Effect Of Water Injection Of Ecological Wetting Agent On Coal Properties And Underground Microecological Environment

Coal seam water injection is an important means to reduce coal dust,prevent rock burst,gas outburst and spontaneous combustion in the process of coal seam mining.With the increase of coal seam mining depth,it gradually highlights the characteristics of high ground stress and low permeability.The traditional water injection means only adding anionic surfactants can not inject water in an endless stream of phenomena,and a variety of wetting agents are used for water injection.In the formation process of coal seam,microorganisms play a vital role.The disturbance of human activities in the process of coal mining and the influence of temperature,ventilation and water content make deep coal seam have a unique microbial community structure.As a very strong human disturbance factor,water injection in coal seam goes deep into the coal seam.It directly or indirectly affects the abundance and migration of all kinds of microorganisms in coal seam.In this paper,the occurrence law of local microbial community structure in deep coal seam is studied,the limitation reason of the restriction of water injection in deep coal seam by single anionic surfactants SDBS and SDS and the reaction mechanism of chelating agent ATMP with minerals in coal seam are analyzed.By means of surface tension test,contact Angle test,XRD test and infrared test,the mechanism of SDBS and ATMP is analyzed.It is revealed that the wetting effect of SDBS on coal is mainly manifested in that SDBS can enhance the wettability of paraffin chain in coal,and enhance its adsorption through hydrogen bond adsorption,charge adsorption and other forms.However,the minerals in coal produce Ca²⁺through hydrolysis and dissolution with SDBS,plus Ca²⁺in engineering water body,will precipitate with SDBS,can plug pores,is not conducive to the combination of surfactants and coal,affecting the wettability of coal.The chelating agent ATMP can effectively produce stable chelates with Ca²⁺,prevent the formation of precipitation,and greatly improve the wetting effect of SDBS on coal.The most suitable surfactant SDBS and chelating agent ATMP were selected for the compound test,and the results of ICP experiment,SEM experiment and fractal dimension were used as the response index.The optimal formulation of eco-friendly wetting agent was ATMP:SDBS=5:6.The wetting effect of SDBS and ATMP on coal body is maximized by the eco-friendly wetting agent,and the physical and mechanical properties of coal sample are obviously changed.The impact energy index decreases by 77.72%,the elastic energy index decreases by 92.79%,the uniaxial compressive strength decreases by 31.12%,and the dynamic failure time increases by78.58%.The ecological-friendly wetting agent can significantly reduce the bursting liability of coal.16s rRNA high-throughput sequencing technology was used to analyze the microbial community structure in the coal samples.It was found that,from the level of phyla,the dominant phyla of the bacterial community were Proteobacteria and actinomycetes,while the dominant phyla of the archaea community were Eukaryota and Eukaryota.The methanogenic bacteria included Methanobacteria,Methanoblobacter and Methanococcus.The correlation between microbial community structure and environmental factors in coal samples was analyzed by PDA analysis.It was found that Proteobacteria and actinobacteria were greatly affected by p H and SO42-,but Firmicutes and Bacteroides had little relationship with these environmental factors.From the perspective of the genus level of archaea,nitrosaminella and aerobic aminoxide Nitrococcus were significantly affected by NO3-,while Methanobacteria,Halobacteria and pyrogen,Methanobacteria and Methanobacteria were all affected by SO42-.When the coal samples were soaked with an eco-friendly wetting agent,methanococcus and Methanobacillus existed in the solution but were not detected in each coal sample.At this time,Methanococcus and Methanobacillus were inactivated and did not have the ability to produce methane due to the low pH of the solution.