Influence of the Heating Rate on the Quality of Metallurgical Coke

Four bituminous coals of different origins and ranks and one industrial coal blend were carbonized at a semi-pilot scale at various temperatures to study the effect of heat treatment (i.e., different heating rates) on the structural evolution and hence the subsequent reactivity of the resulting cokes and their mechanical strength. The development of the coke microstructural order under different thermal treatments during carbonization was assessed by means of Raman spectroscopy. The results indicated an improvement in the structural order with increased operating temperatures and hence increased heating rates and a decrease in the active sites. The quality of the cokes was determined by means of the Japanese Industrial Standard (JIS) and the Nippon Steel Corporation (NSC) tests. In addition, the apparent reaction rate of cokes was measured using a fixed bed reactor. The increase in the heating rate during carbonization led to cokes with a lower mechanical strength and apparent reaction rate. Good correlation was found between the apparent reactivity of cokes and the coke strength after reaction.