This work presents a semi-smelting reduction and magnetic separation process for the recovery of iron and alumina slag from iron rich bauxite ore. The effect of the process parameters on the recovery rate of iron, maximum particle size of the iron nugget, and the Al₂O₃ content of the alumina slag was investigated and optimized. The results show that the iron nuggets and alumina slag can be obtained in a short time through a semi-smelting reduction and magnetic separation process. The maximum particle size of iron nugget is about 15 mm, and the recovery rate of the iron and Al₂O₃ grade of the alumina slag are 96.84 wt % and 43.98 wt %, respectively. The alumina slag consisted mainly of alumina (α-Al₂O₃), calcium hexaluminate (CaAl₁₂O₁₉), gehlenite (Ca₂Al₂SiO₇), and small amounts of hercynite (FeAl₄O₇), and metallic iron (M.Fe).

Iron and steel industry is the pillar industry of the national economy, but it is also the source of highest carbon emission in manufacturing industry. With the proposal of China’s goal of peaking carbon emissions and achieving carbon neutrality, the steel industry urgently requires substantial technological breakthroughs in carbon reduction. About 90% of China’s crude steel production is produced through the blast furnace-basic oxygen furnace process, and blast furnace carbon consumption accounts for more than 70% of steel process carbon consumption. Therefore, blast furnace carbon reduction is the focal point of China’s steel industry’s efforts to mitigate carbon emissions. The hydrogen-rich gas injection to blast furnace and blast furnace with top gas recycling process are effective ways to reduce carbon emissions. However, these approaches still rely heavily on the fossil fuel coal-dominated energy structure. With the rapid development of renewable energy hydrogen production in China, hydrogen-rich oxygen blast furnace technology, which replaces carbon with hydrogen, can significantly reduce carbon emissions from ironmaking at the source. This article establishes a multizone constrained mathematical model for hydrogen-rich oxygen blast furnaces, calculates energy balance based on the constraint conditions of each zone, and systematically studies the influence of hydrogen injection, burden metallization rate on the coke ratio, top gas recycling injection volume, reducing gas composition, and CO ₂ emission reduction of hydrogen-rich oxygen blast furnaces. The research results show that at maximum hydrogen injection rate of about 600 N·m ³ H ₂ ·t ⁻¹ -HM (ton-hot metal), a replacement ratio of about 0.4 kg-coke·(N·m) ⁻³ -H ₂ was achieved with about 27% CO in the reduced gas of the shaft, 68% H ₂ , 90% burden metallization rate. Coke ratio of the hydrogen-rich oxygen blast furnace is reduced to 203 kg and the CO ₂ emission is reduced to 501 kg·t ⁻¹ -HM, 55% lower than that without hydrogen injection with a very significant CO ₂ reduction at the source.

Hydrogen-based direct reduction (H-DR) represents an environmentally benign and energy-efficient alternative in ironmaking that has significant industrial potential. This study reviews the current status of H-DR shaft furnaces and accompanying hydrogen-rich reforming technologies (steam and autothermal reforming), assessing the three dominant numerical frameworks used to analyze these processes: (i) porous medium continuum models, (ii) the Eulerian two-fluid model (TFMs), and (iii) coupled computational fluid dynamics (CFD)–discrete element method (DEM) models. The respective trade-offs in terms of computational cost and model accuracy are critically compared. Recent progress is evaluated from an engineering standpoint in four key areas: optimization of the pellet bed structure and gas distribution, thermal control of the reduction zone, sensitivity analysis of operating parameters, and industrial-scale model validation. Current limitations in predictive accuracy, computational efficiency, and plant-level transferability are identified, and possible mitigation strategies are discussed. Looking forward, high-fidelity multi-physics coupling, advanced mesoscale descriptions, AI-accelerated surrogate models, and rigorous uncertainty quantification can facilitate effective scalable and intelligent application of hydrogen-based shaft furnace simulations.

Bauxite is the main source for alumina production. With the rapid development of iron and steel industry and aluminum industry, high-quality iron ore and bauxite resources become increasingly tense. However, a lot of iron-rich bauxite and Bayer red mud resources have not been timely and effectively recycled, resulting in serious problems of environmental pollution and wastage of resources. The comprehensive utilization of iron-rich bauxite and red mud is still a worldwide problem. The industrial stockpiling is not a fundamental way to solve the problems of iron-rich bauxite and red mud. As to the recovery of valuable metals from iron-rich bauxite and red mud, there are a lot of technical and cost problems, which are serious impediments to industrial development. Applying red mud as construction materials like cement, soil ameliorant applications face the problem of Na, Cr, As leaching into the environment. However, the high-temperature reduction, smelting and alkaline leaching process is a feasible method to recover iron and alumina from iron-rich bauxite and red mud. This chapter intends to provide the reader an overview on comprehensive utilization technology of the low-grade iron-rich bauxite and Bayer red mud sources.

Vanadium–titanium magnetite (VTM) is an iron ore abundantly available in China. The dominant utilization route is blast furnace smelting; however, Ti in the ore deteriorates sinter strength, making it urgent to clarify Fe-Ti-Ca interactions during sintering. In this work, single-phase FeTiO₃ and Fe₂TiO₄ were synthesized and each paired with CaO to fabricate diffusion couples. The couples were heated at 1200 °C for 30, 60, 90, and 120 min to investigate their interdiffusion behaviors and microstructure recombination mechanisms. The results show that, at 1200 °C, solid-state diffusion—not interfacial reaction—controls mass transfer in both FeTiO₃-CaO and Fe₂TiO₄-CaO systems. Distinct Fe-rich and Ti-rich sublayers appear within the reaction zone, and banded CaTiO₃ forms adjacent to the FeTiO₃/Fe₂TiO₄ matrices. The interdiffusion coefficients were determined to be 4.08 × 10⁻¹⁰ cm²·s⁻¹ and 7.81 × 10⁻¹⁰ cm²·s⁻¹, and the growth of the reaction layer follows a parabolic law, which can be expressed as x² = 2 × 1.562 × 10⁻⁹ t and x² = 2 × 0.8159 × 10⁻⁹ t, respectively. The coefficients of determination exceed 0.90, indicating reliable regression fits.