Optimization of Roasting Additive for Vanadium Extraction Process
摘要
To develop an optimal roasting additive for vanadium extraction, the mixing ratio of sodium carbonate (Na2CO3) and sodium sulfate (Na2SO4) was varied at a fixed temperature of 1373 K. The effect of Na2CO3 concentration on the leaching efficiency of vanadium was studied at a fixed concentration of Na2SO4. The leaching efficiency of vanadium increased when 10 wt pct Na2CO3 was added. However, as the Na2CO3 concentration increased beyond 20 wt pct, the leaching efficiency of vanadium decreased. The effect of Na2CO3 on the leaching efficiency of vanadium was evaluated via X-ray diffraction analysis. As the Na2CO3 concentration increased, the formation of a slag phase prevented the reaction between the SO2 or SO3 gas and vanadium in the vanadium titanomagnetite ore. Na2SO4 did not play a role in vanadium extraction when > 20 wt pct Na2CO3 was added. The leaching efficiencies of other impurities (Al, Si, and Na) were also investigated under various mixing ratios of Na2CO3 and Na2SO4. Compared with the case where only the roasting additive was used, higher leaching efficiencies of Al, Si, and Na were observed. Through thermodynamic considerations, the formation of the dominant phases for Al, Si, and Na leaching was investigated. In this study, the optimal mixing ratio of the roasting additive in the V extraction process was determined to be 10 wt pct Na2CO3 and 5 wt pct Na2SO4 at a roasting temperature of 1373 K.