CFD Modelling of matte droplets coalescence in Flash smelting settler

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Insinööritieteiden korkeakoulu | Master's thesis
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Master's Programme in Mechanical Engineering (MEC)
Computer simulations are popular due to difficulty in setup of conventional experimental methods at high temperature processes. Computational Fluid dynamics is an important tool to study settling mechanism in Outotec's flash smelting settler. Commercial Ansys Fluent model was used to study settling previously by researchers, but no study was done to model coalescence. The thesis aims in studying the suitability of the Ansys fluent built in code to model coalescence for flash smelting settler. The success of the model helps to understand copper loss mechanisms and find ways to increase copper recovery. Firstly, collision theory and coalescence mechanism is reviewed thoroughly. Secondly, Ansys fluent built in models for modeling coalescence are listed and compared to select best mathematical model. The primary criteria for selection was ability to model collisions, coalescence, particle tracking and better visualization capacities. The selected discrete phase model is parametrized to model coalescence during settling of matte droplets through slag phase. It is noted that DPM could be used to simulate settling and coalescence of matte droplets. DPM can be used to get the idea of the process/coalescence phenomenon in a short period. The simulation showed droplets change trajectory after collisions/coalescence. Simulation also revealed coalescence dramatically affects settling time. Settling time is not only affected by increase in droplet diameter but also due to change in droplet trajectory after coalescences. However, Parametrized DPM model uses parcels injection technique that makes it difficult to track droplets individually for accurate comparison. In future user defined function should be written to identify and track droplets individually for accurate analysis of individual droplets.
Jokilaakso, Ari
Thesis advisor
Khan, Nadir
Flash smelting, copper loss, coalescence, discrete phase modelling(DPM), Ansys fluent, O’Rourke’s algorithm
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