The separation of the valuable mineral can take place after the ore is crushed, ground, and classified into the required particle size distribution. Sorting, gravity and dense-medium separation, magnetic separation, froth flotation is common four separation methods.
Magnetic fields of various intensities can be provided by permanent or electromagnets. Generally, magnetic separators are classified as low or high intensity and whether they work in wet or dry applications. The low intensity magnetic separator working as following:
Magnetic separations take advantage of the magnetic properties of minerals. All minerals will have one of three magnetic properties: ferromagnetic, paramagnetic, and diamagnetic.
- Ferromagnetic minerals (i.e., magnetite and pyrrhotite) are magnetic and are easily separated from other minerals, since they will be attracted to the poles of a magnet.
- Paramagnetic and diamagnetic minerals are not magnetic, but differ in how they interact with magnetic fields. Paramagnetic minerals are weakly attracted whereas diamagnetic minerals are weakly repelled along lines of magnetic forces. Thus, if a mixture of paramagnetic and diamagnetic minerals is passed through a magnetic field; the paramagnetic minerals will be pulled into the field and the diamagnetic minerals will be repelled or separated from the field. Furthermore, paramagnetic minerals have different intensity of paramagnetism that can also be used to effect separations.