Waste Valorization Process: Sulfur Removal and Hematite Recovery from High Pressure Acid Leach Residue for Steelmaking

Abstract

The current study put the emphasis on developing a novel and environmentally friendly waste valorization process to refine hematite from the residue of the high-pressure acid leaching (HPAL) of nickel laterite ore. The developed process consists of an alkaline leaching step utilizing sodium hydroxide to reduce the sulfur impurity content in the HPAL residue. This novel process is very efficient as it can be run at room temperature in a significantly short residence time (10 min). The refined HPAL residue has sulfur content below the accepted threshold by the steelmaking industry; hence, it can potentially be used as a raw material. The proposed waste valorization process has the double advantage of generating a commercially valuable product from otherwise a waste stream and simultaneously providing environmental benefits through reducing the amount of scrapped leach residue and costs associated with constructing and maintaining storage facilities.