Investigation of Flash Flotation Technology Utilizing Centrifugal Forces and Novel Sparging Methods
Rowley, Dylan Mark
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A new processing technique, centrifugal flotation, has been developed in recent research projects to overcome the large residence times and fine particle limitations of traditional flotation technologies. The major innovation in the area of centrifugal flotation is the Air Sparged Hydrocyclone (ASH), which has proven capabilities in achieving quality products at specific capacities greater than traditional flotation methods. However, the ASH technology ultimately suffers from sparger plugging problems. Therefore, three unique flotation cyclone designs were developed utilizing external sparging systems and control features to float fine coal. The objective of each design was to create a system that mimics the behavior of the ASH technology, while providing advantages in bubble generation and retention time requirements. The evaluation of the three designs provided evidence towards the development of an efficient centrifugal flotation technique. Evaluation of a flotation cyclone with an external Cavitation Tube yielded a single-stage product with an ash content of 4.41% and a 45% recovery rate in a retention time of 0.66 seconds. However, the system required 16 minutes to meet comparable flotation yields and recoveries. The third design achieved a multiple-stage product of 11.32% ash at a 55% recovery in 20 minutes. These two designs provided low yield, high grade products, but rejected a high percentage of hydrophobic particles and required high retention times to meet typical flotation standards. In addition, these designs suffered by requiring high frother concentrations and recovery could not be increased through increased aeration due to design limitations.
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