Analysis of Hydrometallurgical Methods for Obtaining Vanadium Concentrates from the Waste by Chemical Production of Vanadium Pentoxide.

The paper describes hydrometallurgical methods to recycle wastes of vanadium pentoxide chemical fabrication. Sludges containing a significant amount of VO can be considered as an additional source of raw materials for vanadium production. We studied the one-stage leaching method using various iron-based reductants for converting V to V in a solution allowing to precipitate V when its concentration in the solution is low. As a result of the reduction leaching with further precipitation, we obtained concentrates with VO content of 22-26% and a high amount of harmful impurities. Multistage counterflow leaching can be used to fabricate solutions with vanadium pentoxide concentration suitable for vanadium precipitation by hydrolysis and adding ammonium salts. The solutions with VO content of ≈15 g/L can be obtained from the initial sludge by three-stage counterflow vanadium leaching. A concentrate with a content of 78 wt% VO can be precipitated from these solutions at pH = 2.4 by adding ammonium chloride. Additionally, concentrate with VO content of ≈94 wt% was precipitated from the solution with a concentration of >20 g/L VO obtained from the roasted sludge. The concentrates were purified for increasing the vanadium content to 5-7%. The consumption and technological parameters of the considered processes are presented in the paper.