高硫高硅铝土矿焙烧–溶出性能研究

采用悬浮焙烧对高硫高硅铝土矿进行处理，考察了不同焙烧温度对矿石中硫含量的影响，通过X射线衍射和扫描电子显微镜分析了不同温度条件下焙烧对铝土矿中物相变化及微观形貌的影响，研究了焙烧温度对矿石中氧化铝溶出性能的影响。结果表明，悬浮焙烧温度600℃及以上时，能够使铝土矿硫化型硫含量降至0.2wt%以下。焙烧使铝土矿中高岭石相发生分解生成非晶态的偏高岭石，同时破坏矿颗粒致密结构，出现晶粒细化，但温度过高(650℃)会出现局部烧结现象。焙烧使一水硬铝石晶体破坏而活化，600℃时晶体破坏最完全，使600℃焙烧矿在相同溶出条件下溶出效果较原矿及其他焙烧矿优势明显，在溶出温度270℃、苛碱浓度245 g/L、石灰添加量14wt%的条件下，相对溶出率能达96%以上。

Study of roasting-dissolving performance of high-sulfur and high-silicon bauxite

The suspension roasting of bauxite can not only effectively desulfurize, but it can also improve the dissolution properties of low-grade bauxite. Furthermore, it provides a good solution for the industrial utilization of low-grade bauxite with high sulfur and high silicon. In this study, suspension roasting was used to treat high-sulfur and high-silicon bauxite, and the effects of different roasting temperatures on sulfur content were investigated. The effects of roasting on phase transition and microstructure of bauxite were analyzed via XRD and SEM. At the same time, the effect of different calcination temperatures on the solubility of alumina was also studied via dissolution tests. The results showed that suspension roasting desulfurization was feasible. Indeed, the sulfur in bauxite was removed at 550, 600 and 650℃, and the sulfur content in bauxite was reduced to less than 0.2wt% when the suspension roasting temperature was 600℃ or above. As shown by the XRD spectrum, the kaolinite phase in the bauxite was decomposed to form amorphous metakaolin via roasting, and when the roasting temperature reached 600℃ or above, the kaolinite phase was found to be completely decomposed. Furthermore, SEM images indicate that, when the roasting temperature was 600℃, the dense structure of the ore particles was seriously damaged, resulting in grain refinement. On the other hand, local sintering occurred when the temperature reached 650℃. In addition, the diaspore crystal was destroyed by roasting, and the diaspore was activated. In particular, the crystal destruction was found to be most extensive under 600℃ roasting conditions. Thus, the effect of alumina dissolution under the same dissolution conditions was more pronounced than that of row ores and roasting ores at other temperatures. The optimum dissolution conditions were found to be: dissolution temperature of 270℃, caustic concentration of 245 g/L, lime addition of 14wt%, and dissolution rate of 96% or above, which met the requirements of industrial utilization.