Laterite Nickel Hydrometallurgical Residues Characterization and Potential Utilization of Valuable Elements

Approximately 80% of the hydrometallurgical process of low-grade laterite nickel ore is converted into residue. The handling of residues from processing is a significant challenge in this process According to the characterization test, each type of extraction process produces a different type of residue. The characteristics of the compound in the extraction process using High Pressure Acid Leaching (HPAL) and Sulfation-Roasting-Leaching (SRL) methods are similar to the dominance of Hematite (Fe2O3) and Fe content > 40%. Atmospheric leaching (AL) residues are dominated by compounds in the form of the mineral Fayalite with a high Si content (Si > 50%). Furthermore, Jarosite is a residue of the precipitation process of Fe impurities dissolved in Pregnant Leach Solution (PLS). Depending on the properties of the elements and compounds, each type of residue has divergent utilization potential. With a variety of recycle methods, SRL, HPAL, and jarosite waste can be converted into hematite as a raw material for the iron-steel industry. Roasting or alkaline leaching procedures can reduce the sulfur concentration in the residue to less than 1%. Furthermore, sponge iron (Fe metal) can be extracted using the direct reduction method from SRL and HPAL residue. The AL residue can be processed into the intermediate product sodium silicate. Sodium silicate can be utilized as a chemical absorbent, geopolymer, and adhesive product with the addition of additives and certain production process.