Role of Gas Coal in Directional Regulation of Sulfur during Coal-Blending Coking of High Organic-Sulfur Coking Coal

A high organic-sulfur coking coal and two high-volatile gas coals were selected to partially replace a low-sulfur coking coal in an industrial coal blend. The effects of various coal properties on directional regulation of sulfur during coal blend pyrolysis were investigated by a lab-scale fixed-bed reactor, and the coke quality indices were evaluated by a 10 kg-scale coke oven. After adding gas coals in the coal blend, the experimental sulfur content in coke and sulfur removal were determined to be lower and higher, respectively, than the calculated values, as a result of the directional regulation effect of gas coals on sulfur transformation. Interactions between hydrogen radicals and nascent coke played a more dominant role in sulfur regulation with the addition of the lower ratio of gas coal. The effect of sulfur fixation by minerals deteriorated the sulfur regulation with the further increase of gas coal in the coal blend. These effects were also reflected from the changes of sulfur distribution in coke. The 10 kg-scale coke oven test results showed that adding 7% high-sulfur coking coal and 3% low-ash gas coal into the coal blend could obtain a coke with the quality close to the basic coke, which proved the feasibility of sulfur regulation and indicated that the coking cost would be reduced based on the lower price of the alternative coals than the premium coking coal.