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Metal Detector / Metal Separator

Industrial detection and removal of Foreign Bodies from bulk solids processes

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Section summary
1. Technology of metal detectors
2. Rejection
3. Chosing the right metal detector

Metal detectors are totally different than simple magnets. They are not going to trap metals but will detect metal presence in a product stream and possibly reject it making them very useful metal separators for process industries handling bulk solids. This page is essentially focused on gravity fall - free fall metal detectors.

1. Technology of metal detectors

How is the detection performed ?

When metal is passing through the metal detector, it will change the magnetic field that is applied by the metal detector. This disruption will allow the detection of the presence of metal.

2. Rejection

How are metal detectors removing foreign bodies ?

Metal detectors can be equipped with a rejection. It takes most often the shape of a flap that is opened as soon as the metal detector spots the presence of metal in the product flow. It is the principle used by safeline metal detectors for example.

Each time a diversion occurs, some product is lost, it is important not to have false detection otherwise a lot of losses will be generated.

3. Chosing the right metal detector

What are the parameters guiding the choice of metal separators ?

The following parameters must be taken into account when chosing a metal detector : the product throughput to handle, the location of the metal detector and the sensitivity targetted

Table 1 : Metal Detector design criteria

Design parameter Consideration to keep in mind
Detection limit Metal Detector Diameters
Minimum powder speed Distance powder point of chute - entry of metal detector
Powder max throughput Ensure that the powder flow is roughly dosed
Metal detector Diameter
Performance check Access to Metal Detector entry - introduction of test balls / rods
Position in the process The majority of metal detector are used in gravity fall application but some manufacturers can propose metal detectors designed for pneumatic conveying line for instance

Other related sections

Sifter / Vibrating sieves



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