The rapid development of the aluminum industry has led to a stockpile of red mud exceeding 1.5 billion tons, yet its comprehensive utilization rate remains below 12%. This massive accumulation not only occupies substantial land resources but also causes environmental pollution and resource waste. This review first systematically outlines the sources, distribution, and environmental hazards of red mud, and analyzes its characteristics in terms of chemical and mineral compositions. It then summarizes the current status and developmental trends in red mud treatment and comprehensive utilization, with a focus on reviewing research progress in its applications, such as in building materials, metal recovery, and environmental remediation. Finally, future prospects are discussed. The paper highlights the need to strengthen technological innovation to address the challenges of high alkalinity and heavy metal stability. It proposes achieving efficient resource utilization of red mud through the co-processing of multi-source solid wastes and the tiered utilization of all its components. Emphasis is also placed on demonstrating practical projects, improving the standard system for various application fields, and leveraging market drivers to promote the large-scale and high-value utilization of red mud resources.

Hydrogen energy, as a critical component of future energy systems, necessitates efficient transportation methods to facilitate global energy transition. Pipeline transportation has emerged as the preferred solution for long-distance hydrogen delivery due to its safety and economic advantages. However, hydrogen embrittlement in pipeline steels remains a primary safety concern, involving multi-scale mechanisms spanning hydrogen atom behavior and dislocation movement that challenge comprehensive characterization. This review summarizes predominant hydrogen embrittlement mechanisms in hydrogen pipelines, including hydrogen-enhanced decohesion, hydrogen-enhanced localized plasticity, and hydrogen adsorption-induced dislocation emission, with emphasis on their synergistic interactions. Key influencing factors of hydrogen embrittlement are discussed in terms of chemical composition, microstructure, precipitated phases, inclusions and segregation. Meanwhile, a multi-dimensional characterization method, ranging from macroscopic mechanical testing to microstructure characterization, is summarized for the cross-scale behavior of hydrogen in the steel of hydrogen transmission pipelines. Addressing energy transition imperatives, enhancing hydrogen embrittlement resistance has become pivotal for scaled hydrogen transportation. Innovative approaches integrating machine learning and cross-scale modeling are introduced for anti-hydrogen embrittlement material design, demonstrating how inverse design strategies accelerate development of high-strength hydrogen embrittlement-resistant pipeline steels. Finally, combined with the current research status of hydrogen pipeline steels, the key points and prospects for future research on hydrogen pipeline steels are summarized.

This paper reviews the superior properties of high-purity copper (with a purity of 5N or higher) compared to conventional 3N or 4N copper, particularly in terms of thermal conductivity, electrical conductivity, and fatigue resistance. It also summarizes the extensive applications of high-purity copper in fields such as semiconductors, display panels, photovoltaics, defense, advanced manufacturing, and aerospace. Additionally, the research progress of various preparation methods, including electrolysis, zone refining, vacuum distillation, vacuum induction melting-directional solidification, vacuum ion beam melting-directional solidification, and anion exchange, are discussed. The paper proposes that a combined wet and pyrometallurgical process, such as electrolytic refining integrated with zone refining or vacuum distillation, represents one of the key future directions for the preparation of high-purity copper materials. Furthermore, it emphasizes the importance of completely eliminating all potential contamination sources throughout the entire production process as a critical research focus for advancing high-purity copper refining technology. Looking ahead, as the performance requirements for high-purity copper continue to increase and its application fields expand, preparation technologies are expected to evolve toward greater efficiency, eco-friendliness, and cost-effectiveness to meet growing market demands.

Foamed slag technology is the core process of ultra-high-power electric furnace steelmaking, which is crucial for enhancing thermal efficiency, protecting furnace lining and optimizing molten steel quality. It takes biomass charcoal as the research object, systematically analyzed its performance and influencing factors as a blowing agent, and compares it with traditional fossil-based blowing agents (coke, graphite, anthracite). Waste wood block charcoal, corn stover charcoal, waste bamboo charcoal and industrial wood charcoal were used in the experiment, combined with chemically formulated electric furnace slag, and their foaming ability was evaluated by high-temperature foaming experiments with comprehensive foaming index (K). The results showed that the waste wood charcoal showed the best overall performance due to its high fixed carbon and low ash. The corn stover charcoal significantly reduced the viscosity of the slag due to its high ash content and high alkali metal content, resulting in the worst foaming area and duration. The waste bamboo charcoal, although with the highest fixed carbon, had a high potassium content in the ash content that exacerbated the deterioration of the foam stability, and had a second best overall performance than that of the waste wood charcoal. Compared with fossil blowing agents, graphite showed the highest maximum foaming area and comprehensive foaming index, but industrial wood charcoal showed substitution potential by virtue of its longer foaming time and low-carbon environmental protection characteristics. The synergistic effects of slag alkalinity, viscosity and surface tension on foaming performance were further revealed. It was pointed out that alkali metals (e.g., K, Na) in the ash fraction of biomass char reduced the viscosity by disrupting the silica-oxygen network, but an excessive amount shortened the foam life. This study meets the development needs of green metallurgy under the "double carbon" strategy, and provides a theoretical basis for the large-scale application of biomass carbon in electric furnace steelmaking.

The iron and steel industry is one of the major source of carbon emissions, and advancing pellet technology is one of the effective measures to achieve the "dual-carbon" goals. Excessive reduction swelling of pellets can degrade reactor permeability and even leads to production accidents. This paper systematically reviews the primary mechanisms of reduction swelling in iron ore pellets, including lattice expansion from phase transformations, iron layer cracking due to gas pressure, structural damage induced by carbon deposition, cracking resulting from uneven reduction stresses, and the precipitation morphology of nascent iron. Studies have shown that regulating the formation of iron whiskers is a key breakthrough in inhibiting malignant expansion, while reduction swelling is significantly influenced by preheating/roasting parameters, porosity, gangue composition, and reduction conditions. Key measures to suppress pellet swelling involve optimizing ore blending, rational control of basicity, refining preheating/roasting processes, and restricting harmful element intake. It provides a theoretical foundations and technical pathways for optimizing pellet performance and advancing low-carbon ironmaking technologies.

As CO₂ emissions from pre-iron processes account for over 70% of the total emissions in the iron and steel industry, carbon reduction in pre-iron processes is crucial for achieving the industry′s "carbon peak" and "carbon neutrality" goals. An overview of development status of existing hydrogen metallurgy technology is summarized, followed by a description of the pure hydrogen shaft furnace reduction process route proposed by CISRI (China Iron and Steel Research Institute Group). Through the development of pure hydrogen shaft furnace reduction technology and core equipment, CISRI established the first industrial demonstration line for pure hydrogen shaft furnace reduction in the world. Through optimization of process parameters and continuous hydrogen supply, a metallization rate of 97.0%-99.4% was achieved. Melting tests of carbon-free sponge iron from the pure hydrogen shaft furnace were conducted using well-chamber furnace, electric arc furnace, and vacuum induction furnace. Results show that the melting cycle for cold-pressed balls and blocks is shorter in the electric arc furnace, while gas content decreases significantly in the vacuum induction furnace. The high-purity iron obtained by vacuum induction furnace exhibits a purity (mass fraction) of 99.9%. The pure hydrogen metallurgy technology developed by CISRI offers a solution for achieving low or zero CO₂ emissions in green hydrogen metallurgy in China. Hydrogen metallurgy is anticipated to exhibit greater competitiveness than carbon metallurgy in the future.

Zinc, as an important strategic metal, is widely used in different fields. The leaching slag produced by its smelting contains silver, zinc, iron, germanium and gallium, which has high comprehensive utilization value. Therefore, the zinc smelting process is introduced in detail, and the advantages and disadvantages of flat-tank zinc smelting, vertical tank zinc smelting, closed blast furnace zinc smelting, electric furnace zinc smelting, and conventional leaching, hot acid leaching and oxygen pressure leaching in wet process are compared. The reaction principle and its application in industrial production are revealed. At the same time, the recovery process of valuable metals such as silver, zinc, iron, germanium and gallium in zinc smelting is described in depth, and the recovery effect of flotation, pyrometallurgy, hydrometallurgy and combined processes is compared. The advantages and disadvantages of different recovery processes are analyzed from the point of view of principle, as well as the status quo in industrial application. In addition, the application progress of zinc leaching slag in building materials, mine filling materials, geopolymers, etc., and the research direction of improving the comprehensive utilization of zinc smelting slag in the future are also discussed.

High strength low alloy (HSLA) steel is widely used in building and bridge construction, oil and gas pipelines, ships, and offshore platforms due to its excellent comprehensive properties and cost advantages. The yield ratio serves as a key indicator in the development and application of HSLA steel. This review first summarizes the yield ratio of single-phase steels, such as ferritic, pearlitic, and martensitic steels, as well as ferrite/austenite multi-phase steels, at different strength levels. In general, steels with higher yield strength exhibit higher yield ratio. The introduction of ferrite or austenite phases in steel is beneficial for reducing the yield ratio. Subsequently, recent advances in the design of multi-phase microstructure and the control of rolling and heat treatment processes for high-strength steels with low yield ratio are discussed. Finally, progress in the use of machine learning and artificial intelligence for assisting the study of mechanical properties of HSLA steels is introduced. Achieving a favorable combination of low yield ratio, high toughness, and high plasticity is a development trend in HSLA steel. Constructing multi-phase, metastable, multi-scale, and multi-morphological microstructures provides an effective approach for developing high-strength, high-toughness, and low yield ratio steels. And the integration of physical metallurgy and data science is becoming a key pathway for precise microstructure design of such steel grades.

To systematically investigate the influence of mass fraction of Y₂O₃ and w(CaO)/w(Al₂O₃) on the physicochemical properties of the CaF₂-CaO-Al₂O₃-MgO-Y₂O₃ slag systems, this study addresses the severe burning loss of the Y element during the electro-slag remelting process of Y-containing rare earth steels. It proposes improving slag system performance by adding Y₂O₃ and adjusting the w(CaO)/w(Al₂O₃), thereby increasing the yield of Y. Experiments were conducted to prepare five slag systems with different mass fractions of Y₂O₃ and four slag systems with different w(CaO)/w(Al₂O₃) values. Various testing and analytical methods were comprehensively utilized, including an X-ray diffractometer, an X-ray fluorescence spectrometer, hemispherical melting temperature testing, rotating cylinder viscosity measurement, a Fourier transform infrared spectrometer, and a scanning electron microscope, to conduct a systematic study on the phase composition and content, melting characteristics, viscosity changes, structural features, and precipitated phase characteristics of the slag system. The aim is to provide theoretical support for optimizing slag composition, suppressing the burning loss of the Y element, and improving its yield. The results indicate that the addition of Y₂O₃ promotes the formation of the CaYAlO₄ phase. As the mass fraction of Y₂O₃ increased from 0 to 20%, the melting temperature of the slag first decreased and then increased, while the viscosity first increased and then decreased, with the optimal Y₂O₃ mass fraction of 15%. With the increase of the w(CaO)/w(Al₂O₃) from 0.8 to 1.4, the characteristic peaks of the CaYAlO₄ phase in the slag systems gradually intensified, the melting temperature and viscosity of the slag systems decreased, and the proportion of needle-like CaYAlO₄ in the slag systems increased. The decrease in viscosity might be primarily attributed to the depolymerization of[AlO_nF_4-n]^- tetrahedral complexes and the transformation of[AlO₄]^5- tetrahedra into[AlO₆]^9- octahedra induced by the elevated w(CaO)/w(Al₂O₃). The low viscosity led to the reduction of ionic clusters migration resistance, which in turn reduced the energy potential barrier for nucleation and crystal growth, accounting for the increase in the percentage of CaYAlO₄. The needle-like morphology of CaYAlO₄ may be affected by the growth mechanism controlled by screw dislocations. Based on the above discussion, the optimal slag composition is determined as follows, Y₂O₃mass fraction of 15%, w(CaO)/w(Al₂O₃) is 1.4. The melting temperature of this slag ratio is 1 346 ℃, and its viscosity at 1 600 ℃ is 0.28 Pa·s.

Platinum group metals (PGMs) play a vital role in the automotive, petrochemical and electronic devices industries due to their unique physical properties and excellent catalytic activity, rendering them indispensable strategic resources for the country. However, China's PGM mineral resources are scarce with low ore grades and high mining costs. Consequently, recovering PGMs from secondary resources, particularly the large quantities of spent PGM catalysts has become the primary source of these metals. Based on the operating conditions, current PGM enrichment processes can be divided into pyrometallurgical and hydrometallurgical processes. Pyrometallurgical processes feature high processing capacity and short process flows, making them suitable for large-scale operations, but they are energy-intensive and cause considerable environmental pollution. In contrast, hydrometallurgical processes operate under milder reaction conditions and good selectivity for specific materials, though they involve longer process flows and high reagent consumption. After enrichment, PGMs in the solution require purification and refining. The precipitation method is applicable for enriching solutions with high metal ion concentrations but tends to introduce impurities. Solvent extraction yields high-purity products, yet the extractants are often toxic and volatile which increases operational difficulty. Ion exchange achieves high separation efficiency and low pollution, but it is costly and severely restricted by the solution system. This paper summarizes common enrichment processes and conducts detailed analysis of their respective advantages and disadvantages. It also overviews different purification processes and elaborates on their merits and demerits. On this basis, the paper outlines future research directions for PGM recovery from spent catalysts, providing new insights for promoting efficient recycling of secondary PGM resources and developing economical, environmentally friendly, and intelligent recovery processes.

With the development of the electronic information industry and the intelligent revolution, China′s electronics sector has imposed increasingly stringent demands on the quality and supply of semiconductor raw materials. In the semiconductor industry, copper—particularly high-purity copper—demonstrates significant market potential due to its excellent physical and chemical properties, such as high electromigration resistance, electrical conductivity, thermal conductivity, ductility, low dielectric constant, and corrosion resistance. However, the quality and quantity of its production have consistently fallen short of industry requirements. Hydrometallurgy is the main process for preparing electrolytic copper, which is used for the production of high-purity copper. It enjoys advantages such as simple preparation method, mature process, low production cost, and low energy consumption, and thus dominates the high-purity copper production industry. However, during the process of preparing high-purity electrolytic copper, the differences in the preparation techniques and parameter control result in significant fluctuations in the quality of high-purity electrolytic copper. This paper discusses different electrolytic copper production routes, provides a detailed analysis of the advantages, disadvantages, and implementation cases of various production processes, and summarizes the strengths and challenges of ultra-high-purity metal preparation methods. Finally, based on the current status of production and demand for high-purity electrolytic copper in China, a forward-looking perspective is presented. Accelerating the industrial production and construction of high-purity electrolytic copper will be Accelerating the industrial-scale production and construction of high-purity electrolytic copper will be further conducive to accelerating the localization process of high-purity electrolytic copper needed for the development of China′s semiconductor industry and solving the problem of China′s reliance on imported raw materials in high-end, precision and cutting-edge fields.

Driven by the "dual carbon" strategic objectives, the iron and steel industry, as a major carbon emission sector, underwent technological innovations in low-carbon ironmaking that became crucial pathways for achieving carbon neutrality. This led to the development of several key technologies including fluxed pellet production with large pellet ratio blast furnace operation, composite iron coke, hydrogen-enriched carbon cycling blast furnace, and hydrogen-based shaft furnace short process. The application of fluxed pellets and high pellet ratio in blast furnace optimized the burden structure by partially replacing sinter. Composite iron coke served as highly reactive material that substituted for conventional coke. The core principle of hydrogen-enriched blast furnace technology involved injecting hydrogen or hydrogen-rich reducing gas through tuyeres to replace carbon-based fuels. Hydrogen-based shaft furnace short process emerged as an alternative ironmaking process that utilized hydrogen as reducing agent, demonstrating advantages in efficiency, environmental friendliness and energy conservation. All the aforementioned low-carbon ironmaking processes demonstrated carbon emission reduction potential. A systematic investigation of low-carbon ironmaking technology systems was required, involving both the advancement of traditional blast furnace processes and the development of alternative ironmaking technologies. The selection of appropriate low-carbon technological pathways was projected to contribute significantly to achieving carbon neutrality in China′s steel industry.

High-strength automotive beam steel serves as a critical component for supporting vehicle mass and external loads, requiring high strength, high toughness, and excellent cold formability. However, hard inclusions such as Al₂O₃, magnesium-aluminum spinel, and calcium aluminate present in the steel do not readily deform during rolling. Improper control will damage product performance. Cerium (Ce) plays a role in modifying inclusions and refining grain structure in steel. It can transform Al₂O₃, Mg-Al-O and Ca-Al-O inclusions into rare-earth inclusions such as CeAlO₃ and Ce₂O₂S. These cerium-containing inclusions can act as nucleation sites, refining the solidification structure of the steel. Through melting and casting experiments using a high-temperature tube furnace, combined with scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and thermodynamic calculations, the effects of different Ce content on inclusion modification and as-cast structure refinement in high-strength beam steel were systematically studied. The results show that as the Ce content in the steel increases, the inclusion modification sequence follows CeAl₁₁O₁₈→CeAlO₃→Ce₂O₃→Ce₂O₂S→CeS, with the final modified product depending on the Ce content. When the mass fraction of Ce is 0.005 5%, the modified inclusions are Ce-Al-O types, exhibiting polygonal or (near-)spherical morphologies due to genetic effects and modification-induced spheroidization. When the mass fraction of Ce reaches 0.018 0%, the inclusions are further modified into Ce-O-S types with spherical morphologies, showing characteristics of aggregation and growth, while the originally angular Mg-Al(-Ti)-O inclusions disappear. Ce effectively reduces the average size of inclusions and decreases the number of large-sized inclusions. As the Ce content increases, the number of inclusions first decreases and then increases, with the smallest average size and lowest quantity observed at a Ce mass fraction of 0.005 5%. Additionally, Ce exhibits a grain-refining effect in steel. Both Ce-Al-O and Ce-O-S inclusions promote solidification nucleation, with the most significant refinement of the as-cast microstructure achieved at a Ce mass fraction of 0.018 0%. Thermodynamic calculations further elucidate the formation mechanisms of the relevant inclusions.

To address the issue that the excessive strength of hot-rolled ultra-low carbon steel sheets is detrimental to subsequent cold rolling and forming, deformation in the austenite-ferrite two-phase zone can be applied to reduce strength, but this significantly increases deformation resistance during hot rolling. Therefore, compression deformation of low-carbon steel in the austenite-ferrite two-phase region (773-845 ℃) was conducted using a Gleeble-1500 thermomechanical simulator. Optical microscopy (OM), scanning electron microscopy (SEM), and electron backscatter diffraction (EBSD) were employed to investigate the effects of different deformation temperatures and strains on peak stress and microstructure, aiming to obtain process parameters that reduce deformation resistance in the two-phase zone and to analyze the corresponding softening mechanisms. The results show that the microstructure of the steel after two-phase zone deformation consists of ferrite and pearlite. Under a constant strain rate of 1 s^-1, strains of 30% or 60%, and deformation temperatures ranging from 775 ℃ to 825 ℃, dynamic recrystallization is difficult to occur when the specimen is deformed at a low temperature of 775 ℃ with a small strain of 30%. During deformation, the microstructure is dominated by coarse grains that have only undergone recovery and growth. Under these conditions, the ferrite grain size reaches a maximum of 55.4 μm, and the deformation resistance is minimized at 103 MPa. The primary mechanism for the reduction in deformation resistance in the two-phase zone under these process parameters is grain coarsening. Investigating the influence of deformation process parameters in the two-phase zone on the deformation resistance of low-carbon steel is of significant importance for achieving precise control of deformation resistance in industrial production and effectively reducing the strength of hot-rolled plates.

As the dominant process in the zinc industry, the hydrometallurgical production system generates cobalt-bearing supernatant solution and cobalt residues with considerable resource value during operation. Efficient recovery and utilization of these by-products can promote solid waste resource utilization and alleviate China's shortage of cobalt resources. This paper provides an in-depth analysis of cobalt removal technologies from zinc sulfate leaching solutions, systematically comparing the principles, efficiency, cost effectiveness, and environmental impact of various methods, including zinc dust cementation (activated by arsenic/antimony salts), organic reagent-based cobalt removal, and redox precipitation for cobalt removal. Furthermore, a comprehensive review is conducted on the treatment of cobalt residues through leaching followed by multi-metal ion separation, summarizing the technical advantages and drawbacks of different leaching approaches (selective leaching, acid leaching, alkali leaching, and combined leaching) and separation techniques (oxidation precipitation, chemical precipitation, solvent extraction, ion exchange, and membrane electrolysis). A case study from the zinc smelting plant of Baohui Group is presented to trace the migration and transformation behavior of cobalt throughout the entire process, including oxidative roasting, acid leaching, three-stage purification, and cobalt residue treatment. Zinc hydrometallurgical plants should design suitable technical routes based on process technology, production costs, energy conservation, and environmental sustainability. This entails optimizing leaching and separation parameters, developing novel cobalt removal agents, establishing cobalt-zinc co-production systems, and enhancing the economic benefits of cobalt recovery while ensuring electrolytic zinc quality.

Sintering optimization ore blending is a critical step in steelmaking production, aiming to achieve efficient resource utilization, cost control, and optimized smelting performance through multi-mineral blending. This process plays a significant role in improving resource utilization rates, enhancing sinter quality, and reducing production costs and energy consumption. However, with the increasing scarcity of high-quality iron ore resources and the growing complexity of raw material structures, traditional blending methods, which rely on static linear models and empirical decision-making, struggle to address challenges such as ore composition fluctuations, multi-objective optimization, dynamic coupling of multi-processes, and nonlinear constraints. This is particularly evident when attempting to simultaneously optimize chemical composition, cost, and metallurgical performance. Intelligent algorithms, such as genetic algorithms and particle swarm optimization, by integrating data-driven approaches with mechanistic models, can significantly enhance multi-objective optimization capabilities, providing new pathways to overcome the bottleneck of dynamic multi-objective optimization. The research progress in sintering optimization ore blending is systematically reviewed, the applicability of traditional methods and intelligent algorithms is compared, and the technical directions for constructing an intelligent low-carbon blending system are proposed, addressing core issues such as dynamic responses, cross-process coordination, and data-mechanism fusion. The goal is to provide theoretical support and practical reference for the steel industry in achieving resource-intensive utilization and intelligent transformation.

Copper, as a foundational material for the global transition to new energy industries, is facing increasing demand. The rapid development of the copper industry is accompanied by substantial consumption of minerals, energy, and water resources, while also generating significant volumes of wastewater and other pollutants, imposing severe environmental pressure. Water serves as both a critical resource and an essential medium in metallurgical processes, with its consumption directly linked to wastewater generation. Therefore, this study takes a typical pyrometallurgical copper smelting enterprise as a case to systematically analyze the characteristics of water metabolism throughout the entire process, identify key water-saving stages, propose water network optimization strategies, and promote the green transformation and sustainable development of the copper industry. Using material flow analysis, the study quantifies the relationships among water consumption, wastewater discharge, and recycling from a holistic process perspective. It integrates all water-use processes into a water balance system, establishes an optimization model and evaluation index system for the water network of the copper smelting enterprise, and proposes a hierarchical water-use strategy based on a "graded treatment-cascading utilization-closed-loop reuse" framework. The results show that after optimization, the enterprise's fresh water consumption decreased from 15.74 m³/t to 12.51 m³/t, a reduction of 20.52%. The recycled water usage increased from 949.67 m³/t to 1 274.54 m³/t, a rise of 34.21%. Water resource efficiency improved by 68.04%, the water recycling rate increased from 98.2% to 98.7%, system reclaimed water usage rose from 1.30 m³/t to 4.05 m³/t, and wastewater discharge decreased from 5.05 m³/t to 4.43 m³/t. This study reveals the characteristics of water flow in copper smelting processes, proposes hierarchical water-use strategies and water network optimization methods, providing a feasible technical pathway for efficient water resource management and near-zero discharge. Future work could further integrate intelligent monitoring and control technologies to achieve dynamic optimization and refined management of water systems.

In response to the issues caused by reduced supply of high sulfur low silicon ore powder on the Shougang pellet production line consisting of a grate-rotary kiln-annular cooler, including insufficient sulfur source for the acid production system, decreased magnesium to aluminum ratio in the blast furnace, and deteriorated slag fluidity, a systematic study was conducted on the feasibility of using highsulfur boron-containing iron powder (HSBC, containing B₂O₃ 5%, MgO 10.18%, S 1.0% by mass) to replace Peruvian fines in the production of acid pellets. The phase composition microstructure and thermal decomposition characteristics of HSBC were characterized using a combination of X ray diffraction reference intensity ratio (XRD-RIR), scanning electron microscope energy dispersive spectroscopy (SEM-EDS), and thermogravimetric analysis differential scanning calorimetry (TG-DSC) method. Five gradient tests with HSBC mass ratios of 0, 2%, 4%, 6%, and 8% were designed and implemented on an industrial 10 kg scale disc pelletizer grate machine rotary kiln and annular cooler line for green pellet preparation, basket roasting and sampling detection. The results show that HSBC particles have a rough surface and a fibrous structure. Their particle size is relatively coarse with 72.6% below 74 μm complementing the extremely fine Macheng powder in particle size distribution. This complementarity increased the drop strength of green pellets from 6.2 times to 8.5 times. TG-DSC analysis revealed an exothermic peak at 379 ℃ corresponding to the conversion of Fe₃O₄ to Fe₂O₃ and an endothermic peak between 661.7 and 916 ℃ associated with sulfide oxidation dolomite decomposition and ludwigite lattice reconstruction with a total weight gain of 2.9%. The roasted pellets exhibited a core shell structure characterized by a liquid phase shell and a porous core with porosity increasing from 17.7% to 25.9%. As the HSBC mass ratio increased from 0 to 8%, pellet reducibility decreased from 58.50% to 50.32% while reduction swelling increased from 10.98% to 22.34%. The compressive strength after one hour of reduction improved by 169 N and the softening temperature interval Δt widened from 91 ℃ to 115 ℃. Considering metallurgical performance indicators and blast furnace adaptability, the optimal HSBC addition ratio is determined to be 5%. At this ratio, the compressive strength of the finished pellets reached 3 173 N, the desulfurization rate is 91.5% and the sulfur input is 1 117 mg/m³, which is close to the baseline level. Additionally the pellets demonstrated good reducibility at 55.02% and a controllable reduction swelling rate of 16.36%. The research findings provide a theoretical basis and technical support for the large scale application of high-sulfur boron-containing iron powder in pellet production.

With the advancement of green and low-carbon transformation in the steel industry, the demand for comprehensive utilization of solid wastes in the metallurgical sector continues to grow. Carbide slag, a high-calcium solid waste generated by the chemical industry, not only occupies land resources but also poses environmental risks due to its large-scale accumulation. As a high-calcium solid waste, carbide slag holds significant potential for replacing conventional calcium-based fluxes in iron ore sintering. This study aimed to systematically investigate the feasibility of using carbide slag as a substitute for conventional fluxes in iron ore sintering and its impact mechanism on the sintering and mineralization processes. Mineralogical analyses of carbide slag, limestone, and quicklime were conducted using XRF, XRD, laser particle size analyzer and thermogravimetric analyzer. The results indicate that compared to conventional fluxes, carbide slag exhibits higher CaO content, finer particle size, lower thermal decomposition temperature and higher thermal stability, demonstrating its suitability as a sintering flux. Through fundamental sintering characteristic tests and micro-sintering experiments, combined with the mineralogical properties of carbide slag, the effects of its substitution for conventional fluxes on sintering characteristics and the mineral phase structure of sinter were systematically analyzed. The results show that as the substitution ratio of carbide slag increases from 0 to 60%, the assimilation temperature decreases, while the fluidity of the liquid phase, the strength of the binding phase and the formation capacity of calcium ferrite improve, promoting the development of an interwoven-corroded structure. However, when the substitution ratio exceeds 60%, although the assimilation temperature continues to decrease, the fluidity of the liquid phase and the formation capacity of calcium ferrite decline, accompanied by an increase in silicate minerals and porosity, leading to a deterioration in the mineral phase structure of the sinter. At a substitution ratio of 60%, the sinter exhibits a uniform mineral phase structure, the highest content of calcium ferrite, predominantly in acicular and columnar forms. The findings of this study provide new insights into the resource utilization of carbide slag and the cost reduction and efficiency improvement in sinter production.

This study investigated the effects of rare earth(RE) and magnesium treatments on non-metallic inclusions in ultra-high purity (UHP) 316L austenitic stainless steel, aiming to enhance steel cleanliness to meet the stringent requirements for semiconductor equipment materials. Traditional aluminum deoxidation processes produce alumina, which is prone to shedding during service and contaminates the entire semiconductor processing system. Although rare earth and magnesium are considered potential alternative deoxidizers, systematic studies on their combined treatment process, particularly the influence of addition sequence on inclusions in UHP 316L stainless steel, remain insufficient. Using a VIM+VAR duplex process, three deoxidation routes were designed, RE (Y) treatment only, Mg-Ce sequential treatment, and Ce-Mg sequential treatment. The effects of each process, under industrial production conditions on the size, distribution, type, and rating of inclusions were systematically examined. Inclusion characteristics and their evolution at various processing stages were evaluated using metallographic microscopy, SEM-EDS, and Thermo-Calc thermodynamic simulations. The results demonstrate that in VIM+VAR smelting of UHP 316L stainless steel, the Ce-Mg sequential deoxidation sequence is the most effective strategy for high-level inclusion control. This approach results in the lowest inclusion distribution density and smallest average equivalent diameter in VIM+VAR samples, with no large inclusions (≥8 μm) observed. The fine Type D inclusion rating is below 0.5, meeting industry standards for UHP 316L stainless steel. In contrast, the Mg-Ce treatment shows poor inclusion control due to severe premature magnesium loss, which limits effective synergy with rare earth. The proper RE-Mg addition sequence fully utilizes the strong deoxidation capability of rare earth elements and the bubble flotation and stirring effects of magnesium vapor, providing a key process route for achieving high cleanliness control in UHP 316L stainless steel.

By adopting an appropriate alloy preparation method and element doping to regulate the composition and microstructure of alloy ingots, metal materials can be modified, which is an important means to address the problems of Sm element volatilization, poor preparation stability, and difficult microstructure control in SmFe₁₂-based rare earth alloys. Based on experimental phenomena, it was determined that induction melting method was more suitable for the preparation of SmFe₁₂-based rare earth alloy ingots than arc melting method. Zr, Co, Cu and Ti were doped into SmFe₁₂ alloy ingots, and the doped ingots were subjected to homogenization heat treatment at 1 100 ℃ for 36 h. The phase composition and microstructure were characterized and analyzed using XRD and SEM. The mechanism of the effect of element doping on the alloy phase composition was studied. The effect of element doping was analyzed from the perspective of thermodynamic parameters such as mixing enthalpy, mixing entropy, Gibbs free energy and atomic size difference. Combined with the experimental results and thermodynamic analysis, the problems of poor stability and difficult preparation of SmFe₁₂ alloy ingots have been addressed by element doping. Under the action of interatomic forces, Sm_0.8 Zr_0.2 Fe_8.5 Co₂ Cu_0.5 Ti alloy is composed of SmFe₁₁ Ti phase, SmCu₅ phase and α-Fe phase. Zr and Ti atoms exist in the form of solid solution in the SmFe₁₁ Ti phase, and the solid solubility of Zr and Ti is higher in the SmFe₁₁ Ti phase around the α-Fe phase. Under the attractive force of Cu atoms on Sm atoms and the repulsive force of Cu atoms on Fe atoms and Co atoms, Cu atoms are precipitated to form SmCu₅ phase, which promotes the decomposition of SmFe₁₁ Ti phase and leads to the decrease in SmFe₁₁ Ti phase content and the increase in α-Fe phase content. The results show that, the doping of Zr, Co, Cu and Ti elements improves the stability of the SmFe₁₂-based alloy's main phase while precipitating the SmCu₅ phase, which is expected to further optimize the magnetic properties of the SmFe₁₂-based alloys. High-quality raw materials are provided for future powder preparation, and control of the grain size and distribution of SmCu₅ phase becomes a new research direction.