Flow of Concentrated Fine Particulate Slurries through Complex Geometries

Publication Reference: 
Author Last Name: 
Prof Raffi M. Turian
Report Type: 
FRR - Final Report
Research Area: 
Wet Systems
Publication Year: 
Publication Month: 
United States


The characterization, stability, rheology and flow of titanium dioxide, laterite, gypsum and silica flour suspensions have been studied. The flow experiments included the determination of the pressure drops for suspension flow in straight pipes, bends, fittings, valves and Venturi meters. The shear stress/shear rate/concentration dependence for the suspensions was determined using a capillary rheometer and rotational viscometer. This dependence was correlated using the Sisko model, which was then used as the basis of the friction factor/Reynolds number correlations for suspension flow through straight pipe in the laminar and turbulent regions, and for prediction of laminar-turbulent transition. The resistance coefficients for flow through bends, valves and sudden contraction and enlargement were found to vary inversely with the modified Reynolds number (based on the power-law parameter) for laminar flow, and to approach constant asymptotic values in turbulent flow. The results pertaining to the lami lami nar and turbulent regions can be used for design purposes. For the Venturi meters it was found that at high flow rates the discharge coefficients based on calibration using single phase flow are applicable to suspensions. The yield stresses of the suspensions were measured directly using the vane method. An empirical equation was used to correlate theyield theyield stress/concentration dependence, This equation provides a quantitative means for assessing the low and high concentration yielding behavior of the suspensions. The maximum packing solids volume fraction was used to provide a link between the stability and rheology. The results of the sedimentation, the yield stress measurements, and the Sisko model parameters were found to follow consistent trends. The data for our gyspum suspensions were used to compare the straight pipe-flow friction loss correlations established in this part using the rheologically-based, continuum approach with those using the multiphase flow aproach based upon solutions of the equations of continuity and motion. It was found that both methods do an excellent job job in the case of gypsum whose particle size overlaps the colloidal and noncolloidal ranges.