Study on wetting characteristics of coal dust in soft coal based on principal component analysis

Mine coal seam dust production is closely related to the hardness of coal body，and the deep gas-bearing coal body often presents the characteristics of soft coal seams.In order to study the influencing factors of the wettability of the soft coal seams and to control the dust generation of soft coal bodies，the paper takes the contact angle，an important index to measure the wettability of coal samples and evaluate the dust disasters as the main line，seven coal samples with different degrees of softness were selected from 7 prominent mines in the Huaibei coalfield for coal-water contact angle measurement.Through industrial analysis，basic parametersof coal and gas，pore structure measurement and infrared spectrum quantitative analysis experiment，the wetting characteristics and main control factors of coal dust in soft coal were systematically discussed by principal component analysis.The results show that the wettability of soft coal body mainly depends on the content of ash，moisture，pore volume，specific surface area，firmness coefficient and hydroxyl content of coal，and the degree of influence decreases in order； Among them，ash content，moisture content，pore volume，specific surface area and hydroxyl content are negatively related to the contact angle，which is the hydrophilic factor of coal，and the firmness coefficient is positively related to the contact angle，which is the hydrophobic factor of coal.The lower the strength of coal body，the softer the coal body，and the smaller the coal water contact angle，the better the surface wettability of coal； The results of the principal component multiple regression analysis method show that the correlation between ash and coal-water contact angle is the highest and is the main controlling factor of coal surface wettability；the occurrence of gas affects the strength of coal body in the process of coal storage，and the adsorption and release of gas promote the cracking of primary cracks and the formation of new cracks，leading to the changes of physical and chemical properties of coal body，which indirectly affects the wettability of coal.