基于离散元法的浮选煤粒运动状态研究OA

The mutual movement between fine coal particles and bubbles is difficult to fully clarify due to its microscopic nature and complexity.In this paper,a simulation program for coal particles with different ash contents moving on bubbles was constructed by the discrete element method.The movement states of coal particles with particle sizes of 74 μm‒125 μm and ash contents of 14%and 85%on bubbles under still water conditions were simulated,and verified by an independently built coal particle-bubble interaction behavior observation device.The simulation results show that the movement behavior of coal particles on bubbles can be divided into three stages:free settling stage,liquid film drainage stage(1.speed reduction stage;2.sliding along the bubble stage;3.rupturing the liquid film to form a three-phase contact line stage),and sliding along the three-phase contact line(TPCL)stage.Coal particles approach the bubble at the terminal velocity of free settling.When approaching the bubble,the speed is reduced due to liquid film drainage.The 14%ash content coal particles have a complete liquid film drainage process,with a liquid film drainage time of 1 225 ms and a speed reduction time of 557 ms when approaching the bubble.The 85%ash content coal particles cannot form a complete liquid film drainage process,and the speed reduction time when approaching the bubble is 169 ms.After contacting the bubble,the speed of the coal particles drops sharply to the minimum and the particles slide along the surface liquid film.During the sliding process,the 14%ash content coal particles rupture the liquid film on the bubble,and the speed changes suddenly,forming a three-phase contact line(TPCL)and sliding along the bubble.The speed reaches the maximum(2.37 mm/s)at the horizontal symmetry axis of the bubble and finally stays at the bottom of the bubble;the 85%ash content coal particles accelerate sliding on the liquid film,reaching the maximum speed(8.95 mm/s)at the horizontal symmetry axis of the bubble and detaching from the horizontal symmetry axis.The test results show that the ash content is negatively correlated with the liquid film drainage time of the particles and positively correlated with the sliding speed.