中國有色金屬學報(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 25 No. 6 June 2015 |
（1. School of Materials Science and Technology, China University of Geosciences, Beijing 100083, China;
2. Blue Sky Technology Corporation, Beijing 100083, China）
Abstract: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.
Key words: high alumina coal fly ash; Al2O3; SiO2; alkali hydrothermal treatment; reaction behaviour
