| Floatation as one of the dominant mineral processing technology iswidely applied throughout the world, especially in fine size mineralsseparation. As a result, extending the upper particle size limit has far-reachingsignificance. In this dissertation, research on flotation characteristic of coalwith upper size limit to l mm was conducted. The influence of law of physicalconditions on wide grain slime flotation was inspected. Furthermore, throughthe narrow particle flotation kinetics experiments, the effects of rotationalspeed in flotation and air-flow rate on flotation dynamic kinetic constant andvisual analysis of flotation dynamic were investigated. Theoretical analysisdemonstrates the size of different particles, density in different impeller speeds,aeration rate and the impact on the flotation behavior. Also, this paperexamines the relationship between the flotation rate constant and particles’density and size. By using FLUENT fluid dynamics simulation software tosimulate the flow field inside the flotation cell from the perspective ofturbulence and gas-liquid, this study explains the effects of impeller speed andaeration rate on flotation behavior.By the use of laboratory-made inflatable flotation machine, this researchdid the unit laboratory flotation experiment and discussed the effects of impeller speed and aeration rate on wide grain size coal floatation. Experimentresults showed that the aeration rate was400L/h and the impeller speed was1000r/min, and that the coal recovery and the recovery combustion of coal wasable to get the peak. Compared with aeration rate, impeller plays a moreimportant role in floatation.The Narrow grain size of coals fits the primary flotation kinetics model.Impeller speed has a great influence on floatation rate constant k for smallersize and density particles. With the impeller speed increasing, the floatationrate constant increased; but when the impeller speed is too large, the floatationrate constant will decrease. However, high impeller speed will raise thefloatation speed constant of larger and high density particles. Thus impellerspeed is not a good option for coal floatation. Besides, particle size is anotherfactor of floatation speed. As the particle size goes up, the rate constants willbe gradually reduced, which also lower the attached probability.From the results it can be seen that the flotation rate constant k is affectedby coal size, density, and flotation machine impeller speed. This researchanalyzes the experimental data by using mathematical computingsoftware-MATLAB to establish the floatation rate constant k with theimpeller speed, coal density and sizes by multivariate nonlinear model. Also,from the prospective of flow field turbulence of gas-liquid, this researchanalyzed the impeller speed and aeration rate concerning floatation infloatation cell. In this study, the use of fluid dynamics simulation software-FLUENTenables simulation of flotation cell’s flow field, which canbe seen from the simulated figures, excessive rises of aeration rate willincrease the surface turbulence of flotation cell, thus the attached probability ofcoarse particle sizes are likely to decrease. However, with higher impellerspeed, the turbulence in rotor region of flotation cell is significantly enhanced;excessive rises of impeller speed will increase the turbulence in floatation.Thus, appropriate impeller speed will raise the collision probability andattached probability, which will be an advantage for increasing the efficiencyof particulate and bubble mineralizationResearch of kinetics characteristics, coal recovery and the recoverycombustion of coal showed that relatively high rotor velocity (800r/min) withlow air-flow rate (400L/h) was useful for coarse coal flotation, when otherconditions were invariable. The flotation rate constant model was thusestablished, and through this model, some interaction between floatation speedconstant k and impeller speed, density and sizes can be revealed. |
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