Bioleaching kinetics of chalcopyrite concentrate using leptospirillum ferriphilum: effect of silver ion

Venkatesa Prabhu S, Barathiraja P, Karthik R and Ragul V

Bioleaching is a proven eco-friendly biological method to extract metals from their ores. One of the important problems faced in bioleaching is the low leaching rate, which consumes high residence time. In this study, the catalytic effect of silver ion (Ag+) on bioleaching of copper and iron from chalcopyrite concentrate was investigated using isolated bacteria, Leptospirillum ferriphilum, for enhancing the leaching rate. The bioleaching data were collected for Cu and Fe extraction from chalcopyrite concentrates using different concentrations of silver ion (1−5 mg/L) with the following fixed parameters: initial pH, 1.5; pulp density, 1% (w/v); particle size, 200 µm; and agitation speed, 180 rpm. From the obtained results, it was found that the maximized leaching of Cu (87.73%) and Fe (74.73%) occurred while using 4 mg/L silver ion concentration. The kinetic study on bioleaching data indicated that the rate constants for Cu and Fe leaching were found to be maximum (0.078 and 0.054 d1, respectively) at Ag+ concentration 4mg/L. The leaching data were analyzed using shrinking core model for determining the rate-controlling step. It explicated that the diffusion through product layer forms on the mineral surface controls the rate of leaching.

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