The production of iron metal with low greenhouse gas emissions can be performed by electrolysis. However, the electrolytic reduction of iron ore is not a technique that has reached a high degree of knowledge and development. With the aim of getting insight into the electrochemical reaction mechanism, this work shows that the reduction of iron ore to metal at low temperature in alkaline electrolyte is possible and occurs in a solid-state macroscopic mode. Electrochemical reactions take place in the volume of the solid, progressing from its outer surface toward the core, leading to full conversion to metal. A magnetite intermediate phase has been identified and high current efficiency is measured. Such a reaction occurs at high reaction rates, which further stimulates the interest of producing iron metal by the sole use of electricity.
The electrodeposition of metal iron from iron dissolved species in alkaline media has been investigated. Dissolved ferric species in equilibrium with hematite
(α-Fe2normalO3)
have been electrochemically identified and their reduction to iron was demonstrated. The reduction efficiency was poor, however, because of the low concentration of dissolved matter
(2.6×10−3M)
. In order to determine more precisely the electrochemical features of the deposition reaction from iron ions, more concentrated solutions at
1.9×10−2M
have been obtained using an iron anode as the ion source. Voltammetric and chronoamperometric investigations using a rotating disk electrode revealed that such concentrated solutions contain ferric and ferrous species, with higher concentration of the trivalent form. Metal can be deposited with higher current efficiency in these concentrated solutions with less than
30%
of the current spent in hydrogen evolution.
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