China Nonferrous Metallurgy

Abstract:Nano-micron materials play an important role in the field of new energy. Spray pyrolysis technology is regarded as a promising technique for the industrial-scale production of nano-micro powders, owing to its short process flow, continuous operation, low production cost, and pollution-free reaction. Additionally, spray pyrolysis technology offers advantages such as minimal powder agglomeration, uniform particle size distribution, high specific surface area, controllable chemical composition, and excellent particle flowability, which is widely used in the synthesis of composite materials. This article summarizes research achievements in the preparation of key materials via spray pyrolysis technology, including conductors and catalysts, multi-purpose materials, solar cell materials, lithium-ion battery materials, and fuel cell materials. It was found that most studies focus on exploring the influence of process parameters on the properties of target materials, while some studies focus on synthesizing composite materials with specific structures and optimizing their properties. Currently, achieving large-scale production of fine powders with particle sizes below 5μm is a major challenge for spray pyrolysis technology: powders produced by pneumatic atomization can be easily mass-produced but have larger particle sizes, limiting their industrial application scope; ultrasonic atomization can produce submicron powders (below 5μm) but is difficult to scale up. Based on literature research, future development efforts should focus on two aspects: first, in the technical research domain, there is an urgent need to deepen the understanding of the mechanisms of spray pyrolysis technology and its operational processes; second, in the field of engineering applications, equipment and atomization processes must be optimized and improved, such as enhancing atomization nozzles or incorporating methods to promote particle size reduction. Furthermore, it is essential to actively integrate spray pyrolysis technology with other material preparation techniques to further explore the advantages of combined technologies and improve material performance.

Abstract:Driven by energy transformation and carbon neutrality, Li-CO₂ batteries have become a frontier energy storage technology due to their high energy storage efficiency and CO₂ utilization potential. However, their development is limited by the high decomposition energy barrier and slow reaction kinetics of the discharge product Li₂CO₃. In order to promote the development of high-performance Li-CO₂ batteries, researchers are committed to exploring cathode catalyst design strategies, aiming to improve catalyst performance and thereby enhance the reversibility and kinetics of the CO₂ reduction reaction and CO₂ evolution reaction. This paper reviews the latest research progress on transition metal-based catalysts for Li-CO₂ batteries and discusses how improving the activity of catalytic sites and increasing the density of catalytic sites through catalyst composition and structure design play a key role. On the one hand, through defect engineering, bimetallic, alloying, and heterogeneous interface construction, the activity of catalytic sites can be improved, the electronic properties of catalysts optimized, and the adsorption and activation capabilities for reactants and intermediates enhanced, thereby regulating the reaction pathway and inhibiting side reactions. On the other hand, with the help of porous structure design, single-atom catalysts, and crystal plane regulation, the density and utilization efficiency of active sites are significantly increased, mass transfer and charge transfer channels optimized, and the morphology distribution of discharge products improved. Future research should focus on elucidating the catalyst's influence mechanism on the battery reaction pathway, realizing pathway regulation, establishing theoretical foundations for the precise design of high-performance and highly reversible Li-CO₂ cathode catalysts, and promoting their practical application.

Abstract:Indium is a high-quality rare and precious metal element. When its purity reaches 99.999% (5N), it is referred to as high-purity indium. High-purity indium exhibits significantly superior performance, stability, and controllability compared to industrial-grade indium, making it highly valuable in advanced fields such as electronic chips and national defense. This paper provides a comprehensive review of various available technologies for the preparation and purification of high-purity indium, along with the latest research progress. The advantages and disadvantages of key methods, including solvent extraction, ion exchange, electrolysis, zone melting, distillation, and adsorption, are critically analyzed. Solvent extraction offers advantages such as energy efficiency and operational convenience, but it requires extensive use of organic solvents and acidic solutions, posing challenges in wastewater treatment and environmental pollution. Ion exchange is widely applied due to its reusability and ease of regeneration; however, its complex preparation technology, high equipment requirements, and elevated costs limit its broader adoption. Future reductions in production costs could significantly enhance its prospects. Electrolysis features simple equipment, environmentally friendly operation, and straightforward procedures, enabling both impurity separation and direct reduction of metal ions via electrons. Nevertheless, its long production cycles, high energy consumption, and the need for post-treatment of electrolyte waste remain drawbacks. Zone melting is highly efficient, energy-saving, and environmentally benign, with a simple and controllable process, yet it demands high-purity raw materials and exhibits limited effectiveness in purifying impurities with partition coefficients close to 1. Distillation is pollution-free and operationally simple but suffers from low efficiency, high equipment and energy costs, and potential generation of hazardous substances during high-temperature processes. Beyond improving existing technologies and optimizing core process parameters, future advancements in high-purity indium purification urgently require the integration of artificial intelligence and the exploration of industrialized pathways for advanced purification techniques.

Abstract:Solid oxide fuel cell (SOFC) is a emerging electricity generation technology with high efficiency and environmental friendliness. Planar anode-supported SOFC is one of the promising types of SOFC because of the low electrical resistance and flexible assembly. Modeling simulation can provide theoretical support and technical guidance for the development and optimization of the planar anode-supported SOFC. This paper focused on the planar anode-supported SOFC and presented a detailed discussion of both the geometric model and the single repeat unit (SRU) model. The geometric model enabled structural and property analyses of various typical planar anode-supported SOFC configurations, which was crucial for establishing a robust foundation for modeling research. The SRU model allowed for the simulation of individual cell structures and could be used to predict the performance of the entire stack based on the behavior of a single unit. However, most existing SRU models were based on idealized or simplified assumptions, and certain electrochemical reaction mechanisms remained poorly understood. Future modeling efforts should focus on multiphysics equations description, experimental data collection, and validation under real-world operating conditions in order to improve model accuracy and reliability.

Abstract:Iron minerals in red mud mainly exist in the form of hematite, limonite and goethite, and the iron recovery rate of direct magnetic separation is low, and it is difficult to obtain high-quality iron concentrate. The suspension magnetization roasting process has significant advantages in the extraction of iron ore resources. On the one hand, suspension roasting can ensure the reaction efficiency of fine-grained red mud；on the other hand, the flash magnetization roasting time is short, the magnetization effect is good, and the energy consumption is low. In this paper, the red mud (Fe₂O₃ 62.15 wt%) from an enterprise was used as raw material, and it was treated by flash magnetization roasting-low intensity magnetic separation process. The effects of process parameters on the iron separation effect were investigated, and the reconstruction behavior of the phase in red mud and the reaction mechanism of magnetization roasting were discussed by characterization analysis. Under the conditions of fluidization speed of 0.3m/s, temperature of 800℃, roasting time of 2.0min, CO concentration of 15%, grinding fineness of -0.032mm content of 72% and magnetic separation field strength of 0.25T, the yield of iron concentrate was 67.69%（TFe 56.21%）, the recovery rate was 87.45%, the tailings yield was 22.51%（TFe 24.26%）, which could be used to prepare cement. The results of characterization analysis show that the weak magnetic hematite (limonite) in the red mud is directional reduced into strong magnetic magnetite during the flash magnetization roasting process, and some diaspore, gibbsite and diaspore are dehydrated into Al₂O₃, while the gangue minerals such as quartz and rutile do not change. The main mechanism of magnetization roasting is that CO reacts with Fe³⁺ on the surface of hematite (limonite) to form Fe²⁺, and Fe²⁺ reacts with Fe³⁺ to form magnetite Fe₃O₄; the outer layer of Fe²⁺ and electrons diffuse to the inner layer of Fe₂O₃ through lattice vacancies; after lattice reconstruction, it is transformed into magnetite Fe₃O₄. The inner layer of O₂ diffuses to the outer layer and reacts with CO to form CO₂, which is continuously removed.

Abstract:At present, it is difficult to treat fine-grained low-gold and high-sulfur gold ores, silicate-coated gold ores and other refractory gold ores. In the literature, the pyrometallurgical smelting of copper-containing materials is mostly used, and the comprehensive recovery of valuable metals in the ore is realized by using the capture capacity of matte relative to precious metals, However, the actual production will be limited by the supply of copper smelting raw materials. Therefore, in this paper, a low-copper refractory gold mine abroad is used as the raw material, without adding copper-containing materials, and gold is captured by low-copper grade matte. The equilibrium separation relationship between FeS and Iron olivine slag was investigated by FactSage software, The effects of temperature and slag type on metal recovery rate were investigated by single factor test, and the following main conclusions were obtained. Factsage analysis shows that in the FeS-FeO-SiO₂ system at 1300℃, the two-phase separation of matte phase and iron-silicon slag can be achieved by controlling the type of smelting slag, even if the matte phase contains very low copper or does not contain copper. Under the conditions of temperature of 1300℃, holding time of 60min, Fe/SiO₂=1.3, CaO/SiO₂=0.2, the matte phase gold and copper grades were 34.4g/t and 2.98%, respectively, and the gold and copper recovery rates were 96.8% and 92.3%, respectively. In terms of phase composition, the matte phase is mainly composed of four phases: fayalite, magnetic iron, ferrous sulfide and polymetallic alloy. The associated elements such as arsenic, antimony and nickel in gold and ore are highly enriched in the alloy phase of copper matte.

Abstract:In the wet metallurgy process of rare earth elements, replacing traditional sulfonated kerosene with a new environmentally friendly diluent led to insufficient reducing capacity of the new diluent, causing Ce(Ⅲ) to oxidize into easily extractable Ce(Ⅳ). This cause excessive levels of the rare earth impurity Ce for a long time in the praseodymium-neodymium series products. Although H₂O₂ can reduce Ce (Ⅳ), there are a series of problems such as organic phase oxidation degradation, increased cost, and increased difficulty in wastewater treatment. This study proposes to replace H₂O₂ with hindered phenolic antioxidants to achieve green and efficient separation of rare earth elements by inhibiting the generation of Ce (Ⅳ) and reducing residual Ce (Ⅳ). The results showed that hindered phenols preferentially capture oxygen free radicals (HO·, ROO·) through hydroxyl hydrogen supply and steric hindrance effect, inhibit Ce (Ⅲ) oxidation, and efficiently reduce Ce (Ⅳ) in the organic phase to Ce (Ⅲ) (reduction efficiency ＞99.5%), achieving a synergistic effect of “oxidation inhibition and residual elimination”; When the amount of hindered phenol added is 1.0~2.0g/L and the temperature is 40~50℃, the generation rate of Ce (Ⅳ) decreases from 0.021g/(L·h) to 0.0023g/(L·h), and the inhibition time is greater than 120 hours. Industrial tests have shown that the Ce (Ⅳ) of organic phase has decreased from 0.05g/L to below 0.005g/L. The Ce impurity has remained stable at 200~400 ppm for a long time in praseodymium neodymium products, which meets the quality requirements of GB/T 20190—2023. Compared to H₂O₂ reduction, this technology reduces the consumption of reducing agents and avoids the risk of organic phase degradation caused by H₂O₂ decomposition. It provides technical support for the green and high-quality development of the rare earth industry and has significant industry promotion value.

Abstract:Jamesonite accounts for 30% to 40% of China s total antimony resources, making it a crucial mineral resource. Due to its high sulfur content, the sulfur-containing flue gas generated during smelting increases subsequent treatment costs. This paper proposes a low-temperature reduction smelting process for jamesonite to achieve sulfur fixation. Using ZnO as the sulfur fixative, carbon powder as the reducing agent, and Na₂CO₃ molten salt as the smelting medium, the study investigates sulfur fixation during the low-temperature reduction smelting of sulfur-bearing galena. Thermodynamic analysis indicates that both antimony sulfide and lead sulfide can undergo reduction reactions with zinc oxide and carbon powder at lower temperatures in a sodium carbonate system. During these reactions, Na₂CO₃ provides a liquid-phase reaction environment, optimizing the reaction pathway and enhancing reaction rates, thereby promoting more complete and thorough low-temperature sulfur fixation. Single-factor experiments demonstrate that under the following conditions: 1.224g of jamesonite, 7.5g of anhydrous sodium carbonate (reused in subsequent cycles), zinc oxide dosage at 1.25 times the theoretical amount, temperature of 900℃, and reaction time of 60minutes, the sulfur fixation rate reaches 97.2%, with lead and antimony recovery rates achieving 92.6% and 89.3%, respectively. TG and XRD analyses validated the thermodynamic analysis and experimental results, indicating that under optimal experimental conditions, the sulfur fixation rate reached its maximum. Sulfur in the minerals was solidified as ZnS and Na₂S, with significant amounts of lead-antimony alloy formed. SEM analysis revealed spherical particles of lead-antimony alloy in the product, columnar structures of PbO and Sb₂O₃, aggregated impurities such as sodium salts, and the presence of partial slag. This research provides theoretical support for low-temperature clean smelting of jamesonite.

Abstract:In view of the disadvantages of water quenching treatment of liquid phosphorus slag in industrial production of yellow phosphorus at present, the wind quenching method is used to treat liquid phosphorus slag and the numerical simulation of the wind quenching process is carried out. Based on the FLUENT simulation method, a finite element simulation model was established to simulate the process of liquid phosphorus slag treated by wind quenching technology, and the influencing factors of wind quenching process and the solidification heat transfer law of slag particles were analyzed. The results show that when the air velocity is relatively high, the diffusion speed of slag particles is fast, the temperature distribution in the granulation chamber is uniform, and the layout of the granulation chamber is more reasonably utilized. Moreover, the average outlet temperature is higher, the energy contained in the hot air is greater, and more energy can be utilized in the heat recovery stage. When the angle of the nozzle in the granulation chamber with the horizontal plane is 30°, the air quenching and granulation effect is better than that at 0°; when the angle is 60°, it is restricted by the structure of the granulation chamber, leading to slag particles flying out from the air outlet. The solidification process of liquid phosphorus slag droplets proceeds unevenly, and the thickness of the formed slag shell is also uneven. It provides a theoretical basis and guidance for optimizing the treatment of liquid phosphorus slag by air quenching and realizing the recovery of air quenching waste heat.

Abstract:In the process of electrodeposition, due to chlorine ions, sulphate radical ions, etc. in the electrodeposition, the traditional lead alloy anode is easily corroded, resulting in the thinning and perforation of the electrode plate, and the life-time is greatly shortened. Some literatures showed that titanium-based anode materials have greater strength and strong corrosion resistance, and the doping of graphite in the electrode can enhance the dense and hard characteristics, thereby improving its corrosion resistance and conductivity. This study proposes to prepare a new type of electrode material with titanium as the substrate, tin antimony metal oxide as the intermediate layer, and lead dioxide as the outermost active layer, and investigation the effect of graphite powder and fluorine doped in the lead dioxide layer on the electrochemical properties of anode. The results showed that doping C element makes the PbO2 layer more dense. When C=2g/L, the cell voltage in the electrolytic copper experiment reaches the minimum value of 2.137V, and its corrosion resistance is the best, and the sample failure time reaches 305min; after doping F element, the size of the electrode grain does not change much, and when the addition amount of F ion is 0.1g/L, the cell voltage in the electrolytic copper test reaches the minimum value of 2.016V, and the failure time is the longest; the effect of co-doping C and F is better than single-doping C and single-doping F, and the failure time reaches 337min. The cell voltage of the new electrode material prepared is 10.3% lower than that of the traditional Pb-Ca-Sn anode, and there is no need to clean the lead mud during use. The results can provide a reference for the goal of high current efficiency, good corrosion resistance and long life of the anode in the process of metal electrolys.

Abstract:Lithium iron phosphate batteries have a large market share in the new energy vehicle industry and the energy storage industry. The low cost of iron resources is benifit to reduce the production cost of lithium iron phosphate and maintains its market share. In this paper, high-value battery-grade iron phosphate products were prepared, using iron-containing solid waste from mines, by-product sulfuric acid and sulfur dioxide gas from smelters as raw materials, through a process route of reductive acid leaching-impurity removal-synthesis of iron phosphate. The effects of various process parameters were investigated, and lithium iron phosphate cathode materials were prepared and tested, using the synthesized iron phosphate sample. The following main conclusions were obtained: in the reductive acid leaching process, when the sulfuric acid concentration was 10g/L, the liquid-to-solid ratio was 4∶1 (L/kg), the temperature was 75℃, the amount of SO2 gas (flow rate 80mL/min) was twice the theoretical amount, and the reaction time was 30min, the iron concentration in the acid leaching solution was 29.3g/L, the utilization rate of sulfur dioxide was 45.72%, and the iron leaching rate reached 81.21%. Lime had a good effect on the removal of Al and Cu. When the pH value was neutralized to 5.0 with lime, the Al concentration decreased from 191mg/L to 3.79mg/L, and the Cu concentration decreased from 8.60mg/L to below the detection limit. Under the conditions of phosphoric acid concentration was 0.03mol/L and aging time was 2 hours, the iron-to-phosphorus ratio of iron phosphate was approximately 0.97, and the physical and chemical indicators met the HG/T 4701—2021 standard for battery-grade iron phosphate. The aging mechanism of amorphous iron phosphate was speculated: under the combined action of phosphoric acid and heating, amorphous iron phosphate gradually dissolved, and at the same time, a large amount of sulfate ions wrapped by iron phosphate were released into the solution, causing the concentrations of iron ions and phosphate ions in the slurry to gradually increase. After reaching supersaturation, small particles of FePO4·2H2O crystals would slowly recrystallize, and the crystallization process would adjust the iron-to-phosphorus ratio towards the theoretical value of 1∶1. The charg and discharg performance of the lithium iron phosphate cathode material was tested. The initial discharge specific capacity of lithium iron phosphate was 160.02mAh/g at 0.1C, and the initial coulomb efficiency was 99.42%. After 200 cycles at 1C rate, the discharge specific capacity reached 147.2mAh/g, and the capacity retention rate was 99.73%, indicating excellent cycling performance.

Abstract:Microwave heating has the advantages of fast heating speed, high efficiency and low energy consumption, but it also has the shortcomings of uneven temperature field. In this paper, the temperature field uniformity of microwave heating process is theoretically simulated by applying COMSOL simulation software, and on this basis, the role of microwave heating and induction heating on the preparation of TiB₂ powder by boro/carbothermal reduction method is compared with TiB₂ B4C and carbon black as raw materials. The paper shows that the uniformity of microwave heating can be significantly improved by the arrangement of “top corner arrangement” compared with “X-axis/Y-axis diagonal arrangement” and “diagonal arrangement”; furthermore, the heating uniformity of microwave heating can be significantly improved by the arrangement of “top corner arrangement” compared with “X-axis/Y-axis diagonal arrangement” and “diagonal arrangement”. In addition, the pure-phase TiB₂ powder with uniformly distributed grains can be obtained by microwave heating at 1350℃ for 20min. Compared with induction heating (complete reaction at 1550℃), microwave heating can significantly reduce the reaction temperature, which is mainly due to the non-thermal effect of microwave. At the same time, microwave heating can refine the grain size of TiB2 from 3.95μm to 1.93μm, and can avoid the phenomenon of grain agglomeration, which in turn improves the sinterability of powder and the density of sintered materials.

Abstract:The content of sodium are important indexes to evaluate the quality of potassium fluotitanate, potassium fluoroborate and potassium fluorozirconate. At present, there are no relevant standard methods for the analysis of sodium in potassium fluotitanate and potassium fluorozirconate. The determination method of sodium in potassium fluoroborate can no longer meet determination of sodium in potassium fluotitanate and potassium fluorozirconate. In order to solve this problem, this study carried out experiments of pretreatment of samples with various acids, and investigated the effects of titanium matrix and zirconium matrix on sodium determination. The results show that potassium fuotitanate, potassium fluoborate and potassium fluorozirconate samples can be completely dissolved by the method of “sulfuric acid dissolution+sulfuric acid smoking” to drive away fluorine. Under the selected conditions, titanium and zirconium matrix have no effect on the determination of sodium; Deionizing agents cesium chloride and strontium chloride are not needed in the determination process. The recovery rate of this method is between 84.0% and 113.9%, which is consistent with the determination results of inductively coupled plasma emission spectrometry. The relative standard deviation of this method is between 5.39% and 9.56%, which can meet the needs of rapid and accurate determination of sodium content in potassium fluotitanate, potassium fluoborate and potassium fluoacetate, and the determination range is 0.0050%~0.5000%. The study is an important supplement to the existing standards for the determination of sodium in fluoride salt.

Abstract:Aluminum dross is a solid waste produced in the electrolytic aluminum and recycled aluminum processes. Its main components are metallic aluminum, alumina, aluminum nitride and magnesia-aluminum spinel. By regulating the phase composition content of aluminum dross, magnesia-aluminum spinel materials can be prepared by solid-phase sintering. Rare earth oxides can promote the sintering densification and grain development and growth of magnesia-aluminum spinel materials. This study investigated the influence of trace doping of four rare earth oxides (Y₂O₃, Eu₂O₃, La₂O₃ and CeO₂) in the raw materials for preparing magnesia-aluminum spinel materials using aluminum ash slag on the performance of sintered materials. And the microscopic mechanism of rare earth oxides during the enhanced sintering process was explored, and the following main conclusions were obtained. The results show that Doping with four rare earth oxides (Y₂O₃, Eu₂O₃, La₂O₃ and CeO₂) can enhance the density performance of magnesium-aluminum spinel materials prepared by sintering aluminum ash. Magnesium-aluminum spinel materials were obtained by doping 3%Y₂O₃, 3%Eu₂O₃, 3%La₂O₃ and 3%CeO₂ in aluminum ash and sintering at 1673K for 3 hours. The volume density of the material changed from 2.02g/cm ³ to 2.04, 2.02, 2.13 and 2.07g/cm ³ respectively. The compactness effect of the sintered body strengthened by La₂O₃ doping was better than that of the other three types. During the doping and sintering process of rare earth oxides with large ionic radii, rare earth ions undergo solid solution diffusion. This diffusion process accelerates the elimination of pores, thereby promoting the sintering of spinel materials. The effect of different rare earth oxide doped aluminum ash slag on improving the density of magnesium-aluminum spinel materials prepared by sintering varies. Among them, the isomorphic displacement effect significantly enhances the density of the material. Aluminum-ash slag is a solid waste produced in the process of electrolytic aluminum and recycled aluminum. By regulating the phase composition of aluminum-ash slag, magnesia-aluminum spinel materials can be prepared by solid phase sintering. At the same time, the effect of doping modification of rare earth oxides on the density of materials is studied. The results show that doping of four kinds of rare earth oxides (Y₂O₃, Eu₂O₃, La₂O₃ and CeO₂) can improve the densification properties of MgAl₂O₄ spinel materials prepared by sintering of aluminum-ash slag. The bulk density of MgAl₂O₄ spinel was changed from 2.02g/cm³ to 2.04, 2.02, 2.13 and 2.07g/cm³ by sintering of 3%Y₂O₃, 3%Eu₂O₃, 3%La₂O₃ and 3%CeO₂ doped aluminum-ash slag at 1673K for 3h. La2O3 doping enhances the densification of sintered body better than other 3 types. Rare-earth oxide doping sintering with large ion radius makes rare-earth ion solid solution diffusion, diffusion accelerates the elimination of pores and promotes the sintering of spinel materials. Different rare-earth oxides doped alumina ash have different effects on the densification of MgAl₂O₄ spinel materials prepared by sintering, and the densification is stronger by isomorphic substitution.

Abstract:In response to the issue of value-added resource utilization of steel slag, this paper took low-iron electric furnace steel slag, high-density soil, and talc as raw materials, and Fe₂O₃ as additive, and prepared SiO₂-CaO-MgO(15%)-Al₂O₃ system ceramics under air atmosphere and N₂ atmosphere. It was focused on the iron distribution state and magnetic performance in this system, and examined the feasibility of using steel slag to prepare functional ceramics with soft magnetic characteristics, in order to avoid adding hard magnetic, Y-type ferrite, NiZnCu ferrite and other materials in the preparation process of soft magnetic ceramic materials, and to reduce the cost. The experimental results showed that using electric furnace steel slag, it was possible to prepare soft magnetic ceramics with a saturated magnetization intensity of 6.38 emu/g under the sintering conditions of N₂ atmosphere and 1150℃. There were three iron distribution states in the pyroxene system ceramics, the pyroxene phase with solid solution Fe²⁺, the magnetite and the hematite phase. The change process of iron element in the air sintering process was that the hematite had undergone decomposition reaction before 1150℃, and the part of magnetite generated in the range of 1150-1200℃ melted with the generated pyroxene, which promoted densification of the ceramics, and the decomposition reaction ended at 1200℃, and the hematite was converted into the magnetite phase with magnetic. Some of the test samples showed hematite after sintering, which was due to the oxidation of magnetite generated at high temperature during the cooling of the test sample in air atmosphere. The magnetic properties of the samples sintered in N₂ atmosphere were significantly better than those sintered in air atmosphere, and the magnetic properties were positively correlated with the content of theite phase in the samples. The magnetic properties parameters of the test sample sintered at 1150℃ in N₂ atmosphere optimal, with Ms and Mr of 6.38emu/g and 1.38emu/g, respectively. There was a certain gap between the Ms value of the samples prepared in this study and of the plasma sintered MnZn ferrite laminated composite ceramics (33.05emu/g), but the results could provide reference for subsequent preparation of soft magnetic ceramic materials from steel slag.

Abstract:The gas-liquid flow and oxygen content in the pressurized leaching stirred tank to some extent restrict the reaction efficiency inside the tank. Currently, the research on related literature is relatively scarce. In this paper, a mathematical model of gas-liquid flow in the stirred tank is constructed based on Fluent, and the influence of sulfuric acid concentration, baffle, intake velocity and bubble diameter on the gas-liquid flow inside the tank is explored by means of CFD simulation technology. The results show that when the concentration of sulfuric acid rises from 0g/L to 60g/L, the flow rate in the reactor slows down and the stirring area becomes smaller. However, when the oxygen content in the reactor rises from 0.1944% to 0.2017% and the concentration increases from 60g/L to 180g/L, there is little change. The installation of baffles will convert the tangential velocity inside the reactor into radial and axial velocities, suppress the swirling phenomenon, increase the distribution of turbulent kinetic energy inside the reactor to promote stirring and mixing. The gas holdup increases by 2%, but the stirring power inside the reactor increases by 1.2%. Increasing the air intake velocity will significantly increase the gas content in the reactor. When the air intake velocity changes from 0.15m/s to 0.25m/s and 0.35m/s, the oxygen content increases from 0.61% to 1.04% and 1.53% respectively. Increasing the diameter of the intake air bubbles slightly reduces the gas holdup in the reactor. When the diameter of the intake air bubbles changes from 0.001m to 0.004m and 0.005m, the gas holdup decreases from 1.005% to 0.996% and 0.985% respectively.

Abstract:Vacuum induction melting and atomization technology (VIGA) is currently the mainstream technology for preparing high-performance spherical metal powders, but there is still a lack of systematic research on the process parameters of atomization Laval nozzles. This article designs an atomized Laval nozzle and uses CFD simulation to simulate the effects of atomization pressure, airflow injection angle, and guide pipe extension length on the atomization flow field structure, velocity distribution, and static pressure inside the guide pipe. The results indicate that an increase in atomization pressure can expand the shock wave region, and both the flow field velocity and the static pressure inside the guide tube increase; An increase in the angle of airflow injection can cause the stagnation point and Mach disk position to shift upward; The elongation of the extended length of the guide pipe causes a phenomenon of static pressure first decreasing and then increasing. Based on the above analysis, the optimal process parameters are determined as follows: air jet angle of 30° and guide pipe extension length of -2mm. And 316L stainless steel powder was prepared under an atomization pressure of 3MPa. The powder has a uniform particle size distribution, high sphericity, and an alloy powder collection rate of ≥90%, significantly improving the atomization efficiency and powder quality of VIGA technology.