China's mine ecological environment

1. Mining waste gas
Because of gas, dust and waste caused by air pollution and emissions of acid rain, sulfur and coal chemicals most serious. For example, the industrial waste gas emissions in the coal mining industry reached 395.43 billion cubic meters per year, of which the pollutant emissions were 731,300 tons per year, mostly soot, sulfur dioxide, nitrogen oxides and carbon monoxide. The atmospheric environment in the mining area was polluted to varying degrees. Usually, 1 ton of sulfur is required to emit 10,000 cubic meters of harmful gas, which contains 1.8 tons of sulfur dioxide and hydrogen sulfide, and produces a large amount of waste water and harmful substances such as mercury , arsenic and cadmium . Soil sulfur production in provinces such as Hubei, Yunnan, Guizhou, and Sichuan is a production mode that destroys the ecological environment and constitutes a serious social hazard. In addition, the pollution of the waste and tailings to the atmosphere is also quite serious. For example, in some living and welfare areas of some non-ferrous metal mines in Henan, the dust content in the air exceeds the standard by ten times to several tens of times.
2. Mining wastewater The various wastewaters produced by China's mining activities mainly include pit water, mineral processing, smelting wastewater and tailings pond water. Wherein the coal, various metals, non-metallic mineral of the acidic waste water mainly, and more with a large amount of toxic heavy metals and harmful elements (such as copper, lead, zinc, arsenic, cadmium, hexavalent chromium, mercury, cyanide) and COD , BOD5, suspended solids, etc.; petroleum , petrochemical industry wastewater still contains volatile phenols, petroleum, benzene, polycyclic aromatic hydrocarbons and other substances. Many wastewaters are discharged without any standard treatment, and even discharged into the surface water body to contaminate the soil or surface water bodies. In addition, the groundwater is polluted due to the infiltration of discharged wastewater. [next]
(3) Mining waste residue Mine waste residue includes coal gangue, waste rock, tailings and so on. The cumulative stockpiles and floor space of various mining wastes (1995-1997) are shown in Table 2.

In 1997, the accumulated storage capacity of China's waste slag reached 6.472 billion tons, covering an area of ​​56.5 million square meters. The waste residue of mining and related industries was 5.851 billion tons, covering an area of ​​291.6 million square meters. Compared with 1995, compared with 1995. There has been a clear downward trend, but the proportion has increased, which should be taken seriously.
4. Soil erosion and land desertification Mining activities, especially open-pit mining, have destroyed vegetation and hillside soils in large quantities, and the loose materials such as waste rock and waste residue are very likely to cause soil erosion in the mine area. For example, in the Shenfu Dongsheng mining area on the Ordos Plateau, due to the influence of climate and human factors, the ecological environment of the area has been very fragile. The area of ​​desertification and desertification has exceeded 41,700 square kilometers, accounting for more than 86% of the total area. . According to a survey of 1,173 large and medium-sized mines across the country, the area damaged by soil erosion and land desertification is 1706.7 hectares and 743.5 hectares, and the cost of governance investment has reached 23.933 million yuan.
5. Karst collapse and goaf collapse The karst collapse is caused by the drainage of groundwater by karst water-filled deposits. Collapse not only occurs in coal mines but also in non-ferrous metals, ferrous metals, chemical and nuclear industries. From the geographical distribution, it is almost all over the southern provinces, especially in the provinces of Hunan, Guangdong, Hubei, Guizhou and Guizhou.
The destruction of land resources by the collapse of goafs plays an important role in mining, mainly caused by underground mining. In China's mining, mainly underground mining, according to 1173 state-owned large and medium-sized mines survey, underground mining accounted for 68.89%, subsidence area covers an area of ​​84201.4 hectares, accounting for 39.57% of mine development and destruction of land area. In addition, the underground cavity formed by the rock salt mining by water-soluble method can cause the ground to sink. Some salt mines have occurred, such as Hunan Xiangyu Salt Mine, Qiaoshi Salt Mine in Wuyuan County of Yunnan Province and Hubei Yingcheng Salt Mine Water Mining Base.
6. Invasion of land and mine development and occupation and destruction of a large number of land, where occupied land refers to the production, living facilities and development and destruction of the affected land; the damaged land refers to open pit, dumping sites, tailings, subsidence areas and other mines The area of ​​land destroyed by geological disasters.
According to the National Bureau of Statistics: During the period from 1957 to 1990, the country's land for construction, land abandonment, waste and disaster-damaged land reached 427,300 hectares, and the mine occupied 49.1%. China's mining industry destroys about 1.4-20,000 square kilometers of land and increases at a rate of 200 square kilometers per year. By 2000, it will reach 340 square kilometers per year. The cause of mine land occupation is caused by open pits and various types of slag and industrial waste.
According to statistics, a large mine covers an average of 180,000 to 200,000 square meters, and small mines also reach tens of thousands of square meters. By 1995, 1173 state-owned large and medium-sized mining enterprises occupied 72,9971.6 hectares of land, of which only open-pit mining, dumping, tailings and subsidence areas accounted for 21,2817.4 hectares, accounting for 29.15% of the mine land area. Other industrial land and administrative living land are 5,171.54 hectares, accounting for 70.85%. [next]
According to projections, by 1994, the area occupied by the national mine development was 986,000 hectares; accounting for 1.04% of the country's cultivated land area, which inevitably aggravated the situation of cultivated land in China. It is estimated that about 1.059 million hectares of forest land is occupied by the national mines. The forest area of ​​China is 134 million hectares, and the forest coverage rate is only 13.92%. For this reason, the situation of forest land occupied by mine development cannot be ignored. It is estimated that the national mine development covers an area of ​​about 263,000 hectares, while the grassland in China has been degraded, and the degradation rate has increased from 16% in the 1970s to 37%, with an average increase of 670,000 hectares per year. The problem of grassland degradation must not be ignored.

The water environment is mutated or even deteriorated due to the discharge of the drainage and waste water. Such as the destruction of surface water, groundwater balance system, resulting in a large area of ​​the drying funnel, dry spring water, gradual depletion of water resources, river water cutoff, surface water infiltration or subsidence into the ground, affecting the ecological environment of the mining area. Some mines in the coastal areas are constantly developing due to the drying funnel. When the boundary reaches the sea surface, it is easy to cause seawater intrusion. Surface water bodies near mines are often used as discharge places for wastewater and waste slag, and thus suffer from pollution. The pollution of groundwater is generally limited to the vicinity of the mine, which is caused by the leaching of the waste water and waste slag, the tailings pile, or the underwater surface of the contaminated surface.
For example, the Jinzhou asbestos mine at the southern end of the Liaodong Peninsula has been mined for nearly 30 years, and has reached the elevation of -400m. The long-term drainage and drainage caused seawater intrusion. As the mining depth increases, the seawater mixing rate increases.
11. Collapse, landslide, debris flow Mining activities and dumping debris are affected by terrain, climatic conditions and human factors, resulting in collapse, landslides, mudslides, etc. For example, the waste discharged from mines often accumulates in hillsides or valleys. These loose materials are prone to mudslides caused by heavy rain. One of China's largest gold producing areas, the Xiluogou Gold Mine in Qinling, Henan Province, was squandered and tens of thousands of cubic meters of slag were piled up at the bottom of the ditch, resulting in serious obstruction of the river. In mid-July 1994, the mudslides formed by heavy rains drained along the ditch, causing serious damage to roads and production and living facilities, and 51 people were killed and suffered heavy losses.

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