20 KB56 KB19 KB200020242001Labor, MiroslavMartinac, VanjaPetric, Nedjeljkaštevilka:3/4letnik:354 stranistr. 113-116ISSN:1580-2949COBISSID:279391URN:URN:NBN:SI:doc-3BBZK1IJenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijeborov oksidizpiranjekovinski oksidimagnezijev oksidmorska vodausedanjeAn examination of B2O3 in magnesium oxide obtained from seawater| Določanje B2O3 v magnezijevem oksidu iz morske vode|The study has been examining the possibility of a repeated application of the agent used to rinse the precipitate of magnesium hydroxide obtained from seawater by substoichiometric precipitation with the addition of 80% of the stoichiometric quantity of dolomite lime as the precipitation agent. The purpose of the study has been to ensure a high-purity product i.e. magnesium oxide, particularly regarding the B$_{2}$O$_{3}$ content, because the hot-strength properties of certain magnesia refractory products are significantly affected by their boron content. The rinsing agent was alkalized distilled water with a pH=12.5, which was alkalized by the addition of concentrated NaOH prior to each use. The aim of the study was to reduce the amount of magnesium hzdroxide rinsing agent, while retaining satisfactory level of purity for the magnesium oxide product. The product quality was established by determining the concentrations of MgO, CaO and B$_{2}$O$_{3}$ in the calcined magnesium oxide. Examinations were carried out with magnesium oxide samples prepared by rinsing the precipitate with: fresh alkalized distilled water, recycled alkalized distilled water, non-alkalized distilled water and without previous rinsing of the magnesium hydroxide precipitate. The results indicate that by using the recycled alkalized distilled water with a pH=12.5, the B$_{2}$O$_{3}$ content in the MgO samples (80% precipitation) amounts to 0.0807 mass %, which is 58% less than the B$_{2}$O$_{3}$ content in samples prepared without rinsing of the magnesium hzdroxide precipitate (B$_{2}$O$_{3}$ = 0.1937 mass %)Preiskovana je bila možnost večkratne uporabe sredstva za izpiranje usedlin magnezijevega hidroksida, dobljenega iz morske vode z nestehiometričnim načinom usedanja, z dodatkom 80% stehiometrične količine dolomitnega apna kot usedalnega reagenta. Namen postopka je dobivanje čim večje čistote končnega proizvoda, to je magnezijevega oksida, predvsem glede na vsebino B$_{2}$O$_{3}$, ker je lastnost dobljenega magnezijevega oksida za posebne namene, to je visoka trdnost, zelo odvisne od vsebine bora v produktu. Sredstvo za izpiranje je lužnata destilirana voda vrednosti pH 12,5, ki se pred vsako uporabo luži z dodatkom konc. NaOH. Cilj preiskave je varčevanje sredstva za izpiranje usedlin magnezijevega hidroksida pod pogojem, da čistoča končnega proizvoda magnezijevega oksida ustreza zahtevam. Kvaliteta proizvoda se spremlja z določanjem vsebine MgO, CaO in B$_{2}$O$_{3}$ v kalciniranem magnezijevem oksidu. Poskusi so bili narejeni na vzorcih magnezijevega oksida, ki so bili pripravljeni z izpiranjem usedline magnezijevega hidroksida s svežo lužnato destilirano vodo, reciklirano lužnato destilirano vodo ter tudi na vzorcih magnezijevega oksida, ki so bili pripravljeni z izpiranjem z nelužnato destilirano vodo in brez predhodnega izpiranja usedline magnezijevega hidroksida. Rezultati preiskave kažejo, da z uporabo reciklirane lužnate destilirane vode pH=12,5 vsebina B$_{2}$O$_{3}$ v vzorcih MgO(80% usedanje) 0.0807 mas.%, kar je za 58% manj v primerjavi z vsebino B$_{2}$O$_{3}$ v vzorcih, pripravljenih brez izpiranja usedline magnezijevega hidroksida (B$_{2}$O$_{3}$ = 0,1937 mas.%)TEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije