Mineralogical Characterization of Limonitic Laterite from Africa and Its Proposed Processing Route

Abstract

The mineralogical characterization and occurrence of target elements in limonitic laterite from Africa was comprehensively studied by X-ray diffraction (XRD), scanning electron microscopy energy spectrum (SEM–EDS), and optical microscope (OM) measurements. The results suggest that laterite ore has a complex internal structure. In the limonitic laterite, the contents of Ni, Co, and Fe are 1.14%, 0.16%, and 45.91%, respectively. The limonitic laterite mainly contains 72.2% iron oxide/oxyhydroxide, 9.37% silicate, 6.22% chlorite. Limonite, chlorite, and manganese oxide are the main nickel carrier with distribution rates of 60.98%, 22.65%, and 13.94%, respectively. Cobalt is hosted in manganese oxides and iron oxides, respectively. Additionally, Au, Pt, Pd, and Ag are also detected in the limonitic laterite. Gold, platinum, and silver are mainly found in their native metals. Palladium is mainly dispersed in the iron minerals. Furthermore, the route of rotary kiln-electric furnace (RKEF) was selected to this limonitic laterite; the results demonstrate that comprehensive recovery efficiency of Ni, Co, Fe is high with recovery rate of 98.72%, 98.38%, 54.89%, respectively. Notably, the majority of noble metals such as Au, Pt, Pd are enriched in crude ferronickel.