The Vertical Froth Pumps is specifically designed to solve pumping difficulties seen with froth or a high-viscosity slurry.
Froth pumps are vertical shaft slurry pumps with integral sumps generally used on the output from froth flotation cells. Centrifugal pumps cannot pump froths, and therefore require sufficient volume in the sump to hold the froth until broken down to a liquid. The froth is broken down by being sheared in the sump either by reverse swirl spirals at the entrance to the pump, or by mechanical agitators on the pump shaft, or by use of water sprays. To provide enough volume within the sump for froth retention, a froth application factor is applied for pump sizing. This factor is higher the more stable the froth and is multiplied by the flow rate to size the unit. However, power is calculated from the liquid flow rate. Froth factors can generally be estimated only from experience with the slurry and must be supplied by the user.
Froth pumps have been used as general slurry pumps that are self-regulating, in that when the sump empties, the pump partially air locks until the level in the sump rises again. The cantilevered shaft design limits the head that can be generated.