In order to extract ferromagnetic components which are contained in ores, the ore is ground into a powder and the powder obtained is mixed with water. A magnetic field generated by one or more magnets is applied to this suspension, as a result of which the ferromagnetic particles are attracted so that they can be separated from the suspension.
DE 27 11 16 A discloses a device for separating ferromagnetic particles from a suspension, in which a drum consisting of iron rods is used. The iron rods are alternately magnetized during the rotation of the drum, so that the ferromagnetic particles adhere to the iron rods while other components of the suspension fall down between the iron rods.
DE 26 51 137 A1 discloses a device for separating magnetic particles from an ore material, in which the suspension is fed through a tube which is surrounded by a magnetic coil. The ferromagnetic particles accumulate at the edge of the tube, while other particles are separated through a central tube which is located inside the tube.
A magnetic separator is described in U.S. Pat. No. 4,921,597 B. The magnetic separator comprises a drum, on which a multiplicity of magnets are arranged. The drum is rotated oppositely to the flow direction of the suspension, so that ferromagnetic particles adhere to the drum and are separated from the suspension.
A method for the continuous magnetic separation of suspensions is known from WO 02/07889 A2. This uses a rotatable drum in which a permanent magnet is fastened, in order to separate ferromagnetic particles from the suspension.
In known devices, a tubular reactor, through which the suspension flows, is used to separate the ferromagnetic particles from the suspension. One or more magnets are arranged on the outer wall of the reactor and attract the ferromagnetic particles contained in it. Under the effect of the magnetic field generated by the magnets, the ferromagnetic particles migrate onto the reactor wall and are held by the magnet arranged on the outside of the reactor. Although this allows effective separation, the separation method can however only be carried out discontinuously since after a particular quantity of the ferromagnetic particles have accumulated, the reactor has to be opened and the ferromagnetic particles removed. Only then is it possible for a new suspension to be supplied, or for the suspension already used once to be subjected to the separation method again.