Low- and high-intensity magnetic separation

The mining and recycling industry currently uses mainly magnetic separators with conventional circuits (or traditional magnetic circuits with copper resistive coils) and permanent magnets (ceramics).

The first applications of magnetism in ore beneficiation date back to the end of the 18th century, when permanent magnets were used to concentrate magnetite iron ore. The first high-intensity wet separator was patented in 1897, and the first high-intensity dry separator went into operation in 1908.

The development of this technique has been relatively slow, and efforts have focused on high-intensity dry separators. It wasn't until 1970 that a high-intensity (120 t/h) wet separator was installed on a mining site in Brazil. This was the starting point for rapid development, which is still very promising, as current research shows.

This technology is used in an ever wider range of fields, for concentration or purification, and its scope of application is expanding into sectors where its use was not previously envisaged (environment, recycling, chemistry, biology, etc.).

Using efficient technology, this separation method is becoming a leading-edge technique, both in terms of the diversity of elements it can process, and in terms of the role it can play in a wide range of production sectors. Now recognized as a major technological tool, magnetic separation is rightly seen as a process whose future development holds great promise.

The key component of a magnetic separation device is the magnetic field source which generates the force used for separation.

Technological advances in the manufacture of permanent magnets have led to the emergence of Nd-Fe-B magnets with higher specific energies than Sm-Co magnets.

The complete study of the subject includes the articles :

• J 3 220 "Magnetic separation: theory and modeling" ;

• J 3 221 "Low- and high-intensity magnetic separation" (this article) ;

• J 3 222 "High gradient magnetic separation (HGMS) and high field" ;

• J 3 223 "Magnetic separation: economics and special applications" ;

• Doc. J 3 224 "Magnetic separation. Find out more".