Dust generation characteristics during the wet-mix shotcrete process in mines and the preparation of a composite dust-reducing additive
The dust pollution during the wet-mix shotcrete process in mines constitutes a crucial factor limiting the effi-ciency,cleanliness,and safety of wet-mix shotcrete support projects.To mitigate the potential harm to workers and en-hance the dust control and occupational health capabilities of mines,a dynamic model for the dust generation during wet-mix shotcrete is constructed using the aerosol mechanics and the Hertz-Mindlin collision theory.In consideration of the characteristics of the wet-mix shotcrete process,a similar experimental apparatus for wet-mix shotcrete is established to analyze the dust generation characteristics under different process conditions.Additionally,focusing on the dust reduction mechanism of additives in the wet-mix shotcrete process,a study is conducted on the dust reduction performance of addit-ives,leading to the formulation of a high-performance composite dust-reducing additive suitable for the wet-mix shotcrete process.The results show that the aerosol particles dispersed in the air during the wet-mix shotcrete process predomin-antly have diameters below 2 μm,with particles below 2 μm constituting over 90%of the particle count.Dust generation during wet-mix shotcrete is primarily influenced by factors such as spray distance,spray pressure,and water-cement ratio.The optimal spray distance should avoid extremes,and as the distance increases,the particle concentration shows a trend of initially decreasing and then increasing.Similarly,a spray pressure of 0.4 MPa is deemed suitable,and excessively high pressure leads to an increased rebound rate and dust concentration,while very low pressure results in insufficient kinetic energy for material adhesion to the sprayed surface.Simultaneously,maintaining material fluidity and reducing rebound rates and dust generation can be achieved by lowering the water-cement ratio.The composite dust-reducing additive,com-posed of setting accelerators,chelating agents,early strength agents,binders,and surfactants,is developed.Through ortho-gonal and optimization experiments,the final formula is determined as A-55%,B-3%,C-4.5%,D-0.5%,E-0.15%,and wa-ter-36.85%.Incorporating this composite dust-reducing additive reduces dust concentration during the wet-mix shotcrete process by approximately 57%,effectively lowering dust emissions and demonstrating a significant dust reduction effect.
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维普
