Executive Summary
Prediction, Scale Up Test Methods in Solid/Liquid Separation
Investigators: Professor L.R. White, Dr. K.A. Landman, Advanced Mineral Products Centre, Department of Mathematics, University of Melbourne, PARKVILLE VIC 3052
Overall Project Aims
(a) To refine a rheological model which would enable accurate prediction and scale up of solid-liquid separation in flocculated suspensions.
(b) To devise laboratory test procedures which would determine the parameters of that rheological model for any given solid/liquid system.
(c) To model with this theoretical description, existing separationmethods in commercial use with a view to increasing efficiency and economy.
Progress to Date STAGE ONE AND STAGE TWO
(a) The basic features of the rheological model have been developed viz. the role of compressional yield stress Py(o) and the hindered settling factor r(o) in thickening processes. At this stage, shear stress has not been included in the fundamental model. Initial work on computer simulated separation has commenced.
(b) A laboratory procedure for the measurement of P,(o) has been developed and applied in practical systems e.g. red mud.
(c) Modelling of conventional separation processes using the fundamental model havebeen completed for several systems ,
(i) transient batch settling59
(ii) steady state gravity thickener11
(iii) batch pressure filtration, under both moderate and high pressures14
(d) Development of a steady state laboratory test method for the direct measurement of the hindered settling factor r(o) e.g. red mud. A student with Professor D.V. Boger locally has commenced setting up a pressure cell to undertake the required measurements.
(e) Commenced discussions on analysing Professor R.J. Wakeman’s filtration experimental results in terms of our theoretical models.
(f) Collaboration with Exeter on a new experimental program to measure combined compression and shear effects (a filtration cell with a rotating face).
OBJECTIVES STAGE THREE
(a) Detailed comparison of the experimental data obtained by Professor D.V. Boger locally and by Professor R.J. Wakeman at Exeter with our theoretical models.
(b) Modification of the fundamental rheological model to include shear stress effects.
(c) More sophisticated two dimensional (i.e. non-plug flow) modelling of gravity thickeness with the effect of shear yield stress included.
(d) Development of computer simulation models of separation processes.