Simulation And Multi-objective Evaluation Of H 2 SO 4 -O 2 -copper Anode Mud Three-phase Mixing Process Based On CFD And Grey Theory

Copper anode mud is an important raw material for extracting rare and precious metals because it is rich in valuable elements,such as Cu,Au,Ag,Pt and so on.Vertical kettle pressure acid leaching is an important process for extracting valuable metals from copper anode mud.In the process of stirring and leaching,the complex process of gas-solid?air and anode mud?mixing,solid-liquid?anode and H₂SO₄ solution?mixing,gas-liquid mixing and chemical reaction process are performed in the vertical tank.Since the entire process has been in a high-pressure closed state,it is difficult to observe and define internal mixing conditions.So it is not conducive to optimizing the process parameters to improve the leaching rate.In this paper,the three-phase stirring system of H₂SO₄-O₂-copper anode slime was simulated by Computational Fluid Dynamics?CFD?technology,and Euler-Euler multiphase flow model,Standard k-?model and Multi-Reference Frame?MRF?were used to study different rule of mixing effect under different stirring speeds,sulfuric acid concentration,liquid-solid ratio,and temperature conditions.And these four experiments were taken as the research objects,and the gas hold-up,turbulence kinetic energy,sulfuric acid flow velocity and solid-phase motion velocity were taken as comprehensive evaluation indexes for gray correlation analysis.The influence degree of each factor on the mixing performance were obtained.The conclusions are as follows:?1?The Fluent software was used to simulate the solid-liquid two-phase stirring process in vertical kettle.The diffusion of tracer KCl concentration was characterized by the component transport model and the mixing time was calculated.The reliability of the model is verified by the water model experiment with equal proportion of 10:1.?2?The increase of the stirring speed is beneficial to the formation of a strong circulation vortex flow zone on both sides of the double-layer stirring paddle.promoting the vigorous mixing of the H₂SO₄-O₂-copper anode slime three-phase system in the kettle,making the copper anode slime particles and O₂ bubbles distributed more evenly.The increase of the concentration of H₂SO₄ solution leads to the increase of the viscosity of the solution,the increase of the drag force between liquid and O₂ bubbles,which increase the bubbles residence time and the oxygen gas-holdup in the vertical kettle.?3?Combining orthogonal design experiments,the four conditions?stirring speed,sulfuric acid concentration,liquid-solid ratio and temperature?affecting the gas-liquid-so lid three-phase mixing performance were analyzed by gray correlation analysis.The cro ss-section oxygen content,turbulent kinetic energy,average velocity of sulfuric acid solut ion,and average particle velocity of the solid phase were used as evaluation indicators.It was found that the order of the influence on stirring and mixing was:Stirring speed>Temperature>Sulfuric acid mass fraction>Liquid-solid ratio.