The nickeliferous laterites obtained from Sukinda region, Orissa, India were characterized by using microscopic investigations, XRD, DTA/TG, SEM and IR techniques. The different peaks identified from their characteristic peaks were goethite, hematite, quartz and chromite. The high temperature XRD at 120°C and 220°C shows an insignificant change indicating that the structural change is almost prohibited at this temperature. DTA/TG and IR study of different laterite samples were discussed in detail. The fixation of nickel in various crystalline lattices were established using differential chemical extraction methods. A relationship has been established between bulk density and percentage Fe_2O_3 and NiO. The characterized samples were pugged with sulphuric acid in a silica crucible and roasted in laboratory scale. The crucible with charge was placed in a stainless steel reactor and roasted in a muffle furnace in three different modes. The roasted mass was cooled to room temperature and leached with water at 90-95°C for 30 minutes at a solid liquid ratio of 1:10. A mass balance was performed for each experiment, based on total nickel and iron present in the feed, the leach solution and residue. Various roasting parameters were studied and it is observed that the roasting temperature and time are the most vital factors for selective extraction of nickel with respect to iron. It is concluded that a temperature of 700°C, 25 wt% acid and 15 minutes time are found to be effective for the preferential extraction of around 85% nickel with 2.5% iron.
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