(中南大学 冶金与环境学院，长沙 410083)
摘 要: 为缓解我国氧化铝工业存在的铝土矿需求量大与国内铝土矿供应严重不足间的矛盾和粉煤灰大量堆积造成的环境问题，基于粉煤灰还原-氧化焙烧-碱浸实现铝硅分离的全新工艺路线，在已有静态小实验基础上，开展了实验室回转窑动态扩大试验研究。结果表明：在1100 ℃、配料比n(Fe):n(Al):n(C)=1.2:2:1.2、进料量75 g、还原焙烧1 h条件下得到的焙烧熟料，在Na2O浓度为77.5 g/L的NaOH溶液中、液固比为20 mL/g时在130 ℃下溶出60 min，熟料中硅溶出率达92%；在Na2O浓度100 g/L、模数为1.0的硅酸钠溶液中130 ℃溶出2 h，硅溶出率达60%以上，获得模数为2.4的硅酸钠溶液。对比分析物料焙烧过程和熟料溶出前后的形貌、粒度变化情况表明，物料粒度较大和溶液结构变化将导致硅溶出率下降。
关键字: 粉煤灰；方石英；铝酸亚铁；还原焙烧；铝硅分离
（School of Metallurgy and Environment, Central South University, Changsha 410083, China）
Abstract:To alleviate the contradiction between the large bauxite demand and the serious shortage of bauxite supply in China''''s alumina industry and solve the environmental problems caused by the massive accumulation of coal fly ash, the laboratory rotary kiln experimental study was carried out based on the proposed process of coal fly ash reduction-oxidation roasting-alkali leaching through the small static experiments. The results show that the clinker are obtained under the conditions of 1100 ℃, n(Fe):n(Al):n(C)=1.2:2:1.2 of the raw materials, the feeding amount of 75 g and reduction roasting residence of 1 h. When it is dissolved in caustic soda solution with Na2O concentration 77.5 g/L and the liquid-solid ratio of 20 mL/g at 130 ℃ for 60 min, the dissolution rate of silicon can reach 92%. While the sodium silicate solution with Na2O concentration of 100 g/L and modulus of 1.0 was used as the leaching agent, the silicon dissolution rate can reach more than 60% at 130 ℃ for 2 h, and the sodium silicate solution with modulus of 2.4 is obtained. Furthermore, the morphology and particle size changes of the materials during the roasting and dissolution processes were analyzed. The results indicate that the coarse particles and solution structure change will result in the reduction of the dissolution rate of silicon.
Key words: coal fly ash; cristobalite; hercynite; reduction roasting; separation of aluminum and silicon
