Study On Three Phases Flow Characteristics In The Processing Of Flotation

Pneumatic-mechanical flotation machine is widely used in mineral processing of flotation. However the multiphase flow characteristics of flotation is complex. The characteristics of flow field in pneumatic-mechanical flotation machine designed are systematically simulated based on CFX software.The liquid simulation results of standard k-ε turbulence model show that velocity,turbulence and viscosity intensity are higher in rotation region. With the radial distance increasing, velocity reduces gradually in range of 60~110mm. In the range of350~500rpm, the velocity, eddy viscosity intensity, impeller and stator surface pressure are proportional to the impeller rotation speed.The mathematics model of dispersed solid and gas by adopting k-ε equation for liquid and zero equation for dispersed phases is established for two-phase simulation. The simulation results of solid-liquid two-phase indicate that as the particle size increases, the fluid velocity decreases, surface pressure of the impeller and stator gradually increase in range of 50~120μm. Density has a little effect on flow characteristics which is lower than5.0×103kg/m3. And high viscosity mineral particles have a poor flotation efficiency.Simulation results of gas-liquid multiphase indicate that surface tension and drag coefficient have a little effect. And the grace drag with surface tension coefficient of0.073 for interphase force model is determined. The gas phase velocity and eddy viscosity intensity distribution are not uniform resulting in the worse separation efficiency as the gas inlet speed exceeding 2.0m/s.The Schiller Naumann drag with turbulent dissipation of favre averaged drag force model for the solid-liquid fluid pair and the grace drag with turbulent dissipation of Lopez de Bertodano model for gas-liquid fluid pair are determined. Sato enhance eddy viscosity turbulence conversion model is adopted for three-phase flow simulation of flotation. And the flow characteristics of flotation machine is systematically simulated.