Micro wetting characteristics of coal dust in Pingdingshan mining area and preliminary study on the development of dust suppressant

Coal mining is gradually extending to the deep,coal dust disasters occur frequently under the condition of deep mining,and the dust prevention and control is difficult.Coal dust removal mechanism and technology is still one of the difficulties and emphases in the basic research of scientific and efficient coal dust removal technology in deep mining.The mechanism of coal dust removal based on the microstructure characteristics of coal dust as well as the development of new coal dust suppressant was explored,utilizing the raw coal collected from the coal seam Ding,Wu,Ji and Geng of Pingdingshan Mining Area.Basic physical properties analysis (industrial analysis,XRD,BET,SEM and FT-IR),multi factor influence on wetting characteristics,wetting mechanism exploration at the molecular level and coal dust wetting agent modification discussion were conducted systemically by means of various physicochemical properties testing and molecular dynamics simulation.The results show that the wettability of the four typical coal samples increases in the order of the coal seam Ji,Geng,Ding and Wu.The significant differences of organic matter content,moisture content,ash content,inorganic mineral content,specific surface area and oxygen containing functional groups in coal dust show some significant impact on the wettability of coal dust.The results show that the greater the specific surface area,quartz content,hydroxyl and ether bond content are,the better the wettability,and the higher the fixed carbon content,and the worse the wettability.Using the results of infrared spectroscopy and molecular dynamics simulation of coal,and considering the characteristics of hydrophilic functional groups of coal dust in Pingdingshan mining area,the adsorption process of water molecules on coal surface modified by different numbers of hydroxyl and ether bonds was studied,and the strong correlation factors of wettability of coal dust were further revealed.The number of surface hydroxyl is positively related to the ability of adsorbing water molecules,while the number of ether bonds in coal dust has a maximum value for the ability of adsorbing water molecules.Based on the influence mechanism of micro characteristics of coal dust on its wettability,the wetting and dust removal characteristics of three kinds of non ionic surfactants on four groups of coal dust were investigated.According to the wetting mechanism of surfactant molecular structure on coal dust,the solution of introducing aromatic ring structure to realize the modification of new dust suppressor was proposed for the coal dust in Pingdingshan Mining Area.The research results can provide a reference for the scientific and efficient dust prevention of deep mines in similar mining areas in China.