Study on grindability index of lignite at different drying temperatures

The effect of drying temperature on Hardgrove grindability index(HGI) of lignite is explored with the lignite selected from different regions, and the factors causing the change of HGI are investigated through test on rate of weight loss and thermal discomposition and by scanning electronic microscopic analysis. Test results show that the HGI varies widely due to great rate of loss of weight at the water evaporation stage during the pyrolysic process at different drying temperatures; with the rise of drying temperature and water precipitation, the pores of lignite tend to undergo a structural change to varying extent; and the variation of pore distributions is the root cause leading to the change of HGI at different drying temperatures.