Numerical Investigation Of Chemical Reaction In Gas-liquid Two-phase Flow In Metallurgical Reactors

The oxygen-enriched bottom-blown copper smelting(BBS)is an important step in copper pyro-metallurgy,the prospect of which is quite brilliant in industrial application.However there is a lack of theoretic proof.The refining process is a complicated high-temperature physical and chemical process,including gas-liquid two-phase flow,heat and mass transfer,chemical reaction,etc.Thus,a mathematical model is needed for the numerical study on the gas-liquid interaction,diffusion of gas in the liquid and the interactions between the flow pattern and chemical reaction.According to industrial apparatus,a physical model is established for the BBS furnace.The k-ε turbulent model and volume of fluid(VOF)multiphase model are employed to investigate the phase interactions and corrosion effects of melt on refractory;the dispersion,breakage and coalescence of gas bubbles are investigated as well.The species transport equations are employed to describe the chemical reactions in the furnace,hence to study the mass fraction evolution of reactants and products,as well as the phenomenon of heat and mass transfer.The conclusions are as follows:growth,coalescence and breakage occur during the bubbles floating process.It costs 1.2s for the first gas bubble to reach the slag/liquid interface in this model,while the following ones cost less.Finally the floating time fluctuates within a certain range,the average of which is 0.9s or so.In the gas-liquid-slag three phase system,the oxygen bubbles get to the slag layer through the liquid metal after entering the furnace;due to the higher viscosity of slag layer,the motion of bubbles are delayed at the interface;the floating bubbles keep hitting the liquid/slag interface,leading to an opening and closing slag eye.When the gas accelerates from 0.04m/s to 0.08m/s,the slag eye forms at 1.02s instead of 1.25s,and the diameter enlarges from 0.024m to 0.052m.As the gas flow rate increases,a larger shear stress makes slag entrapped in the liquid metal.The simulation results of coupled species transport imply:chemical reactions are rather intense around the oxygen nozzle in the mixture model,while proceed at the top part in the multi-component model.During the process reactors reduce while products increase,indicating the reaction making progress.Furthermore,the pressure fluctuating continuously at the oxygen nozzle leads to the blowback of bubbles.