Experimental study on microscopic properties and oxidation performance of weathered water-leached coal

In order to reveal the change law of microscopic pore structure and oxidation kinetic parameters of coal under natural air-drying conditions after water immersion, the water-soaked coal sample of the Jurassic Yan’an Formation 3^# coal seam of the Cuimu Mine in the Linyou District of Yonglong mining area is selected as the experimental research object in this paper.The change of the concentration of the characteristic gas in the high temperature stage and the low temperature oxidation stage of the coal sample, and explains the natural weathering process of the water-leached coal and the influencing factors of the residual coal oxidation.The research results show that the percentage of large pores in the total coal sample increased from 36.71% in the original coal sample to 46.78% in the coal sample after water immersion for 60 days, and the medium pores with inner diameters ranging from 10 to 1 000 nm accounted for the percentage of the total coal sample pores, the change trend is not obvious.The percentage of micro pores in the total pores of the coal sample decreased from 31.20% in the original coal sample to 23.18%, and the total pore area did not show a significant increase, but the average pore size, permeability, porosity of the coal sample significant changes have taken place; external moisture promotes the increase in the content of oxygen-containing functional groups such as carbonyl and carboxyl groups in the left coal, and the interior of the left coal further enhances the spontaneous combustion tendency of the coal, and the increase of oxygen-containing functional groups further makes the left coal.In the process of spontaneous combustion, more CO gas products are generated than the original coal samples; the average apparent activation energy of the low temperature stage and the high temperature stage in the primary and secondary oxidation heating and cooling processes of the original coal samples is 44.06, the long-term water immersion air-dried coal samples, and the average value of the apparent activation energy in the low temperature stage and the high temperature stage in the heating and cooling process of the primary and secondary oxidation is 33.71, and the average value of the apparent activation energy decreased by 23.49%.