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The Mechanism of Floc Formation by Hydrodynamic Cavitation and Its Application on Fine Particle Flotation
- Author / Creator
- Huang, Hao
In recent decades, hydrodynamic cavitation has been used to enhance fine particle flotation recovery in mineral engineering. Such an increase was mainly attributed to the generation of flocs/aggregates of fine particles during the hydrodynamic cavitation process. However, the mechanism of floc formation in hydrodynamic cavitation still remains unclear. This study aims to fill this knowledge gap regarding the agglomeration mechanism of fine particles in hydrodynamic cavitation.
Fine molybdenite particles with the diameters less than 37 μm were investigated with the cavitation system. The optimized geometry Venturi tube investigated in previous studies of our research group was applied in a hydrodynamic cavitation system for microbubble generation and floc formation. Floc size was measured to study the relationship between the cavitation intensity and flotation efficiency. Under cavitation with inlet air injection, floc size increased to 140 μm efficiently. Microscope images of generated flocs were captured to examine the structure. It was found that cavitated bubbles acted as the bridges between particles in the floc structure. Zeta potential distribution was measured to investigate the interaction between microbubbles and fine particles. Strong attachment of microbubbles and particles were demonstrated in cavitation treatment.
Hydrodynamic cavitation was also applied in micro-flotation of fine particles to study the effect of flocs in the mineral flotation. An increase of 20% in recovery of fine molybdenite was achieved after cavitation with inlet air injection. Fine silica particles in the same size range were used as a comparison. No significant increase of fine silica recovery was found. This observation indicates that cavitation predominantly affects hydrophobic particles based on contact angle results. At last, the flotation of the mixture of molybdenite and silica was investigated to demonstrate the selectivity of hydrodynamic cavitation in mineral processing.
- Graduation date
- Fall 2018
- Type of Item
- Master of Science
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