Experimental Study On Diffusion Characteristics Of High Orepass Dust Pollution

Driven by the airflow,the dust generated during the high ore pass release process spreads in the chute and the connected roadway,and then is discharged to the surface through the return air shaft,polluting the atmospheric environment and affecting the health of the workers in the stope.In this paper,theoretical analysis,similar experiments and numerical simulations are combined to explore the characteristics of dust pollution diffusion in high ore pass.Through the theoretical analysis of the stress of the ore particles in the high ore pass mine,it is concluded that the main cause of dusting is the airflow caused by the shearing and compression of the ore particles,and the diffusion of dust particles caused by the integrated dusting.The basic formula for the airflow generated in the high ore pass well is obtained,and the factors affecting the airflow are related to the mass flow of the ore,the ore drop height,the size of the ore,the area of the ore pass,and the resistance of the ore pass.According to the formula of airflow generation,based on the similarity theory,the similarity criterion number of high ore pass is derived,and a similar experimental model of high ore pass with 1:10 mid-span is established.The two ores are of different quality,different particle size,different water content,the data were measured under different experimental conditions of continuous resistance and continuous ore-out,and the data were fitted and analyzed.(1): With the increase of the quality of the ore unloading,the wind speed and dust concentration in each middle section are also increasing,and the increasing trend is basically the same.The dust concentration and the maximum wind speed and the high concentration dust duration in the middle of the third stage are larger than other middle sections;(2): The resistance of the ore pass is inversely proportional to the dust concentration and the wind speed value;(3): The smaller the particle size of the ore particles,the more the small particle size dust in the ore particle flow,on the other hand,the larger the contact area between the ore particle flow and the air,the greater the dust concentration and wind speed in the ore pass.(4): The more continuous unloading times,the superposition effect of dust concentration and wind speed in the ore pass,causing large fluctuations in wind speed,dust The sedimentation rate of the particles is low;(5): The higher the ore water content,the more small particle size dust is wetted and agglomerated into large particles,resulting in a smaller dust concentration in the ore pass,but the wind speed remains basically unchanged.;(6): The high grade ore produces less dust than the low grade ore.Based on the high ore pass experimental model,a numerical simulation grid model was established.The DDPM model in FLUENT software was used to simulate the pressure,airflow velocity and ore particle movement and distribution in different masses of high ore pass.Through the analysis of the pressure cloud map,the wind speed cloud map,the particle motion map and the data graph under various experimental conditions,the numerical simulation visually shows the movement state of the ore particles and the flow state of the wind flow.The control of dust diffusion of high ore pass is mainly carried out from pressure,wind flow,water content and other factors.The main form is to construct a channel connecting the top and bottom of the ore pass to conduct pressure relief and pressure at the side of the high ore pass;Water increases the moisture content of the ore particles and radically reduces the generation of dust.