There are several things to consider when selecting magnets for milling applications. Different magnet designs suit different locations and product types, so it is very important to choose the magnetic separator most suited to the application.
Some important things to consider when choosing a magnet for a milling application:
- The nature of the product – is the product abrasive?
- How often would the magnet need to be cleaned and how accessible would it be?
- Would there be a risk of injury to the operator?
- Would the magnet provide adequate coverage without causing blockage?
- Is the magnet certified by HACCP International and compliant to Food Safety Standard 0909MAGSEP 1-2010?
- How would the magnet strength and condition be maintained?
- Is the magnet supplied with adequate certified documentation and compliance certificates?
The flour milling industry generally utilizes magnetic separators in the following areas. Let’s have a look into each area and which magnetic separators are recommended and why:
Intakes and first break – wheat & grain cleaning
Magnets in these areas are used for removal of tramp and large metal pieces, prevention of dust explosion caused by metal entering high impact machinery, and prevention of damage to high impact machinery, e.g., first break roll.
Commonly used magnets include plate magnets, hump magnets and drum magnets. Due to excessive wear and abrasion of grain, drawer style magnets were not usually considered effective – until the development of the Mag-Ram® Automatic Self-Cleaning Separator.
This design removes the need for any of the above-mentioned designs. The low-profile system needs very little headroom, has built in contingencies for anti-abrasion with the special Dura-Slik® Ram design, and an ever-changing contact point on the bars.
Magnetic separators are installed mid-process for protection of whiteners, color sorters (grain/rice), sieve and sifter conditioners, rotary seals, pneumatic transfer lines, etc.
Rapidclean® Grate Magnets and are recommended prior to whiteners, sieves, and sifters, and have rotary seals to protect against damage. Mag-Ram® Self-Cleaning units are also excellent choices for these and conditioning and color sorting locations as they are durable, resistant to abrasion and have dependable in-stream cleaning features and reduce downtime and operator cleaning time.
Spherical Blowline Magnets suit pneumatic transfers, especially low-abrasion transfers of wheat/rice flour, semolina, bran, and soft grains such as barley, sesame seeds and quinoa.
Final packing and bulk outloading
GRAVITY BAG FILLING
Magnets are usually placed under storage hoppers or immediately prior to packing equipment for optimum efficiency and to reduce the risk of metal contamination from any moving parts or upstream mechanical equipment that finds its way into the product.
The Rapidclean® Drawer Magnet and Mag-Ram® Self-Cleaning Magnet are ideal for small bag (e.g., 25 kg / 50 lb.) filling. Their designs cover key final magnet considerations such as coverage, strength and easy-clean features which enable metal fragments to be easily collected for analysis and quantifying.
PNEUMATIC TRANSFER LINES FOR BULK FILLING OR STORAGE HOPPERS PRIOR TO PACKING OR OUTLOADING
Conventional blowlines usually consist of either dual plate systems, cartridge and torpedo style magnets, and in some cases, bar magnets installed transverse to the flow of the product. Whilst these may be adequate for machine protection, they are often ineffective in separating small magnetic fines contamination.
1” / 25mm bars (or similar) positioned in a housing or slide-out type drawer transverse to the product flow do not provide enough surface area underneath the bar to ensure the collected fragments are retained.
Magnattack® Spherical Pneumatic Transfer Magnets are an extremely effective means of collecting fine weakly-magnetic fragments from final flour and milled products, and can be positioned upstream of cyclone storage hoppers or in bulk fill blowlines to tankers, etc.
The bulk of the high intensity magnetic energy that the RE80® Spherical Magnet produces, combined with the high coverage and surface area of the Spherical element, ensures that extraction of weakly-magnetic fragments in high velocity blowlines is extremely successful.
Gravity bulk outloading
Usually, drawer-style magnets are used in these applications, although sometimes this can be difficult due to limited access for cleaning.
Where a platform or catwalk is available to access the magnets for cleaning, Magnattack® will often suggest the Rapidclean® Drawer Magnet design which has either a swing-over or swing-away drawer design, depending on the available headroom.
Where space and access are difficult, the Mag-Ram® Self-Cleaning Separator is used to ensure magnetic coverage is maintained and the magnet can be frequently cleaned without the need to access.
For more information and to get in touch with a sales rep, visit Magnattack® Global.