Shredders expand their plastics footprint

Size reduction plays a role in the processing of numerous secondary commodities. Globally, investments being made to boost the recycling rate of plastic have resulted in the deployment of shredders in new applications and in greater numbers in established subsectors.

In the United States, dwindling legal export markets for plastics generated from end-of-life electronics there have caused Houston-based CompuCycle to develop a shredding, cleaning and sorting system designed to produce materials that can be recycled domestically.

“Plastics [are] becoming what some people may consider a focused material,” CompuCycle President Clive Hess says.

The information technology (IT) asset management company’s electronics recycling plant features two four-shaft shredders, a Quad Q100 and a Quad Q70, made by U.S.-based SSI Shredding Systems Inc. The processing line breaks down end-of-life electronics into its individual components.

More than 50 million tons of end-of-life electronics are generated annually worldwide, 20 percent of which contain plastics, according to SSI. These complex materials often contain hazardous substances such as brominated flame retardants and heavy metals. This not only makes them a challenge to recycle but also poses a significant risk to the environment and human health if not managed properly.

“That's why I truly do call it the ‘wow machine,’ because to see it from going up one conveyor belt and then turning into this next piece of material of really raw components of that steel, plastic, aluminum, copper and [printed circuit] boards, it’s just amazing,” CompuCycle CEO Kelly Adels Hess says.

“CompuCycle wanted a shredder versatile enough to handle bulk-fed loads of e-plastics originating from any processor out there,” adds Dave Fleming, vice president of sales and marketing at SSI. “Our SR500 Uni-Shear can hold up to 4 cubic yards of volume and make small, well-liberated output size, so it’s perfectly suited for this task.”

In November 2023, CompuCycle started up its e-plastics processing plant, which features a single-shaft Uni-Shear SR500 shredder and sink-float tanks that can separate e-plastics into their base components, such as polyethylene (PE), polypropylene (PP), polystyrene (PS) and acrylonitrile butadiene styrene (ABS) plastics.

“With being able to clean these plastics and to be able to separate these plastics, we can go now directly to [original equipment manufacturers],” Adels Hess says.

In Europe, Austria-based recycling machinery equipment provider Lindner-Recyclingtech GmbH says a system commissioned last year is helping a Lithuanian company recycle durable plastic “big bags” used in bulk shipping applications. The bags also are known as flexible intermediate bulk containers (FIBCs).

Since 2001, Lithuanian recycling company Virginijus ir Ko has been collecting, sorting and processing recyclable materials collected from industrial, commercial and agricultural sources. In 2023, the company commissioned a Lindner Washtech system designed to convert discarded sacks into pellets that can then be reprocessed back into big bags.

The Virginijus ir Ko recycling plant in western Lithuania in total processes around 35,000 metric tons of recyclables annually, with materials generated by the agricultural sector representing its largest fraction.

“We have been working with materials from the agricultural sector for years, including agricultural film and large amounts of big bag waste,” says Virginijus Skublickas, managing director of the recycling company.

“There was no recycling facility for big bags in Lithuania or nearby countries,” Skublickas adds of when the company was founded. “That’s what motivated us to invest in this area and recycle these materials locally. However, we soon realized that recycling big bags is a very complex issue.

“We didn't give up and found the right partner for this task in Lindner Washtech.”

FIBCs are usually made of PP plastic and are designed to be tear-resistant, hard-wearing and cut- and scratch-resistant.

“These are all properties that make the recycling process very demanding,” Lindner says, adding that the entire process chain for recycling big bags must be precisely coordinated to keep the fine particles content as low as possible and to guarantee a high level of material purity.

“As with many plastic recycling processes, the first shredding stage is the most important for big bag recycling,” says Tomas Kepka, head of sales in Eastern Europe for Lindner Washtech GmbH. “Thanks to its robust drive and safety clutch, the Micromat series shredder is particularly powerful and resistant to nonshreddables.”

The Micromat’s cutting system also is specially designed for big bag shredding, and special knives and an easily adjustable counter knife ensure high productivity.

In the subsequent process steps, the main focus is on gently removing any remaining impurities and drying the material.

Lindner says its “rafter” prewash system, with its low speed of approximately 60 revolutions per minute (rpm), is the ideal machine for removing contaminants such as stones and sand. Up to 90 percent of all dirt and contaminants can be extracted in this first washing step, according to the company.

In the subsequent processes, the prewashed and opened big bag flakes can be processed much more gently, avoiding material losses due to fine particles, Lindner says. Following cleaning, the material heads toward a drying unit and then the extrusion process.

“When drying big bag materials, we use the mechanical dryer from the Loop Dryer series,” Kepka says. “It is equipped with special tools that prevent high stress on the material due to friction. The dryer also has a frequency converter so that the speed can be adjusted and controlled accordingly.”

The FIBC recycling facility operated by Virginijus was commissioned in 2023 and has been producing what the company considers high-quality PP granulate for more than six months. The facility consists of a shredding and washing system, a process water treatment system and an extrusion system with odor decontamination.

“In Lindner Washtech, we found a partner who was able to offer a perfectly coordinated all-in-one design with many reference systems, from shredding to washing and drying,” Skublijckas says. “Lindner Washtech has been a reliable partner throughout the entire planning process, right through to commissioning and service. We would definitely choose a facility from Lindner Washtech again.”