Effectiveness of Hydrothermal Treatment of Coal with Lime for Removal of Trace Elements

The possibility of applying chemical cleaning method to remove trace elements from coal was examined. The hydrothermal reaction with CaO followed by HCl washing was carried out for three different coals. Most of the mineral matter was removed by this treatment, except a small amount of clay and pyrite. The removal percentage of trace elements was generally lower in comparison with that of mineral matter. This is because a substantial portion of trace elements is associated with organic matter or mineral matter that could not be removed by this treatment.