Caking property and active components of coal based on group component separation

The content and the caking index of the heavy, the dense medium and the loose medium components of coal, obtained by extraction and stripping with CS2[N-methyl-2-pyrrolidinone mixed solvent （1：1 by volume）, were studied and correlated with the caking property of raw coals. Images of the three group com- ponents after heat treatment were analyzed. The results show that both caking index （G） and maximum thickness of plastic layer （Y） of coals have a good linear relationship with the content of the medium component; the dense medium and the loose medium components are the two key factors to determine the caking property of raw coals-they are the source materials of fluidity and swelling of coal, respectively; the heavy component without the swelling and fluidity was cohered by the other components; two new indexes, which can extend current understanding of the caking properties, were introduced.