Pressure acid leaching of black shale for extraction of vanadium
(Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology,
Kunming 650093, China)
Kunming 650093, China)
Abstract: Extraction of vanadium from black shale was attempted in pressure acid leaching. The chemical components of the sample obtained from Guizhou Province of China show that it contains 3.258% V2O5, 52.880% SiO2 and 16.140% Al2O3. Phase analyses of vanadium indicates vanadium mainly exists in the free oxide and mica. Vanadium contents in the two phases are 18% and 53%, respectively. The contents of V3+, V4+ and V5+ are almost equal. Under the optimum parameters of one-step leaching (reaction time of 3 h, sulfuric addition of 25%, temperature of 150 ℃, liquid to solid ratio of 1.2 mL/g, catalyst (FeSO4) addition of 5% and size of 85% particle 0.074 mm), about 77% of vanadium is recovered. After two-step countercurrent leaching, the leach recovery of vanadium can reach above 90%. Air replacing oxygen is completely feasible. The impurity metals can dissolve into solution in different degrees.
Key words: pressure acid leaching; black shale; vanadium; catalyst