Coal mining Introduction
As kind of combustible organic rock, coal is the most important solid fuel. According to the degree of coalification, coal mine is divided into four series that are peat, lignite, bituminous coal and anthracite. Coal mine is mainly used as motive-power-coal and coking coal according to its wide usage. For coal mining, there are mainly two kinds that are open-pit mining and underground mining. It’s important to choose suitable mining method according to the mine situation.
Open-pit mining refers to the exploitation of coal seam exposed after removing the topsoil and rock above the coal (overburden). The coal mining method is customarily called stripping method since the outcrops of coal have been mined and exhausted, it’s necessary to strip the topsoil and make the coal seam apparent. In Europe, open-pit mining is widely used to brown coal mine while in the United States, it’s same to most of anthracite and lignite. If you choose open-pit mining method, it’s most economic to quarry in the place where the terrain is flat; coal seam extends horizontally and it’s possible to make large-scale stripping. If the ore deposit is of topographic inequality or mountainous, it’s better to set up steps according to contour stripping method. One side is slope and the other side is almost vertical cliff. It’s worth noticing that the ground is damaged or completely destroyed if open-pit mining method is adopted. Some measures should be taken to regain the ground.
For those coal mines that are buried too deep and not suitable for open-pit mining, you should choose the underground mining method. There are three kinds of methods to get access to coal seam which are exactly vertical shaft, inclined shaft and footrill (adit).
Vertical shaft impact crusher is kind of vertical well that digs from ground to provide access to a coal seam or a few channels of coal seams. The vertical shaft digging from a level of coal seam down to another is called blind well. Under the shaft, the coal mined is poured into coal bunker located below the level of coal rake besides the vertical shaft.
Inclined shaft is kind of sloping tunnel that is devoted to the exploitation of non-horizontal coal seam or one to multiple coal seams from the ground. In the inclined shaft, belt conveyors which are specially used to transport coal and rail vehicles which can be used for transportation of personnel or materials are equipped.
Adit is kind of tunnel horizontally or nearly, digging where reveals the surface of horizontal or inclined coal seam. Usually with the coal digging, it’s allowed to use any conventional method to transport coal to the ground from working face continuously.