{"title":"Iron Oxide Reduction Rate Affects Iron Product Morphology","authors":"Rafaela Rapalo, Petrus Christiaan Pistorius","doi":"10.1007/s11669-026-01262-2","DOIUrl":null,"url":null,"abstract":"<div><p>Magnetite concentrates from different parts of the Mesabi Range, exhibiting varying tendencies to encapsulate, were reduced using thermogravimetric analysis (TGA) and a high-temperature confocal scanning laser microscope (CSLM). Gas-phase mass-transfer conditions were intentionally varied by employing two reactors with different geometries: the TGA produced significantly slower reduction, whereas the CSLM setup yielded reduction rates up to 20 times faster under mass-transfer-controlled conditions. A preliminary mechanism is proposed to explain the transition from a porous iron product to a dense encapsulating layer. Encapsulation is interpreted as the outcome of competition between pore creation, driven by the reduction rate, and pore elimination, driven by surface diffusion. When pore formation is insufficient to counteract pore coarsening, a dense iron layer develops and restricts further reduction.</p></div>","PeriodicalId":657,"journal":{"name":"Journal of Phase Equilibria and Diffusion","volume":"47 Focus:","pages":"383 - 393"},"PeriodicalIF":2.0000,"publicationDate":"2026-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s11669-026-01262-2.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Phase Equilibria and Diffusion","FirstCategoryId":"88","ListUrlMain":"https://link.springer.com/article/10.1007/s11669-026-01262-2","RegionNum":4,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Magnetite concentrates from different parts of the Mesabi Range, exhibiting varying tendencies to encapsulate, were reduced using thermogravimetric analysis (TGA) and a high-temperature confocal scanning laser microscope (CSLM). Gas-phase mass-transfer conditions were intentionally varied by employing two reactors with different geometries: the TGA produced significantly slower reduction, whereas the CSLM setup yielded reduction rates up to 20 times faster under mass-transfer-controlled conditions. A preliminary mechanism is proposed to explain the transition from a porous iron product to a dense encapsulating layer. Encapsulation is interpreted as the outcome of competition between pore creation, driven by the reduction rate, and pore elimination, driven by surface diffusion. When pore formation is insufficient to counteract pore coarsening, a dense iron layer develops and restricts further reduction.
期刊介绍：
The most trusted journal for phase equilibria and thermodynamic research, ASM International''s Journal of Phase Equilibria and Diffusion features critical phase diagram evaluations on scientifically and industrially important alloy systems, authored by international experts.
The Journal of Phase Equilibria and Diffusion is critically reviewed and contains basic and applied research results, a survey of current literature and other pertinent articles. The journal covers the significance of diagrams as well as new research techniques, equipment, data evaluation, nomenclature, presentation and other aspects of phase diagram preparation and use.
Content includes information on phenomena such as kinetic control of equilibrium, coherency effects, impurity effects, and thermodynamic and crystallographic characteristics. The journal updates systems previously published in the Bulletin of Alloy Phase Diagrams as new data are discovered.
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