Experimental study on conversion path of sulfur in coal slime preheating combustion

In this study, coal slime was mainly utilized to conduct experiments on a 30 kW preheating combustion test rig to analyze the conversion pathway of sulfur during the experiment, aiming at reducing slime pollution, controlling sulfur emission reasonably, and providing theoretical support for the preheating combustion technology. The results showed that after the coal slime was preheated, a large number of elements were released. The maximum release rates for H and S were 94.0% and 73.3%, respectively. The released S was converted into the sulfur-containing gases like H2S, COS, CS2, and the rest existed in the solid in the five forms of mercaptan, thiophene, sulfoxide, sulfone, and sulfate. Besides, during the combustion process, the gas was oxidized continuously and finally converted into SO2, leaving only the sulfate in the fly ash. In the preheating combustion process, 26.7% of the S was released from the coal, 73.3% of the S was retained in the semi-coke, and the final SO2 emission concentration of combustion was 959 ppm.