Frother-depressant interactions in two and three phase systems

The quality and stability of the froth phase in flotation is mainly attributed to the amount and degree of hydrophobicity of solid particles reporting to the froth phase. These two parameters are influenced by the type and quantity of collectors and depressants added to the system. Frothers also influence the quality and stability of the froth mainly by affecting its water content.Decoupling and identifying the effects caused by different flotation reagents is of primary importance in understanding flotation processes. Frothers and their influence on bubble formation and foam/froth formation have been studied extensively. The effect of collectors and depressants has also been investigated. However, no research has been done on the combined effect of depressants and frothers to identify the inter-reagent interactions taking place in the flotation process.This study examines the effect of two polymers, namely Stypress 504, a modified guar gum, and Depramin 267 a CMC, on the foaming and frothing properties of solutions containing Dowfroth 200 frother. These polymers are used as depressants in the flotation of platinum bearing minerals. The frothing properties were evaluated through maximum froth height measurements, froth collapse studies and visual observation of the froth structure in air-liquid and air–liquid–solid systems.The experiments showed that the presence of depressants had a significant effect on the foaming/frothing properties of the studied frother. Both the maximum froth height and the froth structure were altered. In order to identify the mechanism of the inter-reagent interaction, bulk and surface viscosity measurements and surface tension measurements were also performed.

Research highlights
► Polymeric depressants affect the foaming properties of the Dowfroth 200 frother.
► Foam formation enhanced in presence of Stypress 504 and Depramin 267.
► Depramin 267 increased bulk viscosity, slowed drainage and inhibited coalescence.
► Stypress 504 changed the surface rheology at low concentrations.
► Surfactant-polymer complexes are likely to form in multi-reagent systems.