Defining Plastics Recyclability

Global Definition of Recyclable Plastic Packaging and Products Released

The global outcry of hostility against plastic products has been gathering momentum since the end of 2017 and, subsequently, politicians and governments have pledged to introduce measures to reduce plastic waste.   However, many of these new policies have been deemed to be popularist and lacking in substance.

plastic-bottles

Many governments, including the European Union, have set recycling targets that have been questioned by the recycling and plastics industries.  The EU has made a pledge to have all plastic packaging recyclable or reusable by 2030, a far more aggressive strategy that the UK Government’s plan for plastic waste reduction.

However, until recently, there has not been a definition to govern the use of the term “recyclable” and so how could any of those targets be quantified?  Due to the public outrage about how plastic waste is damaging our planet, politicians have wanted to be seen to take urgent action, but maybe a more considered approach is needed.  Should the first step be to engage with:

  • Plastic product designers and producers;
  • Companies who will ultimately recycle the products;
  • Businesses that will use the recycled plastic products in the manufacture of new products.

One issue that has often plagued the waste sector is the defining the terminology.  Even the classification of “Waste” differs from country to country.

However, two leading global international plastics recycling organisations have worked together to define the term “recyclable” in terms of plastic products and packaging.  In July 2018, Brussels-based Plastic Recyclers Europe (PRE) and the Association of Plastic Recyclers in Washington, USA have concluded that there are four conditions that define a plastic product as being “recyclable”.  These are:

  1. The product must be made with a plastic that is collected for recycling, has market value and/or is supported by a legislatively mandated program;
  2. The product must be sorted and aggregated into defined streams for recycling processes;
  3. The product can be processed and reclaimed/recycled with commercial recycling processes;
  4. The recycled plastic becomes a raw material that is used in the production of new products;

Technology already exists to help with the sorting of plastic waste into defined streams.  Additionally, there is processing equipment available to remove contamination such as metal (Magnetic Separators, Eddy Current Separators, Metal Detectors) and other contaminants (Optical, X-Ray, Infra-Red).

A recent case history report highlighted how EcoVyn, a PVC compounder in the UK, already processes 1000 tonnes of plastic waste each month of which 80% is post-consumer.

Bunting Magnetics Drawer Magnets at Ecovyn

Such clarity of the definition of whether a plastic product is really “recyclable” can only be beneficial, assisting product designers, users and recyclers.  However, it remains unclear whether the EU, UK and other governments will use this new definition when setting their recycling and plastic waste targets.

For further information metal separation equipment designed for removing metal from plastic waste and in other recycling applications, please visit our website or contact us on:

Phone: +44 (0) 1442 875081
Email: press@buntingeurope.com
Via the website

Other Plastic Waste & Recycling Articles

EcoVyn Reduce Waste by 94% with Bunting Drawer Magnets

Magnetic Separators Remove Contamination from Plastic Waste

EcoVyn Ltd has installed two Bunting Drawer Filter Magnets to remove ferrous metal contamination from plastic waste.  Since the installation of the magnetic separators, EcoVyn has reduced their waste by 94%.

Bunting Magnetics Drawer Magnets at Ecovyn
Bunting Drawer Filter in situ at EcoVyn

EcoVyn Ltd is at the forefront of PVC compounding and brings pioneering new technology to the market place.  They offer one of the most advanced and innovative production processes in the UK producing reprocessed, blended and virgin compounds for a variety of applications.

EcoVyn first met Bunting at the Interplas international plastics exhibition in September 2017.  The company use a high proportion of plastic waste, of which 80% is post-consumer.  Presently, EcoVyn processes 1000 tonnes per month of good quality reclaimed plastic waste, which they plan to increase to 16,000 tonnes per annum.  The cleansed plastic waste is blended into virgin material, resulting in a 90% output of grade A product.  Waste generated during the manufacturing process is also recycled leaving less than 1% being discarded.

Bunting Magnetics Drawer Magnets at Ecovyn
Granulated plastic waste

However, plastic waste is often highly contaminated with metal.  Metal Detectors were already installed to remove the metal contamination, but the reject rate was very high with over 60 tonnes of waste being generated, of which a high proportion was good quality plastic.

At Interplas, EcoVyn explained the problem to the Bunting team who agreed to conduct a site review.  During the review it was concluded that easily removable magnetically-susceptible metal could be removed, leaving the metal detectors to detect and separate non-ferrous metals.  This would then significantly reduce the number of metal detector rejections and, therefore, the amount of waste generated.

After a review of the process, Drawer Filter Magnets were recommended to be installed between the screw conveyor transporting the 8-10mm sized infeed material and the metal detector.  The metal-cleansed material would then pass onto a pulveriser before continuing through the process.

The Bunting Drawer Filter Magnet is used widely in the plastics industry and enables the simple and effective removal of ferrous metal from free-flowing materials.  The Drawer Filters installed at EcoVyn have two rows of high strength Rare Earth Neodymium Magnets.  The top row has two Tube Magnets with three in the second row aligned to sit below the gap in the top row.  This ensures that all the product strikes at least one of the Tube Magnets, where ferrous metal is attracted by the strong magnetic field and captured.

Bunting Magnetics Drawer Magnets at Ecovyn
Ferrous metal captured on the surface of the Tube Magnets

After the installation of Drawer Filter Magnets, the amount of waste was reduced from 60 tonnes to 4 tonnes.

Since installing the Drawer Filter Magnets, EcoVyn has established that a 20 minutes cleaning frequency is required, highlighting the high level of metal contamination commonly found in plastic waste.  The ferrous metal found captured on the Tube Magnets ranges from small fine ferrous dust to nails, washers, steel sheet shards and electrical capacitors.

Bunting Magnetics Drawer Magnets at Ecovyn
Ferrous metals captured by the Bunting Drawer Grate Magnet including nails, a capacitor, washer, wire and steel sheet shard

Following the installation of the Bunting Drawer Filter Magnets, controlled laboratory tests have been conducted at Bunting’s Master Magnets facility in Birmingham which indicated that 99.9% of all ferrous metals had been removed.

The final plastic product produced by EcoVyn is then used to manufacture products such as pipe, internal windows, beading, picture frames, and shoe soles.

For further information on separating metal from plastics during the production of the virgin product or during the recycling process, please contact the Bunting team on:

Hillhead Attracts Bunting Europe

Bunting Europe Exhibit at Hillhead for the First Time

Magnetic Separators and Metal Detectors for the quarrying, mining and recycling industry will be on show on stand C9 at this year’s Hillhead exhibition (Hillhead Quarry, Buxton, 26-28 June 2018).

Bunting Master Magnets at RWM17

The joint Bunting Europe and Master Magnets stand will feature Permanent Overband Magnets (self and manual clean designs) and two different types of Metal Detector (the TN77 and QTA).

“Hillhead has always been a really important exhibition for Master Magnets,” said Dave Hills, Bunting’s Head of Sales.  “The Master Magnets Overband Magnets and Metal Detection Ltd range of detectors are widely regarded as industry standards for both quarrying and recycling.”

Held in a limestone quarry in the heart of the Derbyshire countryside, Hillhead is the largest exhibition of its kind anywhere in the world. Continually adapting, it provides a spectacular and unique setting for exhibitors and visitors alike to do business amongst live working demonstrations and static displays.

aggregate-industries-tn77-e1528271468785.jpg

Many quarries use the combination of a Permanent Overband Magnet and Metal Detector to protect processing equipment such as screens, crushers and conveyor belts.  The Overband Magnet removes any magnetic tramp metal leaving the Metal Detector to identify non-magnetic metal parts such as manganese steel digger teeth.

“The recycling of construction waste continues to grow in importance and features strongly at Hillhead,” said Dave.  “With equipment such as the Mastertrax Mobile Eddy Current Separator, we have practical solutions for removing ferrous and non-ferrous metals.”

May through to July is a very busy exhibition period for Bunting Europe and Master Magnets.  Hillhead is just over one month after the very successful IFAT waste and recycling show in Germany and is followed by the Waste ’18 exhibition (Warwickshire Exhibition Centre, 5 July) and CARS (NAEC Stoneleigh, 11-12 July).

“Exhibiting at these events is so important,” explained Dave.  “We meet both existing and potentially new clients and can also show them what our equipment can do.”

For further information on the Magnetic Separation and Metal Detection equipment on display at Hillhead, please contact Dave Hills on:

Phone: +44 (0) 1442 875081
Email: dhills@buntingeurope.com
Via the website

Master Magnets Mobile Eddy Current Separator (1200)

Metal Separation Demos Ignite Interest at IFAT 2018

Visitors to IFAT 2018 Enthralled by Working Magnetic Separators

An Eddy Current Separator was violently expelling non-ferrous metals from plastic waste on one side of the stand, whilst large chunks of fragmented stainless steel were being separated by the SSSC on the other.  ‘Seeing Is Believing’ was very much the basis of the Bunting and Master Magnets stand at IFAT 2018 (14th – 18th May 2018).

“We wanted to showcase our metal separation technology,” explained Dave Hills, Bunting’s Head of Sales, “and that meant having production-sized equipment operating on the stand.  The positive reaction of visitors highlighted the importance of being able to show metal being separated.”

IFAT is the first major waste and recycling exhibition of 2018 in Europe, featuring 3,305 exhibitors and over 141,000 visitors.  Key topics discussed during the week-long show included the filtering of microplastics; more effective recycling of plastics; and the digital transformation of the entire industry.

“Effective metal separation is vital for the successful recycling and reuse of many secondary materials,” said Dave.  “As a specialist in Magnetic Separation, we believed that the IFAT show provided the perfect platform to show recycling companies what is possible.  The show proved to be exceptionally successful and we are now in discussion with companies all over the world.”

Following the IFAT exhibition, many companies who visited the stand are sending samples to the Master Magnets laboratory in the UK for controlled tests to confirm the separation capability of both the Eddy Current Separator and Stainless Steel Magnetic Separator.

“There was a lot of interest in the Stainless Steel Magnetic Separator.  Stainless steel is a problematic material and, due to it’s hardness, can cause real problems in granulators and shredders.  Visitors were often surprised to see large fragmented stainless steel being attracted and separated.  It has generated a huge amount of interest and there is a lot of work to do.”

For further information on the Magnetic Separation equipment on display at IFAT, please contact Dave Hills on:

Phone: +44 (0) 1442 875081
Email: dhills@buntingeurope.com
Via the website

3 Magnet Audits Conducted For Food Safety

Testing Magnetic Separators in Food Processing Plants

In one week, we have conducted Magnetic Separation Audits at three separate UK food processing plants.  The audits form part of the quality management system of each company and are used for both internal and external food quality and safety assessments.

A Magnetic Separation Audit involves the physical testing and inspection of all Magnetic Separators.

Physically Testing the Magnetic Strength

The first part of the inspection assesses the magnetic strength.  This involves using a Pull Test Kit which includes a spring balance and various sizes and shapes of magnetically susceptible steel test pieces.  A Gauss Meter is not used as the readings can be inaccurate and variable.  The physical test involves placing the steel test piece on the surface of the magnet (on a magnetic pole) and measuring the amount of force (in kgs) that is needed to remove the item from the surface of the magnet.  This is then repeated and an average reading recorded.

Visually Assessing the Magnet

The second set of tests involve the visual inspection of the Magnetic Separators and we are checking for:

  • The amount of metal contamination captured by the Magnet;
  • Signs of damage or wear;
  • Weld integrity;
  • Fixings and any related safety issues (e.g. missing restraining nuts);
  • Cleaning regimes and ease of cleaning;

Findings

In the three recent audits there were a number of findings including:

  • Magnetic Separators were in locations where it was extremely difficult to clean and may be considered a safety risk;
  • Welds on a Magnetic Separator had been eaten away by the acidic product resulting in liquid penetrating the Tube Magnet.  This caused the magnets to expand within the stainless steel casing and also destroyed the magnetic field;
  • Damaged Tube Magnets
    Tube Magnets where the welds have failed and liquid has seeped inside the stainless steel casing causing the magnets to expand and lose all magnetic strength
  • The magnetic strength of some Magnetic Separators (especially those that had been installed for some time) was very poor and the level of separation would be minimal;
  • In some locations, Magnetic Separators had been removed from the process but were still registered in the system;
  • The positioning of some Magnetic Separators could be changed to improve the metal separation performance;

Action

Following the Magnetic Separation Audit, a full report, with all the test results, is written and submitted with recommendations.  This then forms part of the food processing company’s internal quality audit system and is refereed to when there are inspections from external third parties and customers.  Commonly the audit is repeated on a annual basis using the same test parameters.

Similar audits are also undertaken in other industries including Plastics Production and Recycling.  An annual health check ensures that the Magnetic Separators are performing to their maximum potential and achieving the separation goals for which they were originally installed.

For more information on the issue of Metal Contamination and Metal Separation, or to arrange a free onsite survey and audit of a particular plant or process, please contact the Bunting team on:

Phone:  +44 (0) 1442 875081

Email:  sales@buntingeurope.com

Via the website

Polymer Training and Innovation Centre Protected by Bunting Drawer Filter Magnet

Magnetic Separator Technology for Plastics Training

The Polymer Training & Innovation Centre in Telford has added a Bunting Magnetics Drawer Filter Magnet to the range of equipment at their plastics manufacturing training facility.  The FF Drawer Filter Magnet attracts and captures any fine and coarse magnetically susceptible materials that enter the plastics manufacturing process.

Bunting FF Grate Magnet
A Bunting Magnetics Europe FF Grate Magnet included in a plastics production line at the Polymer Training and Innovation Centre in Telford

The Polymer Training & Innovation Centre provides polymer training and consultancy, specialising in injection moulding, blow moulding and extrusion training.  They are a technical training and consultancy business that is owned by City of Wolverhampton College.

At their Telford training facility, the Polymer Training & Innovation Centre has working production-sized plastics manufacturing equipment for injection moulding, blow moulding, thermoforming, materials handling, and a wide range of other important ancillary equipment.

Technical Trainer, Andrew Dermody, explained the importance of trainees having practical training on the equipment.

“We have great support from the industry and equipment manufacturers such as Bunting.  This support means that we can deliver practical training, with a hands-on approach, and that is the best way for our delegates to learn.  Having the Drawer Filter Magnet installed exactly as it would be in a production plant, is an ideal way to show our students best-practice and highlight the importance of metal removal.”

Bunting FF Grate Magnet

The training facility at Telford was refurbished in early 2017 and Bunting supplied the FF Drawer Filter Magnet in March 2018.  The FF Grate Magnet is bolted onto the bottom flange of a Summit Systems fed hopper.  The Magnetic Separator has a transparent front plate so that operators are able to see the material passing through or held within the system.  Virgin plastic beads fall from the hopper through two rows of high strength Tube Magnets, which attract and hold any magnetically susceptible materials.  The Tube Magnets use ultra-strong, permanent, Neodymium Rare Earth Magnets.  The cleaned plastic beads are then fed into the Engel injection moulding machine.  Removing all metal contamination ensures that the final plastic product is free from defects and reduces the amount of waste and potential damage to moulding machines.

Bunting FF Grate Magnet

On a regular frequency, dictated by the amount of metal captured, the Tube Magnets are removed as one complete assembly from the housing and cleaned.  The design of the Drawer Filter Magnet means that removal of the Magnet Assembly is quick and easy, keeping maintenance times to a minimum.

“The Bunting design is good as it is very visible,” said Dermody.  “Often Magnetic Separators are placed out of sight in hoppers, which means that they can be forgotten.  In this installation, the Drawer Filter Magnet is right in front of the machine operator and the clear front allows easy visual checking of the magnets.”

Bunting also supplied Drawer Filter Magnets for use in the classroom and the Polymer Training & Innovation Centre plan to incorporate ‘metal separation’ as one of the course topics.

The Drawer Grate Magnet is widely regarded as standard for the plastics industry and Bunting has supplied thousands to plastics manufacturing operations globally.

“It is great that delegates are able to see, in practice, the importance of having good Magnetic Separation equipment in the plastics process,” said Tom Higginbottom, Bunting’s Sales Engineer.  “Even with virgin raw materials, there is always a small amount of fine ferrous metal contamination and there is always the risk of larger tramp iron that could seriously damage the injection moulding machine.”

On the 18th April 2018, the Polymer Training & Innovation Centre is staging the Technivation event at their recently upgraded training facility in Telford.  During the day there will be a series of short technical presentations, the opportunity to experience their Polymer on-line simulation software, and the chance to meet and talk with primary and secondary equipment suppliers including Bunting Magnetics.  Visitors will be able to learn more about Polymer Apprenticeship’s and Funding and discuss their organisations own training requirements.

For further information on separating metal from plastics during the production of the virgin product or during the recycling process, please contact the Bunting team on:

Bunting FF Grate Magnet
A Bunting Magnetics Europe FF Grate Magnet included in a plastics production line at the Polymer Training and Innovation Centre in Telford

Export Orders Secured at Ceramitec 2018

Electro Magnetic Filters Ordered by Turkish Ceramics Producer

Bunting’s first time as an exhibitor at Ceramitec 2018, the leading exhibition for ceramics and ceramic technology held in Munich, Germany (April 10-13), proved to be a huge success.

Ceramitec 2018“We did not expect to secure orders on the stand,” said Dave Hills, Bunting’s Head of Sales, “and were thrilled to have an order placed for two Electro Magnetic Filters from a ceramic producer in Turkey.”

Bunting was exhibiting alongside ceramics and mineral processing magnetic separator specialist Master Magnets.

” When we [Bunting] acquired Master Magnets [January 2017] our aim was to expand our product portfolio and end-markets.  For decades, Master Magnets has been a leader in the design and manufacture of high intensity magnetic separators for the ceramics and mineral processing industries.  At Ceramitec, the global awareness of the Master Magnets brand was very evident.”

During the 4-day exhibition, Bunting and Master Magnets received enquiries for:

Ceramitec 2018Magnetic Liquid Traps – installed in pipelines with high intensity Rare Earth Magnets removing fine iron from slips and glazes;

Drawer Filter Magnets – installed on dry process lines to remove free and tramp iron, protecting mills and other processing equipment;

Rare Earth Roll Separators – used to remove weakly and para magnetic materials and minerals from non-metallic bodies such as Spray Dried Ceramics, Feldspar and Silica Sand;

Induced Roll Separators (IMR) – used for the continuous extraction of weakly and para magnetic particles from non-metallic minerals such as feldspar and silica sand;

“Ceramitec proved to be a resounding success.  We are going to be busy confirming our magnetic separator recommendations and also conducting laboratory tests in the Master Magnets laboratory in Birmingham, UK,” said Dave.

For further information on Bunting Magnetics and Master Magnets and our range of magnetic separation equipment designed for purifying ceramics and non-metallic minerals, please visit our websites or contact us on:

Phone: +44 (0) 1442 875081
Email: press@buntingeurope.com
Via the website

Ceramitec 2018

Search For Recycling Industry Representation in Germany

Germany Based Representative Required to Support Developing Business in the Recycling Sector

With the expanded Bunting and Master Magnets product portfolio of Magnetic Separators, Eddy Current Separators and Metal Detectors, the search has started for a new representative in Germany for the recycling sector.

“With the addition of the Master Magnets range of separation equipment, we have identified exciting opportunities in the recycling sector in Germany,” explained Dave Hills, Bunting’s Head of Sales.

Bunting and Master Magnets are exhibiting at the international waste and recycling exhibition IFAT (May 14-18, Munich, Germany) and are looking to find and appoint a new local representative before the start of the event.

“We now have one of the most extensive and complete ranges of Magnetic Separators and Metal Detectors in the world.  We are already exporting separation equipment to Germany and other countries, but recognise that we need a locally based representative,” said Dave.  “This is a great opportunity and we are looking forward to developing a long-term relationship with a recycling industry specialist.”

The expanded range of separation equipment used in the recycling sector includes:

Stainless Steel Separator

The revolutionary Stainless Steel Separator is installed after primary Magnetic Separation and Eddy Current Separation to remove either weakly magnetic materials from the primary product to produce a clean recycled material (eg UPVC window frames, recycled plastics, etc), or to recover valuable materials (eg stainless steel and PCBs).

Master Magnets Recycling Lives-7172Eddy Current Separators

The Eddy Current Separator (ECS) is an advanced metal sorting unit that is capable of separating non-ferrous metals such as aluminium and copper from dry recyclables.  A mobile Metal Separation Module incorporating the Eddy Current Separator and a high intensity Magnetic Drum (called the ‘Mastertrax‘) has proven very popular.

Permanent Overband Magnets

Bunting Master Magnets at RWM17

Mastermag Overband Magnetic Separators are renowned around the world as the most effective units for the continuous removal of tramp ferrous material from a product stream.  Simply suspended across a conveyor belt, metal is lifted up and then discharged using a self cleaning belt.

Metal Detectors

Under the well-known brand, Metal Detection Ltd, Bunting has a varied range of Metal Detectors to suit many different applications. There are designs to suit a wide range of applications and sensitivities.

Magnetic Separators

Other Magnetic Separators in the range include Pulley Magnets, Drum Magnets, Scrap Drum Magnets, Electro Overband Magnets, and a wide range of smaller equipment including FF Drawer Grate Magnets and Plate Magnets.

For further information or to express interest (for representing Bunting in Germany or any other country), please contact Dave Hills on:

Phone: +44 (0) 1442 875081
Email: dhills@buntingeurope.com
Via the website

Changes in E Waste Management Highlighted at IERC 2018

Future of Electronics Recycling Discussed at 17th International Electronics Recycling Congress

IERC 2018 closed on Friday 19th January 2018 with a stark warning that changes are needed in the global management of E-waste.  Attending the congress were 480 international experts from 42 countries.

WEEE E WasteBunting Magnetics Europe’s Managing Director, Simon Ayling, was at the congress for the first time.

“All the leading companies and organisations involved in E-waste were present at the congress,” said Simon.  “There was a very honest and open assessment of the present state of the industry, with a focus on what needs to change.”

Many visitors to the Bunting Magnetics stand had issues with separating Stainless Steel.

“Stainless steel is clearly a major issue when processing WEEE.  Up until now, it has been difficult to effectively [physically and economically] extract the stainless steel.  This then causes problems with shredder wear and the contamination of the end product.  With the HISC and SSSC, we have Magnetic Separation solutions for both small and large sized Stainless Steel.”

At IERC 2018, there was a focus on change.  As developing countries introduce tighter restrictions on the shipment of waste in general [EPPM – China raises drawbridge on incoming overseas plastic waste], a more holistic approach is needed.

New technology, like the Bunting Stainless Steel Magnetic Separator, and increased automation were identified as being vital to improve WEEE recycling rates.

Bunting Master Magnets at RWM17

The amount of E-waste is ever-increasing and the shrinking product size is making recycling increasingly difficult.  Rising collection costs and falling value of the end recycled product may lead to more localised e-recycling.  There also needs to be a clear political strategy with a standardisation of regulations.

WEEE E Waste“It was clear that the industry faces a challenging future,” observed Simon.  “Being able to successfully recycle WEEE can be prohibitively expensive and is further complicated with local and global environmental regulations.  Companies involved in processing E-waste are having to continually modify their businesses to survive in an ever-changing industry.  Hopefully, our Magnetic Separation technology will help.”

For further information on Metal Separation including Stainless Steel Recovery and Removal, or to assess the right Magnetic Separator or Metal Detector for a specific application, please contact us on:

Phone: +44 (0) 1442 875081
Email: sales@buntingeurope.com
Via the website

The Challenges of Removing Fine Iron from Powders

Magnetic Separators Designed for Processing Powders

Removing metal contamination when the tramp metal and material is granular is far more straightforward than when in a powder form.  To determine the best solution to remove fine iron contamination from powders, it is necessary to have a good understanding of the way the fine materials behave.

Powders are produced and used in a wide variety of industries including food, pharmaceuticals, refractories, and chemicals.  It is estimated that 80% of materials used in industry are in a powdered form.

flour-791840_960_720A ‘powder’ is defined as fine dry particles produced by the grinding, crushing, or disintegration of a solid substance.  The nature of a powder means that the handling and processing tends to be problematic as powders exhibit similar properties to both solids and liquids.

Metal contamination, commonly in an iron form, can be introduced into a material at any stage within a process.  Tramp metal that is undetected and remains in the product before the powder production stage, becomes significantly reduced in size and, subsequently, increasingly difficult to extract.

Magnetically susceptible metal contamination (i.e. iron) is commonly removed using Magnetic Separation Equipment, which traps metal using Ceramic Ferrite or Rare Earth Neodymium Iron Boron (Neodymium) Magnets.  Although there are Magnetic Separators where the magnetic field is produced via an electrical current, the vast majority utilize permanent magnets such as Ceramic Ferrite and Rare Earth Neodymium Iron Boron (Neodymium).  Ceramic Ferrite Magnets produce low strength but deep magnetic fields, while Neodymium Magnets create the strongest permanent magnetic presently commercially available.

Where Does The Metal Originate?

Metal contamination commonly originates in a powder from two sources:

  1. Primary large tramp metal, such as a nail, screw or bolt;Tube Cartridge Magnets Bunting Magnetics-5
  2. Primary or Secondary fine tramp iron. Primary fine iron or magnetic particles are often present in the raw material.  This originates from primary processing, transportation, or even naturally occurs in the original material.  Secondary fine iron originates from a larger tramp metal source that has been reduced in size during the process.  Typically, this could be from a nail, screw or bolt that has been through a size reduction process, or from damaged or worn processing equipment.  Another common source of secondary fine iron contamination is rust, falling into the process from weathered and worn processing equipment such as chains, hoists, and building cladding.

The separation and detection of tramp metal is easier when the metal contamination is in a larger form and can be successfully removed using a wide range of suitable Magnetic Separators and Metal Detectors.  Magnetic Separators using standard strength Ceramic magnets, with deep magnetic fields, are ideal.  A good example is the Plate Magnet, often installed in a chute, in a housing, or as part of an In-Line Magnetic Separator.

Quicktron05A_Sodium Bicarbonate 2

Larger metal contamination is also easier to detect on a Metal Detector.  Metal is detected as it passes through the coil of the Metal Detector and an automatic reject system removes it from the flow.  For detection, the magnetic field generated by the Metal Detector has to see a state change.  Finer sized metal produces a lesser state change and thus increases the difficulty in detection.

In a project in Pakistan, a processor of fine Sodium Bicarbonate is using a Quicktron Metal Detector to remove the larger tramp metal.

Removing larger tramp metal with a Magnetic Separator and Metal Detector prior to the processing stage not only prevents the metal from being reduced in size (e.g. converted into a secondary source of fine iron contamination), but also protects delicate processing equipment such as granulators, shredders, and mills from being damaged by the metal.

Once in a powder form, there are processing parameters to consider when assessing the optimum method to remove fine iron contamination.

How Does a Powder Flow?

When a powder is sprinkled, it remains light and free.  However, when the same powder is vibrated or compressed, it may become very dense and even lose the ability to flow.

Individual grains in a powder cling to each other in clumps, in accordance with the Van der Waals force.  This coagulation often results in the fine iron being trapped in among clean product.  The ability of any Magnetic Separator to attract, hold and separate the fine iron is dependent on the iron being as close to the magnetic field as is physically possible.  If the fine iron contacts the surface of a Magnetic Separator with a high strength magnetic field, it will be held.  However, when the fine iron is held inside a coagulation of powder, then it could be held out of the reach of the maximum magnetic force.  Thus, it will not be separated.

The way a powder flows impacts on the design of the Magnetic Separator.  Powders flowing in a hopper may experience classic flow problems such as ratholing, bridging or flooding, all of which could be exacerbated by the design of Magnetic Separator.

Different Designs of Magnetic Separator

Plate Magnets Bunting Magnetics-9797High strength magnetic fields, as produced by Neodymium, are needed to capture fine iron metal contamination.  There are four main magnet configurations suitable for handling powders.

  1. Tube Magnets (also known as Rod Magnets and Cartridge Magnets), often in a multi-rod Grate configuration;
  2. Flat-faced Magnetic Plates;
  3. Cone-shaped Magnets;
  4. Magnetic Drums with a curved magnetic arc;

Although occasionally a Tube Magnet may be used on its own, it is more commonly part of a larger multi-cartridge Grate system.  The Magnetic Grate is designed to fit inside a hopper, or can be supplied complete with a housing (i.e. as a Drawer Filter Magnet).ff-neo-4

In operation, powder falls freely onto the surface of the Tube Magnet where fine iron strikes the surface and is held by the strong magnetic field.  To ensure that the powder makes contact with the Cartridge surface, deflectors are often deployed above the gaps between the Cartridges.

Powder build-up on the surface of a Magnetic Cartridge will reduce the separation efficiency.  Also, in severe cases, a slight build up on the surface of the Cartridge may quickly cause a blockage of the whole housing.

Such blockages can be prevented by ensuring that there is optimum space between the Magnetic Cartridges.  Also, in some cases, the mounting of an external vibrating motor on the side of the hopper or housing will provide enough disturbance to prevent any material coagulation.  The frequency of the vibration needs careful consideration as it could affect the flow ability of the powder.  Additionally, when vibrators are used, the Magnetic Cartridges need to be manufactured to withstand prolonged periods of vibration.

Bunting Teardrop Tube Magnet

‘Teardrop’ shaped Tube Magnets are specifically designed to stop the build-up of fine powder on the surface.  The sharp edge of the teardrop faces up into the product flow and allows material to flow around the edge and into the magnetic field.  Magnetic particles are captured and held underneath the Tube Magnet.

Flat-faced Magnetic Plates are ideal when it is possible for the material to flow over the surface.  For fine iron removal, the Magnetic Plates would use high strength Neodymium Magnets.  This magnetic field is further enhanced when a Tapered Step is added to the face of the magnet.  Captured iron migrates behind the step and away from the material flow, reducing the risk of re-entering the cleansed product.

As well as being fitted into chutes, Magnetic Plates are incorporated into housings.  The Plate Housing Magnets resist bridging and choking to remove tramp iron and ferrous fines from flow-resistant bulk materials.  The stainless steel housings mount easily to enclosed spouting or directly on processing equipment.

There are optional square, rectangular, and round adapters for easy connection to existing chute work.  A baffle at the top of the housing helps break up clumps and directs product flow over the unit’s two powerful Plate Magnets.

Bunting Magnetics In Line Magnet

Plate Magnets are also used in In-Line Magnets and there are two designs:

  1. Gravity In-Line Magnets (GIM) – The Plate Magnets are positioned in round, sloping spouting where material is under gravity flow.  For effective tramp metal capture, the spouting should be angled no more than 60° from horizontal;
  2. Pneumatic In-Line Magnets (PIM) – These designs are for use in dilute phase pneumatic conveying systems (up to 15psi). They can be installed easily with optional factory-supplied compression couplings and work best in horizontal runs with the plate magnet down to take advantage of material stratification;

Another design of In-Line Magnet is the Center-Flow, although the magnetic field is generated in a Cone configuration instead of a Plate.  The Magnetic Cone is positioned in the center of the housing, allowing the powder to flow in the space left between the housing.  Center-Flow In-Line Magnetic Separators are commonly used in dilute-phase pneumatic conveying lines up to 15psi.

To achieve optimum contact with the product flow, a conical magnet is suspended in the center-line of the housing.  This tapered, exposed-pole cartridge has a stainless steel “nose cone” to direct the flow of materials around the magnet.  The tapered poles of the cone magnet allow ferrous fines to collect out of the direct air stream.  Additionally, the trailing end of the magnet is an active magnetic pole and holds any tramp metal that is swept down the cone.

Both types of In-Line Magnet are designed with clamps and doors to enable easy access for cleaning.

drumIn specific applications, a high strength Neodymium Drum Magnet will enable the best level of separation.  The Drum Magnet is gravity-fed, usually via a Vibratory Feeder.  The Drum Magnet has a stationary high-strength magnetic arc positioned inside a rotating outer shell.  When material flows onto the drum magnet, the magnetic field projected by the stationary magnetic assembly inside the shell captures fine iron and holds it securely to the drum’s stainless steel surface.  With contaminants removed, the good product falls freely to a discharge point.  As the drum rotates, the captured fine iron travels along the drum surface and out of the magnetic field, where it is discharged.

There are various magnetic field configurations possible, but the most suitable for removing iron from powder is one that produces a Radial Magnetic Field.  This ensures that once captured, the fine iron does not leave the Drum surface until it moves out of the magnetic field.

Processing powder on a Drum Magnet presents more difficulties that other designs of Magnetic Separators.  Firstly, it is recommended that the Vibratory Feeder has an air bed to produce a consistent feed of powder.  Standard Vibratory Feeders may deliver powder in clumps, significantly affecting the separation performance.

Secondly, the shell of the Drum Magnet should be rotated at high speeds.  This will result in some of the powder pluming, and this can be minimized by keeping the distance between the end of the Vibratory Feeder Tray and the rotating surface of the Drum Magnet to a minimum.

The high rotation speed of the Drum Magnet significantly reduces the amount of product lost to the magnetics.  This is because there is less material on the surface of the Drum at any one time, reducing the chance of entrapment.

The use of Drum Magnets operating at high rotational speeds has been very successful in removing fine iron from abrasives, refractories, and other applications where the material has a high specific gravity.

Ensuring Powder is Metal-Free

As the demand for finer and purer powders increases, so does the need to remove even the finest iron.  Understanding the properties and behavior of the powder is vitally important when considering the optimum method of fine iron separation.  Often the ultimate solution is a series of Magnetic Separators and Metal Detectors located at strategic points within the process.

For further information on removing fine metal contamination from powders with Magnetic Separators and Metal Detectors please contact us on: