Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Froth flotation is one of the most important techniques in the mining industry for the efficient separation of particles with sizes between 10 µm and 200 µm. The separation process is based on the difference in particle wettabilities, as hydrophobic particles attach to a gas bubble and are recovered in a froth, whereas hydrophilic particles tend to stay in the pulp. Although, the wettability is the most prominent separation feature, the micro processes that occur in the pulp and in the froth zone include complex interactions between the particles and the bubbles and also other particle properties, such as size, morphology, surface energy or the dispersion state have an impact on the separation.
Low ore grades and very fine composite particles in electronic devices are forcing the industry to adapt and improve existing flotation techniques to the processing of ultrafine particles (< 10 µm), as the material needs to be milled down to finer size fractions to obtain sufficient liberation of the valuable minerals. For that reason, the project “MultiDimFlot”, which is part of the German research foundation priority programme DFG-SPP 2045 “MehrDimPart”, aims at developing a method for the separation of ultrafine particles (< 10 µm) based on multiple particle properties.
A novel separation apparatus is used that combines the advantages of a mechanical flotation cell that comes with a high particle-bubble collision rate (thus a high recovery) with those from a flotation column with a fractionating effect due to its deep froth (thus a high grade). An academic particle system, consisting of glass spheres, glass fragments and glass fibres as the valuable material and magnetite as the gangue material is used, whose particle properties are studied in depth. These investigations will help to further understand the behaviour of ultrafine particles during flotation and how certain particle properties affect the separation process. Furthermore, the possibilities and limitations of different analysis techniques, e.g. coupled SEM-EDX, flow cytometry or inverse gas chromatography are investigated for their use in ultrafine particle characterization.