I. Introduction
With the advancement of China's industrialization construction, the demand for resources will continue to increase substantially, and the contradiction between supply and demand of resources will become increasingly prominent. Therefore, building a conservation-oriented society and developing a circular economy are in a more prominent and important position. We must further transform the economic growth mode, and promote the sustainable development of the economy and society with efficient and recycling of resources. Lu metallurgical Mining Group Company to the basic principles of mining circular economy as a guide, a useful exploration and attempt to theoretical and practical aspects of the mining cycle of economic development, and achieved results.
Second, the basic concept of mining circular economy
As the basis of circular economy, mining circular economy refers to the minerals and mineral products on the earth following the characteristics of minerals and natural ecological laws. According to their exploration, mining, metallurgy production, deep processing, consumption and other processes, the closed-loop material flow is dependent on it. The energy flow and information flow are superimposed internally to achieve an economic system that is harmoniously developed with the ecological environment and social progress, and its core is the comprehensive utilization of mineral resources.
Main modes of mining circular economy: 1) Single mining enterprise or mining group type: Internal circulation in the enterprise is the basic expression form of circular economy at the micro level; 2) Mining ecological park mode: it is an industrial symbiosis combination with mining as the skeleton 3) The social circulation model: The mining cycle system, as part of the overall social cycle, is integrated with other sub-cycles to improve the efficiency of the use of mineral resources and reduce the externalities of mining production.
The mining circular economy operates in accordance with the green economy model of natural ecological material recycling, requiring resources to follow the principles of 3R (Reduce, Reuse, Reuse, Recycle). The principle of reduction is aimed at the input, which aims to reduce the flow of material and energy into the cycle; the principle of reuse is a procedural method, with the aim of prolonging the duration of the flow of material in each process and reducing the rate of material flow; The principle of output is the method of output, which turns waste into resources again to reduce the final treatment, that is, the recycling and comprehensive utilization of waste.
Third, the practice of developing circular economy in Luzhong Mining Company
(1) Adhere to scientific and technological progress and achieve resource utilization reduction
1, iron ore Xiaoguanzhuang sheet ore recovery
The mine's geological reserves are B, C + D grades of 87,071,100 tons. According to the previous classification criteria, the off-balance mines (20% ≤ TFe < 30%) are 3,565,800 tons, with an average grade of 25.34%, totaling 90,527,900 tons. As of the end of 2006, the amount of geological minerals mined has reached 3649.80 million tons. The off-balance mine has not been considered as a mineral, and it has been basically discarded. With the shortage of iron ore resources and the improvement of mineral processing technology , iron ore previously classified as off-balance sheet ore has become a useful resource.
In 2007, the implementation of Xiaokanzhuang Iron Mine-400 m middle section northern area off-surface mine 476,800 tons of mining projects, according to the conditions of occurrence of the table, the table can be simultaneously mined, reasonable connection, make full use of the existing wells Engineering and other facilities to ensure safe production of mines. The mining is carried out from top to bottom and segmented by section, from the upper plate to the lower plate, from the two wings to the middle and backward mining, and the sub-column sublevel caving method is adopted for mining. The newly added fixed assets investment of the project is 8.336 million yuan, and the annual recovery of 90,000 tons of raw ore. The optional concentrate is 2,280,000 tons and the grade is 64%. It not only makes full use of the mineral resources, but also brings considerable economic benefits to the enterprise.
2. Re-extraction of residual ore bodies in Zhangjiatun Iron Mine
The mine is one of the main production mines of Luzhong Metallurgical Mining Company. The remaining ore deposits are concentrated in the branch ore body, and the shape and occurrence of the branch ore body are complex and variable, the ore is weak and broken, and the stopway approach is The deformation of the joint lane is serious and the mining is difficult.
Since 2002, Zhangjiayu Iron Mine has been involved in many aspects such as on-site macro investigation, support method field test, roadway displacement monitoring, residual ore body mining simulation, ore mining simulation, mining technology and roadway support decision theory. Effectively recovering residual ore bodies and improving resource utilization have been studied to strengthen the mining of branch ore bodies and to re-mining the ore that failed to recover normally.
Among them, the ground pressure control and roadway maintenance are the most important and the most urgent technical problems to successfully realize the mining of this section and the recovery of the upper part of the ore body. Through experiments, theoretical analysis, etc., the strong road pressure of mining roadway is manifested, the success rate of support is improved, and the ore recovery rate of branch ore body and upper left ore body is greatly improved. After the implementation of the project, the annual output will increase by 150,000 tons of ore, and the profit after tax will increase by 709.23 million yuan per year. It has achieved good economic and social benefits.
(2) Applying new processes to realize waste recycling
1, the transformation of iron ore dressing plant to improve recovery
The ore processing plant processed raw ore from three mining areas. In order to maximize the iron recovery rate and reduce the loss of weak magnetic minerals, Luzhong Metallurgical Mining Group Co., Ltd. decided to carry out technical transformation of the ore dressing, using fine screen re-grinding-strong magnetic-flotation- grinding - magnetic - reselection process to replace the original magnetic reselection operation, not only the weak magnetic iron minerals to obtain a better recovery, and the copper minerals are effectively enriched while increasing shaker apparatus, so that the ore grade Further improve.
Through the transformation of the project, the ore dressing index has been greatly improved. The tailings grade has been reduced from 14.5% to 11.79%, and the recovery rate has increased from 76% to 80%, equivalent to 437,000 tons of iron concentrate per year. Meanwhile, the iron concentrate grade is 63% increased to 65%, and the economic benefits are significant.
2. Technical transformation of copper and diamond concentrates for iron ore tailings recovery
The ores of the three mining areas contain associated elements such as copper and diamond. Although the copper minerals are low in content, they are present in the natural copper state and are enriched after iron selection. Therefore, copper minerals can be recovered; In the presence of oxidized and sulphurized drills, oxidized drills are currently difficult to recycle, but sulphide drills can be recycled. In order to comprehensively recover copper and drill minerals and recover associated elements, the process of recovering weak magnetic iron for strong iron tail-copper, drill-mixing float-copper, drill separation-re-election is adopted for iron ore tailings. Copper minerals have a certain magnetic property due to the surface being contaminated by magnetic minerals, and are better recovered with strong magnetic energy. The existing flotation system is modified because the copper recovery effect is poor, especially the coarse-grained copper mineral is not easy to float, mostly at the bottom of the flotation tank, together with the iron mineral as the bottom product. In the past two years, the recovery rate of copper flotation has only been about 75%. The CHF-3.5 external flushing flotation machine used in the transformation was changed to the CLF-8 coarse particle flotation machine, and the copper and drill mixing-copper and drill separation processes were used to improve the copper concentrate grade and recovery rate.
After the transformation, according to the annual processing of 2.3 million tons of raw ore in the concentrator, the copper concentrate grade can be increased to 20%, the recovery rate is increased by 13.5%; the drill concentrate grade is 0.38%, the recovery rate is 53.54%; the grade can be increased by 20% per year. The copper concentrate is 800 t and the drill concentrate is 5.07 t.
(3) Realizing the reuse of “three wastesâ€
1. Comprehensive utilization of mine wastewater
(1) Water in the well
Underground water rushing generally contains a large amount of suspended solids and metal ions. If it directly discharges polluted environment and farmland, it also seriously pollutes groundwater and surface water, resulting in economically incalculable losses. Lu Mining Group brings all levels of underground water into the large water tank of -400. After purification and sedimentation, part of it is used for underground domestic water; part of it is pumped to each working point for wet operation to reduce dust; the other part is pumped to the surface. The concentrator is in a pool of φ53 m. The downhole water contains a large amount of SO 4 2 - and Ca 2 - , Mg 2 - , and is weakly alkaline (about pH 8.3), which is just suitable for the water of the beneficiation process. In addition to meeting the underground operation water, the underground water is used for beneficiation. 'The new water consumption of the ore dressing can be reduced to 0.4 t/t ore . The annual water conservation is nearly 1 million tons and the cost is more than 1.5 million yuan.
(2) Reuse of water
After the tailings wastewater is purified and treated, it can be reused and reused, which can solve the problem of reducing the power consumption of the water source and solving the pollution problem to the environment. There are two main ways to reuse water:
- Concentrated pool backwater recycling. Because the concentration of tailings discharged from the ore dressing plant is generally low, in order to save new water consumption, the tailwater dewatering facilities such as tailings concentration tank or inclined plate concentration tank are constructed to dewater the tailings. The tailings sand is deposited at the bottom of the concentration tank, and the clarified water is pooled. It overflows and is sent back to the concentrator for reuse. The return water rate of the concentration tank is generally 40% to 70%. On the one hand, a large amount of return water can be obtained from the concentration tank to reduce the burden of the water supply source; on the other hand, due to the increase of tailings concentration and the reduction of the amount of pulp, Reduce the cost of tailings transportation.
- The tailings pond is reused. The backwater from the tailings pond is used to recycle the clarified water for use in the concentrator, which not only avoids environmental pollution, but also saves resources and achieves emission reduction or even non-discharge. After comprehensive utilization of wastewater from Lu Mine Group, it will achieve zero emissions, saving 2.49 million tons of water per year and exempting sewage charges by 1.23 million yuan; the ore recovery rate will increase by 0.28% and the sales income will increase by more than 2.8 million yuan.
2. Waste ore is used for damming and paving
The waste ore of Lu Mining Group contains a large number of red slate , which is easily weathered and muddy, which is very suitable for the construction of tailings dam; after mixing with other rocks, after compaction and natural settlement for a period of time, The red slate is muddy, firmly filled into the cracks of the rock, and the geotextile sinks the sand to build the dam. The dam formed is firm and dense, and it is not easy to form a dry beach, avoiding secondary dust. At the same time, it also saves a lot of land for storing waste ore. Waste ore can be used for paving and building materials.
(4) Construction of a circular economy industrial park
While producing iron concentrates, Luzhong Mining Group also uses wet smelting to leaching copper from copper-containing materials, and then reducing the compound products of copper or copper from the leaching solution to extend the industrial chain. The typical process flow is shown in Figure 1.
Figure 1 Copper refining process
The project uses copper produced from its own copper concentrate to produce cathode copper through a wet copper smelting process. After the project was put into operation, Luyuan Welfare Copper Factory changed its processing to process copper cathode for its own processing, saving freight, processing costs and reducing the loss of recovery rate. It can obtain an economic benefit of 4 million yuan per year.
Fourth, the exploration of developing mining circular economy
(1) Successful experience
Practice has proved that in order to meet the requirements of developing circular economy, energy conservation and consumption reduction, clean production, recycling of renewable resources, etc. must be the focus of technological innovation and technological transformation, increase investment in science and technology, and vigorously carry out various forms of production, learning and research. The Association actively introduces and trains scientific and management talents, strengthens international cooperation and exchanges, accelerates the introduction, development and promotion of advanced and applicable ecological recycling new technologies, new technologies and new equipment, accelerates the transformation of traditional production processes, and develops and produces recycled products. Promote the ecological transformation of production and management of enterprises. Accelerate the development of “circulation technology†such as long-term use of metal products that reduce resources and energy inputs, recycling technologies, and technologies that minimize waste emissions.
(2) The main problems
- Low comprehensive utilization. The total recovery rate of mineral resources in China is only about 30%, which is 20% lower than the foreign level. In terms of the recovery rate of the mining, the iron ore is 67%, the non-ferrous metal ore is 50% to 60%, and the non-metallic mineral is 20% to 60%. The plant with a comprehensive utilization rate of 75% of the beneficial components only accounts for 2% of the total number of selected plants, and more than 70% of the mines with associated minerals have a comprehensive utilization rate of less than 2.5%. What is more noteworthy is that the common (concomitant) components of some mines even exceed the value of minerals, but these co- (concomitant) components are not used in the tailings of the main minerals. According to reports, the amount of non-ferrous metals lost in tailings is 200,000 tons per year, with a value of more than 2 billion yuan. The utilization rate of foreign tailings can reach more than 60%, while China is only about 7%, the gap is very large. In terms of the recovery rate of the mining and mining group, iron is about 60%, copper metal is 20% to 25%, and the comprehensive utilization rate is lower than the advanced level at home and abroad.
-Low value-added products. At present, most mining enterprises have a single product, mainly selling primary products. The company has low profitability, is affected by the market, and has poor anti-risk ability.
- Insufficient investment, lack of motivation for technological innovation. For a long time, the comprehensive utilization of resources and tailings utilization projects have not received due attention. The lack of capital investment has led to aging equipment and backward technology, which has restricted the development of circular economy.
- Resources and environmental awareness are not high. The law and regulations for resource utilization are lagging behind, the basic management of tailings utilization is weak, and the incentive and restraint mechanism for comprehensive utilization of resources is lacking; the awareness of environmental protection is not strong, and the environmental governance of mining subsidence areas is backward.
(3) Countermeasures and recommendations
"Comprehensive utilization, turning waste into treasure, not only protects the national resources, but also purifies the environment, it can be said to be more than one item." It highly summarizes the necessity and urgency of comprehensive utilization of resources. In the new historical development stage facing the 21st century, China's limited resources will carry overloaded import and environmental burdens. It is impossible to continue to rely on resources and extension to expand the economic growth mode of reproduction. The comprehensive utilization of mine resources should further attract the attention of relevant departments, and practical measures should be taken from the aspects of policy, economy, law and technology.
- Change concepts and improve the comprehensive utilization rate of mineral resources. Mining enterprises should establish a long-term concept and comprehensively utilize mineral resources as a necessary measure to achieve sustainable development of the mining industry. It is necessary to strictly implement the “three rates†(mining recovery rate, depletion rate, ore dressing recovery rate) index management, and improve the utilization level of mineral resources. Develop and utilize associated ore and tailings; optimize the original technical parameters, such as mining cut-off grade and ore dressing recovery rate, and propose the best solution.
- Strengthening corporate management and improving the use of associated mines and tailings. Mining enterprises are the main body of comprehensive utilization of mineral resources. They are directly related to the comprehensive utilization rate of mineral resources. In addition to giving full play to the role of market mechanisms, they should also strengthen the macro management of integrated departments and incorporate resource utilization into national and industrial development planning and formulation. A step-by-step implementation plan. Mining enterprises must also make overall plans for this work. They must set up or designate specific management institutions, strengthen the supervision and coordination of internal resource utilization, and make the comprehensive utilization of mineral resources embark on a path of healthy development.
- Increase the scientific and technological efforts of mineral resources utilization. Strengthen the investigation of mineral resources, find out the basic types of mineral resources, particle size composition, various useful metals and non-metallic minerals, and the content of harmful components. According to the characteristics of regions and different types, find out from the technical and economic aspects. Its rational use of the route. It is necessary to increase investment in science and technology, actively research new technologies, apply new technologies, select new equipment and new materials, strengthen technology integration, and gradually improve the level of technical equipment for mining, utilization, and resource recovery of mineral resources.
- Establish and improve the legal system and incentive mechanism for the comprehensive utilization of mineral resources. Further improve the laws and regulations on the comprehensive utilization of mineral resources, and it is illegal to clarify the waste of resources. Establish an incentive and restraint mechanism to clarify the intensive use of mineral resources, and put comprehensive utilization in place in exploration, design, mining, and smelting; and provide tax reduction and exemption for off-balance mines, residual ore and other difficult-to-collect mines. Policy Support.
From an industry perspective, the state should further strengthen and guide the marketization of enterprises through policy and institutional arrangements, break the geographical division, go abroad, improve the concentration of the industry, and formulate problems for enterprises from the perspective of circular economy and sustainable development. System, long-term development plan.
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