Kinetics of reduction step of wustite to iron in gaseous reduction of quaternary calcium ferrite

Takayuki Maeda, Yoichi Ono

Research output: Contribution to journalArticle

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Abstract

As a fundamental study for clarifying the reduction phenomena of sintered ore in a blast furnace, quaternary calcium ferrite was synthesized from chemical reagents of Fe2O3, CaCO3, SiO2, and Al2O3 and the kinetic behavior at the final stage of reduction of the quaternary calcium ferrite with CO and H2 gas was studied. The results obtained are summarized as follows: (1) Reduction rate increased with an increase in temperature both in CO and H2 reductions. The increase of reduction rate with temperature was not very large above 900°C but it was remarkably large between 800°C and 900°C. (2) Reduction at 900°C and above proceeded topochemically both in macro- and microstructures. At 800°C, the reduction did not proceed topochemically but rather homogeneously. (3) Reduction data at 900°C and above were analyzed based on the unreacted-core model. Reduction curves calculated by using the rate parameters obtained by the analysis agreed with the observed data very well. Temperature dependencies of the chemical reaction rate constant ke and the effective diffusivity in the product layer De were given by following equations: keCO = exp (13.28-164.9 × 103/RT) (m/s) (1173 approximately 1273 K) DeCO = exp (-7.16-32.07 × 103/RT) (m2/s) (1173-1273 K) keH(2) = exp (3.62-55.83 × 103/RT) (m/s) (1173 approximately 1273 K) DeH(2) = exp (-3.61-53.91 × 103/RT) (m2/s) (1173 approximately 1273 K).

Original languageEnglish
Pages (from-to)1569-1576
Number of pages8
JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
Volume77
Issue number10
DOIs
Publication statusPublished - Jan 1 1991

Fingerprint

Ferrite
calcium
ferrites
Calcium
Iron
iron
Kinetics
kinetics
Carbon Monoxide
ferrous oxide
data reduction
blasts
Blast furnaces
Temperature
Ores
Reaction rates
diffusivity
furnaces
temperature
reagents

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Metals and Alloys
  • Materials Chemistry

Cite this

Kinetics of reduction step of wustite to iron in gaseous reduction of quaternary calcium ferrite. / Maeda, Takayuki; Ono, Yoichi.

In: Tetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan, Vol. 77, No. 10, 01.01.1991, p. 1569-1576.

Research output: Contribution to journalArticle

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abstract = "As a fundamental study for clarifying the reduction phenomena of sintered ore in a blast furnace, quaternary calcium ferrite was synthesized from chemical reagents of Fe2O3, CaCO3, SiO2, and Al2O3 and the kinetic behavior at the final stage of reduction of the quaternary calcium ferrite with CO and H2 gas was studied. The results obtained are summarized as follows: (1) Reduction rate increased with an increase in temperature both in CO and H2 reductions. The increase of reduction rate with temperature was not very large above 900°C but it was remarkably large between 800°C and 900°C. (2) Reduction at 900°C and above proceeded topochemically both in macro- and microstructures. At 800°C, the reduction did not proceed topochemically but rather homogeneously. (3) Reduction data at 900°C and above were analyzed based on the unreacted-core model. Reduction curves calculated by using the rate parameters obtained by the analysis agreed with the observed data very well. Temperature dependencies of the chemical reaction rate constant ke and the effective diffusivity in the product layer De were given by following equations: keCO = exp (13.28-164.9 × 103/RT) (m/s) (1173 approximately 1273 K) DeCO = exp (-7.16-32.07 × 103/RT) (m2/s) (1173-1273 K) keH(2) = exp (3.62-55.83 × 103/RT) (m/s) (1173 approximately 1273 K) DeH(2) = exp (-3.61-53.91 × 103/RT) (m2/s) (1173 approximately 1273 K).",
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N2 - As a fundamental study for clarifying the reduction phenomena of sintered ore in a blast furnace, quaternary calcium ferrite was synthesized from chemical reagents of Fe2O3, CaCO3, SiO2, and Al2O3 and the kinetic behavior at the final stage of reduction of the quaternary calcium ferrite with CO and H2 gas was studied. The results obtained are summarized as follows: (1) Reduction rate increased with an increase in temperature both in CO and H2 reductions. The increase of reduction rate with temperature was not very large above 900°C but it was remarkably large between 800°C and 900°C. (2) Reduction at 900°C and above proceeded topochemically both in macro- and microstructures. At 800°C, the reduction did not proceed topochemically but rather homogeneously. (3) Reduction data at 900°C and above were analyzed based on the unreacted-core model. Reduction curves calculated by using the rate parameters obtained by the analysis agreed with the observed data very well. Temperature dependencies of the chemical reaction rate constant ke and the effective diffusivity in the product layer De were given by following equations: keCO = exp (13.28-164.9 × 103/RT) (m/s) (1173 approximately 1273 K) DeCO = exp (-7.16-32.07 × 103/RT) (m2/s) (1173-1273 K) keH(2) = exp (3.62-55.83 × 103/RT) (m/s) (1173 approximately 1273 K) DeH(2) = exp (-3.61-53.91 × 103/RT) (m2/s) (1173 approximately 1273 K).

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