than 0.60 mm. Afterwards, the parameter v15 is calculated by Taylor's equation:[3] v • tn = C (1) where v is cutting speed, t is cutting time, n is constant depending on tool material (insert). Constant n for ceramic inserts is 0.25. v-i"=vI5-15" (2) Vt 0.25 = v15-15 -0.25 0.25 v15=v- v15 = 330 150.25 22.60'25 15 0.25 = 365.6 m /min BB max Figure 1. Side wear of the insert Experimental background The data were collected in the period of 13 months in the factory Štore Steel Ltd. from Slovenia. The most influencing parameters are the sample diameters and the chemical elements (calcium, oxygen and sulphur) necessary for production of steel with extra machinability. 146 batches were made. Out of them 125 were adequate. If the batch is adequate this means when parameter v15 in the individual batch exceeds With cutting speed v = 330 m/min and the prescribed value ^ for that bateh. The prescribed value of parameter v15 = 85.61 %. The number of each steel depends on the grade of steel. Conse- grade specimens and the average chem- quently, during that period the success ical composition and prescribed v15 for of production of steels was 21/146 steel grade is presented in Table 1. Table 1. The number of each steel grade specimens and average chemical composition and prescribed v Steel grade Number of specimens w(Ca)/% w(O)/% w(S)/% v15/(m/min) 16MnCrS5 2 0.0305 0.034 0.0275 410 C45 139 0.0293 0.0462 0.0270 360 C50 2 0.0235 0.0145 0.021 360 C15 1 0.029 0.019 0.028 450 St70.2 2 0.03 0.0375 0.029 360 The experimental data and extra machinability suitability are presented in Table 2. If the batch of steel is adequate then it is marked with logical variable 1 and with 0, if it is not. Table 2. The experimental data # Batch number Steel grade Sample diameter w(Ca)/% w(O)/% w(S)/% V15 Prescribed V15 Extra machinability 1 36968 C45 19.0 0.024 0.019 0.031 327 360 0 2 37101 16MnCrS5 60.0 0.026 0.044 0.027 453 410 1 3 37236 C50 70.0 0.026 0.005 0.022 308 360 0 4 37237 C50 70.0 0.021 0.024 0.02 346 360 0 143 37322 C45 70.0 0.027 0.018 0.025 261 250 1 144 37358 C45 70.0 0.033 0.042 0.028 452 450 1 145 37359 C45 70.0 0.029 0.044 0.022 459 450 1 146 37360 C45 68.0 0.033 0.046 0.025 438 410 1 Extra machinability modeling Evaluation of models were determined by Bayesian analysis (true positive TP, true negative TN, false positive FP, false negative FN) applying sensitivity SENS = TP/(TP+FN), specificity SPEC = TN/(FP+TN), positive predictive value PP V= TP/(TP+FP) and negative predictive value NPV = TN/(FN+TN). The higher are values of mentioned parameters the better model fits to experimental data. According to the logistic regression results the logistic mathematical model for extra machinability is: (3) P ' lg 1 -p = 0.058 cp + 123.607 • w{Ca) + +101.616 • w(0) + 326.759 w(iS)-18.537 where p is the probability of steel not being extra machinability steel. If the probability p was lower then 0.5, then the extra machinability was denoted as 1 otherwise as 0. The parameters in the mathematical models for extra machinability are denoted as: • q> - sample diameter • w(Ca)/% - mass fraction of calcium • w(O)/% - mass fraction of oxygen • w(S)/% - mass fraction of sulphur Logistic regression modeling The most important results of logistic regression are presented in Table 3. The logistic regression model sensibility is 0.976, specificity 0.524, positive predictive value 0.924, negative predictive value 0.786 and test efficiency 0.911. Genetic programming modeling Genetic programming is probably the most general evolutionary optimization method.[4-6] The organisms that undergo adaptation are in fact math- Table 3. Logistic regression results Parameter B S. E. Wald df Sig. Exp(B)

)- 2.32712 1.11863 -(p + w(0)-w(5)- 1.70735 2.32712 --+ w(0) +- M.O) w(0) + w(S) J w(0)(2.32712+w(5')) the greatest permissible depth in creation of population 6, the greatest permissible depth after the operation of crossover of two organisms 10 and the smallest permissible depth of organisms in generating new organisms 2. Genetic operations of reproduction and crossover were used. For selection of organisms the tournament method with tournament size 7 was used. We have developed 100 independent civilizations of mathematical models for prediction of extra machinability. Only one out of 100 is presented in eq. 4 (page 343) With sensibility of 1, specificity 0.810, positive predictive value 0.969, negative predictive value 1 and test efficiency 0.973. Conclusions Due to their specific properties if compared with ordinary steels, the steels with extra machinability will represent a growing share on the market. Their advantage over the remaining steels, in particular, is that they can be machined at higher machining speeds and that they assure smaller cutting tool wear. In researches two approaches were used for predicting the steel machin-ability - logistic regression and genetic programming. Evaluation of models was determined by Bayesian analysis. The logistic regression model was obtained with sensibility 0.976, specificity 0.524, positive predictive value 0.924, negative predictive value 0.786 and test efficiency 0.911. The best genetic programming model (out of 100) performed better with sensibility of 1, specificity 0.810, positive predictive value 0.969, negative predictive value 1 and test efficiency 0.973. Out of 146 values the best model wrongly predicts 4 values; it means that its reliability is 97.26 %. In case of all 4 wrong predictions the model predicts that the steel has appropriate machinability, while in fact it does not have it. Research has shown that by using the genetic programming method for prediction of appropriateness of the steel machinability it is possible to establish efficient planning and optimizing of production, to reduce the costs of researches and the handling changes and, finally, to increase satisfaction of the buyers due to shorter delivery times. The future researches will be focused on testing the mathematical model and optimizing the chemical composition. The prognosis is optimistic. References [1] www.store-steel.si (2009). [2] ISO 3685:1993, Ed. 2, Tool-life test- ra ing with single-point turning tools. [3] Galante, G., Lombardo, A., Passan-nanti A., Tool-life modeling as a stochastic process, Iiteriotioiol journal of machine tools ond manufacture, 1998, 38, 1361-1369. [6] [4] Kovacic, M., Brezocnik, M., Turk, R. (2005): Modeling of hot yield stress curves for carbon silicion steel by genetic programming. Materials ond manufacturing processes, Vol. 20, 1-10. Kovacic, M., Uratnik, P., Brezocnik, M., Turk, R. (2007): Prediction of the bending capability of rolled metal sheet by genetic programming. Materials and manufacturing processes, Vol. 22, 634-640. Koza, J. R. (1999): Genetic programming III. Morgan Kaufmam, San Francisco, 1154 p. Environmental labelling of products with type I labels Ekološko označevanje proizvodov z oznakami tipa I Branislava Crnobrnja, Igor Budak, Milana Ilic, Janko Hodolič University of Novi Sad, Faculty of Technical Sciences, Trg D. Obradovica 6, 21000 Novi Sad, Serbia Corresponding author. E-mail: budaki@uns.ac.rs Received: July 14, 2009 Accepted: July 30, 2009 Abstract: Environmental labelling is the important issue in the actual global framework for more than 20 years. Thanks to the development of a national environmental labelling program of Republic of Serbia this issue is becoming very interesting in our country. In this paper is given a review of national and regional environmental labelling programs, as well as a review of the development of the environmental (eco) labelling. Paper is based on the basic principles of SRPS ISO 14024:2003 standard, with representation of current situation in this area in the Republic of Serbia. Izvleček: Ekološko označevanje je pomembna tema aktualnega globalnega povezovanja že več kot dvajset let. Po zaslugi razvoja lastnega nacionalnega programa ekološkega označevanja v Republiki Srbiji je ta tema postala izredno zanimiva tudi v naši državi. V prispevku je podan prikaz nacionalnih in regionalnih programov ekološkega označevanja, kot tudi pregled prikaza razvoja ekološkega (eko) označevanja. Prispevek temelji na osnovnih principih standarda SRPS ISO 14024:2003 s predstavitvijo aktualnega stanja na tem področju v Republiki Srbiji. Key words: Environmental labelling, Eco label, Type I, ISO 14024 Ključne besede: ekološko označevanje, eko-oznaka, tip I, ISO 14024 Introduction Environmental (eco) labelling is a voluntary method of environmental performance certification and labelling practiced around the world. As primary reasons for eco labels introduction, may be isolated next three: [1] • promotion of development, manufacturing, advertising and using products that causes less influence on the environment, • stimulation of manufacturing which has maximum savings of physical resources using materials liable to recycle, and • to offer customers total and secure information about impact of a product/service on the environment. As an answer on appearance, great number of labels and declarations within this area of life cycle considerations, ISO has identified three broad types of voluntary labels.[2, 3] Type I - a voluntary, multiple-criteria based, third party program that awards a license that authorizes the use of environmental labels on products indicating overall environmental preferences ability of a product within a particular product category based on life cycle considerations. Type II - informative environmental self-declaration claims. Type III - voluntary programs that provide quantified environmental data of a product, under pre-set categories of parameters set by a qualified third party and based on life cycle assessment, and verified by that or another qualified third party. Further in this paper detailed analysis of program for eco labelling fitting under the Type I is presented. Type I eco labelling Standard ISO 14024 was declared in 1999, and it defines Type I eco labels. This international standard is referring to programs of environmental labelling that award eco label to those products which satisfied complex previously defined conditions. In that way label identifies products certified as suitable for the environment, and because of that, usually this type is so called „stamps of approval". Type I label is only given to those products that are in their category classified in range from 15-20 % ecologically the most acceptable. Label points out that product ecologically seen more acceptable than products of same category, and purpose is to stimulate buying products that are ecologically acceptable. Type I environmental labelling programs are voluntary. They can be led by public or private agencies and can be national, regional and international.[4] The aim of Type I eco labelling program is contribution of reducing harm- ful factors on environment by using products for which is declared are more appropriate for environment. Type I eco labelling program overcomes six basic steps: [1, 6] • consultations with interested parties, • product category determination, • creating, testing and exchanging criteria for environmental products, • identifications of characteristics of product functions, • development and implementation of suitable criteria, standards and guiding, and • certification and licensing. General characteristic of symbols that are used with this type of eco labels is that should associate on environment, in combination with symbols which are characteristic for some country/region. Thus, to show at the same time something that country/region is recognizable for (sometimes what is characteristic is bird, flower, leaf ...) and to take care for environment (e.g. green or blue colour).[7] Preview of the current Type I eco labelling program In this chapter is given summary of all national environmental labelling programs, and short presentation of program for eco labelling of European Union, which is regional-international.[3] National programs for Type I eco labelling Programs for Type I environmental labelling start to grow previously on national levels, and country (its institutions) mostly was the main initiator and organizer of development and usage of this kind of program. According to this, regional eco labelling system, with easier way of orientation to customers in buying and choosing services, and because of market coverage begun to develop. [3, 8] Table 1 gives us a summary of appearing program of eco labelling. Table 1. Chronology and summary of programs for Type I eco labelling Label Program Country Starting year jj Blue Angel Germany 1977 1ÏIÏ Develop TCO Development Sweden 1980 II Environmental Choice program Canada 1988 BRA MILJOVAL Sweden 1988 White Swan Nordic Countries Eco Mark Japan Green Seal USA Good Environmental Choice Australia Environmental Choice New Zeland NF Environnement France 1991 Milieukeur Netherlands Eco Mark India Eco Mark South Korea Green Mark Program Taiwan Green Label Singapore Medio Ambiente El Distintiu Umweltzeichen Spain Catalonia Austria 1993 Prijatelj okoliša Croatia Environmental Friendly Product Czech Republic Kornyezetbarat Termek Hungary 1994 Green Label Program Israel 1994 Green Label Thailand Thailand 1994 ® Water Lily Lithuania 1996 0 Ecologically suitable product Slovakia 1998 ë Ekologiczny Poland 2000 w Green Label Hong Kong 2000 Eco Label ENVIRON Environment 2000 Zimbabwe 2000 if,....... Vf LEAF Vitality Leaf Russia 2001 m The Program for Development of Ecological Marking in Ukraine Ukraine 2002 © Green Choice Philippines Philippines 2002 (# 4 BN-* ' Qualidade Ambiental Brazil 2003 O Dimah Uiqhvi»]an Ecolabel Indonezia Indonesia 2006 & Eko oznaka Bosnia and Herzegovina 2009 Regional programs of Type I eco labelling Ministry of council of Denmark, Finland, Iceland, Norway and Sweden, in November 1989 made a decision about adopting a common programme for ecological valuation and marking by the name "Nordic Swan Label". Use of this programme is in jurisdiction of „Nordic Eco-labelling Board". Program covers 69 groups of products. Label is valid for three years, after which revision of criteria is needed.[9] October 1992. Based on the Council Regulation No. 1980/2000 document, the procedure has been revised in September 2000. This was published in The Official Journal of EU on September 21st, 2000 and took the effect three days later.[10] Figure 1. Label of programme for ecological valuation and marking of Denmark, Finland, Iceland, Norway and Sweden „Nordic Swan Label" Figure 2. Typical products with label "Nordic Swan Label" European Union eco labelling program has come to an agreement by Ministry of environment in December 1991, defined by Council Regulation No. 880/92 in March 1992, and became legal in Figure 3. EU eco label The groups of products are developed as a result of the suggestions given by all interested parties, among which are the following:[9] • competent national bodies, • ecological groups/movements, consumers associations, and trade unions and tradesmen. European Commission is responsible for constituting and revising of the criteria for each group of products by giving mandate to a board made of competent bodies and consultation forum that involves all the relevant interested parties - non-governmental organizations like European Bureau for the Environmental Protection, trade and consumers associations.[11] Each EU member state has its competent body receive requests for obtaining of an eco for administrating of the procedure on label and decide whether the products the national level. Competent bodies are satisfactory comparing to a number that have to be independent and neutral of criteria. I uropejm I rinm I c«»laK*l I Ing llnufil iC'iimfK'U'fH lltitlii'v A: I ntcrk-M (¡rmipsi I uruptall tViinm»>\»nri pn.'vt*m m»» 1 SiiiijZfnlii ins UtV k'ht'i IvL'tl i kv'iEUbUon. WniUn^ I'tun i 1 M . H 11 11 I.' 1 1 1 It l>< ^ii'A L'iifccrui 1 >r.iMint: irf .rut-ri» ■ K 1 1 .tIKl < ■ xnulliiliiin M ark vl 'Siinly with Ail Hi H-V\' i iilkiny i ii * v ; | ' 1 ilt.- t'yvk- TVfgulttt* ftvd Kick i<> 1(111 Iiii|>ipi*:«n pt Kt'ir ulult ii .'\vll »p|H I i inttilsvn m C I lLt"J l:i ( ■ il III ill . i 11 Cntiriia IBuH|n»hinjj ni L"riU'riu in _< >1 licial Journal_ Figure 4. Criteria determination procedure scheme[11] The manufacturers whose products fulfil their criteria should get registration package that contains clear, step by step directions for obtaining the EU eco label from competent body. Once the application is filled out, it needs to be handed over to the national competent body who, by attaching their argumentation and recommendation, submits it to the European Commission-European Union Eco labelling Board who brings decision by voting. The procedure for getting EU eco label is graphically presented in Figure 5. The "Global Eco labelling Network"-(GEN) is a non-profit association, founded in 1994 to improve and develop the eco-labelling of products and services world-wide. The EU Eco label Scheme is a full member of GEN.[12] The mission of the GEN is to:[12] serve its members, other eco labelling programs, other stakeholders, and the public by improving, promoting and developing the eco labelling of products, the credibility of eco labelling programs worldwide, and the availability of information regarding eco labelling standards from around the world, faster co-operation, information exchange and harmonization among its members, associates, and other eco labelling programs with regard to eco labelling, facilitate access to information regarding eco labelling standards from around the world, participate in certain international organizations in order to promote eco-labelling generally, and encourage the demand for, and supply of, more environmentally responsible goods and services. Figure 5. Procedure for getting EU eco label[11] Figure 6. Logo of GEN[12] "»WuS1 Figure 7: Two versions of eco label of Republic of Serbia[14] ECO LABELLING IN SERBIA First efforts related to this topic in R. Serbia were done by bringing up the Environmental Law, of which paragraphs no. 53 and 54 determine, respectively award and subtraction of eco label. Label is determined for products intended for universal consumption, process and service, except food, drinks and pharmaceutical products, but licence for using provides Ministry of Environment. This label would be part of Award of Licence for Eco label Application Regulation.[13] In march 2009 was presented and officially published "Rules on closer conditions and procedure for obtaining rights to the use of eco label, elements, layout and use of eco label for products, processes and services",[14] which met the prerequisites for the beginning of the implementation. Conclusions Presented view, which indicates that the countries with national Type I environ- mental programs, suggests that the current informal tools for the management of environmental protection - is growing. Also, in the paper, through the two regional eco labelling programs, especially for eco labelling of the European Union, clearly points out the advantages of these programs, especially in terms of market globalization. It is noted in the review that some Member States of the European Union (United Kingdom, Italy, Slovenia, etc.) did not develop their own programs, but have decided for the implementation of the EU as their national. This fact is interesting from the aspect of Republic of Serbia, which established the National Eco labelling Program last year. Although it is, at first glance, in conflict with the approach of above mentioned countries, the fact that "Rules on closer conditions and procedure for obtaining rights to the use of eco label, elements, layout and use of eco label for products, processes and services" made with great respect to the criteria for categorization and evaluation of products from the EU, indicates that Republic of Serbia elected a similar approach. This 355 Crnobrnja, B., Budak, I., Ilic, M., Hodolic, J. will ensure not only compliance with the EU program in the future, but also quality and credibility of our program, in terms of easier access of domestic Serbian products to the EU market. Acknowledgement Results presented in this article have been obtained in the frame of Tempus project JEP 41156 2006 TIMEA, "Training of Institutions in Modern Environmental Approaches and Technologies". References [1] ISO 14024 (1999): Environmental Management - Environmental Labels and declarations - Type I Environmental Labelling. International Organisation for Standardisation, Geneva. [2] ISO 14020 (2000): Environmental Management - Environmental Labels and Declarations - General Principles. International Organisation for Standardisation, Geneva. [3] Whitelaw, W. (2004): ISO 14001 -Environmental System Handbook. Elsevier, Amsterdam. [4] Ilic, M., Budak, I., Crnobrnja, B., Hodolic, J. (2009): Analysis of Self-Declared Environmental Labels. Materials and Geoenvironment; Vol. 56, No. 1, pp. 74-87. [5] Ilic, M., Budak, I., Crnobrnja, B., Hodolic, J., Kosec, B. (2009): Analy- sis of Self-Declared Environmental Labels and its Application in Serbia. Proceedings of the 6th Research / Expert Conference Quality 2009, pp. 489-494, Neum. [6] BuDAK, I., Kosec, B., Hodolic, J., Ilic, M., Crnobrnja, B., Sokovic, M. (2009): Contribution to the Analysis of Self-Declared Environmental Labels. Proceedings of the 9th International Foundrymen Conference, pp. 32-37, Opatija. [7] Kutz, M. (2007): Environmentally Conscious Mechanical Design. John Wiley & Sons, New Jersey. [8] Crnobrnja, B., Budak, I., Ilic, M., Hodolic, J., Kosec, B. (2009): Analysis of environmental labels and declarations type I - according to SRPS ISO 14024:2003. Proceedings of the Festival of Quality 2009, 4th National Conference on Life Quality, pp. 1-7, Kragujevac (in Serbian). [9] Miljomarkning Sverige AB: www. svanen.nu [10] European Commission: ec.europa.eu [11] The European Eco-Label Catalogue: www.eco-label.com [12] GEN Global Ecolabelling Network: www.gen.gr.jp [13] SRPS ISO 14024 : 2003, Ministry for Spatial Planning and Environment of Republic of Serbia, Belgrade, 2003. [14] Rules on closer conditions and procedure for obtaining rights to the use of eco-label, elements, layout and use of eco-label for products, processes and services, Ministry for Spatial Planning and Environment of Republic of Serbia, Belgrade, 2009. Heat Treatment of Cold Formed Steel Forgings Toplotna obdelava hladno preoblikovanih jeklenih odkovkov Borut Kosec1'*, Matjaž Brezigar2, Gorazd Kosec3, Gabrijela Čevnik4, Milan Bizjak1 University of Ljubljana, Faculty of Natural Sciences and Engineering, Aškerčeva 12, SI-1000 Ljubljana, Slovenia 2ISKRA Avtoelektrika, d. d., Polje 15, SI-5290 Šempeter pri Gorici, Slovenia 3ACRONI, d. o. o., Cesta B. Kidriča 44, SI-4270 Jesenice, Slovenia 4 SIJ, d. d., Gerbičeva 98, SI-1000 Ljubljana, Slovenia Corresponding author. E-mail: borut.kosec@ntf.uni-lj.si Received: May 27, 2009 Accepted: July 07, 2009 Abstract: For economical production of cold formed steel forgings for the automotive industry it is important that they have a long working life. Their corresponding mechanical and thermal properties are achieved by a heat treatment process. In the Slovenian company ISKRA Avtoelektrika they manufacture, with the processes of cold forming, a great number of a different steel forgings for the Slovenian and European automotive industry. During their exploitation they are exposed to the high mechanical and temperature loads. A practical example is presented an optimisation of the heat treatment procedure for typical steel forging (pinion) from the ISKRA Avtoelektrika production program. The practical result of the used heat treatment are (the cold formed) steel pinions with the surface hardness of approximately HRc = 65, and the case hardened depth of the surface layer with the hardness higher than 551 HV1 approximately 0.7 mm. On the basis of the results of corresponding economical studies, supported by technical investigations and analysis, second device (of the same producer, type and capacity) for the heat treatment was installed. Professional paper Izvleček: Za ekonomično proizvodnjo hladno preoblikovanih jeklenih odkovkov za avtomobilsko industrijo je pomembno, da imajo le-ti dolgo obratovalno dobo. Njihove visoke mehanske in toplotne lastnosti se dosežejo s postopki toplotne obdelave. V podjetju ISKRA Avtoelektrika, d. d., izdelujejo s hladnim preoblikovanjem veliko število različnih jeklenih odkovkov za slovensko in evropsko avtomobilsko industrijo. Odkovki so med svojo eksploatacijo izpostavljeni velikim mehanskim in toplotnim obremenitvam. Kot primer je predstavljena optimizacija procesa toplotne obdelave tipičnega jeklenega odkovka (pastorka) iz proizvodnega programa ISKRE Avtoelektrike. Praktičen rezultat izvedene toplotne obdelave so (v hladnem preoblikovani) jekleni pastorki s trdoto površine približno HRc = 65 in površinsko utrjeno plastjo s trdoto HV1 višjo od 551 do globine 0,7 mm. Na podlagi rezultatov izdelanih ekonomskih študij, podprtih s tehničnimi raziskavami in analizami, so v podjetju instalirali drugo napravo za toplotno obdelavo istega proizvajalca, tipa in enake kapacitete. Key words: Heat Treatment, Steel Forgings, Pinion, Temperature Measurements, Automotive Industry Ključne besede: toplotna obdelava, jekleni odkovki, pastorek, meritve temperatur, avtomobilska industrija Introduction In the Slovenian company ISKRA Avtoelektrika they manufacture, with the processes of cold forming, a great number of a different steel forgings (Figure 1) for Slovenian and European automotive industry. The cold formed steel forgings[1] are, during their exploitation, exposed to the both: high mechanical and temperature loads.[2-4] In the frame of this investigation work, the efficiency and quality of the heat treatment (case hardening)[5-10] of the one of the most typical cold formed steel forgings from ISKRA Avtoelektrika production program - pinion no. 16.920.633 has been analysed. The material of the pinion is 16MnCr5 grade steel (Table 1), produced in Slovenian steelwork Metal Ravne, with well known mechanical and thermal properties.[11] Table 1. Chemical composition of 16MnCr grade steel in mass fraction, w/% w/% Element C Si Mn Cr Cu Al Ni P S Standard [11] 0.14-0.19 <0.40 1.00-1.30 0.80-1.10 <0.035 <0.035 Testing Analysis 1 0.162 0.241 1.192 1.014 0.049 0.033 0.147 0.013 0.026 Charge Analysis 2 0.164 0.247 1.167 1.028 0.044 0.035 0.146 0.014 0.027 Figure 1. Cold formed steel forgings from Figure 2. Device for heat treatment in ISKRA Avtoelektrika production program. ISKRA Avtoelektrika. Testing forging - pinion no. 16.920.633 (below, the second from the left). Experimental Work A device for heat treatment installed in ISKRA Avtoelektrika (Figure 2) is produced by the company CODERE from Switzerland. It consists of four main parts[12]: • gas furnace (with pure and high controlled atmosphere), • primary temperature measuring system (measuring the atmosphere temperature in the furnace), • manipulating system, and • hardening vessel (with mineral oil). For the purpose of temperature measurements[13] of the testing charge a secondary temperature measuring system (Figure 2) consisting from three basic elements[14] has been designed: • even coated Ni-NiCr thermocouples, • data acquisition module ADAM -4018, and • personal computer (with Microsoft Excel program) which recorded the results of the measurements. Figure 3. Positions of the samples in the testing charge. In the frame of our investigation work five testing forgings were bored. Ends (tips) of thermocouples were inserted therein and fixed with wire. Then, in the filling of the basket with the forg-ings, the five testing forgings were put on precisely defined, pre-selected places in the basket (A, B, C, D and E). Their positions are shown in Figure 3. The basket holding the forgings has the form of a cylinder, of dimensions: diameter 780 mm and length 680 mm. The basket can hold approximately 700 forgings, which results in the whole charge mass of some 220 kg, and together with basket approximately 325 kg. The heat treatment in the case given is case hardening which consists of car-burizing and hardening. The prescribed time schedule of the heat treatment process is divided in three phases: • heating, • superheating, and • cooling down (hardening) phase. The first phase is an even heating of the charge up to the temperature 920 °C (the prescribed time of heating ranges from 2 h to 3 h). The time set for superheating of the charge in the furnace at 920 °C is 3.5 h to 5 h. The cooling down phase (hardening) of the whole charge follows in the mineral oil (OLMAKAL Rapid 90) with the initial temperature 80 °C approximately 10 min. For the recording of the temperature measurements results a 3 s time interval was selected. The ambient temperature cca 1.5 m from the furnace was measured in the same time intervals on the sixth measuring channel. Complete results of the temperature measurements performed in the heat treatment of the testing charge of the cold formed steel pinions, and detail of the cooling down phase are shown in Figure 4. The efficiency and quality of the heat treatment was analysed with the use of: • chemical analysis (Table 1), • hardness measurements, • measurements of carbon and sulphur content in the case hardened surface layer, and • metallographic examination methods. Surface hardness of the testing samples was measured with the Rockwell (HRc) method. All measured values were higher than HRc 62 (between HRc 62.5 and 67.1). In the Table 2 are presented the results of the hardness measurements (HV1) through the case hardened surface layer (average values of 10 measurements), and in the Table 3 a carbon and in the Table 4 sulphur content in the case hardened surface layer at different distances from the surface (0.1 mm to 1.0 mm). Figure 4. Temperature measurements - testing charge. Table 2. Hardness through the case hardened surface layer. Sample Hardness (HV1) 0.1 mm 0.2 mm 0.3 mm 0.4 mm 0.5 mm 0.6 mm 0.7 mm 0.8 mm 0.9 mm 1.0 mm A 854 839 838 800 751 684 615 564 524 491 B 846 847 840 824 749 698 630 578 531 498 C 843 805 784 744 658 647 585 548 523 503 D 824 778 740 696 656 602 565 528 509 497 E 861 860 854 827 786 734 669 613 573 534 Table 3. Carbon content in the case hardened surface layer of the samples A, C and E. Sample w/% 0.1 mm 0.2 mm 0.3 mm 0.4 mm 0.5 mm 0.6 mm 0.7 mm 0.8 mm 0.9 mm 1.0 mm A 0.891 0.771 0.745 0.787 0.776 0.744 0.728 0.743 0.724 0.710 C 0.742 0.689 0.658 0.653 0.631 0.569 0.507 0.503 0.448 0.395 E 0.814 0.696 0.683 0.673 0.678 0.599 0.620 0.618 0.630 0.613 Table 4. Sulphur content in the case hardened surface layer of the samples A, C and E. Sample w/% 0.1 mm 0.2 mm 0.3 mm 0.4 mm 0.5 mm 0.6 mm 0.7 mm 0.8 mm 0.9 mm 1.0 mm A 0.072 0.032 0.031 0.032 0.030 0.031 0.031 0.030 0.029 0.026 C 0.052 0.035 0.033 0.028 0.028 0.028 0.028 0.029 0.028 0.028 E 0.057 0.029 0.029 0.028 0.027 0.022 0.021 0.028 0.028 0.027 In the frame of our experimental work also non-destructive metallographic examination by optical microscopy (OM) and scanning electron microscopy (SEM) was applied. In the Figure 5 is the microstructure (martensitic) of the surface layer of the tooth, and the crack through the surface layer at the tooth of the sample D. The crack length is approximately 650 ^.m. Figure 5. Sample D - tooth. Surface layer, crack through the surface layer; magn. 500-times; OM. Conclusions A gas furnaces and devices play important role in the heat treatments of various metal parts for the automotive industry. Their thermo technical characteristics have a great influence on the both: product quality and costs. In our case the efficiency and quality of the heat treatment procedure were analysed with the use of: chemical analysis, micro hardness measurements, measurements of the carbon and sulphur content in the surface layer, and metallographic examination methods. The practical result of the before described heat treatment are cold formed steel pinions with the surface hardness of approximately HRc 65, and the case hardened depth of the surface layer (with hardness higher then HV1 551) approximately 0.7 mm. Figure 6. System for heat treatment after installation of the second device. On the basis of the results of economical studies, supported by engineering work, the installation of the second device (Figure 6) - of the same producer, type and capacity - for the heat treatment was done. References [1] Adamczyk, J., Opiela, M. (2007): Engineering of Forged Products of Micro alloyed Constructional Steels. Journal of Achievements in Materials and Manufacturing Engineering; Vol. 20, No. 1-2, 153-158. [2] Dobrzanski, L. A. (1997): Technical and Economical Issues of Materials Selection. Silesian Technical University, Gliwice. [3] Shercliff, H. R. (2002): Modelling and Selection of Surface Treatments for Steels. Advanced Engineering Materials; Vol. 4, No. 6, p. 397-402. [4] Thelning, E. K. (1984): Steel and its Heat Treatment. Butterworth, London. [10] [5] Liscic, B., Tensi, H. M., Luty, W. (1992): Theory and Technology of Quenching. Springer Verlag, New [11] York. [6] Trzaska, J., Sitek, W., Dobrzanski, L. [12] A. (2007): Selection Method of Steel Grade with Required Hardenability. Journal of Achievements in Materials and Manufacturing Engineering; Vol. 20, No. 1-2, 471-474. [7] RaiC, K. T. (1993): Control of Gas Carburizing by the Diagram Method. [13] Scandinavian Journal of Metallurgy; Vol. 22, No. 1, p. 50-55. [8] Popovic, Z. V., Raic, K. T. (2006): Pecne atmosphere. Savjez inzenjera [14] metalurgije Srbije; Beograd, 2006 (in Serbian). [9] Grabke, H. J. (1998): Carburization. MTI Materials Technology Institute, St. Luis. Totten, G. E., Howes, M. A. H. (1997): Steel Heat Treatment. Marcel Dekker, New York. Jocic, B. (2008) : Steels and Cast Irons. BIO-TOP, d. o. o., Dobja vas. Kosec, B., Brezigar, M., Kosec, G., Bernetic, J., Bizjak, M. (2007): Heat Treatment of Cold Formed Steel Forg-ings for the Automotive Industry. Journal of Achievements in Materials and Manufacturing Engineering; Vol. 22, No. 2, p. 87-90. Michalski, L., Eckersdorf, K., McGhee, J. (1991): Temperature Measurement. John Wiley & Sons, Chichester. Pavlin, F., Kosec, B., Bizjak, M., Fer-folja, M. C. (1999): Temperature Profile Measurements on Wellman Type Annealing Furnace. RMZ - Materials and Geoenvironment; Vol. 46, No. 1, p. 83-87. Optimiranje delovanja glavnih ventilatorjev v času mirovanja jame Optimisation of mine ventilators operation in conditions of stagnation the pit Boris Salobir1, 2 * 1Univerza v Ljubljani, Naravoslovnotehniška fakulteta, Oddelek za geotehnologijo in rudarstvo, Aškerčeva cesta 12, SI-1000 Ljubljana, Slovenija 2PROTOS Inženirski biro, d. o. o., Cesta III, št. 26, SI-3320 Velenje, Slovenija * Korespondenčni avtor. E-mail: protos@siol.net Received: December 01, 2008 Accepted: March 04, 2009 Izvleček: Optimiranje zračenja je postopek, ki obsega predvsem analizo opravljenih meritev v primerjavi z doslej izvedenimi. Pomembno je poznati vse delovne parametre delovanja ventilatorjev in izdatnost plinov v kritičnem območju - v odkopnem polju jame. Nujna je izvedba simulacije zračenja z zmanjševanjem delovanja ventilatorjev do take mere, da začne koncentracija ekshaliranih plinov v odkopnem polju jame naraščati. Ob tem določimo optimalni način razredčenja nevarnih plinov pred začetkom delovnega procesa od-kopavanja premoga. Glavna naloga optimizacije je, da ugotovimo najugodnejši način zmanjševanja delovanja glavnih ventilatorjev v Pesju in v Šoštanju. S tem bi se v dela prostih dneh zmanjšala poraba električne energije za zračenje, hkrati pa bi bilo zagotovljeno ustrezno prezračevanje jamskih prostorov in razplinitev pred zagonom proizvodnje. Abstract: Optimal ventilation is a procedure which includes the analysis of mesurements done in comparison with the known ones. It is important to know all ventilator operational parameters measured in the most critical sectors in the mine, with stationary as well as manual meters. It is necessary to simulate the ventilator reduced operation up to the point when the concentration of mine gases starts to Professional paper increase, and then determine the optimal way of degassing for safety working process. The main task of the optimalization is to determine the best way of reduced ventilator operation in the Pesje and Šoštanj Pits in order to reduce electricity consumption during the days off and then higher ventilation load to degas the face before the work on it begins. Ključne besede: rudarstvo, jamsko pridobivanje, zračenje, optimiranje Key words: mining, underground lignite exploitation, ventilation, optimisation Uvod Prezračevanje v jamah velenjskega premogovnika obratuje nenehno in s stalnimi kapacitetami. Zračilni sistem poganjata dva ventilatorja, in sicer ventilator v Šoštanju s 15 000 m3 zraka v minuti in ventilator v Pesju z 8 000 m3 zraka v minuti. Zračenje, vezano na ventilator v zračilni postaji Pesje, deluje po sistemu diagonalnega zračenja, zračenje dela jame, ki je vezan na ventilator v Šoštanju, pa deluje v enem delu po sistemu diagonalnega, v drugem pa po sistemu centralnega zračenja. Zaradi potrebe po razplinjenju odprtega dela premogovnega sloja, to je zaradi zmanjševanja koncentracije nevarnih plinov, deluje sistem tudi v dela prostih dneh, kar povzroča veliko porabo energije. Ob delovnih dnevih se jama prav tako zrači s polno kapaciteto, saj so ekshalacije nevarnih plinov zelo velike zaradi velikega napredka odkopov, posebej v zadnjem času zaradi tako imenovane »turbo«-proizvodnje. To je pridobivanje premoga iz odkopov s povečano odkopno dolžino, ki lahko dosega tudi več kot 200 m, z velikim napredkom in zelo visoko dnevno proizvodnjo. Premogovnik Velenje v teku delovnega leta večkrat prekine svoje obratovanje za več dni, predvsem iz ekonomskih razlogov. V tem času se zmanjšajo vse aktivnosti na minimum, torej tudi delovanje ventilatorjev. Ker v času mirovanja jame in zmanjšane stopnje prezračevanja vseeno naraščata koncentraciji metana (CH4) in ogljikovega dioksida (CO2), je treba z optimiranjem delovanja glavnih ventilatorjev zagotoviti varno mirovanje jamskih prostorov in varen ponovni zagon proizvodnje v okviru dovoljenih koncentracij jamskih plinov. Tehnično se v jamah Premogovnika Velenje zmanjšanje delovanja glavnih ventilatorjev izvede s spreminjanjem naklona lopatic ventilatorjev. Po podat- kih je možen premik lopatic ventilatorja, ki obratuje v zračilni postaji Pesje v območju od -20° do +2° naklona. Ventilator v zračilni postaji Šoštanj lahko reguliramo v območju od -8° do +10° naklona lopatic, ne da bi se pri tem obratovalna točka ventilatorja kritično spremenila. Tako se zmanjša depresija, ki jo ustvarja ventilator, in s tem pretok zraka skozi jamske prostore ter posledično poraba pogonske (električne) energije. Namen optimiranja Osnovna ideja optimiranja je določiti krivuljo zračenja, s katero bo mogoče organizirati pravočasno (z minimalno časovno zamudo) vklapljanje in izklapljanje glavnih jamskih ventilatorjev s spreminjanjem naklona njihovih lopatic in s tem kapacitete zračenja tako, da bo zračenje energijsko ekonomično in še vedno dovolj varno. Ta zahteva se nanaša predvsem na razredčenje izhajajočih plinov (CO2 in CH4) iz premogo-vega sloja. Glavni namen optimiranja ni ugotavljanje porabe energije ventilatorjev, temveč ugotavljanje učinka zračenja ob doslej uveljavljenem postopku zmanjševanja dotoka zraka v jamske prostore ob dela prostih dneh. Poudarek je na določitvi najzgodnejšega ali najpoznejšega termina zmanjšanja oz. povečanja kapacitete ventilatorja glede na izkazane plinske razmere v zračil- nem območju, ne da bi se s tem poslabšale varnostne razmere. Takšna optimizacija lahko omogoči velik prihranek pogonske energije ventilatorjev, ki so sicer zelo velik energijski porabnik. Glavna usmeritev optimiranja je v zmanjšanju dobavljanja količine zraka v jamski sistem, predvsem ob dela prostih dneh, in s tem tudi ustvarjanja prihranka pri porabi pogonske energije. Ob tem se z meritvami določijo kritična mesta zračenja, največje in najmanj -še potrebne količine zraka glede na ekshalacijo plinov, predpisano hitrost in količino zraka. Izvede se simulacija zračenja pri nižji stopnji obratovanja ventilatorja z upoštevanjem vseh potrebnih varnostih parametrov in določi krivulja zračenja za krajše obdobje ne-obratovanja jame (vikend) in za daljše obdobje (kolektivni dopust, daljši prazniki). Preveri se tudi poraba električne energije in posebej jalova energija ter njena možna izraba. POSTOPEK OPTIMIRANJA IN MERITVE Za izvedbo optimiranja izberemo postopek konkretnih meritev med ustavljanjem obratovanja, mirovanja in ponovnega povečanega zagona ventilatorjev pri zračenju jame po krajši in daljši prekinitvi. Za izvedbo optimiranja ventilatorja, to je prilagajanja novim razmeram, je treba izvesti nasle- dnje meritve: • meritve glavnih zračilnih parametrov (depresija, pretok, hitrost, količina zraka); • meritve plinov in hitrost naraščanja zaplinjenja; • merjenje padca barometrskega tlaka (Ap) in ugotavljanje njegovega vpliva; • merjenje pretoka (q) in merjenje depresije (h); • padec tlaka na etažah; • padec tlaka na etažah pri spremembi naklona lopatic ventilatorja za a = 1° vsak dan; • merjenje obratovalne točke ventilatorja in določitev krivulje zračenja. Navedeni parametri so bistvenega pomena za prilagajanje delovanja ventilatorjev. Operativni del raziskovalne skupine je v jami izvedel meritve v predvidenem času - letni kolektivni dopust in zimski kolektivni dopust ter ob vikendih. Za izvedbo meritev so bili uporabljeni obstoječi stacionarni merilniki, anemometer in aneroidni barometer. Izvedene so bile štiri meritve, dve ob vikendih in dve ob kolektivnem dopustu avgusta in decembra, in sicer v južnem krilu jame Preloge in v jami Pesje ter dodatno še na lokaciji odkopa v severnem krilu jame Preloge. Podatki o ventilatorjih Jama velenjskega premogovnika se zrači z dvema glavnima ventilatorjema. Prvi, tipa Turmag GVhv 34-1800, z na-zivno močjo 1800 kW deluje v zračil-ni postaji Šoštanj in je bil vgrajen leta 1980. Ob njem je enak rezervni ventilator. Drugi ventilator tipa TLT-GAF 34-13, 3-1 z nazivno močjo 800 kW deluje v zračilni postaji Pesje in je letnik 1996. Rezervni ventilator je tipa Turmag GLH-28-660 z močjo 600 kW. Sistem zračenja je naravnan tako, da njuno delovanje medsebojno nima vpliva. Ločena sta v vstopnem zračilnem območju s kratkim stikom. Območje izvedenih meritev torej napajata dva ventilatorja, in sicer eden za jamo Preloge - sever in jug, iz zračilne postaje Šoštanj in eden za jamo Pesje iz zračilne postaje Pesje. V zračilni postaji Šoštanj obratuje glavni jamski ventilator z naslednjimi karakteristikami: Obdelava podatkov delovanja ventilatorjev Splošna obdelava podatkov temelji na analitičnem primerjanju in linearnem statističnem vrednotenju dobljenih rezultatov. Najpomembnejši so trije glavni parametri zračenja (ventilatorja) in sicer: • količina zraka Q/(m3/s) • padec tlaka Ap/Pa • moč motorja P/kW Delovanje ventilatorja v zračilni postaji Šoštanj Količina zraka, ugotovljena iz izvedenih meritev, ki jo daje glavni ventilator v zračilni postaji Šoštanj, je med 190 m3/s Tabela 1. Podatki za glavni ventilator v postaji Šoštanj PODATKI ZA GLAVNI JAMSKI VENTILATOR TIPA TURMAG GVhv 34-1800 v zračilni postaji Šoštanj parameter nižja vrednost višja vrednost nazivna moč/kW 500 1800 depresija/Pa 1800 4600 napetost/kV 6,0 6,3 tok/A 110 160 cos 0 0,61 0,92 naklon lopatici -8 +10 pretok/(m3/s) 160 360 PODATKI ZA GLAVNI JAMSKI VENTILATOR TIPA TURMAG GAF 24/13, 3-1 v zračilni postaji Pesje parameter nižja vrednost višja vrednost nazivna moč/kW 350 800 depresija/Pa 750 3800 napetost/kV 5,9 6,1 tok/A 45 65 cos 0 0,70 0,80 naklon lopatici -20 +4 pretok/(m3/s) 50 200 Vrednosti za posamezne parametre so zaokrožene. V zračilni postaji Pesje obratuje glavni jamski ventilator z naslednjimi karakteristikami: Tabela 2. Podatki za glavni ventilator v postaji Šoštanj in 340 m3/s in kaže padec ob spremembi režima delovanja med mirovanjem jame ter večjo obremenitev ob ponovnem povečanju. Ekvivalenten količini zraka je padec tlaka, ki pada do najnižje točke delovanja in se ob ponovnem povečanju moči spet dvigne. Meritve spreminjanja koncentracije plinov Za nadaljnjo obdelavo sta uporabljena samo ključna parametra jamskega zraka, to sta koncentraciji metana in ogljikovega dioksida v jami Pesje, Preloge - jug in Preloge - sever na merjenih lokacijah. Ustrezno količini dovajanega zraka v jamo in padcu tlaka se spreminja moč motorja ventilatorja, ki ima krivuljo enake oblike kot pri količini zraka in padcu tlaka. Delovanje ventilatorja v zračilni postaji Pesje Rezultati delovanja ventilatorja v zračilni postaji Pesje so podobni tistim v zračilni postaji Šoštanj. Rezultati obratovanja so ekvivalentno izraženi tudi s količino zraka. Podobno kot pri ventilatorju v šoštanj-ski zračilni postaji se tudi pri ventilatorju v Pesju izraža režim obratovanja z močjo motorja, vendar v manjši meri oziroma z manjšim odmikom. Za prikaz merjenih parametrov so vzeti samo najpomembnejši, to so količina zraka, depresija oziroma padec tlaka in moč motorja ventilatorjev. Na odkopih se izvajajo meritve koncentracije plinov s stacionarnimi kon-tinuirnimi merilniki metana in CO2. Meritve koncentracije CH4 in CO2 kažejo podobno spreminjanje vrednosti koncentracij plinov na vseh treh etažah in so v soodvisnosti z merjenimi parametri delovanja glavnih ventilatorjev. Pridobljeni podatki so bili numerično obdelani, na njihovi podlagi pa so bili izdelani ustrezni sklepi. Iz množice meritev so bili uporabljeni samo reprezentativni podatki, ki kažejo shemat-sko sliko dogajanja pri prezračevanju delovišč med mirovanjem jame. Spreminjanje koncentracije metana Spreminjanje koncentracije metana (CH4) poteka v območju od 1,45 % do 1,8 % v izstopnem zračnem toku z delovišč na začetku procesa, nato se ustali za določeno obdobje na višini okrog 0,65 % do 0,8 %. Po preteku 14 dni mirovanja jame začne kon- centracija strmo naraščati in se dvigne na kritično mejo, ko je treba povečati delovanje ventilatorjev. Ta kritični del obsega kratko časovno obdobje in se hitro normalizira. V krajšem časovnem obdobju mirovanja jame, to je preko vikenda, koncentracija metana ne pade pod 1 %, naraščanje pa ne nastopi, saj se zaradi varnostnih ukrepov poženejo ventilatorji pred pričetkom ponovnega obratovanja jame, ki se začne, zaradi kratkega mirovanja, še pred nastankom visoke koncetracije plinov. Spreminjanje koncentracije ogljikovega dioksida Spreminjanje koncentracije ogljikovega dioksida (CO2) je manj intenzivno kot metana. Z vrednosti, ki na začetku dosega od 0,6 % do 0,8 %, se zmanjša na 0,3 % do 0,5 % ter obstane pri teh vrednostih okrog 10 dni. Naraščati začne nekoliko prej kot metan, a ostaja še v dovoljenih mejah koncentracije. Ob izvajanju meritev se vrednost CO2 ni nikoli približala kritični meji. Spreminjanje koncentracije ogljikovega monoksida Spreminjanje koncentracije ogljikovega monoksida (CO) je tesno vezano na količino dotekajočega zraka v jamske prostore in sledi spreminjanju koncentracije metana in ogljikovega dioksida. Pri večji količini zraka se je tudi koncentracija ogljikovega monoksida povečevala in obratno, a nikoli ni dosegla posebej visokih vrednosti. Na merilnih mestih so bile koncentracije med 0 ppm in 10 ppm, le enkrat samkrat je bila izmerjena vrednost 33 ppm. Spreminjanje koncentracije kisika v zraku Vsebnost kisika (O2) v zraku je pokazala dokaj konstantne in normalne vrednosti, ki so bile v volumenskih deležih od 20,3 % do 20,9 %. Izraba moči ventilatorjev Ventilator v zračilni postaji Šoštanj Glavni ventilator v zračilni postaji Šoštanj v normalnih razmerah obratuje s 75 % svoje moči, kar je pri 1375 kW. To je tudi začetna obremenitev ob spreminjanju naklona lopatic in s tem zmanjševanja dotoka zraka v jamo ter s tem razbremenjevanja ventilatorja. Ta lahko pade celo na 48 % svoje vrednosti, kar je 880 kW. Pri povprečni obremenitvi okrog 1150 kW ventilator obratuj e 10 dni pri daljšem časovnem obdobju mirovanja jame in dva dneva pri krajšem obdobju mirovanja, kar pomeni 225 kW h prihranka ali do 75 600 kW h prihranka v času dalj šega (štirinaj stdnevnega) mirovanja jame. Ventilator v zračilni postaji Pesje Glavni ventilator v zračilni postaji Pesje deluje v normalnih razmerah z 58 % moči ali pri 470 kW obremenitve. Zmanj- šanje moči med daljšim mirovanjem jame je sicer le 18 % od delujoče obremenitve in pade na 48 % nazivne moči ventilatorja. Pri povprečni obremenitvi okrog 390 kW obratuje pribl. 10 dni, s čimer je prihranek energije 80 kW h ali 19 200 kW h v celotnem obdobju. V primeru, da jama miruje dalj časa, pa je prihranek še večji. Krivulja prezračevanja jame v dela PROSTIH DNEH Spodnji diagram prikazuje shematsko krivuljo prezračevanja jame v dela prostih dneh - prirejeno za 14-dnevno obdobje mirovanja jame. Krivulja obsega območje in spreminjanja vrednosti metana in ogljikovega dioksida ter ekvivalentno zmanjševanje in povečevanje moči - obratovanja glavnih ven- tilatorjev v zračilnih postajah Šoštanj in Pesje. Krivulja je razdeljena na štiri bistvene dele: • upadni del, kjer zmanjšujemo obratovanje ventilatorja; • uravnoteženi del, ki lahko traja precej časa, glede na razmere v jami; • naraščajoči del, kjer se vrednosti dvigajo, in • stanje normalizacije, kjer se vzpostavi normalno obratovanje ventilatorjev ob ponovnem začetku obratovanja jame. Na diagramu so prikazane najvišje in najnižje začetne in končne vrednosti koncentracij metana, ogljikovega dioksida ter območje spreminjanja vrednosti, hkrati pa sta predstavljeni krivulji obratovalne moči ventilatorjev. Diagram 1. Krivulja prezračevanja jame v dela prostih dneh Ocena optimizacije ventilatorjev Optimiranje obratovanja glavnih ventilatorjev, ki prezračujejo jamo Premogovnika Velenje je v času mirovanja jamskih delovišč privedeno do zelo visoke stopnje, kar je posledica velike skrbi in zavzetosti tako predhodnih kot sedanjih strokovnjakov za zračenje na tem zahtevnem področju. Šoštanjski ventilator ob 2977 Pa depresije in količini 216 m3/s zraka v času zmanjšane aktivnosti že pade v najnižji režim možnega ekonomskega obratovanja. Ventilator v Pesju je ob obratovanju v enakih razmerah pri depresiji 935 Pa in 181 m3/s že močno zunaj ekonomskega obratovanja, primerjalno - moč : depresija : količina zraka : cos 0. Podatki kažejo, da ta dva režima obratovanja ventilatorjev ustrezata plinskim razmeram v jami in sta v skladu z varnostnimi predpisi. Seveda pa je treba upoštevati, da so bili z meritvami zajeti le trije odkopi, druge, oddaljenejše jamske komunikacije pa ne. Povzetek Iz prikazanega prilagajanja obratovalnega režima ventilatorjev med mirovanjem jame ni več možno pričakovati velikih prihrankov, določene omejene, sicer finančno zahtevne možnosti pa so naslednje: opraviti je treba simulacijo hitrega prilagajanja spremembam koncentracije plinov v jami s primerjanjem že dobljenih podatkov kot najenostavnejši način optimizacije; uvesti popolne nadzorne meritve (monitoring) nad delovanjem ventilatorjev in spreminjati njihov režim obratovanja praktično nenehno glede na razmere zaplinjenosti v jami; le s hitrimi spremembami obratovalnega režima ventilatorjev je možno še povečati prihranke pri porabi pogonske energije za 8-9 %; izpopolniti avtomatizacijo delovanja ventilatorjev in prilagajanja krivulji zračenja, kar zagotavlja od človeka neodvisno optimiranje; začeti prilagajati kvaliteto izdelave, preseka, dolžine in povezav jamskih zračilnih vodnikov - prostorov (prog); preveriti izrabo jalove energije, saj se njen faktor (cos 0) precej poslabša ob nižanju moči ventilatorja; izvesti polioptimizacijo celotnega ventilacijskega sistema, ki naj zajema stabilnost zračilnega toka, porabo energije, efektivnosti prezračevanja (faktorja izkoristka zračilnega sistema) in inženirsko strojniške zasnove ventilatorjev (difuzor, paralelno delovanje, mehanske poškodbe, korozijo in erozijo, vibracije in aerodinamične komponente). Podatki za optimizacijo so bili pridobljeni s štirimi meritvami. Meritve so pokazale, da dosedanji način zračenja z zmanjševanjem delovanja glavnih ventilatorjev takoj po prenehanju dela, z zmanjšanim obratovanjem v času prostih dni in s povečanjem delovanja ventilatorjev tik pred nastopom dela po večdnevni prekinitvi za razplinjenje ekshaliranih plinov ustreza zahtevam po varnem delu - razplinjenju. Optimizacija se lahko izvaja, če so urejeni: avtomatsko merjenje koncentracije plinov v jami ali njenih oddelkih, avtomatska regulacija ventilatorjev in avtomatska regulacija ključnih regulacijskih objektov (vrata in dušilke). Ko se začne večati količina metana v kritičnem tokovnem krogu proti 1,4 %, je treba izvesti regulacijo, da na kritični odsek usmerimo večjo količino zraka. Tehnična opremljenost je pogoj za op-timiranje. Ta zahteva daljinsko upravljanje ventilatorjev oziroma daljinsko spreminjanje naklona lopatic ventilatorjev. S tem dosežemo spremembo obratovalne točke ventilatorja in depresije ter spremembo režima obratovanja ventilatorja. Viri [1] Salobir, B. (2004): Optimiranje delovanja glavnega ventilatorja v odvisnosti od izmerjenih parametrov. Program raziskovalne naloge, Premogovnik Velenje, d. d., in Protos, inženirski biro, d. o. o., Velenje. [2] Salobir, B., žibert, Z., Založnik, Z., Biščic, A. (2005): Optimiranje delovanja glavnega ventilatorja v odvisnosti od izmerjenih parametrov. Raziskovalna študija, št. PR0-PV-RS-1/2004, Premogovnik Velenje, d. d., in Protos inženirski biro, d. o. o., Velenje. [3] Salobir, B. (2006): Vaje iz tehničnega rudarstva - zračenje. Univerza v Ljubljani, Naravoslovnotehniška fakulteta, Oddelek za geotehnologijo in rudarstvo, Ljubljana. [4] Žibert, Z.(2006): Določitev zračilnih parametrov po barometrski metodi. Magistrsko delo. Mentor doc. dr. Boris Salobir, Univerza v Ljubljani, Naravo-slovnotehniška fakulteta, Oddelek za geotehnologijo in rudarstvo, Ljubljana. Author's Index, Vol. 56, No. 3 Adesina A. D. Bizjak Milan Bombač David Brezigar Matjaž Budak Igor crnobrnja Branislava čevnik Gabrijela Dolšek Matjaž Fazarinc Matevž Gosar Mateja Hodolič Janko Ilič Milana Kosec Borut Kosec Gorazd KovAčič Miha Miler Miloš Miller Michael D. Muhič T. Nton M. E. Peruš Iztok Pleterski M. PšENičNiK Matej Salobir Boris Shields Deborah J. šolar Slavko V. 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Recenzenta izbere Uredništvo med strokovnjaki, ki so dejavni na sorodnih področjih, kot jih obravnava prispevek. Avtorji lahko sami predlagajo recenzenta, vendar si uredništvo pridržuje pravico, da izbere drugega recenzenta. Recenzent ostane anonimen. Prispevki bodo tudi tehnično ocenjeni in avtorji so dolžni popraviti pomanjkljivosti. Končno odločitev za objavo da glavni in odgovorni urednik. Oblika prispevka Prispevek predložite v tiskanem oštevilčenem izvodu (po možnosti z vključenimi slikami in tabelami) ter na disketi ali CD, lahko pa ga pošljete tudi prek E-maila. Slike in grafe je možno poslati tudi risane na papirju, fotografije naj bodo originalne. Razčlenitev prispevka: Predloga za pisanje članka se nahaja na spletni strani: http://www.rmz-mg.com/predloga.htm Seznam literature je lahko urejen na dva načina: -po abecednem zaporedju prvih avtorjev ali -po [1]vrstnem zaporedju citiranosti v prispevku. Oblika je za oba načina enaka: Članki: Le Borgne, E. (1955): Susceptibilite magnetic anomale du sol superficiel. Annales de Geophysique; Vol. 11, pp. 399-419. Knjige: Roberts, J. L. (1989): Geological structures, MacMillan, London, 250 p. Tekst izpisanega izvoda je lahko pripravljen v kateremkoli urejevalniku. Na disketi, CD ali v elektronskem prenosu pa mora biti v MS Word ali v ASCII obliki. Naslovi slik in tabel naj bodo priloženi posebej. Naslove slik, tabel in celotno besedilo, ki se pojavlja na slikah in tabelah, je potrebno navesti v angleškem in slovenskem jeziku. Slike (ilustracije in fotografije) in tabele morajo biti izvirne in priložene posebej. Njihov položaj v besedilu mora biti jasen iz priloženega kompletnega izvoda. Narejene so lahko na papirju ali pa v računalniški obliki (MS Excel, Corel, Acad). Format elektronskih slik naj bo v EPS, TIF ali JPG obliki z ločljivostjo okrog 300 dpi. Tekst v grafiki naj bo v Times tipografiji. Barvne slike. Objavo barvnih slik sofinancirajo avtorji Označenost poslanega materiala. Izpisan izvod, disketa ali CD morajo biti jasno označeni - vsaj z imenom prvega avtorja, začetkom naslova in datumom izročitve uredništvu RMZ-M&G. Elektronski prenos mora biti pospremljen z jasnim sporočilom in z enakimi podatki kot velja za ostale načine posredovanja. Informacije o RMZ-M&G: urednik prof. dr. Peter Fajfar, univ. dipl. ing. metal. (tel. ++386 1 4250316) ali tajnica Barbara Bohar Bobnar, univ. dipl. ing. geol. (tel. ++386 1 4704630), Aškerčeva 12, 1000 Ljubljana ali na E-mail naslovih: peter.fajfar@ntf.uni-lj.si barbara.bohar@ntf.uni-lj.si Pošiljanje prispevkov. Prispevke pošljite priporočeno na naslov Uredništva: • RMZ-Materials and Geoenvironment Aškerčeva 12, 1000 Ljubljana, Slovenija oziroma jih oddajte v • Recepciji Naravoslovnotehniške fakultete (pritličje) (za RMZ-M&G) Aškerčeva 12, 1000 Ljubljana, Slovenija • Možna je tudi oddaja pri uredniku oziroma pri tajnici. Navodila veljajo od avgusta 2009. TEMPLATE The title of the manuscript should be written in bold letters (Times New Roman, 14, Center) Naslov članka (Times New Roman, 14, Center) Name Surname1, .... , & Name Surnamex (Times New Roman, 12, Center) x University of ..., Faculty of ..., Address., Country ... (Times New Roman, 11, Center) Corresponding author. E-mail: ... (Times New Roman, 11, Center) Abstract (Times New Roman, Normal, 11): The abstract should be concise and should present the aim of the work, essential results and conclusion. It should be typed in font size 11, single-spaced. Except for the first line, the text should be indented from the left margin by 10 mm. The length should not exceed fifteen (15) lines (10 are recommended). Izvleček (Times New Roman, navadno, 11): Kratek izvleček namena članka ter ključnih rezultatov in ugotovitev. Razen prve vrstice naj bo tekst zamaknjen z levega roba za 10 mm. Dolžina naj ne presega petnajst (15) vrstic (10 je priporočeno). Key words: a list of up to 5 key words (3 to 5) that will be useful for indexing or searching. Use the same styling as for abstract. Ključne besede: seznam največ 5 ključnih besed (3-5) za pomoč pri indeksiranju ali iskanju. Uporabite enako obliko kot za izvleček. Introduction (Times New Roman, Bold, 12) Two lines below the keywords begin the introduction. Use Times New Roman, font size 12, Justify alignment. There are two (2) admissible methods of citing references in text: 1. by stating the first author and the year of publication of the reference in the parenthesis at the appropriate place in the text and arranging the reference list in the alphabetic order of first authors; e.g.: "Detailed information about geohistorical development of this zone can be found in: Antonijevic (1957), Grubic (1962), ..." "... the method was described previously (Hoefs, 1996)" 2. by consecutive Arabic numerals in square brackets, superscripted at the appropriate place in the text and arranging the reference list at the end of the text in the like manner; e.g.: "... while the portal was made in Zope environment. [3]" Materials and methods (Times New Roman, Bold, 12) This section describes the available data and procedure of work and therefore provides enough information to allow the interpretation of the results, obtained by the used methods. Results and discussion (Times New Roman, Bold, 12) Tables, figures, pictures, and schemes should be incorporated in the text at the appropriate place and should fit on one page. Break larger schemes and tables into smaller parts to prevent extending over more than one page. Conclusions (Times New Roman, Bold, 12) This paragraph summarizes the results and draws conclusions. Acknowledgements (Times New Roman, Bold, 12, Center - optional) This work was supported by the ****. References (Times New Roman, Bold, 12) In regard to the method used in the text, the styling, punctuation and capitalization should conform to the following: FIRST OPTION - in alphabetical order Casati, P., Jadoul, F., Nicora, A., Marinelli, M., Fantini-Sestini, N. & Fois, E. (1981): Geologia della Valle del'Anisici e dei gruppi M. Popera - Tre Cime di Lavaredo (Dolomiti Orientali). Riv. Ital. Paleont.; Vol. 87, No. 3, pp. 391-400, Milano. Folk, R. L. (1959): Practical petrographic classification of limestones. Amer. Ass. Petrol. Geol. Bull.; Vol. 43, No. 1, pp. 1-38, Tulsa. SECOND OPTION - in numerical order [1] Trcek, B. (2001): Solute transport monitoring in the unsaturated zone of the karst aquifer by natural tracers. Ph. D. Thesis. Ljubljana: University of Ljubljana 2001;125 p. [2] Higashitani, K., Iseri, H., okuhara, K., Hatade, S. (1995): Magnetic Effects on Zeta Potential and Diffusivity of Nonmagnetic Particles. Journal of Colloid and Interface Science, 172, pp. 383-388. Citing the Internet site: CASREACT-Chemical reactions database [online]. Chemical Abstracts Service, 2000, updated 2. 2. 2000 [cited 3. 2. 2000]. Accessible on Internet: http://www.cas.org/ CASFILES/casreact.html. Texts in Slovene (title, abstract and key words) can be written by the author(s) or will be provided by the referee or by the Editorial Board. PREDLOGA ZA SLOVENSKE ČLANKE Naslov članka (Times New Roman, 14, Na sredino) The title of the manuscript should be written in bold letters (Times New Roman, 14, Center) Ime Priimek1, ..., Ime Priimekx (Times New Roman, 12, Na sredino) XUniverza..., Fakulteta., Naslov., Država. (Times New Roman, 11, Na sredino) *Korespondenčni avtor. E-mail: ... (Times New Roman, 11, Na sredino) Izvleček (Times New Roman, Navadno, 11): Kratek izvleček namena članka ter ključnih rezultatov in ugotovitev. Razen prve j bo tekst zamaknjen z levega roba za 10 mm. Dolžina naj ne presega petnajst (15) vrstic (10 je priporočeno). Abstract (Times New Roman, Normal, 11): The abstract should be concise and should present the aim of the work, essential results and conclusion. It should be typed in font size 11, single-spaced. Except for the first line, the text should be indented from the left margin by 10 mm. The length should not exceed fifteen (15) lines (10 are recommended). Ključne besede: seznam največ 5 ključnih besed (3-5) za pomoč pri indeksiranju ali iskanju. Uporabite enako obliko kot za izvleček. Key words: a list of up to 5 key words (3 to 5) that will be useful for indexing or searching. Use the same styling as for abstract. uvod (Times New Roman, Krepko, 12) Dve vrstici pod ključnimi besedami se začne Uvod. Uporabite pisavo Times New Roman, velikost črk 12, z obojestransko poravnavo. Naslovi slik in tabel (vključno z besedilom v slikah) morajo biti v slovenskem jeziku. Slika (Tabela) X. Pripadajoče besedilo k sliki (tabeli) Obstajata dve sprejemljivi metodi navajanja referenc: 1. z navedbo prvega avtorja in letnice objave reference v oklepaju na ustreznem mestu v tekstu in z ureditvijo seznama referenc po abecednem zaporedju prvih avtorjev; npr.: "Detailed information about geohistorical development of this zone can be found in: Antonijevic (1957), Grubic (1962), ..." "... the method was described previously (Hoefs, 1996)" 2. z zaporednimi arabskimi številkami v oglatih oklepajih na ustreznem mestu v tekstu in z ureditvijo seznama referenc v številčnem zaporedju navajanja; npr.; "... while the portal was made in Zope[3] environment." Materiali in metode (Times New Roman, Krepko, 12) Ta del opisuje razpoložljive podatke, metode in način dela ter omogoča zadostno količino informacij, da lahko z opisanimi metodami delo ponovimo. Rezultati in razprava (Times New Roman, Krepko, 12) Tabele, sheme in slike je treba vnesti (z ukazom Insert, ne Paste) v tekst na ustreznem mestu. Večje sheme in tabele je po treba ločiti na manjše dele, da ne presegajo ene strani. Sklepi (Times New Roman, Krepko, 12) Povzetek rezultatov in sklepi. Zahvale (Times New Roman, Krepko, 12, Na sredino - opcija) Izvedbo tega dela je omogočilo......... Viri (Times New Roman, Krepko, 12) Glede na uporabljeno metodo citiranja referenc v tekstu upoštevajte eno od naslednjih oblik: PRVA MOŽNOST (priporočena) - v abecednem zaporedju Casati, P., Jadoul, F., Nicora, A., Marinelli, M., Fantini-Sestini, N. & Fois, E. (1981): Geologia della Valle del'Anisici e dei gruppi M. Popera - Tre Cime di Lavaredo (Dolomiti Orientali). Riv. Ital. Paleont.; Vol. 87, No. 3, pp. 391-400, Milano. Folk, R. L. (1959): Practical petrographic classification of limestones. Amer. Ass. Petrol. Geol. Bull.; Vol. 43, No. 1, pp. 1-38, Tulsa. DRUGA MOŽNOST - v numeričnem zaporedju [1] Trček, B. (2001): Solute transport monitoring in the unsaturated zone of the karst aquifer by natural tracers. Ph. D. Thesis. Ljubljana: University of Ljubljana 2001;125 p. [2] Higashitani, K., Iseri, H., Okuhara, K., Hatade, S. (1995): Magnetic Effects on Zeta Potential and Diffusivity of Nonmagnetic Particles. Journal of Colloid and Interface Science, 172, pp. 383-388. Citiranje spletne strani: CASREACT-Chemical reactions database [online]. Chemical Abstracts Service, 2000, obnovljeno 2. 2. 2000 [citirano 3. 2. 2000]. Dostopno na svetovnem spletu: http://www. cas.org/CASFILES/casreact.html. Znanstveni, pregledni in strokovni članki ter predhodne objave se objavijo v angleškem jeziku. Izjemoma se strokovni članek objavi v slovenskem jeziku. PREMOGOVNIK VELENJE PREMOGOVNIK VELENJE je pomemben in zanesljiv člen v oskrbi Slovenije z električno energijo. Zavedamo se odgovornosti do lastnikov, zaposlenih in okolja. CUT ZA PRIHODNOST Inženirska geologija Hidrogeologija Geomehanika Projektiranje Tehnologije za okolje Svetoval Če se premakne, boste izvedeli prvi Leica Geosystems rešitve za opazovanje premikov Geodetski senzorji samodejni tahimetri. GPS in GNSS senzorji Geotehnični senzorji senzorji nagiba, Campbell datalogger Drugi senzorji meteo, senzorji nivoja Programska oprema za zajem in obdelavo podatkov, analizo opazovanj, alarmiranje, predstavitev rezultatov servis Geoservis. d.o.o. Lil iska cesta <¡5, 1000 l|ut I01I 586 38 30 i-1uvuvv.gec Luti ileiK-vtlBni-O lUlor Jejca Geosystenfs Aškerčeva cesta 1 2 1 000 Ljubljana Telefon: (01) 470 46 08, internetni naslov: E-pošta: omm@ntf.uni-lj.si http://www.ntf.uni-lj.si/