Iodination volatilization roasting of ferronickel alloys for selectively volatilizing iron and simultaneously obtaining nickel containing powder

Abstract

The rotary kiln-electric furnace process represents one of the most efficient industrial pathways for the extraction of nickel from laterite nickel ores. However, the product of this process, a ferronickel alloy, which contains approximately 55–85% iron and 15–45% nickel, necessitates the selective removal of iron before it can be utilized as a nickel source for power battery production. In this paper, an iodination volatilization roasting method was developed and used to separate iron from the ferronickel alloy, and nickel powder was obtained. Thermodynamic analysis and density functional theory (DFT) calculations were applied to elucidate the underlying mechanism. Our findings indicate that, by controlling the reaction temperature, the iodination volatilization roasting process can efficiently volatilize iron and copper, leaving nickel in its metallic state. Specifically, iron and copper volatilization efficiencies reached 96.5% and 97.1%, respectively, while only 8.4% of the nickel was volatilized after 2 hours of roasting at 1000 °C. This mechanistic insight was further supported by experimental roasting data and subsequent characterization of the roasted slags. Moreover, the potential for iodine regeneration within the process was demonstrated through oxidation roasting experiments of FeI₂, confirming the recyclability of iodine in the system. This process provides a route for the high-efficiency separation of Fe from the ferronickel alloy, and Ni in the alloy is obtained in the form of nickel powder.