Co-extraction of vanadium and chromium from vanadium-chromium–bearing reducing slag via oxygen microbubbles intensified copper oxide catalytic oxidation method in alkaline solutions

Vanadium-chromium–bearing reducing slag (VCRS) is a hazardous waste that contains heavy metals like vanadium (V) and chromium (Cr). If not handled properly, it could cause an ecosystem disaster. Here we introduce a new process using copper oxide (CuO) catalytic oxidation intensified by oxygen microbubbles to recover V and Cr from VCRS. Electron paramagnetic resonance (EPR) was used to examine the generation of superoxide radicals (HO2·/O2·-) and their effect on the oxidation of V and Cr. The amount of HO2·/O2·- was directly related to the CuO catalyst and oxygen microbubbles, and the V and Cr oxidative leaching process was dependent on the amount of HO2·/O2·-. We achieved an effective recovery of V and Cr at 110 ºC under atmospheric pressure, and the V and Cr leaching efficiencies were 98.1 % and 98.5 %, respectively, using 50 wt% NaOH solution. This approach is a promising alternative method for the clean treatment of VCRS.