Processing Of A Different Sort

Michael Fickes

Early processing plant design and engineering weren't so much flawed as limited by a lack of technology fitted to the task.

"The first plants were all straight lines and positive sorting," recalls Sean Duffy, chief operating officer of FCR Inc., Charlotte, N.C., a material recovery facility (MRF) builder and operator.

However, now that technology has evolved, processing facilities must follow suit. "To make it work, you have to purchase reliable equipment and operate it efficiently," says Steve Jones of Rader Resource Recovery Inc., Memphis, Tenn.

"If you charge $36 a ton tip fee to take in garbage, then the pro forma should be based on that. If you buy $2 million worth of machinery, relying on revenues from recyclables to pay the mortgage, then you've made a mistake."

The first recyclers had strengths in facility design, equipment purchasing or plant operation, Duffy says. To succeed as a recycler, however, he contends that a company must have strengths in each of those areas, not just one or another. "Doing all three has enabled us to weather the ups and downs of the marketplace," he says.

FCR has designed and built 10 MRFs in the Southeast. Currently, it operates those facilities with the help of 350 employees.

In developing a facility, FCR addresses business decisions as early as possible, at the time a municipality issues its request for proposal (RFP).

"The key is to make it simple," Duffy says. "You have to find ways to limit the amount of work they have to do. For example, we like to work in two streams: mixed paper fibers on the one hand and commingled glass, plastic and metals on the other. We design systems to separate those two streams, which enables the municipality to collect efficiently, by asking customers to do only two sorts."

Once the waste stream has been characterized, FCR engineers move into system design, which focuses on three goals:

* producing high-quality materials,

* running at high recovery rates with low residue and

* operating as efficiently as possible.

While efficiency means high through-puts, FCR balances that need with its recovery goals. "We like to design systems that promote recovery," Duffy says. "High recovery means we can sell more material. We typically run at 2 to 3 percent [recovery rates]. That comes from system design: Where to put the eddy current; where to put the air classifiers; what type of mixed glass processing system to use."

Those design decisions stem from research conducted early in the process. "While we're developing our response to an RFP, we're talking to the area glass companies and newspaper and corrugated mills," he says. "We have to understand those markets before we can formulate our bid and develop our design.

"In the glass industry, for instance, a company with optical sorting equipment can accept mixed glass aggregate," he continues. "If that isn't possible, then you might design a system to crush the mixed glass to a size used in the asphalt industry."

From there, FCR considers through-puts based on the municipality's volume. This determines the sizes of the in-feed and shipping areas and the sorting lines' lengths.

At FCR's newest plant in Memphis, Tenn., the city promised 100 tons per day (tpd). FCR engineers designed a 42,000-square-foot, $2.7 million facility to handle 125 tons per 10-hour shift - or 250 tpd when two shifts operate.

"You design the facility to handle the specified throughput in a single shift," Duffy says. "Smaller facilities like Memphis have different kinds of equipment needs. For example, here we use a single baler with the capability of doing plastics, metals and paper." The baler in the Memphis facility is a two-ram model, manufactured by Harris Waste Management Group Inc., Peachtree City, Ga., with a bale release and a bale separation door to accommodate multiple products and variable grades.

Larger FCR facilities - such as the one in Charlotte - move up the design chain to more sophisticated equipment, such as air classifiers, eddy currents, live storage bunkers, magnets and trommels for both negative and positive sorting lines.

To Automate Or Not To Automate According to Eric Herbert, vice president of Burrtec Waste Industries, Fontana, Calif., the keys to facility design lie less in advanced technology and more in smoothly integrated conveyor systems that present material to sorters in a way that makes sorting easier.

To that end, Burrtec recently purchased two sorting line systems from MayFran International, Mayfield, Ohio: one to sort paper and another to convey a commingled single stream of both paper and containers. "I have yet to see a piece of equipment other than a magnet that automatically sorts materials in the waste stream," Herbert adds.

To get the best price performance on a system over its operational life, Herbert concentrates on integrating proven systems, like sorting. For example, instead of requiring someone on a loader to push materials out of a bunker, Herbert's lines allow a sorter to choose a material to bale, push it onto a live floor and send it to the baler.

Automatic level controls that speed up or slow down conveyor speed based upon what has been fed into the system is useful, says Herbert. "This kind of system integration improves efficiency by making sorting easier," he says. "For the most part, it's really not complex or revolutionary."

Don't misunderstand. Herbert isn't a non-believer when it comes to technology, only a skeptic. "We're constantly looking at new equipment and ideas," he says. "We recently agreed to work with National Recovery Technologies [Nashville, Tenn.] on a project it calls an 'autosort system' which sorts paper out of a waste stream that contains everything."

Cutting Labor Costs Skepticism aside, advanced material handling equipment holds out the hope of controlling labor costs, which are by far the highest costs in the recycling mix.

Browning-Ferris Industries (BFI), Houston, has been investigating ways to automate material handling for years. "At one of our early plants in Florida, we designed a sort of eddy current, but it wasn't very effective," says Doyce Little, BFI's manager of the mechanical/electrical design group. "In the last four or five years, we've had more success."

BFI now uses a variety of advanced equipment. For example, some plants use automated rigid container sort systems with a magnet and a screen up front and an air classifier that blows lightweight plastics and aluminum off to a line - leaving the glass on the first line.

On the glass line, Little says, "We sort two colors, and the third is a negative sort." Recently, on the lightweight line, eddy current separators have been added to pop the aluminum up off the end of the line and separate it more completely from the trash, which falls off the conveyer's end.

The aluminum ends up on a conveyor that takes it into a silo with a bunker, where it can be pushed into the baler feed conveyor.

Little estimates that the eddy currents, which cost between $40,000 and $60,000, will pay for themselves in a year or two by eliminating the need for one to three sorters.

On the fiber side, BFI began installing old corrugated container (OCC) screens developed by Bulk Handling Systems, Eugene, Ore., about two years ago.

OCC screens can eliminate some manual sorting of compacted commercial refuse. "An OCC screen has a presort platform where the large contaminants are sorted out," Little says. "The small items fall through a large disk screen, and the corrugated goes off the end of the line in a negative sort.

"This has been a tremendous labor saver for us," he continues. "Instead of having eight to 10 people sorting corrugated, you might need only two to four people in the presort section of the line."

If an OCC screen eliminates five people, it will save $75,000 a year and pay for itself within a year or two, he says.

Little has seen demonstrations of two additional pieces of advanced equipment and purchased one of them: a bounce/adherence separator, which is a conveyor that tilts sideways and vertically and has shafts along its length with beaters that cause the belt to bounce up and down.

The bounce causes round objects to roll down the side or to the back, depending on the tilt setting.

Flat material such as newspaper adheres to the belt surface, which is made of a rough, somewhat tacky material.

"You don't get a 100 percent split this way, but you do get 80 percent to 90 percent," he says.

Expanding An Existing Facility The Spotsylvania County Department of Public Works in central Virginia operates 11 drop-off recycling facilities and one landfill. The largest drop-off center in Chancellor, Va., has been operating since 1988 and has grown popular with the 7,000 households located within a three-mile radius.

Center activity has grown to 3.5 vehicles per minute dropping off 50 tpd of household solid wastes and recyclables, including PET, HDPE, old newsprint, antifreeze, old oil, aluminum, glass, brush and wood waste.

In developing the most recent five-year spending plan for the county's recycling and landfill equipment, Doug Barnes, director of public works, included money to expand the Chancellor facility's capacity.

"We needed a piece of equipment that would bale more than just household wastes," Barnes says. The aim was to combine and compact the household wastes with large, bulky material - such as mattresses and sofas - in order to haul fewer loads.

"We also wanted to make it easier for residents to drop off materials," he adds. "Prior to the expansion, they had to drop off their trash in one spot and their large items in another. All of this led us to the idea of a pre-crusher, a beefed-up compactor with a steel wall that crushes the load first and then compacts it."

Barnes purchased two pre-crushers from Marathon Equipment Co., Vernon, Ala., for approximately $50,000 each and a $60,000 horizontal baler with side-load ejection to accommodate building constraints.

While the funds for the equipment came out of the tax dollars in the five-year plan, Barnes anticipates that the system will eventually pay for itself by increasing the center's current $130,000 per year in recycling revenues.

Also included in the plan were funds for a $250,000 tub grinder to mulch brush and wood. Given the space limitations at the existing facility, Barnes looks for multi-task equipment.

For example, its $150,000 Caterpillar (Peoria, Ill.) IT-18 front-end loader with rubber tires has multiple features, including a grappling hook to load brush into the tub grinder, a bucket attachment to load mulch into a truck and a snow plow to clear the facility's driveways during the winter.

Processing equipment continues to evolve as manufacturers modify their equipment to meet the needs of facilities with growing capacity demands and limited space.

At a basic level, the right equipment can make the sorting job easier and faster by lessening the need for manual labor. At the business level, equipment selection can be tailored to a operating plan for efficiently moving different kinds of waste streams and processing various products.

In the end, however, today's processing managers continue living a life of trial and error while writing the chapters on the next generation of recycling.