A centrifugal extractor mixes the phases in a rotating drum and then separates them under centrifugal force thousands of times stronger than gravity. Residence time falls from minutes in a gravity settler to seconds, and the machine is compact and sealed. Throughput is set by the drum geometry and rotational speed, and stage count by arranging units in series.
Why it matters in practice
Short residence time matters twice: for fast-degrading or radioactively hot systems, and for crud-prone feeds where solids have little time to stabilise the interface. The trade-off is that solids still have to go somewhere, and disc-stack internals themselves foul, so centrifuges complement rather than replace gravity settlers.
How it is measured or specified
Specified by throughput per unit, 1 to 10 m³/h depending on drum size, drum speed of 3,000 to 5,000 rpm, and the phase ratio it can hold without losing the interface. Residence time in the mixing zone is 5 to 30 seconds, so mass transfer must be fast enough to complete in that window, which is confirmed in a batch shake test before a unit is sized. Solids tolerance is the practical limit, typically below 100 ppm, because the internals foul where a gravity settler would simply accumulate crud.
Equipment referenced in this entry
Related terms
Where this appears on this site
Reference entry GL-CENTRIFUGAL-EXTRACTOR. Source slug centrifugal-extractor · segment liquid-liquid-separation. Definitions on this page describe engineering practice in hydrometallurgical process design; they are not a substitute for test work on your own material.
Working with Centrifugal Extractor? Send the feed material, the throughput and the medium — an engineer replies with a preliminary configuration and the sizing reasoning attached.