The most annoying aspect of recycling—and one of the biggest hurdles to its
widespread adoption—is having to separate paper, glass, and plastic before they
hit the curb. New recycling machines are changing that. With single-stream
recycling, recyclables go into one bin, which a truck delivers to a
materials-recovery facility. There, a largely automated system of conveyor
belts, screens, magnets, and lasers separates materials so that they can be sold
to metal and plastic recyclers and paper mills.
While the system isn't perfect—its high-speed operation can lead to
contamination from broken glass—the simplicity of it means households actually
recycle more. "If people want a higher recycling rate, it has to be convenient,"
says Mr. Miller, of the National Solid Wastes Management Association. "And I
think the technology is only going to improve."
1) Tipping floor
Dump trucks deliver mixed recyclables to the facility and pile them on the
floor. The driver checks to make sure no oversize objects, such as a car engine,
are in the mix.
2) Drum feeder
A mechanical claw grabs a handful of material from the tipping floor and
drops it into a spinning drum, which evenly distributes the recyclables onto a
conveyor belt.
3) Initial sorters
Workers extract plastic bags, coat hangers, and other items that might jam up
the line, as well as anything that won't fit through the sorter.
4) Large star screens
A series of offset star-shaped discs called star screens—originally invented
by the Dutch in the 1950s for sorting tulip bulbs—lift out corrugated cardboard.
Smaller items fall through the screens and continue down the conveyor belt.
5) Second sorters
As the material travels away from the star screens, human workers positioned
along the line remove smaller contaminants. "This is where we pull out people's
wallets," says John DeVivo, a co-owner of Willimantic Waste Paper.
6) Medium star screens
Three smaller star screens lift out different grades of paper, which makes up
two thirds of recycled material at Willimantic Waste Paper. Plastic, glass, and
aluminum fall through the screens and roll back down onto the main belt.
7) Glass sorter
Glass, which is heavier than plastic and aluminum, falls through the star
screens and lands in bins below. A separate system of conveyors moves the
material to a different area on-site, where it's ground into a coarse sand for
shipment to glass recyclers.
8) Magnetic metal sorter
A 3,900-gauss magnet passes above the conveyor and attracts anything
magnetic—usually only 4 percent of the total recyclable material.
9) Eddy current separator
A magnetic field induces electrons in aluminum to create a magnetic field of
their own, known as an eddy field. By interacting with the machine's magnetic
field, the eddy field pushes aluminum off the main conveyor onto another
one.
10) Infrared lasers
At this point, only plastic remains. Infrared laser beams shine on the
plastic items, and a sensor detects the signatures of different grades of
plastic. Strategic puffs of air separate the recyclable and non-recyclable kinds
into different bins.
11) Baler
Every 70 seconds, the last machine on the conveyor belt makes a bale of
recycled paper, plastic, cardboard, or metal. A single bale of paper is five
feet by four feet by three feet and weighs approximately one ton.
12) Landfill
Whatever items are left—jar lids, shoes, Happy Meal toys—go into a landfill.
In Willimantic Waste Paper's single-stream system, that's about 5 percent of the
material it collects.
As a waste sorting system manufacturer, we can provide recycling soring
machine, hydraulic baler machine, paper baler machine, plastic baler machine and
so on.
