Study on the synergistic control effect of composite reagent water spray on gas and coal dust

Gas and coal dust, as potentially hazardous substances (PHSs) produced during mining, are considered two serious threats to safe mining and the health of miners because of their explosive and pathogenic properties. To address this issue, compound reagents enhanced water spraying technology was used to control the gas and coal dust at the excavation working face in this study, and a spray testing platform and wind tunnel were used to investigate the suppression effect on gas and coal dust. In addition, sink tests and agglomeration experiments were also used to analyse its suppression mechanism. Test results show that the dust reduction efficiencies of compound reagents enhanced water spraying technology for four different particle sizes were 80.00%, 91.43%, 94.74% and 94.46%, and improved by 14.00%, 10.86%, 8.42% and 4.25% compared with water spraying. Moreover, the gas suppression efficiency was also improved by more than 20%. Sink test and agglomeration experiment results show that compound reagent improves the spreading efficiency of the liquid on the surface of the coal by changing its wettability, and this process not only slow down the desorption rate of gas by forming a water-sealing effect on the coal surface indicated, but also promotes the agglomeration of fine-grained coal dust.