WEEE recycling and its problem: BLACK PLASTIC

Recycling of toner cartridges

Recycling of toner cartridges is a particular challenge. Approx. 370,000,000 toner cartridges were sold worldwide in 2010, whereby certainly most of them had been used and emptied from printing tasks already within a short period of time, thereby soon becoming scrap items. Specialised refilling companies refill some of these toner cartridges, others are collected by the producer and recycled. But the largest proportion of them end up as refuse, as there has been no suitable recycling process in place for this type of mixed product (see Photo 4).

But electrostatic separation is also ideal for recycling plastics from toner cartridges. Following shredding, removal of residual toner ink, separation of metal parts and float-or-sink separation to concentrate the plastic materials, a completely black mixture of PS and ABS is obtained. This material has particle size < 10 mm and is then largely separated from metals and elastomers in a first stage by the hamos KWS corona-roll electrostatic separator. Elastomers in toner cassettes are mainly electrically conductive, so they can be easily separated out by conductive/non-conductive material separation. As trials have shown, it is possible with multi-stage separation to reach rubber contents as low as just several ppm!

Photo 4. Toner cartridges

Subsequent separation in the hamos EKS electrostatic separator easily separates out clean plastic fractions such as ABS or PS. As separation takes place irrespective of colour, these completely black materials can be easily separated into fractions of very high purity.

After running through the recycling line, the granulated ABS and PS materials become so clean that they can be used again in production of new toner cassettes. So a completely closed circuit is obtained, “from the toner cassette to waste, via clean granulate to the new cassette”.

A large part of the valuable resources contained in a toner cassette are recovered in this way. It is therefore possible to utilise almost the entire recyclable material potential in these toner cassettes. This was not possible in the past, as no success had been achieved in separation of the black plastics from each other into separate pure fractions according to the type of plastic. Without electrostatic separation possibilities, most of the black plastics involved would have been thermally recovered, i.e. they would have landed up in incineration.

Selinda Sliz
Marketing Director
hamos Gmbh