METHOD FOR PRODUCING TRIVALENT AND TETRAVALENT MIXTURE VANADIUM COMPOUND AND METHOD FOR PRODUCING VANADIUM- BASE ELECTROLYTIC SOLUTION

摘要

PROBLEM TO BE SOLVED: To provide a method to produce a trivalent and tetravalent mixture vanadium compound having excellent solubility in sulfuric acid at a time from a tetra or pentavalent vanadium compund by using a reducing agent, and to provide a method for preparing a vanadium-base electrolytic solution. SOLUTION: A vanadium compound essentially comprising a pentavalent vanadium compound is kneaded with 0.35 to 0.4 mol sulfur and 1.2 to 1.9 mol concentrated sulfuric acid to one mole of the vanadium atom in the vanadium compound into a paste state. The pasty mixture is calcined at >=150 deg.C and <440 deg.C to obtain a trivalent and tetravalent mixture vanadium compound. Then the trivalent and tetravalent mixture vanadium compound is dissolved in an aqueous solution of sulfuric acid to obtain a redox flow electrolytic solution.