Study On The Effect Of Oil Collector On The Interaction Behavior Between Coal Particle And Bubble And The Related Mechanism

Flotation is an important method of coal separation.The most important step in the flotation process is the mineralization of bubbles,which is the result of the interaction between coal particles and bubbles.In order to improve the efficiency of bubble mineralization,non-polar oil is widely used in the flotation process.Therefore,this article focuses on the study of the influence of oil collectors on the interaction between coal particles and bubbles.First,the coal particle bubble adhesion device was used to study the dynamic behavior of the collision and adhesion between coal particles and bubbles.Different types of oils are used to modify coal particles,and the mechanism of oily collectors is analyzed by comparing the differences in adhesion behavior between coal particles and air bubbles.Secondly,the adhesion strength of coal particle-bubble aggregates modified by different oils was analyzed by using a loudspeaker vibration device.Finally,through the piezoelectric ceramic double crystal cantilever beam mechanics test device,the whole process of collision,adhesion and separation of coal samples and bubbles after different oil modification was obtained,from the study of bubbles and oil film deformation and force.In-depth analysis of the mechanism of oil in the coal particle bubble adhesion process.The research in this article is of great significance for promoting the development of flotation technology and further enriching and perfecting the basic theory of flotation.(1)The results of dynamic research on the adhesion process of coal particles and bubbles show that after coal particles approach the bubbles at the end of free sedimentation speed,the speed drops to the lowest at the moment of collision with the bubbles.After moving along the bubble,the velocity gradually increases until the velocity reaches the maximum at the position of the bubble's equator,and finally slips to the bottom of the bubble and stably adheres to the bottom of the bubble or falls off below the bubble's equator.Experiments have found that the smaller the collision angle,the easier it is to adhere;and when the collision angle is greater than about 42°,the coal particles will eventually slip off.This is because the adhesion of coal particles and bubbles requires the rupture of the hydration film.When the collision angle is large,the kinetic energy provided by the coal particles is not enough to complete the process,causing the coal particles to slip.(2)After the coal sample is modified by dodecane and kerosene,the contact angle becomes larger,and after being modified by oleic acid,the contact angle becomes smaller.However,the dynamic study of the coal particle bubble adhesion process using the three kinds of oil-modified coal particles found that the average adhesion time of the coal particles and the bubbles after the three oil-modified coal particles became shorter,and the adhesion angle became smaller.The adhesion efficiency becomes higher.Among them,dodecane is the most effective,followed by kerosene,and then oleic acid.The modified coal particles with irregular shapes were also studied,and it was found that the coal particles modified by non-polar oil tended to adhere to the bubbles with a flat surface,while the coal particles and bare coal modified by polar oil,its tip will attach to the bubble The surface contact of the non-polar oil modified coal particles should be due to the hydrophobic non-polar oil film that can minimize the contact with water at this time;because oleic acid is a polar oil,in order to achieve the most stable state,It is necessary to adjust the position of its own group so that the polar group is in contact with water,and one end of the non-polar group is in contact with bubbles.This may be the reason why the oleic acid-modified coal particles are in sharp contact with the bubbles.The pointed contact of bare coal is to satisfy its static contact angle of 85°.(3)Introduce the classical EDLVO theory to calculate the interaction potential energy between bubbles and coal particles,bubbles and non-polar oil.It is found that the attraction between the non-polar oil and the bubbles is greater than the attraction between the coal particles and the bubbles,indicating that after the coal particles are modified by the non-polar oil,the attraction between the bubbles and the non-polar oil will make the surface of the coal particles The non-polar oil film preferentially adheres to the air bubbles.(4)When studying the stability of coal particle-bubble aggregates modified by different oil-based agents through speaker vibration,it is found that the stability of coal particle-bubble aggregates modified by different oil collectors has nothing to do with their adhesion effects.Combined with the dynamic contact angle of the oil droplets on the coal surface,it is found that the coal particle-bubble adhesion strength is related to the viscosity of the oil used.The greater the viscosity,the less likely it is for the coal particles to detach from the surface of the bubbles.(5)The attachment test between coal particles and bubbles modified by dyed oil droplets found that after the coal particles were separated from the bubbles,the oil droplets remained on the bubbles and coal particles.It shows that the adhesion of coal particles and bubbles is the leading role of oil on the surface of coal particles,and the adhesion of bubbles and coal particles is produced by the "oil bridge".The separation of air bubbles and coal particles is also caused by the fracture of the oil bridge.(6)Measure the force in the process of coal particle-bubble interaction through the home-made piezoelectric ceramic double crystal cantilever beam mechanics test device,and observe the whole process with a high-speed camera.It was found that the approach process can be divided into two stages: one is the drainage of the liquid film under the action of hydraulic dynamics and surface forces,and the other is the spreading and adhesion after the liquid film ruptures to form a three-phase contact line.The separation of coal and bubbles is also divided into two stages: in the first stage,the bubbles stretch and deform,and the contact angle of the bubbles on the coal becomes larger,but the three-phase wetting line remains unchanged until the advancing contact angle is reached;During the phase,the contact angle remains unchanged,and the three-phase contact periphery decreases to the final separation.(7)Using piezoelectric ceramic double crystal cantilever beam mechanics testing device to study the interaction between coal and air bubbles modified by different agents.The results showed that the induction time of coal and bubbles after modified by non-polar oil,kerosene and dodecane was significantly reduced,and the spreading time of the three-phase contact line was also significantly shortened;the maximum separation force of bubbles and coal was related to the viscosity of the agent used related.This further proves that the separation of oil-modified coal particles and air bubbles is caused by the fracture of the oil bridge.Through microscope observation,it is found that the separation of bare coal and bubbles may not require the splitting of bubbles,but is completely desorbed directly from the coal surface.