煤矸石提铝尾渣水热法制备介孔硅酸钙研究

Preparation of mesoporous calcium silicate with alumina-extracted coal gangue by hydrothermal method

以煤矸石亚熔盐法提铝尾渣为原料,采用水热法脱钠制备介孔硅酸钙。考察了碱浓度、液固比、反应温度和反应时间对终渣氧化钠含量和介孔硅酸钙生成的影响。对提铝尾渣水热反应前后分别做XRF、XRD、SEM和BET分析,结果表明:在反应温度为190℃、碱质量浓度为30 g/L、液固质量比为8时,尾渣氧化钠质量分数可由反应前的19.28%降至0.92%,物相由反应前的硅酸钠钙(NaCaHSiO4)转化为水化硅酸钙[Ca5(OH)2Si6O16·4H2O],其孔径主要分布在2~20 nm。反应符合化学反应过程控制,表观活化能为23.11 kJ/mol。

Mesoporous calcium silicate was prepared by hydrothermal method using alumina-extracted coal gangue by submolten salt as raw material.The effects of NaOH concentration,liquid-solid ratio,reaction temperature and reaction time on content of Na2O in final residue and formation of calcium silicate were studied.The properties of the residues before and after reaction were characterized through XRF、XRD、SEM and BET.Result indicated that the tailing Na2O mass fraction decreased from 19.28% to 0.92% and the main phase transformed from NaCaHSiO4 to Ca5(OH)2Si6O16·4H2O under optimal conditions as follow:reaction temperature of 190℃,NaOH mass concentration of 30 g/L and liquid-solid mass ratio of 8.Result showed that the pore size distribution of the calcium silicate ranged from 2 nm to 20 nm.The formation reaction of calcium silicate,with apparent activation energy of 23.11 kJ/mol,was controlled by the chemical reaction in the initial reaction process.