Thermal-Gravimetric, Calorimetric and Chemical Analytical Characterisation of Coal

Abstract

Abstract:Coal samples from Morupule colliery in Botswana were characterized by bomb calorimetry, thermal-gravimetric analysis, atomic absorption spectrometry and flame photometry. The average heat of combustion of the coal was found to be 27.3 kJ g -1 ; with a substantial amount of ashes left behind. Thermo-gravimetric analysis showed peaks at 59.40 o C corresponding to loss of surface water, an exothermic peak at 448.54 0 C associated with primary devolatilization in which compounds containing carbon, hydrogen and oxygen are released and finally a second exothermic peak at 682.58 0 C associated with the secondary degasification in which methane and hydrogen are released. 70.4% of the coal was left after heating to 1000 0 C indicating that in its present form, Morupule coal is of low quality but releases plenty of heat on combustion. The determination of the percentage weights of Calcium, Chromium, Copper, Lead, Iron using Atomic Absorption Spectrometry (AAS) and that of Potassium and Sodium using flame photometry showed that Iron (21.0956%) is the dominant inorganic element. The percentage weights of the other elements varied between zero and 7.4301%.