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Re: Processing/Managing CRTs and Computer Equipment
This is a belated response to two related inquires posted over p2 tech regarding the recycling/management of cathode ray tubes (CRTs) and computer equipment. I will first respond to Ms. Toy-Chen's inquiry, followed by Mr. Sullivan's inquiry.
Removing phosphor powder from CRTs
I could not find anything definitive but an Internet report (The recycling of Cathode Ray Tubes, Paul Lambert, 10/97) summarizes an investigation in recycling CRTs. It states that using a strong stream of water to remove phosphor powder from the front panel plate was not successful and that using a sponge cloth was very effective. The author also stated that, among the different techniques used for removing coatings from the cone, sandblasting was found to be most effective, but the inner conductive coating was more difficult to remove.
The author determined that there is a risk of generating dangerous projectiles when using certain disassembly techniques, such as using grinding or cutting wheels, and when the glass is smashed. He cautioned that the glass projectiles could pose safety concerns even if the handler is wearing a full protective mask, goggles and gloves. He stated that broken glass can penetrate gloves if the glass is not handled properly. One can electronically access this article at:
A glass recycler in Ohio stated that it was not necessary for his company to remove the phosphor coating. The phosphor-coated cullet was acceptable as feedstock by a CRT manufacturer. By the way, this recycler stated that he has contracts with three major CRT manufacturers that will only accept his CRT cullet because it consistently meets the stringent specification standards of the manufacturer. He is able to blend the cullet with various materials to meet the needs of the manufacturer.
There are a few web sites you may want to take a look at regarding the safety aspects of CRT phosphor powder. I did not find any standard guidelines or practices. A major concern of some phosphor powders may be that some contain toxic heavy metals, such as cadmium. CRT Phosphors also contain rare earth materials. There are a wide variety of non-cadmium containing phosphors for CRTs. Check out: http://www.phosphor.demon.co.uk/crt.htm (Phosphor Technology).
The rare earth materials are used as coloring agents and activators in phosphor powders. You may be able to obtain spec info in the Rare Earth Products Catalogue web site:
A major lamp manufacturer referenced a study conducted by the Industrial Hygiene Foundation of the Mellon Institute on a halophosphor powder they use in fluorescent lamp products. No adverse health effects were noted via, inhalation, ingestion, skin contact, or eye implant in the five-year animal study. The author stated that although antimony, manganese, yttrium, and barium, compounds incorporated in phosphor powders, are classified as hazardous chemicals by OSHA , they should not present a hazard in the event a lamp is broken.
Regarding use, I am aware of the phosphor powder from mercury lamps being used in speciality paints and in fertilizer products (after the mercury has been recovered from the powder).
It would appear that the primary impediment in recycling CRT cullet as feedstock in the manufacturer of CRTs and other glass products is the difficulty of removing contaminants from the cullet, and the variation in composition of CRTs, not only within tubes, but tubes produced by different manufacturers. The main culprit is lead:
2 - 3% , front panel
up to 24% funnel (back panel)
30%, neck of funnel
70%, frit, the material that unites the front and back panels
Many CRT manufacturers have introduced lead-free front panels and some are working on lead substitutes for the entire CRT. The article above suggests a need to effectively remove the front and back panels, not only for safety reasons, but to minimize contamination of the front panel glass by the high-lead funnel panel glass.
I don't have specific information on whether CRTs fail/pass TCLP. Anecdotal information suggest that the frit (70% lead) is leachable [apparently more so than the panel glass] and may fail the regulatory limit (TCLP) of 5 ppm (5 mg/liter), making it hazardous waste at the point of disposal. The Techneglass Home Page: http://www.techneglas.com/whatsnew/main.html
describes facts about frit and the way it is used in uniting the front and back panels.
For an information on the construction and operation of a CRT, see:
You may want to tap into the p2tech archieves. I recall dialogue on computer equipment and CRTs.
Large quantities of computers are being disposed of in solid waste landfills. The New York Times estimates that over 12 million computers wind up in landfills each year in the U.S. The Carnegie Mellon University (CMU) study (http:nsc.org/ehc/epr2/cmu_dat.htm) estimates that, by 2005, 55 million computers in the U.S. will be land filled. I don't have good information regarding state and federal programs specific to monitoring and handling discarded computer equipment. The USEPA has developed several initiatives, some in cooperation with states, academic institutions, and other groups for investigating electronic scrap.
As part of the USEPA -based Common Sense Initiative, a work group has been formed that is developing a strategy for removing perceived federal regulatory barriers to recycling CRTs. In addition to regulatory barriers, the work group will investigate economic, environmental and safety issues. Upon completion of the project, the work groups recommendations will be presented to the Computers and Electronics Subcommittee and the CSI Council. See:
CSI Computers & Electronics Sector: Electronic Product Recovery and Recycling (EPR2), Conference/Roundtable
The USEPA also funded two collection pilots for residential electrical and electronic equipment (http://www.nsc.org/ehc/epr2/pilots.htm). The National Safety Council, Environmental Center, has a web site (UPR2) devoted to
electronic product recovery and recycling (http://www.nsc.org/ehc/epr2.htm).
At the state level, the North Carolina Senate produced a bill (An Act to Require Retailers of Certain Goods to Take Them Back to be Recycled or Properly Disposed) requiring retailers to take back certain electronic equipment. including computers, batteries, fluorescent lamps, etc.
At the international level, the British government has enacted laws requiring electronic firms to organize the collection and recycling of computers (http://gurukul.ucc.american.edu/ted/COMPUTER.HTM). The Canadian government initiated a program whereby surplus provincial government computers are donated to Canadian elementary and secondary schools (http://gurukul.ucc.american.edu/ted/COMPUTER.HTM). The European Commission (October 9, 1997) issued a requirement imposed on distributors and manufacturers to take back electronic equipment. The requirements applies basically to all electronics and regulates the content of electronics, including a ban on lead, mercury, cadmium, and hexavalent chromium. (http://www.nsc.org/ehc/epr2/europe.htm)
The USEPA published a list (by state) of computer recycling/reuse centers (Electronic Reuse and Recycling Directory, Jan. 1997, EPA530-B-97-001) (http://www.epa.gov/epaoswer/non-hw/recycle/reuse/electdir/elect.pdf).
At the state, federal, local, and private levels, efforts are underway, or being developed, for the appropriate management of electronic equipment and scrap, with an up-front emphasis on reducing toxic components and designing equipment to facilitate their disassembly, handling, reuse and recycling. Some programs emphasize demanufacturing which includes electronic equipment collection, disassembly, selling, reuse or recycling. Attention is also being devoted to refurbishing, remanufacturing, and repair.
The lead of CRTs has been recovered by lead smelters. Some lead smelters also may used CRT glass as a fluxing agent. The primary focus seems to be on recycling CRT glass into new CRT products or other glass products (see reply to Donna Toy-Chen, above). Other recycling applications for computers:
Circuit Boards - precious metal recovery
Yolks, Transformers, Wire - metals
Aluminum and Power Supplies - metal, the power supply may be reused or refurbished
Fans - metal, reused or refurbished and reused
Hard and Floppy Disk Drives - sold as scrap; in many cases reused or refurbished
Plastic Cases - recycling
For further reading, see:
Electronics Industry Environmental Roadmap: http://www.mcc.com/env/roadmap/roadmap.disposition.html
Printed Wiring Boards/Assembly:
Electronic Products Recycling Study, Executive Summary:
The Remanufacturing Process:
Quantitative Assessment of Design Recyclability:
Desoldering Electronic Components:
Electronics Industry Environmental Roadmap: Displays:
In Ohio, the generator of a business disposing of electronic equipment must first determine whether the equipment is hazardous waste. In fulfilling this requirement, the generator may either use his/her knowledge or an appropriate analytical procedure (e.g. TCLP). If hazardous waste, the generator must dispose of the equipment to a permitted hazardous waste facility. If the equipment is destined for recycling, Ohio does not classify the equipment as hazardous waste. This facilitates the collection, transport, disassembly and recycling of electronic equipment. The generator is responsible for the appropriate characterization and handling of any component removed from electronic equipment that is disposed. For information on computer recycling in Ohio see: http://www.epa.ohio.gov/opp/recyc/comp-rc.html
As I stated above, I do not have a lot of data on analytical test conducted on CRTs or other electronic components. I am aware of some data showing that circuit boards and CRTs (see above, reply to Donna Toy-Chen) may fail TCLP for certain heavy metals.
I hope this helps.
Donna Toy-Chen Wrote:
An associate is in need of information related to the recycling of cathode ray
tubes. He is not on the listserve. Please forward any information to me and
I will pass it on to him. Thank you!
His questions are:
1. How does one remove the phosphor and other coatings applied to the
surface of a cathode ray tube (CRT) during a CRT recycling operation?
Should the operator wear any personal protection equipment? Is special
ventilation required in the work area? How much coatings (by weight)
will be generated per tube?
2. If these coatings are not completely removed, will they affect the
quality of the recycled glass or cause other problems (including ES&H
concerns during glass handling and disposal--if glass is not recycled)?
3. Are the removed coating materials recoverable/recyclable? If not, how
to dispose of them? Are they hazardous wastes? What are the hazardous
Charlie Sullivan Wrote:
Please provide your expertise/input to the following questions in the context of pollution prevention and related environmental stewardship:
1) How are state and regional environmental management programs monitoring and handling discarded computer hardware?
2) What are the accepted and proven recycling/reuse options for used and worn out computer equipment?
3) If it is being disposed, (land filled), is it defined as "hazardous waste and if so, how is the toxic content being determined?
4) Does anyone have documented TCLP data for computer equipment e.g. for lead content?
5) How do you segregate computer waste from other electrical components, ie. circuit boards and screens from televisions or related communications equipment?
6) Does anyone have specific rules or guidance on this issue?
Any, and all of your suggestions and information will be greatly appreciated, respond via the P2 Tech Net, or if you desire to:
Charlie Sullivan, IDEM/OPPTA, PO Box 6015, ISTA Suite 703, Indianapolis, IN 46206-6015. telephone 317-232-8174, or direct e-mail to: firstname.lastname@example.org. Thank You
Art L. Coleman, Jr.
Division of Hazardous Waste Management,
Technical Assistance Section
P.O. Box 1049
Columbus, Ohio 43216-1049