• Bunney, Karl
• Botsis, Nicky
• Turner, Nicki

Abstract

Slurry flow properties are critical in plant design and operation. The slurry shear yield stress is defined as the minimum force required to initiate slurry flow and is often used in the mining industry to define slurry characteristics in pumping and mixing, pipeline transport, disposal etc. One of the conventional well-known methods for shear yield stress determination is via a simple vane test. This test may be operator dependent, time-consuming and require large amounts of sample. The development of an alternative, more rapid method for determining the yield stress of a large number of samples of low mass would be advantageous. The compressive yield stress is mostly used in the design and control of solid-liquid separation processes and not in slurry flow characterisation, but plots of compressive yield stress versus pulp density tend to follow the same trend for those of shear yield stress measurements. The compressive yield stress is determined by measuring the equilibrium sediment height after centrifuging a slurry sample at a series of different speeds. Test work was conducted on samples from a calcrete-hosted uranium ore to determine whether the compressive yield stress measurements could be used as an alternative to shear yield stress measurements to obtain a relative indication of sample rheological behaviour. Test results showed good agreement. In terms of the sample mineralogy, quartz and dolomite appeared to have a positive effect on sample rheology while smectite affected sample yield stress deleteriously. The compressive centrifuge test may allow for more rapid yield stress determination on an increased number of smaller sample masses with reduced operator involvement.

Topics

• density
• impedance spectroscopy
• Uranium