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Hydrocyclone Separator


Hydrocyclone separators are used worldwide in the mining and mineral processing industries for classification, de-sliming and de-watering applications. Their main purpose is to separate a stream of particles into different size fractions. However, they are also effective in applications where a fine slime fraction requires removal or where solids need to be dewatered as much as possible. Hydrocyclones are also used in other industries like manufacturing, food processing, construction (aggregate) and wastewater management.

Multotec’s hydrocyclone separators offer improved efficiency, increased longevity and reduced energy requirements. These inherent values have been gained through optimising our Hydrocyclones over hundreds of plants and jobsites throughout the world, and intensive R&D.

Benefits of Multotec’s range of hydrocyclones include precise cut points in your slurry, improved capacity and reduced wear rates with Multotec’s scrolled evolute design. Some of the product features include:

  • Customisable cyclone sizes & designs customised to application requirements
  • Innovative designs that reduce turbulence & misplacement of product
  • Abrasion & heat resistant liners materials that reduce wear

We manufacture a complete range of off-the-shelf cyclone separators and customised solutions. This ensures that our recommended solution matches your specific process requirements. We also manufacture cyclone distributors that support up to 62 cyclone separators.

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Classification Cyclones

A desanding hydrocyclone is used in the aggregate industry.

High-capacity classification cyclones constructed with steel shell, and rubber or ceramic lined to suit your application.

Dense Medium Cyclones

Multotec’s hydrocyclone price is cost competitive.

Provides max. separation efficiency & wear resistance in harsh applications. The ultimate in alumina tiled cyclone design.

Tailings Dam Cyclones

Classification cyclones form part of Multotec’s hydro cyclone range.

Weighing only 45 kg, with a 220 mm ID and 20° cone angle, they are designed for use in tailings dams & tailings management.

Cyclone Distributors

Cyclone distributors for up to 62 sand cyclone separators.

Distributors that accommodate between 2 and 62 cyclones provide a cost-effective, efficient, long-lasting solution.

Cyclone Accessories

Accessories help to achieve cyclone maximum flow rate in the spiral flow.

Ensure hydrocyclone peak performance with ranges of wear liners, rubber linings, spigots, valves, gauge adapters and more.

Cyclone Spares

>  A range of spares that facilitate optimised centrifugal action.

We manufacture spares for every part of our DMS & hydrocyclone ranges, amounting to over 10 000 producible cyclone spares.


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Hydrocyclone separator design

The hydrocyclone separator is simplistic in design that uses pressure created by a centrifugal pump or hydrostatic head to generate centrifugal force and flow patterns within the hydrocyclone. It does not have any moving parts, but consists of an inlet section, vortex finder, cylindrical section, a conical section, an underflow spigot section and an overflow pipe.

While the primary design of the hydrocyclone remains the same regardless of the industry, there are differences in the cyclone’s size and configuration depending on the application requirements.

The combination of centrifugal force and drag force creates separation within a liquid medium which serves as the transport medium. Larger diameter particles separate easier compared to smaller diameter particles. The hydrocyclone is sometimes referred to as a hydrocyclone centrifugal separator due to the centrifugal forces that forms within the unit.

Depending on the industry and application requirements, hydrocyclones are sometimes referred to as a hydro cyclones sand separator and, in the construction aggregate industry a desliming hydrocyclone is a common term.

Where the hydrocyclone is used for dewatering purposes, it can also be called a hydrocyclone separator or hydrocyclone stacker.

Designed for effective separation

For hydrocyclone separation to be effective, the cyclone must be installed vertically, with the sedimentation tank placed directly under the cyclone.

There are however applications where the cyclone can be installed at an angle, but this will be to reach specific objectives like a coarser cut point or more consistent underflow densities.

The conical shape speeds up the velocity of the water, which in turn increases the centrifugal forces which results in maximising separation efficiency.

Multotec developed the scrolled evolute design, which offers much higher capacity when compared to the standard tangential and involute inlet designs.

The unique scrolled evolute design maximises the hydrocyclone separation efficiency while lowering operating costs. Vortex finder wear, a problem experienced on earlier designs, is eliminated with the scrolled evolute inlet design.

We use specialised ceramic liners to protect the outer vortex of the cyclone from excessive wear.

The Multotec hydrocyclone separator range consists of cyclone diameters ranging from 25mm to 1400mm, allowing them to accommodate a range of volumetric flow rates and cut size requirements. Different vortex finders, cone angles and spigot diameters are standard for all diameters.

Hydrocyclones up to 100 mm (small diameter hydrocyclone) are manufactured mainly from polyurethane. Larger cyclone separators can be supplied as steel polyurethane lined units, steel ceramic or silicon carbide lined units or steel rubberlined units where the rubber liners can be either vulcanised or fitted with loose rubber liners.

On what principle does a cyclone separator work?

Cyclone separators work on the principle of inertia to separate matter. Hydrocyclones are specially designed to provide an environment where centrifugal force can be harnessed to separate matter based on size and density.

  • During the separation process, feed slurry enters the top of a cylindrical feed chamber into the cyclone.
  • As the feed enters the chamber, the slurry inside the cyclone begins rotating. This causes centrifugal forces to accelerate the movement of the particles towards the outer wall.
  • The particles then move downward in a spiral pattern through a cylindrical section and into the conical section.
  • The smaller mass particles move toward the centre and spiral upward and out through a vortex finder and is discharged through the overflow pipe.
  • This discharge is called overflow and contains the finer particles and most of the water. It should be discharged at or near atmospheric pressure.
  • The higher mass particles, called underflow, stay in a downward spiral path along the walls of the conical section and slowly exit via the orifice at the cyclone apex or spigot. Underflow should also be discharged at or near atmospheric pressure.

Multotec Cyclones - Tailings Cyclone

Multotec’s CL Cast Iron Cyclones

4Start Thread Cyclone

Sizing your hydrocyclone separator

The point of separation between coarse and fine particles is called the cut point. Several factors must be considered when selecting a cyclone to achieve this cut point. This includes solids feed volumetric flow rates, solids feed concentration, size distribution, the required duty of the hydro cyclone, and expected cut point.

In cyclone selection, considering the optimal hydro cyclone diameter and configuration like the cone angle and vortex finder is important to maximise separation efficiency, minimise operating cost and minimise energy requirements.

Once the hydrocyclone is operational, any significant changes in operating conditions can be accommodated via vortex finder and spigot diameter changes. Seldom will a different cyclone diameter be required.

Multotec will help you to size your separator appropriately or provide a completely customised cyclone solution to optimise your classification efficiency.

Multotec provides full technical support and field service, together with high availability of cyclone spare parts and accessories to help ensure maximum plant performance.

Expertise on your doorstep

Multotec is a world-renowned manufacturer of equipment and solutions for the international mineral processing industry. We have a global presence achieved with branches, distributors and expertise on your doorstep. Multotec is in 100 countries across 6 continents.

We continually develop capacity, skills and infrastructure in our local operations worldwide. We do this as close to our customers’ plants as possible to ensure fast and effective responses to your mineral processing solution needs.

Our strategic stockholding of equipment, comprehensive ranges of spare parts and tailored field services are all designed to help you get more from your ore.

Multotec is world-leader in ore processing equipment.

Frequently asked questions

Why use a hydrocyclone?

Hydrocyclones (or cyclonic separators) effectively and selectively concentrate slurry particles in a process that separates and classifies them. This simple process separates slurry mixtures so that larger particles leave through the hydrocyclone’s underflow. The remaining water and fine particles exit through the overflow.

The classification process can be very efficient in extracting even the finest precious minerals, preventing waste, while the natural force generated by the shape of the cyclone reduces energy consumption. Waste prevention and low energy costs contribute to maximum profitability.

How do hydrocyclones work?

Their cylindrical top and conical base create a vortex, in turn creating a centrifugal force. It is this centrifugal force that separates and classifies the various size particles by forcing lighter particles through the top overflow, with larger solid particles exiting via the bottom underflow.

What components make up a hydro cyclone?

An industrial hydrocyclone has no moving parts and is made up of a vertical cylinder with a conical bottom. The cylinder is closed at the top with only enough space for the vortex finder (liquid overflow pipe) to extend into the cyclone body. The underflow discharges though a spigot or apex and ensures the correct underflow density is maintained.

What is cut size in a hydro cyclone?

In a hydrocyclone, cut size is the separation point between particles deemed to be either ‘coarse’ or ‘fine’. If a particle is at the cut point size, it will have a 50% chance of reporting to either the overflow or underflow.

Any particle size greater than the cut size is deemed a coarse particle and will exit via the underflow. Fine particles – those less than the cut point size – are discharged via the overflow.

What is a vortex finder?

A vortex finder is a small pipe that extends from the overflow discharge section of a hydrocyclone into the body. Its main purpose is to prevent incoming material from short circuiting the classification process, which in turn leads to reduced separation efficiencies.

By changing the vortex finder diameter, the cyclone cut point can be altered as well as the capacity of the cyclone or operating pressure.

Who invented the cyclone separator?

Initially called a cyclonic separator, it was patented in 1885 by the American, John Finch. Designed as a cyclone dust collector, the technology found a wider industrial appeal by offering large scale separation in factories or mills during the 1900s.

Do you have questions for our cyclone division? Contact us here.

International mining houses such as Glencore Xstrata, Anglo Coal and BHP Billiton use Multotec’s equipment to reduce running costs and optimise plant performance.
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