Principles and technical contents of mine ecological restoration

3. Wetland ecological restoration model in "wet beach area" of tailings pond

Most of the metal mine tailings ponds adopt the wet discharge technology, and its tailings have high water content. However, the overall comprehensive utilization level of tailings in China is not high at present, which leads to the existence of a large number of tailings ponds for a long time after the mine is closed. In some tailings ponds located in gullies, due to the inflow of surface water and groundwater and the difficulty in removing the water in the tailings, perennial water accumulation or swamping is formed. At this time, wetlands should be retained according to local conditions and plants with "acid, weight and water resistance" should be planted on the surface for restoration.

(4) Ecological restoration mode of mine construction land

The ecological restoration of mine construction land is mainly engineering restoration, and the content of biological restoration is less. Its ecological restoration mode mainly includes: mining cave-in backfill area, open mining mountain chassis area, mining industrial square construction land ecological restoration.

1. Ecological restoration model of construction land in mining subsidence area

As the subsidence area of many well mining hills is located in the urban built-up area or planning area, the surrounding infrastructure is relatively perfect, and the urban development has the demand for construction land, so the ecological restoration model is adopted as the construction land. The ecological restoration project in this mode is mainly a "geotechnical" project. By taking ground backfill and foundation treatment measures to the mining subsidence area, the mining subsidence backfill area can meet the requirements of construction land.

This restoration model has been widely used in Huainan, Huaibei, Tangshan and other places in China. The landfill project in Huainan coal mining subsidence area adopts a series of remediation measures such as horizontal seepage prevention, vertical seepage prevention, landfill gas management, environmental monitoring, and ecological restoration. The total investment of the project exceeds 96 million yuan. After comprehensive treatment, the former "garbage mountain" has undergone beautiful evolution and become an ecological park with fitness, leisure and spectacular scenery.

In mid-October 2018, during the review and inspection of the World Bank inspection team, Mr. British International Municipal expert. Christopher Banes, who has been to more than 50 countries in more than 40 years of work at the World Bank, gives high marks to the landfill closure project in Huainan as the best clean-up project he has seen. At the same time, the project won the third prize of science and Technology of China Urban Environmental Health Association.

2. Ecological restoration model of construction land in open mining chassis area

The underbed area of open mining mountain is generally a relatively gentle zone with a certain area, especially large open mining mountain. The restoration mode of underbed area is mostly woodland or dry land. However, the underbed of open mining mountain with a large area located near the urban area or in the suburbs with convenient transportation will also be restored as a construction land as a choice.

3. Ecological restoration model of construction land for industrial square, waste dump, waste rock dump and living area

All kinds of mining industrial squares, as long as the infrastructure is easy to support, can be used as construction land repair. Safety coal pillars are reserved in the industrial squares of coal mining mines, the surface is stable, and only the construction structures need to be dismantled, which can be directly used as construction land. If the coal seam mining collapses in the industrial squares, it needs to be used after restoration works; Some large mining living areas themselves have perfect infrastructure construction, and can be completely retained as construction land after the closure of the pit, without investing too much restoration projects.

Beijing Lujiashan Circular Economy Industrial Park is a representative of such projects. The construction of the park uses post-mining pits to optimize site conditions through ecological restoration and other means, and plans to build solid waste treatment facilities such as domestic waste incineration, kitchen and construction waste, supplemented by education centers, scientific research centers and environmental parks. Build a national circular economy (vein industry) demonstration base. The project covers an area of about 2100 mu, with a total investment of about 4.6 billion yuan.

(5) Ecological restoration mode of Mine Mountain Park

The mine is the source of mineral resources and the site of mining activities, which promote the development of human civilization. After the end of mining, the abandoned land of mining and mining and other facilities occupy an area, which is called mining relics. It is a historical witness of human mining activities in different ages, and part of it can become a historical and cultural heritage with important value. The construction of mine park is also a new ecological restoration model for the large area subsidence area near the city.