Effect of FE(II) concentration on bioleaching of zinc from sphalerite using leptospirillum ferriphilum: Kinetic aspects

Abstract

The objective of this study was to isolate an acidophilic iron-oxidizing bacterium, Leptospirillum ferriphilum, and explore the impacts of initial Fe(II) concentration on the bioleaching kinetics of zinc retrieval from sphalerite concentrate. L. ferriphilum strain was successfully isolated from Chitradurga mine, Karnataka, India, and molecular techniques for DNA sequencing were applied. The obtained nucleotide sequence was deposited to GenBank and accession number KF743135 was granted. The effect of Fe(II) on the iron-based bioleaching kinetics of zinc leaching using the L. ferriphilum isolate was ascertained under the following experimental conditions: inoculum size, 10% (v/v); bioleaching period, 20 days; system temperature, 301±2 K; initial pH, 3; pulp density 5% (w/v); and Fe(II) concentration in the medium, 1–9 g/L. The results demonstrated that efficiency of bioleaching was highly influenced by concentration of Fe(II) and maximized yield of 87.85% zinc was obtained at 7 g/L. The kinetic study specify that the rate constant estimations of zinc biosolubilization were moderately high at 7 g/L Fe(II), and the kinetic analysis using shrinking core model showed that the leaching rate is constrained by ash layer diffusion step.