Extraction and separation of chromium from the solution after hydrolysis precipitation of vanadium

Abstract

ABSTRACT The qualified chromium oxide product was prepared successfully using acidic chromium solution after hydrolysis precipitation of vanadium based on sodium salt roasting-water leaching process in high chromium vanadium slag. The reduction conditions of sodium thiosulfate were provided. The influences of various factors on the filtration performance of chromium hydroxide were discussed, including precipitation agents, precipitation modes and precipitation temperature. The effects of chromium hydroxide calcination conditions and washing mode on the quality of chromium oxide were investigated. The results indicated that Na2S2O3 can completely reduce the acidic chromium solution, the reduction pH was less than 4.0, and the mass ratio of Na2S2O3 to Cr(VI) in the solution was 3.1. When the temperature was higher than 60°C, chromium hydroxide obtained by parallel flow precipitation using sodium carbonate as precipitant performed much better in filtration. The washed chromium hydroxide was calcined at 1200°C for 2 h. The final product of Cr2O3 with a purity of 98.76% was obtained after grinding and washing appropriately.