Mine environmental treatment method and ecological restoration technology

I. Status of mine environmental management and ecological restoration

1. Overview of mine environmental management and ecological restoration

Mine environmental management and ecological restoration mainly use man-made engineering means or measures to create suitable soil environmental conditions for regional vegetation growth on the abandoned bare slope of the mine with poor vegetation restoration. At the same time, the pioneer plant community was introduced to cover the bare ground in the early stage, so as to avoid desertification and soil erosion in the mine wasteland, and lay the foundation for the formation of the target community in the later stage.

2. Status quo of mine environmental management and ecological restoration

In the course of nearly ten years of development, the mining industry in China has developed rapidly, and the mining industry has also risen in the national economy, and has achieved outstanding economic benefits. However, as the mining of mineral resources is the most large-scale human activity that changes the surface landscape and destroys the surface ecosystem, China's large-scale mining has caused great damage to the land environment in our country, prompting the sharp reduction of land resources around the mining area. At present, the total number of mines in China is more than 20*104, which is widely distributed in economically underdeveloped areas and remote areas. Due to the backward technology of small-scale mining activities and the lack of standardized management system, there is a serious waste of resources. The loss of control of the overall mine management has also exacerbated the damage of the mine to the soil. The ecological restoration rate of most mining areas in China is about 0. In this case, if small-scale mines are not effectively managed in time, the overall ecological restoration rate of mining abandoned land will be affected.

To some extent, China's mine environmental management and ecological restoration are mostly the way of ecological reconstruction. At present, the ecological reconstruction of mine in China is mainly aimed at the mined-out area, tailings site, waste site and subsidence area caused by mining activities. The main ecological reconstruction methods in the goaf of open-pit mining mines are natural vegetation restoration and artificial vegetation restoration. In combination with water storage reconstruction, deep digging technology and agriculture and forestry reconstruction, vegetation recovery can be accelerated. The ecological reconstruction of tailings field mainly uses the way of artificial afforestation, through the ecological reconstruction of gangue and subsidence area, to promote the ecological restoration. The main technologies used in the ecological reconstruction of the dump include soil vegetation restoration, soil stabilization and vegetation species screening and allocation. The ecological reconstruction of subsidence area is mainly based on the development direction of mining subsidence area after reconstruction, comprehensive consideration of agriculture, aquaculture, construction and other factors, to formulate the corresponding ecological reconstruction plan.

Ii. Mine environmental management and ecological restoration ecological environmental effects

1. Hydrogeological changes and regional water pollution

In the process of mining, the occurrence of problems such as mine drainage, mine cracks and collapse will directly affect the change of underground water storage structure of mining module, and then lead to the decline of groundwater level, the emergence of large area of dredging funnel, surface runoff change and other problems. In addition, the discharge of industrial wastewater such as pit water and wastewater leaching water during the mining stage has caused serious pollution to the water source around the mine .

2. Increased probability of geological disasters

The development of mining operations will inevitably lead to underground mining problems. The occurrence of underground mining problems will not only affect the stability and safety of the mountain and slope around the mine, but also aggravate the probability of ground cracking, collapse, landslide and other accidents. In addition, a large amount of waste residue discharged from mining is deposited on hillsides and gullies, and the mixing of waste rock and waste slag with soil will directly lead to the reduction of friction and water permeability of waste rock and waste slag. If there is heavy rain at this time, it will increase the probability of debris flow.

3. Soil pollution and degradation

After mining, the topsoil needs to be removed and covered with new soil or slag, and the heavy load of large mining equipment during the mining process will cause the slag or new soil to gradually harden and harden. In addition, the subsidence of mining ground and the discharge of solid waste will directly lead to cracks in the soil. With the expansion of soil cracks, soil nutrients will gradually be lost, and the toxic components in mine solid waste will directly penetrate into the soil, resulting in serious acid and base pollution, heavy metal pollution and organic toxic substances pollution.

4. Soil erosion intensifies

In the process of mining, the surface vegetation will be destroyed directly due to the excavation of open pit and the extraction and drainage of underground water. Then the groundwater level in the mining area is greatly reduced, and a large area of artificial bare land is gradually formed. At this time, if there is a large area of rainfall, it will accelerate the flow of surface water under the action of mine ground fluctuation and grooves, and finally promote the intensification of soil erosion.

3. Influencing factors of mine environmental management and ecological restoration

3.1 Soil factors

Soil is the prerequisite for the normal operation of mine environmental management and ecological restoration, and is also the key factor for the survival and growth of vegetation on the surface of the lithosphere. It can not only provide the mineral elements and water required for the survival and growth of vegetation, but also provide carriers for the mutual operation of biological parts and inorganic environments in the ecosystem. In this case, the pH value in the soil, soil structure, parent material, nutritional status and other factors directly affect the effect of mine environmental management and ecological restoration.

3.2

Light intensity

Light intensity is the main energy provider of vegetation photosynthesis in mining area. According to the difference of light intensity, the environmental management personnel of mining area can choose the appropriate ecological restoration vegetation types, such as shade-tolerant plants, positive plants, etc., to ensure the ecological restoration effect.

Temperature can affect vegetation growth activity through two channels: air temperature and ground temperature. The activity of vegetation growth directly affects the efficiency of environmental management and ecological restoration in mining areas.

Water is the key factor for the normal survival and growth of vegetation, and is also the main element involved in photosynthesis and respiration of vegetation. It can provide a good channel for the absorption and transport of mineral nutrients in vegetation. The water supply of vegetation also directly affects the effect of environmental management and ecological restoration in mining areas .

3.3

Temperature and moisture

Temperature can affect vegetation growth activity through two channels: air temperature and ground temperature. The activity of vegetation growth directly affects the efficiency of environmental management and ecological restoration in mining areas.

Water is the key factor for the normal survival and growth of vegetation, and is also the main element involved in photosynthesis and respiration of vegetation. It can provide a good channel for the absorption and transport of mineral nutrients in vegetation. The water supply of vegetation also directly affects the effect of environmental management and ecological restoration in mining areas .

4. Typical technologies of mine environmental management and ecological restoration

4.1 Typical technologies of mine soil pollution control

4.4.1

Topsoil conversion and guest soil cover

Topsoil conversion is mainly in the early stage of mining operations, operators can first dig the surface and subsurface soil, and store in a suitable environment. At the end of mining operations in the mine area, the previously stored soil is returned to its original place. Although the above methods destroyed the preparation around the mining area to a certain extent, the overall soil physical properties, seed bank and nutritional conditions did not change greatly, which could facilitate the growth and survival of native plants in a short time.

When the soil thickness of abandoned land is insufficient after mining, the cover of guest soil is fixed in the surface soil of abandoned land after mining. In addition to improving the physical and chemical properties of the abandoned soil after mining, it can also provide good conditions for the preparation and reconstruction of the abandoned land by adding microorganisms, nitrogen and plant seeds to the guest soil.

4.1.2

Improvement of soil physical properties

The main purpose of improving the physical property of mine soil is to improve the soil porosity in mine wasteland. In the short term mining area soil physical property improvement operations, mining area environmental management personnel can use plowing, or the application of farm fertilizer to reduce soil bulk density, improve the mining area abandoned land soil structure. At the same time, for the soil environment of the mining area with poor pH, the environmental management personnel of the mining area can use quick lime or bicarbonate to adjust the pH to increase the calcium content in the soil.

4.1.3

Soil chemical properties improvement

It is a long - term project to improve the soil chemical properties of mining wasteland. Therefore, on the basis of the application of chemical fertilizers and nitrogen-fixing plants, the environmental management personnel in the mining area can adopt appropriate microorganisms to regulate and control the heavy metal pollution and organic waste pollution of the soil in the mining area.

4.2 Typical techniques of mine vegetation restoration

4.2.1. Vegetation growth rolling cover method and high and steep rock slope greening method

The vegetation growth rolling method is mainly applied to the soil slope with slow slope and low slope, and the local turf is used for planting. It can form target population in a short time.

The greening method of high and steep rock slope is mainly through planting the substrate of sustainable growth of vegetation on the surface of mine slope. The matrix is fixed on the surface layer of rock slope after mining excavation for a long time. At the same time, according to different geological conditions, the vegetation species selection and outdoor growth experiment were carried out by using the solid soil slab structure made of waste straw to ensure the greening effect of high and steep rock slopes.