Mechanism of Ion-Diffusion Solid-Phase Reduction of Iron Oxides of Technogenic Origin in the Presence of the Liquid Phase and without it

Sheshukov, O. Yu.; Михеенков, М. А.; Vedmid, L. B.; Nekrasov, I. V.; Egiazar’yan, D. K.

doi:10.3390/met10121564

Cited by 10 publications

(12 citation statements)

References 13 publications

(22 reference statements)

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“…This cementite reacts with carbon dioxide (generated in step I) following Eq. ( 5) [10]. In this step, fewer gases than in the previous step would be formed, which is reflected in a lesser mass loss.…”

Section: Resultsmentioning

confidence: 99%

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Carbothermal reduction of mill scales formed on steel billets during continuous casting

et al. 2021

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A billet is a bar made from crude steel which surface contains scales which are rich in iron oxides. This study presents the carbothermal reduction of the scales formed in steel billets. The process included the reaction of the iron oxides contents with carbon (in ratio 5:1) and annealing in a tubular furnace under argon atmosphere. The occurred reactions are discussed using thermodynamic calculations and thermal analysis which indicate a three-stage reduction process Fe3O4 ➔ FeO ➔ Fe3C ➔α-Fe with intermediate reactions at the interval temperature 960 and 1300 °C. The X-ray diffraction confirms the reduction to α-Fe with minor presence of unreacted C, magnetite and wustite. Mössbauer spectroscopy analysis was performed at room temperature where a typical sextet corresponding to the dominant α-Fe is shown as well as wustite, magnetite and cementite to a lesser extent. The magnetization measurements confirm the ferromagnetic state corresponding to the α-Fe.

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Section: Resultsmentioning

confidence: 99%

“…This process is accompanied with gasification of carbon via the Boudouard reaction which promotes the sudden mass loss through Eq. ( 3) [4,10]. This reaction controls the overall process of the reduction.…”

Section: Calculation Of the Gibbs Free Energymentioning

confidence: 99%

Carbothermal reduction of mill scales formed on steel billets during continuous casting

et al. 2021

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“…It is established that the reduction proceeds in the sequence Fe 3 O 4 -FeO-Fe 3 C-α-Fe. In [ 5 ], the MCA influence (the briquetting pressure of the initial reagents) on the reduction in kinetics of scale of iron oxides during heating is considered. It was found that the reduction of iron oxides in scale proceeds in a solid-phase manner in three modes: diffusion-free, intermediate and diffusion.…”

Section: Introductionmentioning

confidence: 99%

“…In [ 5 ], only one of the MCA methods was considered (pressing). However, preliminary grinding is important for scale secondary processing.…”

Section: Introductionmentioning

confidence: 99%

“…To explain the effects observed during the scale iron oxide reduction, an ion-diffusion-catalytic mechanism of solid-phase technogenic (scale) iron oxide reduction was proposed in [ 5 ]. In accordance with this mechanism, at the first stage there is a solid-phase interaction of hematite located on the scale surface with solid carbon located in the intergranular space, with the formation of CO according to Equation (2): Fe 2 O 3 + C = 2FeO + CO↑ …”

Section: Introductionmentioning

confidence: 99%

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Mechanochemical Activation Effect on Technogenic Iron Oxide Reduction Kinetics

et al. 2022

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Understanding the reaction kinetics of iron oxide reduction by carbon is a key task of the theory of metallurgical processes. One of the understudied features of the reaction kinetics of iron oxide solid-phase reduction by carbon is the discrepancy between the reacting substances’ small contact area and the process’s high rate. A convincing theoretical and experimental explanation of this effect has not yet been obtained. The data obtained earlier show that an increase in the scale of the briquetting pressure from 0 to 300 MPa increases the degree of its metallization during heating two-fold, and the metallization temperature decreases by more than 40 °C. Therefore, it was assumed that these effects during heating are a consequence of the mechanochemical activation (MCA) of iron oxides in the scale during its pressing. This paper presents the results of experimental studies on the influence of two types of scale MCA (grinding and pressing) on iron oxide reduction. The study of the MCA effect on the reaction kinetics of scale iron oxide reduction by carbon is a promising way to assess the criteria for scale phase composition changes under external factors. The presented results indicate a decrease in the amount of trivalent iron oxide (Fe2O3) after the MCA and an increase in the amount of one-and-a-half oxide (Fe3O4) and bivalent iron oxide (FeO). The obtained experimental data show that the initial stage of iron oxide reduction, consisting in the transition from higher iron oxides to lower ones, is possible at room temperature without carbon presence.

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Characterization of black slags obtained during smelting in the electric arc furnace from SIDERPERU following reduction

et al. 2022

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The primary process in an electrical arc furnace (EAF) during industrial steelmaking results in tons of black slags which cause pollution to the environment. In this work, the iron oxides of black slags generated in the EAF from the SIDERPERU plant, Peru was reduced via the carbothermal reaction. The reduction of the black slag to α-Fe is demonstrated by X-ray diffraction, Mӧssbauer spectroscopy and magnetometry. However, phases with calcium and silicon persist in the sample after the carbothermal process. The thermodynamic calculations of the most probable reactions sequence were performed to understand the reduction process. The magnetometry measurements confirm the presence of ferromagnetic domains, supporting the success of the reduction of the black slag to α-Fe. The reduced black slags were recycled into a HRB335 steel rod by consolidation and extrusion processes and inspected by X-ray fluorescence.

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Mechanism of Ion-Diffusion Solid-Phase Reduction of Iron Oxides of Technogenic Origin in the Presence of the Liquid Phase and without it

Cited by 10 publications

References 13 publications

Carbothermal reduction of mill scales formed on steel billets during continuous casting

Carbothermal reduction of mill scales formed on steel billets during continuous casting

Mechanochemical Activation Effect on Technogenic Iron Oxide Reduction Kinetics

Characterization of black slags obtained during smelting in the electric arc furnace from SIDERPERU following reduction

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