A novel CO2-water leaching method for AAEM removal from coal: Suppression of PM formation and release during Zhundong coal combustion

Abstract

Zhundong coalfield is one of the core coalfields in Xinjiang, China. Due to its high alkali and alkaline earth metal (AAEM) contents, large amounts of PM were released during Zhundong coal combustion, causing serious environmental pollution. In this paper, a novel CO2-water leaching method was proposed to suppress the PM formation and release during Zhundong coal combustion. The results showed the CO2-water leaching effectively removed water insoluble minerals from coal, such as Na, Ca, Mg, Cl and S, and significantly reduced the PM formation and release during the Zhundong coal combustion, especially for submicron particle formation and release. The releases of PM1, PM2.5, PM10 were reduced by 29.09%, 22.68% and 18.48%, respectively. The detailed characterizations showed that the significant removal of the easily vaporized elements in the coal by CO2-water leaching, such as Na, Ca, Mg, S and Cl, was an main factor for the suppression of PM formation and release. Besides, after CO2-water leaching, the combustion characteristics of Zhundong coal were promoted. Thus, the CO2-water leaching was a feasible method to inhibit the formation and release of PM during Zhundong coal combustion. Furthermore, since the flue gas from coal-fired power plant can be used as a source of CO2, the CO2-water leaching method provided a new way for the efficient utilization of the coal-fired flue gas.