Browsing by Author "Jokilaakso, Ari, Prof., Aalto University, Department of Chemical and Metallurgical Engineering, Finland."

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CFD modeling of multiphase flows in bottom blown copper smelting furnace
(2023) Song, Kezhou
School of Chemical Engineering | Doctoral dissertation (article-based)
The advancement of copper production techniques has witnessed significant developments, with the continual emergence of new copper smelting and converting equipment and processes. The application of Bottom Blown Copper Smelting (SKS, ShuiKouShan) technology has attracted increasing attention since its introduction into production. To reveal the dynamics of agitation within the bath and optimize the variable parameters, Computational Fluid Dynamics (CFD) simulations were conducted on scaled-down and industrial-scale models of SKS furnaces, with various furnace structures and operating conditions. In this modeling research, the Multi-Fluid Volume of Fraction (Multi-Fluid VOF) model wasemployed for the first time in the simulation of SKS furnaces. The simulated results were in good accordance with experimental water models concerning the gas plume geometrics and surface wave characteristics. The numerical model employed exhibits significant potential for broader applicability, not only within the domain of SKS furnaces but also for similar industrial vessels characterized by comparable geometry and gas flow regimes. The simulation results presented the persistent rotation of gas plumes, accompanied by thepresence of low-velocity regions on the opposite side of the plumes. To enhance agitation within these low-velocity regions and minimize the dead zones, it is favorable to install tuyeres on both sides of the furnace bottom centerline. Subsequent investigations revealed that maintaining a certain range for the difference in tuyere angles between the two rows of tuyeres strikes a balance between the enhancement of agitation performance and the extension of refractory lining lifespan. Apart from tuyere arrangements, tuyere diameter and bath depth emerged as influential factors in bath agitation performance. A relatively reduced tuyere diameter and a deeper bath are suggested to enhance fluid motion within the low-velocity regions, thereby improving mixing behavior. While melt density was observed to exert a relatively modest influence on bath agitation, it was noted that lower melt viscosity contributes to enhanced melt fluidity, improved agitation performance, and a weakened impact on refractory lining. It is noteworthy that copper bottom blown smelting technologies have undergone extensive optimization through resource-intensive onsite experiments, without systematic theoretical guidance. Conclusions derived from the simulation presented in this thesis offer valuable references for industrial practice, presenting diverse fundamental principles governing the bath flow field. Furthermore, the CFD modeling provides the industry with important modeling information, as the furnace structure parameters were selected from a commonly employed range, thereby ensuring the usefulness of the simulation results for broad application in SKS furnaces.