从高苛性比铝酸钠溶液中制取氢氧化铝的实验研究

霞石经高压水化学法处理,得到高苛性比铝酸钠溶液加入CaO,生成水合铝酸三钙,溶解于碳酸氢钠溶液中,得到低苛性比铝酸钠溶液,经除杂碳分后,可制得符合国家二级标准(GB/T4294—1997)的氢氧化铝制品。实验结果表明,在水合铝酸三钙形成过程中,影响因素大小的顺序为:CaO/Al2O3>温度>时间;在氧化铝溶出过程中,影响因素大小的顺序为:温度>时间>碳酸氢钠加入量。实验所采用的工艺路线,对于解决从高硅原料中提取氧化铝的问题,具有重要的意义和实际应用价值。

An experimental study of extracting aluminum hydroxide from high caustic sodium aluminate solution

The high caustic ratio sodium aluminate solution can be obtained from nepheline treated by high pressure hydrochemical process.Tricalcium hydroaluminate can be achieved by adding CaO into the sodium aluminate solution.Tricalcium hydoraluminate dissolved in the sodium bicarbonate solution and then obtained low caustic ratio sodium aluminate solution.The as-achieved aluminium hydroxide accords with the China national standard(GB/T 4294—1997)of class 2.The results shows that in the process of precipitation of tricalcium hydroaluminate,the effective order is:CaO/Al2O3 ratio>temperature>time.In the process of alumina extraction from tricalcium hydroaluminate,the effective order is:temperature>time>amount of sodium bicarbonate.This research has significant reference value for extracting alumina from high silicon raw materials.