backlight whose bulb contains mercury.
Old CRTs have lead in their monitor
glass. Even that humble iPod is stripped of
its battery, which, I’m told, can be tricky
because bending them can have unfortunate consequences. Toner and ink are also
put aside for proper disposal.
Once the safety hazards have been
removed, the remainder of the device,
known as the carcass, is tossed into a large
cardboard box. Or if it’s something too big
to fit, such as a photocopier, it’s moved
aside until it’s time to meet its doom.
As they’re filled, the boxes are scooped
up by one of many forklifts zooming
around the plant, and deposited onto a
conveyor belt. That photocopier we left
lying around is ushered to an elevator; its
destination is the same, a giant shredder
that munches the equipment into chunks
(the cardboard boxes and pallets are rescued and reused). Those chunks are fed
to a second shredder that chews them up
some more, and its output goes to a third
shredder that emits pieces about two inches in size.
Okay, so now we have little pieces, but
they’re composed of all sorts of different substances. Next comes the sorting process.
First, the output stream passes over a
screen. Little pieces of wire and other small
objects ( 4 to 6 percent of the material) fall
through, and are sent to a smelter that cleanly melts them down and incinerates plastic
coatings without polluting the atmosphere.
Next, magnets snatch up any ferrous
metal from the mix. That accounts for about
40 percent of the material, and it, too, ends
up in a smelter.
Finally, clean aluminum is extracted by an
eddy current separator, a device that uses each
substance’s conductive properties to sort out
the valuable metal.
Now we have a mish-mash of bits of plastic, old circuit boards, and components left
to deal with. According to Sims, although
the company is currently running a pilot
project to separate and recycle certain
kinds of plastic, for the moment the
bulk of leftovers are sent to the smelter,
incinerated (and emissions scrubbed to
contain airborne toxins), and the remaining metals recovered.
Back at the Sims plant, the job isn’t
over. The company not only has to safely
break down the recyclables, it has to
ensure that the residue of its work doesn’t
pollute the environment. Even the dust in
the air is collected and sent off for processing to recover metals, and the drainage
system is isolated to ensure that anything
unpleasant can be intercepted before it
escapes. Employees are regularly tested
as well to make sure they haven’t been
exposed to bad things.
The bits and pieces deemed toxic are
then sent off for proper destruction or
reclaiming (believe it or not, the mercury
in those backlights can be recovered
When this “mining” operation is complete, the result is environmental savings on
multiple levels. Reclaimed metal is metal
that doesn’t have to be dug out of the
ground; that doesn’t mess up human, plant,
and animal habitats; and doesn’t have to
be extracted from ore, leaving huge piles
of waste. And equipment that is recycled
doesn’t litter up our already overtaxed land-fills, and doesn’t have the opportunity to
leach chemicals into soil and ground water.
And it also gives us nice empty drawers
and closets to fill up with mor~e of our for- merly adored electronic toys.
Permission to make digital or hard
coPies of all or Part of this work for
Personal or classroom use is granted
without fee Provided that coPies are
not made or distributed for Profit or
commercial advantage and that coPies
bear this notice and the full citation
on the first Page. to coPy otherwise,
to rePublish, to Post on servers or to
redistribute to lists, requires Prior sPe-
cific Permission and/or a fee.
© acm 1091-556/08/0600 $5.00