World-Class Sorting

Photo courtesy of Eco Plastics

When it comes to plastics sorting, one of the most technologically advanced companies is the U.K.’s Eco Plastics Ltd., based in Hemswell, in the county of Lincolnshire.

The company specializes in sorting and reprocessing mixed plastics, particularly bottles. Eco Plastics also produces food-contact-quality recycled polyethylene terephthalate (PET) pellets and is currently the only company in the U.K. capable of doing this.

All of this is done at a bottle sorting and plastic processing facility that is one of most impressive you’ll find in Europe or beyond. The Hemswell plant processes 150,000 metric tons of mixed postconsumer plastics each year, sourced primarily from waste contractors, material recovery facilities (MRFs) and local authorities throughout the U.K. and Ireland. From those mixed plastics, Eco Plastics produces 11 different plastic outputs, including recycled PET pellets.

Managing Director Jonathan Short says one of the main reasons Eco Plastics built the unique sorting system it has stemmed from the need to ensure quality in the products the company produced, particularly because its feedstock can comprise a mixed bag in terms of material consistency or quality.
 

Photo courtesy of Eco Plastics

Sorting Steps
Eco Plastics was founded in 2000, but it wasn’t until 2006 that the company built its first plastics processing line that was similar to the process in place at the company’s Hemswell plant today. That original line was expanded over time; however, the company’s original facility burned down in 2009 and was rebuilt in 2010. Further expansions of its processing capacity were completed in 2011, Short says.

Today the company’s Hemswell plastic bottle sorting facility separates mixed plastics utilizing an arrangement of 20 multifunction Titech sorters. The machines are capable of performing near-infrared and optical sorting simultaneously, “so you’re combining the two technologies in one machine,” Short says. The plant is capable of processing 24 metric tons per hour, and its equipment sorts the incoming plastics by color and by polymer.

Short says the machines can detect, for example, if a container is a natural milk bottle, sending that bottle where it needs to go using a gust of air. Or, it can detect whether the container is a HDPE bottle of household cleaner. Once detected, the material is again moved in the correct direction using small blasts of air.

“We have 20 [sorters] in total and decided to introduce the high-specification multifunction units to afford us full flexibility,” Short explains.

The PET bottles segregated at the plant are granulated, dry-washed and then sent on within the facility for washing and extrusion into food-contact-grade recycled PET pellet. Currently, all other segregated plastic streams are either shredded and washed or baled in their current form and supplied to the company’s large portfolio of external reprocessing partners.

One offshoot of Eco Plastics’ work is its involvement with Continuum Recycling, the company’s award-winning joint venture with Coca-Cola Enterprises Ltd. of the U.K. Continuum’s centerpiece is its high-end extrusion machine, which has been approved to make a food-contact-grade material from plastic scrap and has passed Coca-Cola’s validation program, so that the recycled PET pellets can be used to make bottles for Coca-Cola in Great Britain, Short says.

The company recently celebrated its first year of operations by reaching 500 million bottles processed since the facility was opened in May 2012.

While that extrusion equipment has gotten a lot of attention from within the industry, Short says the success of the Continuum joint venture depends heavily upon the processes that occur well before the material ever hits the extruder.

“We go through four different sort processes before we even go into the wash process,” explains Short. “By going through all of those sort processes, we ensure that all of the cross-polymer contamination, such as the mixed plastics mixed in with the PET, is kept to an absolute minimum.”

The hot wash process for the sorted granulated PET bottles takes care of half of any cross-contamination, Short says. Then the half-inch flake is sent through an ultra-high resolution flake sort module to remove any cross-contamination that remains. The module uses color sorting technology in the form of two color sorters from Bühler Sortex of Uzwil, Switzerland, and five near-infrared detection sorters from Titech, based in Norway. The module is designed to process 8 metric tons of flake per hour.

“We take out any colors that shouldn’t be in there,” says Short, “and we also have a polymer sort.”

Short describes the flake sort module as a “major investment in ground-breaking technology that delivers a food-grade PET flake for the extruder.”

Short says this equipment works the same way as that used in the initial sort, “the main difference being that with flake there are many more pieces and, therefore, ultra-high resolution units are used.” Short says the flake sorting technology in use at Eco Plastics makes approximately 530 million quality decisions per hour.

“The business we operate in is a parts per million business,” Short observes. “By the time we get to this stage, we need levels of contamination at less than 10 parts per million in our process.”

Overall, Short says, there are literally thousands of quality checks on the sort and wash/extrusion line in place at Eco Plastics. He estimates there are more than 4,000 input checks conducted daily throughout between the sorting, washing and extrusion lines. “It’s all about quality control,” he says.

“That is what you’ve got to get to in order to ensure that you then have a world-class pellet,” says Short. “You’ve got to get all of your pre-processes right first, then it will work.”

The company’s finished flake product then can be extruded through either extrusion process—the one in place at Eco Plastics or the Continuum equipment—depending on the customers’ requirements. Both extruders are capable of producing a food-contact-grade recycled pellet, Short says. The extrusion lines are the final piece in the process that makes the actual food grade material, Short says.
 

High Demand
Of the 150,000 metric tons of mixed plastics that ECO Plastics processes each year, Short says, “the most PET we would expect to get from our mix would be around 65,000 metric tons per year.” The company’s two extrusion machines offer a combined 40,000 metric tons of extrusion capacity, he says.

When it comes to feedstock supply, Short says the U.K.’s collection system has grown quickly but remains fragmented.

“Consumers don’t get a consistent message about the types of materials that should and shouldn’t be collected,” according to Short.

Furthermore, he says, certain collections systems in the U.K. aren’t really suitable for the type of MRF where they’re processed, leading to lower-quality secondary commodities.

“There’s no point in putting mixed material through a 10-year-old MRF,” he says.

He says the bales received at Eco Plastics, for instance, may contain many different types of plastic and oftentimes also a high amount of paper, glass, grit and dirt. “That’s generally because the quality of the collection systems or the quality of the MRF doesn’t equate to the quality of the material that the MRF is expected to process,” he adds.

Short says positive changes are underway in the U.K, though, including a quality action plan that should lead to improvements in material quality.

In the meantime, though, Short estimates that the U.K.’s plastic reprocessing capacity currently stands at about 300,000 metric tons, half of which is supplied by Eco Plastics.

He says growing demand for PET means the country needs more recycling facilities in future years. “More collection and processing is required for PET,” says Short, “as demand will outweigh supply for some time,” he says. Short says the U.K. demands approximately 90,000 metric tons of food-contact-quality recycled PET pellets, but the current supply is only 40,000 metric tons right now.

Part of the reason for this gap, Short says, is the need for better collection programs and for material of a higher quality. “Those are two of the main drivers for a more successful recycling economy.”

Short says he is unaware of other plastic sorting lines similar to his own. He attributes this largely to historical necessity in the U.K. “We’ve grown up with poor quality; that is why we’ve built up the sort line we have.”

But, he adds, other regions, including North America, may increasingly need systems like the one at Eco Plastics if current trends are any indication. “Quality is in general on the decline, and companies need to build plants like ours.”

The author is managing editor of Recycling Today Global Edition and can be reached at lmckenna@gie.net.