Frothers: from fundamentals to practice

Frothers provide three key functions: maintaining small bubble size, reducing bubble rise velocity, and contributing to froth stability. Studies have linked these functions to frother structure. The first two will be the focus of a keynote lecture at Flotation '25 by Jim Finch, Hatch Professor Emeritus in Mining and Metallurgical Engineering at McGill University, Canada. 

Bubble size is tracked by critical coalescence concentration (CCC) and rise velocity by the concentration at minimum velocity (CMV). Both measures will be briefly explained and CCC and CMV shown to be related. Two theories help link to frother structure, the Marongoni effect and the hydration effect. Including impact of molecule conformation and H-bonding on molecule transport either theory provides an explanation. For alcohols, as an example, the link shows an advantage of branched over straight chain structures. Hydration theory does have an advantage: through ordering water it provides an interpretation of why different size bubbles can rise at the same speed dependent on frother type. Evidence that the volume of water carried per bubble varies with frother type will be presented, water transport aiding froth stability and influencing frother choice.

Jim Finch is one of the most well known figures in mineral processing, being ranked #3 in the world by ScholarGPS. MEI is proud to have him as a consultant to the flotation conferences and I had the pleasure of interviewing him for the blog in 2015. A graduate of Birmingham University, UK, he has been associated with McGill University since 1973. He is the co-author of two books Column Flotation (1990) and 8th Edition of Wills’ Mineral Processing Technology (2016). 

Among his many awards are the SME Antoine Gaudin Award and the IMPC Lifetime Achievement Award and he is currently a CIM Distinguished Lecturer, an honour he holds for the second time. He was General Chair of the XXVIII IMPC, Québec City, 2016.

Jim Finch with Lucas Pereira at Flotation '23

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