Sustainable Mining and Metallurgy

Abstract:Vanadium oxides, especially vanadium pentoxide, have attracted much attention as energy storage battery materials in clean energy because of characteristics such as their variable valence, layered structure, suitable for ion storage and market competitiveness of raw materials with abundant resources and low price. On the basis of introducing the properties of vanadium oxides, this paper reviewed the research status, existing problems and development trend of solid vanadium-based batteries such as vanadium-based lithium ion batteries, vanadium-based sodium ion batteries and vanadium-based zinc ion batteries. At present, vanadium-based battery technology has been significantly improved. Although solid vanadium-based battery technology has not beenused in practical application, it has greatly improved in battery specific capacity, rate capability, energy efficiency and cycle stability.

Abstract:Direct carbon solid oxide fuel cell （DC-SOFC）is an energy conversion device with high output efficiency, simple structure and high fuel utilization. Although the development of direct carbon solid oxide fuel cells has a long history, the research depth is low. In this paper, the working principle, thermal effect and structure type of direct carbon solid oxide fuel cell were systematically introduced. The research progress of carbon fuel and anode materials of direct carbon solid oxide fuel cell at home and abroad was reviewed. The advantages and disadvantages of the battery and the related literature patents were analyzed. The future development trend of DC-SOFC was prospected.

Abstract:CO₂ hydrogenation to methane is an important technical means to achieve carbon emission reduction and provide clean energy (CH₄). The key to realize this technology is the preparation of high-performance catalysts. In this paper, a Ni-Cu-Al trimetallic nickel-based hydrotalcite derived catalyst (NCA) with high selectivity and excellent reaction stability for CO₂ methanation was designed. The hydrotalcites with different Ni/Al molar ratios were prepared by urea hydrolysis method by adjusting the ratio of Ni to Al on the laminate. The hydrotalcites were used as precursors to prepare NCA catalysts. The performance of each catalyst was evaluated by XRD, TGA and BET characterization methods, and the long-term stability of the catalyst was tested. The results show that with the increase of the molar ratio of Ni/Al, the crystallinity of the catalyst is better, the thermal stability is increased, and the incorporation of copper can improve the stability of the catalyst. Under the temperature of 300℃ and pressure of 0.1MPa, the conversion rates of CO₂ over the several catalysts were above 60%, and the conversion rate of CO₂ over the catalyst with Ni/Al molar ratio of 3.5 was 82.6%. After 70h of reaction, the conversion rate did not change significantly, which shows that the catalyst has good stability.

Abstract:Eutectic solvents have excellent characteristics such as low melting point, high solubility and easy preparation, and have attracted extensive attention in the field of hydrometallurgy. As a new “green” solvent, eutectic solvents not only avoid the equipment corrosion problems caused by traditional acid leaching or alkali leaching, but also greatly reduce costs and reduce environmental pollution. In this paper, the composition, classification and physicochemical properties of existing eutectic solvents were comprehensively reviewed, and the research progress of eutectic solvents in the leaching of metal minerals and metal oxides was emphatically introduced, and the future development trend of eutectic solvents was prospected according to the existing problems.

Abstract:Phosphogypsum is a bulk solid waste produced in the process of phosphoric acid hydrometallurgy, and its stacking has caused serious harm to the environment. Aiming at the problem that phosphogypsum is difficult to be recycled due to low whiteness and high SiO2 content, the influence of kerosene, sodium oleate and waste engine oil on flotation purification of phosphogypsum was studied by taking phosphogypsum produced by a phosphorus chemical enterprise in Guizhou as the research object. The results show that waste engine oil can effectively remove impurities such as SiO2 and organic matter in phosphogypsum, and the flotation effect is the best. The optimum conditions for the removal of phosphogypsum by waste engine oil are as follows: the pH value of pulp is 2.0, the concentration of flotation pulp is 20%, the amount of waste engine oil is 40g/t, and the amount of MIBC is 300g/t. Under the optimum experimental conditions, the concentrate yield is 91.72%, the whiteness is 63.43%, the grade is 97.54%, and the effective separation of dihydrate gypsum and organic matter is realized. This study has important guiding significance for the subsequent realization of resource and high-value utilization of phosphogypsum.

Abstract:Copper electrolytic refining is an important part of copper smelting, and electrode short circuit is unavoidable in the process of electrolysis. Therefore, this paper proposed a lightweight short-circuit detection algorithm based on YOLOv8 to effectively solve the problem of short-circuit detection under complex heat distribution. First, advanced technologies of ShuffleNet and SqueezeNet were integrated. A feature extraction module was added to the YOLOv8 framework, reducing model parameters while maintaining feature extraction capability, thereby improving the detection speed of the algorithm. Secondly, to solve the problem of insufficient detection accuracy and poor correlation, according to the characteristics of short-circuit data set, the loss function was optimized and each loss weight was reassigned, which effectively improved the detection accuracy. Finally, the experiment results show that the improved algorithm not only maintains high detection accuracy, but also reduces resource consumption, and the average accuracy (mAP) is increased to 0.854.

Abstract:Lead electrolytic refining is the key process of crude lead purification. The higher the lead ion concentration in the electrolyte, the greater the specific resistance, the higher the DC power consumption, and the higher the production cost. On the premise of not affecting the chemical composition of lead electrolyte, through theoretical analysis, this paper useed insoluble graphite anode electrowinning method instead of traditional sulfuric acid precipitation method to reduce the concentration of lead ions in electrolyte. The results show that under the conditions of current intensity of 11000A, single cell electrolyte circulation of 50L/min and electrowinning time of 120h, the concentration of lead ions in the electrolyte decreases by 14.9g/L, and the quality of lead precipitation by electrowinning is better than the conventional electrolysis of lead, in which the grade of antimony impurity elements decreases significantly. Compared with the traditional sulfuric acid precipitation method, the cost of lead removal by insoluble graphite anode electrodeposition method is reduced by about 451 yuan/t.

Abstract:The production process of aluminum electrolysis emits harmful gases and dust, which pollutes the environment and endangers human health. Driven by national environmental protection policies, the transformation of aluminum electrolysis cells for pollution reduction and carbon emission reduction has become a research focus. The article reviews the current situations and problems in four key areas of aluminum electrolysis cells: sealing optimization, in-cell flue gas collection, inter-cell exhaust control, and residual electrode flue gas collection, and summarizes the transformation and optimization plans.In terms of sealing improvement, strengthening the sealing of anode guide rods and cell cover plates can enhance the gas collection efficiency. Regarding the optimization of in-cell flue gas collection, both online transformation and transformation during cell shutdown can improve the gas collection effect, and the online transformation has obvious advantages. In inter-cell exhaust control, by replacing valves with orifice plates or reducing pipes, the exhaust uniformity and efficiency are improved. For residual electrode flue gas collection, multiple methods are adopted, among which the residual electrode cooling system performs remarkably.These technological improvements and process optimizations are of great significance for improving the workshop environment, reducing fluoride emissions, enhancing energy utilization efficiency, and achieving the green and sustainable development of the aluminum electrolysis industry.

Abstract:In the context of increasing global energy constraints and stricter environmental requirements, the aluminum electrolysis industry has come under widespread scrutiny due to its high energy consumption and carbon emissions. This paper systematically studied new energy-saving technologies for aluminum electrolysis cells, focusing on the principles and application of cathode phosphorous-iron casting technology, composite copper-inserted steel bar technology, self-balancing busbar technology，dual-side gas collection technology，new anode steel stubs, and prebaked anode slotting technology. These technologies have demonstrated significant potential in reducing energy consumption, with the lowest direct current consumption in aluminum electrolysis reaching 12200kWh/t-Al. The application of these technologies helps alleviate the energy-saving and carbon-reduction pressures faced by aluminum electrolysis production enterprises while enhancing production safety and stability.

Abstract:In order to improve the current efficiency, reduce the power consumption per ton of aluminum and prolong the service life of aluminum reduction cells, an electrolytic aluminum plant used a fully graphitized cathode to replace the 50% graphite cathode of the original 500kA aluminum reduction cell. Because the fully graphitized cathode has the characteristics of high conductivity, high thermal conductivity, strong resistance to sodium erosion and small thermal expansion coefficient, the voltage management of the fully graphitized cathode aluminum electrolytic cell is different from that of the 50% graphite cathode aluminum electrolytic cell in the production process. In this paper, the causes of abnormal phenomena such as voltage jump in roasting stage, high noise value in abnormal period and cold tank in normal production period in the production process of 500kA series fully graphitized cathode aluminum electrolytic cell were analyzed, and the voltage management strategies in each period were given.

Abstract:This paper introduced the harm and influence of high sulfur minerals and high carbon minerals in domestic bauxite on the Bayer process production process, systematically combed the current application status of desulfurization and decarbonization technology, and emphatically introduced the practice of desulfurization, desiliconization and decarbonization process in an alumina enterprise. Combined with the characteristics of bauxite in Sanmenxia area of Henan Province, the alumina enterprise proposed a positive flotation synchronous desulfurization and desilication process for low-grade high-sulfur bauxite after process modification and collector formula optimization. Under the premise of desilication rate of 60%-65%, the desulfurization rate of 60%-70% can be obtained. A reverse flotation desulfurization process was proposed for high-sulfur bauxite with sulfur content greater than 2.0%, and the desulfurization rate reached about 85%. At the same time, combined with the advantages of sintering process and Bayer process, a low-cost process decarburization process was proposed, and the decarburization rate reached about 30%. Focusing on the combination of source impurity removal and process impurity removal is the direction of efficient and economical utilization of high-sulfur and high-carbon bauxite in the future.

Abstract:In this paper, leaching experiments were carried out on the smelting slag produced by the process of treating anode slime produced by gold-copper smelting in Kaldo furnace by using environmentally friendly cyanide-free reagents, and the effects of grinding fineness, liquid-solid ratio, regent concentration and leaching time on the of gold and silver were investigated. The test results show that the leaching rates of gold and silver can reach 95.60% and 88.79% respectively under the conditions of grinding fineness of -0.023μm (600 mesh) accounting for about 90%, liquid-solid ratio of 2∶1, environmentally friendly cyanide-free reagent concentration of 1.2% and leaching time of 24h. For the leaching solution containing gold and silver, the content of gold and silver in the solution can be reduced to 0.1g/m3 and 1.2g/m3 respectively by zinc powder replacement, and the recovery effect of gold and silver is good. The above results show that it is feasible to leach gold and silver from Kaldo slag by non-cyanide environmental protection agent. This process is environmentally friendly and has high recovery rate of gold and silver.

Abstract:In this paper, the possible chemical reactions of lead, zinc and arsenic in the process of oxygen-enriched side-blown bath smelting in copper smelting were sorted out. The distribution and trend of lead, zinc and arsenic in smelting slag, matte, flue gas and soot were studied, and the final product forms of lead, zinc and arsenic were determined. In view of the white soot produced in the process of pyrometallurgical copper smelting, the present situation of its comprehensive utilization was summarized, and the development trend of comprehensive utilization of white soot resources was put forward.

Abstract:Large-scale and high-intensity exploitation of coal resources inevitably leads to a large number of mine environmental problems, in which the ground collapse is more prominent, not only seriously disturbed and destroyed the land resources, it also threatens the safety of peoples lives and property. On the basis of summing up the types and distribution of ground subsidence in Inner Mongolia, this paper systematically expounded the forms and remote sensing response characteristics of coal mine ground subsidence, and analyzed and constructs the factor system of influencing the remote sensing response of ground subsidence. Through the study of remote sensing response to coal mine ground subsidence, the disadvantages of traditional field survey such as long period, slow data updating and heavy workload can be effectively compensated, it provides the technical basis and reference for the scientific prevention and control of the coal mine ground subsidence in Inner Mongolia.

Abstract:The generation of municipal solid waste (MSW) is increasing annually worldwide. Reasonable disposal of MSW can not only avoid environmental pollution risks, but also contribute to resources recycling. In this paper, MSW was compressed to solid recovered fuels (SRF), and the influence of moisture content and composition of MSW and molding pressure on the expansion rate and impact resistance of SRF were analyzed. The results show that increasing the proportion of paper or reducing the proportion of plastics can reduce expansion rate and increase impact resistance of SRF; and reducing the proportion of fruit peels, or increasing the proportion of nutshells and textiles appropriately can enhance impact resistance of SRF, while ensuring good expansion rate. The calorific value of SRF prepared in this experiment meets the requirements of relevant standards of ISO TC300 and can be traded as a fuel product.

Abstract:Taking a certain urban pollution treatment plant as the research object, through means such as data collection,personnel interviews,and on-site inspections,the pollution production links and pollution pathways were analyzed and judged,concluding that the site required a second phase of soil pollution condition survey.The second phase of the survey set up 11 soil monitoring points,4 groundwater monitoring points, and 7 sewage monitoring points. The test results showed that all indicators in the soil did not exceed the standards;the exceeding factors in the groundwater are total hardness,manganese,dissolved total solids,and sulfide,which were not characteristic indicators of the sites pollutants;there were some indicators exceeding the standards in the water and sludge in the pools,but the soil and groundwater monitoring data showed that there is no leakage of water and sludge.According to relevant specifications,this site did not need further investigation,the soil pollution condition survey work was concluded.