Study on ecological restoration status and treatment countermeasures of abandoned mines left over from history

China has about 800,000 mines, of which about 400,000 are in need of restoration due to ecological damage. The "China Mineral Resources Report (2020)" and the "2020 Coal Industry Development Report" pointed out that about 40% of the old problems have not been treated, but the annual control rate of newly damaged land is only about 40%. In the early stage of economic development, the mining development mode is simple and extensive, and the environmental pollution control is not paid enough attention. After the establishment of the Ministry of Land and Resources in 1998, the state level supported the restoration and management of mining geological environment. In 2006, the Ministry of Finance, the Ministry of Land and Resources and the State Environmental Protection Administration jointly issued the Guiding Opinions on Gradually Establishing the Responsibility Mechanism for Mine Environmental Management and Ecological Restoration, which put forward the basic ideas of the deposit system for mine geological environment restoration and management. The difficulty of mine environmental management is the low level of restoration technology and the relative lack of professional personnel.

In order to solve the outstanding problems existing in the process of ecological restoration of mines, national and local policies have been introduced, for example, Notice on carrying out the National Verification Work of Historical Mines, Opinions on Exploring the use of market-oriented methods to promote the ecological restoration of Mines, Notice on Supporting the ecological restoration Demonstration Project of Historical abandoned Mines, Measures for the Implementation and Management of Ecological Restoration of Mines in Shandong Province, Action Plan for Comprehensive Management of Mines in Hebei Province, and on Strengthening the control and protection of mineral development Decision of state environment, etc. According to the overall framework of ecological civilization construction, follow the principle of government-led and market operation, encourage social capital to participate in the ecological restoration and management of mines through concept changes and policy guidance, adopt a systematic, scientific and standardized governance model, improve the ecological restoration capacity of mines, and achieve the ecological restoration goal.

The abandoned mines left over from history destroy the natural landscape, and there are hidden dangers of geological disasters such as landslides and collapses. The environmental pollution caused by mining reduces the local biological population, so it is imperative to restore the ecological management of mines. There are many deficiencies in the main aspects of the restoration system, such as the restoration mechanism, the restoration fund, the restoration mode, the restoration project, and the restoration technology, which lead to the low quality and slow speed of the restoration. Therefore, summarizing the problems of the mine ecological restoration and putting forward targeted measures and suggestions are conducive to forming a complete mine restoration system and accelerating the progress of the mine restoration.

l. Management status of historical mines

1.1 Large inventory and heavy task

Remote sensing survey and monitoring data show that by the end of 2018, the country's mining occupied about 3.60×l04km2 of damaged land; The land occupied and damaged by historical and mining mines is about 2.27×l04km2 and 1.33×l04km2 respectively. The storage of solid waste such as state-owned tailings ponds and waste slag fields occupies a large amount of land, and many environmental problems are left after private mining. Most of the mines left over from history are small and medium-sized mines with disorderly exploitation and scattered distribution, which have serious ecological damage and wide influence. Mine restoration is a complex systematic engineering, involving geology, hydrology, environment and many other aspects, the engineering amount is huge, the restoration period is long.

1.2 Strong governance needs

Mining is mostly open-pit mining, the mountain and vegetation damage is more serious, the natural habitat of wild animals and plants is damaged, the mountain collapse and landslide, flash floods and debris flows and other disasters occur from time to time, seriously affecting the life of the people around the mining area. To restore the geological environment and ecological environment of the mine, control the pollution caused by mining, and make it coordinate with the surrounding natural environment, the public has an urgent need for the treatment of abandoned mines. In 2021, the second round of central ecological environmental protection inspectors received a large number of complaints from the masses about pollution caused by mining, some mines illegally occupied woodlands, large areas of mountains were exposed, dust polluted the atmosphere, heavy metal polluted orchards and other serious phenomena, which have been reported on the official website of the Ministry of Ecology and Environment as typical cases of inspectors.

1.3 Low land reclamation rate

Some developed countries have a long history of mining, and their governance concepts, measures and technologies started earlier. Since 1940, Germany has been reducing the destruction of the ecological environment in the mining process, while taking into account the ecological changes and residents' requirements for the environment from a macro perspective to carry out mine restoration and management. After 1960, some countries began to develop a variety of restoration methods for ecological restoration, and technology was at the forefront. Land reclamation is the main way of ecological restoration in mining areas. The land reclamation rate in European and American countries is more than 80%, while the land reclamation rate in Chinese mining areas is only about 20%, which is far lower than the international average level of 50%-70%. The State Council promulgated the "Regulations on Land Reclamation" in 1989, the "Regulations on Land Reclamation" in 2011, and the "Measures for the Implementation of the Regulations on Land Reclamation" in 2019. In the same year, the "Regulations on the Protection of the Geological Environment of Mines" were revised, and the State's policies, funding, governance methods and priorities for mine restoration have gradually improved and improved with the development of The Times.

1.4 Construction Difficulties

Before the mine restoration construction, a series of data such as start-up procedures, planning instructions, environmental impact reports and approvals, geological disaster assessment reports, geological exploration reports, etc., are the "blocking points" of mine treatment projects, such as tedious data preparation and approval procedures, difficult approval, and time-consuming handling. During the construction process, the local government needs to coordinate multiple relationships among departments, construction units, mining areas, and villagers. Most of the land occupied by the mining area is collective land. After construction, farmers need to deal with the issue of land transfer rent payment. Villagers are worried about the quality of land after reclamation and are unwilling to accept reclaimed land and other social problems.

2. Repair existing problems and improve measures

2.1 Repair Mechanism

The central and local governments attach great importance to the ecological restoration of mines, and have introduced more detailed systems to promote mine restoration. Local governments should strengthen the implementation of policies to maximize the enthusiasm of mining enterprises and various social resources. Local governments have rationalized the powers and obligations among departments related to mine restoration, formed a scientific and standardized system with natural resources departments as the main body and the active participation of ecological environment, forestry, water conservancy and other departments, refined the constraint and incentive mechanism, promoted coordination and communication among departments, and improved the enforcement power of ecological environment and forestry departments in the evaluation and supervision of ecological restoration quality. Improve the restoration speed and treatment rate of historical mining areas.

2.2 Restoration Funds

There is a huge demand for mine restoration funds, and the restoration funds of historical mines are more short, requiring financial allocation support, the total amount of special funds allocated by the central government is small, and the matching funds of local and enterprise are not high. As of the end of 2017, the central government had invested a total of about 30 billion yuan, and local governments and enterprises had raised a total of nearly 70 billion yuan, which could not meet the needs of large-scale mine restoration, and the funding problem had become a bottleneck restricting the ecological restoration of mines. The sources and channels of special funds for mine ecological restoration are not perfect, and mining laws and regulations give natural resources, forestry, ecological environment, water conservancy and other departments the right to collect fees related to ecological damage, and the lack of centralized management of fees has caused scattered uses and not all of them are used for mine restoration. The effect of ecological restoration is slow, the income is small, the profit method is single, and the participation of social capital is low. The Regulations on the Protection of Mine Geological Environment issued by the former Ministry of Land and Resources established a deposit system for the restoration of mine environmental governance, which is only applicable to newly built mines or mines under development, and does not include the environmental governance and ecological restoration of historical mines.

The central government will increase support for special funds for the restoration of abandoned mines left over from history, and promote the availability of matching funds from local governments and enterprises. The ecological damage fees collected by local government departments shall be centrally managed and incorporated into a unified special account for ecological restoration, and the supervision of funds shall be strengthened and earmarked for special purposes to ensure that all fees are used for mine restoration. Drawing on the successful experience of water environment (PPP) governance projects, the state encourages social capital to participate in mine ecological restoration, and supports and helps enterprises in project implementation, tax incentives, financial subsidies, etc., and implements the reward mechanism of "who repairs, who benefits". Expand the scope of application of the deposit, and use a certain proportion of funds for the restoration of abandoned mines left over from history to further meet the needs of national and local special funds for mine restoration.

2.3 Restoration Mode

The problems of mine ecological environment include landscape type destruction, environmental quality type destruction and biological type destruction. The traditional restoration model mainly focuses on landscape recurrence restoration (eliminating geological hazards and vegetation coverage), and less takes into account environmental quality restoration (controlling water, air and soil pollution) and biological restoration (restoring biological communities and species). At present, the mode of mine environmental treatment and restoration is simple, resulting in the economic and social benefits are not obvious, and the investment and return have not formed a virtuous cycle.

Adhere to the priority of ecological restoration and management, adopt the "development, governance", according to the type of mine and regional location of the ecological environment state index and the degree of damage to the surrounding environment, classified policies, regional control, hierarchical governance, step by step. On the basis of the landscape reproduction model, we should expand a variety of potential restoration models, and transition from land reclamation to a diversified development trend that takes into account the benefits of all aspects. At present, there are not many examples of mine parks, country parks and creative and cultural industry models in China, and they have not formed a scale and industrial chain, which can become the future direction of operation. Seize the opportunity of the country to vigorously implement the rural revitalization strategy, make full use of various policies to help and benefit agriculture, and repair and manage abandoned mines well while building new rural areas.

2.4 Restoration Works

In recent years, the implementation effect of the mine rehabilitation project has made obvious progress, but there are still problems such as unreasonable restoration plans and goal setting, lack of scientific and normative, low restoration standards for most management projects, low participation in funds, less acceptance standards and norms, and uneven acceptance quality.

Local governments and restoration enterprises should work out different types of mine restoration plans according to factors such as the type of mine pollution, the degree of ecological environmental damage, and human geography, with phased indicators and the completion time of the overall restoration target, and conduct strict review with high standards to avoid loopholes in the plans. Mine restoration funds are strictly managed as a whole, and their use is supervised and inspected by means of "random sampling of inspection objects in the supervision process, random selection of law enforcement inspectors, and timely disclosure of random inspection and investigation results to the public" (referred to as "double random, one public") to ensure that all funds are reasonably used in restoration projects. Revise and improve the acceptance standards of the project, hire qualified and experienced mine restoration related institutions, third-party design institutes and mine management companies to carry out the one-by-one acceptance inspection of the mine treatment plan, medium-term objectives and ecological restoration after treatment, and put forward targeted improvement plans for the problems and deficiencies found in the acceptance, so as to promote rectification through acceptance and avoid inadequate treatment measures. The phenomenon of substandard treatment projects occurs.

2.5 Repair Techniques

Mining has caused serious damage to topography and landform, and there are subsidence areas, tailings ponds and waste discharge fields covering a large area, etc. As of 2018, a total of 1.2×l04 ground collapse disasters have occurred in abandoned mines in China, and the solid waste stock is 4.96×1010t, with high construction technical requirements. Compared with water pollution and air pollution, mine restoration has less attention, less research on related technologies, and the existing technologies are relatively simple, mainly in geological environment management, secondary disaster prevention and control, vegetation restoration and land reclamation. In the "National Soil Pollution Survey Announcement" published in 2014, 1,672 soil points in 70 mining areas accounted for 33.4% of the exceeded points, and the main pollutants were cadmium, arsenic, lead and polycyclic aromatic hydrocarbons. The soil pollution control technology was weak, the plant survival rate was low, and no integrated control system was formed. In recent years, some new technologies have achieved good results, but the cost is high and the application is limited. In 2013, the Technical Code for the Protection and Restoration of the Ecological Environment in Mines (Trial) issued the development of industry standards, which did not enforce and play its due role in guiding technical requirements for the protection and restoration of the ecological environment, including waste dumps, open-pit stopes, tailings ponds, special roads for mining areas, mining industrial sites, subsidence areas, gangue yards, polluted sites, etc. The regulations on pollution prevention and control involving air, water and soil are relatively simple, and there are no more detailed technical guidelines and norms for one aspect, and no new technical norms have been issued since then.

In accordance with the differences in the types and mining methods of mines under different natural conditions, the state formulates standardized and serialized restoration standards and treatment technical norms to improve operability, enforce implementation, raise the level of mine treatment, and reduce the number of mines that do not meet the treatment standards. Strengthen the basic theoretical research of mine ecological restoration, improve the level of scientific and technological support, and reduce the application cost. At present, ecological restoration technology is mainly based on physical restoration, chemical restoration, biological restoration and joint restoration. Single restoration technology often cannot meet the needs of mine ecological restoration, and joint restoration technology will be more and more applied to mine restoration. Under the premise of ensuring the treatment of geological environment and the elimination of heavy metals and other major pollution, the mine restoration can improve the survival rate of vegetation, achieve the reconstruction of biodiversity and the restoration of regional ecological functions.