The reduction of iron oxides by volatiles in a rotary hearth furnace process: Part I. The role and kinetics of volatile reduction

Sohn, In Sook; Fruehan, R. J.

doi:10.1007/s11663-005-0051-y

Cited by 50 publications

(36 citation statements)

References 7 publications

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“…It was widely assumed that the metal oxides reduction by carbon should be negligible at temperatures lower than 1000 ºC [367][368][369]. However, Siriwardane et al [227,370] showed the direct reduction Even though N 2 was used as fluidizing gas, eventually the char conversion through CO 2 gasification can be the relevant reacting mechanism.…”

Section: Reaction Schemementioning

confidence: 99%

Progress in Chemical-Looping Combustion and Reforming technologies

Adánez

Abad

Garcı́a-Labiano

et al. 2012

Progress in Energy and Combustion Science

1,999

1,614

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This work is a comprehensive review of the Chemical-Looping Combustion (CLC) and Chemical-Looping Reforming (CLR) processes reporting the main advances in these technologies up to 2010. These processes are based on the transfer of the oxygen from air to the fuel by means of a solid oxygen-carrier avoiding direct contact between fuel and air for different final purposes. CLC has arisen during last years as a very promising combustion technology for power plants and industrial applications with inherent CO 2 capture which avoids the energetic penalty present in other competing technologies.CLR uses the chemical looping cycles for H 2 production with additional advantages if CO 2 capture is also considered.The review compiles the main milestones reached during last years in the development of these technologies regarding the use of gaseous or solid fuels, the oxygen-carrier development, the continuous operation experience, and modelling at several scales. Up to 2010, more than 700 different materials based on Ni, Cu, Fe, Mn, Co, as well as other mixed oxides and low cost materials, have been compiled. Especial emphasis has been done in those oxygen-carriers tested under continuous operation in Chemical-Looping 2 prototypes. The total time of operational experience (≈ 3500 h) in different CLC units in the size range 0.3-120 kW th , has allowed to demonstrate the technology and to gain in maturity. To help in the design, optimization, and scale-up of the CLC process, modelling work is also reviewed. Different levels of modelling have been accomplished, including fundamentals of the gas-solid reactions in the oxygen-carriers, modelling of the air-and fuel-reactors, and integration of the CLC systems in the power plant. Considering the great advances reached up to date in a very short period of time, it can be said that CLC and CLR are very promising technologies within the framework of the CO 2 capture options.

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Section: Reaction Schemementioning

confidence: 99%

Progress in Chemical-Looping Combustion and Reforming technologies

Adánez

Abad

Garcı́a-Labiano

et al. 2012

Progress in Energy and Combustion Science

1,999

1,614

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“…Furthermore, many studies on the reduction of iron ores by gas were reported. [17][18][19][20][21] The Bama ilmenite has abundant reserves in Guangxi province of China. However, the kinetics of reduction of the Bama ilmenite with hydrogen is unclear.…”

Section: Introductionmentioning

confidence: 99%

Reduction Extraction Kinetics of Titania and Iron from an Ilmenite by H2–Ar Gas Mixtures

et al. 2009

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Reduction of an ilmenite concentrate as a natural concentration containing 49.78 mass% TiO 2 and 27.96 mass% total Fe by H 2 -Ar gas mixtures was investigated from 1 073 to 1 273 K. Both the reduction degree and reduction rate increased with the increase of temperature and hydrogen content. The reduction degree of the ilmenite decreased due to the presence of impurities including manganese and silicon oxides in the ilmenite concentrate. During the reduction, the formation of manganese and silicon oxide-enriched zones prevented complete reduction of Fe 2ϩ . The reduction products were characterized using X-ray diffraction, scanning electronic microscope with energy disperse spectroscopy and optical microscopy analysis, respectively. The main phases in reduced products were reduced iron, rutile, reduced rutiles, pseudobrookite and Ti 3 O 5 . The reduction reaction proceeded topochemically and the reduction kinetics was discussed. It was found that the rate controlling step was the diffusion of hydrogen gas in the reduced layer.

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“…In stage 1, though graphite and Bakelite pellet showed linearity differently, in both case, X and − ln(1 − X), the slopes are nearly linear which implies that the rate is not controlled by one single mechanism, but a mixed control of possibly, mass transfer and chemical kinetics. 21) However in Stage 2 I and II, the curve shows better linearity when plotted with − ln(1 − X), which indicate that the reaction mechanism is predominantly controlled chemically. 21) This is also in agreement with the XRD results (Fig.…”

Section: Resultsmentioning

confidence: 98%

“…21) However in Stage 2 I and II, the curve shows better linearity when plotted with − ln(1 − X), which indicate that the reaction mechanism is predominantly controlled chemically. 21) This is also in agreement with the XRD results (Fig. 6), where it was observed that formation of Fe 5 Si 3 , FeSi, SiC, CaSiO 3 phase occurred within this stage (120 to 900 seconds) through chemical reactions.…”

Section: Resultsmentioning

confidence: 98%