Five major regional mine environmental geological problems

The first chapter is the regional distribution characteristics of environmental geological problems in mines in China

China is the world's third largest mining country, its mineral resources account for about 14.6% of the world's mineral resources, mining 193 kinds of minerals. Mineral resources play an important basic role in China's social and economic development, about 95% of the primary energy and more than 80% of industrial raw materials, most of the agricultural production means and 1/3 of the drinking water are from mineral resources. While constantly developing mineral resources to meet the needs of daily life, people have caused many environmental geological problems because of the unreasonable frequent exploitation of mineral resources, which has changed and destroyed the natural environment around the mining area.

1. Regional distribution profiles of different geological environments

Mine environmental geological problems are greatly affected by regional geological environment conditions, and the types of environmental geological problems caused by mining in different geological environment regions are very different. For example, mining in mountainous areas is prone to collapse, landslide, debris flow and other disasters, while mining in plain basin areas will aggravate the destruction of vegetation and the occurrence of ground collapse.

China's geological environment conditions are complex and diverse. According to the factors of China's landform, meteorology and hydrology, vegetation, geotechnical properties and primary environmental geological problems, the geological environment background affecting the distribution of environmental geological problems in China's mines can be divided into six major geological environment regions. In terms of different geological environment regions, the occurrence times of mine geological disasters from high to low are middle-high mountain region, middle-low hill region, plain basin region, loess plateau region, Gobi desert region and permafrost region. Among them, Sichuan, West, Yunnan, Guizhou, Hubei, Hunan, Guangxi and other regions are intermixed with mountains and rivers, with many valleys, and the climate is wet and rainy. The development of debris flow, landslide and collapse is more serious. The number and types of geological disasters caused by different types of mining are also different, among which the coal mine problem is more serious than the metal mine, the metal mine problem is more serious than the non-metal mine.

2. Mine environmental geological problems in different geological environment regions

2.1 Middle and high mountain areas

The middle and high mountain areas are rich in minerals, mainly developed minerals are coal, metal minerals such as gold, lead zinc ore, iron, copper, manganese, tin and non-metallic minerals, and its mining development degree is strong. However, because the region is located in the high mountainous area, the main disaster types of mining are debris flow, landslide, collapse and so on. Secondly, the mining of metal mines and coal mines can easily lead to water and soil environmental pollution, vegetation destruction, land occupation and ground collapse. 

2.2 Middle and low hilly areas

The middle and low mountain and hilly areas have good natural ecological environment, dense population, fast economic development and high mining development intensity. Mainly mining coal, iron, gold, tungsten tin ore, rare earth ore and non-metallic building materials and other minerals, and coal mining and metal mining is the main problem of environmental geological damage. The main problems in coal mines are: Ground collapse, ground cracks and drainage pollution, etc. Its prominent mining areas are mainly distributed in Hegang of Heilongjiang Province, Fuxin of Liaoning Province, Yuanbaoshan Coal mine area of Chifeng, Inner Mongolia → Tai 'an Coal mine area of Taishan and Jiaodong Peninsula, Laiwu coal and iron mine area, Zibo coal and iron mine area, Loudi City in Hunan Province, Lengshuijiang City in Hunan Province, Yizhan County Yangmeishan coal mine area → Guangxi Heshan coal mine area in southern Guangxi Province, etc.

The most prominent problems in metal mining are the pollution of water and soil caused by acid wastewater and heavy metals. The second is land occupation and debris flow, collapse, landslide. It is mainly distributed in Chenzhou Shizhuyuan non-ferrous metal mining area, Yizhang County Yaogangxian tungsten ore area, Manaoshan iron manganese ore area, Ganzhou Dexing copper cope-Jinshan gold mining area, Gannan Chunyuyu tungsten ore development zone and Jiaodong Peninsula gold mining area.

The distribution area of non-metallic mines is mainly in Zhejiang and other places, and the province mainly mines building materials such as brick clay, sand and limestone for construction. Among them, land occupation and destruction and ground collapse are the main environmental geological problems in this region. The number of subsidence and the area of subsidence area account for 83% and 75% of the total number of subsidence mines, respectively. Jinhua fluorite mining area in Zhejiang Province is one of the most serious areas of ground collapse.

2.3 Plain basin area

The environmental geological problems caused by coal, phosphorus, iron and construction sand mining in this area are more serious, and the ground collapse caused by coal mining is the most prominent problem. The second is the death of the people caused by the fall of the groundwater level, the debris flow and the collapse caused by the occupation and destruction of the land and the drainage of the mine. Coal mining subsidence in Xuzhou, Jiangsu province has developed into a national typical, and the ground subsidence area accounts for more than 98% of the total subsidence area in the province, and the subsidence continues to expand. The coal mining areas with serious problems are mainly located in Baolixile coal mine area in Inner Mongolia, Jalainur Coal Mine area, Tieling Tiaobingshan Coal mine area in Inner Mongolia, Yinchuan and Hetao Plain area in Wuhai Coal mine area in Inner Mongolia, Shizuishan Coal mine area in Ningxia, Tangshan Kailuan Coal Mine in North China and the middle and lower reaches of Yangtze River Plain area, and Yima Coal Mine in Henan Province Mine, Shandong Jining - Zaozhuang Coal mine, Anhui Lianghuai Coal mine, Jiangsu Xuzhou coal mine, Hunan Loudi Coal mine, Changsha Ningxiang Coal mine and other mining areas.

2.4 Loess Plateau area

The ecological environment in this area is fragile, so the mineral exploitation intensity is medium, and the main environmental geological problems in this area are coal mines and metal mines. Weibei Coal mine area in Shaanxi province is a serious mining area that has damaged the environment. In Tongchuan Coal mine area in Shaanxi Province, the groundwater level of the mining area has decreased due to the influence of coal mining. The metal mines are mainly Baiyin copper mining area and Lashuixia copper-nickel mining area, which contain a large amount of heavy metal acid water in the wastewater of the mine area, and its discharge is large, which causes great pollution to the surrounding environment.

2.5 Gobi Desert region and permafrost region

The sand area and permafrost area of the Gobi desert belong to the fragile ecological environment, the natural environment conditions are poor, and the development intensity of the mining area is low, so the mining in this zone mainly focuses on the protection of the ecological environment.

The second chapter is the mode of mine environmental restoration and management

After mineral resources are extracted from underground, the most direct impact on geological environment is to change the original ground stress. All kinds of underground mining areas are widely developed mining subsidence problems, such as subsidence basin, collapse pit, ground cracks and other surface rock and soil body failure phenomena. As of 2015, the total subsidence problem area caused by resource mining in Inner Mongolia Autonomous Region is about 306.37km2, which is concentrated in underground mining coal, ferrous metal, non-ferrous metal and precious metal mining areas, among which the subsidence problem area caused by coal mining is about 305.77km2, accounting for about 99.80% of the total problem area.

1. Definition and analysis of mine environmental restoration and management mode

Mine environmental restoration and governance model takes mine geological environment restoration and governance as the main research object. As can be seen from the definition of mine environmental restoration model, the key contents of the model are shown in Figure 1, including: mine environmental geological problems, mine environmental restoration objectives, mine geological environment background, mine development and utilization conditions and mine geological environment restoration and governance model. As can be seen from Figure 1, mine environmental restoration and treatment is a systematic study of mine geological environment, mine environmental geological problems and mine restoration and treatment technologies. Mine environmental restoration and governance mode is an organic and systematic combination of mine environmental restoration technologies, but the technical composition of restricting and guiding mine environmental restoration and governance mode is closely related to the other four aspects. As shown in Figure 1, the five research contents of mine environmental restoration and governance modes, including mine geological environment background, mine development and utilization conditions, and mine environmental restoration objectives, are correlated with each other. The author divides the correlation into the outer "progressive" relationship and the inner "five elements" relationship.

The contents of the outer "progressive" relationship have progressive research correlation with each other, and this "progressive" relationship is helpful to promote the study of the model of mine environmental restoration and governance. Various contents in the internal "five elements" relationship establish internal multi-directional correlation through the mine environmental restoration data model, and become the research content of the technical composition of the guiding model, the application scope of the restoration model, the verification of the model benefit, and the optimization and improvement of the model. Therefore, the five contents also have the characteristics of "two-way" correlation.

2. Macro construction of mine environmental restoration and governance model

The mode of mine environmental restoration and management is a tool to prevent and solve the contradiction between mine environment and problem restoration. Based on the conditions of mine development and utilization and the geological environment background of mine, it is necessary to grasp the law of problem occurrence and put forward preventive measures on the one hand, and repair and control the existing mine environmental problems on the other hand. Therefore, the model is based on the practice of mine environmental restoration to carry out theoretical research, with both typical mine environmental restoration project cases as the technical research background and specialized research on restoration technology, combining the mine environmental restoration experience in different regions of China with the mine restoration theory. A set of mine environmental restoration model with reasonable technical composition, suitable for mines in different areas and complete system has been formed.

The primary task of mine environmental restoration and management model research is to deeply understand the mine environmental problems. Domestic scholars have many classification schemes for mine environmental problems, such as classification based on mine development stage, classification based on mineral species, classification based on the manifestation and impact results of mine environmental geological problems, and classification based on the characteristics of mine environmental geological problems. In the study of model objects, the author focuses on the comprehensive classification scheme of problem nature, and divides common mine environmental problems into: Ground collapse problem, solid waste problem, liquid waste problem, open-pit slope stability problem, water layer structure damage problem and mine secondary geological disaster problem.

According to the functional requirements of the model, the author divides it into three functional sub-modules: engineering disaster elimination module, ecological restoration module and biological restoration module. The functional module of mine environmental restoration and governance mode is shown in Figure 2, in which the main function of the engineering disaster elimination module is to eliminate or prevent regional disaster hazards. The technical types of the module include disaster elimination and restoration technology and engineering restoration technology, which are mainly used to strengthen and transform surface rock and soil bodies and prevent unsafe hazards such as rock and soil bodies and geological bodies. The main function of the two sub-modules, ecological restoration module and biological restoration module, is to promote the restoration of rock and soil mass and ecological environment, and use ecological restoration technology and biological restoration technology to cooperate with the engineering disaster elimination module to complete the mine environmental restoration, so as to achieve the land restoration and ecological restoration goals of the model.

According to the decomposition of mode function modules, the author sets the code for the engineering disaster elimination module, ecological restoration module and biological restoration module in the order of constituting technologies as follows: Disaster elimination and restoration technology (Ai ~ Di), ecological restoration technology (Ei), biological restoration technology (Bei), the code is conducive to the systematic description of the composition of the model, and the macro construction of the mine environmental restoration management model such as "Ai+Bi+Ci+Di+Ei+Bei" and other organic construction of mine environmental restoration technology.

3. Establishment process of mine environmental restoration and management model

The establishment process of mine environmental restoration and governance model is shown in Figure 3. "Restoration of mine environmental problems" is the first step, which goes through the study of technology and objectives, and constitutes the establishment process of the model in a clockwise cycle. In this process, the restoration and governance technology and problems, and the restoration and governance objectives and problems have mutually feeding effects of benefit feedback, and each step has different influence characteristics on the model.

The restoration of mine environmental problems, namely: the understanding of the restoration object, mainly includes the investigation of mine geological environment, the assessment of geological environmental problems, and the typical treatment project cases. Mine environmental investigation refers to five aspects: mine geological environment investigation, mine water environment investigation, mine ecological environment investigation, mine atmospheric environment investigation and mine space environment investigation. This paper focuses on the geological environment survey of mines, and provides basic data on the scale, characteristics, background and occurrence rules of environmental geological problems to illustrate the establishment process of the model. Mine geological environment assessment is a quantitative and qualitative evaluation carried out on the basis of field investigation. It takes into account the complexity of geological environment background and the degree of restoration of mine environmental problems, weighs a number of mine environmental indicators, and evaluates the harm degree of problems and the impact of mining activities on the environment. Therefore, it plays a guiding role in the application scope and application objects of the restoration model. The collection of mine environmental restoration cases is the basis of the extraction and sublimation model, which is helpful to discuss the benefits and effects of the model. There are great differences in the remediation methods for similar mine environmental problems in different regions. Therefore, the remediation and governance cases become the best test method for the pertinence and universality of the remediation and governance model.

Restoration technology research is subject to the joint constraints of restoration project cases and restoration objectives. Reasonable restoration technology can come from either restoration and governance project cases or local governance experience, and an organic model is formed after being determined and coded according to module functions. Therefore, the model is the optimization and organic combination of restoration and treatment technologies, and the characteristics of the technology restrict a number of characteristics of the model, such as: the applicable conditions of the model, the key technologies of the model, the expected results of the model, etc., which has a great impact on the learning, understanding and promotion of the model by mine users. In addition, the expected benefit of remediation technology, construction technology, economic cost and other aspects restrict the application of remediation model.

The objective of mine environmental restoration is the expected benefits and results of mine environmental restoration proposed on the basis of the understanding of the restoration image and the restoration experience of mine environmental problems and the existing restoration technology. It has a guiding effect on the construction of the model and becomes the basis for judging the rationality of the application scope of the model. Mine environmental restoration goals are divided into geological engineering goals, land restoration goals and ecological restoration goals, which must conform to the government policy, laws and regulations and the actual situation of the mine environment. Mine environmental restoration goals can lead to the establishment of targeted restoration models, and mine environmental restoration governance models can be classified according to different restoration goals.

4. Characteristics of mine environmental restoration and management mode

4.1 Pertinence

 The model study focuses on restoration object, restoration target, restoration technology and other contents, and each content focuses on targeted research. Specifically, the application scope of the restoration mode related to mining subsidence problem takes into account the different performance characteristics of the surface of the problem, such as subsidence basin, collapse pit, collapse trough and ground fracture, etc. The engineering restoration technology of different occurrence forms must correspond to different targeted technologies in order to achieve the benefits of the restoration mode.

4.2 Universality

Mine environmental restoration and management model is a set of systematic and perfect mine environmental restoration theory, which involves many mine environmental geological problems. In other words, the model is applicable to the mines or regions where the vast majority of mine environmental problems occur. Universality means that under the constraints of the scope of application of the mine environmental restoration and treatment model, the model can be used in the mine environmental restoration and treatment project with similar problems. For example, in Shanxi, Shaanxi, Ningxia and other coal mining areas in the Loess Plateau mine secondary geological disaster control project, the hidden landslide in the mining area can be used according to the characteristics of loess landslide, the scope of application for the loess region of the mine secondary geological disaster restoration and management model, and in the model description with similar regional engineering cases to guide the preparation of treatment plans.

4.3 Procedural

Mine environmental restoration and management model can be directly applied to mine environmental restoration projects. According to the scope of application agreed by the model, it is necessary to clearly point out the characteristics of the model's composition technology, key technology and main process, analyze the engineering benefits that can be realized by the model according to existing engineering cases, and ensure that the model is simple and practical. In order to facilitate the government units, mine management departments to promote the mine environment management and prevention work. Therefore, the pattern is process-oriented, and the realization of its benefits benefits from the user's correct grasp of the characteristics of the pattern and the accurate implementation of the repair and governance technology of the constitutive pattern.

5. Optimization of mine environmental restoration and management mode

The model of mine environmental restoration and management is the study of the complex system of mine environment, which is constantly updated and optimized. The optimization of the model is closely related to the response of mine geological environment, the benefit of mine environmental restoration, the objective of mine environmental restoration and the technology of mine environmental restoration.

The model of mine geological environment response can be optimized, because the model must be established on the basis of mine environmental problems and development background. According to the characteristics of geological environment response to different mine environmental problems under many influencing factors, the type and number of problems involved in the mine environmental restoration and governance model can be expanded. In addition, due to the continuous progress and update of mine environmental restoration targets due to national policies, the model should optimize and update the technical composition to achieve new targets as the degree of target requirements changes. The benefit demand of mine environmental restoration is related to the expected effect of the model, which needs to be established on the basis of statistical data such as cost, time and area, which requires the optimization of the key technology and process flow of the model, and the continuous optimization of the model to meet the benefit demand. Finally, with the continuous progress and improvement of mine environmental restoration and management technology with the difficulty of restoration, demand and patent renewal, the model needs to be upgraded and updated to achieve the optimization of model level and benefits.