A new waste treatment plant in Swindon, Wiltshire, is combatting the problems of near-full landfill and stalled recycling rates by combining refused derived fuel (RDF) and solid recovered fuel (SRF) facilities.
The combination of Swindon’s landfill capacity due to be reached in 2016, and a stagnant 50 per cent recycling rate led to Swindon Borough Council realising a need to evolve and change its waste strategy. The Council proposed a drive to increase recycling rates to 60 per cent and divert waste from landfill using the plant at its Cheney Manor site.
The RDF and SRF plant at Cheney Manor will divert 48,000 tonnes per annum of municipal solid waste (MSW) from the near-full landfill site, as well as creating a valuable fuel output.
The developer of the new plant, Swindon Commercial Services (SCS), a wholly-owned subsidiary of Swindon Borough Council, appointed Canadian firm Machinex Industries to provide the custom-made sorting equipment for the facility.
Due to the state-of-the-art nature of the plant, there are several sorting processes and therefore sorting machines which the waste needs to go through to meet strict RDF and SRF standards.
The Machinex-designed system includes a number of steps. The first involves separating a variety of shredded materials through the use of a trommel. This material will then be sorted using magnets to isolate ferrous and non-ferrous metals, before the non-ferrous metals are individually sorted. Finally, the material will be further shredded to RDF and SRF standards and then drying to SRF moisture standards.
The running costs associated with the plant are considerable so when sourcing the sorting equipment to be included within the facility, Machinex looked for the most efficient and cost-effective equipment.
As a result of this research, Machinex tasked British engineering firm, Magnapower, with providing the custom made magnetic sorting equipment for the Swindon facility.
To meet the strict standards for RDF and SRF fuels, an electromagnetic sorter is typically used to separate ferrous and non-ferrous metals. However, operating costs are high, with an electromagnet working across a 1500mm conveyor at a 400mm gap likely to use in excess of £100 per week of electricity (presuming a 16 hour day and a five day working week).
This significant running cost, along with high initial outlay and ongoing maintenance costs, led Magnapower to design a permanent over-band magnet based sorter. This new design provides a more even coverage across the conveyor, in turn producing a more consistent separation of material and a purer end product. In addition to providing better coverage, the high force deep-field magnets are also arranged in such way so as to reduce leaked magnetic flux, therefore increasing efficiency.
Due to the size of the material which the magnets will be sorting, Magnapower added an alternating pole discharge system to the over-band machine. This discharge system helps release small metal components which are trapped within steel, ensuring the sorted material meets the RDF and SDF requirements.
The newly-designed sorter has substantial financial benefits, most notably the potential £5200 annual reduction in electricity use due to the permanent magnet requiring no electrical power. The ongoing maintenance and start-up costs for the sorter are also considerably lower, resulting in a significantly better return on investment.
As well as financial benefits, the over-band magnetic sorter also provides health and safety and environmental benefits for staff working within the facility. Due to the absence of an electricity supply to the sorter, the risk hazards are significantly reduced. For example, the fire risk is lowered as there is no need for a high DC current supply or a transformer to be connected to the machine.
The environmental benefits result from the removal of the electromagnets, which require oil when in operation. This usual changing and disposal of the used oil presents several health and pollution hazards to staff within the facility and the surrounding environment.
Speaking about the new technology, Jonathan Ménard, Sales Engineer with Machinex Industries, said:
“The unique permanent over-band magnetic sorter Magnapower specified for the Cheney Manor facility is an excellent example of how innovation can help reduce running costs within the waste industry. The magnetic sorter not only effectively and efficiently sorts the shredded material, but it does so without electricity, ensuring running costs for the facility are kept as low as possible.”
Rob Jones, Magnapower’s Managing Director, said:
“We were delighted with the opportunity to work with Machinex Industries on the Swindon RDF and SRF facility. We are proud of the equipment we were able to supply for the facility and look forward to working with Machinex in the future.”
The Cheney Manor waste treatment facility was officially opened on 20th February 2014 by DEFRA minister, George Eustice. The plant became fully operational after the rotating drum drier was turned on last spring, completing the final phase of drying the material to produce RDF and SDF.