Alternative Resources for Producing Nickel Matte - Laterite Ores and Polymetallic Nodules

Polymetallic nodules and nickel laterite ores are composed of various valuable metals and have similar nickel concentration, which makes them ideal alternatives for industries seeking to meet the increasing demand for nickel resources. The extraction process of polymetallic nodules can utilize the well-established nickel laterite treatment process without the need for developing new processes and thus, save capital costs. Herein, to efficiently extract nickel from these resources, high-temperature carbothermic reduction and sulfurization were investigated by optimizing the slag and matte systems. FactSage, a thermodynamic software was used to predict the slag system’s liquidus temperature and the formation of nickel matte. It was found that nickel matte formation was not dependent on CaSO4 addition whereas the nickel concentration in matte decreased with an increasing amount of the sulfiding agent FeS. Furthermore, the addition of a reductant significantly affected the concentration of nickel in the matte. A nickel concentration of ≥30 wt% and iron concentration of ≤40 wt% in matte were achieved by adding 0.5 wt% and 3 wt% carbon to nickel laterite ores and polymetallic nodules, respectively. Furthermore, replacing the sulfiding agent FeS with CaSO4 during the smelting of polymetallic nodules decreased the iron concentration in matte ≤15 wt% and increased the nickel concentration ≥50 wt%. Thus, this study confirmed the possibility of matte formation with high nickel concentration and low iron content by utilizing alternative nickel resources at 1350–1450°C.