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13/02/2017 Teardrop tube magnet

Bunting Magnetics Europe, Berkhamsted, UK, has developed a new design of rare earth tube magnet for use in removing fine iron particles from dry powders.  The Teardrop tube magnet retains a high surface magnetic field of 12,000 gauss, but the shape prevents fine powder from building up on the surface. Tube magnets are used extensively in the process industries to capture magnetically susceptible foreign bodies, including screws, nuts, bolts, and small iron shards, in both dry and wet applications.  They are commonly used in the form of a grate magnet, where several tubes form a magnetic separation grid.
The new Teardrop magnet has the point of the tear orientated into the product flow.  The surface area on the point of the tear is very small and prevents fine powder collecting on the surface.  The powder then flows under gravity over the side of the tube magnet, with any magnetically susceptible materials attracted to the high magnetic force.  These particles migrate to the bottom of the tube magnet, where they are securely held away from the product flow. Even though conventional rare earth tube magnets have a circular cross-section, fine non-magnetic material often builds up on the upper-most point of the tube.  Over time this ‘bridging’ can increase and ultimately cause a blockage.  The build-up always reduces the separation performance, increasing the likelihood of metal contamination continuing through the process. 
The Bunting Teardrop tube magnet and (below) showing how magnetically susceptible materials are captured at the bottom

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