Sustainable ironmaking from low-grade iron ores: A kinetic study on thermal decomposition and reduction of iron (II) oxalate
Abstract
Decarbonization solutions enabling the use of low-grade iron ores are essential for a sustainable steel industry, reducing dependence on scarce high-grade ores and environmental impact. Current processes mainly require high-grade ores, highlighting the need for efficient methods to process lower-quality feedstocks. This study explores a hydro-pyrometallurgical approach for sustainable production. Dihydrate ferrous oxalate, obtained via oxalic acid extraction of iron oxide, was analyzed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), with postmortem samples characterized by X-ray powder diffraction. Non-isothermal experiments were conducted from 25 to 800 °C at 2, 5, and 10 °C/min under inert (argon) and reducing (carbon monoxide and hydrogen) atmospheres. The curves show three main steps: dehydration, decomposition, and, under reducing conditions, reduction to metallic iron. In carbon monoxide, iron carbide formation and graphitic carbon deposition were also observed. DSC revealed endothermic peaks for dehydration and decomposition and in carbon monoxide, a strong exothermic peak, due to the reverse Boudouard reaction.Activation energies were calculated using the Kissinger method. Dehydration showed an activation energy of 62 kJ/mol in argon and carbon monoxide, and slightly lower in hydrogen (58 kJ/mol), likely due to faster diffusion. Decomposition appeared gas independent, with an activation energy of 90 kJ/mol. A mathematical model was developed to relate reaction conversion to time at a fixed heating rate. The model accurately fits the experimental data and remains valid even at higher heating rates, comparable to industrial conditions. This kinetic model supports simulation and scale-up of the iron oxalate reduction process.
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BibTeX
@article{trinca2026sustainable,
title = {{Sustainable ironmaking from low-grade iron ores: A kinetic study on thermal decomposition and reduction of iron (II) oxalate}},
author = {Antonio Trinca and Nicola Verdone and Özge Özgün and Yan Ma and Isnaldi Filho and Dierk Raabe and Giorgio Vilardi},
journal = {Journal of Environmental Chemical Engineering},
year = {2026},
month = sep,
doi = {10.1016/j.jece.2025.119573},
url = {https://hal.science/hal-05752320v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Sustainable ironmaking from low-grade iron ores: A kinetic study on thermal decomposition and reduction of iron (II) oxalate
AU - Antonio Trinca
AU - Nicola Verdone
AU - Özge Özgün
AU - Yan Ma
AU - Isnaldi Filho
AU - Dierk Raabe
AU - Giorgio Vilardi
PY - 2026
DA - 2026/09/16
JO - Journal of Environmental Chemical Engineering
DO - 10.1016/j.jece.2025.119573
UR - https://hal.science/hal-05752320v1
AB - Decarbonization solutions enabling the use of low-grade iron ores are essential for a sustainable steel industry, reducing dependence on scarce high-grade ores and environmental impact. Current processes mainly require high-grade ores, highlighting the need for efficient methods to process lower-quality feedstocks. This study explores a hydro-pyrometallurgical approach for sustainable production. Dihydrate ferrous oxalate, obtained via oxalic acid extraction of iron oxide, was analyzed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC), with postmortem samples characterized by X-ray powder diffraction. Non-isothermal experiments were conducted from 25 to 800 °C at 2, 5, and 10 °C/min under inert (argon) and reducing (carbon monoxide and hydrogen) atmospheres. The curves show three main steps: dehydration, decomposition, and, under reducing conditions, reduction to metallic iron. In carbon monoxide, iron carbide formation and graphitic carbon deposition were also observed. DSC revealed endothermic peaks for dehydration and decomposition and in carbon monoxide, a strong exothermic peak, due to the reverse Boudouard reaction.Activation energies were calculated using the Kissinger method. Dehydration showed an activation energy of 62 kJ/mol in argon and carbon monoxide, and slightly lower in hydrogen (58 kJ/mol), likely due to faster diffusion. Decomposition appeared gas independent, with an activation energy of 90 kJ/mol. A mathematical model was developed to relate reaction conversion to time at a fixed heating rate. The model accurately fits the experimental data and remains valid even at higher heating rates, comparable to industrial conditions. This kinetic model supports simulation and scale-up of the iron oxalate reduction process.
SN - 2213-3437
SN - 2213-2929
ER -