African Journal of

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12278

Full Length Research Paper

Bioleaching of metal ions from low grade sulphide ore: Process optimization by using orthogonal experimental array design

Sadia Ilyas1,2, Haq Nawaz Bhatti2*, Ijaz Ahmad Bhatti2, Munir Ahmad Sheikh2and Muhammad Afzal Ghauri3
  1Hubei Key Laboratory of Novel Reactor and Green Chemical Technology, Wuhan Institute of Technology, Wuhan, China. 2Department of Chemistry and Biochemistry, University of Agriculture, Faisalabad, Pakistan. 3 National Institute for Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan.
Email: [email protected]

  •  Accepted: 06 April 2010
  •  Published: 10 May 2010



The present work was aimed at studying the bioleachability of metal ions from low grade sulphide ore containing high amount of carbonaceous materials by selected moderately thermophilic strain of acidophilic chemolothotrophic bacteria,Sulfobacilllus thermosulfidooxidans. The bioleaching process was optimized by constructing L25 Taguchi orthogonal experimental array design and optimization of variable proportions of process parameters. Five factors were investigated and twenty five batch bioleaching tests were run under lower, medium and higher levels of these factors. The parameters considered for shake flask leaching experiments were initial pH (1.8, 2, 2.5, 3, 3.5), particle size, (50, 100, 120, 200, 270 μm), pulp density (1, 5, 10, 15, 25%), temperature (40, 45, 47, 52, 57oC) and agitation (100, 120, 180, 220, 280 rpm). Statistical analysis (ANOVA) was also employed to determine significant relationship between experimental conditions and yield levels. The experimental results for selective leaching showed that under engineered leaching conditions; pH 1.8, particle size 120 μm, pulp density 10%, temperature 47°C and agitation 180 rpm, the percent bioleachabilities of metals were Zn 72%, Co 68%, Cu 78%, Ni 81% and Fe 70% with an inoculum size of 1.0 ×10/mL.


Key words: Mineral economics, process optimization, bioleaching, sulphide ores, bacteria.