The (return) path to healing

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This article originally appeared in the July 2022 issue of Resource Recycling. Subscribe today to access all print content.

Paper recycling is a given in most communities, and it has been that way for decades. However, in May 2019, the city of Lexington, Ky. suspended curbside paper collection.

Several factors influenced this decision. The changing recycling stream now includes lighter containers (mostly plastic) and smaller paper and OCC, which can be more difficult to sort.

The realities on the ground at the Lexington Aging Materials Recovery Facility (MRF), owned and operated by the Lexington-Fayette Urban County Government (LFUCG), have compounded the problem, with more plastic wrap and other stringy materials entering the flow and enveloping themselves in the installation. screen configuration almost ten years old.

Additionally, contamination rates were high and the MRF struggled to meet stricter standards for mixed paper bales as a result of China’s national sword policy.

With insufficient national end markets for existing materials and with little space to store bales, LFUCG was stuck. The production of marketable paper products had become too laborious to be economically viable.

“Residents wanted to recycle paper even after the suspension, as evidenced by the use of yellow bins scattered throughout the city,” said Tracey Turner Thurman, director of the City of Lexington/Fayette’s Waste Management Division. County. “People were upset, but the city was determined to find a way to get back to paper recycling.”

Ultimately, Lexington succeeded in bringing fiber collection back into the program, allowing curbside collection of the material to resume in May 2022 after a three-year suspension.

The key was to re-equip the LFUCG MRF, and here’s how it went.

The planning process

In early summer 2020, Lexington worked with consultancy Resource Recycling Systems (RRS) to identify what was needed to upgrade the MRF and bring the community back to curbside paper recycling. By early spring 2021, Lexington, RRS and equipment supplier Machinex Technologies had finalized design plans for the fiber line upgrade.

A $4.2 million upgrade was needed at the LFUCG MRF, which operates one shift per day and processes 20 tons of material per hour to serve a population of more than 320,000 people. As part of the annual budget process, funding for the upgrade was requested and approved by the Mayor and the full council of Lexington.

MRF personnel had several tasks to manage in preparation for the demolition and installation. Lexington had to hire separate contractors to install new electrical chutes, relocate lights and sprinklers, and install a new overhead door and ramp, among other projects.

Even after successfully preparing for the start of Machinex’s on-site work, problems arose. Since the upgrade was a modernization, several issues with the old equipment were discovered, including needed repairs to the moving floor bunkers, a worn conveyor bed frame, and electrical connections.

Clear communication and quick budget approvals kept the project on schedule.

The refurbished OCC screen in the Lexington, Ky. MRF.

The new system

The renovation significantly reworked the way materials move through the Lexington MRF, with the innovation augmenting the process at several points.

Material is fed into the new system via the existing drum feeder, which ensures a constant feed rate of material to the pre-sorting stations and to a refurbished OCC screen, designed with larger shafts to help to avoid excessive wrapping of film and other stringy materials. It also reduced disc spacing to increase capture of small OCCs.

Then the material passes through a scalping screen, a primary ballistic separator, a fines screen and a polishing ballistic separator.

The new scalping disc screen helps reduce packing and better direct glass to a new glass breaker/fines filter. The main ballistic separator separates the large papers from the rest of the stream, and the second (polishing) ballistic separator separates the 2D materials from the 3D materials and also removes the fines that were not separated at the glass/fines screen.

“Ballistic separators work to further separate paper from containers and, compared to replaced disc screens, are much less prone to material wrapping,” said Christopher Hayes, senior project manager at Machinex. “Ballistic separators provide more consistent sorting throughout the life of the machine and require less downtime for maintenance due to fewer wear parts and the elimination of disc changes necessary for rubber disc screens to maintain consistent sorting.”

The fibrous material from the new primary ballistic sorter is transferred to a new dual-ejection optical sorter designed to further refine the flow to produce a salable product. The fiber cleaning optical sorter has two settings: one in which small brown fibers are isolated and another in which high and low quality fibers are extracted, allowing customization according to end market requirements.

The new system not only refines the fiber flow, but repeatedly captures missed materials, such as containers, back to the start of the container line. The conveyor on which the non-fibrous material falls from the fiber cleaning optical sorter can send the material to the bin or to the container line, depending on the position of a diverter.

Additionally, both manual fiber sorting lines have chutes for containers, sending this material to the container line.

“The LFUCG MRF equipment upgrades not only enable the return of paper recycling, but will have positive impacts on the quality of sorting materials, including paper, glass and containers,” said Kerry Sandford, Senior Engineer at RRS.

A new optical sorter at the plant separates PET containers, cartons and other containers.

Containers from the aforementioned container return conveyors and those from the Polishing Ballistic Separator pass through a new dual ejection optical sorter where the flow is split into 1) PET containers, 2) cartons and other fibers, and 3) other containers. This optical sorter, funded by a grant from the Carton Council of North America, allows MRF to accept cartons and create grade 52 aseptic packaging and gable-end carton bale, a product that MRF has never produced before.

In addition to grade 52 bales, the MRF has the ability to produce grade 54 (mixed paper) and grade 56 (sorted residential paper) bales from incoming mixed paper and currently sells material to mills that produce cups paper, fabrics, packaging, paper prints and other paper products.

“The Carton Council is thrilled to be part of this upgrade to restore paper recycling, including the valuable fiber obtained from food and beverage cartons,” said Jason Pelz, Vice President of Projects. recycling at Carton Council North America and vice president of sustainability for the United States, Canada, Central America and the Caribbean at Tetra Pak. “Paper recycling is more important than ever to ensure there are enough raw materials available to make new sustainable products. This optical sorter helps capture valuable materials and reduce contamination of other material streams. »

Back on track

Originally a building constructed for steel processing, the Lexington MRF has seen several upgrades. It moved to a single stream in 2010, added glass cleaning in 2012 and recent fiber and container line upgrades went live in April 2022.

“Technology continues to advance recovery with optical sorters, AI robotics and new innovations in processing,” Sanford said. “The ever-changing waste stream requires an ever-changing recovery and treatment system.”

Due to Lexington’s commitment to providing the best possible recycling services to their residents, local stakeholders have risen to the challenge of an evolving stream and changing markets. Improvements to the MRF have resulted in the recovery of high-quality paper and board, as well as a more efficient material recycling system overall.

Holly Halliwill is a consulting engineer with RRS and can be contacted at [email protected]

This article originally appeared in the July 2022 issue of Resource Recycling. Subscribe today to access all print content.

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