One, the current situation
1, mine classification
In the city of all 112 mining enterprises, in addition to five engaged in the extraction of groundwater water company, the rest of the enterprises from the mining method can be divided into two kinds of: open-pit mining and cave mining. The enterprises adopting cave mining are mainly coal mines, gypsum mines, clay mines and other enterprises, and there are 59 of them in the city***. Take open-pit mining is mainly limestone mines, quartzite mines, basalt mines, shale (sand) rock mines and other enterprises, **** there are 48. From the type of mineral products can be divided into the following seven main: coal enterprises, gypsum enterprises, clay enterprises, limestone enterprises, quartzite enterprises, basalt enterprises, page (sand) rock enterprises. Specific statistics are as follows: 34 coal mines, 10 gypsum mines, 16 clay mines, 17 limestone mines, 7 quartzite mines, 7 basalt mines, 16 shale (sand) rock mines, as for the other classifications, due to the focus of this paper is not the focus of this article, will not repeat here.
2, the amount of mine erosion
The city is located in the southwest of the Sichuan Basin, is a hydraulic erosion area. Although more types of mining enterprises, but analyze the degree of soil erosion should be mainly according to the mining method as a measure of the amount of soil erosion as much as the main factors.
Cave mining due to this type of mining only in the hole digging, in addition to the main shaft and wind shaft entrance to the surface damage, and part of the temporary production room occupies part of the surface. This type of mining is less destructive to the surface, and the amount of soil erosion is relatively small.
Open-pit mining open-pit mining is the most destructive to the surface. In mining operations in order to obtain the mineral products under the topsoil, you must first remove the topsoil, which will inevitably destroy the surface of the trees, shrubs, turf and other surface attachments, the native surface of the soil and water conservation facilities caused by the damage, to varying degrees exacerbated the degree of soil erosion. While destroying the water conservation facilities, a large amount of abandoned soil and slag will be generated. This type of mining will not only cause serious damage to the surface, but will also produce a large amount of soil erosion.
3, mine soil erosion of several types and cause harm
(1), water pollution A larger part of the mining enterprises to take the cave mining method, in the mining process is often for the purpose of dust reduction and other artificial spraying water or cave originally have spring water. Although the source of water may be different, but in the mining water quality are extremely vulnerable to pollution, mainly in the presence of suspended solids, color and other water quality indicators exceeded. Water pollution is caused by the fact that the water is discharged directly out of the cave and into the rivers and ditches largely untreated. This kind of phenomenon especially coal, gypsum enterprises occur most.
(2), the destruction of vegetation in the hole mining method of mining enterprises in the production process, the main well and wind wells and temporary production in the construction of the building, inevitably destroy part of the forest and grass, reduce the damaged surface of the soil and water conservation function, to a certain extent, exacerbate soil erosion. And in the open pit mining enterprise production, due to the stripping of topsoil, it is bound to destroy the surface of the trees, shrubs, turf and other surface attachments, the native surface of the soil and water conservation facilities caused by damage, to a large extent, exacerbated the degree of soil and water erosion in the mining area.
(3), slag
Both cave mining and open pit mining enterprises, in its production process will produce a large number of abandoned soil, abandoned slag. And produce the abandoned soil, abandoned slag and often arbitrarily with the slope on the ground piles, piles of slag below neither retaining walls, above and no cut-off, drainage ditches, every big rainfall, it becomes a source of soil erosion, while the abandoned slag piles in the rainwater infiltration of its anti-slip stability will be greatly reduced, is very prone to cause landslides and mudslides, endangering the pile of body below the building and the people's life safety. We are in the mine water law enforcement inspection of various types of mining enterprises in the annual production of slag to do the following estimates:
Coal production: an annual output of 30,000 tons of small coal mines, for example, the amount of waste gangue according to the coal production of 20-30% of the calculation, the amount of slag produced annually between 6,000-9,000 tons. The city's 34 coal mining enterprises produce about 204-288,000 tons of slag per year.
Gypsum and clay production: gypsum production are used in cave mining, the amount of slag is smaller, but according to the actual step-by-step estimation of 400-600 tons per year, the city's 26 gypsum enterprises in the city's annual production of slag is about 10,400-15,600 tons.
Limestone, quartzite, basalt, shale (sand) rock production: the city's 47 of these four types of mining enterprises with an annual production scale of 3.285 million tons, the amount of slag disposal to the production scale of 20-30% of the calculation, the amount of slag produced annually is about 657-985,500 tons. Take Emeishan Jinshan Gypsum Mine as an example: the mine was originally a state-run enterprise, and was transformed into a private enterprise in 2002. The planned annual production capacity is 150,000-200,000 tons. The former production of slag from blasting gypsum mining waste rock and stripping of pumice cover caused by a large number of discarded soil and stone, according to the geological department to provide information on the survey stripping ratio of 0.4:1, 92,000 tons of slag produced annually.
Through the above estimates can be roughly derived from the city's mining enterprises annually generated by the abandoned soil slag volume of about 871,400-1,289,100 tons. Such a large amount of abandoned slag, unstandardized stacking methods, for the generation of soil erosion provides a large number of material sources, greatly damaging the local ecological environment.
II. Countermeasures
1. Countermeasures
For different kinds of soil erosion, different measures should be taken to manage it.
Water pollution Due to the mining process caused by the sewage is mainly presented as suspended solids, chromaticity and other water quality indicators exceeded the standard, the solution to such problems can be classified by different treatment methods. Suspended solids in the water exceeds the standard of the problem, you can build a multi-group sand filter pool, pool filter body using different particle size of sand and pebbles. The chromaticity of the polluted water exceeds the standard, should use simple water treatment equipment to purify, so that the treated water to meet the requirements of the national comprehensive sewage discharge standards, that is, in the discharge into the GB-3838 three types of waters of the sewage after treatment to achieve the first-class discharge standards, in the discharge into the GB-3838 four, five types of waters of the sewage after treatment to achieve the second-class discharge standards. Specifically treated sewage discharge of suspended solids and color index standards are as follows: (GB8978-1996)
One level of standards: color <50mg/L
Suspended solids (mining, mineral processing, coal processing) <100mg/L;
Second level of standards: color <80mg/L
Suspended solids (mining, mineral processing, coal processing) <<300mg/L 300mg/L
Vegetation restoration The destruction of surface vegetation caused by mining is handled according to its situation. In addition to the land permanently occupied, the land occupied by temporary production houses should be planted with trees or grass after the end of occupation. For the surfaces of abandoned and unused mining workings and piles of dumped soil and slag, trees or grasses should also be planted on soil covered with 20-30 centimeters. In the inspection, we found that is located in Huangwan Township, Heishui Village, JiangYaJi coal mine in this aspect of the successful experience, the mine owners in the abandoned gangue pile directly planted poplar tree has achieved success, the current planted poplar tree diameter has been in the 2-3 centimeters, good growth. Doing so not only greening the abandoned slag, but also increase the stability of the abandoned slag, and there is a certain economic benefits, can be said to be three in one.
Discarded soil, slag disposal As mentioned earlier, the city's mines produce a large number of annual slag disposal is also a headache. For the abandoned slag, we suggest the following two measures: first, transportation. Due to coal mine production in the waste gangue and thermal power plants and gangue brick factory production used in the raw materials, so it is recommended that the owners of coal mines will be transported and sold gangue to the city within the Minjiang River Thermal Power Plant and the main gangue brick factory in Sichuan. For the remaining gangue can not be transported away in search of suitable places to standardize the stacking. Due to the stacking place in the hillside, so it is recommended that the owners of the pile of body below the construction of retaining walls, walls to leave drainage holes. Pile body above the construction of cut-off, drainage ditch, in a timely manner, the slag field upstream of the rain catchment area generated within the precipitation drain, to ensure the stability of the pile body. In addition to abandon the slag pile body to mulch planting grass and trees, improve the surface of the function of soil and water.
2, financial security
To carry out a good mining enterprise soil erosion control work, there must be sufficient financial security. From the city's actual situation, soil erosion funding sources are the following two: First, in line with the "who destroys, who governs," the principle of technical strength of mining enterprises, self-financing by the owner of the technical guidance in the municipal water conservation department to carry out their own governance; Second, does not have the appropriate technical force, unable to manage the enterprise, by the municipal water conservancy bureau. In accordance with the provisions of the law, the collection of its soil erosion prevention and control fees and compensation for soil and water conservation facilities. In the city's collection of water conservation "two fees" in accordance with the severity of soil erosion, in line with the principle of first urgent and then slow by the Municipal Water Resources Bureau to organize a planned governance.
3, technical support
Mine erosion control is a comprehensive, highly technical work, there must be a professional team of water control engineering planning, design and technical guidance to ensure that soil erosion control work smoothly. From the city's existing water conservation industry technical force, the city of water conservancy and hydropower construction survey and design enough to provide technical support for this work. In addition, the Municipal Water Resources Bureau plans to carry out annual targeted training of mine personnel, mine personnel to carry out soil erosion control good exchange of learning in the county, to improve the management of soil erosion awareness of mining enterprises. Municipal Water Resources Bureau will provide industry management and technical guidance for the city's mine erosion control, so that the city's mine erosion control work on a healthy and orderly development track!
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