ROASTING PRETREATMENT OF HIGH-SULFUR BAUXITE WITH LOW-MEDIAN GRADE IN CHONGQING CHINA

摘要

High-sulfur bauxite is being paid more and more attention due to the decreasing grade for traditional ore in China. There is rich high-sulfur bauxite with low-median grade in Chongqing, which is being treated with Bayer process with dressing. But there still exist excess impurities of sulfur and iron in the alumina product. The effect of surface density, particle size, temperature and time on the roasting desulfurization process was studied. The optimized roasting conditions are as follows: 750 °C, 60 minutes, the surface density of 7.6 kg/m~2 and the particle size from 147 μm to 177 μm for the ore. Under these conditions, residual sulfur in the roasted ore is lower than 0.4%, which can meet the requirements of alumina production. Meanwhile, the digestion performance of the roasted ore improves. Roasting desulfurization might be one of methods for treating high-sulfur bauxite with low-median grade, and better technical and economic results might be attained when it is used to treat high-sulfur bauxite with organic and/or goethite impurites.