Comparison of leaching behaviors of aluminum in ash from combustion and catalytic gasification

The leaching behaviors of aluminum in ash from combustion and catalytic gasification, and effects of Na2CO3 addition (0-15%), temperature (600-1000°C) on Al leaching behaviors and mineral composition were investigated. The compositions of ash from combustion and gasification, and acid leaching residue were investigated by XRD. The results show that the combustion ash is predominantly composed of mullite, while that from catalytic gasification is sodium aluminum silicate ((Na2O)0.33NaAlSiO4). The Al extraction yield of combustion ash only reaches 40% at leaching conditions of 6 mol/L H2SO4, 60°C and 30 min, while that of catalytic gasification ash with 10% Na2CO3 addition can reach 88%. The catalytic gasification with Na2CO3 addition can achieve higher Al extraction yield.