China Nonferrous Metallurgy

Abstract:Copper foil is an important part of lithium battery as the negative current collector that is the main factors of the cycle life and stability of battery. It determines the internal resistance of lithium battery. With the improvement of the requirements for the energy density and cycle life of lithium battery, the requirements for the relevant properties of electrolytic copper foil, such as the roughness and micro morphology of surface, are also improved accordingly. Because of its porous structure and large specific surface area, 3D porous copper foil can effectively improve the stability and cycle life of lithium-ion battery. Promoting the commercial application of 3D porous copper foil has become one of the main research directions of lithium-ion battery cathode materials at this stage. In this paper, several methods of preparation processes of porous copper foil and their relevant electrochemical performance are reviewed. Porous copper foil negative current collector has great significance to improve the performance of lithium-ion batteries. This paper provide the reference for engineers and researchers of copper foil.

Abstract:Platinum and palladium are important precious metals, which are often recovered in the process of electrolytic silver. In the process of producing silver products, a smelting enterprise needs to determine platinum and palladium in high-silver nitric acid decomposition solution and palladium precipitation solution. Inductively coupled plasma optical emission spectrometry (ICP-OES ) has the advantages of high sensitivity, low detection limit, wide linear range, simultaneous detection of multiple elements, rapid and accurate, and has been widely used in recent years. However, the method to the determination of platinum and palladium in nitric acid decomposition solution and palladium precipitation solution has not been applied in the present literature. In this paper, ICP-OES method was used to determine platinum and palladium in high-silver nitric acid decomposition solution and palladium precipitation solution. The results of high-silver matrix interference test, organic palladium precipitation agent interference test, fire assay enrichment test and different acid media tests were compared. The following conclusions are drawn. The silver matrix interference phenomenon is not obvious, and there is no need to separate the silver matrix. The organic palladium precipitation agent has no interference on the determination results. The viscosity of sulfuric acid makes the determination results deviate, and the best digestion method should be nitric acid system digestion. The results of the fire assay enrichment method is 30% lower for palladium and 38% lower for platinum, and the loss is large. Platinum and palladium in high-silver nitric acid decomposition solution and palladium precipitation solution were determined by ICP-OES method after digestion with nitric acid system, and the recovery rate was within 95%-105%, and the relative standard deviation was less than 5%, which were stable and reliable. The test shows that the method is convenient to operate and has strong practicability. It can be used for actual analysis of platinum and palladium in high-silver nitric acid decomposition solution and palladium precipitation solution.

Abstract:At present, more than 90% of the arsenic-containing dust and wastewater produced by smelters are converted into solid waste, forming arsenic-containing waste residue. Due to the lack of appropriate treatment methods or high cost of treatment and disposal, the harmless treatment and comprehensive utilization of arsenic slag are limited. The solidification of arsenic-containing waste residue is a good treatment method at present. The main technologies include cement solidification, geopolymer solidification and mineral residue solidification. Cement solidification is a relatively mature and most widely used technology, but the long-term stability of the solidified body is not good, and arsenic ions are easy to leach; geopolymer has a wide source of materials and a good arsenic fixation effect, but it often requires high temperature conditions to consume a lot of energy; the solidification of arsenic by mineral residue adhesive can basically achieve ‘zero addition’ of cement, reduce the use of cement and reduce energy consumption. It is the best choice for single curing technology at present. Through the comparative analysis of the literature, it can be seen that a solidification technology is difficult to carry out large-capacity and long-lasting sealing of arsenic-containing waste residue, and the combined use of the three technologies is better. At present, the mechanism of cement solidification and geopolymer solidification has not yet formed a standard, and the mechanism of mineral residue solidification has been clearly studied. In the later stage, it is necessary to strengthen the mechanism and process of joint solidification technology, and further evaluate the environmental risk of solidified materials.

Abstract:Red mud is rich in iron resources and contains a certain amount of rare metals. If it is stored and disposed, it will not only cause great harm to the environment, but also waste metal resources. Based on the analysis of the output and composition of red mud, this paper focuses on the new technology of iron and scandium recovery from red mud and the research progress in the preparation of building materials. The metal extraction effect of red mud treatment process is better and the valuable elements can be recovered step by step. The disadvantage is that the iron concentrate grade is low and the cost is high. The wet process technology is simple and has low cost and energy consumption, but it has the disadvantages of large acid consumption, simultaneous leaching of multiple elements, and difficult harmless treatment of waste liquid. The distribution and separation of iron and scandium in red mud can be realized by the combined process of pyrometallurgy and hydrometallurgy. The disadvantages are complex process flow, high cost and high energy consumption. Because red mud contains a large amount of sodium alkali, there will be ‘frosting’ and other phenomena in the production of cement and other building materials, which inhibits its application in the field of building materials. Therefore, the low-cost, green and large-scale utilization of red mud is still a difficult problem for the future aluminum industry. The author believes that the following aspects can be studied and studied：pretreatment of red mud into ultrafine powder to improve the dissolution rate；study the closed-loop process in the metal recovery process to minimize the generation of waste liquid ; the process of removing alkali and reducing radioactivity of red mud was studied, and it was coordinated with other industrial waste residue and waste liquid to realize the treatment of waste by waste.

Abstract:Guangxi is the main production base of alumina, with an annual output of about 15 million tons of red mud. The red mud contains high iron, and is rich in rare, dispersed, and rare earth metal elements, which has great resource recovery value. The four goals for achieving high value comprehensive utilization of red mud are harmless treatment of alkali, thorough separation of iron and aluminum, enrichment of “three rare” elements, and low-cost treatment.This paper comprehensively analyzes the current status of comprehensive utilization technology of red mud, and considering the rich agricultural and forestry resources in Guangxi, proposes a process route of using biomass gas reduction roasting high iron red mud-leaching-magnetic separation. Pyrolysis gas carbon cogeneration technology can convert Guangxi’s rich agricultural and forestry wastes into high-quality combustible gas. The by-product of gasification is biomass charcoal, which can be used as a reducing agent in the alkali reduction roasting process, significantly reducing the cost of auxiliary materials.The red mud mixed with sodium carbonate is subjected to reduction roasting and then wet grinding for dissolution. The main component of the dissolution liquid is sodium aluminate, and aluminum hydroxide and sodium carbonate are recovered. After magnetic separation of iron ore, the remaining part is the “three rare” enriched slag, which can recover titanium, scandium, rare earth, etc.The proposed process route achieves complete separation of iron and aluminum and enrichment of “three rare” elements, and can be processed at a low cost. The added alkali can be recycled, providing a new path for low-cost and efficient utilization of Guangxi red mud and recovery of “three rare” metals.

Abstract:Coal fly ash is the main solid waste produced by coal-fired power plants. Besides rich in aluminum, fly ash also contains valuable elements such as gallium and lithium, which is a potential extraction resource of valuable metals such as aluminum, gallium and lithium. The traditional alkaline process, alkaline solution process and acid process can not meet the requirements of low energy consumption, low reagent consumption, low emission and high recovery. Other new processes, such as hydrochemistry, vacuum thermal reduction and carbothermic chlorination, have the advantages of less slag production and environmental protection, but are still in the stage of small laboratory trials. The content of gallium and lithium in fly ash is relatively low, the recovery process generally includes precipitation, solvent extraction and resin adsorption. Resin adsorption has the advantages of good selectivity and small environmental pollution, but it is mainly used in alkaline system. The cooperative recovery of aluminum, gallium and lithium is an important way to realize the resource utilization of fly ash. The “one-step acid dissolution” process is the most promising technology in the utilization of fly ash resources, with the extraction of alumina as the main line and the extraction of gallium and lithium and the preparation of silical-aluminum based materials as the secondary lines. In the future, the recovery of valuable metals in fly ash needs to be strengthened in the following aspects: developing new sintering technology and comprehensive utilization of silicon calcium slag, to completely solve the problem of high energy consumption and large amount of waste slag in alkali process; increasing the research and development of inorganic non-metallic material modification, to solve the problem of equipment corrosion in acid process; developing inexpensive extractants and adsorbent resins, or developing more efficient impurity removal processes, to reduce the investment cost of acid processes.

Abstract:Treating low-uranium wastewater directly by natural bentonite has limited removal efficiency. The adsorption capacity will increase significantly after modification, but the current modification technologies are more complicated. In the paper, CTAB/CTS-B adsorption material was successfully prepared with cetyltrimethylammonium bromide and chitosan as modified materials, and characterized by SEM, EDS, XRD, XPS and FTIR. In this work, the adsorption performance and mechanism of CTAB/CTS-B for uranium were mainly studied. The results showed that the maximum removal rate of CTAB/CTS-B for low-concentration uranium-containing wastewater was more than 99% under the conditions of pH 7, dosage 3g/L, adsorption time 2h, rotational speed 180r/min and room temperature. The adsorption process conforms to the pseudo-second-order kinetics and Elovich kinetics equation, and the adsorption behavior is complex with Langmuir equation. Thermodynamic analysis showed that the adsorption enthalpy changed to negative, ΔG⁰ 0, adsorption entropy change ΔG⁰ 0. Analysis of adsorption mechanism showed that ion exchange, electrostatic adsorption, C-C, C-O, amino, hydroxyl and carbonyl played an important role in the adsorption of uranium by CTAB/CTS-B, and the removal of uranium was still good after five cycles, indicating that CTAB/CTS-B has good reusability. CTAB/CTS-B has good adsorption capacity for low-uranium wastewater, and the synthesis technology is relatively simple, which is more suitable for application and promotion.

Abstract:In order to realize the efficient utilization and recovery of molten steel slag waste heat resources and element resources, aiming at the problem of temperature drop caused by heat loss during slag transportation, a two-dimensional heat transfer model of slag-clad interface was established by numerical simulation. The effects of changing the insulation structure of slag cladding and the temperature of baking slag ladle on the temperature drop and insulation effect of slag during slag transportation were studied, and the economic analysis of insulation cladding structure was further carried out. The results show that compared with the traditional slag ladle, the temperature drop of slag can be significantly reduced by using the insulation wall structure, and the slag temperature drop decreased by 42~75℃. The insulation effect of magnesia-alumina spinel castable combination in slag ladle working layer is more obvious than that of magnesia-carbon brick combination, and the temperature drop is reduced by 30℃. The average temperature drop rate of slag edge decreased from 14.11℃/min to 4.26℃/min after preheating of baking slag ladle. The economic analysis results of heat preservation effect of different wall structures show that When the magnesia alumina spinel castable is 120mm, the high alumina castable is 110mm, and the lightweight insulation brick is 20mm are used in slag ladle wall, the economy of heat preservation effect is the best, which can save 195kW·h electric heating, and is beneficial to realize efficient recovery and utilization of slag heat.

Abstract:A large amount of waste containing In-Bi will be produced during processing the new high-performance transparent conductive oxide film (IBO). In addition, with the wide application of IBO, IBO waste target will also increase. In the process of vacuum distillation for separation and purification, the saturated vapor pressure of In and Bi is similar, so it is difficult to obtain satisfactory process parameters. The vapor-liquid equilibrium (VLE) phase diagram can be used to guide the practice of vacuum distillation. In this paper, vacuum distillation experiments were carried out with the configured In-Bi alloy as raw material to obtain the VLE value of In-Bi alloy, and MIVM was used to predict the activity and gas-liquid equilibrium data of In-Bi alloy components. The following conclusions were obtained. under the conditions of system pressure of 5~10Pa and distillation temperature of 1183K, when the In content in the residue is 80.80%, the Bi content in the volatiles reaches 97.17%, which indicating that the In-Bi alloy can be separated by vacuum distillation. The molecular interaction volume model (MIVM) was used to calculate the activity of components of In-Bi alloy. The average standard deviations of the calculated values and the experimental data were ± 0.0139 and ±0.007, respectively, and the average relative deviations were ±11.216% and ±11.4521%, respectively. The results show that the MIVM is reliable for predicting the activity of In-Bi alloy. The vapor-liquid equilibrium (VLE) data of In-Bi alloy was predicted based on the MIVM. A comparison shows that the predicted value is consistent with the experimental data determined in this study, which indicates that the MIVM is reliable for predicting the VLE value of indium-based alloys and can be used to guide the separation of indium-based alloy by vacuum distillation. The reliability of the MIVM model was verified and the process parameters for vacuum distillation separation of indium-based alloys are also optimized based on the model prediction and vacuum distillation experiments. This study will provide guidance for vacuum separation and purification of indium-based alloys or processing of complex materials containing indium.

Abstract:At present, when dealing with copper-nickel alloy, the pyrometallurgical process has the problems of repeated smelting of materials, large turnover, dispersion of precious metals and low recovery rate; The hydrometallurgy process has the problem of difficult separation of copper and nickel in the full immersion solution. Based on the analysis of the composition of copper-nickel alloy, this paper carries out experimental research on copper-nickel alloy produced by the nickel smelter. In the first stage, CuSO4 was used as the leaching agent to convert nickel and nickel sulfide into nickel ions into solution, while copper ions form precipitates and enter the residue. In the second stage, sulfuric acid was added to the leaching residue and oxygen was introduced to leach copper and copper sulfide, and precious metals were enriched in the residue. The three-stage process concentrates and crystallizes the copper sulfate solution. The results show that the total residue yield is 4.61%, the total leaching rate of copper is 99.19%, the total leaching rate of nickel is 99.43%, and the enrichment multiple of precious metals is 21.69. The copper leaching solution was concentrated and crystallized, and the purity of copper sulfate crystal was 98.35%, which met the first-class standard requirements of copper sulfate crystal products. The process has less reagent consumption and no wastewater discharge. It is a green metallurgy process and has promotion value.