Abstract: The dissolution behavior of aluminum and silicon from high-alumina coal gangue of HCl and NaOH solutions were investigated classify under the condition of thermal activation.The sample of coal gangue was characterized by X-ray diffrac tion（XRD），scanning electron microscopy（SEM） and surface area measurement（BET）.By using orthogonal experiment，The effect of reaction temperature，reaction time，initial concentration of HCl and NaOH，and solid liquid ratio on the leaching rate of Al2O3 and the dissolution rate of SiO2 as acid leaching residue from high alumina coal gangue treated by thermal acti vation process was analyzed.The results of the process of acid leaching extraction of Al2O3 showed that the order of the influ ence of reaction conditions on the dissolution rate of Al2O3 were solid liquid ratio and reaction time．The optimal process con ditions were as follows: the initial mass fraction of HCl was 20%，the acidleaching temperature was 90 ℃，the acidleaching time was 2.5 h and the solidliquid mass ratio was 1∶6.Under the conditions，the leaching rate of Al2O3 reached 82.95%．The results of the process of alkali solution extraction of SiO2 showed that the order of the optimal process conditions were as fol lows：the alkalidissolution temperature was 95 ℃，the alkali dissolution time was 2 h、the mass fraction of NaOH was 20% and the solid liquid ratio was 1∶10.Under the conditions，the SiO2 dissolution rate reached 69.74%．The order of the influence of reaction conditions on the dissolution rate of SiO2 was：alkali dissolutio temperature and sodium hydroxide concentration.

Key words: high alumina coal gangue；alumina；silica；sequential extraction