Improving Quality of Coke Made from Chinese Xinjiang Gas Coal with High Strength Modifier

Xinjiang gas coal, one of the Chinese low rank coking coal, was modified by high strength modifier. By measuring final contraction of coke residue index (x), it revealed that Xinjiang gas coal with high x about 38 mm has an adverse effect on coke quality. The coke quality was evaluated by 2 kg coke-oven coking experiment. The results suggested that the coke strength after reaction (CSR) of the coke increased by 21% and the coke reactivity index (CRI) decreased by 18% when 0.5 wt% high strength modifier was added into gas coal. The increase of the diameter of carbon network layer and the decrease of the disordered and unsystematic inherent polycondensation in the Semicoke contraction stage may be responsible for the modified results. The modified mechanism was proposed based on thermo gravimetric (TG) and FTIR spectrometer characterizations of the modified coals, and X-ray diffraction (XRD) analysis of modified cokes.