Kinetic Study of Manganese Precipitation of Nickel Laterite Leach Based-solution by Ozone Oxidation

Abstract

ABSTRACT The increase in nickel and cobalt consumption encourages the exploration of different resources. Limonite ore exploration is carried out through the hydrometallurgical route. After nickel and cobalt separation, the remaining solution contains manganese to be recovered. The present study aimed at the kinetic modeling of manganese precipitation by ozonation. The experiments were carried out in a 250 mL reactor containing an 8-metals sulfated synthetic solution fed by an ozone-oxygen mixture with a bubble diffusor at 21.6–26.0 mg.L−1.min−1 to a total of 2186 mg.L−1 over 90 min. The effects of oxygen flow rate (0.8–10 L.L−1.min−1) and pH (0.5–1.5) varying the ozone dosages and time were studied. Kinetic modeling was performed using linear, Higbie, and pseudo-homogeneous orders. Results showed that the best oxygen flow rate for MnO2 was 2.0 L.L−1.min−1 achieving 97% of efficiency after dosing 24.3 mg.L−1.min−1 O3 or 2186 mg.L−1 (ozone applied) for 90 min at pH 1.5 with a power consumption of 80 W.L−1. The reaction was more selective at pH 0.5 in which the highest manganese precipitation of 55.4% and lower amount of contaminants in the solid phase were obtained. The kinetic model study has demonstrated that manganese precipitation using ozone fitted better on the pseudo-homogeneous model, suggesting that the process is controlled by mass transfer, where the calculated constant rates were 0.035, 0.033, and 0.042 min−1 for the experiments carried out at pH 0.5, 1.0 and 1.5, respectively.