Calculation of emission quantities from different gas emission sources is important to predict gas emission quantity on the horizontally layered working face of a steep seam. However, existing gas emission prediction model has many problems, such as complicated calculation links, poor accuracy and non-applicability to the steep seam. In this study, a model applicable to predict gas emission from horizontal mining layer of steep seam was constructed based on the different-source prediction method. This model was applied to the west wing working face in the 45# seam of WuDong Mine in Xinjiang Autonomous Region in China. Prediction results of this model were compared with existing standard data of the different-source prediction method. According to analysis results, existing different-source prediction model is optimized specifically and the proposed model adds predictions of pressure relief gas emission in coal mass below the mining seam and gas emission in top goaf. The calculated gas emission in the working face presents an error of +8.63% with actual gas emission. This error conforms to the practical situation of horizontal layered mining of steep seam and verified the reliability of the proposed model. Conclusions obtained in this study serve as theoretical references to gas emission prediction in horizontal mining layer of steep seam.

Hydrogen sulphide is a toxic gas often present in coal seams and seriously threatens the lives and health of underground workers in coal mines. In this study, we theoretically modelled hydrogen sulphide generation in extremely thick underground coal mines with the +575 level #45 coal seam of Wudong Coal Mine as an example and obtained the on-site hydrogen sulphide emission pattern and spatial distribution features by combining field measurements and computational fluid dynamics simulation. The results showed that hydrogen sulphide mainly exists in the coal porous system in an adsorbed state. Because hydrogen sulphide has a molecular weight greater than the average molecular weight of air molecules, its concentration decreases with the increase of altitude to the bottom plate. When mining the upper stratified coal stratum, it diffuses widely in the working space; while when mining the lower coal stratum, it mainly concentrates at the bottom of the working face. Based on these analyses, on-site treatments were carried out using mixtures with different concentrations of sodium carbonate and sodium bicarbonate. In addition, different combinations of catalysts as well as type A and type B wetting agents were also tested. Eventually, a neutral KXL-I absorbent was developed, and the process of preinjecting absorbent and spraying absorbent was designed. The results showed that the newly developed KXL-I absorbent has high hydrogen sulphide absorption ability and is suitable for use as an absorbent in Wudong Coal Mine; preinjecting and spraying the absorbent can effectively prevent hydrogen sulphide disasters in the +575 level #45 coal seam in Wudong Coal Mine with the optimal final concentration of 0.9% and the absorption rate of 87% at the shearer of 66.6% at the support. Overall, our study provides valuable information for the prevention and control of hydrogen sulphide disasters in coal mines.

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