Our earth has a variety of natural resources, among which mineral resources are related to our daily food, clothing, shelter and transportation. And we can't help but ask, as the "mother" of mineral resources, the mine is left behind after being mined? In fact, the "mineless" mountain can also be turned into treasure!
Open-pit mine in Huolin Gol City, Inner Mongolia (stock copyright picture, reproduction may cause copyright disputes)
01 What is an abandoned mine?
A mine is an artificially constructed place where minerals are mined in a three-dimensional space. Due to the non-renewable nature of mineral resources, almost all mines have their own "lifespan". Once the recoverable resources are exhausted, the mine faces the fate of abandonment or closure, becoming an abandoned mine.
In general, the abandonment of mines is often abandoned due to the depletion of resources. However, in recent years, many mines have been closed due to environmental protection and ecological red lines, becoming a new form of mine abandonment, which is different from mines abandoned due to resource depletion, and in essence, this kind of mine is more like a "dormant mine" - because this kind of mine often has a certain amount of resources to be mined, and it can be converted into a production mine again after the level of production technology and environmental protection technology is improved in the future.
A mine is an artificially constructed place where minerals are mined in a three-dimensional space. (Stock copyright pictures, reprinting and using may cause copyright disputes)
Whatever the reason, once it becomes an abandoned mine, it means that the mine can no longer continue to provide human resources with the original mineral resources, that is, "dormant mines" or closed mines. However, some abandoned mines may be reborn or re-mined after they are abandoned.
02 Hazards of abandoned mines
With the advancement of mining and production, harmful gases will be released from the ore body or mountain, resulting in a variety of geological problems such as water inrush and rock burst, which require artificial ventilation, drainage and anchoring intervention to ensure the safety of mining operations.
When the mine is abandoned, the original mineral production behavior is terminated, the original ventilation, drainage and other activities are terminated or even the related system is dismantled, leaving only a hollowed-out cavity or roadway in the three-dimensional space, but because this cavity or roadway is often lower than the surrounding non-mining area, a large amount of water and gas will be generated in the goaf over time.
Due to the large amount of sulfur, phosphorus and other elements or acidic organic salts in the original ore-bearing horizon, part of the stagnant water is leached for a long time to form acidic mine water, which overflows the ground or pollutes groundwater after accumulation, resulting in water pollution.
Some abandoned mines, such as abandoned coal mines, produce a large amount of coal bed methane in the goaf, which accumulates and overflows from the cracks on the surface of the coal mine, causing methane leakage, polluting the atmosphere, and even exploding when encountering open flames.
Some shallow buried and deep underground coal mines will cause a large number of goaf collapse after abandonment, forming mine geological disasters such as ground fissures or surface subsidence, or forming underground coal fires.
After the open-pit mine is abandoned, due to the destruction of surface vegetation, the stratum is exposed to the surface for a long time, and suffers from weathering and denudation, resulting in geological disasters such as debris flows and landslides.
03 Abandoned mines are actually full of treasures
After the mine is abandoned, a variety of secondary resources are often formed:
Intangible and tangible resources
Intangible resources: refers to the mining culture contained in it, such as the history of mining, the spirit of mining and other intangible resources.
Physical resources: abandoned roadways, railroad tracks, buildings, squares, building land, etc., as well as the three-dimensional space above and below the mine.
It is divided according to the form of existence of matter
Solids: tailings, surrounding rock, residual minerals, etc.;
Liquid: mine water, water in underground goaf, water in ground subsidence area, etc.;
Gas: coalbed methane (such as methane, carbon dioxide, etc.);
Many Carboniferous-Permian coal mines in North China contain a large amount of under-coal bauxite resources, rich in lithium, gallium and other "three rare" mineral resources in the roof and bottom of coal mines, and a large amount of coalbed methane and mine water resources in the goaf.
03 Development and utilization of abandoned mines
For abandoned mines, the best restoration is often not to abandon them, but to carry out natural ecological restoration in the secondary development and utilization. For example:
Land leveling and reclamation in open-pit abandoned mines to create new farmland.
Areas with heavy rainfall can be built into artificial lakes or lakeside parks according to local conditions. For example, the Pan'an Lake National Wetland Park in the Jiawang mining area of Xuzhou in mainland China has become a national 4A-level tourist attraction.
A corner of Pan'an Lake National Wetland Park (Source: Xinhua News Agency)
After the coal mining subsidence area of the abandoned coal mine mined by underground engineering is slightly leveled, a photovoltaic power generation base can be built on it, such as the first batch of photovoltaic "leader" demonstration bases in Datong Yungang District, which is famous on the Internet.
Photovoltaic power generation project in Datong City (Source: Xinhua News Agency)
Abandoned mines adjacent to the edge of the city can also be converted into pit hotels or competition venues. For example, the Wangping Mining Area, located in Mentougou District, Beijing, will build a cultural tourism resort hotel with the theme of "Coal Industry Culture + Hotel Leisure". The Xinqiu open-pit mine in Fuxin, Liaoning Province, was built into an international mountain car international circuit city after its closure, and became a new world for racers to gallop.
Some of the relics with a long history and ancient mining history can be built into heritage museums. For example, the Tonglushan Ancient Copper Mine Site Museum in Daye, Hubei Province, can be traced back to 4,000 years ago at the earliest, and is the ancient mining and metallurgical site with the longest mining and smelting duration, the largest mining and smelting scale and the most complete preservation found in the mainland.
The new museum of the ancient copper mine site in Tonglu Mountain (source: Xinhua News Agency)
Well-sealed abandoned underground salt cavern mines can be used as underground reservoirs for oil, gas, and carbon dioxide storage. For example, in the Jintan area of Changzhou, Jiangsu Province, and the Rongbing area of Zhenjiang, by the end of 2023, four abandoned salt cavern gas storage reservoirs have been built, realizing the reuse of 1.2 million cubic meters of underground space.
It is also possible to use the roadways and goafs of abandoned mines to build energy storage power stations, such as:
Pumped storage power station: use the three-dimensional underground space with height difference formed by underground mining or open-pit mining to form two storage reservoirs with different height differences, and use the natural gravitational potential energy formed by the height difference between water bodies to generate electricity.
Compressed air energy storage: use the coal mine roadway or cavern space to convert electric energy into air potential energy through compressed air during the peak period of power generation, and release air into electric energy during the peak period of electricity consumption, so as to shave the peak and fill the valley and replenish the electric energy.