United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-94/047 May 1994
EPA Project Summary
Mercury Usage and
Alternatives in the Electrical and
Electronics Industries
Bruce M. Sass, Mona A. Salem, and Lawrence A. Smith
Many industries have already found
alternatives for mercury or have greatly
decreased mercury use. In some appli-
cations, however, the unique electro-
mechanical and photoelectric prop-
erties of mercury and mercury com-
pounds have made replacement of mer-
cury difficult. This study was initiated
to identify source reduction and recy-
cling options for mercury in the electri-
cal and electronics industries (SIC 36)
and in measurement and control in-
strument manufacture (SIC 382). The
project reviewed sources and use of
mercury to identify trends in pollution
prevention for mercury use throughout
the U.S. economy. Regulatory trends
encouraging mercury pollution preven-
tion were examined, and current prac-
tices in the electrical and electronics
industries were reviewed in detail to
identify potential source reduction and
reuse options for mercury. Industrial
and economic data suggest that the
quantity of mercury used in electrical
and electronic control and switching
devices is significant. Opportunities
have been identified to replace mer-
cury-containing devices. For applica-
tions where mercury cannot be avoided,
recycling, mainly by vacuum retorting,
is commercially available.
This Project Summary was developed
by EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to announce
key findings of the research project
that is fully documented in a separate
report of the same title (see Project
Report ordering information at back).
Introduction
The objective of this study was to iden-
tify source reduction and recycling options
for mercury in the electronics industry. To
accomplish this objective, the sources and
uses of mercury in the U.S. economy were
reviewed and regulatory trends encourag-
ing mercury pollution prevention were ex-
amined to provide a background for a
detailed review of the electronics industry.
Current practices in the electrical and elec-
tronics industries (SIC 36) and in mea-
surement and control instrument
manufacture (SIC 382) were reviewed in
detail to identify potential source reduc-
tion and reuse options for mercury. Use of
mercury-bearing chemicals as preserva-
tives in paint has been eliminated, and
mercury use in many other industries has
declined. The electrical, electronic, and
instrument industries have, however, found
mercury difficult to replace because of the
unique electromechanical and photoelec-
tric properties of mercury and mercury
compounds. The project tabulated data
on mercury use throughout the U.S.
economy to quantify historical use. Re-
cent regulations were reviewed to indicate
possible future trends for mercury use.
Current practices in the electrical and elec-
tronics industries were analyzed and po-
tential source reduction and reuse options
for mercury were identified.
This study was conducted as part of the
U.S. Environmental Protection Agency's
(EPA) effort to develop pollution preven-
tion options for Resource Conservation
and Recovery Act (RCRA) wastestreams
that have been difficult or expensive to
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treat. Mercury-containing RCRA wastes
are difficult to treat reliably by conven-
tional techniques such as solidification/
stabilization. This project was undertaken,
with the coordination and cooperation of
the Office of Solid Waste, to help define
pollution prevention technologies for mer-
cury-containing RCRA problem wastes.
Pollution prevention is the use of materi-
als, processes, or practices that reduce or
eliminate the creation of pollutants or
wastes. Pollution prevention should be
considered the first step in a hierarchy of
options for reducing the generation of pol-
lution. The next step in the hierarchy is
responsible recycling of any wastes that
cannot be reduced or eliminated at the
source. Wastes that cannot be recycled
should be treated in accordance with en-
vironmental standards. Finally, any wastes
that remain after treatment should be dis-
posed of safely.
Mercury Economic Data and
Regulation
Recent Patterns of Mercury Use
Mercury for domestic use in 1990 came
from domestic mines, sales of surplus from
government stocks, imports, and waste
recovery. Mercury was produced as the
main product of the McDermitt Mine and
as a byproduct of eight gold mines in
Nevada, California, and Utah. The
McDermitt Mine has since been closed.
Market expectations indicate a continuing
decline in both the production and use of
mercury and an increased reliance on re-
cycled mercury.
Common secondary mercury sources
include spent batteries, mercury vapor and
fluorescent lamps, switches, dental amal-
gams, measuring devices, control instru-
ments, and laboratory and electrolytic
refining wastes. In 1992, commercial sec-
ondary mercury reprocessors produced
176 metric tons of mercury. The second-
ary processors typically use high-tempera-
ture retorting to recover mercury from
compounds and distillation to purify the
contaminated liquid mercury metal.
The main uses for mercury are in chemi-
cal production, particularly chlorine/caus-
tic manufacture; electrical and electronic
components; and instruments and related
products. Recent mercury use patterns
are indicated by Table 1. As shown in the
table, the use of mercury has declined in
response to regulatory pressures, particu-
larly in paints and chemicals. The full re-
port presents more detailed data on
mercury use in the electrical and electron-
ics industries indicating that, although to-
tal mercury usage has declined over the
past decade, use in electrical and elec-
tronic devices (other than batteries) has
remained fairly constant.
State and Federal Regulations
Solid wastes containing leachable mer-
cury above the Toxicity Leaching Charac-
teristic Procedure (TCLP) limit (0.2 mg/L)
and certain source-specific wastestreams
are regulated at the federal level under
RCRA (40 CFR261.10). Mercury air emis-
sions are regulated at the federal level
under the National Emissions Standard
for Hazardous Air Pollutants (NESHAP)
(40 CFR 60.50). States are beginning to
enact legislation to limit the quantities of
mercury in non-RCRA-listed wastes en-
tering municipal waste disposal facilities.
Mercury Treatment Standards
Under RCRA
From the mid-1980s to early 1990, the
EPA collected and evaluated process per-
formance data to identify Best Demon-
strated Available Technologies (BDATs)
for the treatment of RCRA-listed wastes.
These studies collected performance data
for industrial applications of recycling for a
wide range of metal-contaminated wastes,
including mercury-bearing wastes. The
EPA BOAT process considered recycling
as a treatment alternative for many
nonwastewater streams and identified re-
cycling as the BOAT for some
nonwastewater subcategories.
Recycling of mercury increased after
the development of Land Disposal Re-
strictions (LDRs) on mercury-containing
wastes. Like other metals, mercury can-
not be destroyed. Further, EPA review of
treatment data for the development of a
BOAT indicated that mercury is difficult to
reliably stabilize when present either at
high concentrations or in elemental form.
The analysis of treatability data did, how-
ever, indicate that low concentrations of
elemental mercury could be stabilized to
meet acceptable leachability levels for land
disposal. Applicable technologies for the
low-concentration mercury wastes were
stabilization, amalgamation, or acid leach-
ing followed by sulfide precipitation.
Because of lack of data on mercury
waste treatment by acid leaching followed
by solution processing, the EPA estab-
lished roasting and retorting as the BOAT
for all mercury nonwastewaters having to-
tal mercury concentrations above 260 mg/
kg, except for radioactive mixed wastes.
The affected RCRA wastes are D009 (mer-
cury characteristic), P065 (mercury fulmi-
nate), P092 (phenyl mercury acetate),
U151 (mercury), and K106 (wastewater
treatment sludge from the mercury cell
process in chlorine production). The EPA
also established incineration as a pretreat-
ment step for P065, P092, and D009 (or-
Table 1. Mercury Consumption in the United States by Use*
Use
Use in 1989
(MT)t
Use in 1992
(MT)
Chemical and allied products
Mercury cell chloralkali process
Laboratory uses
Paint
Other chemical related uses
Electrical and electronics
Electric lights
Devices and switches
Batteries
Instruments and related products
Measuring and control instruments
Dental
Other
Total
379
18
192
40
31
141
250
87
39
32
1,209
209
18
0
18
55
69
16
52
37
148
622
* Source: U.S. Bureau of Mines (1993).
f MT = metric ton (1 MT is equivalent to 1000 kg, 2,205 Ib, 1.102 short tons, and 29 flasks).
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ganics) before retorting in its June 1, 1990
rule (55 FR 22572 and 22626).
State Regulations
Several states have enacted or are con-
sidering legislation to prohibit mercury dis-
posal in municipal waste, discourage or
prohibit mercury use, or encourage mer-
cury recycling. The states with active or
planned mercury control regulations are:
• California
• Connecticut
• Florida
• Michigan
• Minnesota
• New Jersey
• New York
• Vermont
Source Reduction Alternatives
for Mercury in the Electrical and
Electronics Industries
The industry sectors covered by this
report are electrical and electronic device
manufacture (SIC 36) and measuring and
control instrument manufacture (SIC 382).
Source reduction alternatives to mercury
use continue to be developed and are
being used in the electrical lighting, bat-
tery, switching device, instrument, and ther-
mostat manufacturing areas. These
alternatives are discussed in the following
sections.
Electrical Lighting
In 1992, approximately 55 metric tons
of mercury were used in the electrical
lighting industry. Mercury-containing lamps
include fluorescent lamps and high-inten-
sity discharge (HID) lamps. Examples of
HID lamps include mercury vapor, metal
halide, and high-pressure sodium lamps.
Today, fluorescent lamps and HID fluo-
rescent lamps are the second largest
source of mercury in municipal solid waste
(household batteries are primary). By the
year 2000, mercury contamination result-
ing from the disposal of fluorescent lamps
to municipal solid waste is projected to
increase to 37.1 metric tons. Although
manufacturers are working to reduce the
mercury content of each lamp, increased
use of fluorescent lamps is expected be-
cause of their energy efficiency. The aver-
age life of an electrical fluorescent lamp is
4 yr, whereas that of a HID lamp is less
than 1 yr.
All fluorescent lamps contain mercury.
Mercury acts as a multiphoton source in
fluorescent lamps. The mercury content
typically ranges from 20 to 50 mg/tube,
depending on the size. Ultraviolet (UV)
light is produced by mercury when it is
bombarded by electrons produced by cur-
rent flowing through the tube. Phosphor
powders coated on the inside of the glass
tube convert the UV light to visible light.
The research to date shows that there
is no economically feasible alternative to
mercury in fluorescent lighting although
work is being done to find a way to re-
duce the amount of mercury used in elec-
trical lighting. Light bulbs produced today
contain 60% less mercury than those
manufactured 10 yr ago. Today a stan-
dard fluorescent lamp contains 0.05 mg/
m3 mercury, approximately 0.02% of the
total weight of the bulb.
Although the amount of mercury in
lamps is small, there is a growing market
for recycling the mercury, glass, and alu-
minum from fluorescent and mercury va-
por lamps. Fluorescent lamps can be
processed to recover several valuable re-
sources. The recovery process typically
involves crushing the tube and separating
the metal end pieces from the glass. Metal
components such as the end caps often
are sent to other recyclers for recovery.
The tube components are then roasted
and retorted to recover mercury. The glass,
phosphor, and mercury may be treated
together, or the glass may be separated
and only the phosphor treated. The result-
ing glass often is recycled. Mercury recov-
ered by retorting is purified by distillation
for reuse.
Batteries
In 1992, approximately 16 metric tons
of mercury were used in the United States
by the battery manufacturing industry. In
the past, mercury was added to alkaline-
manganese and zinc-carbon batteries to
control gassing, and U.S. manufacturers
were successful in reducing the mercury
content to below 250 ppm. In 1992, U.S.
manufacturers began producing mercury-
free alkaline-manganese batteries. Most
zinc-carbon batteries manufactured in the
United States no longer contain any mer-
cury.
Batteries represent the largest current
source of mercury in municipal solid waste.
In 1989, household batteries accounted
for 563.9 metric tons of the mercury dis-
carded in municipal solid waste. It is esti-
mated that by the year 2000, household
batteries will be responsible for only 89.4
metric tons of the mercury discarded in
municipal solid waste.
Beginning in 1992, several battery
manufacturers began selling mercury-free
alkaline batteries. Other metals such as
indium, gallium, and magnesium are sub-
stituted for mercury. In addition, the use
of mercuric oxide batteries, primarily for
hearing aids and pagers, is being replaced
by zinc-air batteries. Mercuric oxide bat-
teries will however, continue to be used
for medical and military applications be-
cause, currently, there are no acceptable
substitutes.
Switching Devices
Industrial and economic data suggest
that the quantity of mercury used in elec-
tronic control and switching devices is sig-
nificant. The characteristics of mercury
switching devices and some possible al-
ternatives that avoid mercury use are sum-
marized in Table 2.
Control Instruments
Mercury is used in many instrumenta-
tion devices such as thermometers and
mercury manometers. Mercury manom-
eters are considered reliable absolute-pres-
sure gages, and they provide the accuracy
needed for a system analysis. A common
application is in the steam jet air ejectors
used in process plants that have a supply
of available steam. Some mercury-free
units, such as electronic vacuum gages,
however, are accurate, portable pressure-
measuring instruments. Formerly, gas
regulators used mercury in a safety de-
vice (a U-shaped tube with mercury at the
base of the tube) that was designed to
divert gas flow outside of a building if the
gas line pressure became too high. If the
pressure were to exceed a safe value, a
weighed amount of mercury would be
ejected through an outside vent, subse-
quently relieving gas pressure. Modern
gas regulators use a mechanical spring
mechanism instead of mercury, although
older homes may still have gas regulators
that contain mercury.
Thermostats
Thermostats are temperature control
devices that usually consist of a tempera-
ture-sensing element, an electrical switch
that activates heating and cooling equip-
ment, and a mechanism for adjusting nomi-
nal temperature. Thermostats control
temperatures in large building spaces, in-
dividual rooms, and appliances, and some
types of thermostats use mercury in the
switch mechanism. Historically, mercury
switches have proven reliable, accurate,
long-lived, and cost efficient. These are
important qualities because thermostats
control the dispensation of large amounts
of electrical power, and their operational
efficiency has a large effect on fuel con-
sumption. Unoptimized thermostatic con-
trol can lead to many times more energy
consumption than necessary. Poor perfor-
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Table 2. Comparison Between the Mercury Switch and Its Alternatives.
Type
Properties
Application
Hazardous Content*
Mercury switch
Hard-contact switch
Solid-state switch
Electro-optical
switch
Inductive
sensor
Capacitive
sensor
Photoelectric
sensor
Ultrasonic sensor
Smooth contact, simple in design,
versatile, inexpensive
Metal-to-metal contact, may
be open or sealed, versatile,
inexpensive
More sophisticated design
features, versatile
Higher speed, expensive,
multiple user
Senses metal targets,
10 to 20 mm detection
Senses mass
Senses nontransparent, non-
reflective materials, up to
50 m away; high speed
Senses all objects,
range of about 0.5 m; high speed
On/off relay, thermostats,
circuit control
On/off relay, general circuit
controls, high or low voltage
Communications, circuit control,
electronic thermostats
Communications
Shaft rotation, conveyors
Conveyors
Conveyors
Conveyors
Mercury
None
Arsenic, gallium
Lithium, niobate
None
None
III- V semiconductor
materials
None
* Indicates hazardous materials other than lead, which may be used in solder.
mance may be caused by one of several
reasons, the main reason being hyster-
esis in the temperature-sensing compo-
nent, the electrical switch, or both.
Hysteresis may lead to large differentials,
or swings, in room temperature.
Analysis of thermostat markets indicates
that approximately 10 to 15 metric tons of
mercury are used annually in the United
States for the production of thermostats,
primarily for home heating and cooling
applications. Of the 70 million thermostats
in residential use today in the United
States, it is estimated that 90% use mer-
cury. Thermostat manufacturers estimate
that 2 to 3 million thermostats are brought
out of service each year. Most of these
thermostats are replaced by the
homeowner or contractor. The character-
istics of mercury tilt switch thermostats
and potential mercury-free alternatives are
summarized in Table 3.
Recycling Alternatives for
Mercury in the Electronics
Industry
There is a well-established infrastruc-
ture for recycling mercury-containing scrap
and waste materials. Industrial production
of mercury from recycling of secondary
sources amounted to 176 metric tons in
1992.
Many mercury compounds will convert
to metal at atmospheric pressure and
300°C or at lower temperature by direct
dissociation. With its boiling point of 357°C,
mercury also is substantially more volatile
than most metals. As a result, mercury
and mercury compounds can be sepa-
rated by roasting and retorting more eas-
ily than most metals, making it an ideal
candidate for recycling from a wide variety
of waste materials. A U.S. Bureau of Mines
study showed that thermal desorption pro-
cesses are potentially cost-effective for
recovery of mercury from a wide variety of
electrical manufacturing wastes. The full
report outlines the general characteristics
of several companies that recover mer-
cury from industrial wastestreams or spent
fluorescent lamps.
Conclusions
This study identified mercury sources
and consumption patterns and source re-
duction and recycling options for mercury
in the electronics industry. The alterna-
tives to mercury-containing electronic de-
vices are compared with mercury-
containing devices. The survey of alterna-
tives shows that many nonmercury op-
tions are available for the diverse
applications that make up the electronics
industry. Overall, it can be said that, al-
though mercury has had an important role
in manufacturing of high-quality electro-
mechanical products, it undoubtedly will
be replaced by more versatile and faster,
fully electronic equivalents in the future.
The shift from mercury-containing to
nonmercury-containing devices is gov-
erned as much by the natural evolution of
technology as by environmental aware-
ness. Devices based on newer technolo-
gies continually become more cost-
competitive than more conventional de-
vices that may contain mercury. For the
present, environmental awareness plays
a key role among industries that use mer-
cury in their products and processes. In
these industries, pollution prevention and
recycling are viable means for preventing
mercury escape to the environment.
Finally, recycling alternatives for mer-
cury in electronic products are given.
Vacuum retorting, a viable means of recy-
cling mercury, is becoming commercially
available. These recycling programs how-
ever, are unlikely to be available nation-
wide unless a means is found to streamline
the federal, state, and local approval pro-
cesses necessary for implementation.
The full report was submitted in fulfill-
ment of Contract No. 68-CO-0003 by
Battelle Memorial Institute under the spon-
sorship of the U.S. Environmental Protec-
tion Agency.
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Table 3. Comparison Between the Mercury Switch Thermostat and Its Alternatives
Switch Type Performance Applications Thermostat Price*
Mercury tilt switch
Mechanical snap-acting
switch
Open-contact magnetic
snap switch
Sealed-contact magnetic
snap switch
Electronic thermostat
Accurate, reliable, long
service life
Inexpensive, less reliable
Accurate, moderate
service life
Accurate, reliable,
long service life
Accurate, reliable,
un proven service life
Premium residential
heating/cooling
Electric strip heating,
ventilation?
Standard residential
heating/cooling
Premium residential
heating/cooling
Premium residential
heating/cooling
$40-80
$10-30
$30-50
$60-100
$70-1 4(f
t Primarily used on line-voltage equipment.
* Manufacturer's list price; includes thermostat unit, without clock or other options available in product line.
* Includes programmable features.
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B.M. Sass, M.A. Salem, and LA. Smith are with the Batelle Memorial Institute,
Columbus, OH 43201-2693.
Paul M. Randall is the EPA Project Officer (see below).
The complete report, entitled "Mercury Usage and Alternatives in the Electrical
and Electronics Industries," (Order No. PB94-165362AS; Cost: $19.50,
subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
Penalty for Private Use
$300
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EPA/600/SR-94/047
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