常压下高浓度NaOH浸取铝土矿预脱硅

探讨了常压下高浓度NaOH浸取铝土矿的预脱硅过程中初始NaOH浓度、反应温度、浸出时间和碱矿比等因素对氧化铝、氧化硅浸出率及剩余固相中铝硅比的影响，并得出动力学方程. 结果表明，在50% NaOH溶液、碱矿比2.5及135℃浸出时，反应时间5~20 min内，可使铝土矿铝硅比由7.6提高到12以上，从而满足拜尔法生产氧化铝对铝土矿的品位要求. 用此方法处理铝土矿预脱硅，可以免去物理选矿环节，与其他化学选矿方法相比，具有节能降耗的优点，同时提高铝土矿品位，为中低品位铝土矿的开发利用开辟了一条新途径.

Pre-desiliconization of a Bauxite Ore through Leaching by High Concentration NaOH Solution under Atmospheric Pressure

A leaching process for the pre-desiliconization of bauxite ore by high concentration NaOH solution under the atmospheric pressure was studied. The effects of leaching temperature, initial NaOH concentration, leaching time and mass ratio of alkali to ore on the leaching rates of Al2O3 and SiO2, and the ratio of aluminum to silicon in solid residue were investigated, and the kinetic equation was obtained. The results show that when the mass concentration of NaOH is 50%, the desiliconization temperature 135℃, mass ratio of alkali to ore 2.5 and the desiliconization time about 5~20 min, the ratio of aluminum to silicon of bauxite ore can be increased from 7.6 to 12, so as to meet the grade need of bauxite ore in Bayer process. The pre-desiliconization of bauxite ore can be realized by this process without physical processing. Compared with other chemical processing, the pre-desiliconization treatment can improve the grade of bauxite ore with the advantages of saving energy and reducing production costs, which may provide a new way of exploitation of mid-low grade bauxite ore.