A Novel Technology to Prepare Sodium Vanadate from V–Cr-Bearing Reducing Slag

A novel process for the extraction of vanadium and preparation of sodium vanadate from V–Cr-bearing reducing slag is proposed. This process involves several steps of washing, alkaline leaching, evaporation crystallization and cooling crystallization. The washing procedure ensures that chloride and sulfate ions can be mostly washed away from V–Cr-bearing reducing slag. Subsequently, vanadium can be extracted by alkaline leaching, the leaching rate of vanadium can reach 98%. During this process, vanadium enters the leaching solution, and chromium continues to accumulate in the leaching residue. Finally, most of Na2SO4 can be removed from the alkaline leaching solution by evaporation crystallization, then the Na3VO4·12H2O can be prepared by cooling crystallization. The filtrate of cooling crystallization can be recycled as the new leaching medium with some new alkali added, which greatly reduces the discharge of alkaline wastewater and makes the whole process more environmentally friendly.