OXIDATIVE AND IMMERSIONAL HEATING ON LOW RANK COAL SURFACES

The low temperature heating of low rank coal was examined by both differential thermal/thermogravimetric analysis (DTA/TGA) and immersional calorimetry. The effect of surface composition was examined by modifying the oxygen-containing functional groups and the exchangeable metal cation contents. It was seen that a smooth decline in the heat of immersion resulted from a reduction in surface polarity. The heat of immersion was related to a generalized expression that demonstrated the relative contributions of exchangeable metal ion, carboxylic acid and phenolic groups. It was found that brown coats produced highly characteristic heat release profiles on DTA/TGA analysis and that the initial lowest temperature peak and the second exothermic peak could be correlated to the cation content. Removal of a large part of the cations in the high cation Morwell coal transformed it into a coal with a low temperature heating profile almost identical to the low cation Loy Yang coal.