1. Introduction and Scope

2. Overview of the Published Articles

Song et al. [Contribution 1] provided an article entitled ‘Study on the Activity Model of PbO-ZnO-FeO-Fe₂O₃-SiO₂-CaO Six-Component High-Lead Slag System’. In this study, combined with the high-temperature phase diagram of the binary slag system and the ternary slag system in the PbO-ZnO-FeO-Fe₂O₃-SiO₂-CaO six-component slag system, the structural units existing in the slag were determined, and the sum of the action concentrations of all components was stipulated to be equal to 1. Based on the principle of mass conservation of each component of the slag, a component action concentration (activity) model was established to analyze the influence of slag composition changes on the activity of each structural unit. The results show that the calculated value of the activity model is in good agreement with the measured value of the experiment, and the activity of each structural unit is greatly affected by the composition of the slag, but less affected by the temperature. High temperatures are conducive to the decomposition of lead silicate and the formation of calcium-containing compounds, but under such conditions, the activity of ZnO will decrease.

Sun et al. [Contribution 3] contributed a paper entitled ‘A Model for Direct Effect of Graphene on Mechanical Property of Al Matrix Composite’. As is well-known, metal matrix composites (MMCs) can be improved by various reinforcements, and significant of efforts have been undertaken to characterize the mechanical behavior of particle-reinforced MMCs. The direct effect of graphene on the mechanical properties of AI matrix composites has been studied using molecular dynamic (MD) methods. Structural analysis of these composites indicates the increment of GNSs can promote the densification of metal matrices, increase the porosity of composites, and restrict metal grain size. In light of its crack propagation path, the stress–strain curve, and the distribution of stress, it can be concluded that graphene has not served effectively in the role of load transfer. Therefore, the direct strengthening of graphene is believed to have little impact on the mechanical properties of MMCs.

Wu et al. [Contribution 4] contributed a paper entitled ‘Digital Twin Design of a Turbulence Inhibitor in a Tundish Based on the Production Cluster Mining Algorithm’. The lack of a direct and linear relationship between inclusion removal from tundishes and the design of their turbulence inhibitors is a difficult challenge. This study used the inclusion/flow field database production clustering mining algorithm to conduct step-by-step data mining on the tundish flow field; to produce relevant facts regarding the flow field characteristics in the inclusion aggregation zone; and to extract the data mining results from the fact database to screen a digital twin algorithm that forecasts the inclusion aggregation area in a tundish to optimize the flow control device. The turbulence inhibitor designed by the digital twin method is currently being used in a Chinese steel mill.

Li et al. [Contribution 5] contributed a paper entitled ‘An Analysis of Long-Process Ironmaking in a Reduction Smelting Furnace with Hydrogen-Enriched Conditions’. With the approach of the “dual carbon” target, the iron and steel industry needs to transform and upgrade to “green” and “low-carbon” practices. A new ironmaking system and a method for a reduction smelting furnace (RSF) with Hy-O-CR is presented in this paper. The ironmaking system includes nine sets of equipment, such as an RSF, a gas dust collector, a dryer, a CO₂ separator, an electrolytic water device, a blower, a heat exchanger, a storage tank for reduction gas, and a chimney. By redesigning the size of the furnace and optimizing its parameters, the metallization rate of the indirect reduction zone can be as high as 85–95%, and the carbon consumption per ton of hot metal can be greatly reduced. By using oxygen to recycle the reduction gas produced by this reactor, the process achieves the goal of reducing CO₂ emissions by more than 50%, thus realizing green and low-carbon metallurgy.

Liu et al. [Contribution 6] contributed a paper entitled ‘Simulation and Validation of Thickness of Slag Crust on the Copper Stave in the High-Temperature Area of Blast Furnace’. The formation and thickness of the hot-surface slag crust on the copper stave in the high-temperature area of the middle and lower parts of the blast furnace are crucial for the safe operation and long service life of the blast furnace. To enhance the precision of measurements to determine the thickness of the slag crust in this specific region, samples were extracted from the hot surface of the copper cooler situated in the high-temperature area. This extraction was carried out during a maintenance procedure for the blast furnace stockline. The findings indicate that the blast furnace’s operation indices improved with a thinner slag crust, but there was also a higher chance of damage to the copper stave’s internal cooling water pipes. Taking into account the technical and economic indices as well as the long service life of the blast furnace, 150–200 mm is recommended as the appropriate average slag crust thickness on the surface of the copper stave in the high-temperature section.

Khajezade et al. [Contribution 7] contributed a paper entitled ‘Large-Scale Multi-Phase-Field Simulation of 2D Subgrain Growth’. The characteristics of subgrains in a deformed state after the high-temperature deformation of aluminum alloys control the subsequent recrystallization process and the corresponding mechanical properties. In this study, systematic 2D phase-field simulations were conducted to determine the role of the parameters of the deformed state. The results of these simulations indicate that the growth of subgrains reaches a self-similar regime regardless of the initial subgrain structure. A narrower initial subgrain size distribution leads to faster growth rates, but it is the initial disorientation distribution that has a larger impact on the growth of subgrains.

Li et al. [Contribution 8] contributed a paper entitled ‘Analysis of Technological Pathways and Development Suggestions for Blast Furnace Low-Carbon Ironmaking’. Given the urgent need for carbon reduction, the exploration of low-carbon pathways in blast furnace (BF) metallurgy emerges as crucial. Evaluating both asset retention and technological maturity, the development of low-carbon technologies for BFs represents the most direct and effective technical approach. This article innovatively proposes a comprehensive low-carbon metallurgical process concept with the substitution of carbon-neutral biomass fuels at the source stage, the intensification of hydrogen enrichment in the process stage, and the fixation of CCUS at the end stage (SS-IP-FE). This process integrates the cleanliness of biomass, the high efficiency of hydrogen enrichment, and the thoroughness of carbon fixation through CCUS, synergistically enhancing overall effectiveness. This integrated strategy holds promise for achieving a 50% reduction in carbon emissions from BFs in the long term.

Myrzakulov et al. [Contribution 9] presented a study entitled “Analysis of the Effect of Fluxing Additives in the Production of Titanium Slags in Laboratory Conditions”; they provided a theoretical foundation and experimental validation for the feasibility of employing electric melting of Satbayevskiy ilmenite concentrates with novel fluxing additives. These additives are composed of oxides and nitrides derived from aluminum, calcium, and boron. The purpose of this work is to develop a technology for obtaining titanium slag that is suitable for the production of titanium sponge from the low-grade ilmenite concentrates of the Satbaevskoye deposit in Kazakhstan. The work uses an innovative approach, consisting of the use of new fluxing additives, which makes it possible to solve the problem of the inefficient processing of this raw material.

Zhang et al. [Contribution 10] contributed a paper entitled ‘Physical Simulation of Gas–Liquid Mass Transfer Behavior in Oxygen Bottom Blowing Copper Furnace’. In order to improve the internal chemical reaction efficiency of oxygen bottom-blowing copper smelting furnaces, an efficient separation and flow control device and a technology fpr matte and slag in such furnaces were put forward. The effect of variables related to the retaining wall device on the gas–liquid mass transfer behavior inside bottom-blown copper furnaces is described by developing a 1:9.3 water model. The effects of this retaining wall device on the efficiency of chemical reactions in the furnace at different insertion depths, horizontal distances, diameters of double guide holes, and gas flow rates were investigated, and empirical formulas were obtained.

3. Summary and Outlook