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 Heavy Media
Heavy Media Hydrocyclones
Basically, heavy media hydrocyclones look like classifying hydrocyclones but they are instead used to clean coal. A gravimetric separation takes place due to the buoyancy effect of the media forcing the lighter coal solids to the center of the hydrocyclone where they are transported upward and through the vortex finder. The dense mineral matter spirals toward the apex and exits through that orifice.
- The heavy media hydrocyclone used in the coal industry is an extremely efficient cleaning device using finely ground (-325 mesh) magnetite and water as the "media".
- The media density primarily determines separating gravity. A relatively wide range of coal sizes can be cleaned in a wide range of hydrocyclone sizes.
- Ceramic lining is critical since high ash "refuse" is very abrasive.
- Pressure should be kept low to mitigate classification of magnetite particles.
- Heavy Media Cyclones are usually operated in a near-horizontal orientation allowing for large apex sizes to be used for refuse removal.
- The only disadvantages, when compared to water-only hydrocyclones, are the associated capital and operating costs of a media recovery circuit (drain & rinse screens, magnetic separators, etc.)
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