• Hedayatkhah, Abolghasem
• Rickard, William
• Dodd, Aaron
• Putnis, Andrew
• Watkin, Elizabeth
• Corbett, Melissa
• Eksteen, Jacques
• Fathollahzadeh, Homayoun
• Sun, Xiao

Abstract

Microbial activity results in changes on the surface and subsurface of metal bearing minerals. These changes can be both physical and chemical. While this has been studied for sulfide minerals, no study is available on phosphate minerals. Klebsiella aerogenes was used to study such changes on the surface of monazite, a rare earth phosphate mineral. To minimize the physical imperfections on the surface, samples were fixed in a resin and polished. Moreover, some lamellas (10×10 μm, 1 μm thick) were prepared from the mineral ore using focused ion beam (FIB) microscope from different regions of the polished samples such as rare-earth rich locations and fixed on transmission electron microscopes (TEM) grids. The samples were subjected to biotic or abiotic leaching and surface changes observed and analyzed with TEM, energy dispersive X-ray spectroscopy (EDS), Tescan Integrated Mineralogy Analyzer, and time of flight secondary ion mass spectrometry (ToF-SIMS). Despite minimizing the physical imperfection in both sample groups, microbial attachment to the surface showed no selectivity to mineral composition. TEM and ToF-SIMS analysis showed some physical changes on the immediate subsurface beneath the bacteria. ToF-SIMS showed evidence of possible rare-earth- organic acid complex formation during bioleaching.

Topics

• impedance spectroscopy
• mineral
• surface
• focused ion beam
• transmission electron microscopy
• leaching
• Energy-dispersive X-ray spectroscopy
• resin
• spectrometry
• selective ion monitoring
• secondary ion mass spectrometry
• lamellae