Structure and combustion characteristics of high inertinite coal demineralized by stepwise chemical methods

A high inertinite coal was chosen and its stepwise demineralization samples were prepared. Their structures and combustion characteristics were researched by proximate and ultimate analyses, N₂-adsorption isotherms, and thermogravimetric analysis methods. The results show that the specific areas and pore volumes reduce and the average pore diameters enlarge when the minerals in coal samples are gradually removed by deionized water, HCl, and HF. The structure of a coal sample is nearly unchanged while they are treated with deionized water and HCl, and their chemical composition changes in a way when they are treated with HF. A small amount of water soluble minerals in coal obstruct and the majority acid soluble minerals promote coal sample combustion. The bigger the specific areas, the higher the coal sample combustion activity. The moderate moisture in coal can promote sample combustion.