A third-party auditor just showed up at your food processing facility. How confident are you in the performance of your magnetic separation equipment? Are the magnets at your critical control points still performing at full strength and how would you know? While magnets generally have a long and effective life, certain food products and processes can permanently damage them, resulting in loss of strength. If your operation has any of the three process-related risk factors for magnets, learn how to reduce your compliance and safety risks, as well as protect your equipment from damage. Dr. John Ormerod, Magnet Applications Senior Technical Advisor at Bunting Magnetics Co., explains how to improve magnet effectiveness for Food Processors and the benefits of magnetic pull test kits.
Bunting Magnetic Can Conveyors Offer Innovative Solutions for the Food Industry
Magnetic can conveyors have been a core element of food manufacturing operations — elevating cans to all floors and operations of a plant — for decades. Though the function of magnetic can conveyors is straightforward, there are specific criteria, and nuances within those criteria, to consider when selecting and customizing the right magnetic can conveyor, and choosing the right vendor, for your facility. Donald Suderman, Material Handling Product Manager for Bunting Magnetics Co., explains how to choose the right magnetic can conveyor for your food manufacturing operation.
You just sat down to enjoy your Saturday breakfast – hot coffee, orange juice, toast, hash browns, sausage, and an egg-white omelet. Everything seems perfect until you take a bite of sausage. Something doesn’t seem right. Instead of a burst of smoky flavor, you pull a metal fragment out of your mouth. You check the rest of your meal for metal scraps. You end up throwing away the rest of your breakfast, worried about how much metal you may have eaten without noticing. Finding metal contaminants in your food isn’t only “annoying” and unappetizing. It also poses serious risks to your health, especially if ingested. This unfortunate scenario recently became a reality for a national breakfast food company, which resulted in a massive product recall. There is something that could’ve prevented this public relations nightmare – accurate and dependable metal detection! Metal detectors sense the presence of ferrous, nonferrous, and stainless metals in a process flow, or as a packaged item, and allows you to remove the contaminated product.
Bunting Magnetics Co. Offers Metal Detection Solutions for the Food Industry that Keep Products Safe for Consumers
In efforts of damage control, the breakfast food company tried hard to protect the brand, and attempted to assure customers of their commitment to safety. However, this incident will likely have a lingering impact on the company’s reputation. This all could have been avoided if they had been using the proper magnetic and metal detection equipment on their processing line. Metal is the most common foreign material found in food products. This is why it’s so important for companies to detect and remove these hazardous contaminants before the product is packed and shipped. When contaminated food reaches the open market, it can have devastating consequences for both the company and their customers.
Using the right magnetic applications and metal detectors (along with regular testing and maintenance) is the only way to keep food products pure and safe for consumers. Bunting metal detectors are used in food plants to ensure the purity of your product, while protecting your valuable machinery from damage. Having metal detection applications that can handle both fresh and frozen meats is crucial to the success of businesses in the food industry. Our Gravity Free-Fall Style Metal Detectors are perfect for applications in either horizontal or vertical installations where space is limited. Tunnel Style Metal Detectors are custom-made for the unique needs of your application. They are used for the final inspection before a product ships to the customer. Triple Frequency Controls detect a packaged food product in three different conditions, giving you the most accurate readings for the best product results possible.
For more information about which metal detection products are best for your application, please contact Bunting Magnetics Co. to speak with a sales representative. We look forward to hearing from you and discussing how our metal detection products can help your business succeed!
Citrus juice producers around the world are finding a better way of keeping orange juice free from harmful metal contaminants. In the last 18 months, Bunting Magnetics Co. has manufactured and sold 15 of our magnetic liquid traps to citrus producers in Spain. The progress that Bunting Europe is making in this market is exciting. It’s a testament to the innovative line of magnetic separation products that Bunting Magnetics Co. is known for throughout the world. Our newest product in North America, the Corrosive-Resistant Liquid Trap, was recently showcased in October 2018 at Pack Expo International in Chicago. This magnetic liquid trap is especially made to handle acidic foods, and remove fine iron from citrus juices. The Corrosive-Resistant Magnetic Liquid Trap has a much higher resistance to levels of acidity, which means it’s far less susceptible to damage than other applications. Keeping orange juice safe to drink and protecting your valuable investment? That’s what we call a “win-win” situation.
The Bunting Corrosive-Resistant Magnetic Liquid Trap is Your Solution for Products with High Acidity
How Do Metal Contaminants Enter Citrus Products?
Fine irons and stainless steel are common contaminants found in food processes. While it’s sometimes difficult to determine the source of the contamination, there are several ways that these hazardous metals can enter the system:
Harvest –Dirt often has a magnetic constituent, which is transferred to the fruit’s surface during harvest.
Transportation – Despite the use of plastic containers to store the fruit, the transport itself can spread metal contamination through rust, metal, dust, and dirt.
Processing – When juice is extracted from oranges or grapefruits, there are several stages where the fruit is sliced and compressed. Metal contamination can occur when this equipment is worn down.
Getting Rid of Metal Contaminants
High-strength magnets are needed to remove fine metal contamination from juices and liquids. Neodymium Rare Earth magnets are used in Bunting Magnetic Liquid Traps to capture magnetic debris, such as work-hardened 300 series stainless-steel fragments. Maximum contact is made between the juices and the magnetic fields by forcing liquids through a tightly spaced grid of magnets. The powerful rare earth magnet design is held firmly on the surface of the tube magnets to magnetically extract ferrous contamination from the liquid flow.
However, fruit juices contain very high levels of acidity, which can corrode and damage equipment. “Over time, acidic foods and cleaning solutions cause pitting and other damage to the equipment. This means downtime during peak production in order to replace parts,” explains Rod Henricks, Director of Sales.
Processors in the produce industry needed a stronger, safer, longer-lasting liquid trap that didn’t require constant replacements. This is why Bunting Magnetics Co. created the Corrosive-Resistant Liquid Trap. It has a much higher resistance to chloride pitting, crevice, and stress-cracking corrosion. The CR-MLT is better equipped to handle highly acidic foods such as tomato paste, ketchup, vinegar-based products, and citrus products like orange juice. The Corrosive-Resistant Liquid Trap utilizes high-intensity neodymium 45SH magnets that are temperature-compensated, in order to capture metal contamination in orange juice and other citrus liquids.
For more information about which magnetic liquid traps are best for your application, please contact Bunting Magnetics Co. to speak with a sales representative. We look forward to discussing the unique needs of your business, and helping you find a magnetic separation product that helps you succeed!
What makes food safe to eat? How are recycling companies actually able to “recycle”? How are grains kept pure? How is processing equipment protected from damaging metals? How are millions of products kept safe for consumers all over the world? It has nothing to do with Superman leaping tall buildings. The answer to these important questions is simple – it’s because of magnetic separation!
Magnetic separation has changed the world, and is responsible for product and food safety standards that we sometimes take for granted. Thanks to the innovations of magnet applications, we are able to eat food and use products that are free of dangerous materials. Magnetic separation also protects your equipment from serious damage by keeping the line clear of hazardous metal scraps. Whether you’re in the Food, Dairy, Grain and Milling, Chemical, Plastics, Oil, Textile, Recycling, Powder and Bulk, Mining, or the Non-Woven industries, magnetic separation applications are crucial to the success of your business.
Through the use of magnets, you are able to separate hazardous metals from your product before it’s shipped to consumers. This is extremely important for a number of reasons. When tramp metals are found in product and food, it can result in potential lawsuits, product recall, negative press, and severe injury to customers. Fortunately, this can all be avoided by investing in the right magnetic separation applications. The magnet separator you choose will depend on the type of material being processed and the system you are running the material through. Each system and product is unique, which means there is no “one size fits all” solution when it comes to magnetic separation.
Bunting Magnetics Co. has nearly 60 years of experience helping customers find magnetic separation solutions that fit the unique needs of their applications.
Types of Magnet Materials
The type of magnet material you choose is determined by the density of the product, its flow rates, operating temperatures, and the types of ferrous contaminants you are trying to remove. Ceramic magnets are generally used for typical tramp iron separation, while alnico magnets are better suited for high operating temperatures.
Rare earth magnets are used when product densities and flow rates are high, and encounter weakly magnetic debris and grades of work-hardened steel. Types of rare earth magnets that are used for permanent magnetic separators include: Neodymium, Samarium Cobalt, and Ceramic Ferrite. Neodymium rare earth magnets are the strongest available, and are used to remove fine iron and stainless steel. Samarium cobalt magnets are smaller, slightly weaker, and can withstand higher temperatures. Ceramic ferrite magnets are lower strength, but produce deep magnetic fields. This makes them perfect for designs where the magnetic field needs to be projected at a distance.
Types of Magnetic Applications
There is a wide selection of magnetic separators that are used in the following industries: Recycling; Aggregate, Mining and Minerals; Grain and Milling; Food Production; Plastics; Non-Woven; and Powder and Bulk. Choosing the right magnetic separator will depend on the type of material being processed and the system you are running the material through.
Drawer Magnets are ideal for gravity flow applications and are used for easy-flowing, dry material. They are typically used in the Recycling, Food, Powder and Bulk, and Plastics industries to remove fine tramp metal contaminants. Drawer magnets are available in utility, food, and sanitary construction grades with multiple cleaning options and stainless steel housings.
Drum Magnets are used for a wide range of free-flowing bulk and granular materials in high-volume applications. They provide continuous removal of ferrous contaminants, and are used in the Plastics, Recycling, Grain and Milling, Powder and Bulk, and Aggregate, Mining and Minerals industries.
Plate Magnets remove hazardous materials from powdery, moist, lumpy and abrasive products, as well as from large debris that might choke, bridge, or cause rapid wear in cartridge-based separators. Ideal for gravity free-fall applications, plate magnets can be easily installed in chutes to remove ferrous fines and large pieces of tramp iron. Plate magnets can also be installed above or below conveyor drive pulleys to capture contaminants as materials drop from open belts. They are used for handling more abrasive products, and are often used in the Plastics, Recycling, Food, Grain and Milling, and Powder and Bulk industries.
In-Line Magnets are designed for unobstructed product flow. They are usually equipped with rare earth magnets and are best used for products with slightly clumpy flow. In-line magnets are typically used in the Plastics, Recycling, Food, Grain and Milling, and Powder and Bulk industries.
Magnetic Liquid Traps remove ferrous tramp metals from liquid processing and conveying lines. They are often used in the Food, Grain and Milling, and Powder and Bulk industries, and provide protection against product contamination. Magnetic liquid traps can handle acidic food products, and remove the smallest ferrous particles from liquids with a higher viscosity.
Hump Magnets are used for high-volume product flow in the Food, Grain and Milling, Powder and Bulk, and Non-Woven industries. They increase protection against entrapped ferrous materials, while helping prevent build-up and bridging of larger products.
Grate Magnets are used in applications for the Plastics, Food, Grain and Milling, and Powder and Bulk industries. They can be installed in hoppers, pits, chutes, housings, and bins to remove tramp metals from larger flowing materials.
Wedge Magnets are installed in narrow, vertical, or steeply inclined chutes in gravity flow applications. They protect pellet mills and other equipment from damage caused by tramp metals. Wedge magnets are used in the Grain and Milling industry to process particulate or semi-solid materials.
For more information about which magnetic separators are best for your application, please contact Bunting Magnetics Co. to speak with a sales representative. We look forward to hearing from you and discussing how our magnetic separation products can help your business succeed!
The first thing you see after walking through the doors of the Sensors Midwest 2018 Expo is the BuyMagnets.com booth. We’re pretty hard to miss with the prime location right as you enter the hall. Our booth #400 has N42 and N52 magnets on display, where visitors learn how they can help their applications. BuyMagnets.com offers the largest selection of permanent and industrial magnet equipment in the industry. Our online store features Bunting Magnets in thousands of shapes and sizes, as well as a wide assortment of magnetic tools for work-holding, lifting, and plant maintenance.
The Sensors Midwest Expo takes place on October 16-17, 2018 at the Donald E. Stephens Convention Center in Rosemont, IL.
Over 2,000 engineers, engineering professionals, and scientists attend Sensors Midwest each year to connect with innovators, leaders and suppliers in the sensors industry. Ideas are shared, connections made, and solutions featuring the latest industry trends are discovered. The two-day event features over 75 exhibitors where the latest technology and products are showcased. Product categories include: acceleration, aerospace, automation sensors, chemical/gas, embedded systems, energy harvesting, flow, force/strain/load/torque/instrumentation, internet of things, level, moisture/humidity, optical, position sensors, presence/proximity, pressure, sensors/system components, software, temperature, ultrasonic, and wireless.
The BuyMagnets.com booth features our N42 and N52 magnets. Neodymium magnets have replaced alnico and ferrite in countless applications where strong permanent magnets are used in modern technology. This is due to the superior strength of neodymium, which allows for the use of smaller, lighter magnets in these applications. Neodymium magnets are the most widely used of all rare earth magnets. Some typical applications that use neodymium magnets include tape recorders, alternators, pacemakers, biasing applications, flow meters, gyroscopes, and linear actuators. Incredibly strong neodymium magnets are available at affordable prices on BuyMagnets.com. Shop our large selection of in-stock rare earth magnets and find the perfect solutions for your applications.
With Bunting Magnetics you receive superior customer service at every stage of the process. All of our magnets and magnetic products meet or exceed MMPA, ROHS and REACH standards. All in-stock products ship within 24 hours. Stop by our booth to learn how BuyMagnets.com can help in your success.
For further information on magnets and magnetic products for your applications, please contactthe experts at Bunting Magnetics and BuyMagnets.com.
A Magnetic Separator is designed to attract, capture and hold magnetic particles. The magnetic strength needed to successfully achieve that design objective is commonly stated in a magnetic separator supplier’s quotation or specified in the tender. This ‘Magnetic Strength’ is usually referenced in terms of ‘gauss,’ a unit of measurement. However, the ‘gauss’ value can be very difficult to accurately measure.
There is a more practical method of assessing the magnetic strength. This removes any ambiguity while providing simple, repeatable, and comparable data to assess most Magnetic Separators.
Accurately testing the strength of your Magnetic Separator is crucial to the success of your operation
Measuring Magnetic Strength
The magnetic strength of a Magnetic Separator is often referenced in terms of ‘gauss’. Gauss (symbolized G) is the centimeter-gram-second (cgs) unit of magnetic flux density. A flux density of 1 G represents one maxwell per centimeter squared (1 Mx cm -2 ). It is named after the German scientist Carl Friedrich Gauss.
Gauss can be measured using a Gaussmeter. However, it is important to note that the Gauss rating on its own does not fully indicate the strength of a magnet. Additionally, gaussmeters can give a range of readings dependent upon the orientation of the probe and several other variable parameters.
Proposals for Tube Magnets often include details of length, diameter and the gauss reading. With the gauss reading being so difficult to test and prove, purchasers and users are unable to check that the Tube Magnets supplied actually meet the specification of the quote and the order.
However, in terms of Magnetic Separation the objective for the user is simple; the magnetic force must enable the attraction and capture of any magnetically susceptible metal. That ability can be measured as a function of the effort needed to remove a specific steel item from the surface.
The Method
A Pull Test Kit ‘Spring Balance’
Measuring the effort needed to remove a steel item from the face or surface of a Magnetic Separator is achieved using a spring balance and is commonly called a ‘Pull Test.’ The magnetic test piece (e.g. a 6mm ball bearing welded onto a non-magnetic attachment ring) is clipped onto the end of the spring balance.
The magnetic test piece is placed on the surface of the Magnetic Separator and force applied at the other end of the spring balance until it is detached. The force required to remove the magnetic test piece (measured in kgs) is recorded on the measurement scale of the spring balance.
Measurements are taken in the center of the Tube Magnet and on the end poles. They are repeated three times and the average recorded as the force required to remove the magnetic test piece at each point.
The following video explains the Pull Test technique.
This simple but effective method does not record or provide any indication of the gauss, but accurately provides data that can be used to compare the condition of a Magnetic Separator over time and compare the performance with other similar designs.
Pull Test Experiments
Magnetic Separator designs vary considerably depending on the application. The Pull Test technique is suitable for measuring the magnetic strength of smaller Magnetic Separators such as Tube or Cartridge Magnets and Plate Magnets.
Tube or Cartridge Magnets are often used stand alone or as part of a Magnetic Separator configuration (e.g. Drawer Filter or Liquid Trap).
Magnetic Test Piece
A small steel ball is used as the magnetic test piece when measuring the magnetic strength of a Tube or Cartridge Magnet (the photograph shows a 6mm diameter ball)
The metal test piece is attached to the end of the Spring Balance and then placed into the magnetic field, being attracted to the magnetic pole.
In a series of experiments, we used the Pull Test technique to assess the magnetic strength of Tube Magnets with Ceramic (Ferrite), Standard Neodymium Rare Earth, and High Strength Neodymium Rare Earth Magnets.
The tests were undertaken using three different sizes of steel ball in the magnetic test piece (6mm, 12mm and 25mm) and introduced non-magnetic spacer to assess the magnetic strength at specific distances away from the surface (3mm and 6mm). All the recorded measurements are in kilograms (kg)
Magnetically Attracted Metal Test Piece
Ceramic (Ferrite)
Gap
6mm Ball
12mm Ball
25mm Ball
None
1.25
1.75
2.5
3mm
NR
NR
1.2
6mm
NR
NR
NR
Standard Neodymium Rare Earth
Gap
6mm Ball
12mm Ball
25mm Ball
None
2
4.25
9
3mm
1.2
1.6
2.45
6mm
NR
1.25
1.5
High Strength Neodymium Rare Earth
Gap
6mm Ball
12mm Ball
25mm Ball
None
3.75
9
14.5
3mm
1.5
2.5
4.6
6mm
1.1
1.5
2.25
In all cases, the drop off in magnetic strength as you move away from the surface of the Tube Magnet is significant and this highlights the need for metal contamination to come into contact with the surface. Arrangements where the Tube Magnets are configured as a Grate (i.e. are lined up and equally spaced) commonly have a deflector above the gap between the Tubes that directs material in the area of maximum magnetic strength.
The tests highlight the difference in magnetic strength on the surface, with high strength Rare Earth magnets producing nearly 3 times as much pull as Ceramic magnets.
Findings During Magnetic Separator Audits
Magnetic Separator Audits often highlight issues that had previously gone undetected. The first check focuses on the physical integrity of the Magnetic Separator, inspecting welds, and assessing wear and damage. Once these have been completed, the measurements are taken.
The most common findings when undertaking magnetic separator audits are:
Weld Failure
Consequence of weld failure on a Liquid Magnetic Filter
Magnetic Liquid Filters, fitted into pipelines, have Tube Magnets that are welded to a lid and project down into the product flow. Metal is attracted and captured on the surface of the Tube Magnet.
In cases where the welds have failed (e.g. poor manufacture, eaten away by acidic or alkaline liquids), liquid will seep into the tube and onto the magnets. The magnets then swell and lose magnetic strength, ultimately splitting the outer stainless-steel casing.
Tube Magnet Wear
When material falls directly onto the surface of a Tube Magnet, over time the surface can be worn. Wear usually occurs on the poles where magnetic particles have been captured. Once the outer stainless-steel casing has been breached, the Tube Magnet should be replaced.
Weak Tube Magnets
Magnetic separation audits highlight the variance in magnetic strength of Tube Magnets. Often, the Tube Magnets have been installed for some time and details of the original specification have been lost. When testing the magnetic strength, some Tube Magnets are found to have very poor strength and provide little if no metal separation protection. This is of great concern when the Tube Magnet is positioned to protect a particular item of processing plant where metal contamination damage could result in production downtime and costly repairs.
Conclusion
The Pull Test Experiments highlight the importance of physically checking the real magnetic strength of a Tube Magnet and not only relying on the stated gauss. Including details of the force needed to detach a 6mm steel ball from the surface of the Tube Magnet in the request for quotation and the order, protects the user and ensures that the supplied equipment is as exactly as stated.
This ‘Pull Test’ measurement technique also enables a regular comparative test that will immediately highlight any drop in magnetic strength. This can be used in annual audits or inspections as part of a plant’s quality management system. A change in ‘pull’ strength may be the result of physical (e.g. failed weld, broken magnets from being dropped) or excessive heat. The reduced magnetic force may result in the magnetic separator no longer being fit for purpose.
For further information on measuring the strength of a Magnetic Separator, please contact Bunting Magnetics.
The theme of the 2018 Recycle Week (24-30 September) in the United Kingdom is ‘Recycling. We do. Because it matters.’ Recycle Week is a celebration of recycling, organised by WRAP under the ‘Recycle Now‘ brand.
Recycling has never been more prominent in the news, with managing plastic waste high on the agenda. We work with many plastic recycling companies and have provided many magnetic separators and metal detectors to remove metal contamination. To celebrate Recycle Week in the UK we wanted to talk about plastics recycling success and also highlight the changes faced by companies recycling plastic.
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. By installing Drawer Magnet Filters, EcoVyn reduced their waste by 94%.
A French plastic recycling company installed the Drawer Magnets to remove fine iron contamination present in the recovered and granulated plastic. If the metal is left in the reclaimed plastic, it causes serious defects in the new plastic product and can also damage processing equipment.
A new plastics recycling plant was built in Kent, UK. The plant was designed to handle up to 25 tonnes per hour of reclaimed plastic. Once shredded, the plastic is passed over a strong Drum Magnet (to remove small ferrous metals) followed by an Eddy Current Separator (to remove non-ferrous metals). The end product is also passed through a Quicktron Metal Detector prior to the clean plastic being bagged ready for shipment.
We work with many plastic recycling companies located across the world. Every company is faced with the problem of contamination. Contaminated plastic waste is worthless and processing is required to remove contaminants, such as metal and stone, to make this waste product reusable.
We are fortunate to be working with some amazing companies in the waste and recycling sector. Their innovation and knowledge continually increases the amount of materials we can recycle and reuse.
On Friday 21st September 2018, one of the many visitors to our Bunting Magnetics and Master Magnets stand at the RWM18 exhibition placed an order for the displayed Eddy Current Separator. The order was confirmed just 8 days after the close of RWM18. Along with the Eddy Current Separator, the customer also ordered a high strength Rare Earth Drum Magnet.
The Eddy Current Separator on display at the CARS exhibition earlier in 2018
“To secure an order of this size so quickly after the show is fantastic,” said Jonathan Millington, Master Magnets Marketing Manager. “It is a testimony to the success of this year’s show.”
The complete Metal Separation Module will be used to process a wide range of stockpiled waste materials by a specialist recycling company based in the UK. The versatile design of the Eddy Current Separator proved to be vitally important for the customer. Due to the variable nature of the feed, it was important to easily adjust the splitter and the belt speed. These can be easily tuned to achieve maximum metal recovery.
The Eddy Current Separator Specification
The Eddy Current Separator comprises of two pulleys and a conveyor. Inside the non-magnetic shell of the head pulley is an eccentrically located magnetic rotor positioned. The magnetic rotor is 190mm in diameter and has 12 poles. The rotor is positioned inside the outer drum, towards the discharge point of the material flow, allowing the concentrated magnetic force to separate metals as they leave the belt conveyor.
The principle of operation focuses on the generation of ‘eddy currents’ in non-ferrous metal particles. The magnetic rotor revolves at around 3000 revolutions per minute whilst the outer drum cover rotates at the speed of the Eddy Current Separator’s belt conveyor. As the rotor spins at these high speeds, an electric current or ‘eddy current’ is induced into conducting metals. The induced electric current produces a magnetic field, which opposes the field of the rotor, repelling the conducting metals over a pre-positioned splitter plate. The remaining materials such as plastics, glass and other dry recyclables will simply free-fall over the rotor, separating them from the repelled metals.
The Eddy Current Separator demonstrated at the RWM18 exhibition had a 500mm wide conveyor fed by a Vibratory Feeder. The high strength Rare Earth Drum Magnet, positioned prior to the Eddy Current Separator, removes any ferrous metal.
“This year’s RWM18 has surpassed all expectations and we are already in the final stages of agreeing other orders for Eddy Current Separators and Overband Magnets,” said Jonathan. “Our laboratory is also booked for at least one month just for tests on the new Stainless Steel Separator.”
The photograph shows a large self-cleaning Electro Overband Magnet packed and ready for shipment to a copper ore mine in Bulgaria. This is the third Electro Overband Magnet purchased by the mine to remove tramp ferrous metal from the crushed ore.
Two Master Magnets Electro Overband Magnets in the final stages of manufacture
Application
The mine is installing the Electro Overband Magnet to remove tramp ferrous metal from conveyed chalcopyrite ore (copper iron sulphide mineral CuFeS2). Chalcopyrite is the most important copper ore with the largest reserves occurring in Canada and South Australia. The Magnet is positioned across an 800mm wide conveyor belt running at 1m/sec carrying 400 tph of ore. A magnetic field is generated by a large coil and projected down into the conveyed ore. Any tramp ferrous metal held within the ore is attracted by the magnetic field, lifted off the conveyor belt, through the burden of material, and onto the face of the magnet. A rotating heavy duty rubber belt with deflectors, then moves the separated metal away from the conveyor and deposits it in a waste collection area. If left in the ore, the tramp ferrous metal causes damage to crushers, conveyors and screens.
The Magnets
Master Magnets Electro Overband Magnet packed and ready for shipment
The latest Electro Overband Magnet is a model 60OCW20. The model of Electro Overband Magnet was selected using a bespoke selection program that takes into account a number of application variables including the burden depth, throughput, material density, ambient temperature, conveyor belt speed, and the separation objective. Once these are assessed, either one of over 300 Electro Overband Magnet designs are identified as being suitable or a bespoke design can be developed.
The model 60OCW20 weighs over 1.5 metric tons with the 3,385 watt electromagnetic coil being cooled by oil. The mine previously purchased two Electro Overband Magnets in 2013: a model 110CW35 (weighing over 5 metric tons) and 950CW40 (weighing over 5.2 metric tons). All the Electro Overband Magnets are designed and manufactured at the Master Magnets headquarters in Redditch, UK.
Export Success
This is the latest shipment of Magnetic Separators to overseas customers.
“Master Magnets has a very strong reputation in the global mining industry and we are recognized as only one of a few magnetic separator suppliers who have vast experience of designing and manufacturing equipment that can survive in the arduous environment of a mining operation,” explained Jonathan Millington, Master Magnets Marketing Manager.
The BBC television series Detectorists (available on Netflix, Amazon Prime or check your local PBS station to see if it is being broadcast in your area) has significantly increased the public’s awareness of metal detectors, but many people remain unaware of their importance in the recycling of waste materials.
Though the size and design of a 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 recognizes 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 Detectors suitable for detecting metal in such conveyed material. The s 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.
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.
In 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.
For further information on Bunting’s range of metal detectors and metal separators for the recycling industry, please contact us at bmc@buntingmagnetics.com
Tesco, Aldi and Nisa Recall Pastry Product Due to Potential Metal Contamination
On June 2, 2018, the Food Standards Agency announced that the Addo Food Group was recalling batches of chilled pastry products, including sausage rolls, pasties, pastry pies and slices because of potential contamination with small pieces of metal wire. This is the latest food safety recall due to metal contamination and the announcement comes seven days before the start of National Food Safety Week.
Addo Food Group manufacture the chilled pastry products as own-branded products for major UK supermarkets Tesco, Aldi and Nisa, as well as those produced under the Walls and Millers brands. The extent of the recall is substantial, with 59 products being recalled.
How Does Metal Get Into Food?
Metal can enter the food production process at a number of stages:
Metal can be present in the foodstuffs being delivered. To prevent such an introduction of metal into the process, many food processors pass the in-feed material over Magnetic Separators and through Metal Detectors;
Processing equipment wear and failure (e.g. screen break, pump collapse, etc.) can cause metal to enter the process stream;
Accidental introduction by people on site;
However, with the right combination of magnetic separation and metal detection equipment, such metal can be found and removed before any finished product leaves the production facility, preventing disastrous and costly product recalls.
How To Prevent Metal Contamination
The vast majority of food processing plants have Magnetic Separators and Metal Detectors installed. Many of these have been in operation for many years which, in some cases, can be decades.
Demonstration of how to use the Bunting Magnetics pull test kit to measure the strength of Tube Magnets and Plate Magnets
Moved and positioned in such a way that it is very unlikely to capture any metal contamination;
Cleaned too infrequently, resulting in a substantial buildup of captured metal until the magnet face is full and the Magnetic Separator no longer operates;
Purchased and installed without any check of the magnetic strength, which subsequently turns out to the very weak;
Installed many years previously and now provides limited protection due to the poor magnetic strength;
To prevent metal contamination problems, it is advisable to have an annual audit by an external third party. This audit then forms part of the quality and safety management system.
It will be interesting to determine the cause of the latest food recall due to metal contamination, but it will take longer to fix the damage done to the reputation of the manufacturer Addo Food Group and consumer confidence in the affected products.
For more information on the issue of Metal Contamination and Metal Separation, or to arrange an onsite audit and survey of a particular plant or process, please contact us at:
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