- 百种中国杰出学术期刊
- 中国精品科技期刊
- “中国科技期刊卓越行动计划二期”领军期刊
- 入选“中国精品科技期刊顶尖学术论文(F5000)”
- 入选《科技期刊世界影响力指数(WJCI) 报告》
- EI、CA、JST收录期刊
- 中国金属学会会刊
- 中文核心期刊
- 中国科技核心期刊
- 中国科学引文数据库(CSCD)来源期刊
Strip rolling has reached a high level of online detection and automation control capabilities. However, as the proportion of high-end products continues to rise and the demand for the coordinated optimization of multiple indicators such as quality, cost, and energy consumption increases, traditional mechanistic modeling approaches and single-process, single-task rolling process control strategies are insufficient to meet the evolving technological needs of strip rolling. Digital modeling methods and intelligent control technologies, focusing on multi-field, multi-scale, multi-process, and multi-task applications, have rapidly advanced in addressing core quality indicators, including dimensions, performance, and surface quality, as well as production and operational metrics such as efficiency, cost, and energy consumption. The acquisition, feature extraction, and fusion of multi-source heterogeneous data in the rolling process are critical prerequisites for enabling intelligent control. Process determination and anomaly diagnosis have evolved from traditional threshold-based approaches to more comprehensive decision-making and root cause inference, thus raising the bar for the interpretability, traceability, and reusability of diagnostic conclusions. Optimization control, by contrast, needs to achieve multi-objective optimality through coordinated regulation of multiple actuators under equipment capability and process window constraints. Accordingly, with "data acquisition and fusion-quality prediction modeling-quality anomaly diagnosis-multi-objective collaborative optimization" as the overarching thread, this paper systematically reviews recent advances and industrial practices in strip rolling, covering digital modeling, process monitoring and diagnostic decision-making, and optimization control, thereby providing a rigorous reference for the development of intelligent rolling technologies.
To address global climate change and achieve the nation's "dual carbon" goals, the steel industry, a key carbon-emitting sector, is in urgent need of a clean energy transition. Hydrogen-based direct reduction ironmaking technology, which replaces coke with green hydrogen, is recognized as a pathway to carbon-neutral iron production. However, the reduction of iron oxides by hydrogen is a strongly endothermic reaction whose kinetic rate is significantly influenced by temperature. Preheating hydrogen to above 1 000 ℃ is a core step to enhance reaction efficiency and reduce energy consumption per ton of steel. This paper focuses on the electric heating hydrogen preheating system for hydrogen-based vertical furnaces, systematically reviews the technical characteristics and application status of mainstream heating methods, and deeply analyzes the research progress in multiphysics coupling numerical simulation techniques for hydrogen heating processes. Existing gas electric heating simulation technologies achieve precise control of the heating process, optimize flow and heat transfer, and predict thermal stresses and hydrogen embrittlement risks through collaborative modeling of electromagnetic-thermal-fluid-structure fields, which have become key tools for design optimization. However, current technologies still face challenges such as multi-field coupling convergence, dynamic modeling of high-temperature hydrogen embrittlement, multi-scale mesh generation, and adaptability to green electricity fluctuations. Future efforts should focus on addressing the core challenges of multi-physics coupling in high-temperature electric heating, combining numerical modeling with experimental validation to improve simulation accuracy and computational efficiency. Simultaneously, the deep integration between simulation and process systems must be strengthened to realize the synergistic optimization of heating processes with hydrogen production and metallurgical operations, as well as the dynamic adaptation to green electricity fluctuations. This will establish an efficient design framework of "high-fidelity simulation-experimental calibration-process integration", providing core technological support for the clean energy transition of the steel industry and the commercial application of hydrogen energy.
Steel slag is a bulk solid waste produced in the steelmaking process with a huge output but low comprehensive utilization rate leading to great resource waste and environmental pollution. With the widespread attention to steel slag recovery and the innovative development of related technologies, researchers have carried out extensive studies on the separation, recovery, high-value and green utilization of valuable elements in steel slag and remarkable progress has been achieved in both theoretical research and related process technologies. This paper sorts out the research achievement on the extraction and separation of phosphorus and iron from steel slag at home and abroad in recent years. Firstly, it introduces the occurrence form and distribution characteristics of phosphorus and iron in steel slag, reviews the research status of the separation, extraction and reuse of phosphorus and iron from converter steel slag, analyzes the principles, characteristics and application scope of different technologies, discusses the influence of technical parameters such as temperature and steel slag particle size on the separation and recovery effect, and indentifies the key problems restricting the popularization and application of various technologies. The extraction methods of phosphorus from steel slag are mainly divided into chemical leaching, physical separation (magnetic separation, flotation) and biological leaching. The extraction methods of iron are divided into magnetic separation method and reduction method. Through the summary and comparison of recycling technologies, recovery efficiency, cost control and pollution control are the core problems restricting the resource recovery of phosphorus and iron from steel slag at present. Finally, the future development direction of related technologies is prospected, which provides theoretical and technical reference for the full recovery and high-value utilization of steel slag and promotes the high-quality and sustainable development of the iron and steel industry.
In the steel industry, the ironmaking process involves complex and high-risk environments with extreme temperatures and high pressures, exposing frontline workers to high safety risks for long time. Against the background of smart manufacturing and industrial digital transformation, building an intelligent safety monitoring system for the ironmaking process has become one of the core paths for the high-quality development of the industry. This paper systematically reviews the evolution of ironmaking safety monitoring from mandatory management to intelligent early warning, and analyzes the research progress and application practices of three core dimensions including personnel, equipment and process based on the "Human-Machine-Material-Environment-Process" framework. Significant breakthroughs have been made in multi-source information perception, intelligent risk identification and cross-system coordinated early warning. Personnel safety can realize quantitative early warning of typical risks such as irregular operation and on-the-job fatigue through the integration of heterogeneous positioning, visual recognition and physiological state monitoring. Equipment safety initially constructs a full-life-cycle fault prediction and health management (PHM) system for key equipment based on multi-source state perception and hybrid intelligent models; process safety significantly extends the early warning window for abnormal furnace conditions by means of global perception and data fusion technologies, and some systems have realized cross-process coordinated control. Combined with the engineering practices of enterprises such as Wuhan Iron and Steel Co., Ltd. and Liuzhou Iron and Steel Co., Ltd., the intelligent safety monitoring system has achieved quantifiable benefits in reducing blast furnace downtime, improving labor productivity and optimizing energy consumption. However, it still faces bottlenecks in large-scale deployment, such as data silos, insufficient model generalization ability, high construction and operation costs, shortage of interdisciplinary talents and lack of unified standards. For the future, to build an intrinsically safe, intelligent and efficient ironmaking production environment, it is necessary to further develop hybrid-driven models embedded with metallurgical mechanisms to improve model interpretability and working condition adaptability. At the same time, a safety-oriented unified data platform should be built to break information barriers and support cross-system coordinated early warning and regulation.
Accurate regulation of the micro-differential pressure at converter mouth is crucial for improving converter gas recovery efficiency and realizing the green and low-carbon transformation of steel industry. To address the problems of response lag and insufficient stability in traditional proportional-integral-derivative control(PID)caused by transient strong disturbances such as oxygen valve switching and auxiliary material charging during the blowing process, this paper systematically summarizes the research progress of micro-differential pressure control models and classifies and evaluates the construction methods and application effects of models including fuzzy logic, artificial neural networks, Particle Swarm Optimization (PSO) and mechanism-data dual-driven models. Comparative analysis shows that existing technologies have difficulty balancing the requirements of high control precision and fast real-time response. Traditional PID control responds quickly but lacks working condition adaptability. Single intelligent algorithms represented by neural networks significantly improve the nonlinear fitting accuracy but suffer from dynamic response lag due to excessive computational load. Mechanism-data dual-driven models enhance their adaptability in complex scenarios by introducing physical constraints yet still face technical challenges such as difficult dynamic identification of model parameters, a sharp increase in system complexity and delay in underlying data transmission. This paper further conducts an in-depth analysis of the essential differences in control logic between the oxygen converter gas recovery(OG) and converter gas dry purification and recovery system (LT) and reveals the severe nonlinear regulation challenges of the LT caused by drastic flue gas temperature changes, electro-thermal-mechanical multi-physics coupling interference and actuator inertia lag. Based on this, it is proposed that future research should focus on developing adaptive fault-tolerant algorithms and constructing a digital twin sensing systems to achieve accurate characterization of the full-process dynamic characteristics and break through the control bottlenecks in the LT. This paper prospects the development trend of micro-differential pressure control models and point out that efforts should be made to improve the mechanistic interpretability of deep learning models, enhance multi-objective co-evolution capability and promote in-depth algorithm integration, which will provide solid theoretical support and technical guidance for the intelligent and green operation of the entire converter steelmaking process.
In response to the urgent need for the green transformation of iron and steel industry under the "dual carbon" strategy, gas-based shaft furnace direct reduction technology has emerged as a critical development direction due to its significant carbon reduction potential. The preparation of high-grade direct reduction (DR) pellets represents a core link of this technology. Current research mainly focuses on magnetite pellets while systematic studies on hematite-based pellets especially those prepared by mixing magnetite and hematite have remained relatively insufficient. This study took high-grade hematite (H ore) and magnetite (M ore) as raw materials and systematically explored the preparation process of direct reduction pellets suitable for the production requirements of gas-based shaft furnaces. Four magnetite-hematite blending schemes (B1, B2, B3, B4) were designed.Through systematic pelletizing and roasting experiments, the thermal regime for oxidized pellets preparation was optimized. The results demonstrate that under the appropriate thermal regime, all blending schemes can produce high-quality oxidized pellets with a basicity of 0.3, which are characterized by a compressive strength higher than 2 800 N per pellet, a total iron grade (mass fraction) of over 67.5%, and low contents of harmful elements. Simulated metallurgical performance tests based on the Midrex process show that the reduction index of all blended oxidized pellets reaches 85%-90%, the reduction swelling index is all below 11%, the low-temperature reduction degradation index is less than 2.5%, and the metallization rate exceeds 93%, with all indicators meeting the technical requirements of the Midrex gas-based shaft furnace direct reduction process. This study confirms the feasibility of preparing high-grade DR pellets from magnetite-hematite blends. It not only enriches the raw material system for DR pellet production, but also provides important technical support for reducing the raw material cost of gas-based shaft furnaces and expanding the supply channels of high-quality pellet ore resources. It has positive significance for promoting the large-scale application of gas-based shaft furnace direct reduction technology.
To address the problem of surface peeling defects in 022Cr18Ti ultra-pure ferritic stainless steel hot-rolled pickled strips, the causes of the defects were investigated and process optimization measures were proposed. The 3.5 mm×1 245 mm steel strips with peeling defects were used as test materials. The macroscopic morphology, microstructure and composition characteristics of the defects were systematically analyzed by optical microscopy, stereomicroscopy, field emission scanning electron microscopy and energy dispersive spectrometry. The results show that the surface peeling defects of the steel strips are divided into linear and spindle-shaped types. The linear peeling defects are mainly distributed in the 1/4 or 3/4 width area of the steel strip, and the spindle-shaped peeling defects are characterized by severe damage at both ends and slight concave pits in the middle. The core cause of the linear peeling defects is slag entrainment in the continuous casting mold, and the abnormal H2S content in the coke oven gas in the heating furnace causes sulfur segregation and high-temperature corrosion, which further aggravates the defect development. The spindle-shaped peeling defects are jointly induced by insufficiently modified Al2O3 inclusions and TiN and its composite inclusions precipitated during the casting process. Both types of inclusions cause microcracks in the matrix during rolling and expand continuously, eventually leading to the stripping of the surface metal. In response to the causes of the defects, targeted process optimization schemes were proposed for the refining, continuous casting and heating processes, controlling w([Ca])/w([Al])≥0.15 in the LF furnace and w([N])≤0.010% in molten steel, optimizing the structure of the continuous casting nozzle and using special mold powder, and controlling the H2S mass concentration in the coke oven gas below 30 mg/m3. After process optimization, the occurrence rate of peeling defects in 022Cr18Ti hot-rolled pickled steel strips decreases from 0.67% to 0.29%, which effectively improves the surface quality of the product and production efficiency, and provides a technical reference for the prevention and control of similar defects in ultra-pure ferritic stainless steel.
In order to investigate the influence of hot rolling reduction on the microstructural evolution throughout the entire processing route and the final mechanical and magnetic properties of non-oriented electrical steel produced by twin-roll strip-casting technology, a twin-roll strip-casting non-oriented electrical steel with a designed composition of Fe-3.35Si-1.37Mn(mass fraction, %)was used as the research object. Single-pass hot rolling tests with different reductions were carried out. Subsequently, all samples were uniformly cold-rolled to 0.27 mm to ensure the same total rolling reduction and then subjected to decarburization annealing to complete the preparation of finished products. The mechanical and magnetic properties of the finished products were tested. The results show columnar grains inclined and fractured in the central region during hot rolling. With the increase of hot rolling reduction, the fraction of columnar grains decreases gradually until they are completely transformed into equiaxed grains. A further increase in hot rolling reduction leads to a gradual increase in the amount of fibrous microstructures and a continuous rise in the fraction of {111} oriented texture which exerts a deteriorating effect on the subsequent magnetic properties. With the increase of hot rolling reduction, the cold rolling reduction decreases correspondingly, the cold rolling deformation stored energy decreases significantly, the driving force for annealing recrystallization is weakened and abnormal grain growth is caused. Under the condition of the same total rolling reduction, the higher the annealing temperature, the smaller the influence of stored energy differences of grains with different orientations on the growth process of recrystallized grains and the more uniform the grain size distribution. With the increase of hot rolling reduction, the magnetic induction (B50) shows a gradually decreasing trend, the low frequency core losses(P1.5/50) and medium frequency core losses(P1.0/400) increase gradually, and the yield strength and tensile strength show a trend of first increasing and then decreasing. Under the laboratory conditions of this study, the non-oriented electrical steel with both excellent magnetic properties and good mechanical properties can be prepared when the hot rolling reduction is 25.0%-37.5%, the cold rolling reduction is 80% and the annealing system is 1 100 ℃ for 2 min. This study clarifies the influence law of hot rolling reduction on the full-process microstructure inheritance and property regulation of cast-rolled silicon steel in the "hot rolling-cold rolling-annealing" process under the same total rolling reduction and provides a theoretical basis and process window for the production of sub-0.30 mm high-grade non-oriented electrical steel by twin-roll strip-casting technology.
00Cr12Ni10MoTi steel is extensively utilized in critical applications such as aerospace, energy and power systems, and high-end bearing manufacturing owing to its superior strength, hardness, corrosion resistance, and high-temperature performance. Nitrogen and oxygen contents exert a significant influence on the quantity, size, morphology, and distribution of non-metallic inclusions, which in turn dominate the mechanical properties of the material. In this study, thermodynamic analysis was performed on the performed of typical inclusions in 00Cr12Ni10MoTi steel. The results show that the actual solubility product of Al2O3 is larger than its equilibrium solubility product at 1 873 K enabling preferential precipitation in molten steel with a higher precipitation tendency in high nitrogenoxygen steel. In contrast, the actual solubility products of TiN and AlN are both smaller than their equilibrium solubility products, so they cannot precipitate at this temperature. Combined with Thermo-Calc simulation results, TiN mainly precipitates at the final stage of solidification and its mass fraction peaks at approximately 1 150 K, which is consistent with the thermodynamic analysis. Microstructural observation and analysis of inclusions in 00Cr12Ni10MoTi steel were carried out using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS) and electron backscatter diffraction (EBSD). It is found that the density, average size and area fraction of inclusions in high nitrogenoxygen steel are higher than those in low nitrogenoxygen steel, and the average grain size of high nitrogenoxygen steel is 7.9 μm which is 9.5% finer than that of low nitrogen-oxygen steel. Mechanical property tests indicate that the yield strength, tensile strength and impact energy of low nitrogenoxygen steel are 655 MPa, 918 MPa and 163 J, respectively, while those of the high nitrogen-oxygen steel reach 718 MPa, 961 MPa, and 165.5 J, respectively. Owing to the synergistic strengthening effect of dispersion strengthening by nitrogen-oxides and grain refinement strengthening by nitrogen, the mechanical properties of high nitrogen-oxygen steel are significantly better than those of low nitrogenoxygen steel. This study reveals the influence law of nitrogen and oxygen contents on inclusions and mechanical properties of 00Cr12Ni10MoTi steel, providing a theoretical basis for the stable production of highstrength and hightoughness martensitic stainless steel.
To investigate the effect of magnesium on the properties of FH420 offshore engineering steel, two groups of experimental FH420 steels, with and without magnesium treatment, were smelted in a 25 kg vacuum induction furnace, followed by the application of identical temperature-controlled rolling and cooling processes. Thermodynamic calculations on the evolution of inclusions were performed via FactSage software, while the composition, size and number density of inclusions were statistically characterized using a scanning electron microscope, an energy dispersive spectrometer and an automatic inclusion analysis system. Meanwhile, mechanical properties were evaluated through room-temperature tensile tests and Charpy impact tests at -60 ℃. In addition, electron backscatter diffraction technology was adopted to analyze the matrix microstructure, effective grain size, as well as the micro-strain and crack propagation path beneath the impact fracture surface by means of IPF, KAM and GOS analysis. The results show that after the addition of 0.001 2% magnesium, the main oxide inclusions in the steel are transformed from Ti-Al-O system to Ti-Al-Mg-O system, with the inclusions significantly refined, the average size is reduced from 2.47 μm to 1.82 μm, and the number density of inclusions is increased from 54.01 mm-2 to 71.85 mm-2. After magnesium treatment, the microstructure of the steel is converted from coarse polygonal ferrite to fine interwoven acicular ferrite, and the effective grain size is decreased from 6.31 μm to 4.93 μm. Magnesium treatment exerts a slight influence on the yield strength, but the impact absorption energy at -60 ℃ is increased from 173 J to 234 J, with both the crack initiation energy and propagation energy improved remarkably. These results indicate that magnesium treatment can effectively induce the formation of acicular ferrite through modifying and refining inclusions in the steel, thereby refining the effective fracture unit of the steel. On the one hand, it enhances the capacity of the matrix to participate in plastic deformation; on the other hand, it forces the cleavage cracks to change directions frequently during propagation, thus consuming more fracture energy and improving the impact toughness of the steel. The effect of magnesium treatment on the properties of FH420 steel is systematically studied herein, which provides guidance for the research and development of new-generation products and the optimization of industrial processes for high-strength low-alloy offshore engineering steels serving in extremely cold environments.
To clarify the influence law of of rare earth yttrium(Y) on the inclusions and microstructural properties of pearlitic rail steel, pearlitic rail steel samples with and without rare earth Y addition were taken as the research objects, and the variation laws of inclusions, microstructure, and mechanical properties were systematically analyzed. The results indicated that the addition of rare earth Y refines the average size of MnS inclusions from 9.3 μm to 4.6 μm under 1 000× field of view and reduces the number density from one per three fields of view to one per ten fields of view. It also reduces the average size of TiN inclusions from 4.1 μm to 2.1 μm and decreases the number density from one per three fields of view to one per six fields of view. Al2O3 inclusions with an average size 6.7 μm(one per five fields of view) and Al2O3-MnS composite inclusions with an average size of 11.7 μm(one per eight fields of view) in the original steel are not detected. Instead, spherical Y-based oxides and oxysulfides with an average size of 1.3 μm and two per field of view are found in the steel. The addition of rare earth Y refines the average interlamellar spacing of pearlite from 0.202 μm to 0.162 μm, reduces the average size of pearlite colonies from 12.63 μm to 9.13 μm, and increases the fraction of high-angle grain boundaries from 18.6% to 22.6%. The tensile strength, yield strength, elongation after fracture, reduction of area and room temperature impact energy of the test steel with rare earth Y addition reach 1 248.7 MPa, 837.3 MPa, 15.8%, 41.3% and 15.0 J respectively. They are increased by 7.2%, 10.9%, 4.80%, 4.84% and 53.3% compared with the test steel without rare earth Y addition. The refinement of pearlite interlamellar spacing is the main reason for the improvement of strength and plasticity of the test steel while the reduction of pearlite colony size significantly promotes the improvement of steel toughness.
Steel slag tailings, generated as a major solid waste during iron and steelmaking, are characterized by complex mineralogy and poor phase stability, which has resulted in persistently low resource utilization efficiency. To address the limitations of conventional leaching methods, including poor selectivity, low leaching efficiency, and restricted product utilization, this paper proposes an ammonium chloride-hydrochloric acid (NH4Cl-HCl) synergistic leaching process, utilizing the high selectivity of ammonium salt leaching and the high leaching rate of hydrochloric acid leaching to achieve efficient extraction of calcium (Ca) and magnesium (Mg) while effectively suppressing iron (Fe) dissolution from steel slag tailings. The effects of hydrochloric acid concentration, ammonium chloride concentration, steel slag tailings particle size, leaching temperature, leaching time, and liquid-to-solid ratio on the leaching behaviors of Ca, Mg, and Fe were systematically investigated. Phase transformation and microstructural evolution during leaching were analyzed using X-ray diffraction (XRD) and scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS). The results indicate that under the conditions of HCl concentration of 0.35 mol/L, NH4Cl concentration of 2 mol/L, steel slag tailings with particle size less than 75 μm (200 mesh) accounting for approximately 45%, leaching temperature of 60 ℃, leaching time of 30 min, and liquid-to-solid ratio of 25.0 mL/g, the leaching efficiencies of Ca and Mg reached 61.20% and 20.75%, respectively, while the Fe leaching efficiency was limited to only 1.45%. Mechanistic analysis reveals that NH4Cl alone can dissolve most of the active Ca and Mg bearing minerals in steel slag tailings, whereas the introduction of HCl further promotes the decomposition of calcium-magnesium silicate minerals. Meanwhile, the NH4Cl-HCl synergistic system regulates the solution pH and induces hydrolysis and precipitation of iron species, resulting in preferential enrichment of iron in the leaching residue. SEM-EDS observations show that the leached slag surface exhibits pronounced porous corrosion features, with preferential dissolution of active calcium silicate minerals, while iron-bearing phases such as RO solid solutions and Ca2(Fe, Al)2O5 remain largely undissolved. The research results provide both theoretical insight and practical guidance for the efficient separation and recovery of Ca, Mg, and Fe from steel slag tailings, and offer a promising technical route for the low-carbon and high-value utilization of steel slag tailings.
Aiming at the challenge of simultaneously enhancing the strength and corrosion resistance of 2195 Al-Li alloy through traditional aging treatment, this study aims to explore the regulatory effects of the coupled process of pre-deformation and non-isothermal aging on its microstructure, mechanical properties and corrosion behavior so as to seek an efficient heat treatment scheme with excellent comprehensive performance. Solution-treated 2195 Al-Li alloy samples were subjected to pre-deformations of 4%, 8% and 10% followed by non-isothermal aging treatment heating at a rate of 20 ℃/h to 200 ℃ and then cooling at a rate of 40 ℃/h to 100 ℃. Tensile tests, scanning electron microscopy (SEM) and optical microscopy were used to systematically analyze the mechanical properties, fracture morphology, precipitate characteristics and intergranular corrosion behavior of the alloy under different processing conditions. The results show that pre-deformation significantly promotes the fine and dense precipitation of T1 phase (Al2CuLi). All alloys reach the peak strength when cooled to 160 ℃. The 10% pre-deformed sample has the highest yield strength 535 MPa while the 8% pre-deformed sample has the best comprehensive performance with the maximum strength-ductility product. Microstructural analysis shows that the 8% pre-deformed sample has the narrowest precipitate-free zone PFZ at grain boundaries and its fracture surface presents a large number of dimples and tear ridges showing transgranular ductile fracture. Non-isothermal aging treatment also significantly improves corrosion resistance. The intergranular corrosion depth of the 8% pre-deformed sample is only 36.7 μm which is about 60% lower than that of the traditional peak-aged state 91.8 μm.This result is attributed to its fine T1 phase and narrow PFZ. The coupled treatment of pre-deformation and non-isothermal aging can synergistically optimize the strength, ductility and corrosion resistance of 2195 Al-Li alloy. Among the tested conditions 8% is the optimal pre-deformation amount. This process not only greatly shortens the aging time of peak strength from 16 h to 6 h with an efficiency improvement of 62.5% but also achieves excellent comprehensive performance matching by refining intragranular precipitates and narrowing grain boundary PFZ providing an important basis for the development of heat treatment processes for aerospace components.
During the slow cooling process of copper slag in the ladle, the cooling rate of copper slag in the liquid-solid phase transition temperature range is one of the key factors affecting the subsequent flotation. To analyze the liquid-solid phase transition behavior characteristics of copper slag at different positions in the slag ladle under the existing slow cooling system, this paper took a 12 m3 cast steel slag ladle from a certain factory as the research object, constructed a three-dimensional unsteady numerical heat transfer model based on the finite volume method, simulated and analyzed the liquid phase cooling rate and crust formation law of copper slag under the existing slow cooling system, and further explored the influence of air cooling duration change on the slow cooling process. The results show that during the slow cooling process of copper slag, affected by the combined action of the thermal resistance of the formed slag crust and the release of latent heat of liquid-solid phase transition, the internal cooling rate presents significant spatial inhomogeneity. The liquid phase cooling rate of copper slag near the inner wall of the slag ladle is relatively fast, which mainly occurs in the first 3 h of air cooling, and its volume accounts for less than 1/3; the cooling rate of the remaining areas is significantly lower, generally below 1 K/min. With the extension of air cooling duration, the copper slag crust continues to thicken; after 12 h of air cooling, the crust thickness increases by about 20 mm for every additional 2 h, which effectively reduces the "explosion" risk when copper slag is transferred to the water cooling stage. However, with the continuous thickening of the crust, its thermal resistance is further enhanced, which makes the promotion effect of the water cooling stage on the internal cooling rate of copper slag limited, and on the contrary, prolongs the time required for the complete solidification of copper slag. The research results can provide a theoretical reference for the optimization of the slow cooling system of copper slag ladles and the improvement of slag ladle structure and materials.
Hydrogen production via the hydrolysis of bulk active aluminum alloys presents distinct advantages, such as low water quality requirements, on-site hydrogen generation, and on-demand supply. This method effectively addresses critical challenges in hydrogen production, storage, transportation and safety, establishing it as a promising candidate for hydrogen supply in fuel cell applications. However, the high cost of gallium (Ga), a key component in active aluminum alloys, remains a major bottleneck restricting its large-scale deployment and application in the hydrogen energy field. Therefore, achieving reduced Ga consumption and efficient recycling represents an essential pathway to promote the development of such materials toward low-cost, eco-friendly and industrial application. Based on E-pH (Pourbaix) diagram analysis of the Al-Ga-Mg-Sn quaternary system, this study systematically investigated the leaching performance in acidic (pH < 2) and alkaline (pH>12) systems for solid residues generated from hydrolytic hydrogen production. Utilizing the differences in dissolution behaviors of Al and Ga between acidic and alkaline environment, an acid/alkali leaching process was developed to realize solid-liquid separation and one-step recovery of elemental Ga. The effects of leaching agent type and concentration, temperature, and solid-to-liquid ratio on Ga recovery efficiency were explored, and solid-to-liquid ratio on Ga recovery efficiency were explored, and the essential differences in Ga recovery mechanisms between acidic and alkaline systems were revealed. The results indicate that in HCl acidic system, Ga is easily oxidized to ionic state and enters the solution, making the recovery of elemental Ga difficult. In contrast, NaOH exhibits superior leaching performance compared to KOH in alkaline systems. A maximum Ga recovery efficiency of 26% is achieved under the conditions of 90 ℃, 0.4 mol/L NaOH, and a solid-to-liquid ratio of 1 g∶40 mL. Increasing the temperature can significantly improve the Ga recovery efficiency. The difference in recovery efficiency between acidic and alkaline systems stems from the distinct corrosion behaviors of the solid residue. HCl induces localized pitting corrosion, resulting in Ga being trapped in the residue pores and difficult to leach out, whereas NaOH promotes uniform corrosion, which facilitates the precipitation and aggregation of Ga. The One-step acid/alkali leaching process enables the on-site recovery of elemental Ga, eliminating the multi-step separation and enrichment procedures involved in conventional "ionic dissolution-secondary conversion" processes and thus greatly simplifying the process flow.
The FeO-SiO2-Al2O3-CaO system is a common slag type in the matte smelting of copper concentrate and the reduction smelting of tin concentrate. The transport properties of the melt have a crucial influence on chemical reaction kinetics, slag-metal separation efficiency, and the content of valuable metals in the slag. In this paper, a comparative study on the local structure and transport properties of copper slag and tin slag melts in the FeO-SiO2-Al2O3-CaO system was carried out using molecular dynamics (MD) simulation, aiming to reveal the essential mechanism for the different effects of CaO and FeO contents on the transport properties of the melts. The results show that[SiO4]4- tetrahedra and[AlO4]5- tetrahedra are the main structural units of the network skeleton, and[SiO4]4- tetrahedra are more stable than[AlO4]5- tetrahedra. In the copper slag system, as the mass fraction of CaO increases from 3% to 18%, non-bridging oxygen and free oxygen transform into bridging oxygen, structure unit Q0、Q1 and Q2 transform into Q3 and Q4, the degree of structural complexity (DSC) and degree of polymerization (DOP) of the system increase, and the viscosity increases from 0.21 Pa·s to 0.30 Pa·s. In the tin slag system, as the mass fraction of FeO increases from 3% to 18%, bridging oxygen transforms into non-bridging oxygen and free oxygen, Q3 and Q4 transform into Q0、Q1 and Q2, the DSC and DOP of the system decrease, and the viscosity decreases from 0.66 Pa·s to 0.37 Pa·s. At the same content of CaO in copper slag and FeO in tin slag, the DSC and DOP values of copper slag are lower than those of tin slag, and the viscosity of copper slag is also lower than that of tin slag. Fe2+ and Ca2+ act as both network modifiers and charge balancers in the system; the network modification ability of Fe2+ is stronger than that of Ca2+, while the charge compensation ability of Ca2+ is stronger than that of Fe2+. The efficiency of FeO to reduce the viscosity is about three times that of CaO. The results provide a theoretical and technical basis for the efficient utilization of copper and tin resources.
Against the backdrop of "carbon neutrality", carbon reduction in the long-process steel production route based on blast furnace-converter (BF-BOF) has become a hot research topic in the iron and steel industry. The operational efficiency of ferrous material flow at the interfaces between ironmaking, steelmaking and rolling processes exerts an important influence on carbon reduction of the long-process steel production route, and interface technology has become one of the key research directions for carbon reduction in the long process. Taking the ironmaking-steelmaking interface based on torpedo ladle-hot metal ladle in a domestic steel plant as the research object, this paper constructed a simulation model for material flow operation at the ironmaking-steelmaking interface using Python tool, and systematically studied the influence of production organization modes such as torpedo ladle allocation under blast furnaces on the operational efficiency of material flow at the ironmaking-steelmaking interface, with torpedo ladle turnover rate, empty ladle time during turnover and total waiting time as evaluation indicators. The results show that the commissioning mode and operation mode of torpedo ladles have the most significant influence on the operational efficiency of material flow at the ironmaking-steelmaking interface; reducing the number of online turnover torpedo ladles from 18 to 17 increases the turnover rate by 3.0%-6.5%; compared with the turbulent flow operation mode, the torpedo ladle turnover rate is increased by about 20% under the laminar flow operation mode where 3 blast furnaces correspond to 5 converters at the ironmaking-steelmaking interface; under the "17+1" commissioning mode of torpedo ladles, reducing the number of torpedo ladles allocated under blast furnaces by 1 within the range of 6-10, increasing the ratio of "one torpedo ladle for one transfer" by 10% within the range of 80%-100%, and increasing the ratio of "one torpedo ladle to one hot metal ladle" by 10% within the range of 60%-100% improve the torpedo ladle turnover rate by 4.6%, 2.3% and 1.6% respectively. After optimizing the production organization mode of the studied ironmaking-steelmaking interface, the torpedo ladle turnover rate is increased from 5.2 times/d to 6.6 times/d, the temperature drop in the process from blast furnace tapping to hot metal entering the desulfurization station is reduced by 11 ℃, and the carbon emission(CO2) per ton of steel in the whole process is reduced by about 3.3 kg. The research results can provide a reference for improving the operational efficiency of ironmaking-steelmaking interfaces in other domestic enterprises of the same type.
Frequent tube bursting in the high-temperature superheater of dry coke quenching (CDQ) boilers is a primary constraint on their long-term safe operation. This failure involves complex interactions between multiple factors, namely erosion and corrosion, and existing research lacks quantitative elucidation of their synergistic coupling mechanism. This study aims to reveal this coupled failure mechanism and propose effective integrated protection strategies. A multidisciplinary approach combining field case statistics, computational fluid dynamics (CFD) simulation, and microscopic material analysis was adopted. First, operational data from 106 domestic CDQ boilers were statistically analyzed to identify macroscopic failure patterns. Second, a full-scale CFD model from the CDQ outlet to the boiler inlet was established to quantitatively analyze flow field distribution and erosion rates. Finally, SEM/EDS and XRD were employed to characterize the microstructure, elemental distribution, and corrosion products of the failed tube sections, thereby revealing the microscopic corrosion mechanism. Macroscopic statistics indicate a significant positive correlation between high-sulfur coke, large-scale units and a high tube burst rate. CFD simulations quantitatively reveal a "gas flow deviation" phenomenon, causing local flue gas velocities to reach 3.5 times the average and a theoretical erosion thinning exceeding 0.5 mm/a. Microscopic analysis at an approximate wall temperature of 500 ℃ shows sulfur enrichment up to 1.33%(atomic fraction) in the corrosion layer of the failed tube section, and FeS formation is detected, confirming elemental sulfur as the key chemical factor destroying the protective oxide scale. Based on these findings, a coupled failure physical model of "mechanical scale removal-chemical corrosion-product exfoliation" was constructed, indicating that the synergistic effect leads to a failure rate far exceeding the sum of individual factors. Subsequently, an integrated protection strategy was proposed, encompassing material upgrade (TP321H/TP347H), installation of anti-wear shields, flow field homogenization modification, and source control of the corrosive medium. Following the application of this strategy in a 170 t/h CDQ boiler at a coking plant in Shanxi, the first tube burst cycle was extended from an average of 11.6 months to over 36 months, avoiding direct and indirect economic losses exceeding 6.28 million yuan per incident. This study not only provides an effective solution for the failure of CDQ boilers but also offers a universal technical pathway for preventing similar coupled failures in other high-temperature dust-laden industrial installations.
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