Page 659 - Materials Chemistry, Second Edition

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630 Waste Management Practices: Municipal, Hazardous, and Industrial

TABLE 22.5
Primary Components and Composition of a Monitor

Glass Components
Panel glass. The panel or screen makes up the front of the CRT and accounts for two thirds of the CRT mass. In late
model CRTs, the panel glass contains barium oxide instead of PbO
Funnel glass. The rear portion is referred to as the bell or funnel. Funnel glass is leaded glass; most of the Pb in a CRT
is in the funnel glass
Neck. The neck is the straight glass tube that surrounds the electron gun(s). The neck is made of leaded glass
Solder glass. The solder glass or frit is used to seal the CRT. Frit is 85% Pb
NonGlass Components
Banding. Metal banding reinforces the CRT. It must be removed prior to recycling
Electron gun. The stainless-steel electron gun creates the electron beam
Shadow mask. The shadow mask is a metal screen that focuses the electrons on the back of the panel
Yoke. The coils of copper wire around the neck of the CRT are known as the yoke; the yoke is an electromagnet that
deflects the electrons to the proper position on the panel
Phorphor coating. Special compounds adhered to the inside of the panel; they produce light when struck by the
electron beam
Source: Reproduced with kind permission of the Materials for the Future Foundation, San Francisco, CA.

When wastes are recycled rather than disposed, generators must comply with the regulations in
40 CFR Part 261 to determine if the wastes are to be regulated under RCRA. These regulations are
based on the assertion that recycled secondary materials (a material that is potentially a solid waste
and a hazardous waste) fit into one of five categories. The categories relevant for CRTs are:
● Spent materials. This includes obsolete computers, even if they still work.
● Commercial chemical products. This can include unused circuit boards.
● Scrap metal. If recycled, even scrap metal that is hazardous is exempt from hazardous
waste regulations.
The most relevant types of recycling activities regarding CRTs are:

● Reclamation.
● Speculative accumulation. If materials are kept on-site for longer than a calendar year,
they can be regulated as speculative accumulation.
By considering the category of material and type of recycling activity for a particular prod-
uct or material, Part 261 is used to determine whether that material is a solid waste when recy-
cled in that fashion. If it is determined to be a solid waste, then it could possibly be a hazardous
waste.

22.5.1 HAZARDOUS WASTE
As discussed in Chapter 11, hazardous wastes are either listed or are characteristic hazardous wastes
(ignitable, corrosive, reactive, and toxic). The RCRA regulations require the solid waste generator
to conduct the waste determination. Research conducted at the University of Florida shows that
CRTs usually fail the TCLP for toxicity. The California Department of Toxic Substances Control
confirmed that the CRTs in computer monitors, television sets, ATMs, and other devices contain
TCLP-soluble Pb concentrations that classify them as hazardous waste when they are discarded
(Harris, 2001; SVTC, 2001). Monochrome monitors do not usually exceed the TCLP limits and
could probably be segregated from color monitors for disposal. California law considers nonfunc-
tioning CRTs from televisions and monitors to be hazardous waste.