Direct Electrodeposition of High-Purity Iron from Fe₂O₃ in Molten Calcium Chloride

Abstract

The low-cost production of high-purity metallic iron is of great practical importance. Herein, we report the direct production of high-purity metallic iron (99.92%) via a one-step electrochemical strategy in molten CaCl₂–CaO–Fe₂O₃ system at 850°C. The involved CaO-assisted dissolution of Fe₂O₃ and electrodeposition mechanism were systematically studied, and the obtained iron products were characterized using scanning electron microscopy, inductively-coupled high-frequency plasma emission spectrometry, and glow discharge mass spectrometry. The results show that the crystalline iron products with tunable morphologies can be obtained in a controlled manner. The electrolysis parameters (voltage, current density, electrodeposition time and substrate material) have significant effects on the electrodeposition process and the characteristics of iron products. In particular, high-purity dense iron film can be directly electrodeposited at 15 mA∙cm⁻², and its thickness increases considerably with increasing electrodeposition time. Furthermore, the as-deposited iron product can also be processed into bulk iron materials with high-purity of 99.995 wt.% by plasma melting for the potential applications. In general, this one-step electrodeposition process provides an acid-/alkaline-free strategy for the facile production of high-purity iron materials direct from Fe₂O₃.