Development Of An Explosion-proof Dust Suppressant Based On The Effect Mechanisms Of Coal Dust Wettability And Explosion

In the process of coal mining,transportation and storage,secondary flying of deposited coal dust is a seriously problem,which has a had impact on the environment of mining area and the occupational health of workers.Under the shock wave,produced by the accidents of roof fall,impact ground pressure,coal and gas outburst in underground mines,the deposited coal dust can be rise rapidly and reachs the explosion concentration,which poses a serious threat to the life safety of underground workers.Therefore,in order to control the secondary flying and explosion of deposited coal dust in the underground,the purpose of this paper is to study the multi-parameter influence model of coal dust wettability and explosive,and to put forward the development method of explosion-proof dust suppression material,and to prepare an environmental-friendly explosion-proof dust suppressant.The physical and chemical characteristics of deposited coal dust(DCD)in underground mines were characterized and analyzed.18 DCD samples were obtained from 18 underground coal mines,locates in North China.Then,the physical and chemical properites of DCD were characterized,including the wettability,particle size distribution,pore parameters,explosion parameters,industrial composition,element content,vitrinite content and carbon functional group content.The results were compared with the characteristics of the coal dust prepared by ball mine in labs and reported in literature,and it was found that DCD dust has small particle size and well-developed pore structure.The average D10?D50?D90 of 18 DCD samples are 5.64,26.49,65.83 ?m,respectively,and its average breathable dust percentage(P10)is 21%,the highest P10 reachs 42%.In addition,the average BET surface area of 10 DCD samples is 8.24 m2/g,its average pore volume is 22.85 cm3/g,its average pore size is 11.82 nm.Smaller particle size distribution and well-developed pore structure make underground coal dust more difficult to settle.Based on the physicochemical parameters of DCD,the multi-parameter influence models of wettability and explosive of DCD are constructed using multi-factor analysis method,and the core factors affecting wettability and explosive of DCD are explored.It provides a theoretical basis for the development of explosion-proof dust suppressant.From the result of Pierce correlation coefficient analysis,we found that the wettability of DCD was affected by many physicochemical parameters.Then,combining factor analysis method and multiple linear regression method,the multi-parameter influence model of DCD wettability was constructed.From this model,the core factors affecting the wettability were coal dust pore parameters and chemical components.On the contrary,for the coal dust explosion,Pierce correlation coefficient analysis shows that there are few physicochemical parameters affecting coal dust explosive.Combining grey correlation degree analysis and multiple linear regression method,a multi-parameter model of coal dust explosive was constructed.The core factors affecting coal dust explosion intensity are fixed carbon content,C content and H content.The cumulative contribution value of the three is 79.40%.According to the core factors affecting coal dust wettability and explosive,the methods of improving coal dust wettability and reducing coal dust explosive are summarized,that is,increasing coal dust oxidation degree,increasing coal dust moisture content,increasing coal dust particle size and reducing coal dust surface roughness.According to the application conditions,the composite explosion-proof dust suppression material should have three functions,i.e.,wetting,bonding and water absorption and moisturizing,and its pH value should be neutral.Explosion-proof inhibition of molasses,a waste from sugar industry,on DCD was studied.The results showed that molasses solution had weak acidity,moderate wettability and moisture retention to coal dust,and remarkable adhesion and explosion inhibition to coal dust.Considering the deficiency of dust suppression by molasses solution,the compound compatibility with wetting agent,hygroscopic agent and pH neutralizer was explored by single factor variable method.The influence strength of each component on wind erosion resistance and explosion inhibition of coal dust was further explored using multi-factor orthogonal experiment method,and the optimum composition distribution ratio of molasses-based compound explosion-proof dust suppressant was determined.The industrial preparation technology of molasses-based explosion-proof dust suppressant was studied and designed,and its unit production cost and application cost were calculated.The unit production cost was 2626.45 yuan/ton,and the application cost of fully mechanized mining return air roadway was 0.16 yuan.Based on the environmental protection and non-toxicity of molasses-based compound dust suppressant components,the application technology of direct preparation of dust suppressant in well water tower is put forward.In order to improve the application effect of dust suppressant,an ultrasonic atomization device is developed based on underground air supply pipeline.The device has the characteristics of low water consumption and strong atomization ability.It can spray liquid evenly on the surface of roadway,which provides equipment guarantee for the efficient application of dust suppressant solution.Finally,the dust suppression performance of molasses-based compound dust suppressant was tested at industrial level,and the dust suppression agent had significant inhibitory effect on coal dust deposited in fully mechanized coal mining return air roadway.The dust suppression rate was above 60%within three days after spraying,the dust suppression rate began to decrease after the fourth day,and returned to the pre-spraying level on the seventh day,that is,the effective dust suppression period of the dust suppressant was 6-7 days;A 20 L spherical explosive device was used to test the explosion suppression characteristics of three kinds of coal dust,and the maximum explosion pressure of secondary bituminous coal,bituminous coal and anthracite coal dust was between 20%and 30%,and the explosion index was 57.45%,51.47%and 76.98%,respectively.This research provides a technical support for ensuring the occupational health and safety of underground workers and promoting the green and harmonious development of mines.The thesis contains 100 pictures,31 tables and 264 references.