Study On Grain Size Distribution And Spont-Aneous Combustion Characteristics Of Gan-Gue On Slope Surface Of Gangue Hills In Dry Multi-wind Mining Area

As the growth of the coal resources in the global energy demand,the trend of the coal mining has steadily increased throughout the country,then there is a series of coal gangue,coal gangue in the domestic general is given priority to with emissions along the ditch and natural accumulation,the accumulation of long time will not only lead to internal oxidation of fuel coal gangue hills,serious can also lead to coal gangue hills in spontaneous combustion,especially in dry and windy areas,coal gangue hills is more prone to spontaneous combustion due to less rainfall and more wind in four seasons,which has an impact on environment.If the gangue hills in dry and windy mining area can be taken as the research object,the influence factors of gangue spontaneous combustion can be studied,and the characteristics of heat source distribution and temperature change in the gangue hills can be fully understood,so we can treat the gangue mountain pertinently and provide reference for the method of further disposal of gangue.On the basis of theoretical analysis,the coal gangue hills in a typical dry and windy mining area in Inner Mongolia is selected as the research,and the characteristics of spontaneous combustion such as particle size distribution and internal temperature distribution on the slope surface of coal gangue hills are studied.Firstly,fractal theory was used to study the grain size distribution characteristics of gangue hills.The concept of similarity simulation is introduced to measure connected porosity and permeability.On this basis,combined with relevant theories of heat transfer,the numerical simulation test of gangue hills was carried out,and the spontaneous combustion characteristics of gangue hills were further analyzed based on the field measured data to verify the reliability of simulation.The main research results are as follows:(1)There is a certain regularity between the grain size distribution and fractal dimension of gangue,and the fractal dimension reflects the grain size composition of gangue.The smaller the fractal dimension is,the more gangue with larger grain size is,and the larger the average grain size of gangue pile is.(2)The smaller the gangue particle size is,the smaller the connected porosity of porous media is,and the larger the gangue particle size is,the larger the connected porosity is.It can be seen from the experiment that with the increase of gangue hills height,the connected porosity of gangue hills is gradually smaller.There is a linear relationship between the permeability of gangue hills and the distribution parameters of gangue and the maximum particle size of gangue in the interval.(3)The temperature distribution in gangue hills is simulated by using different porosity and wind speed conditions.The simulation results show that in the same accumulation time,with the porosity gradually increasing,the maximum temperature that can be reached in gangue hills increases first and then decreases.With the increase of wind speed,the highest temperature in gangue hills moves from the windward surface of gangue hills to the middle of gangue hills and the leeward side.(4)The high temperature area of the gangue hills is mainly located 2.0～3.5m below the surface of the gangue hills.The whole gangue hills can be divided into three zones according to temperature and spontaneous combustion tendency,namely low temperature zone,medium temperature zone and high temperature zone.The starting point of spontaneous combustion of gangue hills is the highest internal temperature.The whole gangue hills internal combustion is not uniform,belonging to partial combustion.Through the above research,the relationship between the particle size distribution and the fractal dimension of coal gangue hills slope surface is understood,the influence factors of porosity and permeability are analyzed,and exploring the open pore rate and different wind speed influence on spontaneous combustion characteristics of coal gangue hills,clearing that we can change the particle size distribution of coal gangue hills,change the connected porosity,and then change the influence of interference wind speed on internal temperature field.It can provide theoretical basis and reference value for the treatment of coal gangue hills in the future.