A Guide to the Ideal Location for Magnetic Separators and Metal Detectors in a Tyre and Rubber Recycling Plant
Successfully removing the metal banding from rubber when recycling tyres is critical as rogue metal can cause injury to horses and children who run and play on the rubber crumb. Although each tyre recycling plant is different, here is a guide to the types and location of Magnetic Separators to remove the steel.
The biggest challenge with removing all the steel wire from shredded tyres is to maximise separation whilst minimising product (rubber) loss. This means that multi-stage Magnetic Separation is required.
As shown in the typical plant layout, the primary objective is to liberate the rubber from the metal and this is commonly achieved with a 2-stage shredding set-up. This achieves optimum size reduction whilst also producing a rubber crumb material that is well liberated. After the 2nd stage of shredding, it is then possible to focus on the separation of the steel.
Step 1 – Primary Magnetic Separation after the 2nd Shredder
At this stage, the objective is to separate the bulk of metal and this is achieved using a high strength Twin Pole Overband CBS Magnet. The Twin Pole Overband produces a deeper and stronger Magnetic Field to lift and separate small wires and wire still entrapped in rubber (as explained in the blog The Benefits of a Twin Pole Overband Magnet);
Step 2 – Magnetic Separator Treatment of the Separated Metal Fraction
As there will be clean rubber product carried over into the separated metal fraction, the material can be passed over a Magnetic Drum Separator or Magnetic Pulley or the High Intensity Separation Conveyor (also known as the Stainless Steel Separator), all using high strength Rare Earth Magnets. It is important that either of these has an Axial magnetic field (one that runs along the length of the Magnetic Separator) as this causes the material to tumble and release entrapped rubber. If a Magnetic Drum is uses, then consideration is needed for either a manganese steel shell or wear cover as the strong magnetic characteristics of the steel wear can result in heavy wear;
Step 3 – Secondary Magnetic Separation
A second stage Magnetic Separation treatment of the primary rubber product prior to storage is recommended to remove any stubborn metal left after the first stage separation. This is achieved using a second Twin Pole Overband CBS Magnet;
Step 4 – Magnetic Treatment of the Rubber Powder
For fine rubber material, that is fed onto a powder grinder, a final stage Magnetic Separator is needed to remove small fragments of wire. As the volume of metal is low, a Plate Magnet suspended close to the product over the conveyor will lift and remove the fine wires;
The 4 steps outlined are generalisations in line with work Bunting has conducted with tyre recyclers around the world, but each plant is often unique. When considering metal separation, either from the start or to improve on the level of metal separation presently being achieved, a review of the plant by one of the Bunting or Master Masters Application Engineers will enable the recommendation of the optimum design and location of a Magnetic Separator.
For further information on removing Metal from Recycled Tyres using Magnetic Separators, please contact the Bunting technical sales team on: