A preliminary experimental investigation into the air-lift pumping of shear-thinning suspensions

In a recent article⁽¹⁾, it has been postulated that the air-lift principle may be applied to the raising of liquids or suspensions possessing shear-thinning Theological behaviour, in order that significant reductions in power requirement may be made compared with conventional mechanical pumping. Using a 41 mm i.d. riser, an experimental study of the raising of highly flocculated kaolin suspensions, at volumetric concentrations ranging from 8.1 to 18.4%, has confirmed that power savings are possible, provided that the isothermal efficiency of the compressor for air injection is substantially greater than mechanical pump efficiencies. Such power savings appear limited to a range of superficial air velocity in the air-lift riser of 0.25 to 1.25 m.s.^?1, and to suspensions containing a relatively high volumetric fraction of flocculated solids.