Mobility and transport of copper(II) influenced by the microbial siderophore DFOB: Column experiment and modelling.

Acid Cu leaching from the European Kupferschiefer ore deposits is a challenge e.g. due to its high carbonate content. In this study, we investigated the transport behaviour of Cu under conditions related to a biohydrometallurgical leaching approach using neutrophil microorganisms in neutral to slightly alkaline solutions. We studied the effect of the microbial siderophore desferrioxamineB (DFOB) as a model leaching organic ligand on Cu mobility in column experiments with kaolinite. The results revealed that DFOB strongly enhances Cu mobility. The breakthrough of Cu occurs considerably earlier in the presence of DFOB than in the absence of the organic ligand. Furthermore, complete elution of Cu was observed at 5 pore volume exchanges faster compared to elution with deionized water. The established geochemical transport model shows good agreement with the experimental data and suggests a maximum efficiency at a Cu to DFOB molar ratio of 1:1. In addition, results of modelling revealed that in the absence of the ligand, a pH increase from 6.5 to 8.5 significantly retarded Cu breakthrough, whereas in the presence of DFOB, Cu breakthrough curves were nearly insensitive to pH changes and close to the breakthrough curve of a non-reactive tracer.