Land reclamation refers to the use of engineering, biological and other measures to rectify and restore the damaged or abandoned land in the process of production and construction, as well as the damaged or abandoned land caused by natural disasters. The objects of land reclamation in mining areas include four categories: first, digging and damaging the land, that is, the mining field of open-pit mines; Second, it covers an area, including waste rock yard, tailings pond and power plant pulverized coal ash storage; Third, the subsidence area, because the mined-out area is formed after the ore body is mined, the ground collapses or cracks appear; The fourth type is occupied land, including industrial buildings, civil buildings and roads in mines. The land reclamation planning of mining areas mentioned in this paper refers to the reclamation activities of a single mining area, which is a planning activity carried out simultaneously with mine design.
Land reclamation in China's mining areas has gone through two stages: spontaneous reclamation before the promulgation of 1989 Land Reclamation Regulations and legal reclamation afterwards. Over the years, due to the influence of planned economy, a large number of mining areas to be reclaimed have been accumulated on one side. Statistics show that about 4 million hectares (60 million mu) of wasteland have been excavated, collapsed and occupied by industrial and mining production and construction in China. In the case of tight supply of reclamation funds, more than 40 thousand hectares of industrial and mining wasteland are added every year. Although the Regulations on Land Reclamation stipulates the main body of reclamation, the principles of reclamation organization, land ownership and sources of funds, the detailed rules for implementation have not been formulated in time, and the relevant departments have different opinions on the channels of funds, distribution of benefits, reclamation standards, management and supervision. In the specific work, it is impossible to coordinate actions and there is no mechanism for reclamation according to law. Many mines have not planned the land reclamation in mining areas according to the principle of "unified planning of land reclamation with production and construction, and consideration of land reclamation requirements in process design". The planning only puts forward the land reclamation area in general, lacking formal design, let alone practical organizational measures and financial guarantee.
In recent years, the research on land reclamation technology in mining areas mainly focuses on: stabilization technology, harmless technology, greening technology, functional technology and comprehensive research on social, ecological and economic benefits. However, the management system, including the compilation of reclamation planning, the formulation of reclamation standards and the improvement of policies and regulations, still needs efforts from all sides. This paper mainly puts forward some superficial views on the general problems, principles, contents and steps of land reclamation planning in mining areas.
1 mining land use planning and land reclamation planning
In China, according to the nature and purpose of land use planning, it can be divided into three types: general land use planning, special land use planning and land use design. The special land use planning is a plan aimed at specific issues such as land development, utilization, renovation and protection under the framework of the overall land use planning, and it is a supplement and deepening of the overall land use planning, including land development planning with development as the core content, land renovation planning with renovation as the core content, land reclamation planning with reclamation as the core, land protection planning with protection as the core and land consolidation planning with consolidation as the center. According to the types of wasteland, land reclamation planning can be divided into mine development wasteland reclamation planning, coal mine subsidence land reclamation planning, transportation, water conservancy and other engineering excavation land reclamation planning, abandoned homestead reclamation planning and so on. As shown in figure 1.
Land reclamation in mining area only refers to the reclamation of abandoned land and subsidence land in mining area. There are two kinds of reclamation planning: one is the reclamation planning before resource exploitation, which adopts the combination of stripping and reclamation, while mining and reclamation, in order to achieve ideal social and economic benefits and minimum environmental impact, and realize the shortest ecological recovery cycle in the mining area; The second is the reclamation scheme of abandoned land and collapsed land left over from the past. The overall land use planning landform is relatively static and stable, the surface material composition is relatively clear, the suitability evaluation results are easy to be implemented in blocks, and the land use objectives are relatively specific. The object of land reclamation planning in mining area is a kind of artificial reconstruction landform in future space, which changes dramatically in time and space and has a certain stable period. The composition of surface materials needs to be scientifically predicted according to many factors. Land suitability evaluation is to evaluate the land types that may appear in the future space, and the land use goal consists of a series of sub-goals or stage goals.
Figure 1 Classification icon of land use planning
2 the content of land reclamation planning in mining area
Land reclamation in mining areas is a much more complicated professional and multidisciplinary system engineering, which requires the participation of professionals such as geology, mining, environmental engineering, geochemistry, soil, ecology, plants, and soil and water conservation. According to the requirements of scientific and reasonable land reclamation in mining areas, reclamation planning can not be separated from five stages of mine design, production, pit closure, reclamation and development and utilization of reclaimed land involved in mine projects.
In the stage of mine planning and design, it is necessary to investigate land dynamics, geology, soil types, surface water and groundwater, animal and plant composition, land use, tradition or other resources that need special protection. Large mining areas can be subdivided into multiple land units according to different environmental characteristics and sensitivities, so as to select the technology that can best achieve the production and reclamation goals. The stage of mine production includes the preparation of mine site, the protection of topsoil after stripping, the construction of production facilities, the mining of ore, the disposal of tailings and stripped waste rocks, etc. In order to ensure the development of reclamation work, it is necessary to ensure that the roads entering the mining area are smooth and can be expanded; Minimize the transportation distance between the placed ore and the topsoil; Avoid destroying land units in environmentally sensitive areas; The impact outside the mining area is minimal, avoiding steep soil splitting and filling or other large-scale excavation work; The noise and visual impact on nearby land users is minimal; It is convenient to implement the drainage plan of the mining area; Make the location of the mining area the most reasonable for the future use of mine land. The work related to land reclamation in the pit closure stage includes the systematic evaluation of mining area, the development and utilization planning of reclaimed land, the reconstruction of landform and ecosystem, the pit closure scheme and the possible impact assessment of reclamation activities, and the completion of surface mapping and soil covering as soon as possible, and the restoration of vegetation, surface drainage system and border land as soon as possible. The stage of reclamation and reclamation land development and utilization is mainly to monitor land maturity and ecosystem.
Land reclamation planning in mining areas involves all links from mine planning and design to mine pit closure and reclamation land development and utilization. Mine land reclamation planning should include the following four aspects: mine production planning; Land reclamation management planning; Reclaimed land development and utilization planning; Development planning of mining area after mining. These four aspects run through the mine development from the initial design stage, the mining stage to the development of the mining area after the resource is exhausted. The land reclamation planning in the mining area is closely related to the other three aspects, which ensures the coordination of economic benefits, land development and utilization benefits and ecological environment benefits in the mining production stage, provides a good natural ecological environment foundation for the natural, economic and social development of the mining area after the resource is exhausted, and enhances the sustainable development ability of the mining area.
3 principles of land reclamation planning in mining areas
Resource development has different degrees of influence on water, atmosphere, soil, animals and plants, underground resources and so on. Land reclamation in mining areas is one of the important measures to restore or make up for these effects. According to China's land supply and demand situation and foreign successful experience, the following planning principles are put forward.
(1) The principle of adjusting measures to local conditions. According to the natural and climatic conditions where the mining area is located, according to the results of land suitability evaluation, all kinds of land are reasonably arranged, so as to maximize the benefits of the destroyed land and transform potential productivity into real productivity. For example, the deep water area is transformed into a fish pond, and the non-water area is transformed into cultivated land, woodland or garden. Adapting to local conditions is not only reflected in spatial differences, but also in practice replacement. For example, paddy fields before coal mining collapse were destroyed because of underground water system, and some areas after collapse could only develop dry farming because of the discharge of surface groundwater.
(2) the principle of continuity. The idea of sustainable development is particularly important for land reclamation planning in mining areas, because the abandoned land and subsidence land in mining areas are produced precisely because of unsustainable resource development and utilization. Only the land reclamation planning based on sustainable development, sustainable utilization of land resources and improvement of ecological environment can ensure the sustainable development of social economy, change "waste" into available and realize sustainable utilization.
(3) The principle of comprehensive benefits. The goal of land reclamation in mining area is to integrate social, economic and ecological benefits into the best comprehensive benefits. Even land reclamation lies in social and economic development and maintaining the balance of ecological system, seeking the unity of social, economic and ecological benefits.
(4) the principle of unity. Adhering to the unification of mining process design and reclamation design is a common practice in foreign mines, and it is also clearly required by mining regulations. Incorporating the reclamation content into the mining plan, unified planning and management, and adjusting the mining procedure, dumping procedure and dumping technology according to the requirements of land reclamation can not only save the reclamation cost, but also restore the function of the damaged surface as soon as possible. This is also a point that must be paid attention to in China's mine planning.
4 mining land reclamation planning steps
According to the contents and principles of land reclamation planning in mining areas, it can generally be composed of the following six steps:
(1) Determine the planning scope and objectives. For the formed abandoned land and subsidence area, the planning scope should be proposed by the local government according to the surrounding physical geography and social and economic development; Production mining areas and planned mining areas are jointly determined by mining enterprises and local governments. The planning objectives are put forward by the organization that determines the scope of reclamation, and the opinions of local people are widely solicited.
(2) Collection of reclamation data. It mainly includes the data of land use, soil, hydrology, geology, population, economy and society in the planning area, which lays the foundation for the classified evaluation of reclaimed land.
(3) Classification and mapping of reclaimed land. Based on the comprehensive analysis of the natural characteristics, human needs and socio-economic conditions of the planning area, according to the planning objectives and principles, the dominant factors affecting the types of reclaimed land use are selected as classification indicators, and the reclaimed land is classified and mapped as the basis for the suitability evaluation of reclaimed land.
(4) Evaluation of reclaimed land. On the basis of classified mapping of reclaimed land, all kinds of land are evaluated.
(5) Planning and design of reclaimed land. According to the above evaluation results and the requirements of planning principles, the rational utilization model of reclaimed land is constructed.
(6) Implementation and adjustment of reclaimed land planning. The implementation of land reclamation planning in mining area is accompanied by the gradual advancement of mining, and the adjustment of reclamation plan is carried out simultaneously with the implementation of mining plan. In order to ensure the smooth implementation of reclamation planning, a set of detailed measures should be formulated to promote the full implementation of the planning scheme.