Sustainable Mining and Metallurgy

Abstract:As an important basic raw material industry in the national economy, the nonferrous metal industry is characterized by high energy consumption, strong resource dependence and high pollution risk, and is one of the key industrial areas for promoting green transformation and upgrading. This paper introduced the framework and construction idea of green manufacturing standard system for non-ferrous metal industry, the status quo of standard development and its effectiveness, and put forward the focus of green manufacturing standardization in the future.

Abstract:The scientific and standardized accounting of carbon emissions, the active promotion of emission reduction incentives, and the strengthening of corporate carbon performance disclosure management, as the key basic work to cope with climate change, play an important role in the overall consideration of preventing global warming and promoting corporate development, and also provide important soft power support for Chinese mining companies to “go out” and undertake local social responsibilities. This paper listed the main international standards, mechanisms, initiatives and policy documents from five aspects, including carbon emission accounting, carbon footprint analysis, carbon emission reduction mechanism, carbon emission reduction target setting, and carbon performance disclosure, for the reference of domestic transnational mining practitioners and other relevant practitioners.

Abstract:Based on the production practice of intelligent grinding system of semi-automatic grinding process in a concentrator, the effect of important control parameters and operation conditions of semi-autogenous mill of intelligent grinding system were summarized and analyzed. Through the analysis of production practice data, it is found that the key control parameters of the intelligent grinding system are semi-autogenous mill speed, feeding size and grinding concentration. The speed of semi-autogenous mill is the most sensitive parameter to the control of intelligent grinding system, and the regulation effect is the most significant. It can quickly adjust the operation state of grinding system. The feeding particle size takes the second place, which can play a short-term adjustment role;the grinding concentration has the weakest sensitivity and can achieve fine adjustment. Through the collaborative control of the above key parameters, the processing capacity of the grinding system can be maximized, and the product size can be adjusted and controlled.

Abstract:In view of the problems of traditional crude tin refining technology such as long process flow, difficulty in impurity removal and heavy environmental pollution, a new process composed of “condensation and centrifugation, oxidation, continuous crystallization and vacuum volatilization” was proposed for refining of crude tin. The theoretical research on the removal of iron and arsenic by centrifugation, copper, nickel and antimony by oxidation, silver by continuous crystallization and lead and bismuth by vacuum volatilization of crude tin has been systematically carried out. The migration and distribution law of impurity components between solid-liquid and gas phases has been clarified. And small-scale, semi-industrial and industrial tests have been carried out. The experimental results show that the new green short-process refining technology of crude tin can produce 9999% refined tin, and the quality of refined tin can meet the national standard of 4N tin. Compared with the traditional crude tin refining technology, the new green short-process refining technology of crude tin has the advantages of strong adaptability of raw materials, less consumption of auxiliary materials, less discharge of “three wastes”, high direct tin yield, low slag rate sh, low comprehensive energy consumption, and low production cost.

Abstract:Based on the rapid development of new energy vehicles and the strong demand for nickel raw materials due to the development of high nickel content of ternary power batteries, the research on the production of low nickel matte by laterite nickel ore side-blown matte smelting is proposed. In this paper, the thermal decomposition behavior of gypsum was systematically studied by thermodynamics, and the effects of carbon to sulfur ratio and reaction temperature on CaS conversion were analyzed. The basic test of gypsum selective reduction of laterite nickel sulfide was carried out. On this basis, the expanded test of oxygen-enriched side-blown laterite nickel sulfide was carried out, and the reaction mechanism of gypsum selective reduction of laterite nickel sulfide and oxygen-enriched side-blown laterite nickel sulfide was summarized. The results show that the process of producing low nickel matte by direct reduction of nickel sulfide laterite ore with desulfurized gypsum in a short process is feasible. The process uses industrial solid waste desulfurized gypsum as a sulfurizer, which can make full use of Ca and S elements in the gypsum slag to achieve the goal of “green recycling and resource utilization of solid waste”. The nickel recovery rate is more than 90%, the cobalt recovery rate is more than 87%, the sulfur recovery rate is more than 75%, and the iron recovery rate is less than 60%, which can meet the requirements of nickel, cobalt The purpose of selective reduction, sulfuration and enrichment of iron.

Abstract:Separation of valuable metal ions from complex metal-ion solutions has always been the focus and difficulty in the field of hydrometallurgy, and solvent extraction is a mature method for complex ion separation. In this paper, the MHP acid solution in laterite nickel ore sulfuric acid process was taken as the research object. P20⁴⁺sulfonated kerosene was used as the extractant to separate Mg²⁺, Mn²⁺, Cu²⁺, Zn²⁺ from the MHP acid solution. The effects of P204 content, saponification rate, sulfuric acid concentration and extraction ratio (O/A) on the extraction, washing and stripping of impurities were investigated. The results showed that when the content of P204 in organic phase was 30%, the saponification rate was 65%, and the ratio of O/A was 2∶1, the single-stage extraction rate of Mn²⁺and Cu²⁺was more than 90%, and the extraction rate of Zn²⁺ was more than 70%. When the concentration of washing sulfuric acid is 0.4mol/L and O/A is 5∶1, the single-stage elution rate of Co²⁺and Mg²⁺reaches 40%; When the concentration of stripping sulfuric acid is 2.5mol/L and the O/A is 7∶1, the single-stage stripping rate of Mn²⁺, Cu²⁺and Zn²⁺reaches more than 80%. Through the process optimization of extraction, washing and stripping, the impurities such as Mn²⁺, Cu²⁺, Zn²⁺and Mg²⁺in the MHP acid solution can be effectively removed. This work, provide some useful information for the similar impurity removal process.

Abstract:In view of the outstanding problems of high output, large stock, complex types, complex composition and difficult treatment of industrial solid waste produced by copper, lead and zinc smelting in China, the types and disposal of industrial solid waste produced by copper, lead and zinc smelting in China were introduced in detail, including the treatment process and new technology of landmark industrial solid waste such as copper smelting slag, slag dressing tailings, white smoke, fuming furnace slag, cadmium smoke, zinc leaching slag, zinc volatilization kiln slag, etc. A new technical route for collaborative treatment of copper, lead and zinc smelting solid waste was proposed. Combined with the types and disposal characteristics of industrial solid waste produced by copper, lead and zinc smelting, a comprehensive copper, lead and zinc smelting base or industrial park, and coordinate the treatment of industrial solid waste produced by copper, lead and zinc smelting should be constructed, which can effectively improve the comprehensive recovery rate and utilization efficiency of valuable metal elements and reduce the comprehensive smelting cost.

Abstract:Photovoltaic power generation is gradually occupying an important seat in the world energy landscape due to its advantages of cleanliness, safety and abundant resources, and will become one of the ‘main forces’ of world energy supply in the future. With the rapid development of the upstream and downstream of the photovoltaic industry chain, the price of polycrystalline silicon as the basic raw material continues to rise, resulting in a rising investment heat in the polycrystalline silicon industry. This paper introduced the current development status and future trend of photovoltaic polysilicon industry, analyzed the main technical route adopted by polysilicon production at home and abroad, trichlorosilane method and silane method, and analyzed the energy consumption and cost composition of trichlorosilane method. Based on the perspective of cost and regional advantages, this paper put forward reasonable judgments and suggestions for the development pattern of photovoltaic polysilicon industry. The production cost of polycrystalline silicon is mainly affected by power consumption and the price of metal silicon powder. In the future, the polycrystalline silicon industry will be transferred to the western region with energy endowment and rich silicon mineral resources.

Abstract:Considering the energy crisis, environmental problems and the constraints of lithium resources on the development of lithium battery industry, the recycling of waste lithium batteries is a very necessary and meaningful work. In this paper, the recycling methods of waste lithium iron phosphate battery cathode materials were reviewed, including chemical precipitation method, selective leaching method, mechanochemical method, electrochemical lithium extraction method and other valuable element extraction technologies, as well as solid phase repair regeneration, hydrothermal repair regeneration, electrochemical repair regeneration and other repair regeneration technologies, and the advantages and disadvantages of different recycling methods were pointed out. In view of the problems existing in the recycling of spent lithium iron phosphate battery cathode materials at the present stage, the prospect was put forward, which provide a reference for the subsequent research and industrial application of spent lithium iron phosphate battery recycling.

Abstract:With the rapid development of electronic products and electric vehicles, spent lithium-ion batteries grow rapidly. At present, most of the research focuses on the recovery of the positive and negative materials of spent lithium ion batteries, while ignoring the recovery and utilization of the electrolyte. Organic solvents and lithium salts in electrolyte have high recovery value. This paper summarized the principle and application of current recovery and treatment methods of spent lithium-ion battery electrolyte, including high-temperature thermolysis, distillation-condensation method, chemical method and supercritical CO₂ extraction method, compared the advantages and disadvantages of different recovery methods, and look forward to the development direction of electrolyte recovery process.

Abstract:Aiming at the problems of long recovery process, high lithium loss rate and low purity in the traditional method of lithium recovery from waste ternary power battery black powder, a process of priority extraction of lithium by sulfation roasting was proposed. In this paper, the thermodynamic feasibility of lithium extraction by sulfation roasting was analyzed. The effects of different sulfate, concentrated sulfuric acid addition, calcination temperature and calcination time on lithium extraction were studied. The results of sulfation roasting experiments of different sulfates show that the lithium yield is about 95% when concentrated sulfuric acid, sodium bisulfate and ammonium sulfate are used for sulfation roasting. The roasted material obtained by adding sodium bisulfate is harder; the roasted material obtained by adding concentrated sulfuric acid is fluffy and honeycomb-like; the material after roasting with ammonium sulfate is powder, which is easy to break, but will produce ammonia gas. Lithium phosphate can not be obtained by roasting with the same amount of sodium sulfate, so concentrated sulfuric acid is selected for sulfation roasting. The optimum conditions for the preferential extraction of lithium are as follows: the amount of concentrated sulfuric acid is 105% of the theoretical amount, the calcination temperature is 600℃, and the calcination time is 2h. Under these conditions, the lithium yield can be as high as 95.2%. The prepared lithium carbonate and lithium phosphate have low impurity concentration and high purity.

Abstract:Based on the main problems existing in sludge treatment and disposal in China, this paper gave a detailed interpretation of the Implementation Plan for Sludge Harmless Treatment and Resource Utilization jointly issued by the National Development and Reform Commission, the Ministry of Housing and Urban-Rural Development of the Peoples Republic of China and the Ministry of Ecology and the Environment of the Peoples Republic of China. The sludge treatment in China has problems as follow：sludge quality is poor and is difficult to treat; the work starts late, the capital investment is not in place, and the handling capacity is insufficient; the land use is limited, and the sludge outlet has not been completely opened. Under the background of “Carbon Peaking and Carbon Neutrality”, sludge treatment and disposal in China should follow the basic principles of “comprehensive consideration, adaptation to local conditions, government-led, market operation, stable and reliable, green and low-carbon”, standardize sludge treatment methods, actively promote sludge land use, reasonably reduce the landfill scale, orderly promote sludge incineration alone or in coordination, and increase the promotion of sludge energy and material recycling. For sludge treatment facilities, the efficiency of existing facilities should be improved and the incremental construction should be done well, and the process management should be strengthened and the safeguard measures should be improved. For sludge treatment, it is necessary to take harmless treatment as the goal and resource utilization as the means to complement the shortcomings, and gradually form a complete chain of theories, technologies, equipment, policies, standards and price systems for sludge safe treatment and resource utilization, so as to promote the healthy development of the industry.

Abstract:Promoting county-level domestic waste disposal is an important link and basic work in strengthening county-level economic and social development and infrastructure construction in China. This paper summarized the significance, principles and difficulties of garbage disposal in county-level areas of China, introduced the concept of solid recovered fuel (SRF) and its main technical routes, advantages and related standards, and analyzed the feasibility of preparing SRF from garbage in county-level areas from the aspects of national policies, actual needs, technical conditions and investment costs. Combined with the actual situation, the SRF solution for domestic garbage preparation in county-level areas of China was given.

Abstract:Urban sludge contains a large number of pathogenic microorganisms, heavy metals and other pollutants, and its output has increased sharply in recent year. If it is not handled properly, it will pollute the environment and endanger human health. At present, Chinas urban sludge disposal methods include landfill, compost, land use, incineration, etc. Sludge incineration is currently the most thorough, rapid, safe and effective method for sludge disposal. This paper summarized the research and application progress of sludge incineration from the aspects of the development history, incineration mode and incineration device, systematically sorted out various influencing factors of sludge incineration process, and compared various indexes and parameters of fluidized bed incinerator, multi-chamber incinerator, rotary kiln incinerator, grate incinerator and other incinerators. Under the background of “double carbon” and in combination with the development trend of sludge resource utilization, it is proposed that mixing urban sludge and waste into derivative fuel, developing circular economy and reducing carbon emissions is also an effective way to reuse the surplus value of urban sludge.