Sustainable Iron-Making Using Oxalic Acid: The Concept, A Brief Review of Key Reactions, and An Experimental Demonstration of the Iron-Making Process

Abstract

Global iron and steel production continues to expand. The iron-making industry is, however, one of the main contributors to global warming due to its reliance on fossil fuel-based high temperature processes. Therefore, alternative green approaches to iron-making are highly desired. Herein, we propose a new concept of iron-making, which consists of a sequence of known reactions: the dissolution of iron from iron ore using oxalic acid to obtain a Fe­(III) oxalate aqueous solution, followed by the photochemical reduction of Fe­(III) oxalate to Fe­(II) oxalate as a solid precipitate, and the pyrolytic reduction of Fe­(II) oxalate to metallic iron. By harnessing the chemical characteristics of oxalic acid and iron oxalates, the method is expected to produce high-quality iron at low temperatures. Moreover, the recovery of carbon oxides, generated during iron-making, for the synthesis of oxalic acid enables the iron-making without having carbon in the stoichiometry. The present study explains the key chemical concepts of the process, experimentally demonstrates the iron-making, and discusses the challenges and barriers to industrial application. In the experiment, according to the proposed scheme, three different iron sources were successfully converted into metallic iron. The yield and quality (purity) of the iron product depended on the metallic composition of the feedstock. In the absence of impurity metals, near-complete recovery of pure iron was possible. Alkaline earth and transition metals were identified as impurities that affected process performance and product quality. The iron dissolution needed a relatively long reaction time to achieve sufficient conversion under the conditions employed in this study, rendering it a rate-determining step that influenced overall iron productivity.

High-Strength Formed Coke from Torrefied Biomass and Its Blend with Noncaking Coal

“…This work has demonstrated preparation of formed coke from noncaking coal and torrefied cedar over the entire range of mixing ratio with S t,C greater than conventional blast furnace coke of 5–6 MPa . Although not measured in this work, cokes from TC–coal mixtures as well as TC are expected to have higher reactivities with CO 2 than those from the coals alone, according to previous studies. − Such high reactivity is arisen primarily from inherent metallic species (alkali and alkaline earth metallic species; AAEMs and transition metals such as Fe). − Influence of the carbon structure of biomass-derived coke on the reactivity is, if any, much less important than the catalytic roles of metallic species. , The present cedar sample in fact retained K, Ca, and Fe with contents of 0.19, 0.29, and 0.06 wt %-dry, respectively …”

“…The world steel industries have been requested to deeply reduce CO 2 emission from steelmaking processes and to realize zero emission. , The reduction of CO 2 emission is contributed potentially by a variety of technologies, as reviewed by Quader et al and Hasanbeigi et al Some technologies rely on blast furnace (BF) and coke production processes with effective utilization of CO, H 2 , and CH 4 from BF and coke oven as reducing agents or fuels, CO 2 capture and storage, and replacement of coal by biomass as feedstock of coke or fuel. , Technologies such as smelting, direct iron ore reduction by H 2 , − electrolysis, and reduction by organic reducing agents are alternatives to BF technologies. Among the above-mentioned advanced and emerging technologies, BF coke production from biomass, in particular, from biomass/coal mixture at any mixing ratio, was the target of this work.…”

Dissolution of Iron Oxides Highly Loaded in Oxalic Acid Aqueous Solution for a Potential Application in Iron-Making

“…The irradiation of light, particularly within the tropospheric solar UV-visible region (290-570 nm), causes reduction of Fe(III) oxalate to water-insoluble Fe(II) oxalate. 22) The quantum efficiency of this photochemical reaction is close to unity. 26) Upon the light irradiation, the amount of dissolved iron, therefore, readily decreases.…”

“…A1. 22) Iron dissolved mainly as Fe(III) oxalate (Eq. ( 1) for Fe 2 O 3 ) is reduced to metallic iron in two steps; photochemical reduction and pyrolytic reduction.…”

Synthesis of Oxalate from CO₂ and Cesium Carbonate Supported Over Porous Carbon

“…Iron was extracted from iron ores as iron (III) oxalate, photochemically reduced to iron (II) oxalate, and then converted to metallic iron by pyrolytic reduction. 8,9) Because of the unique properties of oxalic acid and oxalates, the metallic iron was produced even at a low temperature of 500°C from low-grade iron ores, and it had high purity. However, the current market for oxalic acid is not large enough to support iron-making.…”