Zinc ferrite (ZnFe2O4) formation presents a challenge in Steelmaking Off-Gas Cleaning Systems hindering efficient Zn recovery. The kinetics of ZnFe2O4 formation on iron oxide particles through gas–solid reactions were measured in a Drop-Tube Reactor under the industrial operating conditions of an electric arc furnace: temperature of 950 °C to 1200 °C, particle residence time of 4 to 7 seconds, Zn partial pressure of 5 × 10−4 to 1 × 10−2 atm, CO2 partial pressure of 0.1 to 0.35 atm, and CO partial pressure of 2 × 10−4 to 7 × 10−2 atm. The nucleation and growth rate equation, with an Avrami parameter of 0.5, half-order dependence with respect to Zn, CO2, and CO partial pressures for Fe2O3, and 3/4, 1, and 1-order dependence with respect to Zn, CO2, and CO partial pressures for Fe3O4, respectively, well describes the ZnFe2O4 formation kinetics on Fe2O3 and Fe3O4. The following rate equations were developed, where the activation energy using Fe2O3 and Fe3O4 was 89 and 65 kJ mol−1, respectively:<InlineEquation ID="IEq1"> <EquationSource Format="TEX">$\frac{\text{d}}{X}_{\rm H}{\text{d}}t=\left[939\times {e}^{\frac{-89000}{RT}}\times \left[{\left({p}_{\rm Zn}\times {p}_{{\rm CO}_{2}}\right)}^{0.5}-{\left(\frac{{p}_{\rm CO}}{{K}_{\rm H}}\right)}^{0.5}\right]\right]\times \left[0.5\left(1-{X}_{\rm H}\right)\left[-\text{Ln}{\left(1-{X}_{\rm H}\right)]}^{-1}\right]\right]$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mfrac> <mtext>d</mtext> <mi>X</mi> </mfrac> <mi mathvariant="normal">H</mi> </msub> <mtext>d</mtext> <mi>t</mi> <mo>=</mo> <mfenced close="]" open="["> <mn>939</mn> <mo>×</mo> <msup> <mrow> <mi>e</mi> </mrow> <mfrac> <mrow> <mo>-</mo> <mn>89000</mn> </mrow> <mrow> <mi mathvariant="italic">RT</mi> </mrow> </mfrac> </msup> <mo>×</mo> <mfenced close="]" open="["> <msup> <mrow> <mfenced close=")" open="("> <msub> <mi>p</mi> <mi mathvariant="normal">Zn</mi> </msub> <mo>×</mo> <msub> <mi>p</mi> <msub> <mi mathvariant="normal">CO</mi> <mn>2</mn> </msub> </msub> </mfenced> </mrow> <mrow> <mn>0.5</mn> </mrow> </msup> <mo>-</mo> <msup> <mrow> <mfenced close=")" open="("> <mfrac> <msub> <mi>p</mi> <mi mathvariant="normal">CO</mi> </msub> <msub> <mi>K</mi> <mi mathvariant="normal">H</mi> </msub> </mfrac> </mfenced> </mrow> <mrow> <mn>0.5</mn> </mrow> </msup> </mfenced> </mfenced> <mo>×</mo> <mfenced close="]" open="["> <mn>0.5</mn> <mfenced close=")" open="("> <mn>1</mn> <mo>-</mo> <msub> <mi>X</mi> <mi mathvariant="normal">H</mi> </msub> </mfenced> <mfenced close="]" open="["> <mo>-</mo> <mtext>Ln</mtext> <msup> <mrow> <mfenced close=")" open="("> <mn>1</mn> <mo>-</mo> <msub> <mi>X</mi> <mi mathvariant="normal">H</mi> </msub> </mfenced> <mrow> <mo stretchy="false">]</mo> </mrow> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> </mfenced> </mfenced> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq2"> <EquationSource Format="TEX">$\frac{\text{d}}{X}_{\rm M}{\text{d}}t=\left[321\times {e}^{\frac{-65000}{RT}}\times \left[{\left({\left({p}_{\rm Zn}\right)}^{1.5}\times {\left({p}_{\text{CO}_{2}}\right)}^{2}\right)}^{0.5}-{\left(\frac{{\left({p}_{\rm CO}\right)}^{2}}{{K}_{\rm M}}\right)}^{0.5}\right]\right]\times \left[0.5\left(1-{X}_{\rm M}\right)\left[-\text{Ln}{\left(1-{X}_{\rm M}\right)]}^{-1}\right]\right]$</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mfrac> <mtext>d</mtext> <mi>X</mi> </mfrac> <mi mathvariant="normal">M</mi> </msub> <mtext>d</mtext> <mi>t</mi> <mo>=</mo> <mfenced close="]" open="["> <mn>321</mn> <mo>×</mo> <msup> <mrow> <mi>e</mi> </mrow> <mfrac> <mrow> <mo>-</mo> <mn>65000</mn> </mrow> <mrow> <mi mathvariant="italic">RT</mi> </mrow> </mfrac> </msup> <mo>×</mo> <mfenced close="]" open="["> <msup> <mrow> <mfenced close=")" open="("> <msup> <mrow> <mfenced close=")" open="("> <msub> <mi>p</mi> <mi mathvariant="normal">Zn</mi> </msub> </mfenced> </mrow> <mrow> <mn>1.5</mn> </mrow> </msup> <mo>×</mo> <msup> <mrow> <mfenced close=")" open="("> <msub> <mi>p</mi> <msub> <mtext>CO</mtext> <mn>2</mn> </msub> </msub> </mfenced> </mrow> <mn>2</mn> </msup> </mfenced> </mrow> <mrow> <mn>0.5</mn> </mrow> </msup> <mo>-</mo> <msup> <mrow> <mfenced close=")" open="("> <mfrac> <msup> <mrow> <mfenced close=")" open="("> <msub> <mi>p</mi> <mi mathvariant="normal">CO</mi> </msub> </mfenced> </mrow> <mn>2</mn> </msup> <msub> <mi>K</mi> <mi mathvariant="normal">M</mi> </msub> </mfrac> </mfenced> </mrow> <mrow> <mn>0.5</mn> </mrow> </msup> </mfenced> </mfenced> <mo>×</mo> <mfenced close="]" open="["> <mn>0.5</mn> <mfenced close=")" open="("> <mn>1</mn> <mo>-</mo> <msub> <mi>X</mi> <mi mathvariant="normal">M</mi> </msub> </mfenced> <mfenced close="]" open="["> <mo>-</mo> <mtext>Ln</mtext> <msup> <mrow> <mfenced close=")" open="("> <mn>1</mn> <mo>-</mo> <msub> <mi>X</mi> <mi mathvariant="normal">M</mi> </msub> </mfenced> <mrow> <mo stretchy="false">]</mo> </mrow> </mrow> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> </mfenced> </mfenced> </mrow> </math></EquationSource> </InlineEquation>.Under the studied conditions, Fe2O3 conversion to ZnFe2O4 is higher than that with Fe3O4. Maximizing Zn recovery while minimizing ZnFe2O4 formation becomes possible through In-Process Separation by combining this rate equation with continuous in situ measurements.

Mechanism and Kinetics of Zinc Ferrite Formation in the EAF Off-Gas Cleaning System

期刊论文
发表日期：

2026年4月6日

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John Frank Otero Olmos,
Hong Yong Sohn,
Naiyang Ma

摘要

Zinc ferrite (ZnFe₂O₄) formation presents a challenge in Steelmaking Off-Gas Cleaning Systems hindering efficient Zn recovery. The kinetics of ZnFe₂O₄ formation on iron oxide particles through gas–solid reactions were measured in a Drop-Tube Reactor under the industrial operating conditions of an electric arc furnace: temperature of 950 °C to 1200 °C, particle residence time of 4 to 7 seconds, Zn partial pressure of 5 × 10⁻⁴ to 1 × 10⁻² atm, CO₂ partial pressure of 0.1 to 0.35 atm, and CO partial pressure of 2 × 10⁻⁴ to 7 × 10⁻² atm. The nucleation and growth rate equation, with an Avrami parameter of 0.5, half-order dependence with respect to Zn, CO₂, and CO partial pressures for Fe₂O₃, and 3/4, 1, and 1-order dependence with respect to Zn, CO₂, and CO partial pressures for Fe₃O₄, respectively, well describes the ZnFe₂O₄ formation kinetics on Fe₂O₃ and Fe₃O₄. The following rate equations were developed, where the activation energy using Fe₂O₃ and Fe₃O₄ was 89 and 65 kJ mol⁻¹, respectively:

$\frac{\text{d}}{X}_{\rm H}{\text{d}}t=\left[939\times {e}^{\frac{-89000}{RT}}\times \left[{\left({p}_{\rm Zn}\times {p}_{{\rm CO}_{2}}\right)}^{0.5}-{\left(\frac{{p}_{\rm CO}}{{K}_{\rm H}}\right)}^{0.5}\right]\right]\times \left[0.5\left(1-{X}_{\rm H}\right)\left[-\text{Ln}{\left(1-{X}_{\rm H}\right)]}^{-1}\right]\right]$ ${\frac{d}{X}}_{H} d t = [939 \times e^{\frac{- 89000}{RT}} \times [{(p_{Zn} \times p_{{CO}_{2}})}^{0.5} - {(\frac{p_{CO}}{K_{H}})}^{0.5}]] \times [0.5, (1 - X_{H}), [- Ln {(1 - X_{H})]}^{- 1}]]$ , $\frac{\text{d}}{X}_{\rm M}{\text{d}}t=\left[321\times {e}^{\frac{-65000}{RT}}\times \left[{\left({\left({p}_{\rm Zn}\right)}^{1.5}\times {\left({p}_{\text{CO}_{2}}\right)}^{2}\right)}^{0.5}-{\left(\frac{{\left({p}_{\rm CO}\right)}^{2}}{{K}_{\rm M}}\right)}^{0.5}\right]\right]\times \left[0.5\left(1-{X}_{\rm M}\right)\left[-\text{Ln}{\left(1-{X}_{\rm M}\right)]}^{-1}\right]\right]$ ${\frac{d}{X}}_{M} d t = [321 \times e^{\frac{- 65000}{RT}} \times [{({(p_{Zn})}^{1.5} \times {(p_{{CO}_{2}})}^{2})}^{0.5} - {(\frac{{(p_{CO})}^{2}}{K_{M}})}^{0.5}]] \times [0.5, (1 - X_{M}), [- Ln {(1 - X_{M})]}^{- 1}]]$ .

Under the studied conditions, Fe₂O₃ conversion to ZnFe₂O₄ is higher than that with Fe₃O₄. Maximizing Zn recovery while minimizing ZnFe₂O₄ formation becomes possible through In-Process Separation by combining this rate equation with continuous in situ measurements.