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Solid-Liquid Separation
Filtration
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Decantation
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SEPARATION PRINCIPLES
CENTRIFUGAL FILTRATION
Centrifugal solid-liquid separation using a perforated basket equipped with a filter cloth or removable filter bag.
During centrifugal filtration, centrifugal force produces pressure that forces the liquid through cake, filter cloth, backing screen, and out the basket perforations. The filter cloth retains the solid particles within the basket.
CENTRIFUGAL DECANTATION
Centrifugal solid-liquid, liquid-liquid, or solid-liquid-liquid separation using a solid bowl. Liquid removal is accomplished using a skimmer or by overflowing the bowl rim.
During centrifugal decantation, centrifugal force is used to accelerate the gravity sedimentation process in which a mixture of phases with different densities is forced to settle. In a solid-liquid decantation application, the solid particles move radially through the liquid and accumulate on the walls of the solid bowl. If two liquids with different densities are present, the less dense liquid migrates toward the bowl's axis of rotation.
Glossary of Terms
- Backing screen: a coarsely woven screen supporting the filter cloth, which facilitates the draining of the mother liquor.
- Basket: perforated rotor used for centrifugal filtration
- Bowl: imperforate rotor used for centrifugal decantation
- Cake: the solid phase produced by filtration or decantation
- Centrate: the liquid phase after separation by filtration
- Clarification: a separation process to recover the liquid phase containing minimum solids content
- Decantate: the liquid phase after separation by decantation
- Feed slurry: solid-liquid mixture fed to the centrifuge
- Filter bag: fabricated to conform to the basket's shape, facilitating the removal of solids from manual discharge basket centrifuges
- Filter cloth: supported by the backing screen, the filter cloth retains the solids and allows the liquid to flow through the basket perforations. The filter cloth is chosen based upon the size of the solid particles, and its compatibility with the process.
- Filtrate: the liquid phase after separation by filtration
- Mother Liquor: the liquid phase of the feed slurry
- Rotor: the rotating part of the centrifuge (bowl or basket)
- Shell: the cylindrical portion of the rotor
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