19 KB146 KB20 KB200020242001Renko, Mijaletnik:35številka:55 stranistr. 265-269ISSN:1580-2949COBISSID:306527URN:URN:NBN:SI:doc-FLU01BL1enInštitut za kovinske materiale in tehnologijeMateriali in tehnologijealuminijaluminumatomska emisijska spektrometrijačiščenjenatrijev hidroksidnevtralizacijaorodjaA novel process for the neutralization of NaOH at an aluminium semimanufactures production facility| Nov nevtralizacijski postopek NaOH pri proizvodnji aluminijevih polizdelkov|During the production of aluminium semifactures on presses there are some tools that must be cleaned because they are covered with aluminium. The tools are soaked in a 20% solution of sodium hydroxide (NaOH) in which the aluminium is dissolved. The tools are then washed with water, which causes a problem because it contains 30-50 mg Al per 1000 ml. There is also a problem with the waste hydroxide, which contains 200 g of NaOH per 1000 ml and 120 g Al per 1000 ml. To avoid environmental polution and the high costs of NaOH regeneration a new way of hydroxide neutralization has been found. The proces is based on the neutralization of NaOH with carbon dioxide (CO$_2$) in the reaction vessel. During this reaction NaHCO$_3$ is formed and the Al is adsorbed onto an added adsorbent. At the bottom of reaction vessel this mix is filtered. The filtered water is clean and can be allowed to flow into the sewage system. The residue is dried and because it is no longer toxic it can be used. Before starting the process of neutralization in production some laboratory tests had to be made first. The chemical composition and the concentrations of input and output substances were determined as well as chemical reactions during the process of neutralization. Determination of the concentrations of input and output substances was made by inductively coupled plasma atomic absorption spectrometry (ICP-AES)Pri proizodnji aluminijevih polizdelkov na stiskalnici je treba očistiti orodja, ki prihajajo v stik z aluminijem. Čiščenje poteka z namakanjem orodij v 20-odstotni raztopini natrijevega hidroksida (NaOH), v kateri se aluminij raztopi. Orodja nato sperejo z vodo. Pri čiščenju nastajajo težave zaradi odpadnega luga, ki vsebuje 200 g NaOH / 1000 ml in 120 g Al / 1000 ml, ter odplak, ki vsebujejo 30-50 mg Al / 1000 ml. Da bi se izognili visokim stroškom regeneracije NaOH in onesnaževanju okolja, so pripravili nov način nevtralizacije luga. Postopek temelji na nevtralizaciji luga z ogljikovim dioksidom (CO$_2$) v reakcijski posodi, kjer nastane natrijev hidrogen karbonat (NaHCO$_3$), aluminij pa se adsorbira na dodanem adsorpcijskem sredstvu. Na dnu reakcijske posode se ta mešanica filtrira. Prečiščena voda je neoporečna in lahko odteče v kanalizacijo. Suhi preostanek se dodatno osuši in ker je okolju prijazen, se lahko uporablja za posipanje cest, v gradbeništvu, itd. Za vpeljavo te vrste nevtralizacije je bilo treba najprej izvesti laboratorijski preizkus ter spoznati kemijsko sestavo in koncentracije vhodnih surovin, kemijske reakcije, ki potekajo med nevtralizacijo in kemijsko sestavo, ter koncentracije izhodnih surovin. Za določevanje koncentracij vhodnih in izhodnih surovin smo uporabili atomsko emisijsko spektrometrijo z induktivno sklopljeno plazmo (ICP-AES)TEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije