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Effect of ultrasonic standing waves on flotation bubbles
Lizhang Jin1, Weidong Wang1, Yanan Tu1
1School of Chemical and Environmental Engineering, China University of Mining&Technology (Beijing), Beijing 100083, China.
Ultrasonics Sonochemistry
|February 23, 2021
Summary
Ultrasonic flotation effectively separates fine coal using standing waves. A 100 kHz frequency optimized bubble aggregation, leading to the highest clean coal yield and recovery.
Area of Science:
- Mineral Processing
- Acoustics
- Chemical Engineering
Background:
- Ultrasonic flotation is a promising technique for fine coal separation.
- Understanding the role of ultrasonic standing waves is crucial for process optimization.
Purpose of the Study:
- To investigate the impact of different ultrasonic standing wave frequencies on fine coal flotation.
- To elucidate the dynamic interactions between bubbles and coal particles under ultrasonic influence.
Main Methods:
- Utilizing high-speed videography to observe bubble and coal-bubble dynamics.
- Employing image processing for statistical analysis of bubble aggregates.
- Conducting ultrasonic flotation experiments at varying frequencies (80, 100, and 120 kHz).
Main Results:
- Standing waves induced rapid formation of bubble (450 ms) and coal-bubble (20 ms) aggregates via Bjerknes force.
- 100 kHz frequency resulted in a higher number of aggregates and smaller bubbles compared to 80 and 120 kHz.
- The 100 kHz frequency achieved the highest clean coal yield (35.89%) and combustible recovery (45.77%).
Conclusions:
- Ultrasonic standing waves enhance fine coal flotation by promoting bubble-coal particle aggregation.
- Cavitation bubbles act as mediators, entrapping and entraining coal particles.
- 100 kHz is identified as the optimal frequency for maximizing flotation efficiency in this study.
Keywords:
Bubble aggregationEntrapment and entrainmentStanding wavesStanding waves ultrasonic flotationMore Related Videos
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