水合硅酸钙与碱反应机理的探讨  

EXPLORATION OF REACTION MECHANISM OF CALCIUM SILICATE HYDRATE IN BASIC SOLUTION

作　　者：刘桂华[1] 李小斌[1] 彭志宏[1] 周秋生[1] 

机构地区：[1]中南大学冶金科学与工程学院,长沙410083

出　　处：《硅酸盐学报》2004年第6期777-780,共4页Journal of The Chinese Ceramic Society

基　　金：国家重点基础研究发展规划(G1999064910);国家自然科学基金(50274076)资助项目。

摘　　要：以氢氧化钙和硅酸钠为原料,按照n(CaO)/n(SiO2)=2在100℃合成了水合硅酸钙,并研究了水合硅酸钙在苛性碱或碳酸钠溶液中的反应规律。结果表明:在苛性碱溶液中水合硅酸钙分解率随反应时间的延长而降低,而随着碱浓度的升高而增大;在碳酸钠溶液中水合硅酸钙分解率随着碱浓度的升高,反应时间的延长或温度的升高而增大。分解率大小的比较表明,水合硅酸钙在苛性碱溶液中的稳定性明显大于dηSiO2为水合在碳酸钠溶液中的稳定性。水合硅酸钙在碳酸钠溶液中宏观反应动力学方程可表示为RT[CO32-]1.12,其中:ηSiO2dt=300.97e-30353.76硅酸钙的分解率,t为时间,T为温度。由于表观活化能值较小,因此反应机理不仅与化学反应有关,而且可能也与扩散有关。物相分析结果表明:合成的水合硅酸钙主要以Ca5(SiO4)2(OH)2和Ca5(OH)2Si6O16·4H2O形式存在,与苛性碱反应后,物相未发生明显变化;与碳酸钠溶液反应后,Ca5(OH)2Si6O16·4H2O更容易被分解。According to the molar ratio of n(CaO)/n(SiO2)=2, using calcium hydroxide and sodium silicate as raw materials, calcium silicate hydrate was synthesized at 100°C. The reaction rule of calcium silicate hydrate in soda solution and caustic solution was investigated. The results show that when calcium silicate hydrate react with caustic solution, the decomposition ratio of calcium silicate hydrate is increased with the increase of caustic concentration and the prolongation of reaction time; and in soda solution, the decomposition ratio of calcium silicate hydrate increases with the increase of soda concentration, reaction time and reaction temperature. The comparison on decomposition ratio in different solution indicate that calcium hydrate silicate is unstable in soda solution. The kinetic equation of calcium silicate hydrate reacted with soda solution is obtained. Due to the small apparent active energy, reaction mechanism relates to not only chemical reaction but also diffusion. The results from XRD analysis show that calcium silicate hydrate mainly exist in the form of Ca5(SiO4)2(OH)2 and Ca5(OH)2Si6O16 &middot4H2O, both appear stable in caustic solution but Ca5(OH)2Si6O16 &middot4H2O is easy to be decomposed in soda solution.

关 键 词：水合硅酸钙 苛性碱 碳酸钠 反应机理 

分 类 号：TF82[冶金工程—有色金属冶金]