To ensure maximum efficiency of metal removal it obviously had to be carried out at the end of processing, however this gave problems in that at this stage the material was in pulverised form so was dry and dusty. During discussions between Atritor and Master Magnets it was decided therefore that the separation equipment should be totally enclosed and as far as possible dust sealed. Also since both ferrous and non ferrous metals could be present the equipment would have to be capable of removing both, and would have to do so automatically with minimum interruption to the process.
 

The solution decided upon was to use a magnetic drum separator in a sealed housing to take out ferrous metals followed by a metal detector to remove non ferrous metals. Pet coke would be fed to the top of the drum, and discharge from the drum onto a short belt conveyor. Any ferrous metal would stick to the face of the drum and be carried around it to discharge to the rear. The metal detector would then stop the conveyor on finding non ferrous metal, then reverse it to discharge the metal from the same outlet as the drum. This combination would ensure that the material flow is interrupted only for a few seconds only when removing non ferrous metal, and there is no interruption when removing ferrous metal.
 

The sketch shows the layout of the equipment, throughput was to be 4tph, so it was designed around a 300mm diameter x 450mm long magnetic drum to cope with this. The 500mm wide belt conveyor was flat with sidewalls to prevent spillage, and was just long enough to incorporate the metal detector. The casing design allows access to the metals detector, and allows the drum to be removed for servicing. Bearings and drum drive motor are external, the conveyor has a motorised pulley drive.