Recovery of Iron from Nickel Production Waste By Electrolysis in Alkaline Aqueous Solution

Abstract

The global iron and steel industry is responsible for a noticeable part of energy consumption and anthropogenic CO2 emissions in the world. Different low-emission pathways have been taken by steel making companies around the world to replace the current iron and steel production. Among these evolving processes, low-temperature electrolysis of iron oxide, called SIDERWIN process, has shown promising results. Solid particles of iron oxide (Fe2O3) are reduced at the cathode in a strong NaOH solution at ~100 oC. This process has the flexibility to use different iron-containing raw materials as well as pure iron oxide. In the current study a waste product from nickel production (Glencore Nikkelverk, Kristiansand, Norway) was used as raw material. This waste material is in the form of sludge and contains up to 50 wt% FeOOH (akageneite). Cyclic voltammetry was performed to study the electrochemical properties of this material. Then, galvanostatic electrolysis was carried out and the product was analysed by SEM-EDS and X-ray diffraction. Pure iron was successfully deposited on the cathode. The faradaic efficiency was not very high in these initial trials. However, earlier studies using other raw materials (pure iron oxide and bauxite residue) have proved that optimisation of the electrolysis parameters can lead to significant increase in the efficiency.