Shredding with a sustainable target

Thailand-based Indorama Ventures Public Co. Ltd. (IVL), a producer of polyethylene terephthalate (PET) and other materials tied to the PET supply chain, has pursued a strategy of global growth that has included considerable investments in recycled-content PET (rPET) production.

The company’s global presence in rPET production may be unmatched, with the building of an rPET production and supply chain a high priority of IVL Chief Sustainability Officer Yashovardhan (Yash) Lohia. Yash is the son of IVL Group CEO Aloke Lohia.

The company’s investments in PET bottle recycling have spanned several continents, with this year marked in part by an increased presence in North America. This June, IVL announced and then completed the acquisition of a former CarbonLite PET bottle recycling plant in Texas.

In Europe, the company operates plants in France, Ireland, the Netherlands and Poland, while it also has rPET capacity in Latin America in Brazil and Mexico.

Asia also remains a target of IVL rPET investments, with the company announcing or completing new PET bottle recycling capacity in India and Indonesia this year alone. (A plant also is under construction in the Philippines.) The investments tie into an overall global goal of being able to recycle 50 billion PET bottles annually.

Although IVL is exploring chemical recycling technologies, much of its current commitment relies heavily on the mechanical recycling of discarded PET bottles. That means shredding and other size-reduction methods are a crucial component of its large-scale recycling process.

The company chooses to keep much of its processing technology discretionary, but the IVL corporate communications department was willing to share some overall observations pertaining to its PET bottle shredding experience gained around the world.

IVL says it acquires and shreds PET bottles of all sizes, with its systems able to accept different sizes of PET bottles as part of the same production process.

Global standards and certification systems help ensure its recycling plants—including shredding and all steps before and after—produce desirable rPET. IVL cites “the Global Recycle Standard (GRS) developed by Control Union certifications” as “the most common one,” but also lists REACH [handling of chemicals I the EU]; OEKO-TEX and Standard 100 [pertaining to textiles and polymer fabrics]; SGS [pertaining to footwear materials]; and Ecomark [an Indian standard] as applicable at some facilities.

For the shredding process, baled PET bottles are the most common feedstock. The bales are weighed and “strictly inspected to meet quality criteria by our experienced staff as soon as they arrive at the factory,” says IVL.

The mechanical process “starts from opening the bales, sorting out other contaminants, including labels, with heat and washing with water to clean bottles before sorting other polymers from PET.”

The sorting process can be the most investment-intensive. “After sorting out compressed bottles from the bale, there are more than 20 steps to be taken. Key methods/technologies are deployed such as magnets and all-metal detectors, electromagnetic induction, label removing machinery, spinning sieves, near-infrared radiation sensors, spectrum cameras, sink and float water systems and centrifugal dryers.”

The sorted PET bottles are then fed for size reduction to make flakes. IVL states, “All caps and other lighter contaminants are removed by a floatation method. They are then hot washed with chemicals and dried before being melted into pellets and used as recycled material.”

Indorama does not disclose details of its shredding process, but a two-stage system most commonly relies on sturdy, slow-speed, high-torque shredders in an initial stage and higher speed granulators in the second stage.

A 2019 custom publishing piece prepared for United States-based SSI Shredding Systems provides a glimpse of how first pass high-torque machines have been a mainstay for United States-based high-density polyethylene (HDPE) recycler KW Plastics.

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KW credits shredders supplied by SSI with being able to “handle contamination that other shredders aren’t able to handle.” While bales of plastic bottles are supposed to consist of just that, the KW plant manager notes that contaminants can include “metal or big pieces of wood and other things in the bale that aren’t supposed to be there.”

After primary shredding and sorting, a two-pass system then often turns to high-speed granulators or grinders. A 2019 Recycling Today feature article portrays the role of such grinders at U.S.-based Mega Recycling & Compounding Services LLC.

That firm recycles clean polypropylene (PP), high-impact polystyrene (HIPS), polyethylene (PE), polycarbonate and nylon, among other plastics. In 2019, its fleet of seven grinders was creating recycled-content output that was compounded into resins to be molded into plastic parts by its sister companies Mega Compounding, Mega Molding and Mega Polymers.

Mega Recycling President Bret Garrison told Recycling Today in 2019 that the firm’s integrated recycling, compounding and molding operation “all starts with grinding. If we didn’t have the grinders, then the other three companies could not exist competitively in the marketplace.”