Finding a new leader in wood

Construction and demolition (C&D) waste makes up roughly 22 percent of the nation’s overall waste stream. Depending on the phase of a construction cycle, wood waste, in particular, can make up a significant percentage of materials hauled off-site to be processed. C&D wood extracted from a construction site often begins with trees and brush in the land-clearing phase, and as the project evolves, can include dry kiln lumber, plywood, oriented strand board (OSB), particleboard, pallets and trim.

For Lincoln Young of Rockwood Sustainable Solutions, based in Lebanon, Tennessee, wood recycling was supposed to be an add-on to his shingle recycling business.

“I was in the shingle recycling business with three locations in Tennessee, and we were asked to use our shingle grinder to process wood for a local city,” he says. “They had just purchased a downdraft gasification plant and located it at their wastewater treatment plant, and the city was looking for a feedstock.”

Finding a solution

Rockwood established a partnership with the city of Lebanon to collect and process wood for its feedstock needs. The plant was to use 20 tons of wood per day to make clean energy through gasification. “The gasification plant is what got us started in wood recycling, but we quickly found out there is more opportunity and more challenges than what we expected,” Young says.

Rockwood leaders thought they would collect wood, process it one time per month and feed the plant with little effort, equipment or capital.

“I remember when we first began wood recycling,” Young says. “We [very much] underestimated what we were getting into. Everything that Rockwood is doing today with wood was not intentional; it was all created in an effort to survive as a company.”

The main challenge Young says he faced when beginning wood recycling operations was sizing.

“What we found was that in using a horizontal grinder, we were able to grind the wood easily, but we consistently were creating too many fines or material that was smaller than ¾ inches,” Young says. “With gasification, you need airflow through the material, so a fine shred woodchip does not work. It is simply too dense and does not allow for a consistent end product.” In an effort to minimize the amount of fines being produced, Rockwood began trying to screen out the wood byproduct.

“Being new at wood recycling, I kept trying to screen out the fines only, [basically] everything under a ½ inch, and it was costing us a ton of money and [was] not efficient,” Young says.

“Then one day I decided to change screens and instead of trying to screen out fines under a ½ inch, I opened up the screens and began pulling out everything under 1 inch," he adds. “So, instead of creating an exact product that produced too many fines as a byproduct, Rockwood changed its equipment process and began making mulch.”

Young says this shift in the screening process was a turning point for Rockwood’s wood business.

“It was started in an effort to survive, but it quickly became our star product,” he says. “At first, fuel was 90 percent of our market, and within a year it was less than 5 percent of our end market by volume.”

In the process of creating fuel feedstock or mulch, Rockwood discovered it can produce a high-quality mulch product in a single pass if it uses the right equipment and screens on the grinder.

© Olaf Speier | stock.adobe.com

Diversifying leads to growth

According to Young, the company first started with a Peterson grinder, but the operation also has used Rotochopper and Vermeer equipment at times. Rockwood also has used a combination of screens, including flat-deck shaker screens, trommel screens and star screens.

“For Rockwood, our best combination resulting in the most production with the best quality is a horizontal grinder feeding [into] a star screen,” Young says.

Rockwood Sustainable Solutions found that a three-product star screen made the best product for its application—1-inch-minus product went to mulch, 1-inch to 4-inch product went to fuel and 4-inches-plus recirculated back to the grinder.

When Rockwood first started grinding wood, its feedstock was almost 99 percent pallet waste. As Rockwood began to grow, it began to transition into the C&D industry.

When the company first got into the wood recycling business, Young says he did not want to get involved in C&D recycling. However, he soon realized just how much wood waste can be generated from a construction job.

“I just didn’t like the idea of sorting in the beginning,” he says. “I wanted to have a streamlined process like our shingle collection where we did not have to handle a lot of waste other than wood.”

Needing an additional source of wood, Rockwood began putting roll-off containers on job sites for wood only, forcing source separation of the material. If the load was too contaminated, it was rejected.

“I laugh at our early thoughts on collections,” Young says. “Looking back, our business strategy was inexperienced to say the least. We struggled with wood collection in the construction industry because we thought we needed strict rules for separation. What we realized is that regardless of how much we screamed and yelled and fined, source separation just was not a 100 percent reality.”

He continues, “We had some job sites that would try, but there was never an uncontaminated load.”

The company grew tired of relying on those working at job sites to sort materials before dropping loads off, so, instead of trying to avoid sorting, the company embraced it. Young says he realized that source separation was not a sure thing on a construction site, so Rockwood had to change its mentality.

“Instead of avoiding sorting we encouraged commingled loads,” he says. “We changed our marketing entirely. In all lines of our business, we started selling ‘easy’ to the customer.”

Instead of trying to source separately, Young says Rockwood started taking all C&D materials.

“We were getting all the materials whether we wanted it or not, so we just found homes for the materials and started taking any C&D loads,” he says.

This diversity has aided Rockwood in its growth in the local market; however, it also has caused some additional challenges with wood waste. Instead of grinding all its wood product together because it was clean, it had to sort out wood by type. Currently, Rockwood does not sort using conveyors but instead sorts on the ground.

“We are still too small to justify a lot of sort lines, so for now we ground sort,” Young says. Rockwood can take any type of wood, sending the clean wood for mulch and the Grade B material to gasification at a plant owned by the city of Lebanon and operated by Aries Clean Tech. Young says the gasification plant has been an advantage for Rockwood because it creates an end market for a variety of wood types.

“For companies considering wood recycling, my advice is to make sure you have the end-market before you begin,” Young says. “Finding end markets for wood is much easier than other products, but you need diversity. You need several end markets to be successful long term.”

Young also says he wishes he knew more about the “power of collaboration” before he dove into wood recycling.

“If you are just getting started with wood recycling, hire out your grinding for the first few years [until] you know what you are doing. Find a local land clearer or partner with another grinding company but do your homework on your equipment and screening needs.”

Lincoln Young is president of Rockwood Sustainable Solutions in Lebanon, Tennessee. He can be contacted at lincoln@rockwoodrecycling.com.