US4338169A Pcess for promoting physical and/or chemical reactions performed in a fluid medium

https://patents.google.com/patent/US4338169A/en?q=B01F13%2f0809&oq=(B01F13%2f0809)

The process comprises subjecting a magnetic material dispersed in the fluid to the action of a variable magnetic field. It is thus possible to provide efficient stirring of this fluid and to facilitate reactions taking place, between a constituent of the fluid medium, and particles dispersed in this fluid, including a substance at least partly active at the surface. They may be, in particular, a ferromagnetic solid substance and a compound in solution in the fluid and non-magnetic.