Flotation Fundamentals

Froth flotation is a key separation process in mineral processing. Although it is implemented in large industrial cells, its performance is governed by subprocesses that occur at the scale of bubbles, particles, and fluid interfaces. Our group investigates these flotation-relevant subprocesses under controlled conditions. We study how bubbles, particles, surfactants, collectors, frothers, salts, and ultrafine particles interact, and how these interactions determine particle attachment and detachment, froth stability, and separation selectivity.

What we study

Flotation performance depends on coupled physicochemical and hydrodynamic subprocesses at fluid interfaces. Surface chemistry, particle size, wettability, hydrodynamics, and interfacial mobility all influence whether particles collide with and attach to bubbles, whether bubbles coalesce or remain stable, and whether froths form and persist.

Rather than treating flotation only as a unit operation, we analyse the subprocesses that control its performance. This allows us to connect subprocess-level dynamics with flotation outcomes such as particle recovery, film rupture, bubble stability, froth behaviour, and reagent efficiency.

Our approach

We use controlled model experiments and complementary methods to investigate flotation subprocesses under well-defined conditions. This enables us to resolve governing mechanisms in complex multiphase systems and to provide a mechanistic basis for improved flotation technologies. Our work focuses on four main research areas:

1- Bubble-particle attachment We investigate how particles attach to bubbles, with particular attention to particle size, wettability, surface roughness, hydrophobicity, flow conditions, and chemical additives. This is especially important for fine and ultrafine particles, which are often difficult to recover efficiently.	2- Thin films and bubble-bubble coalescence We study the drainage, deformation, rupture, and stabilization of thin liquid films between bubbles, and between bubbles and particles. These processes control bubble coalescence, bubble size, gas dispersion, froth lifetime, and attachment efficiency.
3- Interfacial flow We examine how adsorbed materials such as surfactants, frothers, collectors, and particles modify flow near fluid interfaces. Interfacial mobility strongly affects film drainage, bubble–particle attachment, coalescence, and mass transfer.	4- Surfactant-particle interactions We investigate how surfactants, particles, and other surface-active species form mixed interfacial layers. These layers can modify surface tension, interfacial elasticity, film stability, and surface mobility, influencing key flotation subprocesses.

From fundamentals to flotation technology

By linking interfacial mechanisms to flotation performance, our research supports the development of more selective, efficient, and sustainable flotation processes. This includes improved reagent strategies, better control of fine and ultrafine particles, and more efficient use of water, energy, and raw materials.