During peritectic steel continuous casting, mold flux properties and flux film structures play significant roles in controlling slab quality. In this study, mold fluxes and flux films for casting peritectic steel slab were obtained using mineral raw materials such as quartz, wollastonite, fluorite, soda ash and others. The effects of mineral raw materials on mold flux properties and flux film structures were investigated through the measurement of melting point, viscosity, crystallization temperature, critical cooling rate, crystallization ratio and crystalline phase content. The results indicated that with increasing the quartz addition (16 to 24 mass%) and the wollastonite addition (11 to 19 mass%) in mineral raw materials, the melting point, viscosity and wollastonite content of flux film increased, while the crystallization temperature, critical cooling rate, crystallization ratio and cuspidine content of flux film decreased. The melting point, viscosity and wollastonite content of flux film reduced with increasing the fluorite addition (8 to 16 mass%) and soda ash addition (10 to 18 mass%) in mineral raw materials. Furthermore, compared with soda ash, the fluorite predominantly enhanced the crystallization temperature, critical cooling rate, crystallization ratio, cuspidine content of flux film. In addition, it was showed that the heat transfer performance and the slab quality might be primarily attribute to the crystallization ratio and cuspidine content of flux film. These results provided a theoretical foundation for optimizing the mold flux of the peritectic steel and were vital to improving the slab quality.

To meet the demanding requirements of continuous casting for low-alloy peritectic steel, this study aimed to design high-performance mold fluxes with optimized properties. The melting properties, crystallization behavior, mineralogical characteristics, and heat transfer mechanism of the industrial mold fluxes and flux films were investigated by melting tester, viscometer, in situ thermal analyzer, thermal conductivity meter, polarizing microscope, X-ray diffraction, and thermodynamic software. The results demonstrate that mold fluxes suitable for low-alloy peritectic steel possess a narrow melting temperature range, low melting point (<1200 °C), and low viscosity (50 °C/s) and high initial crystallization temperature (>1350 °C), facilitating the rapid formation of a stable crystalline layer and uniform heat transfer. The flux films with outstanding characteristics have a multilayered structure and high crystallization ratio (60–80 vol%), predominantly comprising a high fraction of coarsened cuspidine crystals. Further analysis of the heat transfer mechanism reveals that the highly crystalline and coarse-grained microstructure promotes the formation of micropores and crystal boundaries in flux films, which substantially increase thermal resistance, leading to low thermal conductivity (0.47–0.67 W/m·K) and effective control of heat transfer rate. It is concluded that enhancing crystallization performance through optimizing flux composition (boosting Na₂O content and basicity) to promote cuspidine formation and tailor crystallinity, is the crucial route for acquiring the desired mineralogical structure of flux films and enabling efficient continuous casting of low-alloy peritectic steel.

The degree of homogeneity of the sintered ore phase structure directly determines its quality index. A sinter ore quality evaluation method based on the quantification of the homogeneity of the mineral phase structure is proposed. First, the magnetite particle size characteristics in the ore phase structures with different degrees of homogeneity were summarized under a polarized light microscope, and a criterion for evaluating the uniformity of the sintered ore phase structure based on the magnetite content of different particle size grades was determined. Second, a multiple regression model was established for the raw material composition ratio of magnetite with varying particle size grades. Finally, the multiple regression model was optimized using the second-generation non-dominated sorting genetic algorithm (NSGA2). The results show that mineral phase structure analysis categorized the magnetite particle sizes into 60 μm. The adjusted R² of the multiple regression model of the chemical composition of raw materials and the proportion of magnetite of each particle size grade were all greater than 0.95, and the p values were all <0.05, indicating a high degree of model fitting. Using model analysis, the single factor and the interaction between the multiple factors that significantly influence the proportion of magnetite in the three particle size grades were determined. The multivariate regression model was optimized using the NSGA2 algorithm to determine the ratios of Al₂O₃ mass% = 1.82, MgO mass% = 1.50, and R(CaO mass%/SiO₂ mass%) = 1.84 for the highest degree of uniformity of the sintered ores. Under this sintering condition, the micro-mineral phase structure became more homogeneous, confirming the model’s reliability.

Coal gangue (CG), a bulk solid waste produced during coal mining, is rich in active components such as silicon and aluminum oxides, making it a high-quality raw material for the production of cementitious materials. Its utilization represents a significant pathway for achieving high-value applications of CG and facilitating the low-carbon transformation of the cement industry. Owing to advantages such as low carbon emissions, environmental friendliness, cost-effectiveness, and tunable performance, CG-based cementitious materials have been extensively investigated by researchers worldwide. Studies have focused on various aspects, including cementitious backfill materials, CG solid waste-based cement, geopolymers, concrete, and composite materials derived from CG. This paper systematically reviews the regional distribution, mineral composition, chemical constituents, and reactivity characteristics of CG. It further summarizes recent advances in activation techniques, performance optimization, and engineering applications of CG-based cementitious materials. Current challenges, such as insufficient activation efficiency, ambiguous hydration mechanisms, and limitations in large-scale application, are critically analyzed. Finally, future research directions and development trends are outlined to provide a theoretical foundation for further investigation and industrial implementation of CG-based cementitious materials.