Leading plant designer and builder, STADLER UK Limited, was appointed by Viridor as one of two main contract partners for the major transformation of the Masons MRF. In its tender documentation for the upgrade, Viridor specified TOMRA Sorting Recycling’s sensor-based sorting solutions.  Having already worked together on several projects around the world, STADLER and TOMRA worked in close collaboration from the very early stages of the tender enquiry to ensure the plant and equipment met Viridor’s specific requirements. 

By investing heavily in the plant upgrade, Viridor has been able to transform its operations, increasing capacity from 65,000tpa to 75,000tpa (equivalent to 17 tonnes per hour). The plant is now operating at full capacity and at optimum processing levels. Output quality has also improved considerably, thanks to the new TOMRA equipment installed during the upgrade. 

World-class sensor-based sorting solutions 

The infeed material for the Masons MRF is comingled dry mixed recyclables from Suffolk County Council. Glass is not included in the Council’s collections. 

On arrival at the plant, the infeed material is first processed using brand new mechanical separation equipment, including a dosing drum, a STADLER PPK ballistic separator, a screening drum, STADLER STT 2000 ballistic separators, overband magnets and eddy current separators. Following mechanical separation, the material (apart from fibre) then goes through an air separation process before arriving at the newly installed TOMRA AUTOSORT® optical sensor-based sorting units. 

Prior to the upgrade, three TOMRA optical sorters were in place at the MRF. These were replaced by 11 new TOMRA AUTOSORT® units.  As one of the existing units was only four years old, TOMRA simply uploaded the latest software and it was good to go. 

All 12 AUTOSORT® units are flexible in their design and can be programmed to target different materials. At Viridor Masons, the units have been programmed to 

  • sort and recover mixed fibre (cardboard, mixed paper and newspapers and pamphlets)
  • sort mixed plastics by polymer into high purity single stream plastics (PET, HDPE, hard plastics, film, pots, tubs and trays)

The AUTOSORT® system is a highly ultra-compact versatile sensor-based sorting system which can be used across a vast range of material sorting applications.  The system, which can be easily integrated into any existing or new sorting processes, brings together the very latest in TOMRA’s technologies to deliver advanced accuracy of complex sorting tasks at high throughput rates. Capable of separating materials which are difficult or even impossible to separate using conventional technologies, AUTOSORT® consistently delivers high performance sorting accuracy across all target fractions – even in the most complex of applications.

Once the infeed material at Viridor Masons has been processed by the relevant AUTOSORT® units, it is given a final quality control check before being baled ready for transportation to end customers, all of whom are UK-based.  Any material that is left once all the target fractions have been recovered is sent for energy recovery or to landfill. 

Delivering operational benefits 

With the new mechanical and sensor-based equipment in place at the MRF, Viridor is now reaping a number of operational benefits, including: 

  • Increased throughput – the plant can cope with a higher tonnage of infeed material (10,000 additional tonnes per annum) 
  • Market-leading purity of target fractions, for example, achieving 98.5% purity on newspapers and pamphlets and 95%+ for polymers such as PET, HDPE and mixed plastics  
  • Cost efficiencies resulting from the plant running at full capacity 
  • Reduced risk of plant downtime 
  • The ongoing maintenance contract in place with TOMRA to ensure equipment continually works at optimal efficiency levels  
  • Flexibility in design – the equipment can be reprogrammed to cope with changes in the infeed material stream 
  • Futureproof solutions – the equipment is designed with ever-changing market needs in mind 
  • Cost savings derived from sorting PET and HDPE – previously this material was sent to Viridor Rochester for reprocessing but now it can be reprocessed on-site, cutting the carbon footprint and saving on reprocessing costs

Steven Walsh, Sales Engineer at TOMRA Sorting Recycling, comments: “Masons is now among the most highly automated plants in the UK. We were delighted to work with STADLER on this project, having already worked with them on a number of other projects nationally and internationally. Prior to the refurb, this Viridor site could only sort mixed plastics for further processing at the Rochester PRF and it was extremely manual sorting focused, with hand sorting used for all cardboard and refined paper grades. Now though, by integrating TOMRA equipment and benefitting from TOMRA’s technical expertise, the plant’s advanced automated capabilities mean Viridor can capture superior quality materials ready to feed back into the circular economy.” 

Benjamin Eule, Director at STADLER UK Limited, adds: “Our role was to decommission the existing plant and supply and install a full turnkey solution for the newly upgraded plant which would meet the required material specification needed at the time for Viridor. It was one of the quickest turnarounds we’ve ever worked on. It only took around three months from the initial discussion to signing contracts and then, once contracts were signed, we were on-site five months later to undertake the installation.  It took two weeks to decommission the plant and everything was brand new other than one TOMRA optical sorter which TOMRA simply uploaded the latest software onto as it was only a few years old. The installation – including demolition of the old equipment – took 80 days in total. 

“We installed new steel work, conveyors and all electrical components required for the process. We managed both the cold and hot commissioning processes.” 

Viridor Recycling Director, Derek Edwards, said: “This is by far the largest investment in a UK MRF in recent years. Viridor is heavily focused on developing opportunities to put quality recycling materials back into the economy where they belong. This starts with viewing waste as a resource, rather than rubbish, and, thanks to Suffolk’s commitment to recycling, and our investment in the Masons MRF, we are well positioned to make the most of the county’s recycling opportunities and to sell that material onto UK-based end customers.”

Mr Edwards added: “The Masons investment plan has been specifically designed not only to achieve greater capacity but to match the quality of its output with market requirements. The plant now has the same infeed material as before, but the upgrade has resulted in us being able to cope with an additional 10,000 tonnes of material per annum. We are delighted with the performance of the plant and its equipment since the upgrade was completed.” 

Viridor Masons’ Upgrade in numbers

  • £15.4m investment 
  • 1,950m² premises  
  • 10,000 tonnes additional capacity per annum 
  • 111 conveyors (1,124 metres running through the plant)
  • 12 TOMRA AUTOSORT® units 
  • 98.5% purity on newspapers and pamphlets
  • 95%+ for polymers such as PET, HDPE and mixed plastics  
  • 80 days to fit the new equipment 
  • A team of 50 professionals worked on site during the refurb work