A novel technology for vanadium and chromium recovery from V-Cr-bearing reducing slag

Wastewater produced in the process of vanadium extraction from vanadium slag is treated by reduction and neutralization which produces a V-Cr-bearing reducing slag. The recovery of vanadium and chromium from this slag was investigated by a comprehensive route including sulfuric acid leaching, selective oxidation of low valent vanadium and hydrolysis precipitation of vanadium and chromium. Under the most suitable conditions including a leaching time of 4 h, sulfuric acid addition of 74 wt% and leaching temperature of 90 degrees C, the leaching of vanadium and chromium reached 90.9% and 97.8%, respectively. The vanadium of low valent in leach solution was selectively oxidized by manganese dioxide with the oxidation of 96.9%, while Cr(III) was not oxidized. The hydrolysis precipitation method was used to separate and recover V(V) and Cr(III), and the recovery of vanadium and chromium reached 98.3% and 99.1%, respectively. The overall vanadium and chromium recovery was 86.5% and 96.9%, respectively.