The influence of the particle properties of size, shape and surface energy on the separation of ultrafine particles via froth flotation using multidimensional tromp maps for evaluation

Froth flotation is one of the most important beneficiation techniques in the mining industry. For particles with sizes ranging from 10 μm to 200 μm it efficiently separates the valuable minerals from unwanted gangue according to their differences in the particle wettabilities. For an efficient flotation separation of ultrafine particles (< 10 μm) existing techniques need to be adapted and improved in order to maintain an efficient separation. Furthermore, there is a potential in separating particles not only by wettability (surface energy) and size but also by their morphology. To investigate this is the aim of this project, which is part of the German research foundation priority programme DFG-SPP 2045 “MehrDimPart”. A well-characterised model particle system consisting of ultrafine size fractions of glass particles as the floatable and magnetite as the non-floatable fraction is used for this study. The wettability of the glass particles is modified via an esterification reaction using alcohols with differing chain length and the resulting wettability states are analysed using inverse gas chromatography as well as analytic particle solvent extraction. Information on the particle size and shape are obtained via a combination of laser diffraction and microscopic analysis. All separation tests are carried out in batch mode using a novel separation apparatus, specifically designed for the flotation of ultrafine particles by combining advantages from machine-type froth flotation and column flotation and the separation process is evaluated using multidimensional tromp maps. This investigation will help to further understand the recovery of particles with variable properties in flotation, as well as other separation processes. In this way, the separation of ultrafine particles will become more efficient, which will play an important role in the recycling of secondary materials and in the processing of ultrafine particles in the chemical industry.