矿井湿喷过程的产尘特性和复合降尘外加剂的制备

Dust generation characteristics during the wet-mix shotcrete process in mines and the preparation of a composite dust-reducing additive

矿井湿喷过程的粉尘污染是制约湿喷支护工程高效、清洁和安全生产的重要因素。为降低湿喷过程粉尘对作业人员的危害,提高矿山企业粉尘防治和职业健康保障的能力,运用气溶胶力学与HertzMindlin碰撞理论,构建了湿喷混凝土冲击产尘的动力学模型;并针对湿喷工艺特点,建立了湿喷混凝土相似实验装置,对不同工艺条件下的产尘特性进行分析;结合湿喷过程外加剂的降尘机制,对外加剂的减弹降尘性能进行研究,配置适用于湿喷工艺的高性能复合降尘外加剂。结果表明,湿喷过程中弥散在空气中的气溶胶颗粒粒径大部分在2μm以下,2μm以下(不含2μm)颗粒数占比在90%以上。湿喷产尘主要受喷射距离、喷射压力和水灰比影响。喷射距离不宜太大或太小;随着喷射距离的增加,颗粒浓度呈先降低后增加的趋势。同样,喷射压力为0.4 MPa时,较为合适。当压力太大时,会导致回弹率和粉尘质量浓度增加;当压力太小时,物料到达受喷面时的动能较小,不能很好地黏附在受喷面。同时,在保证物料流动性的同时,可通过减小水灰比来降低回弹率和产尘量。研制的复合降尘外加剂主要由速凝剂、络合剂、早强剂、黏结剂以及表面活性剂复配形成。通过正交实验以及优化实验,最终确定的湿喷复合降尘外加剂配方及其质量分数为:A-55%、B-3%、C-4.5%、D-0.5%、E-0.15%、水-36.85%。掺入该复合降尘外加剂后,湿喷过程粉尘质量浓度下降了约57%,有效降低湿喷过程的粉尘产生量,降尘效果明显。

The dust pollution during the wet-mix shotcrete process in mines constitutes a crucial factor limiting the efficiency,cleanliness,and safety of wet-mix shotcrete support projects.To mitigate the potential harm to workers and enhance the dust control and occupational health capabilities of mines,a dynamic model for the dust generation during wetmix 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 2μm,with particles below 2μm 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.