Optimization of Silicon Leaching for White Carbon Black Preparation from Vanadium-Extraction Residue Using Response Surface Methodology

Vanadium-extraction residue (VER) is rich in silicon and the high temperature and high pressure alkali leaching can be used to prepare white carbon black (WCB). The effects of the mass ratio of alkali to slag, liquid-solid ratio, reaction temperature and reaction time on the silica leaching ratio were investigated. Response surface methodology was used to analyze the interaction of these main leaching parameters and the final regression equation can be obtained. By using the regression equation, the leaching schemes can be designed as the maximum leaching ratio of silica was set, thereby the optimal leaching parameters also can be obtained to reduce the leaching cost. Repeated experiments showed that the optimized leaching ratio can reach 95.26% which was just lower the predicted value by 2.17%, indicating that the regression equation was reliable to be used to optimize the leaching process. The WCB product with specific surface area of 105.1 m2/g was verified by XRD and FTIR.