脱硅产物对铝酸钠溶液水解性能影响的研究

Study the effect of desilication products on hydrolysising properties of sodium aluminate solution

随着氧化铝企业竞争的激烈和对节能降耗的要求,拜耳法生产过程中铝酸钠溶液的水解问题备受关注,其中处理三水铝石矿时水解程度更为严重。本文模拟三水铝石矿溶出条件研究了145℃下不同时间形成的脱硅产物及其含量对铝酸钠溶液稳定性的影响规律及其机理。结果表明,145℃脱硅条件下形成的水合铝硅酸钠由无定形沸石、方钠石和沸石组成,随着脱硅时间的延长,脱硅产物的结晶度逐渐增加,沸石的含量逐渐增加,方钠石的含量逐渐降低。提高脱硅产物的结晶度和沸石的含量有利于提高铝酸钠溶液的稳定性。随着脱硅反应时间的延长,铝酸钠溶液添加脱硅产物后的水解反应平衡常数逐渐降低。同时,脱硅产物的生成量越大,拜耳法过程铝酸钠溶液的水解程度越大。

In view of the fierce competition of alumina refineries and higher requirements for energy saving, more concerns have been drawn to the hydroly- sis of sodium aluminate in Bayer process, and it is more serious when treating the gibbsite. The desilication products generated at different time under 145℃, and the effect and mechanism of the contents on the solution stability are studied in the paper via simulating the digestion conditions of gibbsite. The results show that the DSPs generated under 145℃ consists of amorphous zeolite, sodalite and zeolite. As the desilication period is prolonged, the crystallinity gradually increases, at the same time the contents of zeolite and sodalite gradually increase and decrease respectively. The increases improve the stability of sodium aluminate solution. With the extension of reaction time, the hydrolysis equilibrium constants gradually decreases. Meanwhile, the larger amounts of DSP are generated, the higher degree of hydrolysis is taken place in solution.