How to Recycle Curb Side Plastics

Co-mingled Recycling is already being sorted in MRFs all over the country with bales of mixed plastics a major and important output stream. So what do you need to do to get it to the next level.

First you need to understand what you have and what you want to achieve. With contamination varying depending on region and effectiveness of the MRF/s it can be difficult to get hard data on this. So for this step you need to get your hands dirty. You need to sample and manually sort bales from each potential collection location/MRF at least 2-3 times with a few weeks separating each sampling. Importantly if your project stretches out we recommend on going testing to determine if their are changes showing through.

Once you know what you have it is important to know what you want to do. Is your goal minimum processing for export to China? Industrial grade material that can be sold as a raw material? or Food Grade specifications for sale direct to product manufacturers?

With this information in hand you are ready to work out Machinery, Plant and Layout. This will vary depending on your input and output but almost definitely you will need to use an Electronic Sorter. Some sorters like the SESOTEC Varisort are able to detect and sort using Near Infr-Red

Feeding of the material to be inspected is effected by specifically adapted vibration chutes that guarantees a homogeneous material distribution over the full width of the fast-running conveyor belt. By combining inclined chute and conveyor belt the influences of mould, weight and abrasion of charging material are eliminated. At the end of the belt the material is classified with the corresponding sensors detecting Polymer, Colour and Metal simultaneously. After the evaluation of relevant information, high-speed pneumatic valves are activated with a corresponding time delay to blow out the material from their original fall parabola into a separate duct as shown in this video.

So once the plastics are sorted by Polymer, Colour and predominantly free of contamination, both metallic and other, it is ready for Grinding and Washing. This includes a series of Size reduction and agitating washing steps accompanied by a Hot Water and Solution Treatment step to remove residue liquids, adhesives and further contamination such as PVC labels attached to PET bottles.

Following washing is a simple drying process consisting of a High Speed Mechanical Spin Dryer. At this point the material/s can be air screen to remove any fines and bagged ready for sale to your customer. If however you want to reach Food Grade quality (Generally limited to PET) then a final stage of electronic sorting is required. For this we must use a highly specialised machine like the SESOTEC Flake Purifier shown in the below video.

David Picone

General Manager - Australia

Telford Smith Engineering - Designers and Manufactures of Complete Recycling Solution