氧化铝熟料溶出二次反应过程SiO_2进入铝酸钠溶液的动力学机理

基于采用较高液固比(20∶1)的实验条件,避免了因硅酸钠与铝酸钠反应形成水合铝硅酸钠(钠硅渣),可将氧化铝熟料溶出二次反应动力学过程分为SiO_2进入铝酸钠溶液和Al_2O_3损失两个动力学过程,详细研究了SiO_2进入铝酸钠溶液过程的动力学行为. 通过选择合适的动力学模型对实验数据进行处理,获得了该过程的动力学方程. 方程表明,该过程的表观活化能较小,仅为24.86kJ·mol~(-1),说明其过程发生需要突破的活化能能垒较小,相应反应较易发生,其动力学机理与表面化学反应有关,也与扩散有关. 铝酸钠溶液中Al_2O_3质量浓度对过程的影响远远大于铝酸钠溶液中Na_2CO_3质量浓度和NaOH质量浓度的影响,因此认为熟料溶出过程中,导致SiO_2进入铝酸钠溶液的原因主要是熟料中的硅酸钙与NaAl(OH)_4相互作用.

Kinetic mechanism of SiO_2 dissolving into sodium aluminate solution in secondary reaction during clinker-leaching

Based on the fact that the formation of sodium aluminium hydrosilicates can be avoided on the experimental condition of high liquid-to-solid ratio (20∶1), the secondary reaction process is divided into two sections according to the characteristics of dynamic process during clinker-leaching. One of the two processes, namely, the process of SiO_2 dissolving into sodium aluminate solution was detailedly researched. Through processing all data with a fitting kinetic model, the corresponding kinetic equation was deduced. The results demonstrate that the process has an apparent activation energy of 24.86kJ·mol~(-1), which serves as an indication that corresponding reactions of this process can easily happen. Since the effect of Al_2O_3 mass concentration in sodium aluminate solution is more than those of Na_2CO_3 mass concentration and NaOH mass concentration greatly, it can be considered that the reaction between calcium silicate in clinker and NaAl(OH)_4 is the main reason to result in SiO_2 entering into sodium aluminate solution.