Types of Magnetic Separators and How to Choose the Right One

Magnetic separators are not interchangeable. A wet drum separator designed to recover magnetite from slurry cannot perform the same duty as an overband magnet removing steel from a conveyor, while a standard low-intensity drum may be ineffective for weakly magnetic minerals such as hematite.

The correct magnetic separator depends on four basic questions:

1. Are you recovering a valuable mineral or removing unwanted metal?

2. Is the feed dry, wet or carried on a conveyor?

3. Is the target material strongly magnetic, weakly magnetic or non-ferrous?

4. What are the particle size, throughput and required product quality?

This guide compares the main types of magnetic separators, their suitable applications, limitations and selection criteria.

Magnetic Separator Types at a Glance

This table is a starting point only. Representative material testing is still required for mineral-beneficiation duties.

How Magnetic Separators Are Classified

Magnetic separators can be classified in several different ways.

By Feed Condition

• Dry magnetic separators process free-flowing solids without adding water.

• Wet magnetic separators process particles suspended in slurry.

• Conveyor-mounted separators remove metal from bulk material in motion.

By Magnetic Intensity

• Low-intensity magnetic separators generally recover strongly magnetic materials.

• High-intensity separators target materials with weaker magnetic susceptibility.

• High-gradient separators concentrate magnetic force around a matrix or specially shaped surface.

Field intensity alone does not define performance. Magnetic-field gradient, working distance and magnetic circuit design are also important.

By Magnetic Source

• Permanent magnetic separators use ferrite or rare-earth permanent magnets.

• Electromagnetic separators create a field using energized coils.

Permanent magnets do not consume electricity to generate the magnetic field, although drives, feeders and cleaning belts still require power. Electromagnetic systems can offer adjustable or high magnetic force but normally require more electrical and cooling infrastructure.

By Separation Objective

• Recovery separators collect a valuable magnetic product.

• Purification separators remove small magnetic contaminants.

• Protection magnets remove tramp iron before crushers, mills or conveyors.

• Non-ferrous separators recover metals such as aluminum using induced eddy currents.

These objectives require different machine designs and should not be combined under a single specification.

1. Wet Drum Magnetic Separator

A wet drum magnetic separator processes mineral slurry using a rotating non-magnetic drum and a stationary internal magnetic system.

Strongly magnetic particles are attracted toward the drum shell and transported out of the main slurry flow. Particles with insufficient magnetic response leave through the non-magnetic discharge.

Best suited for

• Magnetite beneficiation.

• Recovery of magnetite or ferrosilicon in dense-media circuits.

• Roughing, cleaning or scavenging of strongly magnetic particles.

• Removal of strongly magnetic contamination from suitable slurries.

Advantages

• Continuous operation.

• Suitable for material already processed in a wet circuit.

• Relatively simple mechanical structure.

• No electrical power required to generate the field in permanent-magnet models.

• Can be arranged in multiple stages.

Limitations

• Conventional models are mainly intended for strongly magnetic material.

• Performance depends on mineral liberation and slurry stability.

• Very fine slimes can be difficult to recover.

• Weakly magnetic ores may require WHIMS or HGMS.

• Downstream dewatering is normally required.

The XINGAONAI Wet Drum Magnetic Separator is intended for wet separation of suitable strongly magnetic materials. Model selection should be based on material testing and actual feed conditions.

For operating details, see Wet Drum Magnetic Separator: Working Principle, Applications and Selection.

2. Dry Drum Magnetic Separator

A dry drum separator uses a rotating shell around a stationary magnetic system.

Dry feed is distributed onto the drum. Magnetic particles remain attached for a longer portion of the rotation, while non-magnetic particles leave the drum under gravity. A splitter divides the two trajectories.

Best suited for

• Dry pre-concentration.

• Recovery of ferromagnetic particles.

• Treatment of dry magnetite-bearing material.

• Iron removal from certain granular materials.

• Recycling and slag-processing applications.

Advantages

• No process water required.

• Continuous operation.

• Relatively high throughput.

• Simple integration into dry processing lines.

• Separate magnetic and non-magnetic discharge streams.

Limitations

• Feed must remain free-flowing.

• Moisture can cause agglomeration and poor distribution.

• Dust control may be required.

• Very fine particles may adhere to other material.

• Feed preparation and close size control may be necessary.

A dry drum should not be chosen simply because the mine is in a dry region. The required liberation size and downstream process must also be considered.

3. Suspended and Overband Magnetic Separators

A suspended magnetic separator is installed above a conveyor to remove tramp iron from bulk material.

An overband separator normally includes a continuously moving self-cleaning belt. Captured ferrous objects are carried away from the conveyor and discharged automatically.

Installation arrangements

• Cross-belt: the cleaning belt runs across the main conveyor.

• Inline: the separator is positioned in line with the main conveyor, commonly near a discharge pulley.

• Manual-cleaning suspended magnet: the captured metal is removed periodically rather than by a continuous belt.

Cross-belt and overband should not be treated as completely unrelated separator categories. A cross-belt unit is commonly one configuration of a self-cleaning suspended or overband separator.

Best suited for

• Protecting crushers and mills.

• Removing steel bars, bolts and equipment fragments.

• Aggregate and quarry plants.

• Coal-handling systems.

• Recycling facilities.

• Cement and bulk-material plants.

Advantages

• Continuous removal with self-cleaning designs.

• Can be added to an existing conveyor.

• Protects valuable downstream equipment.

• Does not require the entire product stream to pass through a drum or matrix.

Limitations

• Capture force decreases as suspension height increases.

• Ferrous objects buried in a thick burden are harder to lift.

• High belt speed reduces exposure time.

• Not designed to recover finely disseminated magnetic minerals.

• The unit must cover the effective conveyor width.

Read Overband Magnetic Separator: Working Principle, Types and Selection for installation and sizing guidance.

4. Magnetic Head Pulley

A magnetic head pulley replaces the normal drive or discharge pulley at the end of a conveyor.

When material reaches the discharge point:

• Non-magnetic particles leave the belt along their normal trajectory.

• Ferrous particles remain attracted to the belt around the pulley.

• They travel farther beneath the conveyor.

• They drop into a separate chute after leaving the magnetic field.

Best suited for

• Continuous ferrous removal.

• Aggregate-processing plants.

• Recycling lines.

• Slag treatment.

• Secondary separation after an overband magnet.

• Applications with limited installation space.

Advantages

• Compact design.

• Automatic continuous operation.

• Uses the existing conveyor trajectory.

• Exposes material as it opens during discharge.

• Can recover smaller ferrous particles missed by a suspended magnet.

Limitations

• Requires modification of the conveyor head.

• Splitter adjustment is important.

• Performance falls when magnetic material is locked inside large particles.

• May not remove large tramp iron early enough to protect upstream equipment.

A head pulley and an overband separator can be used together when both equipment protection and improved ferrous recovery are required.

5. Magnetic Plate, Grate and Drawer Separators

Plate magnets and grate magnets are installed in chutes, hoppers, ducts or gravity-fed process lines.

Material passes over or between magnetic surfaces. Small ferrous particles are captured while the main product continues through the system.

Magnetic plate

A plate magnet is installed against a chute wall or beneath a flowing material stream.

It is typically used for:

• Free-flowing powders.

• Granular material.

• Ceramic raw materials.

• Chemical products.

• Selected food and industrial applications.

Magnetic grate

A grate consists of several magnetic tubes arranged across the material flow.

It increases contact between the feed and magnetic surfaces and can capture smaller ferrous contamination.

Drawer magnet

A drawer magnet places magnetic grids inside a removable housing. Manual or automated cleaning mechanisms remove accumulated metal.

Advantages

• Simple construction.

• No moving parts in basic designs.

• Suitable for small ferrous contaminants.

• Compact installation.

• Useful for product purification.

Limitations

• Accumulated metal can shield the magnetic surface.

• Manual-cleaning units require production interruptions.

• Sticky products may bridge around the tubes.

• They are not normally used for high-capacity mineral beneficiation.

6. Wet High-Intensity Magnetic Separator

A wet high-intensity magnetic separator, or WHIMS, processes slurry through a strongly magnetized matrix.

The matrix creates concentrated magnetic-field gradients. Weakly magnetic particles are captured on or near the matrix, while non-magnetic particles pass through.

During the cleaning stage, the magnetic field is reduced or the matrix moves out of the active field, allowing the captured material to be flushed away.

Best suited for

Subject to testing, WHIMS may be considered for:

• Hematite.

• Ilmenite.

• Manganese minerals.

• Weakly magnetic iron minerals.

• Purification of certain non-metallic minerals.

• Fine mineral-processing feeds.

Advantages

• Can recover material that low-intensity drums cannot capture.

• Suitable for wet fine-particle processing.

• Matrix design produces a high magnetic gradient.

• Operating conditions can be adjusted for different duties.

Limitations

• Higher capital cost.

• Greater electrical and water requirements.

• Matrix blockage can occur.

• Feed preparation must be carefully controlled.

• Clay and excessive slimes may reduce performance.

• Operation and maintenance are more complex.

WHIMS selection should be based on laboratory testing, not mineral name alone.

7. High-Gradient Magnetic Separator

A high-gradient magnetic separator, or HGMS, uses a magnetized matrix containing fine wires, mesh, expanded metal or another high-surface-area medium.

The matrix creates localized areas with steep magnetic gradients capable of capturing fine, weakly magnetic particles.

WHIMS and HGMS are related concepts and may overlap. Many wet high-intensity machines use a high-gradient matrix. Therefore, they should not always be presented as entirely separate technologies.

HGMS is often distinguished by its focus on:

• Very fine particles.

• Weak magnetic response.

• High-gradient matrix design.

• Purification rather than only bulk mineral recovery.

Potential applications

• Removal of iron impurities from kaolin.

• Silica-sand purification.

• Fine hematite recovery.

• Treatment of selected industrial minerals.

• Removal of fine magnetic contamination from process liquids.

Limitations

• Fine matrices can block.

• Feed cleanliness and dispersion are important.

• Cleaning cycles may interrupt continuous separation.

• High recovery can be accompanied by lower concentrate grade.

• Test work is required to select the matrix and operating cycle.

8. Induced-Roll and Rare-Earth Roll Separators

Induced-roll and rare-earth roll separators treat dry, closely sized particles.

Induced-roll separator

An electromagnetic circuit magnetizes a roll or pole arrangement. Weakly magnetic particles follow a different trajectory from non-magnetic particles.

Rare-earth roll separator

A high-strength permanent magnetic roll produces an intense surface field and steep gradient. A thin conveyor belt carries material over the roll, where magnetic and non-magnetic particles follow different discharge paths.

Best suited for

• Dry mineral sands.

• Industrial minerals.

• Selected weakly magnetic minerals.

• Removal of iron-bearing impurities.

• Closely sized, free-flowing feed.

Advantages

• Dry processing.

• Suitable for some weakly magnetic materials.

• Adjustable splitter and roll speed.

• Can produce multiple fractions through staged separation.

Limitations

• Feed must be dry.

• Particle-size distribution should be narrow.

• Thin and uniform feeding is essential.

• Capacity may be limited by the required single-particle layer.

• Mineral testing is necessary.

9. Eddy Current Separator

An eddy current separator uses a rapidly changing magnetic field to induce electrical currents in conductive non-ferrous metal particles.

The interaction between the induced current and the magnetic field generates a repulsive force. Conductive metals are projected away from the normal material trajectory.

Best suited for

• Aluminum.

• Copper.

• Brass.

• Selected non-ferrous metal fractions.

• Municipal and industrial waste.

• Shredded electronic waste.

• Glass and plastics recycling.

Advantages

• Recovers valuable non-ferrous metals.

• Continuous dry operation.

• Can be installed in automated recycling lines.

• Produces different trajectories for conductive and non-conductive materials.

Limitations

• It does not replace a ferrous magnetic separator.

• Ferrous metal should normally be removed upstream.

• Very fine particles may be difficult to separate.

• Stainless-steel response depends on grade and physical condition.

• Particle size, shape and conductivity affect performance.

Strictly speaking, an eddy current separator is not a conventional attraction-type magnetic separator. It belongs in this comparison because buyers frequently evaluate it alongside magnetic metal-separation equipment.

Permanent vs Electromagnetic Separators

A permanent magnet is not always weaker than an electromagnet. Performance depends on the magnetic circuit, magnet material, working gap and machine design.

Wet vs Dry Magnetic Separation

Choose wet processing when:

• The upstream process uses wet grinding.

• The feed is already slurry.

• Fine particles need to remain dispersed.

• Dust control is important.

• The downstream circuit includes thickening or filtration.

Choose dry processing when:

• Material is naturally dry and free-flowing.

• Water is limited.

• The objective is dry pre-concentration.

• The feed is relatively coarse.

• Dewatering would add unnecessary cost.

The complete processing route should be evaluated. Read Wet vs Dry Magnetic Separation for a detailed comparison.

How to Choose the Right Magnetic Separator

Step 1: Define the Objective

First determine whether you need to:

• Recover a valuable magnetic mineral.

• Remove tramp iron.

• Purify an industrial mineral.

• Recover dense-medium material.

• Recover non-ferrous metal.

• Protect downstream equipment.

The objective immediately eliminates many unsuitable machines.

Step 2: Identify the Target Material

Determine whether the target is:

• Strongly magnetic.

• Weakly magnetic.

• Ferrous tramp metal.

• Conductive non-ferrous metal.

• Magnetic contamination in a non-magnetic product.

Mineralogical testing is necessary when magnetic susceptibility is uncertain.

Step 3: Determine Whether the Feed Is Wet or Dry

Record:

• Moisture content.

• Slurry concentration.

• Water availability.

• Flow characteristics.

• Tendency to agglomerate.

• Downstream dewatering requirements.

Wet and sticky material should not be sent to a dry separator without checking its flow behaviour.

Step 4: Measure Particle Size and Liberation

Provide:

• Maximum particle size.

• Typical particle size.

• Percentage of fines.

• Mineral liberation size.

• Distribution of the target material.

A separator cannot release magnetic mineral that remains locked inside gangue.

Step 5: Define Capacity Correctly

For dry equipment, provide:

• Tonnes per hour.

• Bulk density.

• Conveyor width.

• Conveyor speed.

• Material-bed depth.

For wet equipment, provide:

• Dry solids per hour.

• Slurry flow rate.

• Solids concentration.

• Slurry density.

• Feed pressure when relevant.

Quoting only tonnes per hour is not sufficient for wet equipment.

Step 6: Set Recovery and Product-Quality Targets

Higher recovery and higher grade may require:

• Multiple separation stages.

• Regrinding.

• Roughing, cleaning and scavenging.

• Different field settings.

• Intermediate classification.

• Controlled washing.

The machine should be selected for the complete process objective rather than maximum field strength.

Step 7: Evaluate the Installation

Check:

• Available space.

• Working height.

• Structural support.

• Access for maintenance.

• Water and power.

• Corrosive or dusty conditions.

• Lifting requirements.

• Product discharge arrangement.

• Existing upstream and downstream equipment.

Step 8: Conduct Separation Testing

Testing should use a representative sample and measure:

• Feed grade.

• Concentrate grade.

• Tailings grade.

• Recovery.

• Mass yield.

• Moisture or slurry conditions.

• Effect of particle size.

• Effect of feed rate.

• Repeatability.

For variable ores, test more than one representative sample.

Quick Selection Matrix

Common Selection Mistakes

Choosing Only by Gauss Value

A high surface-field number does not describe field gradient, working distance or lifting ability. Compare performance under actual operating conditions.

Treating All Iron Minerals as Strongly Magnetic

Magnetite and hematite respond differently. A separator suitable for magnetite may not recover hematite effectively.

Ignoring Mineral Liberation

Magnetic separation cannot produce a clean concentrate when valuable mineral and gangue remain locked together.

Ignoring Material-Bed Depth

An overband magnet may fail to lift metal buried in a thick conveyor burden even when its surface field appears strong.

Using a Dry Separator for Damp Feed

Moisture can cause agglomeration, uneven feeding and mechanical entrainment.

Selecting Equipment Without Test Work

Published capacity and field strength cannot predict the result for every ore. Representative tests reduce selection risk.

Expecting One Stage to Produce the Final Product

Some applications require roughing, cleaning and scavenging stages to balance recovery and grade.

Conclusion

Different magnetic separator types solve different processing problems.

Wet and dry drums are commonly used for magnetic-mineral recovery. Overband magnets and magnetic pulleys remove tramp iron from conveyors. Plates and grates purify dry products. WHIMS and HGMS process selected weakly magnetic minerals, while eddy current separators recover conductive non-ferrous metals.

The correct choice should be based on the separation objective, material magnetism, particle size, liberation, feed condition, capacity and required product quality. Representative testing is especially important for mineral processing because field strength alone cannot predict recovery or concentrate grade.