Acid leaching and rheological behaviour of siliceous goethite Ni laterite ore: effect of solid loading and temperature
Date
2013
Authors
Nosrati, A.
MacCarthy, J.
Addai Mensah, J.
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Conference paper
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2013 Chemeca proceedings: Challenging Tomorrow, 2013, pp.404-412
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2013 Chemeca (29 Sep 2013 - 2 Oct 2013 : Brisbane, Australia)
Abstract
In recent decades, there has been a gradual shift from pyrometallurgical to hydrometallurgical methods to extract nickel (Ni) and cobalt (Co) from ore deposits. This is due to depletion of high grade sulphide ores and increasing need for processing of complex, low grade lateritic ores. Agitated tank leaching is a favourable hydrometallurgical processing route, compared with high pressure acid leaching, due to its lesser energy and capital cost requirement. In this study, acid leaching and rheological behaviour of siliceous goethitic Ni laterite ore are investigated. Specifically, the effect of solid loading (30 vs. 45 wt.%) and temperature (70 vs. 90°C) on acid consumption capacity, Ni/Co recovery and pulp shear viscosity/yield stress was studied in isothermal, batch, 4h leaching tests on -200 μm feed particles at pH 1. Rapid and incongruent leaching of Na, Ca and Si from acid consuming gangue minerals such as serpentine, kaolinite and nontronite, accompanied by slower but steady release of Ni, Co, Fe, Mg and Al was observed. Higher temperature and lower pulp solid loading, both led to a 40 - 80% increase in Ni and/or Co recovery and higher acid consumption capacity but a weaker pulp rheology. At 70°C and 45 wt.% solid loading, Ni/Co recovery was the lowest (~15% ), and the pulp shear viscosity and yield stress systematically increased with time, leading to gelation. The implications of the findings are discussed in terms of improving lateritic ores' atmospheric acid leaching behaviour in agitated tanks.
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Copyright 2013 Engineers Australia