Getting it sorted

Kurt Palmer, Area Manager, Environmental - Australia & New Zealand, Steinert Australia, talks about the new UniSort line of sorting machines developed by RTT Steinert which uses a range of detection and separation technologies to automatically sort waste at different points along the recovery and recycling path.

Recycling should be a whole lot easier than it is. After all, we go to great lengths to extract impure raw materials then invest large amounts of energy in purifying and processing them and turning them into useful products.

The problem is, we then have the habit of taking those purified materials - the polyethylene in a plastic milk bottle for instance, or the copper in a phone charger - and mixing them up with a whole lot of other stuff when we throw them away.

Why do we ‘devalue’ our discarded plastics and metals to such a degree? There are many reasons, but one of the main ones is that it is simply the most convenient thing to do.

We’ve come a long way from the early days of kerbside recycling, when paper, tin cans and glass were collected separately. Now our recycling bins accept a wide range of different materials. This provides the convenience factor that has lifted the recycling rate, but also created twin challenges for the people in the materials recovery game: how to handle the mix of materials and how to handle the volume of materials?

This is where smart technology steps in. The UniSort line of sorting machines developed by RTT Steinert uses a range of detection and separation technologies to automatically sort waste at different points along the recovery and recycling path.

The first pass is usually through a UniSort PR machine at a materials recovery facility. This sorts large items such as whole soft drink bottles and achieves a high level of purity. However, it isn’t perfect. The actual bottle may be made with one type of plastic, and the collar around the neck made from a different, incompatible plastic.

Not to worry. Before plastics can be recycled into new product, they need to be shredded into small pieces. In this process, bottles and collars, or other composite items are reduced to individual flakes of homogenous composition.

This gives the UniSort Flakesorter a chance to work its magic. The UniSort Flakesorter handles particles of plastics, metals and other materials in the range of 5-20 mm, with the composition of each flake being determined using one of two methods. Near infrared (NIR) technology differentiates between a range of plastics including PET, re-granulated PVC, PE, PS or PP. Colour sorting is used to separate aluminium and lead from copper and copper wire. Once identified, each flake is diverted into the appropriate collection bin with a puff of compressed air.

At just 3 m long and with a sensor only 0.75 m wide, the UniSort Flakesorter can handle an incredible 24 million flakes/s. More importantly, a much higher efficiency and resolution is achievable with this machine. Higher purity makes it easier to incorporate recycled materials into new products and increases their value.

There are many links in a successful recycling chain, and materials sorting is becoming an increasingly important one. By installing UniSort Flakesorters, recycling facilities can increase both their throughput and the purity of their recovered materials, assisting in the creation of higher value recycled products. Aside from making sound business sense, that has to be good for everyone.