Image courtesy of Eisenmann


Ferrous metal contamination damages process equipment and creates impure product that must be scrapped or sold at less than full value. The contamination may originate within the production process due to material processing, pressing, grinding, drilling or general abrasion. The problems associated with ferrous metal contamination can be reduced or eliminated by using magnetic separation equipment. Magnetic separators, available in a variety of designs, will remove ferrous material such as metal dust and weld balls and other contaminants from liquids. The proper use of this equipment will reduce or eliminate metallic contamination from the process.

Selecting the proper magnetic separator requires an understanding of magnetic properties, the process application and environmental elements that exist in each specific installation. This guide provides a basic understanding of how to choose the proper magnetic separator for different process requirements. Beginning with a magnet material overview.

Magnet Materials & Styles


Magnet material generally refers to the magnetic pressings or castings used to develop the magnetic field within the separator. Once the magnetic system is assembled, it is encased within stainless steel to protect the magnet material from damage or from wear associated with product flow.

Rare Earth

The term, Rare Earth, is a misnomer. A rare earth magnet derives its name not because it is rare, nor because it is earth. It is named “Rare Earth” because part of its make-up is one of the Lanthanide elements of the Periodic Table between 57 and 71. There are 14 elements referred to as “The Rare Earth Elements.” Samarium Cobalt was the first such material used in the early 1980s. The next material on the market was Neodymium Iron Boron, called “Rare Earth” because Neodymium, like Samarium, is one of the Lanthanides. Today, Rare Earth magnetic circuits produce a magnet force more than 10 times that of ceramic magnetic circuits.

MHD Rare Earth Material develops an extremely high surface force to enable the magnetic circuit to remove very fine or weakly magnetic contamination such as rust, scale or even work-hardened stainless steel from a product flow. High strength Rare Earth Separators are extensively used by metal pretreatment processors in the automobile manufacturing industry requiring the highest levels of product purity.

Application Considerations

Flow Rate

Magnetic separators perform best when the contamination is presented to the separator in a timely manner. It is best to select a magnetic separator to the system pump flow rate to ensure the magnet system will have the best opportunity to capture the ferrous contamination. Side stream separation is not considered effective separation as it only removes a small portion of the contamination allowing the remainder to accumulate leading up to an untimely shut down for total bath cleaning.

Flow Characteristics

Production processes may exhibit different flow characteristics. Will the product flow freely through the selected magnetic separator in a timely manner, batch wise or stop-and-go.

Process Issues

How will the fluid be presented to the separator? Is it a continuous stream or do we need to handle a surge flow? Can the system be stopped for cleaning or is a bypass system required? Is a connection available for draining? How much contamination is to be removed? And finally, what level of product purity is required?

Simon Stevinstraat 1
NL-3261 MG Oud-Beijerland
The Netherlands