The Froth Pump is specifically designed to solve pumping difficulties seen with froth or a high-viscosity slurry.
Forth pump is a vertical shaft mud pump with an integral tank typically used for the output of a froth flotation cell. Centrifugal pumps cannot pump foam, so there is a need to have enough volume in the sump to hold the foam until it breaks into a liquid. The foam is sheared in the foam tank by a reverse vortex helix at the pump inlet, or by a mechanical agitator on the pump shaft, or by using water spray. In order to provide sufficient volume in the oil sump to retain the foam, a foam application factor is applied to sizing the pump. The higher the factor, the more stable the bubble and multiply by the flow rate to determine the size of the unit. However, the power is calculated based on the liquid flow rate. Foam factors are usually only estimated based on the experience of the slurry and must be provided by the user.
Forth pumps have been used as self-regulating general slurry pumps because when the forth pump is emptied, the pump is partially airlocked until the liquid level in the sump rises again. The cantilever shaft design limits the head that can be produced.