I believe the grain grinding process eliminates ferromagnetic metals by the use of magnets. "Zapory ferromagnetyczne" is more a marketing hype than a technological name.

zapory ferromagnetyczne,
usunięcie metali ciężkich na poziomie do 90%
http://lubelskie-mlyny.pl/jakosc

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What Are The Different Types Of Grain Milling Equipment

. The next section of the assembly line is composed of disc separators that only allow certain sized objects through in order to get rid of smaller objects such as barley and oats. The next step contains one of the most critical pieces of grain milling equipment, the magnetic separator, which is responsible for the health safety of the granules. The mixture is placed through this magnetic and ferrous material is pulled from the batch.

http://www.philiprahm.com/what-are-the-different-types-grain...

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TurboGrate™ Magnetic Separator features a powerful motorized rotating grate magnet to remove ferrous metals from powder and granular materials.
https://buntingmagnetics.com/industries/grain-and-milling/

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As grain is needed for milling, it is withdrawn and conveyed to the mill area where it first enters a separator (a vibrating screen), then, an aspirator to remove dust and lighter impurities, and then passes over a magnetic separator to remove iron and steel particles.
https://www3.epa.gov/ttnchie1/ap42/ch09/final/c9s0909-1.pdf