Permanent magnet is the simplest type of magnetic separator. Its strong magnetic field can attract and separate iron-containing materials. As the material passes through the magnet, the iron impurities are attracted to the magnet, causing separation.
Different magnet materials have different properties, so selection is very important. The type of magnet material depends on the density of the product, flow rate, operating temperature, and the type of ferrous contaminant you are trying to remove.
Rare earth magnets used in permanent magnetic separators include neodymium iron boron, samarium cobalt, alnico and ferrite.
- NdFeB magnets have the highest strength and are suitable for situations where product density and flow rate are high, as well as when weak magnetic debris and work-hardened steel are encountered.
- Samarium cobalt and alnico magnets are weaker but can withstand higher temperatures.
- Ferrite magnets are lower in strength but can produce a deeper magnetic field and are often used to separate miscellaneous iron with larger particle sizes. It can also withstand higher temperatures and exposure to corrosive elements.