The Effect of Additives on Extraction of Ni, Fe and Co from Nickel Laterite Ores

As nickel sulfide deposits are exhausted, it becomes necessary to mine and process low-grade laterite ores to satisfy the need for nickel production. To achieve an efficient extraction of Ni, Fe and Co, additives such as chlorides, sulfur and sulfates, alkali oxides, fluorides, sodium carbonate and sodium hydroxide are introduced into the extraction process, and are applied in the reduction roasting-magnetic separation and chloridizing/sulfating/alkali roasting followed by a leaching process. In this paper, previously reported studies on the extraction of Ni, Fe and Co from nickel laterite ores have been reviewed with an emphasis on the additives' effect and reaction mechanisms. Although these additives significantly improve the enrichment effect, there is a need for further research on reaction mechanisms, particularly with regard to hydrolysis of chlorides that generate HCl. The development of efficient additives that are environmentally friendly with low corrosivity and low cost should also be investigated.