Kinetics of atmospheric leaching from a brazilian nickel laterite ore allied to redox potential control

Author(s): Santos, A. L. A.; Becheleni, E. M.A; Viana, P. R. M.; Papini, R. M.; Silvas, F. P. C.; Roch, S. D. F.
Summary: The kinetics of atmospheric sulfuric acid leaching from a Brazilian nickel laterite ore was assessed using distinct reducing agents and ore mineralogy. This transitional ore contains 1.63% Ni distributed as 1.27% in coarse size (− 500 + 150 μm), mainly as silicates (lizardite and chlorite — 28.6%), and 2.06% in the fines fraction (− 75 μm), mainly as iron oxy-hydroxides (goethite and hematite — 49%). The effects of temperature, acid concentration, reducing reagent type, and concentration were evaluated. The − 75 μm fraction limited the leaching efficiency and the use of reducing media with thiosulfate improved leaching and Ni-Fe selectivity. However, at constant Eh of 626–743 mV and a pH range between 0.2 and 1.1, no substantial rise in metals extraction, except for Co and Mn, has been observed. In order to determine the process control at 95 °C, two regions in the extraction curves were used in combination with the shrinking core model.
Journal: Mining, Metallurgy & Exploration
Year: 2020
Pages: p. 1-15
Year of publication: 2020
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Publisher and ISSN: Springer