Blog Archives - Dings Magnetic Group

How Eddy Current Separators Work

Concentric & Eccentric Eddy Current Separator Designs for Aluminum Recycling

In recycling applications, there are many different types of material that need to be recovered. Magnetic separation equipment is ideal for pulling metals like iron and steel out of mixed material streams. However, non-ferrous metals like copper, aluminum, tin, and brass aren’t inherently magnetic, so normal magnetic separators won’t work. Therefore, an eddy current separator is often the best option to remove and recover these valuable non-ferrous metals. What makes an eddy current separator different from a normal magnet? How do they work? Let’s look into what an eddy current is, how they’re formed and how they’re used for separation.

What are Eddy Currents?

When a changing or moving magnetic field is exposed to a conductive material, the change in magnetic flux creates an electrical current in the conductive material. This is in accordance to Faraday’s law of induction. The current flows in a circular motion around the magnetic field lines. This circular motion is what gives “eddy” currents their name, as they are reminiscent of whirlpools or eddies in water.

These electrical currents, as all electric currents do, create magnetic fields of their own that loop around the flow of electrical current. The magnetic field that is created is in opposition to the change in the magnetic field that created it as it tries to remain in balance as explained by Lenz’s Law. This means that the eddy current creates a magnetic field in the conductive material that has the same pole as the magnet that created it. As we know, two magnetic poles that are the same will repel each other. This property is how non-magnetic, electrically conductive metals can be easily separated from non-conductive materials.

How an Eddy Current Separator Works

The key component of the eddy current separator is the magnetic rotor, which has a series of permanent rare earth magnets mounted on a support plate attached to a shaft. The magnetic rotor is surrounded by a wear shell that supports the conveyor belt. This allows the rotor to spin independently and at a much higher speed than the wear shell and belt around it.

When a piece of non-ferrous metal (such as aluminum) travels along the belt and crosses over the separator’s rotor assembly, the magnets inside the rotor rotate past the aluminum at speeds up to 3000 rpm. Since the rotor is designed with multiple magnets in alternating poles the magnetic field can shift thousands of times per minute. As we discussed earlier, this creates eddy currents in the aluminum which, in turn, creates a magnetic field around the piece of aluminum. The polarity of that magnetic field is the same as the rotating magnet, causing the aluminum to be repelled away from the magnet. This repulsion makes the trajectory of the aluminum greater than that of the nonmetallic material, allowing the two material streams to be separated. An optional splitter is often used at this point to ensure that the that the two material streams are properly separated.

Dings Company Magnetic Group Helps You Find The Right Magnetic Separation Solutions.

Dings Company Magnetic Group engineering and sales staff work together from our Milwaukee, WI factory to provide outstanding customer service from experts in magnetic separation. We listen to our customers to gain an understanding of their needs and apply our experience in their trade to provide magnetic separation equipment that is sized and positioned for the best possible performance in their specific application. Contact Us at mailto:magsales@dingscoor call us at (414)672-7830.

Magnetic Separators for Construction & Demolition Recycling

Portable concrete recycling plant with Severe Duty Self-cleaning magnetic separator

The EPA estimates that 600 million tons of Construction and demolition waste were generated in the United States in 2018, which is more than twice the amount of generated municipal solid waste. Of this 600 million tons, much of it, including concrete, metals, and wood, can be reclaimed, processed and resold. This not only generates income for the recycler but lessens the environmental impact of disposal in landfills and the extracting of new materials. The recycled material is also more cost effective for use in new construction projects. This circular economy can benefit all participants, but only if processed and separated correctly and efficiently. Dings magnetic separation equipment helps accomplish this process.

Eccentric vs. Concentric Eddy Current Separator for Recycling

Eddy current separator installed in recycling plant

Whether it’s mixed stream municipal recycling or construction and demolition waste, there are always valuable materials to be recovered. For non-ferrous metals, such as copper, aluminum and brass, an eddy current separator is the best option. Dings co. Magnetic Group manufactures two different types and three model series of eddy current separators, one eccentric and two concentric. The one that’s best for your application depends on several factors. What type of product stream do you process? How much throughput are you trying to separate? What operational features are most important to you? We’ll look into some of these below.

Eddy Current Separator Operation

The key component of the eddy current separator is the magnetic rotor, which has a series of permanent rare earth magnets mounted on a support plate attached to a shaft. The magnetic rotor is surrounded by a wear shell which supports the conveyor belt. This allows the rotor to spin independently and at a much higher speed than the wear shell and belt around it.

When a piece of non-ferrous metal (such as aluminum) passes over the separator, the magnets inside the rotor rotate past the aluminum at high speed. This forms eddy currents in the aluminum which, in turn, creates a magnetic field around the piece of aluminum. The polarity of that magnetic field is the same as the rotating magnet, causing the aluminum to be repelled away from the magnet. This repulsion makes the trajectory of the aluminum greater than that of the nonmetallic material, allowing the two material streams to be separated. An optional splitter is often used at this point to ensure that the that the two material streams are properly separated.

Eddy Current Separator Models

9100 Concentric Eddy Current Separator

The 9100 model eddy current separator is best suited for fractional sized non-ferrous metal up to aluminum cans in a light to medium volume throughput. The 9100 is used in similar application to the 9900 eccentric eddy current but doesn’t have some of the features unique to the eccentric model. The 9100 however can be up to 25% less expensive as a tradeoff. The 9100 model has a magnetic pulley with a diameter of 7 inches and an internal rotor 6.5 inches across. It is offered in belt widths up to 48 inches.

9500 Concentric Eddy Current Separator

Depth of magnetic field is relative to the size of magnets inside the rotor. For example, the Dings 9500 model concentric eddy current separator has a larger/deeper field than the other eddy current separators Dings makes and is ideal for cans and larger sized non-ferrous in a higher volume throughput. The 9500 is often used in processes like auto shredding. The 9500 model has a magnetic pulley with a diameter of 13 inches with an internal rotor 12 inches across. It is offered in belt widths up to 72 inches.

The Dings concentric design’s magnetic rotor Is protected by a triple layered shell.

Hard ceramic tile outer coating
High temp fiberglass outer shell base
Non-magnetic 304 stainless steel inner shell

Both concentric eddy current models are constructed on a heavy-duty structural steel I-beam frame and support structure. They come standard with oversized, high speed rotor bearings and shaft as well as a heavy-duty drive package. The belt is made of wear-resistant Polyurethane or nitrile material.

9900 Eccentric Eddy Current Separator

The 9900 eccentric eddy current separators’ magnetic field is the same as the 9100 concentric version and is ideal for the same types of applications. However, it’s off center “eccentric” magnet design of the rotor allows ferrous metal that made it past the upstream magnetic separator to be released from the belt as it leaves the magnetic area of the outer rotor shell. This reduces the likelihood that ferrous metal will cling to and damage the belt and shell, extending rotor life. Dings eccentric rotor is further protected by a dual layer shell design.

The Dings eccentric design’s magnetic rotor shell.

High temp filament wound outer shell
Non-magnetic 304 stainless steel inner shell

Dings eccentric eddy current separators are constructed on a cantilevered frame with easy to remove supports. The 9900’s built in easy to remove panels give access to bearings and belt. These design features allow the belt to be replaced in less than 15 minutes, shortening maintenance downtime. The 9900 eccentric eddy current model comes with a wear-resistant, endless polyurethane belt with corrugated side walls for material containment. Like the concentric model, the 9900 comes standard with oversized, high speed rotor bearings & shaft. The eccentric eddy current separator has a magnetic pulley with a diameter of 16 inches with an internal rotor 8 inches across. It is offered in belt widths up of 36, 48, or 60 inches.

Dings Company Magnetic Group Helps You Find The Right Magnetic Separation Solutions.

Dings Company Magnetic Group engineering and sales staff work together from our Milwaukee, WI factory to provide outstanding customer service from experts in magnetic separation. We listen to our customers to gain an understanding of their needs and apply our experience in their trade to provide magnetic separation equipment that is sized and positioned for the best possible performance in their specific application. Contact Us at magsales@dingscom or call us at (414)672-7830.

Magnetic Separation for Grain & Bulk Powders

Granular Products That Require Magnetic Separation

For grain, spices, bulk powders, and other granular products the need for metal separation comes down to two factors. First, increasing the purity levels of your product. Second, protecting valuable processing equipment from damage caused by hard ferrous impurities.

As for the type of magnetic separator that’s best for your application, that depends on the specifics of your process. What is your product? What purity levels do you need to achieve? What is your throughput? What type of ferrous contaminants are common? These questions and more can be decisive in selecting the magnetic separator best for your application.

Ceramic & Rare Earth Magnet Separators

Permanent magnets are made from materials that are magnetically charged to create their own persistent magnetic field. Once these materials are charged they will always have a magnetic field and display attractive behavior. They only lose their magnetic field if they are exposed to a demagnetizing field, extreme heat, or physical damage caused by breakage or corrosion.

Industrial permanent magnets are often constructed of:

Ceramic or “Ferrite” materials: a mixture of iron oxide and strontium carbonate
Alnico: a combination of aluminum, nickel and cobalt
Rare earths: including samarium cobalt and neodymium.

While rare earth magnets are generally stronger than ceramic or Alnico varieties, they can also be more susceptible to corrosion. Neodymium is particularly susceptible and may not be suitable for some magnetic separation applications.

Any of Dings permanent magnetic separators can be made with either ceramic or rare earth magnets depending on the needs of the application.

Grate Magnet Separators

Grate magnets are powerful, non-electric separators designed to remove small magnetic particles from free-flowing powders and granular materials. Dings grate magnets are most often made with ceramic magnets; however, rare earth can be substituted if they’re a better fit for the specific application. While the grate’s magnetism is spread across its entire area, It’s most heavily concentrated on the smooth surfaces of magnetic tubes, and in the space near them. Dings grate magnets are built with magnetic material throughout the entire tube structure to produce a more uniform magnetic field, unlike other competing grate magnets that are partially loaded with springs and fillers

Grate magnets are often the best fit for vertical flow chute applications. They are more efficient, effective and economical than other separator types in these processes. As material is fed into a grate magnet it is passed through its magnetic separating force ensuring ferrous removal. Being permanent magnets with no moving parts, they provide cost free separation with little to no maintenance.

Dings manufactures grate magnets in a variety of designs and models: Rotary, Hopper, Easy Clean, Auto Clean, Heavy Duty Pit, Standard Housed, Drawer, Heavy Duty Frame and much more.

Heavy Duty Pit Magnet Separators

The Dings Pit Magnet, a heavy-duty type of grate magnet, was designed specifically for grain handling facilities. The pit magnet mounts securely over a receiving pit’s opening and removes any nails, screws, wire, tools, or other tramp iron from a grain stream that’s run through it. Manufactured with large 2” square magnetic tubes and wide tube spacing, the pit magnet is also ideal for any other high-volume processing operations with free-flowing powders or granular materials. Pit magnet sizes range from one to five feet square or rectangular.

Ferroplate Magnetic Separators

Ferroplates are low-cost, non-electric flat plate magnetic separators. While Dings standard versions are made with ceramic VIII magnetic material they can also be built with rare earth for applications that require it. They are designed to remove tramp iron and magnetic contaminants from processed powders and granular materials conveyed in chutes. The most popular installation is a sloping chute. An installed Ferroplate is hinged to the underside of the chute, where it can overlap an opening cut into the chute bottom. Any ferrous in the material that slides over the Ferroplate is attracted towards the magnetic face, then is held firmly on it. Dings Ferroplates provide more magnetic range and holding power than others on the market. Our Ferroplates have the capability of effectively attracting metal through a distance while securely holding that metal in a chute.

Dings Ferroplates come in several different models and design shapes that are available to meet your specific application requirements. Any Ferroplate can be custom designed.

Drum Magnetic Separators

Magnetic Drums are designed to continuously remove large quantities of ferrous metals for product purification in free-flowing powders and granular materials. Magnetic Drums also protect processing equipment from damaging iron impurities preventing costly repairs and downtime. Their self-cleaning design means there’s no interruptions in product flow for cleaning cycles. Dings drum magnets, depending on the application specifics, can be made with either high-strength ceramic or rare earth materials. Both versions always function at top efficiency, day in and day out. Dings drum magnets feature our DFC magnetic circuit to ensure a powerful, uniform magnetic field across the entire surface of the magnet.

Dings magnetic drums can be fed in any position. After mounting, the magnet arc is adjusted to match the feed location. If the application requires it, drums can be set in a multi-step sequence to improve performance and achieve even higher purity levels. Any ferrous material that makes it past the first drum will be caught and removed by subsequent drums.

Which Magnet Separator Type is Best for Your Bulk Powder or Granular Process? Dings Experts Can Help

Dings Company Magnetic Group engineering and sales staff work together from our Milwaukee, WI factory to provide outstanding customer service from experts in magnetic separation. We listen to our customers to gain an understanding of their needs and apply our experience in their trade to provide magnetic separation equipment that is sized and positioned for the best possible performance in their specific application. Contact Us at magsales@dingsco.com or call us at (414)672-7830.

Magnetic Separation for Wood and Biomass Processing

Stationary overhead electromagnet for wood recycling

For timber recycling and other biomass products such as wood chips and feed pellet the need for metal separation is twofold. First, providing your customers with the product purity they expect. Second, protecting valuable processing equipment that’s made for cutting and shredding organic material, not metal.

However, when it comes to which type of magnetic separator, that depends on the specifics of your process. What type of product are you running? How often are ferrous metals encountered in your product? What is your burden depth and throughput? What type of ferrous contaminants are common? These questions and more can be decisive in what magnetic separator solution is best for your application.

Overhead Magnetic Separators

Overhead magnetic separators, sometimes referred to as overband or overbelt magnets, are often the best solution for removing ferrous contaminants and damage causing tramp metal in most situations.

Permanent Magnets and Electromagnets

Overhead Permanent Magnetic Separators

Overhead permanent magnetic separators always have a magnetic field and don’t require any outside energy to produce it. Permanent magnets, while less expensive than their electromagnet counterparts, come with a series of benefits and drawbacks that determine which applications they are suitable for. For one, they are more space efficient. This smaller size makes them ideal for use in tight spaces. However, this means they are at their best when used in applications with lighter burden depths and smaller belt widths. Something to note when using a permanent magnet, because the magnetic field is always active, ferrous materials must be removed either manually or by use of a self-cleaning belt or other removal mechanism.

Overhead Electromagnetic Separators

Electromagnets use electricity flowing through a coil structure wrapped around an iron or steel core to create their magnetic field. Because of this, overhead electromagnetic separators allow greater control over the presence of its magnetic field. By simply cutting the power ferrous material will be released giving an electromagnet an advantage over the use of a permanent magnet in some situations. The deep toroidal shape of the magnetic field produced by an electromagnet can make it the magnet of choice for troughed belt conveyors or applications with heavier burden depths.

Self-Cleaning and Stationary Magnets

Overhead Self-Cleaning Magnetic Separators

If ferrous impurities are prevalent in your application a self-cleaning model might be best. A self-cleaning magnetic separator uses a multi-ply rubber belt with 1-inch vulcanized cleats that travels across the magnet’s face automatically discharging ferrous material saving time and labor costs. In applications where, sharp tramp metal is common, like heavy gauge nails, that can damage the self-cleaning belt an optional armor-clad Dings “Dura Belt” of stainless-steel pads and cleats is also available.

Overhead Stationary Magnetic Separators

If tramp metal is rare in the process but intolerable, an overhead stationary magnet can be an optimal choice. Without having to accommodate for the sag of a self-cleaning belt in the suspension height, use of a smaller more economical magnetic separator may be possible. Stationary magnetic separators also don’t have moving parts or drive motors that can break down. This saves labor and repair costs while minimizing down time.

Magnetic Head Pulley Separators

Magnetic pulleys are non-electric, self-cleaning magnetic separators that operate as head pulleys on conveyors to separate iron impurities from conveyed product. As the product is discharged from the conveyor, non-magnetic material follows its normal trajectory off the belt while ferrous clings to the magnetic head pulley until it is released under the conveyor as the ferrous metal leaves the pulley’s magnetic field.

Under certain situations, using a magnetic head pulley for your application can have advantages when compared to an overhead magnetic separator. An overhead magnetic separator has to pull ferrous material out of a burden through the air up to the suspended magnet. The suspension height puts a greater distance between the magnet’s face and the material to be separated necessitating the use of a larger magnet. A magnetic head pulley however, has the mechanical advantage of pulling ferrous material down to the belt at the magnet’s surface where its field strength is greatest. This may allow for higher belt speeds, resulting in increased production and productivity.

Magnetic head pulleys are best used in applications where the burden depth is shallow or in deeper depths when used in conjunction with an upstream crossbelt overhead magnet. This arrangement ensures that if a heavy burden depth causes tramp metal to be missed by one magnet, it will be caught by the other. One magnetic separator working on the bottom of the load and the other at the top. Dings manufactures three different strength series to accommodate varying burden depths and throughput volumes, Dings standard, heavy-duty and DFC Ultra.

Magnetic Deep Draw Drum Separators

Magnetic drum separators, such as Dings Deep Draw Drums, are another option for the remove of ferrous contaminants from wood and biomass product streams. Their operation is similar to magnetic head pulleys although they are not part of the conveyor belt directly. Instead material is discharged from the conveyor onto a rotating stainless-steel drum with a fixed permanent magnet inside of it. While the non-magnetic organic material follows a normal trajectory, the internal magnet holds any ferrous material to the shell of the drum until it rotates past the magnetic area discharging it underneath the drum. Due to their larger size, Deep Draw Drums allow for a heavier throughput than smaller magnetic head pulleys but cannot be used with a portable plants like head pulleys can be.

The Dings deep draw drum’s permanent magnet design outperforms electric-powered models in a number of important ways, it always operates at top efficiency and maintains a constant magnetic strength throughout the day. Deep draw drums employ Dings’ unique DFC (Dings Flux Control) magnetic circuit design that eliminates internal leakage between magnetic poles and improves separating performance. Other ‘conventional’ magnetic circuits contain air or filler material between the magnetic poles; this allows flux (magnetism) to escape (leak out) and be wasted. In Dings DFC design – blocking magnets are strategically positioned in the spaces between the magnetic poles. These redirect the flux outward, into the product, converting the wasted flux into working force -making the magnet more efficient.

SurroundScan Protector Series Metal Detection for Wood and Biomass Processing

Dings Co. Magnetic Group’s sister company, Advanced Detection Systems, engineers and manufactures metal detection systems. The Protector Series detects any ferrous, non-ferrous or stainless steel that made it past your magnetic separators. Metal detectors, when used with proper magnetic separation, complete the ferrous metal contaminant protection process. Or if metal is very rare in your process, a metal detector can be an economical and easy to install alternative to an overhead magnet or deep draw drum.

The Protector series metal detector will detect metal, alert workers and even shut down equipment before it can be damaged. The Protector’s steel construction and NEMA 4 electronics enclosure is designed for outdoor use and the removable end plate facilitates easy installation into existing processing lines. Protector series metal detectors are available as complete systems with splice sensors and metal markers

Which Magnet Separator is Best for Your Wood and Biomass Process? Dings Can Help

Dings Company Magnetic Group engineering and sales staff work together from our Milwaukee, WI factory to provide outstanding customer service from experts in magnetic separation. We listen to our customers to gain an understanding of their needs and apply our experience in their trade to provide magnetic separation equipment that is sized and positioned for the best possible performance in their specific application. Contact Us at magsales@dingsco.com or call us at (414)672-7830.

Magnetic Separation for Mining and Aggregate Production

Overhead Self-Cleaning Electromagnet in Quarry

In aggregate and mining applications the need to remove ferrous often comes down to protecting processing equipment like conveyors, screens and crushers. Tramp metal, like bucket teeth, that get through can cause catastrophic damage and costly downtime while you’re forced to make repairs. The other benefit that magnetic separation provides is enhanced product purity.

Overhead Magnetic Separators

Overhead Magnetic separators are often the best solution for removing damaging tramp metal in mining and aggregate production. However, when it comes to which type of magnet, that depends on the specifics of your application. How prevalent is tramp iron in your product? What type of product are you running? What is your burden depth? Is a lack of space above the conveyor an issue? These questions and more can be decisive in what magnetic separator solution is best for your mining application.

Self-Cleaning versus Stationary Magnets

Self-Cleaning Magnetic Separators

If tramp metal is prevalent in the mining or aggregate process a self-cleaning model might be best. A self-cleaning magnet uses a multi-ply rubber belt with 1-inch vulcanized cleats that travels across the magnet’s face automatically discharging the ferrous contaminants saving time and labor costs.

Stationary Magnetic Separators

If tramp metal is rare in the mining or aggregate process but intolerable, an overhead stationary magnet can be an optimal choice. Without having to accommodate for the sag of a self-cleaning belt in the suspension height, a smaller more economical magnetic separator may be possible. Stationary magnetic separators also don’t have moving parts or drive motors that can break down. This saves labor and repair costs while minimizing down time.

Permanent Magnets versus Electromagnets

Electromagnetic Separators

Electromagnets use electricity flowing through a coil structure around an iron core to create their magnetic field. Because of this, overhead electromagnetic separators allow greater control over the presence of its magnetic field. By simply cutting the power ferrous material will be released giving an electromagnet an advantage over the use of a permanent magnet in some mining and quarry applications. The deep toroidal shape of the magnetic field produced by an electromagnet can make it the magnet of choice for troughed belt conveyors.

Permanent Magnetic Separators

Overhead permanent magnetic separators always have a magnetic field and don’t require any outside energy to produce it. Permanent magnets are more space efficient than electromagnets. This smaller size makes them ideal for use in tight spaces. However, because the magnetic field is always active, ferrous materials must be removed either manually or by use of a self-cleaning belt or other removal mechanism.

Magnetic Head Pulley Separators

Magnetic head pulleys are non-electric, self-cleaning magnetic separators. They operate as head pulleys on conveyors to separate tramp iron and iron impurities from conveyed product. They are designed for machinery protection and product purification. As the product is discharged from the conveyor, non-magnetic material follows its normal trajectory off the belt while ferrous clings to the magnetic pulley until it is released under the conveyor as the tramp iron leaves the pulley’s magnetic field. Dings manufactures three different strength series to accommodate varying burden depths and throughput volumes, Dings standard, heavy-duty and DFC Ultra.

Which Magnet Separator is Best for Your Aggregate or Mining Process? Dings Can Help.

Dings Company Magnetic Group engineering and sales staff work together from our Milwaukee, WI factory to provide outstanding customer service from experts in magnetic separation. We listen to our customers to gain an understanding of their needs and apply our experience in their trade to provide magnetic separation equipment that is sized and positioned for the best possible performance in their specific application. Contact Us at magsales@dingsco.com or call us at (414)672-7830.

Magnetic Separation for Recycling Processes

Magnetic Separation for Recycling Applications

Whether it’s mixed stream municipal recycling or construction and demolition waste, there are always valuable materials that must be recovered. Magnetic separation lowers the labor cost and time needed for hand sorting. Ferrous metals like iron and steel are easily recovered using overhead magnets, deep draw drum magnets or magnetic head pulleys. For valuable non ferrous metals, such as copper, aluminum and brass, an eddy current separator is the best option. Dings Co. magnetic separation equipment for recycling makes the material recovery process more efficient and increases the purity of your product stream.

Overhead Magnetic Separators for Recycling

In recycling and material recovery applications where ferrous metal is common, a self-cleaning overhead magnet is often a better option than a stationary model. Self-cleaning magnetic separators come equipped with a multi-ply rubber belt with standard 1-inch vulcanized rubber cleats. This belt travels across the face of the magnet automatically discharging the ferrous metal it pulls from the product stream so it can be easily collected.

Material Recovery Facility (MRF) Overhead Magnetic Separator Design

The MRF (Material Recovery Facilities) self-cleaning magnetic separator features 3-inch tall rubber vulcanized cleats on a tough multi-ply belt. This model has the ability to sweep away large diameter cans that roll over the standard 1-inch cleat, ensuring that they get included in the separation process.

The MRF magnet design is often used in applications such as:

Commingled recyclables at material recovery facilities to obtain separate material streams.
Presorted recyclables at intermediate processing facilities (IPFs) for ensuring quality materials.
Mixed waste processing facilities to recover recyclable ferrous materials.
Organic materials at composting locations.
Shredded tires at tire recycling processing sites.

Severe Duty Overhead Magnetic Separator Design

The severe duty overhead electromagnet is specifically designed to withstand the harshest environments and toughest material recovery applications like concrete recycling and construction and demolition waste. The Severe Duty Model comes equipped with a Dings ‘Durabelt’ of stainless-steel pads and cleats. The Durabelt Prevents the underlying rubber belt from being pierced by sharp ferrous metal like rebar. Included with the severe duty overhead magnet design are a heavy-duty drive assembly, lagging on the drive pulley and reinforced suspension/mounting hardware.

Eddy Current Separators for Recycling

The key component of the eddy current separator is the magnetic rotor, which has a series of permanent rare earth magnets mounted on a support plate attached to a shaft. The magnetic rotor is surrounded by a wear shell which supports the conveyor belt. This allows the rotor to spin independently and at a much higher speed than the wear shell and belt around it.

When a piece of non-ferrous metal (such as aluminum) passes over the separator, the magnets inside the rotor rotate past the aluminum at high speed. This forms eddy currents in the aluminum which, in turn, creates a magnetic field around the piece of aluminum. The polarity of that magnetic field is the same as the rotating magnet, causing the aluminum to be repelled away from the magnet. This repulsion makes the trajectory of the aluminum greater than that of the nonmetallic material, allowing the two material streams to be separated for recycling or material recovery.

Concentric Eddy Current Separators

Depth of magnetic field is relative to the size of magnets inside the rotor. For example, the Dings 9500 concentric eddy current separator has a larger/deeper field and is ideal for recycling applications with larger sized non-ferrous in a higher through put. While the 9100 eddy current separator is better for recovering fractional non-ferrous metal up to the size of aluminum cans. The Dings concentric design has a triple layered shell consisting of an outer layer of ceramic tile and fiberglass around a heavy-duty stainless steel inner shell to protect the magnetic rotor assembly. This design lowers maintenance and replacement costs.

Eccentric Eddy Current Separators

The 9900 eccentric eddy current separators’ magnetic field is the same as the 9100 concentric version and is ideal for the same types of recycling applications. However, it’s off center “eccentric” magnet design of the rotor allows ferrous metal that made it past the upstream magnetic separator to be released from the belt as it leaves the magnetic area of the outer rotor shell. This reduces the likelihood that ferrous metal will cling to and damage the belt and shell, extending rotor life.

Deep Draw Drum Magnetic Separators

Deep Draw Drum magnets

/) are specially designed for heavy duty, high-volume ferrous recovery. This large and powerful magnetic drum has a nonmagnetic outer shell that is driven around a fixed magnet. Ferrous metal is magnetically drawn out of the material feed, held against the rotating shell, and then released at the discharge point. The Dings Deep Draw Drum magnetic separator has the rugged construction needed for separating ferrous metal from the material stream in shredded cars, scrap metals, municipal solid waste, and other recycling applications. The Deep Draw Drum can be fed at multiple positions since the internal magnet assembly is adjustable. The Dings Deep Draw Drum’s permanent magnet design outperforms electric-powered models in a number of important ways, it always operates at top efficiency and maintains a constant magnetic strength throughout the day.

Magnetic Head Pulley Separators

Dings Magnetic Head Pulleys are non-electric, self-cleaning magnetic separators. They operate as head pulleys on conveyors to separate ferrous metals from materials conveyed in bulk form. They are designed for machinery protection and product purification. Our magnetic head pulley’s magnetism is produced by an internal ceramic magnet assembly that is enclosed with a nonmagnetic stainless steel shell.

Since every recycling application has its own specific needs regarding the magnetic depth of field required, Dings Company Magnetic Group is the only company to offer magnetic head pulleys in three different magnetic strengths. The series in order of magnetic strength are standard, heavy duty and our strongest, Dings DFC Ultra. Dings magnetic head pulleys also offer various types of vulcanized lagging.

Dings Company Magnetic Group Helps You Find The Right Magnetic Separation Solution for Your Recycling Application

Dings Company Magnetic Group engineering and sales staff work together from our Milwaukee, WI factory to provide outstanding customer service from experts in magnetic separation. We listen to our customers to gain an understanding of their needs and apply our experience in their trade to provide magnetic separation equipment that is sized and positioned for the best possible performance in their specific application. Contact us at magsales@dingsco.com or call us at (414)672-7830 for help finding the right magnetic separation solution for your recycling application.

Electromagnets vs. Permanent Magnets: Pros and Cons in Overhead Magnetic Separators

Overhead Magnetic Separators

For many conveyed material applications ferrous metal contaminants can be problematic. Whether it’s the damage they can cause to your processing equipment or a reduction in the purity of your product stream, they must be removed. One of the most effective ways to do this is with an overhead magnetic separator

Overhead magnetic separators, when properly positioned over the conveyor belt or head pulley, draw the ferrous impurities out of your product. Magnetic separators can use either electromagnets or permanent magnets in their construction. Depending on the application, each type has its own benefits and drawbacks.

Types of Magnets use in Magnetic Separators

Permanent Magnets

Permanent magnets are made from materials that are magnetically charged to create their own persistent magnetic field. Once these materials are charged they will always have a magnetic field and display attractive behavior. They only lose their magnetic field if they are exposed to a demagnetizing field, extreme heat, or physical damage caused by breakage or corrosion.

Industrial permanent magnets are often constructed of:

Ceramic or “Ferrite” materials: a mixture of iron oxide and strontium carbonate
Alnico: a combination of aluminum, nickel and cobalt
Rare earths: including samarium cobalt and neodymium.

While rare earth magnets are generally stronger than ceramic or Alnico varieties, they can also be more susceptible to corrosion. Neodymium is particularly susceptible and may not be suitable for some magnetic separation applications.

Electromagnets

An electromagnet is made of a coil of conductive wire or strap that is wound around an iron or steel core. When an electrical charge is passed through this coil, it creates a magnetic field that flows through the center of the core along its longitudinal axis and circles back around the outside of the coil creating a toroidal shaped field (See image below).

As long as the electrical current is passing through the coil of the electromagnet, it will behave like a magnet. When the electricity stops flowing, the coil stops producing the magnetic field and any material bound to the magnet will be released.

Permanent Magnets vs. Electromagnets in Magnetic Separation Applications

Benefits of Permanent Magnets

One of the main benefits of using permanent magnets in a magnetic separator is that they always produce a magnetic field and don’t require any outside energy to produce it. Permanent magnets also require less space than electromagnets due to the lack of a coil structure or cooling oil. This smaller size makes them ideal for applications where space is limited like in portable plants.

Drawbacks of Permanent Magnets

While the permanence of the magnetic field is a benefit, in some magnetic separation applications it can also be a detriment because ferrous materials must be removed either manually or by use of a self-cleaning belt or other removal mechanism.

Benefits of Electromagnets

Electromagnets have greater control over the magnetic field. By simply cutting the power ferrous material will be released giving an electromagnet an advantage over the use of a permanent magnet in some metal separation applications. The deep toroidal shape of the magnetic field produced by an electromagnet accommodates the burden depth and lump size of material conveyed in troughed belts well. This can make it the magnet of choice for those applications.

Drawbacks of Electromagnets

The main drawback of electromagnets is that they require electricity to operate which is an added expense. This also necessitates running an electrical supply up to the magnets location which may not be possible in some applications. Another potential drawback of using an electromagnet in your magnetic separator is the of the shape of the magnetic field it produces. In some metal separation applications, where sharp tramp metal is common, the toroidal shape of the field holds the ferrous material vertically against the magnet’s body or self-cleaning belt. This may require the use of a protective mechanism like the Dings “Durabelt” to defend the underlying rubber belt.

Stationary vs. Self-Cleaning Magnetic Separators

Once the type of magnet has been determined to fit the application, the next question is whether a stationary or self-cleaning magnetic separator is a better option. If tramp metal is prevalent in the process, a self-cleaning model might be best. A self-cleaning magnet automatically discharges the ferrous contaminants saving time and labor costs. If tramp metal is rare in the process but intolerable, a stationary magnet can be an optimal choice. Without having to accommodate for the sag of a self-cleaning belt in the suspension height, a smaller more economical magnetic separator may be possible.

Which Magnet Separator is Best for Your Process? Dings Can Help.

Dings Company Magnetic Group engineering and sales staff work together from our Milwaukee, WI factory to provide outstanding customer service from experts in magnetic separation. We listen to our customers to gain an understanding of their needs and apply our experience in their trade to provide magnetic separation equipment that is sized and positioned for the best possible performance in their specific application. Contact Us at magsales@dingsco.com or call us at (414)672-7830.

How Do Electromagnets Work & How are Dings Electromagnets Unique?

Magnetic Field Produced by Electromagnet

What is an Electromagnet and How do they Work?

Electromagnets are a type of magnet and one we use in many of our magnetic separators. Unlike permanent magnets, an electromagnet’s magnetic field is produced by an electrical current.

An electromagnet is made of a coil of conductive wire or strap that is wound around an iron or steel core. When an electrical charge is passed through this coil, it creates a magnetic field that flows through the center of the core along its longitudinal axis and circles back around the outside of the coil creating a toroidal shaped field (See image below).

As long as the electrical current is passing through the coil, it will behave like a magnet. When the electricity stops flowing, the coil stops producing the magnetic field and any material bound to the magnet will be released. This control over the magnetic field can give an electromagnet an advantage over the use of a permanent magnet in some metal separation applications.

Dings Electromagnetic Coil Design vs. Conventional Designs

Conventional Coil Designs with Insulated Copper or Aluminum Wire

It is necessary to insulate the wires of the coil to prevent the electrical current from flowing along the conductive material and jumping between wires following its natural preferred shorter paths. The insulation creates a barrier that can’t be crossed by the current, focusing it along the coil’s path around the core resulting in the desired magnetic field. Conventional electromagnetic coils are often made with copper wire insulated with polymer or bare aluminum with Nomex® paper insulation.

The problem with this method is electromagnetic coils create a large amount of heat during use and these insulation materials can burn at those temperatures. This can cause coil burnout. To prevent this the coil must be completely submerged in cooling oil. However, as the oil heats up along with the coil it expands and requires an external expansion tank to hold the surplus oil.

Dings Anodized Aluminum Strap Coil

Dings electromagnetic coil is a wound anodized aluminum strap— an exclusive design where the anodized layer serves as the coil’s insulation. Anodized aluminum exceeds Class H insulation rating. Since the anodized layer isn’t as susceptible to burning if it’s not completely submerged, the cooling oil can be kept at a lower level that can be contained within the magnet itself. This eliminates the need for external oil expansion pipes or tanks that require maintenance and can be damaged.

Benefits of Dings Electromagnetics

Dings coil design allows for more turns around the electromagnet’s core since space is no longer needed to accommodate the polymer or Nomex® insulation material. Dings’ coil design generates more magnetism resulting in a stronger more efficient magnet than any other on the market.

Another of Dings exclusive benefits is without polymer or Nomex® paper insulation, Dings electromagnetic coil design outlasts the others and comes with an industry best 20-Year Warranty on Coil Burnout.

Dings Magnetic Group Supplies Powerful Magnetic Solutions

Dings Company Magnetic Group engineering and sales staff work together from our Milwaukee, WI factory to provide outstanding customer service from experts in magnetic separation. We listen to our customers to gain an understanding of their needs and apply our experience in their trade to provide magnetic separation equipment that is sized and positioned for the best possible performance in their specific application. Contact Us at magsales@dingsco.com or call us at (414)672-7830.

Category: Blog

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