computational fluids dynamics

Thickeners are the key units in the hydrometallurgical processing operations and used to separate solids from liquids. In this research, the pattern of mixture of the pulp and clear water phases in a mixing duct known as E-DUC was calculated through CFD, and the effect of flow rate changes and solids content of the input feed on dilution before the feed well was studied. Fluid dynamics were studied by modeling continuity and Navier-Stokes equations in Fluent version 14.5. The k-ε library function was used to apply turbulent flow conditions and the mixture model was used to study multiphase flows. The flow rate and solids content of the feed under the factory’s operational conditions were 605.45 m3/h and 25%, respectively. In this study, dilution of the feed flowing into the feed well was calculated to be 19.51 using simulations under operational conditions, which was an acceptable estimate of the existing dilution. Afterwards, by changing the flow rate of the feed, the effect of this parameter on dilution of the pulp input to the feed well was determined. By increasing the flow rate to 700 m3/h dilution levels rose to 28.5 respectively.

Although cyclones have simple geometries their flow is really complicated. Inlet fluid temperature is one of the factors that increases its complexity. Variation of the thermo-physical properties of the working fluid with temperature causes cyclones to have different pressure drop and particle separation efficiency. In this paper, the effect of fluid and particles temperature on two main performance parameters (pressure drop and separation efficiency) of low-mass-loading Stairmand high efficiency cyclone are numerically investigated. Eulerian-Lagrangian approach is used to model twophase flow. Simulation is performed at a temperature range of 293-700 K and four inlet velocities. Also, the turbulent equations are solved with unsteady Reynolds stress method. Results show that increasing in dynamic viscosity due to increase in fluid temperature, causes increment in shear stress in cyclone body. Therefore, separation efficiency and pressure drop are decreased. If the inlet flow temperature increases by 100 K, pressure drop decreases between 14% and 16% at different inlet velocities. Also, separation efficiency is decreased by 4.64% between the minimum and maximum of inlet temperatures.