SEM and EDS observations of carrollite bioleaching with mixed culture of acidophilic bacteria

摘要

Bioleaching of high purity carrollite minerals with mesophilic bacteria has been done with a parallel high-resolution observations in scanning electron microscopy (SEM) aiming to provide evidence about the interaction pattern between carrollite and bacterial cells. A bacterial consortium involving three different acidophilic chemolithotrophs was adopted and the evolution of the surface topography of the mineral with leaching time was followed. The SEM views coupled with X-ray EDS analysis indicated that bacterial adhesion takes place on the mineral surface resulting in formation of dissolution pits having different morphology. Enhanced concentration of ferric iron could be assumed in vicinity of the zones where mineralized polymer substances are precipitated. We infer that carrollite dissolution is governed by cooperative bioleaching involving oxidation induced from bacteria attached to the surface and non-specific oxidation by bio-regenerated ferric iron.