METHOD OF RECOVERING VANADIUM FROM SLAGS Russian patent published in 1997 - IPC

FIELD: metallurgy; processing of slags. SUBSTANCE: method includes preparation of slag and limestone, their dosage, oxidative baking of blend, low-acid leaching of ashes, filtration of slurry, washing and drying of cake, acid additional recovery of vanadium from cake, water washing and drying of reject sludge, and hydrolytic precipitation of divanadium pentoxide from solutions. According to invention, ratio of summary weight of calcium and manganese oxides to divanadium pentoxide weight is 0.8-1.4. Oxidative baking is carried out at temperature gradually increased from 20-100 to 830-870 C with rate 5-20 C/min. Low-acid leaching is performed in four steps: the first one at 45- 55 C and pH 3.7-4.1; the second at 56-65 C and pH 3.5-3.9; the third at 65-75 C and pH 3.3-3.7; and the fourth at 65-71 C and pH 2.9-3.3. Cake is washed in two steps: first with water at 50-80 C and solids to liquid materials ratio 1:(0.5-1.1) and then with sulfuric acid solution with pH 2.4-2.6 at 20-70 C and solids to liquid materials ratio 1: (0.5-1.1), before each step cake having been pressed and dried to residual moisture 5-20%. Hydrolytic precipitation of divanadium pentoxide is performed in two steps: first at pH 1.7-1.9 and 85-97 C and then at pH 2.0-2.2 and 93- 95 C. EFFECT: enhanced efficiency of process. 4 tbl