钠钙硅渣常压脱碱同步制备硅酸钙粉体

Dealkalization of sodium calcium silicate residue under atmospheric pressure for preparing calcium silicate powder

以低温低钙烧结法处理赤泥产生的钠钙硅渣为原料,通过常压反应制备了硅酸钙粉体。利用XRD、XRF、PSD、SEM-EDS等检测手段,系统研究了不同反应条件对钠钙硅渣脱碱性能、物相转变和制备硅酸钙粉体的影响规律及其反应机理。结果表明:钠钙硅渣脱碱的最佳工艺条件为反应温度97℃、反应时间4 h、液固比10、苛碱质量浓度60 g/L,此时钠钙硅渣的脱碱率为94.67%,硅酸钙粉体的含水率和堆积密度分别为55.1%和0.31 g/cm^(3)。具有锡箔片状结构的C-S-H(I)型水化硅酸钙凝胶为硅酸钙粉体的主要物相。钠钙硅渣脱碱反应由内扩散控制,反应表观活化能为11.22 kJ/mol。

The calcium silicate powder was prepared by atmospheric-pressure transformation,using sodium calcium silicate slag as raw,which was generated from the treatment of red mud by the low-temperature and lowcalcium sintering method.The effects of different reaction conditions on dealkalization performance,phase transformation,physical properties of calcium silicate powder as well as the corresponding reaction mechanisms were systematically investigated by XRD,XRF,PSD and SEM-EDS methods.The results show that the optimal conditions include temperature of 97℃,action time of 4 h,liquid-solid ratio of 10 mL/g and Nk of 60 g/L,the corresponding dealkalization efficiency of sodium calcium silicate residue is 94.67%,and the moisture content and bulk density of calcium silicate powder are 55.1%and 0.31 g/cm^(3),respectively.The calcium silicate hydrate gel of C-S-H(I)with tinfoil sheet structure is the main phase of calcium silicate powder.The dealkalization process of sodium calcium silicate residue is controlled by the internal diffusion,and the apparent activation energy is 11.22 kJ/mol.