Comparison of two-way coupling models for confined turbulent gas–particle jets in flash smelting

Abstract

Flow predictions of confined particle-laden gas jets based on three different two-way coupling models of gas–particle turbulent interaction are compared for 50 and 200 μm particles at inlet particle/gas mass fractions from about 0.3–3.0. Attention is focused on the application to fluid dynamic models of flash smelting. Two confined jet experiments and a flash furnace double-entry jet are simulated. Three types of inlet flow are represented: (1) dominant primary (central) velocity; (2) primary and secondary velocities of similar strength; and (3) dominant secondary stream. Flow type 1 is conceptually similar to flow in a single entry flash furnace shaft, and type 3 is typical of a double-entry flash furnace shaft. All two-way coupling models were acceptable to a varying extent when compared with experimental data at low particle concentration for the dominant primary jet. However, differences increased with increasing particle loading, but were very much smaller for 200 μm particles than for 50 μm particles. Significantly, very large differences between the predictions were obtained for the flash furnace jet with the dominant secondary flow. The results highlight the need for more experimental velocity data at an elevated mass fraction and for type 3 flows. It is suggested that preferential concentration of particles will occur when the secondary inlet stream dominates and will consequently limit the validity of conventional two-way coupling models in double-entry flash furnace models.