| Abstract: | This paper reviews the development of a new annular shear cell for the characterisation of aerated powders. The cell enables the measurement of the transmitted shear stress at degrees of aeration below fluidisation. Results are presented for three powders, Alumina, Phosphate Rock and Sodium Carbonate. These show a large reduction in shear stress for small quantities of air entrainment and a transition from normal coulomb-solid flow to liquid-type flow at high shear rates. This characterisation enables an explanation of the flooding phenomena experienced in powder handling processes. |
