Abstract
The Akanani Project is situated in the Central Sector of the Platreef on the northern limb of the Bushveld Complex. The platinum group elements (PGE) mineralisation is primarily restricted to the P1 and P2 geological units of the Platreef at Akanani. Mineralisation in the P1 Unit is erratic and occurs over a wide vertical interval. In contrast, the overlying P2 unit is more uniformly mineralised, with generally higher grades than P1.
Previously published studies of the Platreef focused mainly on an understanding of its geology and mineralogy, with published insights into its processing behaviour being comparatively rare. The present study therefore aims to investigate the geometallurgical nature of the P1 and P2 units of the Platreef at Akanani, with a focus on the influence of various ore properties (mineralogy, sulphide grain size, sulphide liberation) on the recovery of the PGE, as well as nickel (Ni), copper (Cu) and sulphur (S).
Various ore types were sampled. These include feldspathic pyroxenite and serpentinised pyroxenite occurring in P1 and P2 units. Orthopyroxene, clinopyroxene and plagioclase are the dominant primary silicate minerals, with serpentine the dominant secondary silicate. Base metal sulphides comprise dominant pyrrhotite, along with pentlandite and chalcopyrite. The size distributions of the sulphides are variable, with the finest encountered in the serpentinised pyroxenite, and the coarsest sulphides occurring in the feldspathic pyroxenite. Milling times required in order to reduce these ore types to 60% passing 75 μm, are variable, with the P2 feldspathic pyroxenite milling the fastest, and the P2 serpentinised pyroxenite the slowest. Levels of liberation upon milling are comparatively poor for the serpentinised pyroxenite, and significantly better in the case of the feldspathic pyroxenite. This is mirrored by the recovery of the PGE from the various ore types, with lower recoveries associated with the serpentinised ore types and better recoveries associated with the feldspathic pyroxenite.
M.Sc. (Geology)