China Nonferrous Metallurgy

Abstract:Industrial energy management is an advanced and efficient means of energy conservation and emission reduction, which manages the energy in a centralized and systematic way to reduce costs and increase efficiency for enterprises. It is also an essential link in the implementation of intelligent transformation, digital transformation, and the work of carbon neutrality and carbon peaking in the metallurgical industry. However, few studies on energy management have been reported at the metallurgical industry level, and the differences and common problems of energy management between steel and non-ferrous metallurgy have not been discussed. In view of this problem, this paper first comprehensively analyzed the development of energy management in metallurgical industry, and then discussed the application logic, scope and effect of energy management in the metallurgical industry, then sorted the relevant national laws, policies, standards, certifications and typical energy-saving evaluation indicators, and finally analyzed energy management cases of steel and non-ferrous metallurgy production enterprises at home and abroad. It is believed that there are still problems in China's energy management in the metallurgical industry, such as insufficient energy monitoring, emphasising local areas but neglecting the overall situation, and a shortage of professional talents. In the future, attention needs to be paid to establishing a quantitative evaluation standard system, introducing low-carbon and energy-saving new technologies, tracking the entire process of resource footprints, integrating intelligence and digitization, and large-scale use of clean energy. With the deepening of energy-saving concepts, innovations breakthroughs in energy-saving new technologies, the improvement of energy quantification evaluation systems, incentives for carbon reduction economic benefits, and the continuous strengthening of ESG (Environmental, Social and Governance) by enterprises, energy management will undoubtedly usher in broader development opportunities.

Abstract:Bauxite resources are a scarce mineral resource in China, with a large amount of high sulfur bauxite resources. However, the smelting of high sulfur bauxite will reduce the Al₂O₃ leaching rate, decrease the settling performance of red mud, pollute aluminum hydroxide products, and corrode production equipment. Therefore, desulfurization technology of high sulfur bauxite has become the key to achieving efficient and comprehensive utilization and alleviating the shortage of bauxite resources. At present, the desulfurization technology of high sulfur bauxite mainly includes pre-treatment desulfurization and leaching process desulfurization. Pre-treatment desulfurization includes flotation, calcination, electrochemical desulfurization, microbial desulfurization, etc. The flotation method is suitable for aluminum ore resources with low sulfur content. However, for low-grade and high sulfur aluminum ore, there are problems such as high dosage of flotation reagents and large discharge of wastewater; The desulfurization efficiency of the roasting method is high, but traditional stacking roasting has problems such as long roasting time and high energy consumption; Electrochemical desulfurization has advantages such as low temperature, atmospheric pressure, high desulfurization rate, and no secondary pollution, but there are problems such as high energy consumption and limited production scale; Microbial desulfurization has lower production costs and energy consumption, and higher environmental friendliness, but specific bacterial strains have strict requirements for growth environment and long cultivation cycle. The desulfurization process of dissolution includes oxidation evaporation desulfurization, precipitation desulfurization, and lime desulfurization. The oxidation evaporation method can remove most of S^2- from sodium aluminate solution, but its effect on the oxidation of other forms of sulfur is not significant; The precipitation method for desulfurization is relatively simple, but it has the problem of high cost of desulfurizers and difficulty in practical production; The lime method can only remove SO^2-₄ from the solution and does not have a significant removal effect on other types of sulfur ions. In the future, it is recommended to address the desulfurization problem of high sulfur bauxite in the following directions: developing low-temperature, high-efficiency, and low-energy consumption roasting processes; Improve or develop new desulfurization and capture agents; Screening efficient and easy to cultivate bacterial strains, and studying the desulfurization effect of mixed bacteria.

Abstract:In recent years, the gradual depletion of zinc ore resources has led to a decline in the grade of most zinc concentrates in the world, and the scale of mining and utilization of low-grade zinc minerals has gradually expanded. However, the composition of low-grade ore is complex. After pretreatment and leaching, there are still many impurities accompanied by zinc ions entering the solution, causing anode corrosion, increasing power consumption, and affecting the surface morphology of precipitated zinc. In this paper, the corrosion mechanism of manganese ion, aluminum ion, iron ion, sulfate ion, bromide ion, fluoride ion and chloride ion on anode materials in zinc electrowinning is analyzed, and the removal methods of each impurity ion are given. The corrosion of fluorine and chloride ions to the anode is relatively obvious. Both of them corrode the anode by destroying the lead dioxide oxide film on the surface of the lead anode. The literature results show that the F^- concentration in zinc electrolyte should not exceed 0.03g/L, and the Cl^- concentration should be controlled below 0.1g/L. In the process of zinc electrowinning, the concentration of F^- and Cl^- should be reduced as much as possible, and anode materials that can resist F^- and Cl^- corrosion should be used.

Abstract:The annual new steel slag discharge in China is more than 100 million tons, and the utilization rate is only 10%~20%. There are abundant resources such as “slag, iron and heat ” in the liquid steel slag of converter, which causes great waste by simple storage or landfill. At present, the mainstream technologies of steel slag granulation mainly include hot stuffy method, air quenching granulation method, drum method, etc., which are all based on the development of steel slag granulation and free calcium oxide (f-CaO) digestion, which is convenient for subsequent crushing, screening and magnetic separation to obtain slag steel, magnetic separation powder and tailings. Although these methods have solved the problems of large investment, large land occupation and heavy pollution in other methods to a certain extent, there are still some problems such as incomplete utilization of steel slag resources, risk of volume stability, high grinding cost and high iron content. The author proposes to use the combination of modified reconstruction and gas-water two-phase mixed fluid quenching granulation technology to treat steel slag. This method adds acid flux and reducing agent to liquid steel slag, and uses the high speed of gas and the high thermal conductivity of water to quickly cool the liquid steel slag into solid particles, which reduces the fibrosis of steel slag and takes into account the granulation of reconstructed slag and the efficiency of waste heat recovery. The tailings after iron extraction can be used in the fields of building materials preparation, soil modification, glass-ceramic and ceramic materials after particle size classification. However, this method is still in the research stage and not mature enough. In the later stage, it is necessary to carry out in-depth research on the preparation of high-performance steel slag granulation materials, environmental protection utilization and resource utilization, and the development of steel slag deep processing.

Abstract:Centrifugal extraction method is an extraction method that enhances mass transfer between two phases through high-speed rotation and utilizes centrifugal force field to achieve two phase separation quickly. To improve the vanadium extraction efficiency and the separation factor of vanadium （V）and iron, the centrifugal extraction method was applied to the study of vanadium purification and enrichment process from black shale acid leaching solution. Under centrifugal extraction conditions with an initial pH value of 2.0, organic phase composition of 15 vol.% P204+85 vol.% sulfonated kerosene, phase ratio（O/A）of 1∶4, extraction time of 4 min, extraction temperature of 45℃, and stirring speed of 1400r/min, the V extraction efficiency was 87.67%. Compared with the conventional extraction, the separation factor of V/Fe increased from 41.78 to 127, and the extraction saturation capacity of vanadium increased from 52.63g/L to 70.45g/L, indicating that centrifugal extraction method can effectively enhance the separation effect of vanadium and iron, and improve the extraction saturation capacity of vanadium.

Abstract:Cobalt matte is one of the commonly used raw materials for cobalt smelting, which is rich in components such as cobalt, copper, and iron. Its chemical properties are stable, and conventional leaching methods cannot effectively dissolve valuable metals. Moreover, its hardness is high, making it difficult to treat abrasives. This article takes imported cobalt matte particles as the research object, and systematically examines the feasibility of the cobalt matte chlorine acid leaching treatment process from the aspects of grinding equipment selection, chloride leaching test, verification test, and industrial test. The main conclusions are as follows: vibration abrasive can effectively treat cobalt matte particles with high hardness, and the discharge particle size of cobalt matte after abrasive treatment is 90% below 150μm, with a power consumption of 1.2kg/kW·h; Under the conditions of a liquid solid mass ratio of 6∶1 between 15% hydrochloric acid and cobalt matte, a mixing speed of 60r/min, a reaction temperature of 95℃, a reaction time of 8 hours, and the simultaneous introduction of chlorine gas, the leaching rates of copper and cobalt in cobalt matte reached over 90%, and the leaching rate of iron reached over 70%; In industrial experiments, the abrasive and leaching process were optimized, and the abrasive power consumption was reduced to 4kg/kW·h. The leaching rates of copper, cobalt, and iron all reached over 98%, with a significant improvement in the effect. After removing iron and copper by the goethite method, the leaching solution can obtain a cobalt rich solution, and the amount of leaching residue is small, which can be well applied in industrial production.

Abstract:Nano-ZnO is a new type of high-function fine nano-material with wide application. The nano-ZnO particles prepared by hydrothermal method have high purity, good crystal shape and simple operation. There are many impurity elements in the zinc leaching solution containing zinc secondary resources, which has a great influence on the purity of the later products, among which the removal of copper and cadmium is more critical. In this paper, the zinc leaching solution containing zinc secondary resources was used as raw material, and copper and cadmium were removed by zinc powder replacement. Then, the purified zinc sulfate solution was used as zinc source, and ammonia water, sodium carbonate and sodium hydroxide were used as precipitants to prepare nano-ZnO by hydrothermal method. The effects of different process parameters on morphology of nano-ZnO were investigated. The results show that under the appropriate conditions, the concentrations of copper and cadmium ions in the leaching solution after zinc powder replacement are 0.0399mg·L^-1 and 6.4162mg·L^-1 respectively, which can be used to prepare nano-ZnO. The products prepared by using ammonia and sodium carbonate as precipitants are a mixture of ZnO and other crystals, which are irregular crystals of non-pure phase. Pure nano-ZnO can be prepared by using sodium hydroxide as precipitant. The optimum preparation conditions are as follows: the molar ratio of zinc to alkali is 1∶2, the reaction time is 1h, and the reaction temperature is 120℃. The prepared nano-ZnO presents a prism structure, the particle size is between 50~100nm, and the particle size distribution is uniform.

Abstract:Lead-based solid waste is a common waste produced at both production and consumption ends, and has a strong pollution effect. Its green treatment technology is a key link to achieve the prevention of lead containing waste pollution. The collaborative treatment of lead based solid waste by double-bottom blowing process is an economical and reasonable way to treat lead based solid waste. Comparing with the traditional ore lead smelting, its production operation is more complex for co-processing lead solid waste. In order to ensure its production status in a stable and economic state, there are higher requirements for its process control system. A set of online intelligent optimization control system for lead-based solid waste collaborative smelting process has been developed by China ENFI Engineering Corporation. The whole system is integrated of online optimization control system, intelligent early warning and efficient monitoring system and system database, which mainly realizes the following functions : ① In response to the low level of automation in treatment process, based on smelting process mechanism and big data of production operation, a prediction model of key parameters of smelting process is established by applying computer modeling and neural network method, and a set of online optimization control system for lead-based solid waste collaborative smelting is developed; ② Using the workshop reality model as the carrier, an intelligent early warning and efficient monitoring system for lead-based solid waste synergistic smelting is established to realize the digitalization and visualization of industrial signals, scenes and processes; ③ The control system integrates the relevant hardware and software on site, and displays the data interaction and collaborative operation between the modules in detail, forming an intelligent, efficient and safe synergistic smelting workshop.

Abstract:As a crucial equipment in the smelting process, the performance of the lance directly influences the stirring effect of the airflow on the melt. In this study, a physical model of an immersed multi-channel lance with a length of approximately 800mm used in the anode slime side-blown furnace was established. Numerical simulation studies of gas flow and heat transfer processes inside the lance were conducted based on the SSTk-ω turbulence model. The distribution characteristics of gas temperature, flow velocity, and pressure inside the lance were analyzed. The variation characteristics of airflow pressure along the flow direction under different flow rates of natural gas and oxygen-enriched air, the relationship between flow rate and outlet velocity, and the cooling effect of airflow rates on the lance were investigated. The findings suggest that the multi-channel structure of the lance enhances the outlet velocity and reinforces the cooling effect of the gas flow. However, significant pressure loss occurs at abrupt changes in the cross-section of the airflow channel and at the outlet section, hindering the enhancement of the outlet velocity. With the increase of airflow rates, the outlet velocity of the lance increases significantly, and the pressure loss at the outlet segment of natural gas and oxygen-enriched air reaches 40% and 25% of their inlet total pressure, respectively. Additionally, the cooling effect of flow rate on the lance is significant, with a decrease of approximately 15K in the temperature of the outlet section for every increase of 5Nm³·h^-1 and 10Nm³·h^-1 in flow rate for natural gas and oxygen-enriched air, respectively.

Abstract:Aluminum and aluminum alloys have strong corrosion resistance, very low loss and high recycling value. Promoting the recycling of spent aluminum can significantly reduce energy consumption and carbon emissions in the aluminum industry. In this paper, the process of downcycling, equivalent recycling and upcycling of spent aluminum is summarized, and the advantages and disadvantages of each process are analyzed. The traditional spent aluminum remelting degradation regeneration process can not completely remove the alloying elements and metal impurities in aluminum, recycled aluminum can only be degraded, but with the increase of recycled aluminum, the traditional degradation utilization technology will not be able to use so much recycled aluminum. Grade protection recycling can maximize the value of spent aluminum resources, but only a very small number of high-quality spent aluminum alloys can realize its inherent value, and it is difficult to achieve most of the spent aluminum resources. Spent aluminum Upcycling technology can separate aluminum and alloying elements, so that the recovered aluminum can reach the quality level of primary aluminum, and can realize the complete regeneration of spent aluminum, which is the best way to recycle waste aluminum. Molten salt electrolysis is the most promising technology for extracting aluminum from spent aluminum.

Abstract:Red mud (RM), fly ash (FA) and phosphogypsum (PG) have the characteristics of large production and low utilization rate, and long-term storage will have a serious impact on water resources, soil and air. In this paper, phosphogypsum is proposed to replace alkali lime CaO, and three kinds of solid wastes are co-treated with high temperature sintering, alkali leaching of aluminum and magnetic separation of iron. The effects of sintering process conditions on the recovery of aluminum and iron are investigated. Under the conditions of sintering temperature 1100℃, holding time 30min and calcium ratio 2.0, the iron recovery rate reaches 79.2%, iron grade reaches 74.5% and aluminum dissolution rate reaches 75.9%. Increasing the sintering temperature is conducive to the recovery of iron and aluminum, but the clinker will appear sticky and hinder the dissolution of aluminum when the temperature is higher than 1100℃. The holding time has little effect on the recovery of aluminum and iron. CaO and Na₂CO₃ help to activate the activity of mullite in fly ash and improve the recovery rate of aluminum. At high temperature, Fe₃Ti₃O₁₀ and Ca₃Fe₁₅O₂₅ will be formed when phosphogypsum is added in excess, which leads to the decrease of iron grade and iron recovery. Using this test process, every 1t of red mud, 0.5t of fly ash and 1.5t of phosphogypsum can recover 75.9% of aluminum and 0.3t of iron concentrate, and the alkali cycle can be realized in the production. At the same time, the generated 2CaO·SiO₂, 2CaO·SiO₂ and other by-products can be used to prepare sulfoaluminate cement. The whole process realizes the coordinated consumption of three kinds of solid waste, and effectively realizes the comprehensive utilization of resources.

Abstract:Secondary aluminum ash contains a large amount of alumina, aluminum and aluminum nitride, as well as some fluorides and chloride salts, which are hazardous wastes. At present, the commonly used aluminum recovery technologies, acid leaching method and alkali leaching method, have the problems of harsh process conditions, low recovery rate, high energy consumption, large material consumption and low added value of products. In this study, alkali sintering method was used to recover alumina from secondary aluminum ash. The effects of sintering temperature on aluminum nitride conversion, alkali aluminum ratio, sintering time and forming method on alumina recovery were investigated, and the main conclusions were obtained as follows. Under the experimental conditions of sintering temperature 1423K, sintering time 40min, alkali to aluminum ratio 1.1 and dry pressing, the maximum dissolution rate of alumina is 94.23%. Through the analysis of the composition and phase of the leaching residue of sodium aluminate clinker of secondary aluminum ash, the main components of the clinker after calcination by alkali sintering method are Al₂O₃ and Na₂O, accounting for 49.70% and 28.06% respectively, and the main components of the residue after standard leaching of clinker are CaO, Al₂O₃ and MgO. The contents were 25.46%, 20.27% and 15.80%, respectively; The decomposition rate of AlN in secondary aluminum ash is higher, which can reach more than 95%, and the leaching toxicity of resource products is below 30mg/L. In summary, this paper uses alkali sintering method for resource utilization of secondary aluminum ash, and realizes harmless treatment of secondary aluminum ash for nitrogen removal and fluorine fixation, which has the advantage of high utilization rate of environmentally friendly resources, and lays a theoretical foundation for subsequent large-scale industrialization.

Abstract:Blast furnace gas ash is one of the main solid emissions from steel companies, rich in valuable elements and a valuable secondary resource.Due to the different raw materials of various enterprises, the composition of blast furnace gas ash is complex and has its own characteristics, with major elements intermingled. A single treatment process cannot meet the treatment requirements of blast furnace gas ash.This article aims to address the high content of K, Zn, and Pb in the blast furnace gas ash of Baotou Steel, and based on the analysis of the composition and phase of the raw materials, uses a water washing-potassium extraction-carbothermic reduction-dilute acid leaching process to extract and separate K, Zn, and Pb. The following main conclusions are drawn.The zinc and lead in the gas ash mainly exist in the form of oxides, while the potassium and sodium elements mainly exist in the form of chloride and sulfate salts. Various elements are intermingled and combined, resulting in a complex structure;The optimal process parameters for extracting potassium by water washing are a water washing time of 20minutes, a temperature of 90℃, and a liquid-solid ratio of 10∶1. Under these conditions, the potassium dissolution rate can reach 84.4%. The remaining potassium is solidified in aluminum silicate structures formed by doping multiple elements and cannot be dissolved;The optimal experimental conditions for carbothermic reduction of lead and zinc enrichment are 8% carbon content, 1400℃ reduction temperature, and 3h reduction time. Under these conditions, the zinc content in the reduction slag decreases from 3.61% to below 0.005%, and the lead content decreases from 1.28% to below 0.005%. The removal rate is above 90%;The lead-rich zinc powder was leached with 10% dilute sulfuric acid, and the zinc was dissolved and separated in the form of sulfate, resulting in a insoluble residue rich in elemental lead with a lead content of 77.22%.In actual production, chlorine gas can be used to dry waste sulfuric acid instead of 10% sulfuric acid in this process flow, which not only improves the environmental protection of the process, but also realizes the resourceful reuse of waste sulfuric acid.

Abstract:Longnan City has a large number of zinc mines and zinc smelters, and has a large number of walnut green peel resources. Based on the adsorption of zinc ions by activated carbon, in this paper, walnut green peel was carbonized at different temperatures, the activated carbon was modified by NaCl, HCl and NaOH, and the adsorption effect of modified activated carbon on zinc ions in wastewater containing zinc was investigated under different conditions. The results showed that the walnut green peel carbonized at 500℃ had the best adsorption property, which was denoted as WP-500. WP-500 modified by NaOH had the strongest adsorption capacity for zinc ions, and the modified activated carbon was denoted as WP3-500. When the dosage of WP3-500 was 4g/L, the temperature was 30℃, and the time was 30min, the removal rate of WP3-500 for zinc ions was 81.11%, and the adsorption capacity was 10.14mg/g. The results of kinetic analysis show that the quasi-first-order kinetic model can describe the adsorption behavior of WP3-500 on zinc ions, which is mainly controlled by physical adsorption. Compared with the preparation of adsorbents from waste biological materials such as corn straw, peanut husk and rice husk, the preparation of activated carbon from walnut green peel is simpler and cheaper, and the removal effect of zinc ions is better. This study provides a new idea for the resource utilization of walnut green peel and the removal of zinc ions from wastewater.

Abstract:The green and efficient extraction of titanium resources from titania-bearing blast furnace slag is a powerful guarantee for the continuous development of high-value-added titanium products. However, there is a lack of key thermodynamic data related to titania-bearing oxide slag systems, which seriously restricts the development of related titanium extraction processes. Based on the composition and mineral characteristics of typical titania-bearing blast furnace slag, combined with the “Phase Diagram” module of FactSage 8.2 thermodynamic software and the “FactPS” and “FToxid” databases, the evolution of equilibrium coexisting phases was determined in the temperature range of 1400~1600℃ and the oxygen partial pressure range of 0.21~10-18atm in the present work. The results show that when the temperature is constant, as the oxygen partial pressure decreases, the range of the liquid phase region first increases and then decreases, and titanium is reduced step by step; While the oxygen partial pressure is constant, as the temperature increases, the liquid phase region gradually enlarged, the liquid phase-CaTiO₃ first increases slightly and then decreases slightly with the increase of temperature, and moving in the direction of increasingw(CaO)/w(SiO₂) ratio. The liquid phase-TiO₂ first increases greatly and then decreases slightly. The research results are important for understanding the evolution of titania-bearing phases under different process parameters, and then developing a more environmentally friendly and more efficient titanium resource extraction process.

Abstract:In view of the lack of systematic thermodynamic analysis and thermal analysis of calcium roasting of vanadium slag, thermogravimetric analysis (TG) and differential scanning calorimetric analysis (DSC) were conducted on the roasting process of vanadium slag mixed with CaCO₃ or CaO. The phase transformation mechanisms during roasting process were analyzed, and the main conclusions were drawn as follows. It is feasible to produce calcium metavanadate, calcium pyrovanadate and calcium orthovanadate in the range of 350-960℃ during calcified roasting of vanadium slag. The calcination process of vanadium slag is mainly composed of four reaction stages which are interconnected or overlapping, namely, metal Fe oxidation stage, iron olivine oxidation and decomposition stage, spinel oxidation and decomposition stage of vanadate formation stage, silica-calcium reaction and pyroxene decomposition stage. The control temperature of phase transformation in the roasting process is: the oxidation of metal iron in the range of 350-700℃, the oxidation and decomposition of iron olivine in the range of 500-750℃, the oxidation and decomposition of spinel in the range of 500-900℃ and the decomposition temperature of silica-calcium reaction and pyroxene is generally above 900℃. These results can provide theoretical support for temperature control in production site.

Abstract:The resource utilization of silica slag and lead slag has problems such as complex recovery process and low utilization rate of valuable resources. However, the market demand for ferrosilicon alloy is large, and the research on the preparation of ferrosilicon alloy by lead slag has not been reported. In this paper, based on the analysis of the composition and phase of silica slag and lead slag, the thermodynamic analysis of the possible reactions was carried out by Gibbs free energy function method and HSC Chemistry software, and the preparation of ferrosilicon alloy was carried out according to the analysis results, and the following main conclusions were obtained:. The reaction of silicon with iron oxide to produce iron, the reaction of silicon with iron to produce FeSi, FeSi₂, Fe₃Si, Fe₅Si₃, and the reaction of silicon carbide with iron to produce FeSi could be carried out spontaneously within 298~2400K, but the reaction limit decreased with the increase of temperature. The ease of ferrosilicon generation is Fe₃Si＞Fe₅Si₃＞FeSi＞FeSi₂. The reaction between C and SiO₂ and the reaction between SiC and SiO₂ could not be carried out in the forward directionwhen the temperature was lower than 1900K. Through the experimental process of mixing-melting-water crushing-ball milling-screening, ferrosilicon containing Fe₃Si, Fe₅Si₃ and other phases can be prepared, which proved that the synergistic preparation of ferrosilicon by silica slag and lead slag was completely feasible, which provided a new idea for the resource utilization of the two waste slags.