Production Laws of Mark Gases for Spontaneous Combustion of Water-soaked Coal in Northern Shendong Mining Areas

Temperature programming experiment of coal spontaneous combustion and oxidation were used to study the laws of spontaneous combustion mark gas of water-soaked coal. The generation rate of CO, CO₂, CH₄ and concentration of C₂H₄, C₂H₆ and oxygen consumption rate were studied between different rates of water content of water-soaked coal and raw coal samples. It is found that in the stage of low temperature oxidation, the existence of water in the water-soaked coal reduces the temperature point of rapid oxidation and promotes the spontaneous combustion of coal. The production rate of CO and CO₂ and the oxygen consumption rate of the water-soaked coal are higher than that of raw coal samples. In the fast oxidation stage, the evaporation of water in the coal water has an obstructive effect on the spontaneous combustion of coal. The rate of CO and CO₂ gas production and oxygen consumption of the coal are lower than that of raw coal samples. In the accelerated oxidation stage and the high speed oxidation stage, the moisture of the water-soaked coal is combined with the functional group of coal molecular to produce a hydrous complex, which improves the production rate of CO and CO₂ gas and the rate of oxygen consumption, and prevents the production of alkane and olefin and reduces the concentration of C₂H₄ and C₂H₆. In the oxidation process of coal spontaneous combustion, the presence of moisture in the water-soaked coal reduces the adsorption capacity of CH₄ in raw coal samples, and CH₄ production rate of water-soaked coal is lower than that of raw coal samples. The results show that the water content has an obvious influence on the laws of spontaneous combustion mark gas in the process of spontaneous combustion and oxidation of coal. The 12^# coal soaked in water in northern Shendong Mining Area is more easily oxidized and spontaneous combustion than its raw coal.