Contact Angles in Flotation

Schematic of 3-Phase System

Since the invention of froth flotation in 19th century, many laboratories are committed to both fundamental and applied research on collection of particles by dispersed gas bubbles in aqueous solutions of electrolytes, especially those working on processing of natural resources. However, in spite of tremendous progress made in characterization of particles and their surfaces and understanding the particle-bubble interactions, supported with detailed recordings of gas bubble attachments to both bulk specimens and particles, the flotation process remains poorly correlated with the wetting characteristics of particle surfaces. In fact, the contact angles used frequently to describe wettability of mineral surfaces remain among the most controversial, misunderstood and misinterpreted values in mineral processing literature. Contrary to wide-ranging beliefs, in the new contribution by Prof. Drelich (Michigan Tech) and Prof. Marmur (Technion, Israel) argue that neither the methodology of contact angle measurements nor selection of contact angles important to the particle flotation process are properly executed when analyzing flotation process. In their new paper published in Surface Innovations and entitled Meaningful contact angles in flotation systems: critical analysis and recommendations, the authors provide a brief personal prospective on some of the misconceptions on contact angles and the importance of additional fundamental studies in the area of mineral particles flotation.

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