review of mixer-settler types and other possible contactors for ...

ALTA Free Paper
Figure 14: Cut-Away Schematic of a Podbielniak Centrifugal Contactor
Figure 15: SX Circuit with Podbielniaks on Extraction and Stripping Duties.
Advantages include:
Can operate with small droplets promoting rapid kinetics.
Less back mixing than columns.
Can operate with liquids with small density differences.
Because of the very short contact time, it can handle relatively high flow rates, up to 140 m3/h of
feed solution. Capacity is proportional to speed of rotation.
Can operate with either phase continuous over a wide range of phase ratios.
Has a very low organic inventory – typically about a factor of 25 times less than an equivalent
mixer-settler circuit.
Very small footprint area and is totally enclosed (has balanced mechanical seals).
Flexibility can be provided through changing feed location, seal arrangement and internal
elements.
Disadvantages include:
No access or viewing of process while in operation. (Access is provided for inspection and
cleaning).
Tend to be expensive, but this is offset by low organic inventory, low footprint area, and less
structures.
Limited tolerance to suspended solids.
Power requirement.
More sophisticated operation and maintenance than mixer-settlers.
19