The Bunting system helps remove metal contaminates from recycled plastics. (Image: Paul Fears photography)
Kent-based Recapture Plastics has installed a complete Metal Separation Module and Metal Separator from Bunting Magnetics Europe Ltd to cleanse recycled plastic of metal contaminants.
The equipment is housed in Recapture’s new plant in Rochester, which is designed to handle up to 25 tph infeed of recycled plastic material with a view to future expansion.
The plant started processing material in November 2015, just three months after Recapture moved into the premises. Plastic is sourced from across the UK, mostly in baled form, and the operation is one of a few recycling plants with the ability to process and separate the materials effectively.
The process for metal-free plastics
The plastics recycling process designed by Recapture Plastics has a number of key stages. Initially, the bales of mixed plastics are broken up and shredded to reduce the particle size and liberate materials to enable optimum separation. The shredded plastic mix then passes over the Bunting Metal Separation Module where a strong Drum Magnet removes ferrous metals and then an Eddy Current Separator ejects non-ferrous metals.
The Bunting Drum Magnet is designed with strong permanent Rare Earth Magnets configured in an axial magnetic field. This enables high levels of separation with a minimal loss of clean material.
The shredded plastic is evenly fed onto the top of the Drum Magnet by a large Vibratory Feeder with out-of-balance motors. Any ferrous and weakly magnetic material becomes magnetically attracted to the surface of the non-magnetic stainless steel shell by the stationary magnet element inside the Drum Magnet. Attracted metal then moves with the rotational motion of the non-magnetic outer shell until it leaves the magnetic field and is deposited in a waste chute directly underneath the drum, away from the shredded plastic.
The ferrous-free plastic fraction falls evenly onto the conveyor of the Bunting Eddy Current Separator, which transports it into the rotating magnetic field. Non-ferrous metals, such as aluminium, brass and copper, are propelled away from the rotating magnetic field and non-metallic shredded plastic over a strategically-placed adjustable splitter. This enables a clean separation.
The cleansed plastic fraction continues through the process, which includes polymer sorting and further size reduction before passing through a Bunting Quicktron Metal Separator. This final stage of metal separation is positioned to remove any metal freed during the second stage of shredding.
The shredded plastic then falls down an inlet pipe into the Electromagnetic Field of the Metal Separator search coil. Any metal alters the high frequency magnetic field generated by the search coil signalling contamination and a signal is sent to the double actuating air cylinder of the reject assembly underneath the unit. The metal contamination, with a minimal amount of clean material, is then diverted out of the clean material flow and into a waste collection area. Often this is recycled to reduce product loss. The reject time is adjustable to suit each specific application. After the metal has been removed, the reject flap returns to the normal position, once again allowing clean product to flow through.
The metal-free plastic moves onto a washing stage and colour sorting prior to bagging for shipment.