Metal Detectors Detecting More Than Treasure

Technology Keeping Waste Metal-Free

The BBC television series Detectorists has significantly increased the public’s awareness of metal detectors, but many people remain unaware of their importance in the recycling of waste materials.

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Although the size and design of metal detector used in the recycling industry may be different to those used by the enthusiasts on the television show, the basic concept is the same.  When an electric current is passed through the coil of a metal detector, it creates a magnetic field.  If a piece of electrically conductive metal is close to the coil, eddy currents will be induced in the metal, and this produces a magnetic field of its own.  A separate control recognises that the new magnetic field has changed the metal detector’s magnetic field and identifies that there is metal present.

Metal Detectors are becoming increasingly important in the recycling industry.  Magnetic Separators and Eddy Current Separators are widely used to remove liberated ferrous, non-ferrous and even some stainless-steel metals, but are unable to separate metals that are imbedded in material or are unresponsive to these types of metal separators.

This is particularly important in recycling operations where the waste material is large in size and needs to be shredded or granulated.  A common location for the Metal Detector is on the conveyor prior to size reduction, where it identifies the presence of any metal that may damage the shredder or granulator.  The effect of metal damage can be costly in terms of repair and also downtime.  Typical waste materials include plastic, wood, and demolition waste.

There are primarily two different types of Metal Detector suitable for detecting metal in such conveyed material.  The Underbelt Conveyor Metal Detector is ideal when handling larger materials of variable shapes and sizes and the aim is to detect larger metal.  Two different coil designs mean that the Metal Detector is suitable for belt widths from 100mm to 1200mm.  This design of Metal Detector identifies and then stops the conveyor belt.  Operators then locate and manually remove the metal contamination.

The second type of Metal Detector surrounds the conveyor belt.  This increases the detection sensitivity and is also needed when there is a deeper burden depth on the conveyor.  There are various coil configurations, such as the QDC, QTA, and TN77, and the selection is based upon each application.

Once the waste has passed through the process of size reduction and separation, Metal Detectors are commonly used to check that metal is not present in the final product.  In some applications, the material will still be conveyed and so previously mentioned designs are used.  However, in applications where the particles are now significantly smaller different designs of Metal Detector are required.

Bunting Metal Separation System Recapture Plastics-0424In plastic recycling plants, Free Fall Metal Detectors such as the quickTRON 03R not only detect but also reject metal contamination.   Gravity free-fall style metal separators are specifically designed to isolate and separate any contaminated material moving in the product flow.  They automatically detect, pick up and reject both ferrous and non-ferrous from the product flow without any interruption to the line process.

As each application can be unique, selecting the optimum Metal Detector for an application is best achieved by conducting a site visit to understand the process and the objective.

Bunting Magnetics is one of the world’s leading suppliers of Magnetic Separators and Metal Detectors which includes the Master Magnets and Metal Detection branded range of equipment.

For further information on metal separation equipment designed for detecting and 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

Getting Metal Out of Beer

Ideal Locations for Magnetic Separators and Metal Detectors in a Brewery

Thankfully, it is very unlikely that you will ever find a piece of metal in your glass of beer.  However, when tramp metal in the form of screws and nails is accidentally introduced during the brewing process, it damages processing equipment and can even affect the taste of the beer.  In this article we look at the best methods of ensuring that the brewing process is unaffected by tramp metal.

Bunting_Magnetics_Europe_Brewery_Plant

As with any food process, there are many locations where metal can be inadvertently introduced.  With raw materials being collected from the fields and then transported to the brewery in large trucks, contamination by metal and other materials is unavoidable.

Here we look at a typical brewery and identify where Magnetic Separators and Metal Detectors could be located to remove any metal contamination.

Location 1 – Malt In-feed Line

When the malt is delivered by truck or rail, it is commonly pneumatically transported into storage silos.  A Pneumatic In-Line Magnet and/or Metal Detector would ensure that any tramp metal in the raw material feed is removed prior to storage.

Bunting Magnetics In Line Magnet-2

A Pneumatic In-Line Magnet is designed to easily fit into a pipeline without causing any obstruction.  It has a magnetically strong Plate Magnet mounted on one side which attracts and holds any ferrous metal.  This is then manually removed on a regular frequency.

The Metal Detector identifies and then ejects any remaining metal contamination, both ferrous and non-ferrous.  As most metal contamination at this stage is ferrous, installing the Metal Detector after the In-Line Magnet reduces the amount of metal detection rejects and thus reduces the loss of product.

Location 2 – Prior to Milling

cartridge_magnetsGrate Magnets are commonly positioned in or above the in-feed hopper to the mill, especially if there has been no previous metal separation or detection.  A Grate Magnet is a series of Tube Magnets designed in a grid to fit inside a hopper.  For maximum protection of the mill, the Grate Magnet uses a set of high magnetic strength Rare Earth Neodymium Tube Magnets.  Such protection ensures that no tramp metal enters the mill where it can cause serious and expensive damage.

Location 3 – Hot Water Feed to Mash Tun

Bunting Magnetic Liquid TrapWater is a common source of metal contamination in food processing plants and is also the one in-feed material that is often overlooked.  The nature of water means that rust is common and a simple Magnetic Liquid Trap is used to attract and capture any rogue ferrous metal, even in a very fine form.  A Magnetic Liquid Trap is designed to be easily introduced into a pipeline, with flanges or any other connector.  Inside the body, high strength Rare Earth Neodymium Tube Magnets project down into the material flow, attracting and capturing any ferrous or weakly magnetic materials.  The Tube Magnets are removed from the process and manually cleaned.

Location 4 – Between Mash Tun, Lauter Tun and Brew Kettle

Magnetic Liquid Traps could also be located between the Mash Tun, Lauter Tun and Brew Kettle, especially is there has been limited protection earlier in the process.

Location 5 – Hops In-feed Line

Protection is important whenever raw materials are introduced into the process and Grate Magnets and a Quicktron Metal Detector will ensure that hops entering the brew kettle are metal-free.  This design of Metal Detector is for free-fall material.  As the material enters the metal detector, any metal is detected and then automatically rejected.  The Grate Magnet reduces the amount of material lost during the rejection process by removing any ferrous metal.

Location 6 – Between Brew Kettle and Whirlpool/Settling Tank

After the brew kettle , a Magnetic Liquid Trap, with special Neodymium magnets designed to withstand high temperatures, will provide final protection prior to settling.

Location 7 – Yeast In-feed Line

As on the hops in-feed line, a combination of a Grate Magnet and Quicktron Metal Detector will ensure that any metal does not enter the process.

Location 8 – Between Conditioning Tank and Filter

To protect the filter, a Magnetic Liquid Trap is often installed after the conditioning tank.

Location 9 – Prior to Bottling

p-TRON-GM-V2As in many food processing plants, it is good practice to install a Metal Detector (in this case a P-Tron) at the final stage of the process.  This provides a final stage of protection to ensure that any metal introduced into the process from damaged processing equipment such as the filter or in the pipes is detected and removed.

This is a typical example of a Brewing Operation.  However, each plant is unique and often a site visit is required to assess and recommend the best ways to ensure a metal-free end product.

For further information on removing Metal during the brewing process using Magnetic Separators and Metal Detectors, please contact the Bunting technical sales team on:

Other Food Plant Reviews include:

Bunting_Magnetics_Europe_Brewery_Plant

 

 

 

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:

Getting Metal Out of Plastic on the Bunting Stand at Interplas 2017

Bunting Magnetics Magnetic Separators and Metal Detectors at UK Plastics Show

The latest Magnetic Separation and Metal Detection technology will be on display on the Bunting Magnetics Europe stand (Hall 4, Stand H11) at Interplas 2017 (NEC, Birmingham, UK, 26th – 28th September 2017).

Bunting FFS Magnet-0064A
Bunting FF Drawer Grate Magnet

Bunting Magnetics is one of the world’s leading suppliers of Magnetic Separators and Metal Detectors.  The European manufacturing headquarters are based in Berkhamsted in Hertfordshire, UK and they have an extensive overseas network of distributors and marketing agents.  In January 2017, the company acquired Master Magnets, significantly expanding their range of Magnetic Separators and Metal Detectors.

“Interplas is the number one exhibition for the plastics sector in the UK,” said Dave Hills, Bunting’s Head of Sales, “and the show gives us a great opportunity to meet many existing and potentially new customers.”

Bunting Magnetics has a strong global relationship with the plastics sector.  Many of their Magnetic Separators have been designed specifically for use in the manufacture and recycling of plastics and plastic products.

The Magnetic Separators and Metal Detectors on the Bunting stand at Interplas are designed to capture, identify and remove metal contamination.  The presence of rogue metal damages processing equipment and affects the end-product quality and reject rates.

Bunting BPI-6151

The FF Drawer Grate Magnet is specifically designed for removing magnetically-susceptible particles from plastic.  The standard model has 2 banks of Neodymium Rare Earth Tube Magnets mounted inside a sealed housing.  Other variations are available including a low profile design for positioning underneath large hoppers and silos. Magnetic Separators with Neodymium Rare Earth Magnets remove even the smallest magnetically-susceptible particles.  On the stand will be examples of extremely strong Magnetic Grates, Plate Magnets, Tube Magnets, and the industry-standard FF Drawer Grate Magnet.  Visitors will be invited to test the magnetic strength for themselves.

Bunting Magnetics Europe at RWM16“This combination [FF Drawer Grate Magnet and the quickTRON Metal Detector] offers the best method of removing metal from free-falling materials,” explained Dave Hills.  “The Magnetic Separator captures and holds any magnetically attracted metals such as steel screws, bolts, steel slithers from worn equipment, and even work-hardened stainless steel.  This always proves to be the bulk of the metal contamination.For a complete metal separation solution, the FF Drawer Grate Magnet is fitted above a quickTRON Metal Detector.  The Metal Detector then identifies and rejects any non-ferrous metals.

“Any remaining metal will be identified as it passes through the Metal Detector and then ejected.  The cleansed plastic can then proceed safety into the next stage of the process, whether than is to the extruder or granulator.”

A working, production-sized model of the combined FF Drawer Grate Magnet and quickTRON Metal Detector will be on the Bunting stand at Interplas.  Regular demonstrations will enable visitors to witness the capabilities of the complete metal separation system.

p-TRON-GM-V2
pTRON Metal Detector

A range of pTRON Metal Detectors designed for use in Pneumatic transportation lines will also be on display on the Bunting stand.

With the acquisition of Master Magnets, Bunting also has an extensive range of Magnetic Separators and Eddy Current Separators for the recycling sector.

“The combined experience of Bunting and Master Magnets means that we have a solution for most metal separation problems.  The Master Magnets Eddy Current Separator is an industry standard and is used to remove non-ferrous metals from plastics in recycling operations across the world,” said Dave Hills.

For further information on the Magnetic Separators and Metal Detectors that will be on show at the Interplas 2017 exhibition, please contact us on:

Export Success at FIP Solution Plastique Exhibition

Bunting Magnetics Support BMS France at Plastics Show in France

Dave Hills, Bunting Europe’s Head of Sales, was on the stand of local distributor, BMS France for the duration of the major annual international plastics exhibition, FIP Solution Plastique, held in Lyon, France between 13th and 16th June 2017.  Dave gave us this report:

“Last week [13th to 16th June] it was hot and humid in Lyon.  And it was debatable whether the air conditioning in the exhibition centre was actually working.  However, the turnout for the show was fantastic.

FIP Solution Plastique is the number 1 show for the plastics sector in France.  There was a technically and globally diverse group of exhibitors present, all specialising in working in the plastics industry.

We were present to support our local distributor BMS France.  Being on the stand gave me the opportunity to develop relationships with the BMS team, deliver some product training, and also learn about the plastics market in France.  I also had the opportunity to meet the BMS Spain team, based in Barcelona.

It was also good to meet and talk with other equipment suppliers, many of who had equipment on display at the show.  It was interesting to hear their feedback on present market conditions.  We find exports visits such as this invaluable.

Bunting_FIP_Solution_Plastique_France-1987

Along with our Metal Detectors and Magnetic Separators, BMS had a wide range of equipment on the stand.  There were 3 operating Boy Injection Moulding Machines on one stand and a Woojin Injection Moulding Machine on a 2nd stand.

There were also 5 Wanner Granulators, and Pixargus had a live demonstration of their unique surface inspection and dimension measurement system.

The extensive range of products and the interactive nature of the BMS France stand made it one of the busiest at the show.

Bunting_FIP_Solutions_Plastique_17-1985

It was interesting to think that all of the aforementioned equipment relies on the plastic pellets and raw materials being metal-free.  And getting metal out of plastic is our speciality.

BMS France was able to talk to visitors about a complete solution, with demonstrations of the quickTRON 03R Metal Detector and FF Drawer Filter Magnet removing both ferrous and non-ferrous metals.

Being in France also gave me an opportunity to hear people’s thoughts about BREXIT.  Unlike some other European countries that I have visited since the referendum, people in France have a very negative opinion about the UK leaving the EU.  In fact, many people asked whether the decision could be overturned.  This just highlights the importance of a negotiated exit that involves free trade.

However, the atmosphere at the exhibition was very positive.  Indeed, BMS France sold 2 Injection Moulding Machines at the show, which was fantastic.  And both will be protected by Bunting Metal Detectors and Magnetic Separators.

An excellent show and we will be back in 2018.”

For further details on the Bunting range of Magnetic Separators and Metal Detectors used to remove metal from virgin and recycled plastic, please contact our technical sales team on:

Bunting_FIP_Solution_Plastique_France--2

Cases of Metal Found In Food

A Food Safety Nightmare

To mark the start of the UK’s Food Safety Week (19th – 23rd June 2017), we are looking at recent cases where there has been an issue with food safety with specific reference to metal contamination.

Metal_Physical_Hazard

Metal contamination is commonly found in foods as they are being processed.  Metal can be introduced at a number of stages including:

  • Originating in the raw food product prior to arrival at the processing plant;
  • During transportation of the foodstuffs to the processing plant;
  • In the process from process machinery wear or failure;
  • Accidentally by workers or during maintenance;

In the vast majortity of food processing plants, there will be a series of Magnetic Separators and Metal Detector to remove and identify any metal contamination prior to the finished food product leaving the factory.

However, if the Magnetic Separator or Metal Detector is not operating to the optimum efficiency, or if there are no systems to remove metal installed, then metal end up in the food product being purchased by the consumer.

Recent Metal Found In Food Cases

These are some recent cases where metal has been found in food.

  1. In May 2017, William Santus & Co announced that Uncle Joe’s Liquorice & Aniseed Extra Strong Mints (35g tins) were recalled because there were fears that the sweets may contain small pieces of metal;
  2. UK supermarket Tesco faced a ‘metal-in-food’ safety warning in March 2017 when there were fears that the vegetarian product, Quorn Meat Free Mince (300g pack), was contaminated with small bits of metal;
  3. Lotus Bakeries UK Ltd recalled Lotus Biscoff Crunchy Biscuit Spread because the product may contain small pieces of metal.  This affected most of the supermarkets in the UK in March 2017;
  4. Metal Found In Morrisons Green BeansThe food company OK Food Inc (Oklahoma, USA) recalled more than 466 tons of breaded chicken because of possible metal in the food in March 2017;
  5. In the USA, Blue Buffalo dog food had to be recalled in March 2017 after a Lakeland woman reported that she had found metal.
  6. UK supermarket Morrisons was hit by a food safety scare in April 2017, when metal wire was found in green beans;

In all cases, the cost of recalling the product was significant, but for many it was not as high as the damage to the company’s reputation.

Other Food Safety reports relating to Metal-in-Food include:

For more information on preventing Metal Contamination Food Safety Scares, 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

Getting Metal Out of Processed Vegetables

Ideal Locations for Magnetic Separators and Metal Detectors in a Vegetable Processing Plant

Processed vegetables are a vital part of the food chain.  Tens of thousands of bags of pre-cut carrots and freshly prepared kale are bought in supermarkets daily.  Frozen vegetables have been very popular since Clarence Birdseye invented the quick freezing method in 1924.  Also,  often-unnoticed processed vegetables are present in many everyday food items such as tinned soup, baby food, sauces, and ready-made meals.

However, processing vegetables takes a great deal of care and attention as the products are often delicate and can be easily damaged.

BUNT-2286 4 8.5x11 plants

As with all processed foods, there is always the risk of metal contamination.  Metal can be introduced at various stages in the process.  The design and positioning of the Magnetic Separator or Metal Detector has to also respect the delicate nature of the product.

Untreated Vegetables Feedstock

During the collection and transportation of the raw vegetables, there is always a high risk of metal contamination.  This can be remove using a Plate Magnet.  To avoid contact with the vegetables and eliminate the risk of damage, the Plate Magnet is suspended above the incline conveyor feeding the washer.  Metal is attracted up onto the face of the Magnet and held until cleaned.  This is ideal to remove larger metal items such as screws and nails.

Post Washing

The vegetables washing process frees dirt and other detritus including metal particles.  Prior to the washed vegetables being fed into a drier, a Permanent Magnetic Pulley, replacing the standard head pulley of a conveyor, attracts and automatically removes any free metal before entering the drier.  Again, there is no physical content between the Magnetic Separator and the vegetables.  After drying, the vegetables are fed into a dicing machine.

Prior to Dicing

Plate Magnet Tapered Step-9545
Plate Magnet Tapered Step

The blades on a dicing machine are delicate and expensive.  Metal contamination can cause significant damage.  To ensure that no metal is present, the dried vegetables are fed over the surface of a Plate Magnet.  This enables higher levels of separation that when the Plate Magnet is suspended as the material is passing closer to the area of maximum magnetic strength.  Any potential damage to the vegetables as they flow over the surface of the Plate Magnet is limited.  Metal is captured and then held under the lip of a tapered step on the surface of the Magnet.

Undersized Vegetables

Smaller sized diced vegetables are often taken on a different route.  They can be mixed with water, for ease of transportation, before being reintroduced into the process.  Immediately after dicing, the smaller particles fall through a Quicktron Metal Detector to remove any small ferrous and non-ferrous metals (including any broken blades from the dicer).  Water from the external source is passed through a Magnetic Liquid Filter Magnet to ensure that any rust or other ferrous metal contamination is not introduced into the process.  The Undersized Vegetables are mixed with the water and then re-introduced into the process.

Final Packed Product

Metron 05C Metal Detector
Metron Metal Detector

The final stage of weighing and packing includes 3 steps of Metal Removal and Detection.  Prior to weighing, the processed vegetables are passed over the surface of a Plate Magnet to ensure that all ferrous metal contamination has been removed.  After weighing, the vegetables fall under gravity through a Quicktron Metal Detector where any non-ferrous metals are removed.  Finally, after packing, the finished packed batch of processed vegetables are passed through a tunnel-type Metron C02 Metal Detector as a final check prior to shipment.

This is a typical example of a Vegetable Processing Plant.  However, each plant is unique and often a site visit is required to assess and recommend the best ways to ensure a metal-free end product.

For further information on removing Metal from Processed Vegetables using Magnetic Separators and Metal Detectors, please contact the Bunting technical sales team on:

Phone: +44 (0) 1442 875081
Fax: +44 (0) 1442 875009
Email: sales@buntingeurope.com
Web: http://www.buntingeurope.com

Other Food Plant Reviews include:

Morrisons Hit by Metal In Green Beans Scare

The Nightmare of Metal Contaminated Food

On Friday 21st April 2017, UK supermarket giant Morrisons was faced with a ‘Metal In Food’ health scare.  As reported by the BBC and others, two customers found the metal in packets of the vegetables in Manchester and Glasgow stores.

The Food Standards Agency issued a warning for the affected products, which are the supermarket’s 170g bags of the beans with display until dates of 22 April, 23 April and 24 April.

Supermarket WarsUnfortunately, this latest ‘Metal In Food’ scare is not unusual.  Even though a spokeswoman for Morrisons said an investigation was under way, the ramifications of this latest food health scare are considerable.  Not only is there the cost of recalling and refunding the product, but the announcement will affect consumer confidence.  As the UK supermarket war prevails, customers are very quick to switch allegiance and concerns about ‘Metal In Food’ might be enough for them to purchase their food at competitor’s stores.

For Morrisons, the question is how did such a food health scare occur.  Although it is unclear where these green beans were sourced, food is sourced globally.  However, the levels of control in different countries is variable.  A plant in Egypt may have different outlook than a UK producer with regards to health safety.  There are strict regulations in Europe that often do not apply outside our borders.  These regulations protect the consumer, but often mean higher production costs.

However, as the supermarket war continues, the pressure to find lower cost food sources intensifies.

And therein lies the conundrum.

If Morrisons and other supermarkets are going to increase their reliance on food supplied from outside of Western Europe, then will they dictate the food safety standards?  Some food suppliers such as M&S already instruct their suppliers on how to prevent ‘Metal In Food’ safety scares, providing advice on the installation of both Magnetic Separators and Metal Detectors.   They also regularly inspect their suppliers plants.

There is a significant cost involved in this proactive and involved approach, which may be too much for some supermarkets to accept.

Metron 05C Metal Detector on conveyorAnother option is to have all products checked at a warehouse prior to despatch.  The green beans in question could have passed through a tunnel-type Metal Detector which would have detected the metal.  However, such an initiative would increase processing time, delay despatches, and in crease costs (i.e. personnel).

This latest ‘Metal In Food’ scare follows many others including Ben & Jerry’s Ice Cream, metal in bread at Sainsbury, metal found in food processing plants in the USA.  And it will not be the last.  The big question is what needs to be done to regain consumer confidence and ensure that food products on supermarket shelves are ‘Metal-Free’.

The other Food Safety reports relating to Metal-in-Food include:

For more information on preventing Metal Contamination Food Safety Scares, please contact the Bunting team on:

Phone:  +44 (0) 1442 875081

Email:  sales@buntingeurope.com

Via the website

 

 

Getting Metal Out of Spices

Ideal Locations for Magnetic Separators and Metal Detectors in a Spice Processing Plant

Most households have a collection of spices in one of their kitchen cupboards.  Adding spices to food when cooking is now a common practice, but how are they processed and prepared?

Most spices are grown in the tropical regions of the world, with some thriving in the cool misty highlands. Many of the seed spices come from more temperate areas, such as coriander seed, which is grown in Northern India, Africa and the wheat producing areas of South Australia and Western New South Wales.

BUNT-2910 Perfect Plants 5

The nature of the location and how the spices are collected mean that there is a high risk of metal contamination.  Most spice plants use a series of Magnetic Separators and Metal Detectors to remove and detect any problematic metal.  Indeed, many UK supermarkets and food retailers (eg M & S) have strict guidelines on the use of Metal Removal equipment.

The plant shown in the flowsheet is a generalisation of a typical spice producing operation and highlights suitable locations for both Magnetic Separators and Metal Detectors.

On Delivery

Ideally, it is always best to remove metal before it enters the process.  The metal tends to be larger in size and easier to separate.  At this early stage, the delivered spices can be passed over a High Intensity Rare Earth Drum Magnet.  This automatically removes magnetically susceptible metal prior to the spices moving on to storage.

Prior to Processing

Metal damages processing equipment and so it is always best practice to ensure protection by installing a Magnetic Separator.  The spices can be passed over a simple Plate Magnet prior to grinding, protecting the grinding plates from damage.Plate Magnet Bunting Magnetics-9805

After Grinding

The process of grinding may liberate entrapped metal and may introduce fine iron into the process.  A Plate Housing Magnet followed by a Quicktron Metal Detector removes any metal.

At this stage, the spice may be sent directly to bagging.  There are several types of Magnetic Separator that are often used to ensure a metal-free product including a Pneumatic In-Line Magnet on the pneumatic line, and a Grate Magnet or Plate Housing Magnet just prior to packing.  A FS Metal Detector can also be used to remove any non-magnetic contamination.

After MixingBunting Magnetics In Line Magnet-2

Once the spices are mixed into a blend, they can be passed through a Centre Flow In-Line Magnet and Quicktron Metal Detector prior to storage in drums or containers.  Prior to the spices being bottled, a final stage of Magnetic Separation is often used.  This is commonly a form of Grate Magnet followed by a Quicktron Metal Detector.  The final check on the bottled spice is often undertaken using a conveyor-type Metron C Metal Detector.  The bottles are then packed ready for despatch.

The multiple stages of Metal Separation may appear excessive, but are required due to the nature of the process.  Metal in a wide variety of forms can be introduced at any stage in the process, especially after grinding and mixing.  Installing different designs of Magnetic Separator and Metal Detector at different points in the process will ensure the best protection against metal contamination.

For further information on removing Metal from a Spice processing plant using Magnetic Separators and Metal Detectors, please contact the Bunting technical sales team on:

Phone: +44 (0) 1442 875081
Fax: +44 (0) 1442 875009
Email: sales@buntingeurope.com
Web: http://www.buntingeurope.com

Other Food Plant Reviews include:

 

 

 

 

 

Ingesting Metal Fragments Can Cause Injury states the FDA

Solving the Problem of Metal Contamination in Food

In a 10 page document, the US Food and Drug Administration (FDA) declares that metal fragments in food may cause dental damage, lacerations of the mouth or throat, or laceration or perforation of the intestine.  They do not mention the untold damage to a company’s reputation and the subsequent financial damages.  Only last month (February 2017), PetSmart in the USA recalled dog food over a potential metal choking hazard.

It is nearly impossible to stop metal fragments entering a process line.  Processing equipment will wear, especially with metal-to-metal contact, and there will be equipment failures (e.g. valves, screens, conveyors, etc.).  Once that fact is accepted, then a solution to the problem of removing and detecting that metal before it reaches the consumer can be found.

Tube Cartridge Magnets Bunting Magnetics-7

Several methods of metal removal are employed of which Magnetic Separation and Metal Detection are the most common.  The effectiveness of this equipment is dependent on the nature of the product, the location of installation and the maintenance.  Well-planned and executed maintenance, especially with planned Magnetic Separator cleaning schedules, will ensure that metal separation levels are maintained for the long term.

Magnetic SeparatorsBunting Magnetics In Line Magnet-16

Magnetic Separation is commonly used to remove metal from liquids and free flowing solids or powders.  By positioning the Magnetic Separator in the process (i.e. inside a pipeline or chute), magnetically susceptible metal (such as ferrous metal and abraded or work hardened stainless steel) is attracted by the magnetic field and then held on the surface of the magnet.  There are many different designs of Magnetic Separator and strengths of magnet to suit different applications and locations.

Quicktron05A_Sodium Bicarbonate 2Metal Detectors

Metal Detection can also be used as part of a separator, whereby metal is detected and then rejected immediately.  This is often used in free fall locations, but can result in high losses of product.  More commonly, Metal Detection is installed at the end of the process either just before or/and after the product has been packaged and packed.

Guidance to Address Metal Contamination

The FDA document is very helpful and even outlines ways to determine if the potential metal contamination hazard is significant.  Continuous monitoring and verification form key parts of the metal contamination management plan.  Regular and planned checks on the Magnetic Separators and Metal Detectors are vitally important to ensure that the level of separation and detection performance is maintained over time.

The US Food and Drug Administration (FDA) give specific guidance on the issue of metal inclusion or contamination on their website. 

Typical Food Process Line

To assist food manufacturers assess the optimum ways to address metal contamination, we have produced a series of Flow Sheets.  These show typical locations for both Magnetic Separators and Metal Detectors.

For more information or a metal contamination site survey by our trained sales engineers, please contact our team on:

Phone:  01442 875081

Email:  sales@buntingeurope.com

Via the website