The process of coal mining, processing and refining.

Coal mining is the hardest work and efforts are being made to improve working conditions. Due to the different burial depths of coal resources, mining methods are generally divided into mine mining (deep burial) and open-pit mining (shallow burial). More than two-thirds of underground coal production is mined by room-and-pillar method using continuous mining machinery. The continuous shearer with tungsten alloy bit cuts coal from the surface side by side, and then it is transported to the car waiting to pick up the car, transported to the conveyor belt and transferred to the ground. The shearer moves forward for a certain distance, stops moving, and then puts it into the support. This process is repeated until the coal seam is mined. No blasting is used. Another underground mining method is longwall mining, which accounts for about 20% of the output. This method uses a cutting machine that spans 400 to 600 feet of coal seam (longwall). This machine has a rotary cylinder tungsten drill to cut coal, and then the coal is sent to the conveying system, and then it is taken out of the mine. The roof is supported by large steel and connected to the machine. As the machine moves forward, the roof bracket will also move forward. This method can be used in nearly 80% coal mining. The remaining 1 1% underground output was made by the traditional explosion method used in mining, and the coal was removed after the explosion. Coal is an important energy source and an important raw material for metallurgical and chemical industries. Mainly used for combustion, coking, gasification, low-temperature dry distillation, hydro-liquefaction, etc. (1) combustion. Coal is an important energy source for human beings, and any coal can be used as industrial and civil fuel. ② Coking. When coal is heated in a dry distillation furnace isolated from the air, the organic matter in coal gradually decomposes with the increase of temperature, in which volatile substances escape into coke oven gas and coal tar in gaseous or vapor state, and the nonvolatile solid residue is coke. Coke oven gas is a kind of fuel and an important chemical raw material. Coal tar can be used to produce fertilizers, pesticides, synthetic fibers, synthetic rubber, paints, dyes, medicines, decoctions and so on. Coke is mainly used in blast furnace ironmaking and casting, and can also be used to make nitrogen fertilizer and calcium carbide. Calcium carbide is a synthetic chemical product such as plastic, synthetic fiber and synthetic rubber. ③ Gasification. Gasification refers to the conversion into gas that can be used as industrial or civil fuel and chemical synthesis raw materials. ④ Low temperature dry distillation. Low temperature tar and low temperature coke oven gas can be produced by dry distillation of coal or oil shale at about 550℃. Low temperature tar can be used to prepare advanced liquid fuel and as chemical raw materials. ⑤ Hydroliquefaction. When coal, catalyst and heavy oil are mixed together, the organic matter in coal is destroyed at high temperature and high pressure, and reacts with hydrogen to convert into low molecular liquid and gaseous products, and further processing can obtain liquid fuels such as gasoline and diesel oil. The raw coal for hydro-liquefaction is mainly lignite, long flame coal and gas coal.