Comparative study of K₂CO₃ and Na₂CO₃ in the process of coal gangue catalytic gasification coupled with aluminum extraction from gasification ash

Coal gangue as the research object of this study, the effects of Na₂CO₃ and K₂CO₃ on the gasification reactivity and the dissolution behavior of Al from catalytic gasification were compared. At the same time, X-ray diffraction (XRD) and thermogravimetric analysis (TGA) were used to analyze the thermal-conversion process of mineral in coal gangue with different catalysts and at different temperatures. The results show that compared with K₂CO₃, Na₂CO₃ can react more easily with the kaolinite in coal gangue to form nepheline, which can achieve effective separation of aluminum and silicon by acid leaching. Moreover, using Na₂CO₃ as catalyst, the Al extraction rate of gasification ash treated by hydrochloric acid can reach 92.3%, while it can only reach 83.7% using K₂CO₃ as catalyst. Therefore, Na₂CO₃ has better selectivity for the coal gangue catalytic gasification coupled with aluminum extraction from gasification ash.