61 / 2023-05-15 23:12:17

Research on the Mechanism and Inhibition Performance of Thickened Slurry for Preventing and Suppressing Spontaneous Combustion of Coal in Large Dip Mining Faces

Coal spontaneous combustion,Large dip angle mining face,Thickened slurry,Rheological properties,Resistance effect

Coal spontaneous combustion is one of the main natural disasters in China's coal mines. With the increasing depletion of coal resources in China, the coal mining in the central and eastern regions of China has gradually shifted to the deep and complex tectonics areas, and the mining proportion of steep seam is increasing. In response to the problems of unfavorable water accumulation in the goaf of steep dip mining face, easy accumulation of heat generated by air dried coal oxidation and spontaneous combustion, difficulty in implementing conventional grouting measures, high air leakage intensity, and inability of slurry to pile up high, etc. Using sodium alginate (SA), apigenin and loess as raw materials, a new type of thickened slurry material was prepared to prevent spontaneous combustion of coal in steep dip mining face. In order to explore the rheological properties of a new type of thickened slurry material, the rheological properties of the thickened slurry were studied using a rotary rheometer. During the experiment, Fourier transform infrared spectroscopy and scanning electron microscopy were used to study the evolution of functional groups and microcrystalline structure of coal samples before and after inhibition, thereby revealing the fire prevention and extinguishing mechanism of thickened slurry materials. Based on the experimental instrument of the coal spontaneous combustion indicator gas testing system, analyze the changes in the amount of coal spontaneous combustion gas generated before and after inhibition. The experimental results show that when the water to soil ratio is 8:1 and the mass fraction of suspended colloid is 0.3%, the thickened slurry has good suspension performance and good flowability, which is conducive to pumping. The thickened slurry prepared in the experiment is a non-Newtonian fluid with shear thinning characteristics. Its rheological properties conform to Herschel Bulkley model, and the correlation coefficient R² is greater than 0.99. Experimental observation shows that the surface of the coal sample treated with thickened slurry is relatively smooth and no large pores can be seen, indicating that the thickened slurry material has excellent permeability to pores and can seal the pore structure of the coal sample. In addition, thickened slurry materials can affect the changes in the content of various functional groups in coal, thereby affecting the low-temperature oxidation of coal. In the end, the experiment found that after treating the coal sample with thickened slurry material, the CO generation of the coal sample decreased at the same temperature, and the intersection temperature of the coal sample increased after treatment, indicating that the thickened slurry delayed the oxidation and heating process of the coal and had good resistance performance.