Vanadium Extraction Opportunities in Alumina Production and Vanadium Complex Study in Organic Phase

One of the steady vanadium extraction sources is by-products of alumina production. The object of study is circulating solution of alumina production, containing 280 g/dm3 Na2O and 0.40-0.57 g/dm3 V2O5. Vanadium compounds can be extracted from alumina solution by crystalization. It was determined that the fluorine admixture has a considerable influence on crystallization of vanadium compounds. The presence of fluorine admixture decreases the vanadium dissolubility due to the formation of Na7(VO4)2F·19H2O. The physical-chemical analysis of crystallization products showed that the increase of extraction rate for vanadium was due to not only formation of salt containing fluorine, but also because of phosphorus crystallization on its surface. And this fluorine crystallization, in its turn, is the additional source for vanadium crystallization. The vanadic compound is identified as Na7(VO4,PO4)2F·19H2O. Extraction of vanadium (V) from pulp using tributylphosphate (TBP) as extragent enables us to increase the effectiveness of the vanadium extraction and to decrease the amount of wastewater in technological process. Pulp is produced by introducing hydrochloric acid into vanadium by-product. In practice, vanadium is extracted by tributylphosphate from hydrochloric acid solutions. Hydrochloric acid solutions formed in the process of extraction from the pulp are intermediate between solid phase (insoluble part of vanadium product and compounds of impurities) and organic phase. The study presents the findings of physical-chemical analysis of vanadium organic complex extracted by tributylphosphate. Such a complex, with high likelihood, has the form of [H3O+·nH2O·mTBP][VO2Cl2·pTBP·hH2O]−.