Effect of air dissolved in water on simultaneous ultrasonic-assisted coal flotation

ABSTRACT

The effect of air dissolved in natural water on simultaneous ultrasonic-assisted coal flotation was investigated combined with flotation tests, froth properties and flotation kinetics models analysis. Compared with degassed water, the better flotation performance was obtained in natural water when ultrasound was not used or ultrasonic power was lower than 200 W. For the low ultrasonic power (< 200 W), the air dissolved in natural water promoted the precipitation of bubbles to obtain the small bubble and thick froth layer, which was beneficial to improve the coal flotation. However, the froth properties in natural water were almost the same as those in degassed water if the ultrasonic power was reached to 200 W, indicating that the performance of ultrasonic flotation in degassed water was almost the same as that in natural water. In addition, the processes of ultrasonic-assisted coal flotation in natural and degassed water could be described by the second-order model with rectangular distribution of floatability. The ultrasonic flotation rate of natural water was twice than that of degassed water. Hence, these above results made a contribution to improve the performance of ultrasonic-assisted coal flotation in natural water.

KEYWORDS:

• Ultrasound
• natural water
• degassed water
• froth properties
• flotation kinetics

Highlights

• Air dissolved in water affecting coal flotation was related to ultrasonic power.

• Higher concentrate yield of ultrasonic flotation was achieved in natural water.

• Air dissolved in water reduced bubbles size and increased froth layer height.

• Air dissolved in natural water doubled the rate of coal ultrasonic flotation.

Additional information

Funding

This work was supported by the Fundamental Research Funds for the Central Universities [2017CXNL04].

Notes on contributors

Yuqiang Mao

Yuqiang Mao is a doctoral candidate at China University of Mining and Technology.  He mainly studies the ultrasonic-assisted coal flotation and pore wetting of porous minerals.

Xiangning Bu

Xiangning Bu is a postdoctoral fellow at China University of Mining and Technology. He aims to improve the flotation performance of fine/ultra-fine particles using hydrodynamic cavitation or ultrasound.

Huaizhi Shao

Huaizhi Shao is a PhD from China University of Mining and Technology.

Shaoqi Zhou

Shaoqi Zhou is a graduate student at China University of Mining and Technology. His study is  to improve the flotation of ultra-fine particles by hydrodynamic cavitation.

Guangyuan Xie

Guangyuan Xie is a professor at the School of Chemical Engineering of China University of Mining and Technology. He mainly studies the high-efficiency separation technology of fine coal.