Bunting offers up armour for Overband Magnet applications - International Mining

The highest wear part on an Overband Magnet is the belt that transfers the separated metal away from the conveyor and into a collection area. In order to reduce such wear in applications from mining to recycling to biomass power plants, Bunting has developed a special lightweight armouring for the rubber belt.

In operation, an Overband Magnet sits over a conveyor transporting materials such as mined ore. The magnetic field of the Overband Magnet, generated by either a permanent magnet or an electromagnetic block, attracts ferrous metal from the conveyed material up and onto the revolving self-cleaning belt. Rubber upstands on the belt catch the lifted metal, transporting it away from the conveyed material into a separate collection area.

The force of the ferrous metal striking against the self-cleaning rubber belt is significant due to the magnetic attractive energy of the permanent or electromagnetic block increasing as the metal moves closer to the face. This means the metal is accelerating into the belt. The moving belt becomes sandwiched between the lifted metal and the magnetic block momentarily, until the upstand catches and drags the item away and out of the magnetic field.

Applications in which self-cleaning belts experience high levels of wear include:

To combat the excessive wear and extend the life of a self-cleaning belt, Bunting’s engineers designed a lightweight but heavy-duty armouring for the belt. There were other options, including special wear-resistant belt coatings and other types of rubber belt, however the armouring provided unrivalled protection, significantly lengthening belt life, Bunting says.

The armouring on the rubber belt is comprised of high-density polyethylene (HDPE) slats. Each slat is 100-mm wide and 10-mm thick, with a length to suit the model of overband magnet. The slats are fastened to the belt using special 304 stainless steel elevator bucket bolts and nyloc nuts.

“The introduction of this design of armoured belt has proven very popular,” Adrian Coleman, Bunting’s Technical Director, says. “Other types of belt armouring have proven unsuccessful, but the HDPE has worked exceptionally well.”