Simulation Of Fluid Dynamics And Mixing Characteristics Of Solid-Liquid Two-Phase Flow In A Self-Aerated WEMCO Flotation Machine

The distribution of slurry flow field and solid suspension quality in the flotation machine significantly affect the flotation index.In this paper,the solid-liquid two-phase flow field in the Wemco flotation machine was simulated,and the mixing characteristics of the solid-liquid twophase flow in the flotation machine were studied,providing theoretical basis and technical guidance for the large-scale design of self-priming flotation machine.The main results are as follows:(1)The Shear stress Transport(SST)turbulence model and Schiller Naumann resistance model were used to simulate the solid-liquid two-phase flow field in the flotation machine and good results were obtained.With the increase of impeller speed,the circulation structure of solid-liquid two-phase flow field does not change,and the slurry velocity,solid suspension uniformity and power consumption increase.When the rotating speed is 365 rpm zeta value of 0.851,solid phase suspension dispersion is better.The slurry inlet velocity has little influence on the slurry inlet velocity,and the solid suspension dispersion is better when the inlet velocity is 0.09 kg/s.The slurry concentration does not change the upper and lower circulation structure of the flow field and the solid dispersion uniformity decreases first and then increases.(2)The physical properties of solid phase affect the suspension dispersion of solid-liquid two-phase flow.At low impeller speed,solids of low density can achieve better solid suspension and increase linearly with the increase of impeller speed.Solids of high density at low impeller speed tend to deposit in large quantities at the bottom of the tank,resulting in short circuit.The dispersion of solid suspension increases with the increase of impeller rated power.In guarantee the same solid suspension uniformity zeta value is 85%,the power consumption of the impeller with the linear density of solid phase increased.The solid phase with small particle size can be completely suspended and dispersed at low impeller speed.Because the gravity of solids with large particle size will affect the suspension dispersion of solid phase,it can be improved by increasing the impeller speed,but too high impeller speed will exceed the rated power of the flotation machine and increase the power consumption of the flotation machine.The suspension uniformity of the solid phase in the mixed state is far less than that in the presence of a single solid phase,and the suspension dispersion of the solid phase with small particle size is better.(3)The mixing time of reagents in the solid and liquid phase systems in the tank is inconsistent,and the mixing time of reagents in the liquid phase system is longer.Different dosing points have different mixing time.When the slurry is added at the entrance,the mixing time of the whole reagent is shorter and the peak value appears first in the circulation area and mixing area,which is more conducive to the interaction between the reagent and the solid phase.Increasing the impeller speed can reduce the mixing time in the flotation machine,and continuously increasing the impeller speed has little influence on the mixing time to reduce the gradient,indicating that changing the speed under the premise of high impeller speed cannot effectively improve the mixing time between the reagent and pulp.Different densities of solids have different effects on the mixing time of reagents in the system.The distribution of reagents in the flotation machine has no great difference with the increase of solid density,but the system with high solid density will result in less distribution of reagents in the separation area.