Characteristics And Prediction Of Dust Pollution In Open-pit Coal Mines In Cold Regions

More than 80% of the open-pit coal mines in China are located in the cold northwest region,which belongs to the temperate continental climate,with cold and arid and serious dust pollution in winter.The scientific prevention and control of dust has become an urgent need for the sustainable development of open-pit coal mines,and it is also a practical problem that urgently needs to be solved in the process of accelerating the green transformation of open-pit mines.This thesis takes the dust pollution of the open-pit coal mine in the cold region as the research object,and comprehensively uses the methods of field measurement,theoretical analysis,laboratory test and numerical simulation to systematically study the dust pollution in open-pit coal mine in the cold region.The ventilation power of the near-horizontal open-pit coal mine in the cold region was systematically studied,the key factors affecting the dust concentration in the stope were analyzed,the pollution variation characteristics of the stope dust concentration and the law of dust diffusion were revealed,and the high-precision prediction method for dust pollution concentration and classification were proposed.The main research work is as follows:(1)The relative mining depths of several open-pit coal mines were analyzed,and it was concluded that the ventilation effect of the open-pit coal mines was better;the wind flow patterns of the stopes with different wind directions were studied,and it was determined that the circulation of the open-pit coal mines was mainly distributed in the side of the leeward slope;a stope model of a near-horizontal open-pit coal mine was established,and the distribution characteristics of total solar radiation,direct solar radiation,solar scattered radiation and direct solar radiation in different seasons were simulated by Arc GIS software.(2)The dust concentration and meteorological monitoring platform of the openpit coal mine was built.Through the monitoring data of three time periods,the production intensity data of the same period and the ECMWF high-altitude meteorological data,the statistical analysis of the data,the Kriging space interpolation and the gray correlation analysis were used to analyze the data.The influence relationship of multiple meteorological factors and production intensity on dust concentration at different times was studied,and a method for coordination of mining and discharge combined with meteorological conditions was proposed.(3)The change characteristics of the dust concentration in the mining area under different time periods were clarified,and the main pollutants in the stope were determined;laboratory experiments such as electron microscope scanning(SEM)and XRD were carried out to analyze the basic physical and chemical characteristics and microscopic morphology characteristics and potential sources of the dust;using FLUENT numerical simulation to determine the escape time and law of dust under different wind flows;combined with GDAS meteorological data,the 24-h forward trajectory of the air mass in the mining area was analyzed by HYSPLIT numerical simulation,and the potential for dust diffusion and pollution characteristics to the surrounding area was determined.(4)Based on the field measured data,combined with particle swarm optimization algorithm(PSO)and random forest algorithm(RF),the RF＿PSO hybrid model suitable for the prediction of dust concentration in opencast coal mines was proposed,and the significance of various factors affecting the current dust concentration was determined.By combining the group optimization algorithm(PSO)and the gradient lifting machine algorithm(GBM),a GBM＿PSO hybrid model is proposed for dust concentration prediction and dust concentration pollution classification in open-pit coal mines at long time intervals.This thesis analyzed the driving force of dust diffusion,factors affecting dust concentration,dust pollution characteristics and diffusion law in near-horizontal openpit coal mines in cold regions,and proposed a dust concentration prediction method.The research results provide theoretical basis and technical support for the comprehensive prevention and control of open-pit coal mine dust,and further promote the green mining of open-pit coal mines.The thesis has 68 figures,25 tables,and 139 references.