Decanter Centrifuges

Decanter centrifuges : Principles of operation.

The fundamental principle of a decanter centrifuge is accelerated sedimentation under gravity.

The sketch (a) below shows a simple settling tank with a continuously moving scraper removing the settled solids at the left hand end. The liquid flows over the top of the scraper blades and leaves the tank at the right hand end. According to Stoke's Law a solid particle within the tank will settle at a rate dependant on a variety of factors including the relative  density of the solids and the liquid, the size of the particle and the acceleration due to gravity.

If the tank is transformed, as shown in (b), into a tapered cylinder (c) and the cylinder is then rotated at high speed about its centre line a high centrifugal 'G' force is produced on the liquid and solids. This centrifugal 'G' replaces the acceleration due to gravity in Stoke's Law and results in rapid sedimentation of those particles that are denser than the liquid. The continuously moving scraper in (a) is replaced by the helix shown in (c) which transports the solids out of the tapered end of the cylinder allowing continuous separation. The original settling tank (a) has now been transformed into a decanting centrifuge (c).

There are many variations of decanting centrifuges in use  in a wide variety of process applications; however the  basic principles outlined above apply to all types of  decanter centrifuge

Broadbent decanter centrifuge designs provide :

• Capacities up to 200 CuM / hour feed.
• Proven heavy duty reliable designs.
• Continuous operation with minimum supervision.
• Fully sealed or pressure tight options available for use of hazardous chemicals.
• Fully wear protected for use on abrasive mineral duties.
• Available in a wide range of materials of construction.