Basic knowledge of coal mines

Coal mines refer to places rich in coal resources, and usually also refer to factories that produce coal through underground mining or open-pit mining. What else do you know about coal mines? The following is the content of coal mine knowledge compiled by me. I hope you like it!

Introduction to coal mines

Coal mines are The reasonable space excavated by humans when excavating geological layers rich in coal usually includes roadways, shafts, mining faces, etc. Coal is the most important solid fuel and a type of flammable organic rock. It is formed by the luxuriant plants growing in a certain geological age, gradually accumulating into thick layers in a suitable geological environment, and being buried in the water bottom or sediment. It is formed through natural coalification over a long geological age. Among the various geological periods in the world, the Carboniferous, Permian, Jurassic and Tertiary strata produce the most coal and are important coal-forming eras. The carbon content of coal is generally 46 to 97%, it is brown to black, and has a dull to metallic luster. According to the degree of coalification, coal can be divided into four categories: peat, lignite, bituminous coal and anthracite.

Coal mining in China must be done in accordance with the law, and the licenses must be complete and valid. Implement the safety production policy of "safety first, prevention first, and comprehensive management".

History of Coal Mine Production

As early as the Neolithic Age, humans have records of using coal. The main use of coal mines is as fuel.

The earliest commercial coal mine in the United States was located in Virginia, where mining began in 1748.

Coal became the main source of energy in the Industrial Revolution in the 18th century, and steam trains and steamships began to become the main means of transportation in industrial countries. At the same time, the steelmaking industry also requires a large amount of coal mines. Gas is also needed for lighting, heating and cooking in cities. Britain invented many underground coal mining technologies at the end of the 18th century, and since then coal mining has entered the era of large-scale commercial mining. Machines for digging coal were invented around the 1880s; before that time, mining required manual digging with shovels or picks. By 1912, advances in steam excavator technology made open-pit mining possible.

Coal was the main source of industrial and transportation energy in Western countries from the 18th century to the 1950s. On the other hand, oil extraction technology has developed greatly in the early 20th century, and large-scale oil fields have been discovered in the United States, the Middle East and Indonesia. Oil has many advantages as a fuel over coal. Petroleum and its accessories began to become the main fuel after the 1950s, and steam engines were soon replaced by internal combustion engines. By the end of the 20th century, coal had been largely replaced by oil, natural gas, nuclear energy or renewable energy in households, industry and transportation.

Since 1890, coal mining has also become a source of political and social controversy. The use of child labor, exploitation of miners, and poor working conditions led to the formation of labor unions and the rise of socialist ideas. In addition, the extensive use of machines has also caused many miners to lose their jobs and caused many social problems. Restrictions on environmental standards and the mining of large-scale open-pit mines in the West caused the underground coal mining industry in the United States to decline sharply after the 1970s. At its peak in 1914, there were 180,000 anthracite miners in the United States, but by 1970 there were only 6,000 left. Asphalt jobs dropped from a peak of 705,000 in 1923 to 140,000 in 1970 and 70,000 in 2003. The number of active members of the Union of Mineworkers (UMW) also dropped from 160,000 in 1980 to 16,000 in 2005. The two oil crises in 1973 and 1979 caused governments around the world to start looking for alternative energy sources. While developing new energy sources such as nuclear energy, wind power, and solar energy, the importance of coal has once again received attention.

However, since the 1970s, environmental awareness has increased, and people have begun to pay attention to landscape damage, air pollution and other problems that may arise from burning coal. Compared with other fossil fuels, burning coal produces more greenhouse gases such as carbon dioxide, sulfur dioxide and nitrous oxide than oil or natural gas, and may be one of the main causes of global warming and acid rain.

Coal remains an important energy source today because of its economical price and abundant reserves, especially for power generation. Coal is the most important energy source in China. In 2005, about 80% of China's energy came from coal burning.

In 2007, China became a coal importer for the first time.

Types of coal mines

Open-pit mining

When the mineral seam is close to the surface, it is more economical to use open-pit mining. The soil above the mineral deposits is called topsoil. Explosives are planted in undeveloped areas of topsoil, and then the topsoil is removed using equipment such as dredges, backhoes, and trucks. This topsoil is then filled into previously mined pits. After the topsoil is removed, the ore layers will be exposed; the ore blocks are then drilled or blasted into pieces, and the ore is transported by truck to a coal preparation plant for further processing. When the ore is mined, repeat the same steps next door. Open-pit mining can yield a larger proportion of coal than underground mining because more seams are utilized. Open-pit coal mines can cover an area of ??several square kilometers. About 40% of the world's coal production uses open-pit mining.

Underground mining

Most of the mineral deposits are far from the surface, so open-pit mining cannot be used. Underground mining accounts for 60% of world coal production. In mines, the room-and-post method is often used to advance through the seam, with beams and columns used to support the pit. ***There are four main underground mining methods:

Longwall mining? A mining face approximately 300 meters or more in length. A sophisticated mining machine moves back and forth through a tunnel in the mine. Loose ore falls into the conveyor belt and is moved to the work area.

Continuous mining? A machine with a tungsten carbide drill bit is used to scrape coal from seams. Operate in a "room-and-pillar" system, working in a series of chambers of approximately 10 meters.

Blasting mining - a traditional method of mining. Explosives are used to break up seams and the ore is collected in mine carts. Or in a conveyor belt.

Short wall mining? Uses a continuous mining machine

Coal production

Coal mines are commercially mined in more than 50 countries. The world produces approximately 5.37 billion metric tons of hard coal per year (estimated in 2006). Most countries in the world have proven coal reserves. The coal mine reserves are estimated to be usable for another 147 years.

Coal mining methods

There are many types of coal mining methods. The coal mining methods used in the world's major coal-producing countries are generally classified as follows. There are two categories: wall type and pillar type. These two different types of coal mining methods are very different in terms of coal mining system and mining technology.

According to different mine geology and technical conditions. , different coal mining systems and coal mining techniques can be matched to form a variety of coal mining methods. For example, under different geological and technical conditions, longwall coal mining method, pillar coal mining method or other methods can be used. Coal mining method, and long wall and pillar coal mining methods are very different in terms of coal mining system and coal mining technology. It can be considered that the coal mining method is composed of two parts: coal mining technology and mining tunnel layout.

Wall coal mining

The wall coal mining method is characterized by a long coal wall, and the tunnels at both ends of the working face are used for air inlet and return air, coal transportation and material transportation. The mined coal is transported out of the working face parallel to the coal wall. In my country, the wall mining method is often used to mine coal seams.

Pillar mining

Characteristics of the pillar mining method. The coal wall is short and square-cylindrical, and a large number of working faces are mined at the same time. The mined coal is transported perpendicular to the direction of the working face.

Other mining methods

1. Trend. Longwall coal mining method, a coal mining method in which the long wall working face advances along the direction.

2. Inclined long wall coal mining method, a coal mining method in which the long wall working face advances along the slope.

3. Inclined layered coal mining method, a mining method in which thick coal seams are divided into layers along the inclined plane

4. Long-wall top caving coal mining method, after mining at a gentle slope of more than 6 meters. When the coal seam is gently sloping, the coal in the long wall working face at the bottom of the coal seam is mined first, and then the top coal is mined.

5. In the steeply sloping coal seam, the coal mining method is along the steep slope. The coal mining method is to arrange the coal mining face, use shield supports to separate the goaf area and the working space, and advance toward the slope.

6. Pseudo-inclined flexible shield bracket mining method.

In sharply sloping coal seams, the coal mining working face is arranged pseudo-inclined, and flexible shielding supports are used to separate the goaf and the working space. This is a coal mining method that advances along the strike.

7. Inverted bench coal mining method. In the stage or section of sharply sloping coal seams, a stepped working face in the lower part is arranged in advance and the coal mining method is advanced along the strike.

8. Positive bench mining method. In the stage or section of a sharply inclined coal seam, an upper step-shaped working face is arranged in a pseudo-inclined direction and advanced along the strike.

9. Horizontal layered coal mining method. A coal mining method that divides steeply sloping thick coal seams into layers along the horizontal plane.

10. Inclined layered coal mining method. A coal mining method that divides the sharply inclined thick coal seams into layers along a slope of 25 to 30 degrees to the horizontal plane.

11. Room-and-pillar coal mining method is a coal mining method that first mines coal rooms at certain distances along the tunnel until the boundary, and then retreats to mine the coal pillars between the coal rooms.

12. House-type coal mining method. A coal mining method in which coal rooms are mined at regular intervals along the tunnel and coal pillars are retained between the coal rooms to support the roof.