3. Experimental
The laboratory scale Reflux Flotation Cell used in this investigation
is shown schematically in Fig. 1. It featured seven 1 mlong and
0.7 mm thick stainless steel plates set at an angle of inclination of
70 with respect to the horizontal, creating eight evenly spaced
channels with a perpendicular gap of 9.3 mm. The vertical
chamber, above the inclined channels, was 1 m in length, with a
cross-sectional area of 72 cm2, excluding the area of the downcomer.
All fluxes reported are based on this area. At the top of the vessel
a truncated rectangular pyramid formed a plenum chamber for
fluidization water to enter the cell though a grid of 1.5 mm
diameter holes via a four-way manifold. Located centrally to the
fluidization distributor was the product discharge port, with the
downcomer passing through the middle. Thus the overflow rose
up through an annulus surrounding the downcomer before exiting
through a discharge port. The sleeve and sparger downcomer,
300 mm long and 25.4 mm outer diameter, had a media grade of
10. A further 230 mm length of smooth, non-porous tube, sealed
at both ends, was connected to the base of the sparger to form a
530 mm long, high shear mixing zone consisting of a 4.8 mm
annulus gap. The outlet of the downcomer was located 0.33 m
above the entrance of the inclined channels.