A technique for measuring flotation bubble shell thickness and concentration

Froth structure is known to significantly affect flotation performance. How ever, little information is generally available on the loading of solids on bubbles in the froth. It has been noted in foam studies that the bubble sh ell is very viscous and distinctly separate from the inter-bubble lamellae. In froth flotation, these bubble shells contain hydrophobic solids selecti vely attached, while the inter-bubble lamellae contain both hydrophobic and hydrophilic solids, which ave non-selectively entrained. In this technical note we introduce a measurement technique to measure directly the bubble s helf thickness and solids concentration. This measurement allows the collec tion of particles due to attachment to bubbles and from transport in the in ter-bubble lamellae to be estimated. It is found that an increase in the su rfactant concentration decreases the solids concentration in the bubble she ll. The average bubble shell thickness closely corresponds to the particle size, which is in agreement with previous studies. (C) 2000 Published by El sevier Science Ltd. All rights reserved.