Magnetic separation will be the second waste separation technology utilized in the MRF. Magnetic separation is a well-proven and established technology and is an obvious component of every MRF, whether manually or mechanically intensive. Magnetic separation removes the ferrous metals from the other commingled recyclables based on the attraction between ferrous metals and the magnet. This attraction exists due to the magnetic dipole properties of ferrous materials, which form a net magnetic field when exposed to an external magnetic field.
The ferrous separation employs an overhead self-cleaning electromagnet that uses an electric current that runs through a coiled wire to generate the magnetic field. The most important aspect of the technology is selecting the strength of the magnetic field so that the magnetic force can overcome the weight of the material and lift it from the stream. The necessary magnetic strength therefore depends on both the weight of the material and the distance of the material from the magnet. Gravity and the gap between the magnet and the conveyor keep other materials out of the product stream. The ferrous materials do not actually hit the magnet, rather they are directed to a bin by a conveyor with flights that runs along the magnet. In order to utilize the entire magnet, the feed conveyor is located directly under the magnet. The rate of extraction will be used to determine the optimal speed of the conveyor to achieve the highest efficiency possible. Once the ferrous materials are separated, they can be either shredded or baled depending on market specifications.
