The study of mixed hydroxide precipitate (MHP) from local mineral resources in Indonesia

Indonesia has the largest nickel source in the world. It is estimated, there are about 21 million metric tons of nickel reserves in Indonesia. Laterite nickel ore is the most abundant nickel source especially in tropical regions. Mixed hydroxide precipitate (MHP) is intermediate product of this process. In this research, the MHP product from PT. Smelter Nickel Indonesia (PT.SNI) was investigated. The MHP quality content is important for further process of nickel refinery to become Nickel and Cobalt sulphate for battery industry. The MHP was characterized by an X-ray diffraction (XRD), a Scanning Electron Microscope (SEM), a Differential Thermal Analysis. The XRD shows that the untreated MHP was an amorphous-like material that corresponded to Jamborite type mineral, consisting of Ni-O-H. The microstructure consists some unregular shapes with various particle sizes of 1 to 20 µm, whereas some was agglomerated. The thermal data shows there are two endothermic peaks related to the dehydration of moisture and hydrated crystal, while the second was the dehydration of OH group. After the heat treatment of MHP at 850^oC, the X-ray diffraction pattern consisted of several phases identified as 82.6% Bunsenite (NiO), 12.4% Cobalt Dicobalt(III) Oxide (Co₃O₄) and 5% Aluminum Oxide−Alpha (Al₂O₃) according to Rietveld refinement analysis. The NiO was expected to be the highest content of MHP, followed by Co₃O₄.