Study On Prediction Of Flotation Indexes Based On Fluid Dynamics-Flotation Kinetics Models Coupling

There are complex gas-liquid-solid three phase flows inside the flotation equipment,and the characteristics of the multiphase flow field will directly affect the separation effect of the flotation equipment.However,it is difficult to obtain the characteristics of multi-phase flow through experimental methods.Computation Fluid Dynamics(CFD)technology has been widely used in the study of flow field of flotation equipment as an efficient method to study flow field information.The flotation kinetics models coupled with computational fluid dynamics software can realize the prediction of equipment separation index.However,the existing flotation kinetics models have various forms and their prediction results are also different.Therefore,it is of great significance to study the relationship between different flotation dynamic models and the prediction effect of separation indexes for the development of flotation equipment and the optimization of flotation process by using computational fluid dynamics software.In this thesis,chalcopyrite pure mineral flotation experiments were carried out,and the effects of different flotation kinetics models(collision probability,adhesion probability and desorption probability)on the accuracy of flotation indexes prediction were studied by numerical simulation.The results are as follows:Reliability verification of fluid dynamics-flotation kinetics coupling calculation method.The flotation experiments of chalcopyrite with pulp flow rates of 0.4m3/ h and0.5 m3/h and median particle size of 45μm were carried out on the laboratory flotation column.The experimental flotation rate constants are 0.00391 and 0.00526 respectively.The particle transport equation,Yoon-Luttrell collision probability model,Yoon Luttrel adhesion probability model and Schluze detachment probability model and so on,in the form of user-defined function(UDF)in computational fluid dynamics software FLUENT,coupled with fluid dynamics model is realized.Then,the flotation index was calculated while the flow field information of flotation equipment was solved.The calculated flotation recovery was 0.00316 and 0.00434,and the errors was 19.18%and 17.95%.It provides a method basis for the accuracy evaluation of subsequent flotation kinetics model prediction.Evaluation of prediction accuracy of flotation dynamics model.The collision probability of Yoon-Luttrell,Weber-Paddock,Gaudin and Dobby-Finch,the adhesion probability of Yoon-Luttrell,Dobby-Finch and Min-Nguyen,and the detachment probability of Schluze,Min-Nguyen and Wang are respectively used to form different flotation kinetics models.These models were used to carry out numerical simulation of the flotation condition with pulp volume flow of 0.4m3/h.It is found that the combination of Yoon-Luttrell collision probability,Yoon-Luttrell adhesion probability and Schulze detachment probability is close to and better than the combination of Weber-Paddock collision probability,Yoon-Luttrell adhesion probability and Schulze detachment probability.The prediction errors of flotation rate constants were 19.18%and 19.95%,respectively.Finally,in order to further improve the prediction accuracy of the above two flotation kinetics models for the mineralized tube separation index.The influence of Liepe bubble slip velocity model and its modification model on the prediction accuracy of separation effect was studied.It is found that the accuracy of flotation index prediction does not improve significantly for weber-Paddock collision probability,Yoon-Luttrell adhesion probability and Schulze detachment probability model combination.For the model combination of Yoon-Luttrell collision probability,YoonLuttrell adhesion probability and Schulze detachment probability,Kostoglou’s modified bubble slip velocity model significantly improves the accuracy of flotation index prediction,and the prediction error of flotation rate constant was reduced by 10.74%.