Research on the influencing of heat treatment and coal tar on grindability and floatability of lignite

Due to there is strongly hydrophilic on surface of lignite and thus it is difficult to float with conventional flotation reagents. On the basis of heating treatment of difficult to float lignite,and adding the coal tar during the process of dry grinding of lignite,investigated influence of heat treatment and dry grinding on grindability and floatability of lignite. The results of HGI experiment shows that grindability index of lignite reduced with the decreasing of moisture under the heat treatment condition; HGI index sharply declines when there is more coal tar added. The flotation experiment with coal tar in dry grinding shows that the more the coal tar is added,the lower ash content of clean coal,and the higher combustible material recovery rate. FTIR spectra analysis shows that hydrophobicity of lignite enhanced after the low- temperature heat treatment and adding coal tar.