Experimental Research On Coal Mine Spray Dust Reduction Technology Based On EMI

As the main energy source in China,coal is prone to produce a large amount of coal dust during the mining process,which will not only make workers suffer from pneumoconiosis,but also cause coal dust explosion when the concentration of coal dust and other parameters reach certain conditions,which will pose a serious threat to the safe production of the mine.Therefore,reducing the coal dust concentration in the coal mining process is very necessary to improve the underground working environment,ensure the safe production of the mine and the health and safety of workers.In this paper,through theoretical analysis and experimental testing,the influence of physical and chemical structure of different sizes of coal dust on the wettability of coal dust was studied,and the influence of different concentrations of green environmental protection and efficiency biological dust reducer(EMI)solution on the wettability of different particle size coal dust was studied.The mechanism of EMI dust reducing agent for wetting coal dust was analyzed.And under laboratory conditions,the spray dust reduction experiment was carried out on the EMI solution,and the optimal process parameters of EMI spray dust reduction were obtained.The physicochemical characteristics of coal dust with different particle sizes were tested by scanning electron microscopy,specific surface area and average pore size test,and infrared spectroscopy test.And by testing the contact angle between the coal dust and pure water and the moisture absorption of the coal dust,the microscopic factors that affect the wetting of the coal dust are obtained.The results show that the smaller the particle size of coal dust,the larger the contact angle with pure water,the lower the moisture absorption,and the more difficult to wet the coal dust.As the particle size of coal dust decreases,the surface of coal dust tends to be smooth,the specific surface area and total pore volume increase,and the content of oxygen-containing functional groups and hydrophilic groups such as hydroxyl groups in coal decreases,making coal dust difficult to wet.The specific surface area and total pore volume of coal dust as well as the content of hydroxyl groups are the main factors affecting the wetting of coal dust.Through surface tension experiment,contact angle experiment,sedimentation experiment and capillary upward penetration experiment,the wetting effect of EMI on coal dust with different particle sizes is tested.The results showed that when the concentration of EMI solution is 0.6%,the surface tension value of the solution is the lowest,and stable micelles are formed in the solution with the increase of concentration.The contact angle of coal dust decreases with the increase of EMI solution concentration.160 mesh coal samples reach the complete wetting state at 6.0%,200 mesh and 300 mesh coal samples reach the complete wetting state at 8.0%,and 400 mesh coal samples do not reach the complete wetting state at 8.0%.With the increase of EMI solution concentration,the settling time of coal dust decreases and the moisture absorption increases gradually.The water retention of coal dust increases with the increase of EMI solution concentration,and the water retention rates of 6.0%and 8.0%solutions for 160,200 and 300 mesh coal samples are better,and the hardenability of coal samples after water loss is greater.Through the analysis of the EMI wetting coal dust mechanism is mainly divided into four roles:①Reducing the surface tension of water.②EMI molecules adsorb on the surface of coal dust to form EMI adsorption layer,which transforms the surface of coal dust from low energy to high energy,and enhances the wettability of coal dust.③The friction resistance of EMI molecules in micropores on the surface of coal dust increases and reduces water loss.④EMI molecules are adsorbed on the surface of coal dust to improve the evaporation resistance of the solution.Through spray dust reduction experiments,the dust reduction rate of EMI solution on coal dust is generally improved,and the greater the concentration of EMI solution,the higher the dust reduction efficiency,and the best dust reduction effect on respiratory dust.The dust reduction effect of coal dust is enhanced with the increase of spray volume.Through comprehensive analysis,the optimal process parameters for EMI spray dust reduction are determined.