Wood recycling is cornerstone of new Tallahassee C&D facility

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For better than four decades, the Williams family, owners of Marpan Supply, Inc., have been in the container services business in and around the Tallahassee area. And for the last 15 years or so, steady area growth meant that waste stream has been heavy with construction & demolition (C&D) debris. Seeing that, prompted Kim Williams, son of Marpan's owner and founder, to question the logic — or maybe even the sanity — of burying all that potentially valuable material. As time went on, dissatisfaction with the status quo continued to eat at him, eventually leading to the formation of a sister company, Marpan Recycling. Today, a significant portion of the Class III waste which Williams recognized as valuable is, indeed, being recovered in a $5.5 million state-of-the-art facility, which has as its centerpiece, a three-stage wood recovery/recycling system featuring a Morbark Predator shredder, trommel and vertical mill grinder.

Sensible Approach
As mentioned, much of what ultimately drove Kim Williams to establish Marpan Recycling was environmentally-driven. He genuinely wanted to assure his customers and the public that material dropped onto its tipping floor would be properly handled. There was also an economic incentive; the recycling operation seemed like the logical extension of their existing business.

“For a long time, I've felt that this material was too valuable to be throwing away,” says Williams. “In light of the current energy situation, and the price of raw materials and commodities spiraling upward, that's never been more true. So that was one motivation: to responsibly handle and recycle Class III waste from throughout Leon County. However, I also saw it as a way to vertically integrate the new company with our hauling business.”

That integration, he says, ensures the peace of mind in knowing that the 200 tons per day of material which the plant is currently taking in has largely been collected by them, and is coming across their scales, in their trucks or containers, to their processing system.

“It's more a question of control, than anything,” he says, “Because we are not ending our day at a landfill somewhere, if we have a problem of any kind, I know we can resolve it in our own facility, with our own people. And fewer trips to the landfill means not only are we recovering more material, but we are also saving fuel and reducing diesel emissions from the trucks. It's positive all the way down the line.”

Making a Good Thing Better
Primary materials taken in at Marpan include concrete, dirt, steel, wood and cardboard. However, Williams says they are also looking into the possibility of recycling carpet, carpet pad and plastic.

“But we first needed to refine our current process before expanding outward, and we are already starting to do that,” he says. “In early May, we conducted tests with our own material and received DEP approval to open the last week of that month. Since that time, we have identified specific areas that were slowing down the process, worked with one of our major equipment suppliers, made the necessary ‘tweaks' and have dramatically increased throughputs.”

Material dumped onto the tipping floor, is picked up by excavator and fed onto an apron conveyor that, in turn, feeds a General Kinematics vibrating finger screen which separates material into sizes over and under 6-inches.

“The finger screen is really the key component in this first step,” says Williams. “It allows us to remove all the smaller material that has value, then sends the larger waste on to hand-sorters who pull any recyclables from the stream. Non-recyclables are routed to a compactor for eventual landfilling. Obviously our goal is to make that volume as small as possible and we are getting there: we currently recycle better than 70% of the material that passes through here. At peak, that's 140 tons of material each day that will not be wasted in the ground.”

Urban Wood Waste
An efficient, effective recovery of wood from within the Class III stream was integral to Marpan's business plan and, to do that, Williams knew he would have to go against some long-accepted norms.

“In putting together my plans for the wood waste portion of the facility, I looked both here and in Europe and discovered that Europeans handle their C&D debris far differently than we do. They are not constrained by a fear of multiple-processing, choosing often to pre-shred material in a low-speed, high-torque shredder, then pass it along for screening and a final grinding. Here, everyone tries to talk you out of such an approach, saying you can't handle material more than once and still be efficient. I saw benefits in the way the Europeans were doing it and started leaning in that direction.”

A visit to Morbark's annual Demo Days event resulted in Williams meeting with Mark van der Galien, Managing Director of Holland-based OBMtec, who related the success his customers were having using a Morbark Predator as a first-stage shredder in advance of a secondary grinder. That approach struck a chord with Williams and he began to put together his plan to recycle the area's urban wood waste.

Miserly On Energy
There were a number of factors that helped shape the design of Marpan's wood recycling system, including a need to make processing as efficient as possible, and a desire to remain energy-conscious in every phase of the operation. Feeding material into a Predator shredder, routing it to a trommel screen and sending the resultant material to a Morbark Model 1500V vertical mill for final processing seemed to meet those criteria well.

“Going that route definitely made sense from a fuel usage standpoint, given that the Predator burns about 12 gallons/hour versus 50 gallons/hour with a larger horizontal grinder. In addition, knowing that boiler fuel was going to be one of our final products, I went to a number of potential customers and found that they were concerned about the amount of dirt in the material they were getting; the trommel would address that issue nicely.”

For the final phase, Williams chose an electric-powered Morbark vertical mill with a pair of 250 Hp (460V) electric motors to generate the 3-inch chip product needed by the area plants. Not only would an electric unit consume less energy, Williams thought, it would also greatly reduce maintenance demands.

“With an electric grinder,” he says, “we don't have to deal with the coolant system of a diesel engine, we don't have to change oil, we don't have the power draw off the engine that it takes to keep itself cool. A shot of grease every now and then is all this machine demands. Generally speaking, a V-mill's biggest shortcoming is its difficulty handling long or broad material; that issue is resolved by first running the wood waste through the Predator. Hands-down, this is the most efficient way to do what we are doing.”

Going Even Greener
With several months of operation under their belts, Marpan is focusing its efforts primarily on C&D waste/debris and landclearing debris. While a potential contract with the City of Tallahassee to process its green waste could change that somewhat, Williams says there are advantages to staying with the C&D debris.

“The advantage of urban wood waste is that it has only 15% moisture content, while a tree has 55%. A company has to first expend the energy needed to remove that moisture, so the BTU output per ton is a lot higher with the urban wood waste. The downside is that it has metal and dirt in it, which can be a problem for some boilers. However, we have magnetic head pulleys at several points in our system, so that issue is essentially resolved.”

Predatory Possibilities
Still another key to Marpan's wood waste system's success is in its flexibility. Acceptably-sized material can be fed directly into the V-mill. Other material can be pulled directly from the trommel. And the use of the Predator opens the company up to new products and markets.

“The Predator, beyond shredding wood waste, has the ability to process a broad range of materials including white goods, tires, assorted scrap, and so on. It is a mobile unit and we definitely plan to capitalize on that mobility, both here in our facility and elsewhere. Otherwise, to keep with our low-fuel consumption focus, it would also be a fixed electric unit.

Ultimately, says Williams, once Marpan Recycling gets volumes up even further, they envision purchasing a second Predator and converting their existing unit to a stationary electric machine. Evolution, it would seem, is critical to ensuring continued success.

“Our goals when starting up this company were simple: keep as much C&D material out of the landfill as possible; turn that waste into a usable, marketable product; and do so in as environmentally-friendly a manner as possible. A lot of planning, coupled with outstanding equipment and support from both Morbark and Sherbrooke, has helped make that happen. But we still feel we've only started to scratch the surface of what's possible here. Our system is rated to process up to 500 tons a day and we have plenty of room onsite for future expansion. The possibilities for what we can do are just about endless.”

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