Blaine specific surface area (SSA) is an essential physical property of iron concentrate and is availably improved by a high-pressure grinding roller (HPGR) to enhance the pelletability and the qualities of oxidized pellets. In this study, the four concentrates with various SSA were obtained by HPGR treatment to produce the oxidized pellets. The results show that the high degree of lattice deformation corresponds to high SSA which is beneficial for improving the quality of green, preheated, and fired pellets. The compressive strength increases from 600 to 1870 N·pellet⁻¹ for preheated pellets and increases from 2530 to 4270 N·pellet⁻¹ for fired pellets when SSA increased from 849 cm²/g to 1601 cm²/g, under the optimal condition of preheating at 1050 °C for 12 min and firing at 1250 °C for 15 min. The oxidation of magnetite is accelerated. Low porosity and microphotographs with integrated hematite joined crystallization support the strength enhancement by high SSA.

Extracting iron while minimizing the health and environmental risks associated with arsenic contamination necessitates the removal of arsenic from arsenic-bearing iron ores to ensure a safe and sustainable supply of this metal for industries. The beneficiation of iron minerals and arsenic-bearing minerals from arsenic-bearing iron ores with a calcification-magnetizing roasting and low-intensity magnetic separation (CMR-LMS) process is investigated in this work. The results show that the process is successful in extracting iron minerals and eliminating arsenic-containing minerals. The roasting involves two key steps: calcification and magnetizing, which change hematite and goethite into magnetite and arsenic-bearing minerals into calcium arsenates. The process’s separation efficiency of the CMR-LMS is closely linked to the parameters such as roasting temperature, roasting time, coke, alkalinity, and the liberation of gangue minerals from iron minerals. Through grinding and secondary magnetic separation, the iron minerals and gangue components, as well as arsenic, in roasted sand can be further separated. The optimum procedure results in a high-grade iron concentrate with an iron assay of 65.65%, an Fe recovery rate of 80.07%, and an arsenic content of 0.085%, while achieving a 93.29% As removal rate from the original ore that has 45.32% Fe and 0.70% As.

The quality of sintering ore and the efficiency of the blast furnace are both heavily dependent on the high-temperature performance and compatibility of iron ores. A novel characterization technique, the Assimilation Melt Breakover method, is proposed to test the electrical performance during assimilation in sintering. Utilizing the two-electrode method, the electrical resistance of mixtures of ferrite oxide and calcium oxide was measured during their assimilation. A rise in temperature is associated with a reduction in electrical resistance, adhering to the principles of Arrhenius Law. The changes in conductivity observed during the assimilation process accurately reflect the mineral phase transformations, encompassing alterations within the solid state and transitions from solid to melt. The transition is marked by a substantial reduction in electrical resistance, specifically from several thousand to a few dozen Ohms in melting assimilation, along with notable variations in the activation energy associated with conductance. This research has the potential to swiftly differentiate between the assimilation characteristics of different iron ores, as well as to assist in the utilization of an electric field in iron ore sintering.

Metallic iron (MFe) catalyzes the reduction of NO by CO in iron ore sintering, though the underlying mechanism remains insufficiently understood. This study proposes an innovative decoupling strategy that separates the coupled CO-NO reaction into distinct Fe–NO and FeOy-CO processes. Thermodynamic analyses of the Fe-C-O and Fe-N-O systems were performed using FactSage software, supplemented by fixed-bed experiments to identify key factors influencing the MFe-catalyzed CO-NO reaction. Kinetics were evaluated based on an equivalent particle model. The results demonstrate that MFe serve as the most effective catalyst for the CO-NO reaction. The MFe-NO reaction is self-terminating and exhibits a stage-dependent control mechanism: it is initially dominated by chemical reaction kinetics and later transitions to gas diffusion control. Significant diffusion resistance within the product layer is evidenced by an activation energy of 71.93 kJ/mol, which is 11.33 times that of the surface reaction activation energy of 6.35 kJ/mol. This indicates that the catalytic efficiency is limited by the dense surface structure of MFe. The addition of 3% MFe resulted in a 14.2% reduction in total NO emissions, offering a practical approach for achieving cleaner sintering operations.