Identifying nanoscale ferrihydrite in hydrometallurgical residues

The identification of a disordered nanoscale material such as ferrihydrite in a heterogeneous sample environment, as is typically the case in a hydrometallurgical residue, requires a rigorous multifaceted characterization approach. An example of this is the identification of ferrihydrite in paragoethite process residues generated in zinc refining. In a pure-form ferrihydrite, a poorly crystalline iron(III) oxyhydroxide possesses a characteristic powder x-ray diffraction profile consisting of very broad low-intensity reflections. However in coexistence with crystalline material, the diffraction profile may be masked, lost in the background noise, and easily overlooked. By using several characterization approaches in combination, ferrihydrite can be identified in a hydrometallurgical residue with a higher degree of confidence than can be achieved by the application of a single technique.