Research On The Law Of Coal Body Fragmentation And Dust Fragmentation And Dust Generation In Fully Mechanized Excavation Face

With the continuous improvement of the underground mechanization level,the dust concentration of comprehensive excavation is also increasing.Excessive dust concentration poses a great threat to the life,health and safety of underground workers Different mining areas have different characteristics of dust generation due to crushing and dust generation.It is necessary to formulate specific dust prevention and protection measures to reduce the occurrence of protection redundancy or poor dust prevention effects.Therefore,studying the characteristics of coal body crushing and dust generation in fully mechanized excavation faces is of great significance to improving the safety production management of mining areas and scientifically formulating dust control measures.This article takes the cutting part of the roadheader as the research object,and adopts a combination of theoretical analysis,laboratory experiment and numerical simulation.First,the coal breaking theory and similarity theory of pi-k-shaped picks are studied,the contact model between the pick and the coal body,the force state and load calculation formula of the single tooth and the cutting head are explored,and the basic principles of the similarity theory The introduction is made to provide a theoretical basis for the design of the cutting and crushing dust production test bench Then,according to the actual parameters of the cutting part of the roadheader,combined with the coal breaking demand of the test platform and similar proportional coefficients,the design parameters of the cutting coal test platform are determined,and the main transmission device,fixed device,propulsion device,sealing device and other main parts are completed After the assembly,a test platform for cutting coal was successfully constructed.By applying the same traction speed and cutting speed to coal samples in different mining areas,the relationship between the physical and chemical properties of coal and the characteristics of dust generation was studied.Laboratory test studies have shown that there are large differences in the dust concentration and crushing characteristics between different coal samples,which are closely related to the physical properties of the coal.The moisture in the coal has an inhibitory effect on cutting and crushing dust.The higher the moisture content of the coal,the lower the cumulative proportion of respirable dust and PM2.5;the higher the fixed carbon content in the coal.,The higher the dust production rate,the higher the cumulative proportion of respirable dust and PM2.5;the law between volatile content and dust production characteristics is not obvious;the higher the solidity coefficient,the easier it is to break.The corresponding dust generation rate is also lower.Finally,based on the discrete element theory and using the EDEM discrete element simulation software,a simulation model for cutting coal was constructed,and the method of controlling variables was used to study the characteristics of coal samples with different properties.Numerical simulation studies showed that:Under the same cutting parameters,there is a big difference between the loads when cutting different coal samples.According to the formula of cutting specific energy consumption,under the condition of the same cutting volume,the cutting specific energy consumption is affected by the cutting resistance.The greater the dust production,the greater the cutting resistance.The simulation shows that the order of the dust production of each coal sample is consistent with the experimental conclusion.Figs[46]table[13]references[76]...