Improved catalyst recovery combined with extracting alumina from Na2CO3-catalyzed gasification ash of a high-aluminium coal char

The catalyst recovery from Na2CO3-catalyzed steam gasification ash of Sunjiahao (SJH) high-aluminium coal char was investigated using water leaching method combined with extracting alumina by means of Ca(OH)2 thermal activation. The recovery efficiency of sodium catalyst from Na2CO3-catalyzed gasification ash (NCGA) with single water leaching method was as low as 39.5 wt%, which resulted from the formation of water insoluble sodium aluminosilicate during Na2CO3-catalyzed gasification. In order to improve sodium recovery, the water-washed NCGA was activated by means of Ca(OH)2 thermal activation for simultaneous recovery of sodium and alumina. The recovery efficiency of sodium from the water insoluble sodium aluminosilicate is 63.6 wt%, thus the total sodium recovery can be remarkably improved and reach 72 wt%. Meanwhile, the extraction efficiency of alumina from NCGA can reach 88.46 wt%. The low sodium recovery with Ca(OH)2 thermal activation is attributed to the formation of Na2CaSiO4 during Ca(OH)2 calcination. Extracting alumina process from NCGA of SJH high-aluminium coal can effectively promote the recovery of sodium catalyst and the process economy.