Six coal samples with different densities were obtained from a bituminous coal by float/sink separation.They were subjected to proximate

ultimate analysis as well as thermogravimetric analysis.The effects of density on coal quality and combustion properties were studied.The results indicated that

with an increase in coal density

the contents of volatile matter and fixed carbon decreased

while that of the ash yield increased.The contents of C and N also decreased when the coal density increased.With the increasing coal density

the ignition temperatures of the coal and fixed carbon decreased gradually

and the maximum combustion rate

the maximum exothermic value as well as their corresponding temperatures also decreased.The results showed that the reactivity of the medium-density coal sample was higher than that of the low-density and heavydensity coal samples.