Collision and adhesion process of air bubbles on coal surface

In slime flotation,the flotation of coal is closely related to its surface wettability. In this paper,the lignite and coking coals with different surface wettability are investigated. The formation process of the three phases contact during the collision between bubble and coal surface is studied. First,the differences of the two kinds of coal interface properties are analyzed. At the same time,the I-SPEED 3 high speed dynamic camera is used to record and analyze the micro process of the collision and adhesion between air bubble and coal surface. Results show that under a certain con- dition of collision velocity,the bubble and coal surface should go through several collision process,contact-bounce-con- tact,and finally form the gas-liquid-solid three phase contact periphery. Three-phase contact surrounding is formed in the coking coal surface with bubble after the second collision,and the area is 8． 2 mm2 . Three-phase contact surround- ing is formed after 3 times of collision in the surface of lignite,and the bubble in coal surface spreading area is 4． 6 mm2 . The greater contact angle of coal surface is,the shorter the three-phase contact formed around the time will be, and the greater bubble in the spreading area of coal surface will be. From the microscopic point of view,the effect of surface hydrophobicity of coal on the process of bubble mineralization is verified.