The increasing need for new and modernised MRFs

Increasing numbers of ageing MRFs are being updated to meet today’s more challenging requirements, and new MRFs are being designed and built differently to those of the past. Ruben Maistry, UK Sales Manager for STADLER, explains why and how.

As the recycling industry adapts to shifting market demands and tougher legislation, materials recovery facilities are having to change. This essential modernisation process necessitates more than incremental improvements in technologies. Every fundamental step in an MRF’s operations – sorting, processing, storage, and shipment – has to be thoroughly assessed to ensure the facility’s optimum performance, not only now but also in the future. And because waste streams differ in composition and volume from one place to another, MRFs must be tailored to the waste-management needs of their own particular location and clients.

A brief look at recycling trends helps explain the evolving emphasis of work conducted at MRFs.  The relative values of recycled commodities are changing, contamination levels of kerbside-collected materials are increasing, and the composition of single-stream recyclable materials is altering. Municipal solid waste (MSW) is a good example. As consumers move from print- to digital news media, the once-huge proportion of newspaper in the overall material stream is declining. As more shopping is done online, the proportion of cardboard in the overall material stream is increasing. And as manufacturers reduce the weight of plastic containers and aluminium cans, MRFs have to sort and process greater numbers of these items to produce a bale of marketable material.

On top of this, the once-easy ‘solution’ of making waste someone else’s problem by shipping it to foreign shores is disappearing. The short-notice introduction in 2018 of China’s National Sword regulations had repercussions for waste-exporters globally, and now other countries are also expected to tighten their waste-import restrictions.

Solving this complex matrix of challenges is the specialisation of STADLER UK, a subsidiary of STADLER Anlagenbau GmbH in Germany. STADLER has sometimes been inaccurately thought of as a consultant but is in fact much more. In addition to designing, manufacturing, and assembling automated sorting systems and machinery for the recycling industry, STADLER also designs, builds, and upgrades world-class MRFs. To date, the company has built or optimised 85 MRFs, most in Europe and six in the UK.

One of these modernisation projects, completed in the UK last year, provides an insight into STADLER’s approach. This multi-million-pound project replaced an existing facility. The objectives were to increase capacity and improve output quality.,. To achieve these goals STADLER implemented a phased plan typical of its approach with other projects.

At the start of a project, STADLER looks at the MRF’s infeed composition, desired output, and existing processes. Examining process-flows identifies bottlenecks and how to eliminate them. Phase 1 also examines mass balances and machinery choices. The machines installed by STADLER at this plant included one PPK and two STT2000-8 ballistic separators, two trommel screens, 12 NIR (near-infrared) optical sorters, nine material bunkers, three magnets, two eddy current separators, six sorting conveyors, and two balers, as well as dust-extraction and HVAC.     

In Phase 2, STADLER’s in-house project management team is forwarded a Project Handover which contains detailed information relating to the contract and customer requirements. With this information, the in-house designers create a detailed 3D design of the plant. Because this design shows the complete steel supporting structures and walkways, the client is given a complete overview of the plant and STADLER can conduct an Access, Lifting and Maintenance review (ALM) along with the client. The ALM looks at accessing, lifting and maintaining key components such as drive motors. Carrying out the ALM during the design phase eliminates the need to modify steel work once the installation has been completed. Once the layout has been approved by the client, drawings are submitted for the start of manufacture and supplier equipment is ordered. Electrical information is passed on to STADLER’s in-house electrical team, where electrical panels are manufactured, and operating programmes written.

The third phase is installation, typically involving a combination of machinery from STADLER and other manufacturers, which STADLER project-manages on-site. All installation activities are carried out by STADLER employees holding all necessary health and safety and training qualifications.

Phase 4 is ‘cold’ commissioning of the plant without material. During this phase, the STADLER commissioning team is introduced to the project and carries out various activities such as testing the different modes of operation, pre-setting frequency invertors, making final adjustments on supplier equipment, and training staff members. ‘Hot’ commissioning is performed shortly afterwards with an agreed volume of input material. During this process STADLER assesses the areas that are critical for material flow, checking if transition points need to be optimised and if all machinery is operating according to specifications. Once these criteria are met, STADLER then runs the plant with the contracted throughput as stipulated by the client. 

Finally, Phase 5 is Performance Testing and Take Over. An independent contractor is appointed to verify the performance of the plant and to ensure that all contractual requirements are met. STADLER personnel are still on-site during this phase, to assist the client with day-to-day operations and clarify any queries the independent contractor may have regarding material analysis. Following the performance testing, the results are summarised and presented to the client in a final Take Over Report. Upon confirmation of this report, an Acceptance Certificate is signed by STADLER and the client.

Throughout these phases, all design, manufacturing, installation, commissioning and performance testing utilises STADLER personnel with the exception of the independent contractor. Keeping all activities in-house streamlines efficiency by ensuring less interface management.

As a result of this replacement, the new facility now has the capacity to sort 17 tonnes per hour of mixed recyclable material, producing fractions of news and pams, mixed paper, cardboard, HDPE, PET, mixed plastics, film, non-ferrous and ferrous materials, and scrap metals. One key strategy, removing cardboard from the process as soon as possible (with a STADLER PPK unit located after the first pre-sort cabin) has significantly benefited the rest of the line. Capacity has been raised from 65,000 to 75,000 tonnes per year.

The improvements achieved by this modernisation project and many others like it, and the growing number of new turn-key MRFs built by STADLER, are essential steps in the journey towards creating a circular economy. And at the same time as benefiting the environment, they are enhancing each plant’s commercial competitiveness.

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