The reaction behaviours of Al2O3 and SiO2 in high alumina coal fly ash under various alkali hydrothermal conditions were studied. The means of XRD, XRF, FTIR and SEM were used to measure the mineral phase and morphology of the solid samples obtained by different alkali hydrothermal treatments as well as the leaching ratio of SiO2 to Al2O3 in alkali solution. The results showed that with the increase of the hydrothermal treating temperature from 75 to 160 °C, phillipsite-Na, zeolite A, zeolite P, and hydroxysodalite were produced sequentially while the mullite and corundum phase still remained. Zeolite P was massively formed at low-alkali concentration and the hydroxysodalite was predominantly obtained at high-alkali concentration. By the dissolution of aluminosilicate glass and the formation of zeolites together, the leaching efficiency of SiO2 can reach 42.13% with the mass ratio of Al2O3/SiO2 up to 2.19:1.%研究高铝粉煤灰中Al2O3与SiO2组分在NaOH碱液中不同水热条件下的反应行为。采用XRD、XRF、SEM、FTIR等测试方法对高铝粉煤灰碱溶液处理前后的物相组成和形貌变化进行表征，得到粉煤灰Al2O3和SiO2组分的溶出率变化规律。结果表明，高铝粉煤灰经75°C到160°C不同温度碱溶液处理后，颗粒表面硅铝玻璃相消失，依次生成钠型沸石、A型沸石、P型沸石及羟基方钠石，所含刚玉及莫来石相未被完全溶解。在低碱浓度溶液中P型沸石为主要生成相，高碱浓度下羟基方钠石为稳定的相。在铝硅玻璃体溶解和沸石相生成两种反应的共同作用下，粉煤灰中SiO2的溶出率可达42.13%，滤渣中Al2O3/SiO2质量比提高到2.19：1.
展开▼
