Use of H2 in Mn-Ferroalloy Production

Tangstad, Merete; Schanche, Trygve Lindahl; Preez, Faan de

doi:10.1007/978-3-031-22634-2_4

Cited by 5 publications

(1 citation statement)

References 9 publications

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“…Though the implementation of hydrogen in the reduction of metal oxides is many years from maturing, the use thereof in Fe-ore (ores comprising mainly of Fe-oxides) smelting and the steel industry has advanced significantly in many developed countries [125][126][127][128][129][130][131]. Additionally, hydrogen has shown potential as a pre-reductant in the ferromanganese industry, metalizing Fe-oxides, reducing higher Mn-oxides to lower oxidation states [132][133][134][135][136], and having an effect on the reaction rates and mechanisms during Si processing [137,138]. More so, using hydrogen to produce fossil-free Fe is currently a major focus in Europe as a means of decarbonizing the industry [139,140].…”

Section: Hydrogen As a Reductantmentioning

confidence: 99%

An Overview of Currently Applied Ferrochrome Production Processes and Their Waste Management Practices

du Preez,

van Kaam,

Ringdalen

et al. 2023

Minerals

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Ferrochrome (FeCr) is the main source of virgin chromium (Cr) units used in modern-day chromium (Cr) containing alloys. The vast majority of produced Cr is used during the production of stainless steel, which owes its corrosion resistance mainly to the presence of Cr. In turn, stainless steel is mainly produced from Cr-containing scrap metal and FeCr, which is a relatively crude alloy between iron (Fe) and Cr. The production of FeCr is an energy and material-intensive process, and a relatively wide variety of by-products, typically classified as waste materials by the FeCr industry, are created during FeCr production. The type and extent of waste generation are dictated by the smelting route used and the management practices thereof employed by a specific smelter. In some cases, waste management of hazardous and non-hazardous materials may be classified as insufficient. Hazardous materials, such as hexavalent Cr, i.e., Cr(VI), -containing wastes, are only partially mitigated. Additionally, energy-containing wastes, such as carbon monoxide (CO)-rich off-gas, are typically discarded, and energy-invested materials, such as fine oxidative sintered chromite, are either stockpiled or sold as ordinary chromite. In cases where low-value containing wastes are generated, such as rejects from ore beneficiation processes, consistent and efficient processes are either difficult to employ or the return on investment of such processes is not economically viable. More so, the development of less carbon (C)-intensive (e.g., partial replacement of C reductants) and low-temperature pellet curing processes are currently not considered by the South African FeCr smelting industry. The reasoning for this is mainly due to increased operation costs (if improved waste management were to be implemented/higher cost reductants were used) and a lack of research initiatives. These reasons result in the stagnation of technologies. From an environmental point of view, smelting industries are pressured to reduce C emissions. An attractive approach for removing oxygen from the target metal oxides, and the mitigation of gaseous C, is by using hydrogen as a reductant. By doing so, water vapor is the only by-product. It is however expected that stable metal oxides, such as the Cr-oxide present in chromite, will be significantly more resistive to gaseous hydrogen-based reduction when compared to Fe-oxides. In this review, the various processes currently used by the South African FeCr industry are summarized in detail, and the waste materials per process step are identified. The limitations of current waste management regimes and possible alternative routes are discussed where applicable. Various management regimes are identified that could be improved, i.e., by utilizing the energy associated with CO-rich off-gas combustion, employing a low-temperature alternative chromite pelletization process, and considering the potential of hydrogen as a chromite reductant. These identified regimes are discussed in further detail, and alterative processes/approaches to waste management are proposed.

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Section: Hydrogen As a Reductantmentioning

confidence: 99%

An Overview of Currently Applied Ferrochrome Production Processes and Their Waste Management Practices

du Preez,

van Kaam,

Ringdalen

et al. 2023

Minerals

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Evaluating the Reaction Kinetics on the H2 Reduction of a Manganese Ore at Elevated Temperatures

Sarkar,

Schanche,

Wallin

et al. 2024

J. Sustain. Metall.

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This study investigates the hydrogen reduction of Nchwaning manganese ore at elevated temperatures to enhance understanding of reaction kinetics and optimize industrial applications. Experimental investigations were conducted across temperatures ranging from 600 °C to 900 °C to observe reduction behavior and identify rate determining steps. Thermogravimetric analysis (TGA) was employed to monitor manganese ore weight loss, facilitating precise measurement of reduction rates. Various kinetic models validated experimental outcomes for H2 reduction, revealing an apparent activation energy (Ea) of 65.76 kJ/mol and an apparent pre-exponential factor (k0) of 319.66 min⁻1. The rate constant (k) exhibited a significant temperature-dependent increase, following the Arrhenius equation where rates approximately doubled every 100 °C, rising from 0.037 min⁻1 at 600 °C to 0.377 min⁻1 at 900 °C. Morphological and compositional analyses using scanning electron microscopy (SEM) and X-ray diffraction (XRD) assessed structural changes post-reduction. Results demonstrated that pre-reduction temperature critically influences the physical and microstructural properties of the ore particles, particularly above 700 °C, where a notable reduction in BET (Brunauer–Emmett–Teller) surface area and pore volume indicated sintering within the ore. The rate determining step for this reduction process is most likely the chemical reaction at the gas–solid interface between hydrogen and the manganese ore. These findings highlight advancements in efficient manganese ore reduction processes, with significant implications for metallurgical practices and the hydrogen economy. Graphical Abstract

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Reducing Co2 Emissions and Decarbonization Costs in Manganese Production by Integrating Fuel-Assisted Solid Oxide Electrolysis Cells in 2-Stage Oxide Reduction

Nielsen,

del Alamo,

Schanche

et al. 2024

Preprint

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Use of H2 in Mn-Ferroalloy Production

Cited by 5 publications

References 9 publications

An Overview of Currently Applied Ferrochrome Production Processes and Their Waste Management Practices

An Overview of Currently Applied Ferrochrome Production Processes and Their Waste Management Practices

Evaluating the Reaction Kinetics on the H2 Reduction of a Manganese Ore at Elevated Temperatures

Reducing Co2 Emissions and Decarbonization Costs in Manganese Production by Integrating Fuel-Assisted Solid Oxide Electrolysis Cells in 2-Stage Oxide Reduction

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