Sudden emission and casualty accidents caused by abnormal enrichment of hydrogen sulfide (H2S) in coal mines are becoming frequent increasingly, causing major casualties and environmental pollution. Scholars in various countries have developed various measuring devices for hydrogen sulfide content in coal and rock formations and their calculation methods. The existing prevention and control technologies of H2S in coal mines were summarized in various countries. According to the distribution characteristics, occurrence modes, and emission forms of H2S in coal mines, the prevention and control technologies of H2S in coal-bearing strata, airflow in tunnel, and underground water body are mainly introduced. Analyzed the effects of different ventilation systems on prevention and control of H2S, which include conventional ventilation system, partial homotropal ventilation system, and full homotropal ventilation system. The methods used mainly include neutralization by injecting alkalizer through drilling in coal seams with high pressure, spraying alkalizer in tunnel, attenuation by increasing wind amount, changing the ventilation method, pumping, dredging, and blocking the water that contains H2S as well as comprehensive prevention and control method. The basic agents adopted mainly include sodium carbonate (the mass percentage concentration is about 0.5% ~ 3.0%) and sodium bicarbonate solution, and some basic solution is added by an additive, such as surfactant, Fenton reagent, sodium dodecyl benzene sulfonate, sodium hypochlorite, or chloramine-T. The treatment effect and the main problems of each prevention and control technology are analyzed, and a comprehensive method of prevention and control techniques of H2S in coal mines is proposed. According to current technological level as well as the cost, the effective prevention and control techniques of H2S should take the occurrence, distribution, and emission forms of H2S in coal mines as well as the content into consideration.

a b s t r a c tThe role of thermochemical sulfate reduction (TSR) is one of the main causes of high contents of hydrogen sulfide (H 2 S) in coal and rock formations. Sulfurous gas coal was selected from the Jurassic Xishanyao Formation in the Xishan coal mine of the Urumqi Anomaly Accumulation Area, using high-temperature and high-pressure reactors to simulate eight temperature-level experiments at 250°C-600°C. Four reaction systems of coal, coal + water, coal + water +sulfate, and coal + water + calcium sulfate and the evolution characteristics of gaseous products were analyzed. The TSR reaction has three stages of initial non-autocatalytic reaction, autocatalytic reaction, and late non-autocatalytic reaction. In the initial low temperature stage, physical desorption mainly occurs and TSR is weak. With the progress of the TSR reaction, hydrocarbon gases increase and non-hydrocarbon gases decrease. TSR can greatly promote the formation of hydrocarbon gases, especially methane gas, and methane is difficult to participate in TSR. TSR action occurs with the generation of heavy hydrocarbons. The TSR reaction leads to the drying of gaseous components, that is, the TSR reaction is more likely to occur in gaseous hydrocarbons with more carbon numbers. The change of CO 2 yield from down to rising can be better characterized as the characteristics of TSR. The yield of H 2 the change is wavy, which may be related to the supply and consumption of sulfur radicals and hydrogen in the coal and the formation of H 2 S. In the coal and coal + water reaction systems, H 2 S production is less; it is a low degree of response to the TSR reaction, mainly the hydrocarbon thermal cracking; the water in the process of the pyrolysis of coal into a gas cracking process plays an enormous role. The addition of calcium sulfate and magnesium sulfate promotes the TSR reaction and accelerates the cracking of heavy hydrocarbon gases. MgSO 4 initiates the TSR reaction more easily than CaSO 4 .

The regional structure of Xishan coal mine, located in the binding site of southern margin of Junggar basin and northern mountain Tianshan, belongs to the foothill fault-fold structural belt of southern margin of Junggar Basin. Most the coal seams which were formed by continental facies are in the range of medium-extra low sulfur and part of the coal seams belong to high sulfur coal. The hydrogen sulfide in coal seam concentrate anomaly and distribute very unevenly, with the maximum value of H2S up to 2.11%. The gas composition in coal bed mainly are N2 and CH4, components H2S, CO2, C2H6, C3H8 and another heavy hydrocarbon. The mirror reflectance of coal is generally between 0.5% to 0.7%. The abundant source rocks are the strong material basis for the formation of H2S. The pore structure of coalbed belongs to the fracture-pore type. The medium and better reservoir have a wide range of distribution. The proportion of roof microclastic rocks and floor microclastic rocks of coal seam is up to 75% and 87% respectively. These factors are conducive to the enrichment of H2S. The thick aquifer formed in the sag basement, under the control of hydrodynamic block gas, provides a huge space of occurrence and migration for groundwater and H2S. Along the runoff direction, the salinity, pH value and H2S content in regional groundwater gradually increase. The water is rich of sulfate ion, reflecting a closed well of regional deep confined water. In sufficient organic matter and reducing environment, the hydrogen sulfide will come into being in the role of BSR or TSR.