China's mine ecological environment and protection status

In the 50 years since the founding of the People's Republic By the end of 1997, there were 10,838 state-owned mines, 154,643 township collective mines, and 96,376 individual mining sites. The output value of independent accounting was 469.131 billion yuan, accounting for 6.86% of the total industrial output value. The total scale of mineral development ranked third in the world. Has become one of the world's largest mining countries. With the development of the mining industry, more than 300 mining cities have been newly built. However, the development of mineral resources, especially unreasonable development and utilization, has caused pollution to the mine and its surrounding environment and induced various geological disasters and destroyed the ecological environment. Increasingly prominent environmental problems not only threaten the lives of people, but also seriously restrict the development of the national economy. In particular, the township collective mines, which account for 59.06% of the total number of mines, have a large gap in environmental protection work. What is more serious is that the environmental protection work of individual mining sites accounting for 36.80% of the total is almost blank.
(I) Status of mine ecological environment China's mining activities mainly refer to three parts: ore mining, mineral processing and smelting. There are many types of ecological problems and damages caused by mining activities (Table 1). For example, direct damage to the land by mining activities, such as open pit mining directly destroys the surface soil and vegetation; waste in the mining process (such as tailings, vermiculite, etc.) requires a large area of ​​landfill, resulting in excessive land occupation and destruction of ecosystems existing storage yard; ore, slag-containing acidic, basic, toxic, radioactive or heavy metal solid waste components by surface water runoff, atmospheric particulates, contamination of the surrounding land, water and Atmospheric, its impact will far exceed the area and space of the waste dump. The pollution impact will take a lot of manpower, material resources and financial resources to recover after a long time, and it is difficult to restore to the original level.

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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 generated by mining activities in China mainly include pit water, beneficiation, 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.
3. Mining waste residue Mine slag 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, a large number of destruction of vegetation and hillside soil, the generation of waste rock, waste slag and other loose materials can easily promote soil erosion in the mining 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.

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7. Soil pollution Due to the discharge of three wastes , the soil around the mining area is polluted to varying degrees.
8. Earthquakes induced by mining and mining have appeared in many mines in China and have become one of the major environmental problems in mines.
9. Tailings Reservoir Breaking Dam According to statistics, there are about 700 tailings ponds in the country, and tailings reservoir dam breaks occurred in Jiangxi, Yunnan, Anhui, Hubei and other provinces.
10. Destroy the water balance system and cause water pollution . The water environment is mutated or even deteriorated due to the discharge of the drained water 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, landslides, 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.
(II) Prevention and protection of mine environmental problems The prevention and control of mine environmental problems mainly include: “three wastes” (waste water, waste gas, waste residue) prevention, mine land reclamation and ground subsidence (collapse) in goaf, mudslide, karst collapse Such as the prevention and control of disasters.
1. Exhaust gas treatment is mainly for the treatment of soot in kiln, material recovery and pollution in various production process waste gases. According to the statistics in 1985, the governance of the mining industry is shown in Table 5. Among them, the mining and ferrous metal mining industry has the highest processing rate, higher than the average of 40 industries (44.06%), and the lowest in the coal mining industry, ranking third in the 40 industries. The processing rate of the entire mining industry was 17.24%, which was lower than the average processing rate of 40 industries across the country. [next]

In recent years, Yunnan and Guizhou provinces have strengthened their environmental management of sulfur smelting by the local law, resolutely banned soil furnaces, and promoted new technologies for sulfur smelting. For example, Zhenxiong County of Yunnan Province has basically completed the technical transformation of sulfur smelting in the soil method, so that the recovery rate of sulfur is increased from 80% to 60%. The atmospheric concentration of SO ₂ around the sulfur-smelting plant area has reached the national average of GB3095-82. Grade standard (<0.25mg/m ³ ), green plants grow normally at the sulfur plant.
With the development of industry, exhaust emissions have shown an increasing trend (from 1993 to 1995, the growth rate was 10.36~15.04%), but since 1996, the growth has slowed down and the growth rate has shown a downward trend. This shows that with the implementation of the national policy of environmental protection, the efforts to control the “three wastes” have increased, and waste gas treatment has achieved certain results.
2, wastewater treatment
The types of wastewater discharged from mines in China mainly include acid wastewater, wastewater containing suspended solids, salty wastewater and ore dressing wastewater. In order to prevent pollution to the environment, it is mainly to reform the process, update equipment, reduce the discharge of waste water and pollutants, and improve the reuse rate of water; to treat waste and treat wastewater as a comprehensive utilization of resources.
The processing and utilization capacity of mine water in coal mining and selection industry has increased rapidly. In 1990, the compliance rate of external discharge was 90.56%, and the utilization amount was 212 million tons. The coal washing water discharge and the loss of coal slime were reduced, and the coal washing plant that achieved the closed cycle of coal washing water was 100 in 1990. [next]
In the past ten years, the non-ferrous metal industrial wastewater treatment technology has developed greatly, and wastewater treatment has evolved from single treatment to comprehensive planning and comprehensive management. The reuse rate of industrial water is catching up year by year. In 1973, it was only 12%. In 1987, it reached 58%. The recovery of valuable metals from wastewater has achieved initial success. At present, the first problem is that the capacity of the wastewater treatment plant is insufficient. According to statistics, about 30% of the wastewater is directly discharged without treatment; the second is that the development level of wastewater treatment technology is not high; the third is the management of water conservation and wastewater treatment. The system is still not perfect.
3, the treatment of waste residue treatment of mine waste is mainly comprehensive utilization, that is, the reduction of waste residue into the resource and energy. This is an effective measure to protect the environment, protect primary raw materials, and promote production savings.
According to statistics in 1996, state-owned key coal mines used coal gangue to 34.7 million tons, accounting for 48.5% of the current year's emissions, including 8 million tons for power generation, 8 million tons of building materials, 3.6 million tons of building materials, 3.6 million tons of road materials, and 990 filling materials. Ten thousand tons.
From 1991 to 1997, with the development of industry, the discharge of solid waste increased, but its comprehensive utilization rate also increased (from 37.92% in 1991 to 45.64% in 1997); the total storage since 1996 Decline, the area has decreased since 1996.
In general, mining waste accounts for half of the country's total solid waste, but the disposal rate is the lowest, which has a great impact on the mine environment. From the perspective of various types of mining, the utilization rate of waste slag in coal and building materials non-metal mining and selection industry is higher, while the disposal rate of slag in ferrous metal mining and selection industry is higher.

4. Land reclamation and waste slag site Land reclamation and land reclamation is the best way to control the ground subsidence, dumping site, tailings pile and open pit after the pit. It not only improves the mine environment. It also restores a large amount of land, so reclamation has far-reaching social, environmental and economic benefits. [next]
Since the 1960s, some mines in China have been carrying out reclamation work in succession. In the past ten years, the work of reclamation has gradually been valued by various mines and achieved remarkable results. However, in general, China's current land reclamation rate is still low, but it is only partially or sporadically restored. The reclamation rate is only 1%, of which the metallurgical mine is higher, reaching 10%, which shows the arduousness of its reclamation.
5, the prevention and control of debris flow Mine debris flow usually occurs in the early stage of dumping, with the increase in the amount of waste discharged and the increase in strength, the slope stability of the dumping site is often improved and strengthened, the mine debris flow will gradually weaken. The key to prevention and control of mine debris flow is prevention. The precautionary measures currently adopted in China mainly include the rational selection of the stripping site for the disposal of the site, the careful use of the “high step” method of disposal; the removal of the adverse effects of surface water on the stripping of waste; the planned arrangement of the rock pile Set; For the treatment of debris flow, biological measures (such as planting trees and planting grass) can be taken, but the time is long and the effect is slow. At present, in addition to strengthening the management of dumping sites and tailings ponds, most of the engineering control measures are adopted, mainly including barriers, drainage and spanning measures.
6. Prevention and control of karst collapse The prevention and control of karst collapse in China began in the 1960s. At present, there is a set of relatively stereotyped and mature methods. The key to prevention and control is to make scientific research on the collapse under the premise of mastering the mining area and regional subsidence laws. Evaluation and prediction, that is, adopting methods based on early prediction and prevention, supplemented by governance, and combined with prevention and control.
(1) Prevention of pre-collapse prevention The following main measures are taken: rationally according to the overall layout of mine construction; river diversion and drainage, avoiding subsidence areas; construction of extra-thick flood control dikes; control of groundwater level decline rate and prevention of sudden water inrush to reduce the occurrence of subsidence Construction of anti-seepage curtains to avoid or reduce the decline of groundwater level in the predicted subsidence area, to prevent the occurrence of ground collapse; establish a ground collapse monitoring network.
(2) The main control measures after subsidence are as follows: backfilling of collapsed caves; partial diversion of rivers and seepage prevention of river channels; comprehensive treatment.
7. The prevention and control of mine water balance damage is to prevent and prevent the water level damage caused by the drainage of groundwater, to protect groundwater resources, and to eliminate or reduce the environmental problems caused by groundwater collapse caused by drainage of groundwater, from 70 Since the beginning of the year, some mines have successively adopted anti-seepage curtains and anti-seepage walls to intercept the supply of groundwater in the surrounding area and achieved remarkable environmental and economic benefits. Such as Wang Zi stroke black iron ore using Impervious Curtain, the Danube river in Oita supply is being stopped, the effect of plugging up 61%.
(III) Main organizational measures and economic means of mine ecological environmental protection 1. Organizational measures
Mainly to establish a management agency and monitoring system for environmental protection. At present, the setting of mine environmental protection agencies in China is determined according to the degree of environmental pollution and the size of the enterprise in the construction and production process of the mine. In general, large-scale mines are set up in environmental protection departments, and small or medium-sized mines are established in sections or groups. Environmental protection personnel in mining enterprises mainly include: mine environmental protection scientific research personnel, environmental monitoring personnel, sewage treatment personnel, dust-proof personnel of mining enterprises, protection equipment maintenance personnel, mining area greening personnel, reclaiming field personnel. The mine safety organization related to environmental protection is relatively complete and has been set up for a long time. [next]
2. Economic means The investment of environmental protection of mining enterprises is part of the total investment in mine infrastructure. According to the current production situation of mining enterprises, the investment in environmental protection projects mainly includes the following aspects: three waste treatment facilities, dust removal facilities, sewage treatment facilities, noise prevention facilities, greening, radioactive protection, environmental monitoring facilities, and reclamation. The sources of investment generally include the following aspects: engineering infrastructure investment for new construction and expansion and expansion projects; self-raised funds for competent departments and enterprises; and sewage rebate fees, that is, environmental protection subsidy funds. The amount of investment in environmental protection projects depends on the conditions and requirements of mine construction. The sources of funding for environmental protection and governance are also directly related to the management and economic benefits of the enterprise.
3. The policy measures for the source of environmental protection funds are to protect the environment and control pollution. The State Council and relevant departments have formulated the Interim Measures for the Paid Use of Special Funds for Pollution Source Control and the “ Three Wastes” for the Management of Industrial and Mining Enterprises. Administrative regulations and departmental rules such as the "Forcing of Knowing" and "Notice on the Regulations on Environmental Protection Funds" ensure that environmental protection and governance funds have an important source. Some provinces, municipalities and districts have also formulated corresponding regulations. Among them, the Fujian Provincial Economic Commission, the Department of Finance, the Environmental Protection Bureau and the Coal Industry Corporation promulgated in 1990 on the collection, use and management of coal mine ecological environmental protection fees. The Notice of Work is a regulation directly related to the economic policy of mine environmental protection, and its relevant regulations are worth learning.
(IV) Policy Regulations and Standards Related to Mine Environmental Protection In terms of mine environmental protection, there are no specific policy regulations in China, which are stipulated in relevant provisions of relevant laws, regulations and rules.
Various industrial departments have formulated some policy regulations related to mine environmental protection, such as: "Notice on Establishing a Sound Environmental Protection Agency", "Several Provisions on Environmental Management of Metallurgical Industry", "Implementation Measures for Metallurgical Environmental Protection Indicators", Regulations on Environmental Protection of Building Materials Industry, Regulations on Radioactive Waste Management of Uranium Mines, Safety Design Regulations for Tailings Reservoir of Uranium Water and Metallurgical Plants, Interim Regulations on Environmental Management of Chemical Industry, and Regulations on Environmental Monitoring of Chemical Industry.
In addition, in some local regulations, some provisions are related to mine environmental protection. Such as; "Sichuan Province Environmental Protection Regulations", "Yunnan Province Urban and Rural Collective Individual Enterprises Environmental Protection Measures", "Hunan Province Solid Waste Management Measures", "Shanxi Province Weihe River Basin Water Pollution Prevention and Control Regulations", etc.; It is a regulation specially formulated for mines, such as the Notice of Guangdong Province on Reorganizing Existing Quarries and Strengthening the Management of Quarry Industry, and the Interim Provisions on the Management of Salt Mine Resources in Yunying Area of ​​Hubei Province, Yunnan Province. “Regulations on Collective Mining Enterprises, Private Mining Enterprises and Individual Mining Management in Yunnan Province”, “Regulations on Mine Geological Environment Protection in Yunnan Province”, “Regulations on Collective Ownership of Mining Enterprises, Private Mining Enterprises and Individual Mining Management in Jilin Province”, etc. .
Relevant mine environmental standards such as atmospheric environmental quality standards, urban regional environmental noise standards, surface water environmental quality standards, industrial furnace kiln dust emission standards, non-ferrous metal industrial solid waste pollution control standards, etc.

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