Based on the essential understanding of the "three elements" （"flow", "program", and "process network"）, "three flows" （mass flow, energy flow, and information flow）, "five dimensions" （mass, energy, information, time, and space）, and "three flows and one state" （mass flow, energy flow, and information flow are in a dynamic-ordered, collaborative-continuous operating state） in the dynamic operation of manufacturing processes, it was proposed that when facing the smart issues of open, complex, and dynamic process systems, the physical essence of "three flows and one state" should be taken as the starting point, the transformation of thinking mode should be emphasized and the research on engineering methodology should be strengthened. “Smart” steel plants includes the essential “smart” of the entire manufacturing process and the extended “smart” operation and service related to supply and service systems. Its essence is to build a cyber-physical system（CPS） and achieve multi-objective “smart” of the entire process with the goal of "one flow two chains" framework. The construction of a cyber-physical system requires mutual support and integration between the cyber system side and the physical system side. The structure of physical systems should make it easy to import cyber information, and the cyber system side needs to adapt to the characteristics of the overall operation of physical system, effectively achieving the system's self-perception, self-decision-making, self-execution, and self-adaptation. Finally, concepts and ideas related to energy flow, energy flow networks, and energy center construction were proposed.

As an emerging disciplinary branch driving the green, intelligent, and brand-oriented development of the steel industry, metallurgical process engineering aims to achieve efficient product manufacturing, energy cascade utilization, and resource recycling through the systematic integration and optimization of metallurgical manufacturing processes.The theoretical innovations of this system are systematically elaborated, including the monograph Metallurgical Process Engineering, the theory of cyber-physical systems （CPS）, and the dynamic precision design method. The physical essence of the intelligent transformation in process industries is revealed, along with the evolutionary path of the "material flow-energy flow-information flow" trinity coupling mechanism. Building on these theoretical breakthroughs, key technologies such as "interface" technology, dynamic simulation, and dynamic Gantt charts have been successfully developed and applied at scale in landmark projects like Shougang Jingtang and HBIS Tangsteel's New Area. These applications have delivered significant improvements in production efficiency, energy consumption, and product quality. The current challenges are further analyzed, including insufficient analytical tools, limitations in the research system, and restricted cross-industry applications. Future directions are proposed, such as strengthening undergraduate education, promoting dynamic precision design theory and methods, establishing plant-wide intelligent systems, and fostering synergistic industrial ecosystems integrating metallurgy, chemical engineering, and cement production. Practice has demonstrated that metallurgical process engineering not only advances the expansion and refinement of metallurgical engineering as a discipline but also provides theoretical guidance and technical support for the low-carbon and high-quality development of the steel industry. It holds substantial academic value and practical significance for engineering applications.

As a key basic material for economic and social development, steel materials have always been important basic materials for economic and social development in the past, present and future. Steel metallurgical engineering is an important industrial foundation supporting the development of modern industrial society. After more than one hundred years of development, steel metallurgical engineering design, along with the interactive promotion and iterative improvement of science, technology and engineering, has evolved and integrated from the knowledge, experience and inspiration of individual design engineers into an engineering activity that integrates multiple disciplines, specialties and fields, as well as an engineering innovation that is organized, collaborative and integrated. Modern steel metallurgical engineering design encompasses numerous aspects such as process design, technological design, equipment design, energy design, and auxiliary system design for steel manufacturing. It is an integrated engineering design centered on the entire steel plant. Modern steel metallurgical engineering design includes various designing aspects, such as process, technology, equipment, energy and auxiliary system. The design centers on the entire steel plant, achieving integration and consolidation. The modernization of steel metallurgical engineering design integrates advanced theories, methods, and research achievements from fundamental science, technical science, and engineering science. Through the reasonable selection and effective integration of steel and metallurgy engineering elements, on the basis of basic elements, principles, process technologies, equipment, devices, procedures, management and evaluation, it benefits to build a competitive engineering entity, the integration and construction process must incorporate advanced processes, reasonable structure, optimized functions and excellent efficiency. Engineering design is the core link and important process of transforming innovative thinking and engineering concepts into actual productive forces. The design of steel metallurgical engineering adopts the systems engineering approach, focusing on aspects such as the structuring, fictionalization, efficiency of the steel plant, and the overall environmental adaptability of the project. The multi-objective optimization problem of the whole process of steel metallurgy involves the comprehensive consideration of structure, function and dynamic operation,which is the most important proposition in the engineering design of steel metallurgy. The connotation and methods of the engineering design innovation and operation practice effect of Shougang Jingtang steel plant were studied and discussed, and the main connotations and thoughts of conceptual design, top-level design and dynamic precise design of the new generation of steel plant engineering were expounded.

Against the backdrop of overall layout adjustment and high-quality development in China's steel industry, there is an urgent need for the overall design of green, intelligent, and efficient for the relocation and new construction projects of steel enterprises. The core connotation, development stages, and engineering applications of the overall design for a steel plant were systematically elaborated, and the goals of compact manufacturing process structure, efficient operation, and intelligence were achieved through the integration of multidisciplinary technologies. The overall design had gone through four stages, precise design, energy flow network optimization, greening, intelligence and branding, and efficient and compactness. The single process optimization was gradually shifting towards multi-objective ecological design, and the key technological system covering process simulation, energy cascade utilization, intelligent manufacturing, compact layout was formed. Taking the Tang-Steel New Area and Shi-Steel Relocation Project of HBIS Group Co.,Ltd. as examples, the successful application of the overall design in long/short process steel plants had been verified. Looking ahead to the future, in the face of the "dual carbon" goal, a low-carbon process route of hydrogen metallurgy+electric furnace/melting furnace was proposed, clarifying low-cost hydrogen sources, direct reduction iron processes, interface technology, and energy flow network construction as future research priorities, providing technical path references for the green and low-carbon transformation of steel industry.

Under the backdrop of global manufacturing upgrading and high-quality development in the steel industry, the sector urgently needs to break through the limitations of single-process automation and explore intelligent transformation paths for the entire steel manufacturing process. To achieve dynamic order and collaborative continuous operation in steel manufacturing processes, Tangsteel New Area leveraged its geographical relocation opportunity and implemented intelligent manufacturing construction and innovative practices based on the integration of three-flow（mass flow, energy flow and information flow） synergy and the three-network（the network of three-flow） integration, guided by metallurgical process engineering theory. The core of intelligent steel manufacturing lies in constructing a cyber-physical system that deeply integrates physical systems with cyber systems, while optimizing the open dissipative structure of steel manufacturing processes. In physical systems, process self-organization has been enhanced to achieve Laminar-flow material movement that eliminates cross-process interference, and dry network energy flow that reduces pipeline complexity and gas losses, thereby decreasing the entropy generation rate of dissipative structures. The cyber system relies on industrial internet platform based on cloud edge architecture and functional architecture of integrated intelligent manufacturing system to provide regulatory instructions, generate corresponding organizational forces to help, support and regulate the physical system, and realize the input of negative entropy flow from the cyber system to the physical system. while connecting cyber system and physical system through sensors and actuators, establishing a closed-loop interaction mechanism featuring state perception, real-time analysis, scientific decision-making, and precise execution. Tangsteel's intelligent of steel manufacturing process practice is not only theoretically innovative theory of metallurgical manufacturing process, but also delivers significant economic and social benefits in production efficiency, resource allocation, cost reduction, quality improvement, which makes Tangsteel New Area become intelligent model of a new generation metallurgical manufacturing process steel mill.

The typical iron and steel production routes are primarily categorized into three types. There are the blast furnace-basic oxygen furnace （BF-BOF） route utilizing natural resources, the electric arc furnace （EAF） route based on scrap steel, and the hydrogen-based direct reduced iron-electric arc furnace （H₂-DRI-EAF） route. Quantifying the energy consumption, energy efficiency, and CO₂ emission metrics of these three routes can reveal differences in energy intensity, potential for efficiency enhancement, and opportunities for CO₂ emission reduction, thereby providing basic concepts, analytical methodologies and foundational data to support process optimization, innovation, and synergistic complementarity among different routes. Based on metallurgical process engineering and thermodynamic principles, critical concepts and computational formulas for product-level versus process-level energy consumption, energy efficiency, and CO₂ emissions were proposed, with an in-depth analysis of their distinctions and interrelationships. By integrating material-energy flow analysis and operational data from steel sites, the product energy consumption, system energy efficiency, and product CO₂ emissions of the three routes were calculated and comparatively analyzed. The results indicate that the BF-BOF route exhibits product energy consumption of 462.7 kg/t, system energy efficiency of 62.2%, and CO₂ emission intensity of 1 038.5 kg/t. The EAF route demonstrates product energy consumption of 164.1 kg/t, system energy efficiency of 25.3%, and CO₂ emission intensity of 633.9 kg/t. The H₂-DRI-EAF route shows product energy consumption of 409.3 kg/t, system energy efficiency of 34.3%, and CO₂ emission intensity of 639.9 kg/t. Each route presents distinct advantages and limitations. The BF-BOF route excels in energy efficiency but suffers from high energy consumption, the EAF route offers energy-saving benefits but exhibits the lowest energy efficiency, and the H₂-DRI-EAF route demonstrates CO₂ emission reduction advantages but lags in energy consumption and efficiency performance.

There are many uncertain problems in the operation of iron and steel manufacturing process. Many of these uncertain problems still rely on human experience regulation, which is not conducive to automatic or intelligent regulation. Uncertainty problems can be divided into two categories, accidental uncertainty and cognitive uncertainty. Accidental uncertainty is due to the internal factors of the process system, and the number is difficult to reduce. However, by optimizing its operating structure, the range of such uncertainty problems can be narrowed. Cognitive uncertainty is due to people's insufficient cognition of the reality of process operation behavior. With the in-depth understanding of process operation behavior, the enrichment of relevant cognitive information and the improvement of tool functions, the number of cognitive uncertainty problems can be reduced. For the intelligent upgrading of iron and steel manufacturing process, it should be based on the principle of building cyber-physical integration system, and carry out collaborative research from the process side and the information side. Through the process side research and with the help of relevant rules, a process base with relatively transparent and predictable path optimization and output parameters can be formed to reduce the uncertainty of operation behavior and improve the cognitive ability of process operation behavior. The information side research is to use intelligent means to empower the steel manufacturing process and improve its operation efficiency and quality. The numerical simulation of multi-process collaborative operation of the whole process is one of the important contents of information side research.

As a typical process manufacturing industry, steel industry has the characteristics of diversity, complexity and variability, and faces the constraints and pressures of multi-objective collaborative optimization such as cost, quality and environment. Under the guidance of metallurgical process engineering theory, WISDRI has carried out research and practice on process optimization and intelligent operation of steel project construction, steel production and operation. Combined with the characteristics of the steel process and its rich experience in EPC project management, it has developed a digital intelligent construction management system for metallurgical engineering, driven by data as the core, to open up the upstream and downstream process chain of EPC projects, and effectively improve the quality and efficiency of technical services through the intelligent and digital construction processes such as design, procurement, construction, operation and maintenance. In the Yukun project, the effect of reducing quality change by 80% and improving overall efficiency by 35% was achieved. Based on the self-developed industrial internet platform WISDRI DiPlant, through the integrated optimization of material flow, energy flow and information flow, as well as the corresponding collaborative optimization of process networks and operating procedures, it has created an overall solution for cross-process and systematic intelligent manufacturing covering the entire process of the steel industry. The intelligent application of intelligent blast furnace, iron and steel interface optimization, intelligent control system of cold rolling products and so on are introduced. The results show that the comprehensive coke ratio of blast furnace is reduced by 13 kg/t, the iron temperature is reduced by 30-50 ℃, and the loss of high grade non-oriented silicon steel is reduced by 17.6%. With the gradual deepening of the understanding of metallurgical process engineering and the continuous development and improvement of intelligent and digital technology, the guiding role of metallurgical process engineering theory will be further revealed.

The metallurgical industry in the 21^st century is facing the dual challenges of greenization and intelligence, and its core breakthrough lies in systematic theoretical innovation and engineering practice. Metallurgical Process Engineering（MPE）, as an emerging branch of metallurgy, is based on the theory of dissipative structures and focuses on the global optimization of the structure-function-efficiency of metallurgical manufacturing processes, providing a scientific framework for solving low-carbon issues in the steel industry. Firstly, the self-organizing characteristics of metallurgical manufacturing processes as dynamic open systems based on dissipative structure theory was explored, and it was pointed out that the "six theories" proposed by MPE, i.e. dynamism, structurity, continuity, embedding, synergetics, and functionalism, were key theoretical tools for constructing dissipative structures and optimizing dissipative processes in metallurgical manufacturing processes. Secondly, the path of low-carbon development in the steel industry from a physical essence perspective was analyzed, it was pointed out that reconstructing the dissipation path of "mass flow-energy flow-information flow" in the "one process two chains", i.e. manufacturing process, supply chain and service chain, was the core of low-carbon transformation in the steel industry. Then a dynamic circular network across industrial chains would be formed and the minimization of system dissipation would be promoted. And the main measures for constructing dissipative structures and optimizing dissipation processes at different scales for the in the "one process two chains" were analyzed. Finally, regarding the carbon footprint control of the entire steel industry chain, it was proposed that the essence of researching the carbon footprint of the entire steel industry chain was to minimize carbon emission dissipation, optimize multi-scale dissipation phenomena, dissipation structures, and dissipation processes throughout the entire industry chain. And it was pointed out that the quantitative evaluation of the carbon footprint of the entire steel industry chain was an important foundation for its control. In the future, research needs to be conducted on the construction of a carbon footprint evaluation model system for the entire steel industry chain products, the development and application of high-quality localized databases and digital tools.

The integrated technology of continuous casting and rolling is the third generation technology of the evolution for thin slab continuous casting and rolling, commonly known as thin slab endless rolling. It integrates traditional discrete processes such as continuous casting, heating, and rolling through a system to achieve fully continuous production from molten steel to steel coils, eliminating the main interface of the traditional between continuous casting and hot rolling process and reflecting the development trend of metallurgical processes evolving from intermittent to continuous. It introduced the key technologies for achieving integrated technology of continuous casting and rolling. The technical characteristics of integrated technology continuous casting and rolling were analyzed from the perspective of metallurgical process, and it was proposed that the process involved many physical and chemical processes such as steel cleaning, solidification, and pressure processing, which required extremely high requirements for dynamic and precise coordinated control of material flow. The steel throughput index was defined as an indicator to characterize the material flow coordination status and process technology level of the integrated technology continuous casting and rolling, and to clarify coordination relationship of material flow between continuous casting and hot rolling processes on different types of production lines. The energy flow transfer at the interface between continuous casting and hot rolling on different types of continuous casting and rolling and under different process states was studied. It is pointed out that the comprehensive and smooth flow of information is the key to the integrated technology of continuous casting and rolling, and is the basic condition for precise coordinated control of material flow and efficient transmission of energy flow. The development direction of integrated technology of continuous casting and rolling was analyzed, and the development trend of production process of hot-rolled strip steel was pointed out.

The steelmaking production scheduling plan is of great significance for the collaboration, continuity, and efficiency of the steel manufacturing process. At present, the production scheduling model mainly takes minimizing completion time, equipment idle time and other time related indicators as the objective function, and lacks consideration for the control of steel temperature parameters, which is not suitable for the transformation and upgrading of the steel industry and the increasingly stringent quality requirements. Therefore, the objective function of molten steel temperature was introduced as an indicator to measure energy consumption and product quality, and an optimization model for steelmaking production scheduling based on the synergy of time and temperature was constructed. The model is solved using an improved genetic algorithm, which maximizes the carrying capacity of the refining process by setting variable processing times, and provides balanced choices among multiple scheduling schemes. At the same time, in order to address the difficulty of solving multi-objective optimization problems, the Epsilon constraint method was adopted to transform the objective function and adjust the feasible region of the main objective function solution, improving the efficiency of the model solution and ensuring its timeliness. Compared with traditional weighting methods, it reduces redundant calculations. A simulation experiment was conducted using the main production mode of a certain steel plant, and the results showed that the scheduling plan developed through optimizing the model can achieve an orderly and conflict free production process as well as continuous casting of the casting machine. Moreover, the scheduling plan that fully considers the temperature drop of steel, compared to the scheduling plan that only ensures compliance with temperature regulations, reduces the average total temperature drop from 113.3 ℃ to 104.4 ℃ during the steelmaking to continuous casting process, and from 26.8 ℃ to 21.7 ℃ during the RH refining process. This optimization model facilitates scheduling personnel to develop scheduling plans with relatively balanced time and temperature targets during the production process, which is beneficial for reducing heat loss and improving energy efficiency in the steelmaking process, reducing fluctuations in steel temperature, and further ensuring stable product quality.

Time has a decisive influence on the coordinated operation among each processes in the manufacturing process. To achieve the dynamic and orderly operation of the manufacturing process, the coordination of each process in terms of time factors is very importance. The theoretical basis and methods of process optimization were introduced. Focusing on the thin plate steel-making system of Masteel, through events and time analysis, the key factors affecting time were proposed, such as casting speed and empty ladle operation time. Based on this, the primary measures to improve the operational efficiency of the steelmaking system were proposed, such as shortening the oxygen supply time and tapping time of the converter, reducing the use frequency of the LF（label furnace）, increasing the casting speed and continuous casting times of CC（continuous casting）, and reducing the running time of empty ladles and the transportation time of heavy ladles. Through the process path, process technology and interface technology research, the processing time and waiting time of each process had been shortened, and the operation of the process had been optimized. The dynamic-orderly, collaborative-continuous operation of the process has been basically achieved, significantly improving the production efficiency of the process. The converter operation cycle, CC pouring cycle, and empty ladle operation time are reduced by 6 min, 3.3-9.6 min, and 23-40 min, respectively. The number of online ladles decrease from 17 to 14. The crude steel output has increased from 7.44 Mt/a to 9.73 Mt/a, approximately 30% has been increased.

The steelmaking-continuous casting （SCC） process is a critical segment in the steel manufacturing workflow, where the continuity and stability of operations play a vital role in ensuring overall production efficiency and product quality. However, in real-world industrial environments, the presence of complex and multiple uncertainty events severely constrains the continuity and stability of production, posing significant challenges to improving metallurgical efficiency and ensuring consistent product quality. Effectively identifying the root causes of these uncertainties and enabling rapid and efficient responses upon their occurrence have become key issues that modern steel enterprises must urgently address. Production disturbances in the SCC process can be broadly categorized into process-related, material-related, equipment-related, and personnel-related types. Among these, process disturbances occur most frequently and have a significant impact on the smooth operation of SCC production. Based on actual production conditions in steel plants, the sources and categories of disturbances are systematically reviewed and classified in the SCC process, with an in-depth focus on process-related disturbances. Subsequently, relevant research is summarized and analyzed concerning the characterization for the impact of process disturbances on production, dynamic scheduling strategies in response to such disturbances, and evaluation methods for their applicability. Finally, grounded in practical production scenarios, the effects of process disturbances in the SCC segment are classified into time-related and order-related disturbance. It then proposes targeted response strategies and a supporting technical framework aimed at enabling rapid responses and accurate characterization of process disturbances, thereby facilitating precise matching of appropriate countermeasures. This approach is intended to ensure high-efficiency and high-quality production in the SCC process, and to provide robust support for achieving dynamic-orderly, and synergetic-collaborative continuous operations throughout the steel manufacturing process.

Accurately obtaining the temperature information of hot metal in advance is of great significance for optimizing the production organization and adjusting the operating parameters of subsequent hot metal scheduling, pretreatment, and smelting at the ironmaking-steelmaking interface. Regarding the prediction of hot metal temperature in the muti-functional ladle mode of the ironmaking-steelmaking interface, the influencing factors of hot metal temperature at the ironmaking-steelmaking interface were first sorted out based on the characteristics of the muti-functional ladle mode process flow. Secondly, a multi process operation dataset of the ironmaking-steelmaking interface was obtained. Based on missing value processing, outlier processing, and data normalization, correlation analysis, recursive feature elimination, and metallurgical process analysis were used for feature selection. 8 and 11 input feature variables were determined for the iron temperature prediction models of non-ending ladles and ending ladles respectively. A desulfurizing station inlet temperature prediction model based on GBDT, XGBoost, and TPE-XGBoost was constructed. Finally, the predictive performance was validated using historical production data. The results showed that among the three prediction models, the model based on TPE-XGBoost had the best prediction performance, with a hit rate of 85.52% within the range of -15-15 ℃ for prediction error, a root mean square error of 10.8 ℃, and an average absolute percentage error of 0.549%. Compared with models for non-ending ladles, the overall prediction accuracy of models for ending ladles is lower, which is related to the higher complexity of ending ladle operation and the presence of more noise data. Steel enterprises should attach importance to and strengthen data quality management to further improve the applicability of models.

Against the backdrop of achieving "carbon peak" and "carbon neutrality" targets, the low-carbon transformation of China's iron and steel industry represents a critical imperative. Direct rolling of long profiles, which eliminates the reheating furnace, offers significant potential for energy savings and emission reducing, making it becoming a key low-carbon process integration technology. Temperature uniformity, head-to-tail temperature difference, material flow interface coordination and quality stability control in the casting-rolling interfaces of both single and multi strand coupled direct rolling production lines for long profiles were investigated. It reveals that in single-strand direct rolling lines, the minimum required billet temperature is 950 ℃, with a head-to-tail temperature difference not exceeding 50 ℃. The straight rolling rate achievable with laminar cooling operations in such lines can reach 98%. Steady-state operation at the casting-rolling interface requires synchronized mass flow rates between continuous casting and rolling. Utilizing prediction models for billet temperature and maximum waiting time enables coordinated billet allocation from multiple lines, reducing thermal losses and improving interfacial logistics efficiency. Additionally, optimized laminar operation modes is proposed for material and energy flow integration in two typical production capacities （1 Mt/a and 3 Mt/a） in long product electric arc furnace （EAF）-direct rolling lines, thereby enabling efficient casting-rolling interface connection in the direct rolling process.

The synergy between material flow and energy flow serves as one of the pivotal entry points for optimizing energy systems and achieving energy conservation in iron and steel enterprises. The dynamic regulation of energy systems in steel enterprises was investigated based on material-energy flow synergy. Through macroscopic operational dynamics analysis of energy carriers such as gas, steam, and electricity within the energy flow and energy flow network, a dynamic regulation mechanism was proposed for energy flow and energy flow networks in steel manufacturing processes from two perspectives. First, under specific external environments and internal conditions, it coordinated operational parameters across processes/equipment to identify and rapidly achieve a reasonable steady-state "attractor" with minimal dissipation. Second, it perceived intrinsic uncertainties and external "stimuli" in the steel manufacturing process, enabling timely or predictive dynamic "responses" to either adaptively maintain the steady-state attractor with minimal dissipation or autonomously initiate transitions toward new steady states.The energy flow dynamic regulation process centered around a five-dimensional dynamic Gantt chart was analyzed, which predicted the production, consumption, and buffering states and trends of major energy carriers while providing anticipated regulatory action commands. Through this five-dimensional dynamic Gantt chart, the objectives of anticipating changes, timely adjustments, and optimized operations could be achieved. A hierarchical functional structure and supporting platform for multi-energy-carrier dynamic regulation were designed, comprising two levels, multi-carrier dynamic optimization and single-carrier dynamic regulation. The multi-carrier level focused on centralized collaborative optimization, while the single-carrier level operated as a distributed control system. The digital platform featured operational states including real-time operation, historical state backtracking, and future-state simulation, supporting continuous functional improvement. Finally, the hierarchical roles of material-energy flow synergy in energy system dynamic regulation was summarized, emphasizing the need to advance from information exchange and decision support levels to the level of collaborative optimization.

Optimization of the ferruginous mass flow operation within the steel manufacturing process is a critical approach to achieving energy conservation, cost reduction, and efficiency enhancement. Addressing the prevailing confusion in the steel industry between the concepts of "energy consumption" and "energy efficiency",where evaluation metrics based on energy consumption per ton of steel or per procedure fail to account for differences across products and process paths, an evaluation method for energy efficiency in the steel product manufacturing process and its workflows were proposed. This method used intermediate products as a benchmark to quantify the dynamic coupling relationship between the ferruginous mass flow and energy flow. The concept of "process effective energy" was introduced, defined as the sum of the energy acquired to produce a unit of product meeting metallurgical targets and the reusable energy recovered from the process, within the metallurgical operations of each procedure through which the energy flow carried by the ferruginous mass flow passes. Process energy efficiency was calculated as the ratio of effective energy to the total energy input and supplied to the process, thereby characterizing the energy conversion and utilization effectiveness of the ferruginous mass flow across the metallurgical processes of each procedure. By analyzing the input-output relationships of mass flow and energy flow in multi-procedure operations, combined with the characteristics of metallurgical processes, computational models were developed for the energy efficiency of chemical metallurgical processes （converter and refining） and physical metallurgical processes （continuous casting solidification）, alongside methods for calculating interface energy efficiency between procedures and overall process energy efficiency. Through the input-output analysis of mass flow and energy flow across multiple procedures, combined with thermodynamic equilibrium relationships, dynamic tracking of energy efficiency from individual procedures to the entire process was achieved. Using production data from a specific converter steel plant in China as a case study, the energy efficiency variations across different process paths, metallurgical equipment, and products were quantitatively analyzed. The results demonstrate that the energy efficiency evaluation method based on the operational characteristics of the ferruginous mass flow provides a decision-making foundation for steel enterprises to optimize process control and path selection, implement dynamic operation optimization in production, and achieve energy saving and carbon reduction.

Based on the process characteristics of China's steel industry and the progress of hydrogen metallurgy technology, hydrogen-rich ironmaking in blast furnace is an important path for reducing carbon emissions in the current scale of China's steel industry. The basic principles of reducing carbon emissions, lowering energy consumption per ton of iron, and improving production efficiency by enriching hydrogen in blast furnaces was explained. It analyzed the characteristics and problems of different smelting process modes based on hydrogen rich coupling furnace top gas circulation, high oxygen enrichment, and preheating. The carbon reduction under modes such as hydrogen rich coupling with top gas circulation and electric heating in blast furnaces can reach over 50%, and the development trend of high-efficiency, low-carbon, and green blast furnace ironmaking technology is high efficiency. The experiment and industrial demonstration of pure hydrogen injection into blast furnaces, as well as the freezing dissection study of hydrogen rich blast furnaces, provide foundation for the construction of prototype of low-carbon smelting process for hydrogen rich blast furnaces. The lack of hydrogen sources in large-scale economies, the failure to connect downstream low-carbon product consumption market chains, and the failure to implement carbon taxes have resulted in a lack of economic viability for hydrogen metallurgy technology, which is bottleneck hindering its development. Building a globally recognized high-quality standard system and low-carbon industry ecosystem based on top-level design, accelerating core technology research and breaking through scale bottlenecks, the development of hydrogen metallurgy technology is promoted by incorporating monitoring and trading systems, and utilizing carbon trading mechanisms to encourage steel enterprises to accelerate the adoption of low-carbon technologies. With the transition from traditional carbon metallurgy to hydrogen metallurgy, hydrogen flow as a reducing agent and fuel has become a new variable that needs to be considered in the upgrading and transformation of traditional metallurgical processes. It poses new challenges for the overall process optimization and functional optimization of metallurgical processes, and has become an important research topic in metallurgical process engineering.

As a pillar of the national economy, the steel industry urgently needs to reduce energy consumption and carbon emissions in the context of carbon neutrality. Steel scrap, a low-carbon emissions ferrous resource, has seen increasing production. Using scrap steel is an effective mean of rapid carbon emissions reduction. However, residual elements in steel scrap significantly hinder its high-quality utilization. The residual elements in steels and their effects on microstructure and properties were systematically analyzed. Based on their chemical and metallurgical characteristics, key residual elements were selected and categorized into three groups, namely Cu, Cr, Ni, and Mo with relatively high contents, As, Sn, Sb, Bi with easy segregation and polymerization, and impurity elements N and S. On this basis, the content characteristics of residual elements in scrap steel from different countries, enterprises and types were analyzed. The maximum content of residual elements in scrap steel at home and abroad from 2000 to 2024 was investigated. Combined with the measured data of domestic electric furnace process steel enterprises, the maximum content range of the main residual elements in scrap steel was clarified, and the action mechanism of the main residual elements was introduced, providing a basis for the high-quality utilization of scrap steel.

Industrial trials were conducted on a wear-resistant steel to determine the effect of lanthanum on inclusions modification in the steel. The FactSage8.2 software was further used to comprehensively analyze the thermodynamics of inclusion formation in wear-resistant steel, clarify the stable phase diagram of inclusions in lanthanum-bearing wear-resistant steel. Effects of the total oxygen, total lanthanum, total calcium content and temperature on the evolution of inclusions in steel were analyzed. Without the addition of lanthanum-iron alloy, inclusions in the molten steel after VD vacuum broken were mainly Al₂O₃ inclusions and a small amount of CaO+CaS inclusions, and the Al₂O₃ content reached over 95%. After the calcium treatment, the content of CaS and CaO in inclusions increased significantly, and the inclusions in the continuous casting billet were mainly Al₂O₃-CaS-CaO. Under the condition of adding LaFe alloy, inclusions in the steel changed from Al₂O₃ to La₂O₂S, and the mass fraction of La₂O₂S reached 94%. After the calcium treatment, inclusions were modified to La₂O₂S-CaS-CaO composite inclusions. The mass fraction of La₂O₂S in inclusions in the molten steel of tundish decreased to 10%, the mass fraction of CaS decreased to 43%, while the content of Al₂O₃ and La₂O₃ had an apparent increase. Thermodynamic calculations show that with the increase of lanthanum content in steel, inclusions in the steel gradually changed from liquid calcium aluminate to LaAlO₃, and further to La₂O₂S. The possible inclusions in lanthanum-bearing wear-resistant steel were Al₂O₃, LaAl₁₁O₁₈, LaAlO₃, La₂O₂S and La₂S₃. When the T[La] mass fraction in the steel was greater than 0.004%, even if the calcium treatment made the T[Ca] mass fraction in the steel liquid 0.003%, no liquid inclusions would be generated in the steel. Inclusions were mainly LaAlO₃ and La₂O₂S. The lanthanum addition process needed to take measures to prevent nozzle clogging. The overall transformation trend of non-MnS inclusions in lanthanum-bearing wear-resistant steel during the cooling process was La₂O₂S+CaS+2CaO·SiO₂→LaAlO₃+calcium aluminate→Al₂O₃-CaS-La₂S₃. When the temperature dropped to 1 210 ℃, inclusions eventually transformed into composite inclusions of La₂S₃, CaS, Al₂O₃ and MnS. The T[O] content had little effect on MnS inclusions in the steel. The higher the T[O] content, the more Al₂O₃ accounted for in inclusions and the less CaS accounted for.

The mixing efficiency of molten pool and the dynamic characteristics of flow field for novel "ring seam-hole" oxygen lance in top-bottom combined blowing converter were systematically investigated using numerical simulation. The interaction mechanism between the bottom-blown bubble plume and the top-blown jet was investigated, with particular emphasis being placed on their combined effects on the molten pool flow and mixing behavior. It has been demonstrated that the new oxygen lance design effectively eliminates the low-speed dead zone issue in the central region of the molten pool, compared to the traditional oxygen lance. With the synergistic effect of top-bottom combined blowing, the flow rate of molten pool is significantly enhanced, and the material transfer efficiency is notably improved. The results indicate that the process parameters of bottom blowing play a crucial role in regulating the flow field of the molten pool. As the bottom blowing speed increases from 8 m/s to 20 m/s, the turbulence intensity of the molten pool increases, and the vortex center gradually shifts outward. Furthermore, the interaction between the bottom-blown bubble plume and the top-blown jet alters the impact area and penetration depth of the jet, thereby optimizing the flow field distribution within the molten pool and enhancing the mixing efficiency. When the flow ratios are full-nozzle top blowing, 1∶24, and 1∶17, the mixing time is observed to decrease gradually with the increase of bottom blowing speed. However, when the top blowing flow ratio is 1∶12, the interference between the bottom-blown bubble plume and the converging jet leads to kinetic energy dissipation, which weakens the enhancement effect of stirring efficiency. It is concluded that the optimization of oxygen lance structure and top-bottom combined blowing process parameters can effectively improve the mixing efficiency of molten pool, reduce energy consumption and carbon emissions, and achieve cost reduction and efficiency improvement in the metallurgical process. A basis is provided for promoting technological innovation, enhancing production efficiency and product quality, and strongly supporting the sustainable development of the steel industry. Moreover, it offers important theoretical support and technical guidance for the implementation of an ultimate energy efficiency project and the exploration of a green and low-carbon transformation path in the steel industry.

Non-quenched and tempered free-cutting steels are widely used in the automotive and transportation industries. As the most representative steel for engine fracture-split connecting rods, C70S6 requires the development and optimization of refining slag-making processes to ensure stable control of its composition and microstructure, which holds significant industrial and academic value. Ladle refining slag systems play a critical role in secondary metallurgy, performing key functions such as deoxidation, desulfurization, inclusion absorption, and stabilization of nitrogen and sulfur content in molten steel. To address the unique compositional requirements of C70S6 steel,characterized by "three highs" （high C, high S, high N） and "two lows" （low Al, low Si）, it systematically investigated the characteristics of various refining slag compositions using FactSage thermodynamic software and the KTH（Kth-order） sulfur capacity model. A novel "dynamic slag adjustment" process was proposed to achieve precise sulfur control. At early LF refining stage, high-basicity slag was employed to enhance diffusion deoxidation, compensating for the insufficient precipitation deoxidation capability caused by low Al and Si levels, while creating favorable conditions for subsequent nitrogen pickup. At late VD stage, low-basicity slag was used to retain sulfur, meeting machinability requirements. Key findings indicate that the calcium-to-alumina ratio （C/A） and basicity （w（CaO）/w（SiO₂）） are the primary factors governing slag melting behavior. For optimal performance, at deoxidation/desulfurization stage, the slag system should maintain a basicity of 3-6, MgO mass fraction of 4%-6%, and C/A ratio of 1.5-2.2. This configuration ensures low melting point, good fluidity, and effective absorption/modification of Al₂O₃ inclusions generated during Al deoxidation. At sulfur retention stage, slag system should be adjusted to a basicity of 2.0-3.5, MgO mass fraction of 4%-6%, and C/A ratio of 2.3-3.3 to enhance sulfur preservation in the molten steel. This research provides practical guidance for refining high-carbon sulfur-bearing non-quenched steels, enabling precise control of chemical composition and cleanliness through stage-specific slag system adjustments.

Under the background of "carbon peak and carbon neutrality", carbon footprint is the most concerned indicator in the Life Cycle Assessment （LCA） system. LCA background database are necessary conditions for carbon footprint calculations. The absence of data from China has a huge impact on global carbon footprint calculations. Based on this, the method of building a localized LCA background database for China's steel industry was proposed for the first time. The LCA methodological system adopted by the background database was the core of the database development. By analyzing the differences in the calculation results of carbon footprint for steel products by different methods, it was proposed to build the background database of China's steel industry by the Attributional method, the Consequential method, and the EN15804 standard respectively, in order to be applicable to different application scenarios. The ILCD database format proposed by the European Union was adopted to record and review the entire process of data processing, ensuring data quality and guaranteeing the transparency, traceability and international interactivity of the background database. Based on the methods proposed, the life cycle background database HiQLCD of the steel industry was developed in practice. Three methods were adopted to generate a set of data each, and each set of data contained 5 815 data sets, totaling 17 445 data sets. The results of calculating the carbon footprint of pig iron using HiQLCD and a certain foreign database were compared. It shows that the localized HiQLCD database is more in line with the characteristics of the production process of Chinese products. There are significant improvements in indicators reflecting the quality of background data such as technical representativeness, geographical representativeness, temporal representativeness, and accuracy. The calculation results are more accurate and can better reflect the actual situation. This will scientifically support enterprises in calculating and reducing carbon emissions with more authentic data. Meanwhile, the transparency of the rules lays the foundation for achieving international mutual recognition of carbon footprint calculation results. The next step will be to continuously expand the coverage of the steel product database, conduct frequent iterations, gradually increase the proportion of high-quality domestic data as background data, and at the same time carry out research on the development of more complex supply chain databases.

Iron ore sintering is the most polluting production unit in the BF-BOF steel manufacturing process. The CO emissions form sintering flue gas have far exceeded those of SO₂ and NO_x. As a third-generation pollutant, CO has been identified as the focus of sintering flue gas treatment. Technical approaches such as biomass fuel substitution, thick-layer sintering, water vapor injection into the sintering bed surface, and sintering flue gas circulation can effectively reduce CO and NO_x emissions. However, challenges are posedby the large volume of sintering flue gas, diverse gas components, and significant variability in gas characteristics, resulting in high costs and low efficiency for end-of-pipe treatment technologies, particularly in coordinated CO and NO control. Based on these challenges, the generation and emission of CO and fuel-NO during the sintering process were analyzed. Both CO and fuel-NO in sintering flue gas these challenges from solid fuel combustion, where the combustion conditions of solid fuels directly determine their emissions. The thermodynamics and kinetics of CO oxidation and NO reduction within the sintering system, the influences of solid fuel occurrence states on the generation and emission CO and NO, and the catalytic mechanisms of different sintering raw materials for the reduction of NO by CO were deeply analyzed. Future research should bedirected toward investigating the coupling mechanisms of heat transfer, mass transfer, and physical fields during the combustion of quasi-particles with varying structures in the sintering bed. The establishment of a coordinated CO and NO reduction technology system suitable for the sintering process will provides a theoretical basis for promoting the comprehensive and coordinated control technology of sintering flue gas.

With the advancement of urbanization in China, the amount of urban solid waste continues to increase. There is a long way to achieve the goal of reducing urban solid waste generation. It will remain a key focus on managing the solid waste through “reduction, utilization and harmlessness” in the future. According to the concept of circular economy, the technologies for the co-processing of solid waste in industrial furnaces and kilns have progressed rapidly. The iron and steel making furnaces and kilns have obvious advantages in co-processing solid waste, such as various types of furnaces, high operating temperatures and the presence of reducing/oxidizing atmospheres. The characteristics of urban solid waste, the advantages of iron and steel making furnaces and kilns, and the current status of research and application of urban solid waste were analyzed. The difficulties of solid waste treatment and suggestions for the disposal were put forward. At present, there were many basic studies on the disposal of urban solid waste by iron and steel furnaces and kilns, but few had been verified by industrial tests. Only the disposal of scrap packaging materials had been realized in industrial application. In the future, it is necessary to promote the technologies of urban solid waste disposal by iron and steel making furnaces and kilns by building an intelligent management platform for urban solid waste, formulating relevant policies and regulations, issuing standards and specifications, and building an industry-academia-research-application collaborative pathway.