I. Status of China's tailings resources
The tailings problem is ubiquitous on an international scale. According to the statistics of relevant departments in China, there are 12,718 tailings ponds in China, of which 1,526 are tailings ponds under construction, accounting for 12% of the total, and 1024 tailings ponds have been closed, accounting for 8% of the total. The total amount of tailings in the country is 8.046 billion tons, and it is increased by 300 million tons per year. According to other data, there are dozens of tailings with major catastrophes in the country's tailings. The massive accumulation of tailings brings many problems such as resources, environment, safety and land.
At the same time, because 80% of China's mineral resources are associated mines, and China's mining industry started late, the technology development is not balanced, and the technology of metallurgical technology in different periods is very different. Therefore, a large number of valuable resources remain in the tailings. For example, iron ore tailings of China's total iron grade average of 8% to 12%, some even up to 27%. Based on the current total iron tailings stock of 4.5 billion tons, the tailings are equivalent to about 500 million tons of iron. In areas where mineral resources and tailings are concentrated, tailings are rich in resources. There are 61 tailings reservoirs in the tin polymetallic deposit in Nandan, Guangxi. In the total tailings of 25.22 million tons, there are a large number of non-ferrous metals such as tin, antimony , lead , zinc , silver , gold, indium , cadmium and non-metallic minerals. Arsenic , sulfur, etc., grades are above the national industrial grade indicators, and some have reached large or extra large scale, initially estimated to have a resource of 3 billion yuan. If we rely on the new development of mineral processing technology , the recovery of these metals is no less than the establishment of a new mine. For example, the tailings of the Panzhihua Iron Mine in Sichuan contain more than ten beneficial components such as copper , nickel , titanium and vanadium , which is equivalent to a large non-ferrous metal mine. The non-metallic minerals such as coal gangue and other surrounding rock mines, etc. are also useful material, but it has been mined to the ground, easy to carry out further sorting. In addition, the Nanling area in the south, Chenzhou in Hunan, Shaoguan in Guangdong, Yulin Baise in Guangxi, Sanjiangyuan in Yunnan, and many areas in the Northeast are all non-ferrous metal metallogenic belts. Some tailings ponds rich in metal deposits have even caused buying interest in developed countries such as Japan.
It can be seen that tailings are not completely useless waste and often contain components that can be used for other purposes. With the development of production technology, these useful target components in tailings may also be further recycled. The value of these discarded “garbage†is huge, and it is tantamount to a treasure trove of mineral resources.
The comprehensive utilization of tailings is of great significance to China. On the one hand, China is in the stage of accelerating industrialization and urbanization. The consumption of mineral resources is large and the dependence on foreign countries is high. The utilization of tailings can alleviate the shortage of resources in China. On the other hand, China is a large mining country, developing and utilizing a large number of long-term accumulated tailings, which can not only turn waste into treasure, but also effectively alleviate the environmental pressure brought about by resource accumulation. It can be seen that there is a business opportunity for secondary utilization in the tailings. Therefore, experts believe that the current task of China's mining circular economy is to develop and utilize a large number of tailings that have been put on hold for a long time. The realization of no waste discharge in the mineral processing operation is the need to fully utilize the mineral resources and protect the ecological environment.
Second, the development and utilization of tailings
The content of the main useful components in the mine is called the tailings grade. It is an important parameter for selecting an economical and rational beneficiation scheme and evaluating the selectivity of ore. Therefore, the development and utilization of tailings must first be geologically evaluated. It is necessary to clarify the material composition of tailings in each tailings pond, the content of useful components, the distribution in the dam (space location), the scale of various possible mineral raw materials, the possibility of geological disasters and their prevention. Evaluation, etc. Therefore, the development and utilization of tailings should pay attention to the following two problems, namely, the need for safe production on the one hand, and the elimination of the harm caused by the tailings pond. On the other hand, the tailings are redeveloped as secondary resources to extract the remaining valuable metals. Through reasonable planning and design, restore cultivated land and beautify the environment. In comprehensive utilization, there are two kinds of valuable components for tailings recovery and comprehensive utilization of tailings.
From the point of view of the composition of the tailings, the tailings are roughly divided into four parts: First, the tailings contain the currently extractable useful components and will be utilized in the near future, which is the resource of choice for the merchants. Secondly, it is a component with important industrial value. The current technology has not yet passed the customs or the technical clearance, and the cost is very high. It cannot be put into the market for the time being. For example, tailings containing rare or rare earth elements should be properly preserved, for example, The tailings of the iron ore mine and the ore surrounding rock with rare earth elements are simultaneously produced with the ore. Third, most of the main tailings are silicate mineral raw materials. The possible directions of utilization are mainly used as building materials and land reclamation, as well as backfilling mine production tunnels. The scale of their utilization is related to the degree of local economic development. The content of heavy metals such as arsenic, mercury , chromium and cadmium in tailings used for land reclamation shall not exceed the standard; the content of radioactive materials in tailings used for building materials shall not exceed the standard; the tailings of backfill mine production tunnels shall not become polluted groundwater and surface. Source of pollution of water and soil (water associated with pollution). Fourth, there may be a small part that cannot be re-refined with useful components (very low content or problem of state), and contains high radioactive materials, which cannot be used as building materials, reclamation tailings (such as from radioactive mines and rare earths). The tailings of mines such as elements can only be treated with special sealing measures.
The valuable component of tailings recovery refers to the first consideration of the recovery of valuable metals and minerals from tailings in tailings utilization. For example, Jinchuan Nickel Mine further recovers nickel from tailings, increasing the nickel recovery rate from about 50% to 90%. Anqing Copper Mine recovers iron and copper from tailings. It can obtain about 6.94 tons of copper concentrate with a grade of 16.94% and 53.5 tons of iron concentrate with a grade of 43%. The annual output value is 4.915 million yuan. Xinjiang Keketuohai 87 concentrator tailings comprehensive recovery from white mica, and annual output value of 8 million yuan, profits and taxes 2.73 million yuan.
The comprehensive utilization of the tailings is the direct use of the tailings without the recovery of valuable components. Generally, the physicochemical properties and mineral composition of the tailings are basically consistent with the utilization route, and the toxic and harmful components are lower than the standard, that is, the tailings can be It is developed and utilized as a composite mineral raw material. For example, some tailings can be used as the main raw material of ceramics. The firing temperature is 50-100 degrees Celsius lower than that of traditional pure materials, and energy saving is 20%. The tailings can be used as raw materials for building materials, which can save nearly half of the energy compared with conventional raw materials. Combining the relevant processes and equipment, it is possible to develop new products with new properties, such as glass-ceramics produced with gold tailings, whose performance is equivalent to high-grade glass-ceramics with gold added.
In the past, we often used tailings to recover valuable components. Although the benefits were considerable, we could not solve the problem of small tails and tails. The comprehensive utilization of tailings can be the most promising from the perspective of tailings reduction, harmlessness and resource utilization. At present, the comprehensive utilization of tailings components is mainly to prepare building materials, mine filling, soil improvement, land reclamation and so on. In addition, some tailings without great economic value or tailings with no economic value after secondary recovery can also be used as underground filling or filling paving, which can reclaim land, green afforest, or build ecology of tailings pond. Parks, sports and entertainment venues.
Third, tailings development and utilization recommendations
The development and utilization of tailings is a worldwide problem. The utilization of tailings ponds involves many disciplines such as geology and resources, mining engineering, environmental protection, landscape aesthetics, biological ecology, and metal toxicity toxicology. Therefore, to some extent, the development and utilization of tailings ponds is more difficult than the development and utilization of mines, and the requirements for safety and environmental protection are also more stringent. However, at present, China's tailings management is chaotic, the ownership is unclear, and the development and utilization lacks overall planning. Therefore, if China wants to do a good job in the development and utilization of tailings resources, it needs the support of policies, funds, and technology. It also requires the active cooperation of relevant departments and enterprises.
In order to further improve the development and utilization of tailings resources, the following measures are recommended:
1. Policy aspects
From the design of the tailings pond to its comprehensive development and utilization, it is inseparable from the supervision of the safety supervision department, the environmental protection department and the land and resources department. Legislation involving the comprehensive utilization of tailings ponds should also be linked by various departments. If the regulations for the comprehensive development and utilization of tailings are established, the responsibilities of each department can be included in detail, and each department will perform its duties, which will contribute to the comprehensive utilization of tailings.
Qiao Fansheng, chief engineer of the Green Mining Office of China Mining Association, pointed out that for the comprehensive development and utilization of tailings, there must be a unified regulation or regulation, and the management and use rights of the tailings pond should be clarified. At the bottom of the mine, they are classified into different categories and a unified plan is drawn up. Through unified management and unified planning, different types of tailings are deployed and used in batches according to their performance differences and their different needs, rather than rushing. In addition, the plan should adhere to the principle of science, such as adhering to the principle of short-term development of tailings development, first easy and then difficult.
In the specific implementation, we should pay attention to the following three points. First, we must formulate and implement relevant policies to support enterprises in carrying out technological research and technological transformation. At the same time, we must implement preferential policies such as reducing and exempting resources, taxes, and fees, and guide and encourage social and enterprise funds to invest in tailings and other resources. . The second is to use the central financial funds to focus on supporting the utilization of resources in large enterprises, tailings and “waste†in large mining areas, and to play a guiding role. The third is to strengthen the development of access management, formulate and improve the standards for the access and supervision of mining development enterprises, promote the restructuring of enterprises, and strengthen and expand mining enterprises.
2. Technical aspects
China's work on technology guidance has been done relatively well. During the “Twelfth Five-Year Plan†period, in order to improve the comprehensive utilization level of mineral resources, China will promote the comprehensive development and efficient utilization of the associated mineral resources, and improve the comprehensive utilization capacity and level of the associated resources of oil , coal and other energy minerals, focusing on black. The multi-use, cascade utilization and high-value utilization of the associated resources of colored, precious metals and rare rare earth metal minerals, and the deep processing and comprehensive utilization of associated resources of non-metallic minerals. Improve the level of waste of resources, focusing on emissions from large, stockpiling large, polluting the bulk solid waste utilization and high value-added utilization, continue to promote fly ash, coal gangue, tailings, desulfurization gypsum, phosphogypsum, smelting Waste materials such as waste residue and construction waste are utilized.
However, the research and development capabilities of tailings utilization in China are still weak, and the tailings are extensively utilized. The main reason is that China's development and utilization of tailings and research work are concentrated in various mining enterprises, and there is no unified management and coordination organization. Each mining company has its own battles. Due to the limitations of capital and research and development capabilities, the research and development of tailings tends to be at a relatively low level. For some difficult research projects, no matter from the capital aspect or the configuration of scientific research personnel, it is impossible to form a joint research, and some utilization methods are relatively extensive, and it is impossible to develop useful components in the tailings.
In the future, in terms of technology, it is necessary to strengthen the technological innovation of comprehensive utilization of tailings, research and develop advanced technology, advanced equipment, advanced technology, and accelerate the transformation of research results.
Fourth, the conclusion
According to the China Mining Association's tailings comprehensive management office, the potential value of China's tailings is about 130 billion yuan, and the economic benefits brought about by its development and utilization are extremely attractive. However, there are still many problems related to the recycling of tailings, which need to be studied in depth. It is recommended that relevant departments do a good job in the investigation of tailings and the market in the early stage, find out the tailings, and provide scientific basis for tailings utilization and decision-making from the data to avoid decision-making. The blindness causes waste of resources. Technically, China should increase the research on the full-use utilization technology of tailings, develop high value-added building products, and realize the process of small tail and no tailing. In the future, China needs to change its concept, innovate technology, and realize the reduction, resource and benefit of tailings, thus accelerating the construction of a resource-saving and environment-friendly society.
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