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Froth Flotation/Dissolved Air Flotation: Bridging the Gap
There are two separate flotation traditions: that practiced by Mineral Processing Engineers in the Minerals Industry and that practiced by Chemical, Civil and Sanitary Engineers in domestic and industrial waste treatment. In general, induced air flotation (especially froth flotation) is used in mineral processing, while in wastewater treatment, either dissolved air or induced air flotation may be employed. In mineral processing the separation is usually a solid-solid separation in water while in wastewater treatment the separation is usually solid-liquid or liquid-liquid. The purpose of this United Engineering Foundation conference was to bring scientists and engineers from both traditions together and start a dialog between the two groups. Over 40 engineers and scientists from 11 different countries participated in the meeting. A total of 36 papers were presented.
The sessions were:
In the overview sessions differences in practice requirements in the two traditions were considered. In particular, the different bubble size requirements were elucidated and the possible flotation machine alterations that could adjust bubble size production were discussed. In another significant paper the invention and application of bubble accelerated flotation devices were discussed. The bubble acceleration is required for very small bubbles, which in traditional machines rise so slowly as to limit machine capacity. Overall, a number of presentations discussed new flotation machine developments in both wastewater and mineral flotation. A number of papers considered the interaction of bubbles and particles on both micro and macro scales from both practical and theoretical points of view.
Other interesting contributions included research into froth drainage characteristics as a function of the hydrophobicity of gangue minerals in a column flotation froth, adsorbing particulate flotation for metal ion removal from waste water and the use of flotation to help remediate acid mine drainage waters. The role of surfactants in de-inking flotation was considered in two different papers. In mineral flotation, two complimentary papers explored the mechanisms and practical applications of soluble salt flotation. Other papers discussed some advances in phosphate and coal flotation.
The conference should be considered as a beginning dialog between the two groups of engineers and scientists. It is hoped that future conferences on "bridging the gap" will produce many examples of actual integration of the two traditions in both wastewater treatment and mineral flotation.
Prof. R.W. Smith, University of Nevada-Reno, USA. Email: email@example.com
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