Qi Dashan Iron Mine abandoned land reclamation mode

Anshan City is a large-scale industrial city developed by relying on iron mining and steel industry. It is a famous old industrial base and mining base in China, and is known as the “Golden Capital of the Motherland”. In the decades of large-scale mining, the total area of ​​land destroyed by mines in the city reached 170 km ² ; geological disasters and hidden dangers existed in large numbers; artificially stacked slopes such as huge discharge yards and tailings ponds are potentially harmful; iron mining The dust makes the atmospheric dustfall in Anshan City remain high; the huge open pit drainage and drainage and mineral water pollution have greatly changed the original groundwater quality and water cycle. Qi Dashan Iron Mine is the largest iron ore mine in Asia. Its rock-discharging field is only 6km away from the urban area of ​​Anshan. It is of great scientific and practical significance to summarize the model of Qi Dashan mine reclamation. The research work in this paper can provide a typical example for the reclaiming work of iron ore mines in China, and provide a scientific basis for the sustainable and coordinated development of mining cities.

I. Status Quo of Qi Dashan Mine

Qi Dashan Iron Mine is located in Anshan City, Liaoning Province. It is an artificially reconstructed landform with a low elevation of 200m. It is now buried in the original terrain due to long-term artificial accumulation. The zone is a warm temperate continental monsoon climate. During the same period of rain and heat, it can fully meet the water and heat demand suitable for plant growth. The surface water is mainly Nansha River, Yunliang River and Yangliu River. The groundwater type is mainly bedrock fissure water and fracture fissure. Water; the soil type is mainly brown soil, and the sedimentary field in the area is mainly composed of magnetite quartzite , granite and granulite; the main vegetation community is Pinus tabulaeformis, Pinus tabulaeformis, broad-leaved forest and grass community, artificial The vegetation is mostly pear forest, chestnut forest, apple forest and so on. The disastrous weather in the mining area is mainly spring drought, heavy rain, collapse, landslide, mudslide, soil erosion, hail, wind and dust.

Qi Dashan Iron Mine is one of the three mining enterprises under the Angang Group. It is currently the largest iron ore mine with the highest level of modernization in China. The mining area is 7km away from the city center, including within the urban planning. The existing proven reserves total 163,388,000 tons, and the annual output is 9.21 million tons. The total area of ​​the Qi Dashan mining area is 13.64 km ² . Except for a small part of the mining area used for production and construction and roads, all of them are mining and drainage treatment sites, mining pits and other industrial and mining wasteland (Table 1).

2. Limiting factors for reclamation of abandoned land in Qidashan Iron Mine

There are a series of problems in the process of reclamation of Qi Dashan Mine. The resolution of these key problems is closely related to the implementation and effect of mine reclamation. The specific limiting factors for the reclamation of the Qidashan iron ore abandoned land are as follows:

(1) The surface of the iron ore abandoned land is bare and the gravel is exposed, and the vegetation cannot grow. The reclamation area is the mining pit of the mining and the mining pit of the ore mining. The quarrying field is mainly the round-story laminated pile formed by the discharge of abandoned rock blocks, and the mining pit is the large exposed pit of the exposed body rock, the rock discharging field and There is no topsoil suitable for vegetation growth in the pit body, and the vegetation cannot grow.

(2) The terrain of the reclamation area is complex and it is difficult to rehabilitate. Most of the reclamation project areas are dumping sites of abandoned rock with a mining stripping diameter of 30 cm or more. In the mine development, the landform of the reclamation area is completely destroyed, the terrain is undulating, the order is steep, the slope is steep, and the construction of the reclamation is difficult. Big.

(3) The matrix of the rock discharge yard has poor water retention and poor soil conservation, which is not conducive to the growth of vegetation. The rock-discharging field is a pile of abandoned rock blocks with large block diameter and strong water permeability. Planting vegetation on the rock-discharge field requires a large amount of water to ensure the water needs for vegetation growth. Due to the large gap between the abandoned rock blocks, when the vegetation is watered, the soil is easily lost along the gap between the rock blocks, which is not conducive to the reclamation of vegetation.

(4) The infrastructure of the reclamation area is seriously damaged and the reconstruction is difficult. In the mining, the original infrastructure was completely destroyed, the current status of the landform was extremely complicated, and the reconstruction of infrastructure such as transportation and water supply was more difficult. It is the key and foundation for the reclamation of the Qidashan iron ore abandoned land to better remove the restriction factors of the reclamation process in the mine reclamation process.

Third, Qi Dashan mine reclamation mode

Mining exploitation will cause serious damage to the surface landscape. The mine reclamation in China began in the 1970s, and the extensive mine reclamation began in 1988 when the Land Reclamation Law was promulgated. The land reclamation in the mining area refers to the remediation measures for the land damaged by the excavation, collapse, and pressure occupation during the mineral mining process, so that it can be restored to the available state. The main purpose of land reclamation in mining areas is to reopen land that has been destroyed, restore its intended use value, and eliminate or prevent various hazards caused by land destruction. Land reclamation is the core content of restoring mine ecological environment in iron ore districts, and its effects can be used as indirect indicators for soil animals and soil microorganisms.

According to the principles of geosciences, environmental science, ecology, agronomy, aesthetics and systems science, we fully consider the various factors in the natural and human systems and their interactions, and establish the abandoned land of Qidashan Iron Mine as forest. The reclamation mode combining garden, irrigation, grass and fishery can be refined as follows: flat garden, water conservancy, grass slope, and low fish pond (Table 2).

The specific contents of the reclamation mode of the Qidashan iron ore abandoned land include:

(1) Flat ladders and piles of water. The objects of mine reclamation are mainly mining pits and quaring fields. The abandoned rock in the front of the reclaimed quarry is surrounded by a number of first-order platform quarries. Most of them are stacked in a stepped truncated cone shape. The number of stages is different, generally between 3-5 steps, the height of the step is between 20-40m, and the width of the safety part of the ladder platform is 24m when the ore is mined. The actual width is different. The whole body of the table is bare and uneven. . The mining production pits in the mining production are generally elliptical funnels, spiral-stepped from bottom to top, the bench tops are narrow, the rock is hard, the number of steps is large, and the original design step height between the steps is 12m, which is practical. The economic forest land, garden land and shrub land reclamation area retain the natural slope of each natural rock drainage field, and the large leveling machinery and equipment are used to level the ladder platforms of the rock discharge field. After the leveling, the platform platform covers the stripped soil (Table 3, Table 4). . A stone intercepting edge is built on the platform as a skeleton for building a water cut. The water cut edge is 30cm wide and the bottom width is 200cm. The bottom edge of the water cut edge is 10cm, and the slope of the outer slope is flush with the corresponding step slope. The slope of the slope is 40°, and the height of the water cut is 20cm above the plane of the passenger layer.

(2) Transfering soil and covering land. Mine reclamation takes the form of guest soil overburden, and the source of the land is of vital importance. In the mining of Qi Dashan, it is necessary to strip a large amount of topsoil of the mountain. The reclamation area uses these topsoil as the source soil. According to the mining plan, the normal mining of the mine in the next two years requires the stripping of the surface soil of 12.127 million tons, and the stripped mountain topsoil is clayy soil. The soil is firm and the soil organic matter content is also high, generally ranging from 1.45% to 1.57%. It is suitable for the growth of forest trees, fruit trees and weeds. The quantity and quality of the soil sources can meet the needs of reclamation in the project area. After the leveling of the mining site and the rowing platform, the step platform surface and the step slope surface cover the stripped guest soil, and the thickness of the covering should be determined according to the different crops to be planted.

(3) Digging shallow pits and applying fertilizers. A shallow pit of 50cm × 5Ocm × 50cm is dug on the stepped platform and slope surface of the covered land, and the replanted vegetation is planted. Slope digging should firstly organize the control point into a small platform, dig holes on the platform, and dig the large stones as much as possible in order to expose the fine particles. The reclamation area uses soil baskets to fill the soil, and mixes the water retaining agent organic fertilizer in the guest soil. The degradable bag is placed in the soil basket to prevent extravasation and water loss of the guest soil, ensuring the water retention and fertilizer retention capacity of the guest soil. Soil compaction, and finally the nutrient cup seedling with the best test effect is implanted into the pit, and cover the appropriate amount of soil and straw to ensure the quality of vegetation restoration.

(4) Flat-planted wood and sloping vines. The comprehensive utilization of reclamation land should adhere to the principle of adapting to local conditions, agriculture, agriculture, animal husbandry, and fishery. Covering the stepped platform and slope surface of the mining stope and rock discharge field after leveling, as the land for agricultural production and ecological vegetation restoration, the crop should select drought-tolerant and barren-resistant varieties, taking into account economic benefits. The organic combination of various crops such as Joe, Irrigation, Grass and Rattan should be effectively restored (Table 5), and the important role of biodiversity in restoring the ecological environment of the mine should be brought into full play. Middle-aged, young seedlings are planted, and herbaceous crops are properly mixed. Among them, the herbaceous plants are mixed with native weeds, and the grasses are mixed and sown. The overall green area of ​​the reclamation area is planned to reach 70%, and the forest belt around the mining area will be realized. The forests on both sides of the mine will be shaded, the open space of the mining area will be gardened, and its good ecological landscape will be reconstructed. The mining activities will be perfectly integrated with the surrounding environment to form an ecological industry. Sightseeing area.

(5) Lifting water and building water stations. The main irrigation water source in the reclamation area is the water for collecting fishery ponds constructed by the dewatering water of the mine pit and the negative elevation area of ​​the mine pit. The deepest part of the mining pit in Qidashan mining area is below -75 m above sea level. It has reached the pore water, karst water and bedrock fissure water layer of underground loose rock. The water quality is good. The water in the pits during the flood season and dry season basically meets the vegetation. Water demand. Irrigation adopts the method of lifting irrigation to build a secondary water lifting station, one for each of the first and second water lifting stations, the central part of the quarrying field and the top of the reservoir. The design flow of Qidashan Water Lifting Station is 280m ³ /h, and the water storage capacity of the water storage station is 1009m ³ . The total water storage station is built at the highest point of the project area, diverting the water source to the sub-storage pool, the bottom of the pool is set with a gate valve, and the hose is connected to the self-flow irrigation reclamation area. The irrigation area is connected with the detachable soft rubber hose to connect the reservoir gate valve, and the spring and winter seasons are socketed. The water is watered, recovered in the rainy season and winter, and the length of the hose is 60-100m. At the same time, the water tank can be configured to assist watering.

(7) Keep the road and repair the disc. The reclamation area is located in the old mining area, the original main road is complete, the road surface is hard and the distribution is reasonable. The project area is hard and the bulldozer can be simply shoveled along the mountain. The road is mainly for agriculture and forestry production services. Retain the original main road, build the Panshan branch road leading to economic forest land and orchard along the terrace platform of the rock quarry, and plan to design a hardened road with a width of 4m to ensure the construction and other production operations: other shrub areas and vegetation restoration. The area will be built with a 3m wide hardened branch road to ensure the construction and forest protection and fire protection needs in the early stage of planting.

Fourth, the conclusion

(1) The Qi Dashan reclamation model fully considers the human and natural factors of the mining area, organically integrates the natural system and the social system, improves the harsh ecological environment of the mining area, and promotes the social, economic, resource, and cup system of the mining area. Sustainable development, with the goal of coordinated development of complex mine systems, has significant social, economic and ecological benefits.

(2) The limiting factors of Qi Dashan reclamation mainly include the bare body of rock and gravel, large gap between rock blocks, and poor water retention and soil conservation. These factors are not conducive to the growth of reclaimed vegetation. The terrain of the reclamation area is extremely complicated, the construction of reclamation is difficult, and the reconstruction of infrastructure is difficult. The lifting of many restrictive factors has become the key to mine reclamation. The solution of these key problems in Qi Dashan reclamation project can provide reference for other metal mines in China to overcome these problems.

(3) The reclamation mode of the abandoned land of Qidashan Iron Mine is a combination of forest, garden, irrigation, grass and fishery. It can be refined as follows: flat garden, water conservancy, grass slope, and low fish pond. The specific contents include: flat ladder, pile of water; moving soil, covering land; digging shallow pit, applying fertilizer; flat seeding, slope planting vine; lifting pit water, building water station; Leave the road and repair the disc.

(4) The reclamation mode of Qidashan Mine can provide theoretical and practical basis for metal mine reclamation, and play a good demonstration and promotion role for the recovery of metal mines in China. It has extremely important reference value, the example itself and its The research and resolution of a series of scientific issues in the implementation process has great scientific and practical significance.

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