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Visit to Recycling Centre
By Chris Warrell
History was made on 21st February 2007 when eight members and guests assembled at Greenwich Council's Materials Recycling Facility (MRF) in Thamesmead for the club's first non-Meccano outing.
We assembled in a conference room and were invited to look at the various objects made from recycled materials displayed around the room while we waited for the tour to start. It was pointed out that these items were not made at the MRF, but produced in a cottage industry; there were items made from recycled glass and objects, such as a stapler, that used an old circuit board as its base.
We were also given a pack of free goodies: a recycled note pad, a pencil made from recycled CD cases, a pencil sharpener in the shape of a wheelie bin and information sheets about the plant.
Peter Dalley, Greenwich Council's Waste Services Manager, gave us a quick introduction to the MRF and we then donned high visibility vests, hard hats and a pair of headphones each (so that we would be able to hear him over the noise of the machinery) and made our way outside.
All the machinery is contained in a large shed, and entry was up an external flight of stairs. Our first view was as shown in the photo above with the conveyor containing mixed rubbish for recycling. (Greenwich council collect the rubbish to be recycled in either a blue topped wheelie bin or clear bags with everything in the one container – the householders don't have to sort anything out).
The rubbish first goes into a bag splitter which then feeds onto the conveyor leading to the Trommel Screen; a huge revolving drum 12m long and 3.5m in diameter which sorted out the heavier small items from paper and plastics. Our tour took us on a circuit following the various materials on their journey through the plant. Further round was a Plastics Automated Sorting machine; a very clever device that shines a strong light onto the items. A computer senses the infra-red wavelengths in the reflected light and sends a jet of air to deflect the plastic items on to another conveyor, while paper and other items fell through a hole.
Metal was sorted out with an Overband Magnet to lift off any ferrous metals and an Eddy Current Separator was used to send aluminium off the conveyor. It is because of this machine that the Tetra Pack juice cartons cannot be recycled; they are coated with a thin film of aluminium and the machine would send them into the container with the rest of the metal.
Some hand sorting was necessary to remove contaminants – and hence get a better price for the material: about £400 a ton for aluminium, £100 a ton for steel and only about £40 a ton for plastic. Plastic was sorted into various types by hand.
The sorted materials ended up in different hoppers prior to being sent on another conveyor to the baling machine. The materials are then loaded onto lorries for onward transportation to different locations for each commodity: paper stays in the UK, but plastic ends up in China – to be made into goods and then sold back to us!
After the tour, which lasted about half an hour, we returned to the room for free hot drinks and biscuits and an extensive question and answer session. It was a very informative visit and, if any members now wish they'd gone, I'm sure a further trip could be arranged.
» This article appeared in the March 2007 issue of SELMEC News.