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Consistent high-quality recovery

efficient sorting2

In 2015 the Scottish Government introduced the Household Recy­cling Charter with an associated code of practice. It was born out of concerns raised about the number of collection systems in different local authority areas, as well as the quality of recyclates which were collected and could subsequently be recovered.

With concerns about contamination, the aim was to introduce consistency into the market, reduce confusion among house­holders and capture high-quality recyclates.

Councils were asked to commit to aligning their collection systems to that under the charter. One of the main themes is a move away from commingled dry recyclate collections to a dual-stream approach, where fibres are col­lected separately from containers.

Levenseat in central Scotland wanted to be able to help its cus­tomers deliver their commitment by offering an option for dry recy­clates that promised to recover glass, metals and plastics that are of a consistently high quality.

The company’s new container MRF has a throughput of 13 tonnes an hour with an annual capacity of around 50,000 tonnes. It officially started operations on 12 March and will recover clean separated streams of glass, metals and plastics for supply to repro-cessors.

efficient sorting1

efficient sorting1

Designing the facility

The plant has been designed to efficiently sort mixed household containers. Having a clear under­standing of customers’ needs was a critical part of designing a facil­ity that could accommodate them.

The charter envisages glass being collected separately but, for logistical reasons, a number of authorities in Scotland include glass with metal and plastics.

Taking this into consideration, Levenseat began by laying out the system requirements. Some material would be collected in plastic bags so, to have a consistent feed into the plant, it required a suitable bag splitter and feed system.

Because this was a new collec­tion system for householders, there might also be a high level of non-target material making its way in to the waste stream. The company chose to have a pre-sort cabin immediately after the initial in-feed, where such items, as well as plastic film, could be removed.

From here the waste passes under an electromagnet to recover steel prior to entering a Machinex three-stage glass screen, which processes the glass into 50mm cullet and separates it out.

The materials then move over a 2m-wide eddy current to separate aluminium and non-ferrous metal from the plastics. Both streams are further processed through the quality control cabin to remove any non-target material that may have been missed in the pre-sort. There is scope for further separation of Tetra Paks if required.

The facility also houses a Machinex multi-purpose, two-ram, high-capacity baler to allow the efficient baling of the metals and plastic before export from site.

“A flexible plant which can accommodate a range of material mixes while focusing on the quality of outputs.”

Selecting a supplier

When it came to choosing an equipment supplier, it was impor­tant that there was a clear under­standing of the project ’s requirements. Key aspects were: plant throughput and flexibility; recovered recyclate quality; pro­cess efficiency; operational relia­bility and availability; capital cost; and a short delivery time.

Machinex, which was already working with Levenseat on its materials recycling and fuel preparation plant, was chosen. It had proved to be a company that was not scared to think outside the box, so Levenseat was confident in its ability to deliver a solution that would align with require­ments.

Future-proofing

Within the design, Machinex has included a number of upgrades designed to further improve the quality of recovered materials and enhance their value. These include further glass clean-up and separation of plastics by polymer type.

These upgrades will be incorpo­rated once Levenseat has devel­oped operational experience of the input mix and a clear understand­ing of off-taker requirements.

As Scotland moves towards having one consistent national system for household waste collec­tion, further changes are expected in how waste is separated at source. The company has there­fore focused on delivering an effi­cient and flexible plant which can accommodate a range of material mixes while focusing on the qual­ity of outputs.

Angus Hamilton is managing director of Levenseat

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