Abstract:
The current work investigates the transportation of bauxite slurry through rheology as well as experimental pilot plant studies in horizontal pipelines. The work utilizes the sample prepared at a median particle size (d50) of 23.3 mu m, followed by its characterization including temperature-dependent rheology to understand the flow behavior. The tests performed through 50 mm and 100 mm NPS (nominal pipe size) loops on three solids concentrations, 35.2%, 40%, and 45.3% by weight, showed non-Newtonian pseudoplastic behavior with yield stress. The slurry showed a good fit to the Herschel-Bulkley (H-B) model in the tested concentrations. The effect of solids concentration and nominal pipe size on the pressure drop were studied at an operating velocity range of 0.57-1.86 m/s. The semiempirical H-B models developed by Torrance, Wilson and Thomas (W&T), Slatter, Chilton and Stainsby (C&S), along with extended modifications to Tomita and Dodge and Metzner (D&M) models were used to estimate the pressure drop and transition from laminar to turbulent flow regime. The W&T model showed minimum NRMSE (normalized root mean squared error) for all the concentrations in both pipe sizes. The work also estimates the optimum solids concentration for a given throughput of 1,500 tons per hour (TPH) based on the W&T model. Finally, the challenges faced in determining the critical settling velocity and transition point of flow regime were addressed with possible adaptive methods for further investigation.
