Study On Wind Erosion Of Typical Dust Sources In Wuhai Mining Area

The mining area of Wuhai city of Inner Mongolia is seriously affected by wind erosion.The study of wind erosion and its influencing factors of typical dust sources in this area plays an important role in dust pollution and sandstorm weather forecast.In this study,five typical dust source materials such as bare sand,loamy sand,fly ash,coking coal and coal gangue were taken as the objects in Wuhai mining area and surrounding areas.The threshold wind velocity,wind erosion rate and dust quantity of each dust source material were measured by wind tunnel test.The bulk density,particle size distribution and moisture content of dust source materials were measured by physical property experiments,and the influence of physical properties of dust source materials on wind erosion process was analyzed.The influence of relative humidity,temperature,wind speed and moisture content on wind erosion dust volume was analyzed by field measurement of 5 typical dust sources.The influence of meteorological factors on dust concentration in spring and summer was analyzed through long-term observation data of two monitoring stations in mining area and sand area.The results show that:(1)The threshold wind velocity of dust source material was bare sand > coking coal > coal gangue > fly ash.The wind erosion rate of bare sand increased linearly with the wind speed.The wind erosion rate of loam sand,fly ash and coking coal increased,and the growth trend of gangue was close to the exponential function wind the wind speed.The amount of dust emission in bare sand was related to the wind speed in a power function.The amount of dust emission in loam sand was in a linear relationship.While the amount of dust emission in fly ash increased with the wind speed in pairs.The amount of dust emission in coking coal and gangue was in a power function with the wind speed.(2)The bulk density of fly ash was obviously lower than that of other dust sources,which was the easiest to start.Particles with similar bulk density and refractory particles with high distribution frequency,small median particle size and uniform particle size distribution had greater resistance to wind erosion.There was a positive power function relationship between the threshold wind velocity and moisture content of bare sand.And the inflection point of wind erosion rate and dust emission with moisture content was 1%.The moisture content inflection point of loamy sandy soil was 2%.The moisture content inflection point of ash was 10%.There was a quadratic function between the threshold wind velocity and moisture content of coking coal.And the inflection points of wind erosion rate and dust emission of coking coal with moisture content were 4% and 2% respectively.There was a positive power function relationship between the threshold wind velocity and water content of gangue.And the inflection points of wind erosion rate and dust emission of gangue with its water content were 2% and 2% respectively.The higher the content of extremely fine sand particles of dust source material,the better the inhibition effect of wind erosion after consolidation.Bare sand and fly ash surface consolidation were easy to be broken.The surface consolidation of loam sand soil can resist wind erosion with a small wind speed,while the surface consolidation of coking coal and coal gangue can resist wind erosion with a large wind speed.The dust emission of field dust source increased with the increase of temperature,relative humidity and moisture content of typical dust source materials.The instantaneous increase of wind speed would cause dust from dust sources.(3)The increase of relative humidity in spring was not conducive to particle dispersion,while in the mining area and sand area in summer,the dust concentration started to decrease with the increase of relative humidity when the relative humidity was more than 60% and 40% respectively.There was a positive correlation between dust concentration and temperature in the mining area,but there was no significant correlation between dust concentration and temperature in the sand area.The dust concentration in mining area and sand area decreased with the increase of average wind speed at 2m.The primary influencing factors of dust concentration in mining area were temperature and wind speed in sand area.