Effect of a thermal pretreatment on dissolution kinetics of a limonitic lateriteore in chloride media

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The effect of a thermal pretreatment on the kinetic parameters and rate-controlling step for nickel leachingdissolution in hydrochloric acid‑sodium chloride solutions from a low–grade Colombian nickel laterite (1.15%Ni, 0.12% Co and 41.1% Fe), was evaluated. The mineralogical analysis showed that nickel is associated withiron in the form of hematite (Fe2O3) and goethite (FeOOH) within the calcined and uncalcined ore, respectively.The hydrochloric acid and total chloride ions concentrations, as well as the leaching temperature, were shown tohave a direct effect on nickel extraction. The experiments showed that ~92% of nickel can be dissolved afteronly 25 min in a 3 M HCl and 2 M NaCl solution when the leaching temperature was increased to 60 °C, after thesample had been previously calcined at 430 °C for 1 h. Nickel dissolution can be described by the chemicalreaction-controlled shrinking particle model for both the calcined and uncalcined sample with apparent acti-vation energies of 98 kJ/mol and 103 kJ/mol, respectively. This result suggests that a thermal pretreatmentstage does not affect the nickel reaction mechanism, although it may liberate the nickel within the lateritestructure.
Nickel, Colombian laterites, Hydrochloric acid leaching, Atmospheric leaching, Dissolution kinetics