Extraction of Vanadium from Vanadium Slag Via Non-salt Roasting and Ammonium Oxalate Leaching.

A clean method featuring non-salt roasting followed by (NH)CO leaching to recover vanadium from vanadium slag was proposed. The carcinogenic Cr compounds and exhaust gases were avoided, and the water generated from vanadate precipitation may be recycled and reused in this new leaching process. The leaching residues may be easily used by a blast furnace. Moreover, (NH)CO solution was used as a leaching medium to avoid expensive and complicated ammonium controlling operations as a result of the stability of (NH)CO at a high temperature. The transformation mechanisms of vanadium- and chromium-bearing phases were systematically investigated by x-ray diffraction analysis and scanning electron microscopy with energy-disperse x-ray spectrometry, respectively. In addition, the effects of oxygen concentration, roasting temperature, and holding time on vanadium recovery were investigated. Finally, the effects of leaching variables on the vanadium leaching rate were also examined. [ABSTRACT FROM AUTHOR]