Top Things to Know When Considering a Cyclone Purchase

Cyclones are relatively simple, but there is a lot to understand to get the most out of your investment. When talking about wet processing, two types of cyclones are primarily used – the standard hydrocyclone and the dewatering cyclone. Both types can even be used in the same process plant but with different services. While both have a lot in common, each one also has its own subtle differences.

 Commonalities

• Cylindrical feed chamber with tangential or involute inlet.
• Vortex finder and overflow piping.
• Conically shaped below the feed chamber.
• Discharge apex.
• No moving parts.
• Abrasion-resistant linings; rubber, urethane, or ceramic typically.

Individual Features of Hydrocyclones

• The overflow of a hydrocyclone should be terminated at a 180 degree return with no down-piping below the feed chamber.
• The apex should be unobstructed and sized properly for the amount of material that will report to it.
• Both overflow and underflow (apex) are vented to atmosphere.
• A hydrocyclone will make a volumetric split with a certain amount of the slurry reporting to the overflow and overflow, depending on the sizing of the vortex finder and apex.

Individual Features of Dewatering Cyclone

• The overflow of a dewatering cyclone should have a down-leg of piping that is sealed to atmosphere at the discharge. This down-leg creates the negative pressure that allows more water to be removed thereby creating a more-dense underflow.
• The apex should also be sealed by means of an underflow regulator. The underflow regulator is basically a check valve that prevents air from being drawn into the cyclone, negating the effect of the down-leg.
• Both overflow and underflow must be sealed to atmosphere.
• The split between the overflow and underflow can be manipulated by means of a vacuum control valve connected to the overflow piping. Bleeding air through the control valve should be the only air introduced into the system.
• With the overflow piping and apex sized properly, a dewatering cyclone can produce a high-density, stackable underflow product with a minimal amount of good material wasted through the overflow.

When do you need a hydrocyclone?

• To make a cleaner, sharper cut.
• High density underflow is not important.
• Tonnage rates vary significantly.
• Remove water volume from slurry to feed another piece of process equipment with low water volume tolerance.

When do you need a dewatering cyclone?

• When sharpness of cut is not important.
• High density underflow is desired.
• Tonnage rates are fairly steady.
• To make another piece of dewatering or process equipment more efficient.

In conclusion, both types of cyclones have the ability to handle large volumes of slurry with a small footprint and classify/dewater the minerals in the slurry. Both types will capture particle sizes finer than any other type of common process equipment when applied properly. Cyclones are produced in different sizes for a reason. Smaller diameter cyclones will make finer cuts, and larger diameter cyclones make coarser cuts. With either, the cyclone flow demands must be satisfied in order for it to produce the desired result. Care must also be taken to marry the cyclone with other properly sized equipment, in particular the pump feeding it and even the sump. Having any part of the system mismatched (undersized or oversized) can produce an undesirable outcome.

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