Amphiphilic Siderophores – A group of complexing surfactant bioreagents for the application in froth flotation separation

The consumption of metallic raw materials is constantly increasing. The coverage of demand is getting more difficult, because both primary and secondary raw materials become more and more complex. To find a solution, new approaches will have to be developed, like the combination of biotechnology with classic processing methods.
The idea of this work is the biotechnological production of siderophores for the application as a reagent in conventional froth flotation processes. Siderophores are small organic molecules with a high affinity for binding Fe(III) and to selectively form strong complexes also with other metals. They are produced by microorganisms (aerobic bacteria and fungi) and some plants. Especially the group of amphiphilic siderophores are very interesting. The hydrophilic part, carrying hydroxamate functional groups, is responsible for the selective binding of the metals. Flotation agents produced by the chemical industry with the same functional groups have already been applied successfully in this processing method. It can be suggested siderophores carrying the same and even more selective functional groups are highly potential as ecofriendly collector molecules for flotation and should generally be interesting for the surfactant industry. The molecule’s tail, that is representing the hydrophobic part, gets in contact with the bubble and spares additional chemicals and further working steps for making the target mineral particles hydrophobic.
Besides the biotechnological production of these amphiphilic siderophores, this work includes also interaction studies and flotation experiments of different scales, including bubble pick-up tests, Halimond tube microflotation and batch lab flotation experiments of iron and copper bearing ores.
The application of amphiphilic siderophores as biochemicals in the froth flotation process can change the classic processing method in a more sustainable process – the Bioflotation process. This will reduce the usage of other chemical agents. Moreover, the specific metal binding of siderophores changes flotation in a more purposeful and efficient process and is an important enrichment for the field of Biohydrometallurgy.