Effect of Gas Composition on the Carbothermic Reduction of Manganese Oxide.

Yastreboff, M.; Ostrovski, Oleg; Ganguly, Samir

doi:10.2355/isijinternational.43.161

Cited by 43 publications

(47 citation statements)

References 3 publications

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“…[10,11] It was established that the rate of carbothermal reduction of manganese ore is faster in helium than in argon [10,11] and faster in hydrogen than in helium. [11] This was explained by the higher diffusion coefficient of CO in helium and hydrogen in comparison with argon (by a factor of 4) and by involvement of hydrogen in the reduction process.…”

Section: Carbothermal Reduction Of Titania In Different Gas Atmosphermentioning

confidence: 99%

Carbothermal Reduction of Titania in Different Gas Atmospheres

Dewan

Zhang

Ostrovski

2008

Metall Mater Trans B

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The synthesis of titanium oxycarbide by carbothermal reduction of titania was studied in hydrogen, argon, and helium in isothermal and temperature programmed reduction experiments in a tube reactor with continuously flowing gas. In the temperature range of 1000°C to 1500°C, the reduction rate increased with increasing temperature. Formation of titanium oxycarbide started at 1200°C in all three gases. The reduction was the fastest in hydrogen. Formation of titanium oxycarbide in hydrogen was close to completion in 120 minutes at 1300°C, 60 minutes at 1400°C, and less than 30 minutes at 1500°C. The reduction in argon and helium had similar rates and reached 90 to 95 pct after a 300-minute reduction at 1400°C to 1500°C. Faster carbothermal reduction of titania in hydrogen than in argon and helium was attributed to involvement of hydrogen in the reaction. Hydrogen reduced titania to titanium suboxides and reacted with carbon, forming methane, which reduced titanium suboxides to titanium oxycarbide. Titanium oxycarbide synthesized in hydrogen for 180 minutes at 1300°C contained 13 mol pct TiO. At 1500°C, oxygen concentration decreased to a degree corresponding to 1.4 mol pct TiO. In the titanium oxycarbide produced by a 300-minute reduction at 1600°C, the TiO content was 0.6 mol pct.

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Section: Carbothermal Reduction Of Titania In Different Gas Atmosphermentioning

confidence: 99%

Carbothermal Reduction of Titania in Different Gas Atmospheres

Dewan

Zhang

Ostrovski

2008

Metall Mater Trans B

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“…Hence, it has been proposed that the carbothermic reduction of MnO is a mixed-control reaction that controls both the chemical reaction and the CO mass transfer in the gas phase. [12] The mechanism of MnO reduction from low and high MnO containing slags by the dissolved carbon in liquid iron is also well known. [3,5,6,10] According to this mechanism, MnO is reduced by Fe at the slag/metal interface and Mn and FeO are produced.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10][11][12] These studies have been mainly conducted in graphite crucibles with or without an initial metal phase. Stirring has no significant effect on the kinetics of MnO reduction, whereas the reduction rate is affected by the slag composition and temperature.…”

Section: Introductionmentioning

confidence: 99%

Kinetics and Mechanism of the Simultaneous Carbothermic Reduction of FeO and MnO from High-Carbon Ferromanganese Slag

Safarian

Kolbeinsen

Tangstad

et al. 2009

Metall Mater Trans B

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The carbothermic reduction of 38.7 pct MnO-12.1 pct pct MgO-9.3 pct Al 2 O 3 -24.1 pct SiO 2 -10.4 pct FeO slag in Ar at 1600°C was studied using the sessile drop wettability technique. Pure graphite, coke, and charcoal were used as the carbon material substrates. The reduction rates were evaluated by sampling at different reduction times and by analyzing the chemical compositions of the reduced slag and the produced metal. The carbothermic FeO reduction from slag is initially fast followed by a much slower reduction rate. However, the rate of the MnO reduction is slow in the fast FeO reduction stage, and it starts to increase significantly during the slow FeO reduction stage. The kinetics of FeO and MnO reduction are affected by the type of carbonaceous materials. Moreover, the rate of the carbon dissolution/transfer into the produced metal phase and the amount of the transferred manganese to the metal phase depend on the type of carbon. Based on the experimental observations and the thermodynamic calculations, a mechanism for MnO reduction was proposed. According to this mechanism, MnO is mainly reduced through a metallothermic reduction by Fe and the rate of MnO reduction is controlled by the rate of the consumption of FeO from the slag, which takes place simultaneously. In contrast, the rate of FeO reduction in the fast initial reduction stage is controlled by the rate of the carbon dissolution/transfer into the metal phase. However, at the second slow FeO reduction stage, it is reduced mainly by the solid carbon.

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“…Authors of works 3,5,[7][8][9][10][11][12] concluded that lowering CO partial pressure increases both the rate and extent of reduction. The fastest rate of carbothermal manganese ore reduction was achieved in inert atmosphere.…”

Section: Introductionmentioning

confidence: 99%