Electrochemical studies on interplay of mineralogical variation and particle size on bioleaching low grade complex sulphide ores

• Published in: Transactions of Nonferrous Metals Society of China Vol. 19; no. 5; pp. 1312 - 1325
• Main Authors: OLUBAMBI, P.A., POTGIETER, J.H., NDLOVU, S., BORODE, J.O.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-10-2009; Department of Chemical and Metallurgical Engineering, Tshwane University of Technology, Pretoria, South Africa%Chemistry and Materials Division, School of Biology, Chemistry and Health Sciences,Manchester Metropolitan University, UK%School of Chemical and Metallurgical Engineering, University of the Witwatersrand,Johannesburg, South Africa%Department of Metallurgical and Materials Engineering, Federal University of Technology, Akure, Nigeria
• Subjects: Acidithiobacillus ferrooxidans; Acidithiobacillus thiooxidans; bioleaching; electrochemical study; Leptospirillum ferrooxidans; ore mineralogy; particle size; sulphide ore; sulphide ore; particle size; ore mineralogy; bioleaching; electrochemical study
• ISSN: 1003-6326
• DOI: 10.1016/S1003-6326(08)60443-4

The interplay of mineralogical variation and mineral phase distribution within varying particle sizes on the dissolution behaviour of a low grade complex sulphide ore was investigated through bioleaching experiments and electrochemical technique. Investigations were carried out utilizing mineralogical data on the variations in mineral and phase distribution within particle sizes of <53 μm, 53–75 μm, 75–106 μm and 106–150 μm in mixed mesophilic cultures of
Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and
Leptospirillum ferrooxidans. Electrochemical behaviour was studied using particulate electrodes from the four varying particle sizes and from massive electrodes prepared from the two major sulphide mineral rich phases (sphalerite-rich and galena-rich) and a complex mineralogical phase of the bulk ore. Bioleaching studies reveal the highest recoveries at a particle size of 75 μm, while electrochemical investigations reveal the highest dissolution at particle size of 106 μm. Electrochemical results show that sphalerite rich phase has the highest dissolution rate while galena-rich complex phase has the least. SEM studies confirm the highest bacterial attack at the sphalerite-rich phase. The discrepancies between the dissolutions within particle sizes obtained from bioleaching experiments and electrochemical studies are consistent with and attributed both to the physical and mineralogical influences. Electrochemical behaviour is influenced and controlled by galvanic interaction resulting from mineralogical variation, while bioleaching behaviour is influenced by mineralogical variation as well as physical effect of particle size.