Abstract: Some important secondary reactions during alumina sinter leaching have been analyzed thermodynamically, and the behavior of SiO2 in the process also investigated. The results show that 2CaO×SiO2 can exist much more stably in caustic solution than in soda solution and sodium aluminate solution. Only the reaction of 2CaO×SiO2 with Na2CO3 can cause the concentration of SiO2 to rise with increasing leaching temperature. NaAl(OH)4 and Na2CO3 play a much more important role than NaOH in the secondary reactions. With the increasing of free Na2Ok concentration, the concentration of SiO2 decreases gradually. Moreover, the effect of Na2CO3 on dissolution of hydrogarnet in sodium aluminate solution is less than that in soda solution.

Key words: secondary reaction, calcium silicate, hydrogarnet, thermodynamics

摘要： 对烧结法生产氧化铝熟料溶出过程中的主要相关二次反应进行了热力学分析，研究了溶出过程中SiO2的行为. 结果表明，b-2CaO×SiO2在铝酸钠3种溶液成分中的热力学稳定性次序为NaOH>>NaAl(OH)4>Na2CO3，即NaOH非常难以分解2CaO×SiO2，后两者则明显容易得多；提高溶出温度，只有Na2CO3与2CaO×SiO2的作用有助于溶液中SiO2浓度的增加；NaAl(OH)4和Na2CO3对二次反应的发生起重要作用，而NaOH作用较小；增加游离Na2Ok浓度，溶出液中SiO2浓度逐渐降低；铝酸钠溶液体系中的碳酸钠与水化石榴石的作用较弱.

关键词: 二次反应, 原硅酸钙, 水化石榴石, 热力学