Variable parameter optimization and experimental study of jet mixing device

The jet mixing device is widely used in various fields, and its parameters have an important influence on the ejection performance, particle movement and action mechanism. But the variable parameters of the jet mixing device used in the slime flotation field lack systematic optimization. In order to optimize the variable parameters of the jet mixing device, a jet mixing test system was set up to explore the influence of key parameters such as area ratio Ar, throat-nozzle distance Le, the length of throat tube L, opening degree of the ejection tube γ and nozzle outlet velocity V on the ejection performance. Based on the parameter optimization value of the physical model, the action mechanism of the jet flow field on the material was studied by adjusting the test system, and the stripping ability of fine mud on coal surface by jet flow field was investigated. A high-speed camera was used to capture the entrainment and breakage of the jet stream to the ejection bubble. The migration law of bubble size was revealed by laser particle size analyzer. The results show that: when the area ratio Ar = 3.24 and the throat-nozzle distance Le = 0.56Dh (Dh is the diameter of the throat tube), the ejection flow ratio q reached the maximum. Considering the ejection capacity and linear loss of the device, when the length of throat tube L = 9Dz (Dz is the diameter of the nozzle) and nozzle outlet velocity ≥15 m/s, the ejection performance is the ideal. The flow rate of the ejector fluid is proportional to the opening degree of the ejection tube. The ejection velocity is limited by the jet velocity (which is represented by the nozzle outlet velocity). When the jet velocity reaches 15m/s, the ejection velocity reaches the upper limit. Based on the optimal ejection performance parameters, the separation and dispersion effect of once jet mixing is equivalent to the mixing device of laser particle size analyzer at 500 r/min speed of 4~4.5 min. EDS was used to test the changes of C, O, Al and Si elements in materials before and after jet action, which verified the stripping ability of the fine mud cover by jet action. When the jet velocity reaches 7.2 m/s, the bubbles are instantly crushed into smaller bubbles, of which more than 90 % are smaller than 45 μm. © 2023 Coal Science and Technology. All rights reserved.