Continuous Bioleaching of a Cobaltiferous Pyrite in Stirred Reactors: Population Dynamics and EPS Production vs. Bioleaching Performances


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In the frame of a European project (BioMinE - FP6), a continuous bioleaching operation was carried out in a laboratory-scale unit using a cobaltiferous pyrite. The objective of the work was to use this system to investigate mechanisms of microbial activity and mineral oxidation in continuous stirred bioreactors (1x50L - 3x20L). A combination of scientific and technical approaches (molecular ecology, biochemistry and microscopy) was used and various key operating parameters were tested (temperature, nitrogen source, CO2 availability, designed consortia). An increase of temperature of 10°C (35°C to 45°C) had no major influence on the bioleaching efficiency. When the ammonium source was limiting, there was a negative influence on both bacterial growth and bioleaching efficiency. This result was related to a combination of factors such as less bacterial attachment to the pyrite surface and less precipitate formation. CO2 limitation had a very significant negative effect on the bacterial productivity and consequently on the bioleaching efficiency. Nevertheless, the population composition remained unchanged. An important decrease of EPS (sugar) production was also observed. The bacterial strains, that dominate the culture, originated from the deposit in Uganda. It seems that their bioleaching ability was improved over the time when cultured in continuous mode. The culture composition was very stable. The iron-oxidizer L. ferriphilum was the dominant organism in standard (not limiting) conditions, and was always very well represented during the first 3-4 days of residence time. Sulfobacillus sp. BRGM2 also played an important role in the process. This study gives new insights for the application of this technology, and more specifically on the influence of key operating parameters on bioleaching performances, population dynamics and attachment of bacteria to the solid surfaces.



Advanced Materials Research (Volumes 20-21)

Edited by:

Axel Schippers, Wolfgang Sand, Franz Glombitza and Sabine Willscher




P. D'Hugues et al., "Continuous Bioleaching of a Cobaltiferous Pyrite in Stirred Reactors: Population Dynamics and EPS Production vs. Bioleaching Performances", Advanced Materials Research, Vols. 20-21, pp. 62-65, 2007

Online since:

July 2007




[1] Morin, D. and d'Hugues, P. in: Biomining, Rawlings, D.E. and Johnson, D. B. (eds. ), Chapter 2, Springer, Heidelberg (2007).

[2] Information on http: /biomine. brgm. fr/ Acknowledgement This work was carried out in the frame of BioMinE (European project contract NMP2-CT-2004 500-329). The authors acknowledge the financial support given to this project by the European Commission under the Sixth Framework Programme for Research and Development. This paper is published with the permission of BRGM as scientific contribution No. 4967.

[10] [20] [30] [40] [50] [60] [70] [80] [90] 100 0 2 4 6 8 Residence time (d) Cobalt Dissolution (%) Designed consortia standard.