Use of Ultrasound to Enhance Flotation Performance: Flotation Cleaning of Oil Shale after Ultrasonic Pre-Treatment

This study aims at determining the contribution of ultrasonication to conventional flotation. In this regard, enhancing the performance of flotation cleaning of an oil shale sample was attempted using ultrasonic pre-treatment. The use of the excitation effect through ultrasonication was investigated towards fine and ultra-fine ash making-inorganic particles that are clogged in pores/voids or are attached as coatings on surfaces of larger entities. Ultrasonic pre-treatment was applied prior to flotation at a range of ultrasonic power levels and for different durations of ultrasonication. This pre-treatment proved to be useful in improving the extent of ash rejection and producing a cleaner oil shale concenrate at remarkable combustible recoveries. Conventional flotation cleaning (without ultrasonic pretreatment) could reduce the ash content of the cleaned oil shale from 34.76% to 16.82. Ultrasonic-aided flotation resulted in further decrease in ash to 11.82 % at 82.66 % combustible recovery. Comparative XRD and SEM analyses showed that inorganic particles in the pores/voids or attached to the surfaces of larger particles were effectively removed after ultrasonic pre-treatment. This has significantly improved the liberation between organic and inorganic entities, leading to a more effective separation process through fllotatio