The type of ferrous metal separated at this stage includes steel spanners, nuts, bolts, screws, fi ne metal wires, springs, iron shards, fi ne ferrous dust, and chunks of st ainless steel. Most of the ferrous metal was not part of the original plastic packaging and has been introduced between disposal and processing.

The cleansed plastic waste then passes over an Eddy Current Separator to remove non-ferrous metals. These metals include aluminium drinks cans, foils, tubes, and even window frames.

a specialist UK plastic recycling plant or overseas to countries such as China.

Specialist plastic packaging recycling plants in the UK have been under intense fi nancial pressure for many years. There have been calls for better legislation and governmental support, but too many plastic recycling plants open only to prove fi nancially unviable and then be forced to close.

Specialist plastic packaging recycling plants in the UK have been under intense fi nancial pressure for many years.

Metal contamination found in plastic waste

A typical plastic recycling operation needs a complex system of separation equipment. The plant also needs to be able to adapt to huge variations in the nature of the delivered waste plastic. There are also strict environmental regulations on storing and handling waste plastic. Such plants are expensive to install and operate.

Early in the process, ferrous and non- ferrous metal contamination is removed from the waste plastic using Magnetic Separators and Eddy Current Separators. Initially, after the plastic is released from the compacted bale, the waste is fed into a primary shredder. To protect the shredder from damage, an Overband Magnet is suspended across the feed conveyor which removes large ferrous metal.

At this stage, the type of ferrous metal contamination found in the plastic

SHWM February, 2019 19

is diverse and often surprising. It can include metal packaging mis-sorted at the MRF, heavy lumps of iron that increase the weight of the plastic bale, and metal picked up during transportation. There have even been reports of car engine blocks. Reasonably sized items of cast iron entering the shredder will cause signifi cant and costly damage and result in the plant being closed until a repair is possible.

After the primary shredder, the waste plastic has been reduced in size and many contaminants removed. This shredded waste plastic is fed onto another Magnetic Separator, commonly a Drum Magnet or Pulley Magnet, to remove smaller ferrous metals.

After the metal contamination has been removed, the plastic waste moves to the next stage in the plant, which could be further separation of contamination or sorting by colour or plastic type.

The high level of metal contamination highlights the challenges facing waste plastic processors. It is just one of many contaminants not present in the original plastic packaging that have to be removed.

Before UK and EU government offi cials make recycling pledges to pacify environmentalists, they need to consider the practicalities and diffi culties faced when processing waste plastic packaging. Contamination will always be present, and is one of the reasons for exporting this diffi cult waste material overseas. Reducing such contamination will make it easier to recycle waste plastic, but there is no clear strategy to achieve this goal at present.

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