Sustainable Mining and Metallurgy

Abstract:As an important basic industry of the national economy, the green transformation of the non-ferrous metal industry is conducive to improving market competitiveness and influence, and is also a strategic need for the overall green development of the country. This paper introduces the metal production, consumption, energy consumption and carbon emission data of the non-ferrous metal industry, analyzes the existing problems in the non-ferrous metal industry, and introduces several advanced typical green low-carbon technologies. Finally, it looks forward to the future development direction and trend of the non-ferrous metal industry, analyzes the opportunities and challenges of green low-carbon development in China's non-ferrous metal industry, which provides reference for promoting industrial adjustment, accelerating green transformation.

Abstract:Leaching residue of laterite nickel ore, as a by-product of sulfuric acid high-pressure acid leaching (HPAL) for nickel and cobalt extraction, is rich in valuable metals such as iron and chromium. Its large-scale stockpiling is not noly a waste of resources but also has a risk of heavy metal contamination. This study used a reduction roasting-reduction smelting process to recover valuable metals from the leaching residue. The results show that under the conditions of adding 2.0% anthracite, roasting temperature of 900℃ and roasting time of 45min, the sulfur content of leaching residue decreases from 3.57% to 0.056% and the desulfurization rate reaches 98.69%, which can effectively eliminate the influence of sulfur on the subsequent smelting. For reduction smelting of the roasted calcine, under the conditions of carbon ratio 0.85, alkalinity 0.9, smelting temperature 1550℃ and smelting time 30min, the recovery rates of iron and chromium are 94.41% and 59.79%, respectively. The resulting alloy can partially substitute conventional steelmaking raw materials, while the slag is suitable for producing active admixtures. This process provides a novel technical pathway for the comprehensive resource utilization of laterite ore leach residue.

Abstract:As a green and efficient energy conversion medium, solar cells have been widely used in the world in recent years. With the rapid development of the photovoltaic industry, the number of retired photovoltaic modules is increasing. How to efficiently recycle and utilize retired photovoltaic modules has become an important issue for the photovoltaic industry. Based on the introduction of the structure and composition of crystalline silicon photovoltaic modules, this paper briefly described the characteristics of the main methods of resource recovery of decommissioned photovoltaic modules, and summarized the application research progress of silicon materials recovered from decommissioned photovoltaic modules in the fields of silicon wafer repair and regeneration, silicon powder regeneration to manufacture silicon anode materials, and silicon powder application in silicon alloys at home and abroad, in order to provide ideas for finding an economical, efficient and clean silicon material recovery method for retired photovoltaic modules.

Abstract:Indium-containing dust, including lead smelting dust, copper smelting dust, zinc smelting dust, steel dust, etc., is an important raw material for extracting rare metal indium. Hydrometallurgical leaching is the main process for treating indium-containing dust. In this paper, the current situation of hydrometallurgical leaching of indium from indium-containing dust was comprehensively reviewed. At the same time, the characteristics and limitations of different processes such as high temperature and high acid leaching, oxidative acid leaching, mechanically enhanced acid leaching, extenal field enhanced leaching, acidification roasting leaching on indium metal and insoluble indium phase leaching were compared and analyzed, and the problems of each process in industrial production practice were pointed out. In addition, the research progress of selective extraction of indium by new leaching agent-deep eutectic solvent was analyzed, and the prospect of industrial application of deep eutectic solvent in hydrometallurgical leaching of rare metals such as indium was put forward.

Abstract:The modification of the melt source is an effective approach to reduce the TiO2 content in high-titanium slag and improve its hydration activity, which will enhance its value as an auxiliary cementitious material in cement and concrete. This study proposed the use of steel slag to regulate the slag system's alkalinity and TiO2 content, achieving high-titanium slag melting and melt modification in graphite crucibles. The melt was then rapidly cooled through water quenching to prepare steel slag-modified high-titanium slag. The results indicate that with the addition of steel slag, the alkalinity of the high-titanium slag melt increases, and the iron oxide content in the modified high-titanium slag decreases, suggesting that the melting and modification process can recover metallic iron. The glass content of the modified high-titanium slag is always above 75%, but it decreases as the alkalinity increases. As the alkalinity increases, the TiO2 content in the system decreases, weakening its stabilizing effect on the glass structure, which leads to an improvement in the hydration activity of the modified high-titanium slag micro-powder. The modified high-titanium slag micro-powder with an alkalinity of 1.5 meets the requirements of S75-grade granulated blast furnace slag powder for cement mortar flowability and activity index.

Abstract:Aiming at the problems of long process, high acid consumption and low recovery rate of lithium in the conventional recycling process of spent ternary lithium battery black powder, combined with the actual production situation, a series process of reduction roasting-two-stage acid leaching for lithium extraction was studied. The structural transformation of lithium ions in the cathode black powder was realized by carbothermal reduction roasting pretreatment, and then the pH condition of the solution was controlled by stages for two-stage dilute acid leaching. In this process, there is no need to add additional impurity removal agent, which realizes the efficient separation of lithium and cobalt, nickel and manganese impurity elements. The effects of different roasting temperature, roasting time, dosage of carbonaceous reductant, liquid-solid ratio, leaching time, leaching temperature and sulfuric acid concentration during acid leaching on lithium extraction were investigated by single factor method. The results show that the leaching rate of lithium is 97.23% and the leaching rate of cobalt, nickel and manganese is less than 0.6% under the conditions of reducing agent ratio of 15%, sintering temperature of 600℃, roasting time of 100min, leaching liquid-solid ratio of 6mL/g, leaching time of 120min, leaching temperature of 70℃, and sulfuric acid concentration of 1mol/L. The lithium precipitation precursor prepared by this process was further precipitated with sodium carbonate, resulting in a direct lithium yield of 88.61%.

Abstract:A lead smelter adopts lime-iron salt method to treat waste acid wastewater, but there are some problems, such as unstable operation, difficulty in reaching the standard of water quality, high risk of thallium pollution and high cost of slag treatment. In order to solve the above problems, this paper used the process of “sulfidation + one-stage neutralization + two-stage deep neutralization” to optimize the treatment process of waste acid wastewater. The feasibility of the vulcanization method was verified on the basis of comparing the vulcanization agents, analyzing the subsequent process and analyzing the properties of the slag. Using this process, the removal rate of arsenic and thallium in the vulcanization stage reached more than 99%, and by controlling the pH value of the end point of the reaction to be 2.5-3.0, the content of heavy metals in the gypsum slag was less than 0.05%, and the quality of gypsum slag could be effectively guaranteed. The process of neutralization + iron salt + deep oxidation/vulcanization was adopted in the second stage of neutralization and deep treatment. By controlling the pH value of the reaction end point at 7.5-8.5, and the heavy metal content of the final effluent could reach the standard. The process produced three kinds of slag, most of the heavy metal pollutants were removed in the form of sulfide precipitation by vulcanization. The sulfide slag was a hazardous waste containing thallium ; the gypsum residue produced by neutralization of a section of gypsum was general hazardous waste; the content of thallium in the neutralization slag produced by the second stage neutralization was less than 20g/t, which belonged to hazardous waste. All three kinds of slag have disposal destinations. By changing the nature of the slag and returning to the furnace for disposal, more than 65% of the hazardous waste slag can be reduced.

Abstract:Solid butyl xanthate is usually used as collector to recover copper metal in flash smelting slag beneficiation. Solid butyl xanthate is easy to wet and harden in the actual production process, and there are many problems such as high labor intensity, high safety risk, unstable concentration of artificial dispensing, poor working environment and high pressure of environmental protection. Taking the flash smelting slag of a copper smelting enterprise as the research object, the research and application of aqueous xanthate were carried out from the aspects of prescription research and development, drug property comparison, drug validity period and drug concentration control. The results show that the new aqueous xanthate, which is composed of 70% liquid butyl sodium xanthate + 27% liquid amyl sodium xanthate + 3% stabilizer, can replace the solid xanthate when the concentration is controlled less than or equal to 40%. The effective use period of the new aqueous xanthate is less than or equal to 28 days. It has been proved by industrial practice that the water agent xanthate has both copper sulfide and copper oxide metal collecting ability, which can reduce the loss of copper metal in tailings and has obvious economic benefits.

Abstract:Oslo crystallizer is a typical crystallizer commonly used in continuous industrial crystallization process, and its crystallization effect directly affects the quality of the final crystallization product. In this paper, CFD fluid simulation software was used to calculate the distribution of solid phase in the crystallizer at different heights (500mm, 700mm, 900mm, 1100mm, 1300mm, 1500mm) from the lowest point of the feed downcomer to the bottom of the crystallizer under uniform particle size. The influence of the insertion depth of the downcomer on the internal flow field of the Oslo crystallizer was obtained, and the optimal design size of the downcomer structure was determined and optimized. The results show that when the lowest point of the feed downcomer is 900mm from the bottom of the crystallizer, the Oslo cooling crystallizer can operate normally and is conducive to the discharge of high-concentration materials. Based on the simulation results, a variable diameter tube is added at the bottom of the feed downcomer. This structure can effectively improve the distribution of the flow field inside the crystallizer, increase the concentration of the discharged crystal, and provide a reference for the structural design of the Oslo cooling crystallizer.

Abstract:In view of the problems of difficult and incomplete separation of selenium and mercury in the treat ment of copper smelting acid mud, this paper innovatively used copper as a separating agent without introducing new impurities to effectively separate selenium and mercury in the acid mud. The specific process flow was acid mud chlorination leaching-copper precipitation separation mercury-sulfur dioxide reduction precipitation selenium-sulfurization precipitation copper. The test was carried out on the factors of separating selenium and mercury. The results showed that under the premise of reaction temperature of 20℃ and selenium concentration in the solution not higher than 20g/L, the sodium metabisulfite was used to adjust the potential of the solution to about 700mV, and then the separation agent copper was added to separate selenium and mercury. When the end point potential was about 450mV, the reaction ended. At this time, the reduction rate of mercury was greater than 98%, and the mercury content in the solution after reduction was less than 200mg/L. The grade of mercury slag obtained was about 80% and the selenium content was less than 1%, which achieved the purpose of effective separation of selenium and mercury.

Abstract:In this paper, the sulfur content in copper concentrate was determined by high frequency infrared carbon sulfur determinator, and the optimum instrument condition parameters were determined. At the same time, the sample weight and flux addition of copper concentrate samples were studied. The experimental results show that the high frequency infrared carbon sulfur determinator can quantitatively determine the sulfur content in copper concentrate samples, and the relative standard deviation is 0.30%-0.51%. The results are in good agreement with the results of combustion-titration method. Using high frequency infrared carbon sulfur determinator to determine the sulfur content in copper concentrate, can effectively shorten the time of sulfur analysis and detection, and realize the rapid determination of sulfur. The precision and accuracy are high, which meets the requirements of production control.

Abstract:Graphitized cathode, high conductive steel rod and phosphorus pig iron casting technology have been gradually applied in electrolytic production and achieved certain results. In this paper, the advantages of graphitized cathode and high conductive steel bar, as well as the steps and key points of phosphorus pig iron pouring were introduced. Based on the production practice, the economic indexes such as assembly voltage drop, furnace bottom pressure drop, voltage and current efficiency after start-up of cathode electrolytic cell assembled by graphitized cathode + high conductive steel bar + phosphorus pig iron casting and cathode electrolytic cell assembled by semi-graphitic cathode + ordinary steel bar + paste tamping were compared. The results show that the cathode structure assembled by graphitized cathode + high conductive steel rod + phosphorus pig iron casting can not only effectively reduce the iron-carbon voltage drop between the cathode carbon block and the steel rod, but also improve the current efficiency, reduce the power consumption and improve the stability of the electrolytic cell operation, which has a good effect of energy saving and consumption reduction.

Abstract:In this paper, potassium chloride was recovered from the electric dust of alumina rotary kiln by water leaching method. The effects of different treatment conditions on the recovery of potassium chloride from fly ash in the processes of water leaching dissolution, impurity removal and purification, and segmented crystallization were investigated. The effects of liquid-solid ratio, seed addition and other factors on the separation and purification of KCl were investigated. The test results show that the effective recovery rate of potassium chloride is more than 90%, and the KCl product is a single phase, which meets the industrial potassium chloride standard. The process of extracting potassium chloride by water immersion method is simple, safe, low equipment requirements, energy saving and environmental protection, which provides a new idea for the resource utilization of electric dust collection in alumina rotary kiln.

Abstract:The minimum diameter of the deep cone thickener is determined by its unit area processing capacity. The cone angle is generally taken as the empirical value of 30°-60°. In the design, they are taken by experience according to the basic properties of the material, which has certain subjective blindness. In this paper, the diameter and cone angle of deep cone thickener were optimized by numerical simulation. Firstly, the underflow concentration at different time points after feeding was obtained by carrying out the thickening experiment on the large-scale model thickening experimental machine with diameter d=180mm and height h=2m. Then, the experimental results were compared with the simulation results. The results show that the root mean square error is less than 0.5, which verifies the accuracy of the simulation results. Finally, based on the actual situation of a mine, the cone angle and diameter of the deep cone thickener are optimized by simulation technology. The results show that under the condition that the unit area processing capacity of the deep cone thickener is 40t/h, the cone angle of the thickener is 30° and the diameter is 11m, the underflow concentration is the highest in the same time, and the time to reach the highest concentration is the shortest. The simulation solves the subjective blindness problem in the parameter design of deep cone thickener, which can be promoted and applied.

Abstract:In the process of mining resource development and environmental protection, exploring the optimal ratio of production investment to ecological investment is essential for maximizing the comprehensive benefits of mines. To find the balance point between economic benefits and ecological benefits, the paper analyzes the key elements of comprehensive benefits in green mines and their role in balancing economic benefits and ecological benefits, and studies the relationships between comprehensive benefits, marginal benefits, and marginal costs in green mines versus traditional mines, and between small mines and large mines, revealing the economic decision-making principles for green mine and highlighting its stronger market competitiveness and profitability compared to traditional mines. Furthermore, this paper elaborates on the interaction mechanism between six balances and comprehensive benefits elements in green mine construction, proposing optimization strategies to maximize comprehensive benefits. Overall, this paper provides theoretical support and practical guidance for green mine construction, promoting the transformation of the mining industry towards a greener and more sustainable development model.

Abstract:Anode guide rod group is an important conductive component in electrolytic aluminum production. Its conductivity and service life are important indicators to measure economic benefits. In order to solve the problem of quality instability in conventional welding, this paper analyzed the disadvantages of current automatic welding, and proposed a structural energy-saving anode guide rod group robot welding scheme. The groove cutting, positioning and clamping, visual inspection and welding process of the anode guide rod group were reformed in an all-round way. The welding processes such as bidirectional double bead surfacing of anode steel claw and direct welding of anode guide rod steel-aluminum were used and improved to solve the problems of welding cracking, damage and high pressure drop. The production practice shows that the pressure drop of the structural anode steel claw is significantly lower than that of the cast steel claw. Compared with the traditional cast steel explosive welding block, the weld pressure drop of the steel-aluminum direct welding guide rod group can be reduced by 13.84mV, and the pressure drop fluctuation is small, stable below 20mV, and the conductivity is significantly improved. Using steel-aluminum direct welding, with 92.5% current efficiency calculation, per ton of aluminum can save electricity by about 44.6kW·h, and the energy saving effect is obvious.