Transitional flow behaviour of high concentration mineral slurry

摘要

To enable accurate pump and piping system design to be undertaken for high concentration mineral slurries, the slurry needs to be characterised and the laminar-turbulent transition confidently predicted so to determine the flow regime the designed system will operate in. Direct application of the yield-pseudoplastic model to the pipeloop test work data enables determination of the rheological parameters used in the slurry characterisation allowing the use of the established laminar-turbulent transition prediction methods. This empirical study compares 9 established laminar-turbulent transition prediction methods, based on the modified Reynolds number approach, against 26 observed laminar-turbulent transition velocities using pipeloop test work results of two high concentration mineral slurries; zinc tailings and fly ash. The best performing laminar-turbulent prediction methods for both slurry types were able to accommodate the three rheological parameters; Yield stress, fluid consistency index and flow behaviour index to capture the complexity of these non-Newtonian slurries. Other future work identified during this study include; determining modified Reynolds number slurries actually transition at to challenge transition criteria of Re ~ 2100, the influence of yield stress as more than simply an ordinate off-set in predicting transition, and the phenomenon of the spike in standard deviation of the pressure gradient during transition.