This review focuses on the energy structure of iron and steel production and a feasible development path for carbon reduction. The process path and feasible development direction of carbon emission reduction in the iron and steel industry have been analyzed from the perspective of the carbon–electricity–hydrogen ternary relationship. Frontier technologies such as “hydrogen replacing carbon” are being developed worldwide. Combining the high efficiency of microwave electric-thermal conversion with the high efficiency and pollution-free advantages of hydrogen-reducing agents may drive future developments. In this review, a process path for “microwave + hydrogen” synergistic metallurgy is proposed. The reduction of magnetite powder by H₂ (CO) in a microwave field versus in a conventional field is compared. The driving effect of the microwave field is found to be significant, and the synergistic reduction effect of microwaves with H₂ is far greater than that of CO.

Surface quality control of hot-dip galvanized sheets is a critical research topic in the metallurgical industry. Zinc dross, the most common surface defect in the hot-dip galvanizing process, significantly affects the sheet’s service performance. In this manuscript, a novel magnetic flux leakage (MFL) detection method was proposed to detect zinc dross defects on the surface of hot-dip galvanized steel sheets. Instead of using exciting coils in traditional methods, a tiny permanent magnet with a millimeter magnitude was employed to reduce the size and weight of the equipment. Additionally, a high-precision tunnel magnetoresistance (TMR) sensor with a sensitivity of 300 mV/V/Oe was selected to achieve higher detection accuracy. The experimental setup was established, and the x-axis direction (sample movement direction) was determined as the best measurement axis by vector analysis through experiments and numerical simulation. The detection results indicate that this novel MFL detection method could detect industrial zinc dross with an equivalent size of 400 μm, with high signal repeatability and signal-to-noise ratio. In the range of 0–1200 mm/s, the detection speed has almost no effect on the measurement signal, which indicates that this novel method has higher adaptability to various conditions. The multi-path scanning method with a single probe was used to simulate the array measurement to detect a rectangular area of 30 × 60 mm. Ten zinc dross defects were detected across eight measurement paths with 4 mm intervals, and the positions of these zinc dross defects were successfully reconstructed. The research results indicate that this novel MFL detection method is simple and feasible. Furthermore, the implementation of array measurements provides valuable guidance for subsequent in-depth research and potential industrial applications in the future.

To optimize the hydrodynamic conditions of the converter vanadium extraction process, a three-dimensional multiphase flow model of the top-blowing system in a 200 t vanadium extraction converter was established based on computational fluid dynamics (CFD). Conventional 3-hole and “3+1”-hole (with a central nozzle) oxygen lance schemes were designed to investigate the effects of nozzle design Mach numbers and inter-nozzle flow distributions on jet characteristics, impact cavity morphology, and internal molten bath flow fields, aiming to select the optimal oxygen lance nozzle structure. The results indicate that for oxygen lances without a central nozzle, lowering the design Mach number mitigates shock wave energy dissipation and enlarges the gas–liquid reaction surface area; however, due to the lack of longitudinal penetrating force from a central jet, a large stagnation dead zone is prone to forming at the bottom. For oxygen lances with a central nozzle, the inter-nozzle flow distribution governs the impact cavity morphology and the evolution of the flow field. Excessive central flow causes the impact cavity to exhibit a “deep and narrow” profile and exacerbates surface kinetic energy dissipation, whereas insufficient central flow results in a “shallow and wide” cavity that makes it difficult to drive deep circulation. Based on a multi-objective evaluation, the “3+1” configuration adopting a 1:1 balanced flow ratio between the central nozzle and a single peripheral nozzle (Case 2#) effectively balances the allocation of jet momentum between radial expansion and longitudinal penetration, achieving synergistic optimization of the gas–liquid reaction interface expansion and deep-bath stirring, thus serving as the optimal scheme. The findings of this study provide an important theoretical reference for the engineering design and industrial trials of oxygen lance nozzles in large-tonnage vanadium extraction converters.

Converter steelmaking remains the dominant route for global steel production, and the double-slag process is an important refining method that merits further study. In this work, a MATLAB-based mathematical model was developed for the double-slag process under a fixed dephosphorization rate, focusing on slag control during the low-temperature dephosphorization stage (1360–1400 °C) and the subsequent decarburization stage. The model was used to guide industrial trials and analyze the effect of the deslagging ratio (Rds) on slag control and process behavior. The results show that: (1) under a given Rds, the double-slag process can theoretically approach stable slag control and slag volume with increasing decarburization slag recycling cycles; (2) at a fixed dephosphorization rate, changes in Rds affect both the total amount of slag-forming materials and their distribution between refining stages; (3) although the double-slag process reduces slag-forming material consumption compared with the single-slag process and conventional low-slag practice, it does not necessarily guarantee low-slag smelting; and (4) an optimal Rds exists under specific conditions, indicating that a higher deslagging ratio is not always beneficial and must be balanced with effective phosphorus removal. Industrial trials showed that the compliance rate of key slag parameters exceeded 60%, the dephosphorization rate during the dephosphorization stage was above 60%, and the overall dephosphorization rate exceeded 90% on average. The recycling of decarburization slag also showed complex effects on phosphorus removal in subsequent heats, indicating that its influence should be evaluated over multiple cycles rather than from isolated heats. Therefore, ideal stability predicted by the model cannot be fully achieved in industrial practice, and controlled recycling combined with timely slag renewal is required for process optimization.

Weathering steels have been widely used in transportation, energy facilities, and civil infrastructure because of their good atmospheric corrosion resistance and long service life. Their corrosion resistance is generally achieved by adding alloying elements such as Cu, P, Cr, and Ni, which promote the formation of a stable and protective rust layer. Among these elements, however, Ni and Cr are relatively expensive and their resources are limited. Therefore, reducing the use of Ni and Cr while maintaining good corrosion resistance has become an important issue in the development of weathering steels. Recent studies have demonstrated that rare-earth elements can markedly improve the corrosion resistance of steels through multiple mechanisms, including optimization of rust-layer structure, microstructural refinement, inclusion modification, and regulation of grain-boundary characteristics. Rare-earth microalloying therefore provides an effective approach to reducing the consumption of conventional alloying elements in weathering steels. This paper systematically reviews the corrosion mechanisms of weathering steels, the evolution of rust-layer structures, and the roles of alloying elements, with particular emphasis on the effects of Cu, P, Cr, and Ni on the densification and stabilization of rust layers. The microalloying effects of rare-earth elements, their inclusion-modification behavior, and their deoxidation and desulfurization mechanisms are also summarized, and their roles in reducing pitting susceptibility and promoting the formation of stable protective rust layers are clarified. In addition, the occurrence states of rare-earth elements in steel and their effects on performance stability are discussed. Key challenges encountered in the industrial application of rare-earth steels, including fluctuations in rare-earth yield and continuous-casting nozzle clogging, are also summarized. The available evidence indicates that the effective application of rare-earth elements in weathering steels remains constrained by molten-steel cleanliness, inclusion control, and the stability of continuous-casting operations. Future research should focus on technologies for the stable addition and controlled occurrence of rare-earth elements under low-oxygen and low-sulfur smelting conditions, thereby enabling the efficient utilization and stable industrial application of abundant rare-earth resources in weathering steels.

Given the increasing demand for low-phosphorus molten iron in high-value-added steel production and the rising phosphorus content in raw materials caused by the use of high-phosphorus ores in blast furnaces, the traditional converter single-slag process faces challenges such as high dephosphorization pressure, high slag consumption, and unstable endpoint control. This study systematically investigates the process principles and key influencing factors of the converter double-slag method (MURC process) as an efficient pretreatment technology for molten iron. Through thermodynamic analysis combined with industrial tests, the core process parameters affecting dephosphorization efficiency were identified, including temperature, slag basicity (R), iron oxide (T.Fe) content, and bottom-blowing stirring intensity. The results show that the optimal temperature during the dephosphorization stage is 1350–1400 °C, with slag alkalinity controlled at 1.6–2.0 and T.Fe content maintained at 19–23%. During the decarburization stage, the optimal temperature is 1620–1640 °C, and the final slag alkalinity should be increased to above 3.5. After applying the optimized “low-high-low” oxygen supply pattern and enhanced bottom-blowing stirring (0.04–0.20 Nm³/(t·min)), significant improvements were achieved in industrial practice on 180-t and 60-t converters. Lime consumption was reduced by more than 30%, the average endpoint phosphorus content decreased by approximately 0.005%, the phosphorus removal rate remained stable at above 90%, and the oxygen content in molten steel at the endpoint decreased by 50–100 ppm. This study provides a systematic theoretical basis and practical guidance for efficient and stable dephosphorization using the converter double-slag process.