Coal mining technology

Coal mining has always been the hardest work, and people are trying to improve their working conditions. Due to the different burial depths of coal resources, mine mining (deep burial) and open-pit mining (shallow burial) are generally adopted accordingly. The proportion of open-pit mining resources to total resources is an important index to measure the advantages and disadvantages of mining conditions. China's open-pit mining reserves only account for 7.5%, the United States accounts for 32%, and Australia accounts for 35%. The quality of mine mining conditions is inversely proportional to the amount of gas in coal mines. The proportion of coal mine gas in China is high, and high gas and gas outburst mines account for more than 40%. Coal mining in China is mainly mine mining, such as Shanxi, Shandong, Xuzhou, Northeast China, etc., and there are also open-pit mining. For example, Huolinhe Coal Mine in Inner Mongolia is the largest open-pit mining area in China.

open pit

Remove the topsoil and rocks (overburden) above the coal seam and mine the exposed coal seam. This coal mining method is customarily called stripping mining, because the exposed coal has been mined out, and it is necessary to strip the topsoil to expose the coal seam. This method is most suitable for places where the coal seam is not deeply buried. Many modern open-pit mines use enough equipment to peel off the overburden with a thickness of more than 60 meters. In Europe,

Open-pit mining is widely used in brown coal mines, and most anthracite and lignite in the United States also use open-pit mining. Open-pit mining is the most economical mining area with flat terrain, horizontal extension of coal seam and large-scale stripping. When the topography of the deposit is undulating or mountainous, the method of stripping along the contour line is used to establish steps, one side is a hillside and the other side is an almost vertical cliff. If the ground is damaged or completely destroyed by open-pit mining, measures shall be taken to restore the ground. The laws of many states and federal governments in the United States have stipulated measures to restore land, and now many mining enterprises voluntarily implement these regulations.

Mine exploitation

For the coal seam with deep buried depth which is not suitable for open pit mining, three methods can be used to enter the coal seam, namely, vertical shaft, inclined shaft and adit.

Vertical shaft is a vertical well dug from the ground to provide access to a certain coal seam or several coal seams. A shaft dug from one coal seam to another is called a blind well. In the underground, the mined coal is poured into the bunker below the coal seam level next to the shaft, and then loaded into the shaft skip to be lifted from the underground.

Inclined shaft is a kind of inclined roadway used to mine non-horizontal coal seams or reach a certain coal seam or multiple coal seams from the ground. Inclined shaft is equipped with belt conveyor to transport coal, and personnel and materials are transported by rail car.

An adit is a horizontal or nearly horizontal roadway, which is excavated in a horizontal or inclined coal seam to reveal its source, often with the excavation of the coal seam. It allows any conventional method to continuously transport coal from the working face to the ground.