3 Types of Ferrous Metal Found in Plastics Recycling

Metal Removed by Magnetic Separators

Metal is a major cause of equipment damage, production downtime and poor end product quality, especially when recycling materials such as plastic.  So what types of metal can be found?  Here are 3 examples taken directly from a UK plastics recycling plant.

  1. Fine metal shards and even dust – The metal found on the face of this ultra strong Rare Earth Plate Magnet is quite fine and has been lifted up out of conveyed material.  Fine iron is difficult to separate and can cause significant wear to plant and also contaminate the final product.  In this particular installation, Plate Magnets were used both suspended above the conveyor and positioned in chutes (where material flows over the magnet face), but fine iron can also be removed using Drum Magnets;Fine_Iron_on_a_Bunting_Plate_Magnet
  1. Nuts, Bolts and Screws – This is a more typical example of metal contamination that tends to be either present in the delivered reclaimed plastic or introduced into the process from plant wear or during maintenance.  Nuts, blots and screws cause significant damage to process plant and can be costly in terms of equipment repair and production downtime.  In this installation, these ferrous metal items were removed from the product stream using a Magnetic Pulley although Drum Magnets are also used;Metal Found in Plastic Recycling Bunting Magnetics-2
  1. A Large Spanner – An extreme, but not unusual, example of metal contamination.  The damage that a tool such as a spanner can cause is huge in terms of cost and downtime.  Introducing a spanner into a shredder or granulator could have disastrous consequences.  The spanner in this photograph was separated using a Magnetic Pulley.  On other plants both Drum Magnets and Twin Pole Overband Magnets are commonly used;Metal Found in Plastic Recycling Bunting Magnetics-3

We are putting together a library of metal items that have been found in process lines and would welcome your feedback and photos.  Please send us your stories to press@buntingeurope.com and we will add these to this news blog on our website.

For further details on the Bunting range of Magnetic Separators and Metal Detectors please contact our technical sales team on:

Twin Pole Overband Magnet Solution for Hanbury Plastics

Enhanced Ferrous Metal Separation from Bunting Magnetics

Bunting Magnetics Europe Ltd has worked closely with Hanbury Plastics Recycling (HPR) to provide a bespoke Magnetic Separation solution for metal separation.

From their operation in Stoke-on-Trent, HPR specialise in creating high quality plastic feedstock materials, by sorting commingled commercial, industrial and post-consumer waste into separated polymer streams of high purity.  Recycled plastics are available from HPR in a variety of formats, including bales, shred, regrind, agglomerate and compound.Hanbury Plastics Bunting Overband Magnet-7975

HPR operate 24 hours a day and continues to increase capacity for both infeed and output.  The design capacity of the plant is approximately 50,000 tonnes per year and presently HPR has an output of approximately 35,000 tonnes per year with a new 2nd line.  This equates to around 5 tph of mixed product.

Infeed material is received from a wide variety of sources including local authority MRFs.  The mixed baled material is firstly broken up in a bale breaker before passing through a Ballistic Separator from which there are 3 fractions:  -10mm fines; Fines and Paper; and +10mm material.

The +10mm fraction is then passed under a Bunting Overband Cross Belt Magnet to remove and recover the ferrous metals before passing over an Eddy Current Separator, which removes the non-ferrous metals.  The metal-free material is then processed over a series of NIR (Near Infrared Sensors) Sorting Systems to further segregate the plastic into different grades.

The quality of the end product and the subtle tuning of the final stage separation system is dependent on each stage of separation.  Bunting worked with HPR on the primary magnetic separation stage to efficiently remove the ferrous metal.  This involved several site visits from Carlton Hicks, Bunting’s Sales Manager, to assess and discuss the application and potential locations for the Magnetic Separator with HPR.  With experience gained from magnetic separation installations in many other recycling operations, Carlton was able to recommend the best solution in terms of the type, design and size of magnetic separator.

The main conveyor transporting the broken baled material is 1.5m wide and inclined at approx. 30 degrees.  Bunting assessed the application and concluded that the optimum solution was a Twin-Pole Overband Cross Belt Magnetic Separator.  Unlike single pole designs, the Twin-Pole version produces higher and stronger magnetic fields, increasing the level of ferrous metal separation.  The Overband Cross Belt Magnetic Separator is suspended across the conveyor, lifting magnetically susceptible materials such as steel cans and lids, which is then discharged to the side by a continuously revolving rubber cleated belt.  The Twin-Pole Magnetic Box is designed to stretch across the whole width of the feed conveyor, with enough excess to enable the discharge of ferrous metals well away from the feed material.

Bunting Overband Magnet over Conveyor

Roger Evans, Hanbury’s Managing Director explained the reasoning behind purchasing the Bunting magnet.  “Bunting was able to manufacture a bespoke solution based on their experience of the application rather than simply provide an ‘off the shelf’ solution.”

Bunting provide a range of metal separation solutions for the recycling industry.  For further details on the Bunting range of Eddy Current Separators, Magnetic Separators and Metal Detectors please contact Carlton Hicks (carltonhicks@buntingeurope.com) or our technical sales team on:

Hanbury Plastics Bunting Overband Magnet-7946

The Misconception of Eddy Current Separator Belt Length

3rd of 5 Misconceptions About Eddy Current Separators

Eddy Current Separators are used extensively in the recycling industry to separate non-ferrous metal (e.g. aluminium beverage cans, shredded aluminium and copper etc) from non-metallic materials.  However, there are various misconceptions as to what helps and hinders separation and this blog investigates the length of the conveyor belt.

The conveyor belt needs to be long

The length of the conveyor belt of an Eddy Current Separator ranges considerably and there are claims that longer belts improve the level of separation.  But is this true?

Firstly, it is important to consider the reason for the belt in the design of an Eddy Current Separator.  The belt is simply a way to transport the material into the rotating magnetic field or ‘separation zone’.  As discussed in the 2nd of the ‘misconceptions’ series, the belt speed can vary considerably, but why would the belt need to be long?

For optimum separation, the material needs to be settled on the conveyor belt before entering the ‘separation zone’ and this is one of the reasons given for a long belt.  However, the best level of separation is achieved when the material being fed onto the conveyor belt is via a Vibratory Feeder.  The Vibratory Feeder evenly spreads the material, preferably into a mono layer, before it drops onto the conveyor belt.  As the flow of the material is controlled by the vibration of the Vibratory Feeder and the end of the Feeder tray is close to the surface of the belt, the material settles down quickly and hence a shorter conveyor belt can be used.

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For some applications, direct feed of the material from a Vibratory Feeder with a non-metallic tray or tray tip, into the ‘separation zone’ may even negate the need for the conveyor belt at all.  However, the conveyor belt in this case would work as a cleaning device, taking any magnetic material away out of the product and away from the shell of the Eddy Current Separator rotor.

In conclusion, the length of the Eddy Current Separator belt depends on how the material is being fed and:

  • If being fed straight from a conveyor, have a long belt;
  • If being fed via a Vibratory Feeder, have a shorter belt;

Previous blogs looking at the misconceptions of Eddy Current Separators include:

Bunting provide a range of metal separation solutions for the recycling industry.  For further details on the Bunting range of Eddy Current Separators, Magnetic Separators and Metal Detectors please contact Carlton Hicks (carltonhicks@buntingeurope.com) or our technical sales team on:

Metal Recovery from Old Landfill Tips

Wheatway and Cotswold Recycling Use Bunting Magnets to Remove Steel from Old Landfill

A single Cross Belt Overband Magnet and five Magnetic Separation Pulleys supplied by Bunting Magnetics have been installed by Wheatway of Gloucester on mobile screens owned and used by Cotswold Recycling Company Limited, based near Bristol.  The screens are being used as part of a process to rework an old landfill site.

Cotswold Recycling has a two-year project for re-processing landfill on an old site near Reading, Berkshire.  The landfill originated from industrial and commercial waste and is being reworked and the area cleansed to enable the building of houses.  They are using a range of Powerscreen mobile screens to size and segregate the material.  Cotswold Recycling was established in 2001 and offer up-to-date crushing and screening equipment to hire or on contract.  Their equipment enables effective recycling, reducing costs and producing a re-useable product.

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The landfill site had approximately 400,000 tonnes of material that required processing.  Originally closed in the mid 1990’s, the site had been used for industrial and commercial tipping for over 15 years.

One issue facing Cotswold Recycling was efficiently removing any steel and ferrous metals from the material.  The company was already working closely with Wheatway, who specialises in providing engineered solutions and spares to the crushing, screening and recycling industry.  Wheatway was tasked with assessing the application and contacted Bunting Magnetics Europe Ltd.  Wheatway had previously worked with another magnetic separation manufacturer and decided to work with Bunting due to their excellent sales support and service.  Bunting proved to be flexible when working with Wheatway, something that was essential due to the nature of the project.

Initially, Wheatway designed a tower structure incorporating a Cross Belt Overband Magnet.  This was positioned between two screens and separated ferrous metals by lifting them off a 800mm wide connecting conveyor belt inclined at 30º.  The Bunting Cross Belt Overband Magnet was a twin-pole design, rather than mono-pole, resulting in a far superior level of separation.  Although there was an excellent level of separation, Wheatway then considered how to make a more flexible and mobile solution as the mobile screens were constantly being repositioned.  Wheatway contacted Bunting and then purchased five Magnetic Pulleys, one for each of the mobile screens.

The Magnetic Pulleys replaced the head pulleys of the conveyors on the output of the screens.  Bunting manufactured the Magnetic Pulley by mounting strong permanent ferrite magnets onto a steel carrier that is then encased by a tightly fitting stainless steel shell.  The magnets produce an axial magnetic field that rotates with the normal motion of the pulley.  This enables entrapped material to be freed and reduces the carryover of non-magnetic material into the reclaimed ferrous metals.  The Magnetic Pulley is a simple and very effective way to separate ferrous metals, especially when the particle sizes are below 50mm and can be designed to be retrofitted on most conveyors.

MP2

For the installation, Wheatway designed a stainless steel splitter plate, which was then bolted onto the existing framework without any need for any additional holes or modification of the screen frame.  All the screened material would then pass up the belt and any ferrous metals would be attracted to the pulley and discarded under the pulley, whilst all non-magnetic materials continued to cascade under a normal trajectory out and away into a separate pile.

Wheatway designed the retrofit to ensure that there was no reworking of the framework and utilised existing holes and fittings.  This meant that a team of three people, including Colin Smith of Wheatway and Richard Cooper of Cotswold Recycling, was able to install all the magnetic pulleys and the chutes in one day.

Each Magnetic Pulley is fitted underneath a 900mm wide conveyor belt carrying approximately 50 tonnes per hour of minus 40mm material and, depending on the area of the landfill being processed, removes up to 5% magnetics.  The magnetics are then passed on for further processing to recover, clean and reuse the steel and other ferrous metals.

Richard Cooper of Cotswold Recycling commented on the Bunting equipment, stating, “The magnetic pulleys are very good and are working remarkably well, especially considering what’s going over them.”

Bunting Magnetics design and manufacture a wide range of Metal Separators for the recycling industry and will be at the RWM exhibition at the NEC in Birmingham in September.

For further details on the Bunting range of Eddy Current Separators, Magnetic Separators and Metal Detectors please contact Carlton Hicks (carltonhicks@buntingeurope.com) or our technical sales team on:

 

3 Overband Magnet Installation Problems

Common Problems Installing an Overband Magnet

The Cross Belt Overband Magnet is one of the most commonly used Magnetic Separators.  The simple design of two pulleys mounted on a frame with a magnetic block in the middle has been manufactured for decades.  As the name suggests, the Cross Belt Overband Magnet is positioned above a conveyor, either over the head pulley, or more, commonly across the belt.

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Unfortunately, the separation performance is often poorer than expected simply because the installation is not correct.  Here are 3 typical installation issues that can be easily remedied to improve the level of separation:

  1. Being suspended too high

    Every Cross Belt Overband Magnet will be designed to operate at a specific height above the conveyor.  To accommodate an occasional surge of material, the Overband Magnet can be temporarily raised and then, as the magnetic field is further away from the conveyor belt, the separation performance falls.  Often, when the Overband Magnet is raised it is not then lowered back to the original position resulting in an ongoing poor separation performance.  If surges are common, a larger Cross Belt Overband Magnet suspended at a higher height may be the solution;

  2. Being too narrow for the conveyor

    This can occur from day one, with the Cross Belt Overband Magnet not being wide enough for the conveyor width or when the Overband Magnet has been relocated within a plant.  This results in material being lifted out of the material and then dropped back onto the conveyor as the magnetic block is not wide enough to transfer and discharge the metal outside of the belt and framework.  The only solution is often to invest in a wider Magnet;

  3. Incorrectly positioned over the conveyor belt

    Many Cross Belt Overband Magnets have a single pole in the centre of the magnet block.  The maximum level of attraction and separation is achieved directly under this centre line.  Often, and especially when the Cross Belt Overband Magnet is too narrow for the conveyor belt, the centre line is positioned to one side of the conveyor nearer the area of discharge.  However, this means that it is less likely that any ferrous metal on the opposite side of the conveyor will be separated as the magnetic field is significantly lower.  This is not such an issue with the Bunting design of Cross Belt Overband Magnet as they are all designed with two magnetic poles instead of just one;

For free advice and help with maximising the performance of any Cross Belt Overband Magnet, please contact the Bunting sales team and we can arrange to visit your site and assess the installation.  For further details on the Bunting Cross Belt Overband Magnets, please contact our technical sales team on:

Other relevant articles include:

 

The Misconception of Eddy Current Separator Belt Speed

2nd of 5 Misconceptions about Eddy Current Separators

This is the 2nd in a series of blogs discussing misconceptions about Eddy Current Separation.  Eddy Current Separators are used extensively throughout the recycling industry to separate non-ferrous metal (e.g. aluminium beverage cans, shredded aluminium and copper etc) from non-metallic materials. A recent case history details the installation at Recapture Plastics in Kent.

The belt needs to run as fast as possible.

Many users of Eddy Current Separators are focused solely on how far the item of non-ferrous metal will be thrown.  By increasing the speed of the conveyor belt of the Eddy Current Separator it is possible to produce a further throw, but does this actually aid separation?

The forces on a particle as it enters the rotating magnetic field of the Eddy Current Separator are:

A – Eddy Current repulsion from the Magnetic Rotor

B – Forward force from being conveyed along the conveyor belt

C – Gravity

D – Resultant force

Bunting Eddy Current Separator-14

All the material on the conveyor belt will be affected by B and C, but only non-ferrous metals will be affected by A, the Eddy Current repulsion.  Therefore, if the size, shape and weights were the same and there was no Magnetic Rotor, the throw would be the same.  Adding in the Eddy Current repulsion changes the trajectory of the non-ferrous particle, sending it more in an upward direction.  When setting up an Eddy Current Separator, it is best to first run non-metallic material over the unit and check the material trajectory for positioning of the splitter.  Then introduce the non-ferrous metal to check that this different trajectory enables it to throw past the splitter.  The extra force from the Eddy Current affect, should result in greater throw and hence a longer trajectory.

However, if Force B (the forward force from the conveyor) is increased and all the other forces remain constant, the resultant force vector flattens to a point where the trajectories of the non-ferrous metal particle and non-metallic material cross or are nearly the same.  At this point no separation will be achieved.

As Eddy Current Separators have different designs of magnetic rotor and the variety of shapes, sizes and characteristics of non-ferrous metal particles is extensive, there is not one belt speed that suits all and each time the application needs to be studied and understood to enable the best level of separation.

Previous blogs looking at the misconceptions of Eddy Current Separators include:

For further details on the Bunting range of Eddy Current Separators, Magnetic Separators and Metal Detectors please contact Carlton Hicks (carltonhicks@buntingeurope.com) or our technical sales team on:

Better and Cleaner Magnetic Separation at Vulcanis

Twin Pole Bunting Magnetics Overband Magnet Enhances Recovery

Vulcanis has designed and built a recycling plant to receive and recover steel and aluminium cans in Barking, UK, and purchased a Cross Belt Overband Magnet for steel can recovery from Bunting Magnetics Europe Ltd.

Presently, consumers in the UK use approximately 13 billion steel cans and 50 billion aluminium cans per annum and recycling rates are 61% for steel (Tata 2014) and 57% for aluminium (Alupro 2014).  For steel in particular, the UK government has set a target of 76% recovery by 2017 and to achieve this objective more recycling plants and initiatives are needed across the UK.

The inspiration for the new plant came from Vulcanis Managing Director, Mena Ramsis.  He explained, “I was not involved in the recycling industry and only became interested when I was attending a wedding and wondered what happened to the waste.  When I started researching I could see that there was a need for additional recycling centres right across the UK and decided to build the Vulcanis plant in Barking.”

The whole plant was designed and built by in-house engineers after two (2) years of global research and includes equipment sourced from three (3) continents.  A key part of that research focused on separation equipment including the Magnetic Separator for steel can recovery and Vulcanis ordered the Cross Belt Overband Magnet from Bunting because of the strength and design of the magnetic circuitry.

Permanent Magnets, which are suspended over conveyor belts to attract, lift and dispose of tramp steel and iron, are used, extensively across the recycling industry.  A Cross Belt Overband Magnet consists of two pulleys either side of a magnetic box.  A belt then runs around the pulleys, driven by either an electric or pneumatic motor.  Metal is attracted up onto the surface of the magnet when it meets the rotating belt.  Cleats on the moving belt then move the captured metal away from the conveyor and out of the magnetic field where it is discharged into a collection bin.

Bunting Vulcanis-1179-2

When Vulcanis researched Magnetic Separators, they found that the Bunting design was fundamentally different to those proposed by most other suppliers.  The most common design of Cross Belt Overband Suspended Magnet uses a magnet box that projects a single magnetic field down onto the conveyor belt.  This is otherwise known as a ‘Single Pole’ magnet and is used commonly on mobile crushers.

Vulcanis identified that the separation performance of traditional ‘Single Pole’ magnets was limited and if recovered steel cans failed to get lifted when passing through that single area of maximum magnetic intensity, then they were missed completely.  The Bunting ‘Twin Pole’ Cross Belt Magnet projected two separate strong magnetic fields down onto the surface of the conveyor belt and so doubled the chance of capturing the steel cans, thus maximising recovery.

Ramsis first met Bunting at the RWM exhibition in Birmingham and was immediately impressed with the professionalism of the Bunting team.  Carlton Hicks, the Bunting UK Sales Manager, demonstrated the strength of the Cross Belt Overband being displayed on the stand and after assessing similar Magnetic Separators on other stands at the show, Ramsis quickly concluded that the Bunting design was magnetically superior and stronger.

Ramsis was impressed with the Bunting team, “Carlton and his colleagues were really helpful at the RWM exhibition and took time to demonstrate their equipment.  They made us feel welcome.  I recall my father betting Carlton £10 that he would be able to remove a bolt from the surface of the Cross Belt Overband Magnet.  Firstly, they held the bolt at 250mm and it shot up onto the surface of the magnet.  And then my father tried to remove it, which he couldn’t.  I don’t believe that the bet has been paid as yet, although we did buy the Overband!”

The Vulcanis plant is designed to receive 2 tonnes per hour of mixed materials with no organics.  The materials are received from across the UK, including as far north as Glasgow, often from existing recycling plants that are unable to produce a clean end product of separated metal or plastic.  Plastic recycling companies send Vulcanis by-products, often destined for landfill, who then process the material, removing all the metal, before selling the clean plastic back to the by-products supplier.  Due to the variable infeed, the split of the plastics, steel and aluminium output varies considerably on almost a daily basis.  Presently, approximately 10% of the infeed to the plant goes to landfill, whilst the aim is to reduce this to zero.

Despite only starting receiving materials in late summer 2014, the plant is already at 40% capacity, operating 8 hours per day, 5 days per week.  The output material of steel and aluminium is over 99% pure with a very high proportion being exported.

Bunting Vulcanis-1134-2Mena Ramsis explained the reason for their success and their vision for the future, “When I had the first idea for the plant, the support I had from my family was amazing.  I have always been inspired by my Grandmother and Father and they gave me the confidence to develop something that many people doubted would be successful.  We are building our business by offering our suppliers and partners favourable commercial terms and on the basis of opening up new opportunities for companies to reduce their waste and recover more material.  The response from the industry has been incredible and we are already looking at expanding the plant.  Our aim is to be processing 12 tonnes per hour in the next 5 years.”

Carlton Hicks added, “Working with Mena and Vulcanis has been a pleasure.  Their attention to detail has been acute and this meant that we were able to demonstrate that the Bunting design of Overband Magnet was exactly what they needed to maximise steel can recovery.  Although I am still waiting for my £10.”

Bunting Magnetics designs, manufactures and supplies a wide range of metal recovery and separation equipment for the recycling industry.  For further information, please contact the Bunting sales team on:

Phone: +44 (0) 1442 875081
Email: sales@buntingeurope.com
Web: http://www.buntingeurope.com