Investigating the Microbial Metabolic Activity on Mineral Surfaces of Pyrite-Rich Waste Rocks in an Unsaturated Heap-Simulating Column System

Abstract:

Microbial association with and colonisation of mineral surfaces plays a key role in enhancing the extraction of metals from ores during heap bioleaching processes. On the other hand, if uncontrolled, the same association can also lead to the generation of acid rock drainage (ARD) effluents from mine waste. This study aims to measure microbial metabolic activity of a mixed mesophilic culture on the surfaces of pyrite-bearing waste rocks of different grades over time. The waste rocks are milled, size fractionated and coated onto glass beads, to provide a defined surface area. The metabolic activity on the mineral surface is measured with isothermal microcalorimetry (IMC) complemented with scanning electron microscopy (SEM) and analysis of solution chemistry to measure leach agents and metal release into the pregnant leach solution (PLS). The waste rock samples showed a similar degree of leaching when the solution chemistry was analysed, despite having different sulphide content. However, when metabolic activity of the micro-organisms on the mineral surface was measured, greater activity was seen with higher sulphide content. This data informs an ongoing study to establish a flow-through configuration of the biokinetic test for ARD prediction accounting for both leach solution and microbial-mineral interaction as well as differing kinetics of acid-neutralising and generating reactions to enable the refinement of the current batch method.

• Periodical: Solid State Phenomena (Volume 262)
• Pages: 228-232
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.262.228
• Online since: August 2017
• Authors: Didi Makaula, Robert J. Huddy, Marijke A. Fagan-Endres, Susan T.L. Harrison*
• Keywords: Biokinetic Test, Isothermal Microcalorimetry, Microbial Colonisation, Waste Rock

References

[1] A. Parbhakar-Fox, B. Lottermoser, D.J. Bradshaw, Cost-effective means for identifying acid rock drainage risks: integration of the geochemistry-mineralogy-texture approach and geometallurgical techniques, The Second AusIMM International Geometallurgy conference / Brisbane, QLD, 30 September - 2 October (2013).

[2] D. Duncan, A. Bruynesteyn, Determination of acid production potential of waste materials, Metallurgy Society, AIME (1979) AIME, Littleton, CO 79-29.

[3] A. Hesketh, J.L.B. Broadhurst, C.G. Bryan, R.P. van Hille, S.T.L. Harrison, Biokinetic test for the characterisation of AMD generation potential of sulfide mineral wastes, Hydrometallurgy. 104 (2010) 459-464.

DOI: 10.1016/j.hydromet.2010.01.015

[4] J.L. Broadhurst, C.G. Bryan, M. Becker, J. Franzidis, S.T.L. Harrison, Characterising the acid generating potential of mine wastes by means of laboratory-scale static and biokinetic tests, In: International Mine Water Association Colorado, USA, (2013).

[5] P. Hlongwane, The influence of solid loading and particle size on the characterisation of sulphide containing ores using the Biokinetic test, MSc thesis, Chemical engineering, University of Cape town, (2015).

[6] A.K.B. Opitz, M. Becker, J.L. Broadhurst, D.J. Bradshaw, S.T.L. Harrison, The biokinetic test as a geometallurgical indicator for acid rock drainage potentials, The third ausimm international geometallurgy conference, Perth, WA 15–16 June (2016).

[7] A.K.B. Opitz, S.T.L. Harrison, The Effect of the Inoculum Concentration on the Biokinetic Test for Characterising Acid Rock Drainage (ARD), Biohydrometallurgy 16', MEI, Ed. Falmouth, UK, (2016).

[8] C.G. Bryan, A study of the microbiological populations of mine wastes, PhD thesis, School of Biological Sciences, University of Wales, (2006).

[9] I.E. Ngoma, T.V. Ojumu, S.T.L. Harrison, Investigating the effect of acid stress on selected mesophilic micro-organisms implicated in bioleaching, Miner. Eng. 75 (2015) 6–13.

DOI: 10.1016/j.mineng.2015.02.007

[10] J.A. Muñoz, D.B. Dreisinger, W.C. Cooper, S.K. Young, Silver-catalyzed bioleaching of low-grade copper ores. Part I: Shake flasks tests, Hydrometallurgy. 88 (2007) 3 – 18.

DOI: 10.1016/j.hydromet.2007.01.007

[11] D.X. Makaula, R.J. Huddy, M.A. Fagan-Endres, S.T.L. Harrison, Using isothermal microcalorimetry to measure the metabolic activity of the mineral-associated microbial community in bioleaching, Miner. Eng. 106 (2017) 33 – 38.

DOI: 10.1016/j.mineng.2016.12.012