CRT Recycling
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CRT Recycling
Robert Debok
Derek Janiak
Edwin Lacen
Robert Slipkovich
University of South Florida
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CRT Recycling
Have you ever given any thought to what happens to all of the old electronics you throw
out? Whenever you trade up to that new plasma TV, what do you do with your old one? If you
just throw it away, it ends up as e-waste. E-waste—all unused and discarded electronics—has
become a growing epidemic around the globe. Because an ever-increasing pace of advancement
in technology leads people to upgrade electronic items even quicker, the accumulation of e-waste
increases dramatically. A lot of e-waste is sent overseas to developing countries for dumping or
burning.
One e-waste item being discarded today is the CRT (cathode ray tube) monitor/television.
A CRT-type display utilizes a large glass tube coated in phosphorus and an electron gun to create
an image (The Anatomy of a CRT Monitor (and CRT TVs), 2011). The process of recycling
CRTs involves:
1.
Gathering CRTs
2.
Deconstructing the CRTs, which in turn involves
○
Circuit board processing
○
CRT glass processing
Gathering CRTs
Wrapped CRTs Ready for Recycling
Source: Affordable Computers, Inc. (2011)
CRTs may be collected a number of ways before they undergo the recycling process. In
many instances, the CRTs are donated to or collected by different agencies relative to a
consumer’s location. Sometimes, facilities are willing to come and pick up CRTs and in others,
individuals have to drop them off at the facility. Online,
you can easily locate a nearby facility willing to accept old
CRTs for recycling process using websites like
allgreenrecycling.com and floridawaste.com.
When they are ready to be shipped, CRTs are
stacked one on top of the other in short stacks. They are
then shrink-wrapped tightly and sent to the appropriate
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nearby factory to undergo the recycling process. At the location, the CRTs proceed to the
necessary conveyor belts to undergo their deconstruction.
Deconstruction
Along the conveyor route, various stations are setup that allows monitors to be taken
apart. Gaylords, or large barrels, are placed along the conveyor route for easy placement of
monitor parts by factory employees.
One of the first steps in breaking down a monitor for recycling begins with removal of
cords and connectors on the unit. These items may be sold or simply recycled at a scrap yard.
Buttons and knobs that may be on the monitor are then removed, as well as any plastic bases or
peripheral parts of the unit.
Sorted Recyclable CRT Components
Source: Creative Recycling. (2011)
Once the exterior of the unit has been
checked, an employee will remove the case from
the main CRT assembly, called a jug. The case is
composed of a back portion called the bucket and a
front, flat surface known as a bezel (The Anatomy
of a CRT Monitor (and CRT TVs), 2011). The
monitor will be checked for contaminants and any
recyclable plastics. Recyclable plastics are only
allowed to be made up of one plastic (they cannot be a mixture). If there are recyclable plastics,
they are placed in a container.
The wires that connect the CRT to the plastic bucket are clipped and sold for scrap. A
dense bundle of copper near the electron gun of the CRT, known as a yoke, is sold for scrap and
is shipped to a scrap facility (Andela Products, Ltd.).
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Circuit Board Processing
A CRT has various circuit boards inside, depending on their use. In PC monitors, the
circuit boards decode data from the computer and control what is displayed on the screen. CRT
TVs have additional circuit boards for channel tuning and audio processing. After circuit boards
are removed from their CRT housings, they are shipped to a processing facility that specializes in
recycling and disposal of circuit boards. Unfortunately, a circuit board processing facility cannot
recycle all of the boards they receive. In many cases it is not cost effective to handle the boards
and in other cases the boards contain harmful materials such as mercury. Circuit boards that do
not get recycled are disposed of and ultimately end up in landfills (eHow, 2008).
After the processing facility has removed boards they cannot recycle, they mechanically
remove components from the boards such as capacitors, integrated circuit chips, and resistors.
These components may be inspected and saved for reuse, but often they are discarded. Once the
components have been stripped from the circuit boards, the circuit boards move on to be crushed
and ground into smaller pieces. Next, the boards are immersed into a solution of muriatic acid
and nitric acid (or equivalent substitute). The acid dissolves the metals present in the circuit
boards. After all the metals have been dissolved, the solution is filtered and the remaining waste
is neutralized, rinsed thoroughly, and discarded.
Then, the processing facility begins the task of extracting the precious metals from the
acidic solution, using chemicals called precipitants. Precipitants react with a solution and cause
dissolved solids to reform. For example, to extract gold—the primary metal a refiner wants to
recover from the solution—the processing facility uses hydrazine hydrate to cause gold to
precipitate and fall to the bottom of the solution. Then the solution is filtered and the gold is
rinsed and melted into bars. Various other chemicals are then added to extract metals such as
palladium, copper, and lead in the same process.
Once all metals have been extracted and melted into bars, they are sold back to
manufacturers for reuse in many consumer products. The remaining solution is neutralized
thoroughly by chemical treatment and discarded (Shor International Corporation, 2011).
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CRT Glass Processing
CRT Glass Cullet
Source: Close the Loop, LLC. (2011)
Because the CRT glass contains lead (jwolf, 2010), it must undergo a separate resmelting process before it is used again. After the electron gun and external metal strip has been
removed from the CRT jug, the jug and its internal
metal frame is taken to a material processing
operation. For example, ANDELA, a manufacturer
of recycling systems, developed a CRT Processing
System consisting of a Breaker, metal removal, and
screening and conveying equipment (Andela
Products, Ltd.). The Breaker crushes the glass and
separates the metal components from the glass,
placing them into two separate containers. The
crushed glass, called cullet, is then shipped to a
separate facility to be re-smelted. Smelting involves extracting a metal from an ore using heat
and a chemical called a reducer. The reducer is usually a carbon source, and is used in the
smelting furnace to remove the oxygen from the metal so that the pure metal can be extracted; in
this case, the lead in the glass (Wikipedia, 2011b). After smelting, the glass can then be used by
CRT manufacturers to make new CRT glass or for other glass products (Andela Products, Ltd.).
Once all reusable material has been extracted through these various processes, the
materials are sold back to manufacturers. Gold and copper may be resold to manufacturers of
printed circuit boards to use in the traces and contacts of new boards. Glass can be reused to
make any number of glass products, including newer televisions and computer displays.
Conclusion
With a proper recycling method, harmful toxins and gases can be kept out of our
environment. If not, e-waste will continue to accumulate in dumps and landfills, typically in
developing countries. In dumps, toxins leach into the soils and have the potential to contaminate
the water supply of developing countries. Sometimes e-waste is burned, which is worse because
the process releases toxic gases into the air (Wikipedia, 2011a). It seems like a faraway problem,
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but suppose the disposal processes done in those countries occurred in your neighborhood; could
you ignore it then?
However, if e-waste items are recycled, not only will these harmful environmental effects
be prevented, but the need to constantly extract raw material from the environment can be cut
down. Companies can save money by just using the recycled material instead of needlessly
spending capital on mineral extraction. Also, wouldn’t it be nice to able to breathe in clean air
without having to worry about toxins and pollutions that can shorten your lifespan or give you all
sorts of diseases? Indeed, it’s safe to say that the greatest benefit of e-waste recycling would be
the safeguarding of the broad world we call home.
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Bibliography
Andela Products, Ltd. (n.d.). Andela Products - Andela CRT Recycling System. Retrieved
October 9, 2011, from Andela Products, Ltd. Web site:
http://www.andelaproducts.com/products/crt3.html
CNET. (2011). How Your CRT Monitor Is Recycled. Retrieved October 9, 2011, from 5min Ltd.
Web site: http://www.5min.com/Video/How-Your-CRT-Monitor-Is-Recycled259733686
eHow. (2008, March 12). How to Deal With PCBs When Recycling Electronics | eHow.com.
Retrieved October 9, 2011, from eHow.com: http://www.ehow.com/how_2241331_dealpcbs-recycling-electronics.html
jwolf. (2010, November 20). How Are CRT (cathode ray tube) Monitors Recycled? Retrieved
October 9, 2011, from greencitizen.com: http://greencitizen.com/blog/?p=37
Shor International Corporation. (2011). Refining gold & platinum with safe nitric acid substitute
and muriatic acid. Retrieved October 9, 2011, from Shor International Corporation Web
site: http://shorinternational.com/subzeroinstr.php
The Anatomy of a CRT Monitor (and CRT TVs). (2011). Retrieved October 9, 2011, from
PCTechGuide.com: http://www.pctechguide.com/crt-monitors/the-anatomy-of-a-crtmonitor-and-crt-tvs
Wikipedia. (2011a, September 21). Electronic waste. Retrieved October 9, 2011, from
Wikipedia, the free encyclopedia: http://en.wikipedia.org/wiki/Electronic_waste
Wikipedia. (2011b, September 25). Smelting. Retrieved October 9, 2011, from Wikipedia, the
free encyclopedia: http://en.wikipedia.org/wiki/Smelting
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Images
Affordable Computers, Inc. (2011). [Image of wrapped CRTs]. Recycling.jpg. Retrieved from
http://www.affordablecpus.com/images/Recycling.jpg
Close the Loop, LLC. (2011). [Image of workers working on CRT glass]. Workers at the CRT Recycling
Plant. Retrieved from http://www.closetheloop.com/images/300_crt_glass_recycling.jpg
Creative Recycling. (2011). [Image of sorted CRT components]. Electronics Recycling .jpg. Retrieved
from http://www.crserecycling.com/images/Electronics%20Recycling%202.jpg