Simultaneous Extraction of Vanadium and Chromium from Vanadium-chromium Slag by Sodium Roasting

Based on the theoretical analysis and thermodynamic calculations of chemical reactions for sodium roasting of vanadium-chromium slag,the simultaneous extraction of vanadium and chromium by high sodium and low temperature roasting was proposed.The effects of particle size of vanadium chromium slag,addition amount of sodium carbonate,roasting temperature and time on leaching rates of vanadium and chromium were researched.The results show that a rate of 98.31% and 93.53% respectively for vanadium and chromium leaching can be obtained at the optimum conditions for sodium roasting,i.e.less than 0.074 mm of the particle size of vanadium chromium slag,50%～53% of sodium carbonate addition,60～70 min of the roasting time and 790～850 ℃ of the roasting temperature.After sodium roasting,the phases of V-Cr-Fe spinel,iron olivine and glassy in vanadium-chromium slag disappear basically,mainly with the new phases of sodium vanadates,sodium chromates,sodium pyroxene and Fe₂O₃ formed.