Phase Development in Carbothermal Reduction of Ilmenite Concentrates and Synthetic Rutile

Dewan, Mohammad A; Zhang, Guangqing; Ostrovski, Oleg

doi:10.2355/isijinternational.50.647

Cited by 35 publications

(23 citation statements)

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“…Reduction behaviour of ilmenites of different grades was similar to that observed in the synthesis of titanium oxycarbide by carbothermal reduction of ilmenites in hydrogen and helium [11]. The reduction rate increased with decreasing ilmenite grade in the reduction in the H 2 or in H 2 -N 2 gas mixture, and reduction rate decreased with decreasing ilmenite grade when reduction was in inert gas atmosphere or in nitrogen.…”

Section: Discussionsupporting

confidence: 51%

“…Difference in the reduction of ilmenites of different grades was attributed to differences in iron content and morphology. Optical and SEM analyses showed [11] that ilmenite concentrate of a higher grade had a higher porosity as a result of ilmenite weathering. The degree of weathering and particle porosity were the highest for synthetic rutile and lowest for primary ilmenite.…”

Section: Discussionmentioning

confidence: 99%

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Phase Development in Carbothermal Reduction and Nitridation of Ilmenite Concentrates

Rezan

Zhang

Ostrovski³

2012

High Temperature Materials and Processes

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Abstract:The phase development in the course of carbothermal reduction and nitridation of ilmentie concentrates and synthetic rutile was studied in temperature programmed reduction (623-1873 K) and isothermal reduction experiments. Ilmenites and synthetic rutile were reduced in a tube reactor with continuously flowing hydrogennitrogen mixture or pure nitrogen. The rate and extent of reduction were monitored by online off-gas analysis. Samples reduced to different extent were subjected to XRD and SEM/BSE analyses. Pseudorutile and ilmenite were the main phases in ilmenite concentrates; rutile was the main phase in synthetic rutile. Pseudorutile was first converted to ilmenite and titania which occurred at temperatures below 623 K; iron oxides in ilmenite were quickly reduced to metallic iron. Titania was reduced to titanium suboxides and further to titanium oxycarbonitride. Reduction of ilmenites and synthetic rutile in hydrogen-nitrogen mixture was much faster than in pure nitrogen. The rate of conversion of titanium oxides to oxycarbonitride was affected by iron content in the ilmenites. The rate of reduction increased with increasing iron content in ilmenite (decreasing grade) when ilmenites were reduced in the hydrogen-nitrogen gas mixture, but decreased with decreasing ilmenite grade in reduction experiments in nitrogen; reduction in nitrogen was the fastest for synthetic rutile. The difference in the reduction behaviour was attributed to different chemical compositions and morphologies of ilmenites of different grades.

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Section: Discussionsupporting

confidence: 51%

Section: Discussionmentioning

confidence: 99%

Phase Development in Carbothermal Reduction and Nitridation of Ilmenite Concentrates

Rezan

Zhang

Ostrovski³

2012

High Temperature Materials and Processes

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“…Dewan et al [3][4][5] investigated the synthesis of titanium oxycarbide by carbothermal reduction of titania and ilmenite concentrates in different gas atmospheres. The conversion of titania to titanium carbide was the fastest in hydrogen and can be implemented at lower temperatures compared with a reduction in inert gas.…”

Section: Introductionmentioning

confidence: 99%

Effect of Gas Atmosphere on Carbothermal Reduction and Nitridation of Titanium Dioxide

Rezan

Zhang

Ostrovski

2011

Metall Mater Trans B

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This article examined the reduction/nitridation of rutile in the He-N 2 , Ar-N 2 , and He (Ar)-H 2 -N 2 gas mixtures, as well as pure nitrogen, in the temperature-programmed and isothermal experiments in a fixed-bed reactor. The extents of reduction and nitridation were determined from the off gas composition and LECO analysis. The off-gas composition was monitored using the infrared sensor (CO, CO 2 , and CH 4 ) and dew point analyzer (H 2 O). The phase composition of the reduced samples was analyzed using X-ray diffraction (XRD). The temperature and gas composition had a strong effect on the rutile reduction. The reduction was the fastest in the H 2 -N 2 gas mixture, followed by a reduction in nitrogen; the rate of reduction/nitridation in the He-N 2 gas mixture was marginally higher than in the Ar-N 2 gas. The rate of titania reduction/ nitridation in the He (Ar)-H 2 -N 2 gas increased with the replacement of He (Ar) with hydrogen.

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“…[8][9][10][11] It was shown that gas atmosphere had a significant effect on the rate of reaction. Conversion of rutile to titanium oxycarbonitride occurred at lower temperature and higher rate in comparison with production of oxycarbide.…”

Section: Introductionmentioning

confidence: 99%

Carbothermal Reduction and Nitridation of Ilmenite Concentrates

2012

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Carbothermal reduction and nitridation of ilmenite concentrates of different grades and synthetic rutile were studied in isothermal experiments in hydrogen -nitrogen gas atmosphere and pure nitrogen in a tube reactor. Concentrations of CO and CO2 in the off gas were measured online using infrared gas analyser. The reaction products were analysed by X-ray diffraction. Iron oxides in ilmenite concentrates were reduced to metallic iron, and titanium oxides were converted to titanium oxycarbonitride. Reduction of ilmenite concentrates and synthetic rutile in hydrogen containing gas was significantly faster than in pure nitrogen. The rate of conversion of titania to titanium oxycarbonitride in the 50 vol% H2-50 vol% N2 gas mixture decreased with increasing grade of ilmenite concentrate. In nitrogen, reduction of synthetic rutile was faster than reduction of ilmenite concentrates.

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Phase Development in Carbothermal Reduction of Ilmenite Concentrates and Synthetic Rutile

Cited by 35 publications

References 10 publications

Phase Development in Carbothermal Reduction and Nitridation of Ilmenite Concentrates

Phase Development in Carbothermal Reduction and Nitridation of Ilmenite Concentrates

Effect of Gas Atmosphere on Carbothermal Reduction and Nitridation of Titanium Dioxide

Carbothermal Reduction and Nitridation of Ilmenite Concentrates

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