REPORT TO CONGRESS
Potential Export of Mercury
Compounds from the United States
for Conversion to Elemental
Mercury
October 14, 2009
United States Environmental Protection Agency
Office of Pollution Prevention and Toxic Substances
Washington, DC 20460
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October 14,2009 U.S. Environmental Protection Agency
Table of Contents
Acronyms and abbreviations viii
Executive Summary ix
Introduction: Background and Purpose ix
Selection of Mercury Compounds for Assessment in this Report x
Mercury Compound Sources, Amounts, Purposes, and International Trade xi
Potential for Export of Mercury Compounds to be Used as a Source for Elemental Mercury xi
Other Relevant Information xii
Conclusions of Assessment of Potential for Export of Mercury Compounds xvi
1. Introduction 1
1.1 Background 1
1.1.1 Concern about Mercury in the Environment 1
1.1.2 Elemental Mercury: Chemistry, Uses, and DOD and DOE Surpluses 1
1.1.3 Summary of U.S. Mercury Export Ban 2
1.1.4 Summary of EU Export Ban on Mercury and Mercury Compounds 3
1.1.5 Relationship Among Mercury Compounds, International Mercury Demand, and the
U.S. Mercury Export Ban 3
1.1.6 Statutory Requirements of the Report to Congress on Mercury Compounds 4
1.2 Purpose of the Report 5
1.3 Report Organization 5
2. Selection of Mercury Compounds and Discussion of Data Availability 6
2.1 Method of Selecting Mercury Compounds Included in This Report 6
2.1.1 Note on Dental Amalgam 7
2.1.2 Criteria for Inclusion 7
2.2 Data Sources and Limitations 8
2.2.1 Substance Registry Services Database 8
2.2.2 Inventory Update Reporting Database 8
2.2.3 Toxics Release Inventory 9
2.2.4 Biennial Reporting System 9
2.2.5 NEWMOA, IMERC, and the EPA Mercury-Containing Products and Alternatives
Database 9
2.2.6 Data on U.S. Imports and Exports of Mercury Compounds 10
2.2.7 1997 Report to Congress 11
3. Sources, Uses, and International Trade in Mercury Compounds 12
3.1 Sources and Amounts of Mercury Compounds Imported or Manufactured 12
3.1.1 Mercury Compounds Imported Into the United States 12
3.1.2 Commercial Products Manufactured Domestically and Abroad 14
3.1.3 Byproducts 17
3.1.3.1 Gold Mining and Mercury Compound Generation (Mercury(I) Chloride) 18
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3.1.3.2 Sulfide Ore Roasting and Mercury Compound Generation (Mercury(I)
Chloride, Mercury(II) Sulfate, Mercury(II) Sulfide, and Mercury(II) Selenide) 22
3.1.4 Mercury Compounds in Waste 22
3.1.4.1 Mercury Compound Wastes from the Chlor-Alkali Manufacturing
Process 24
3.1.4.2 Remediation of Mercury from Contaminated Sites and Effluents 25
3.1.4.3 Special Case: Mercury Sulfide Waste 26
3.1.5 Stockpiles of Mercury Compounds among End-Use Consumers 27
3.1.6 Naturally Occurring Mercury Compounds 27
3.1.7 Summary Sources of Mercury Compounds 27
3.2 Purposes and Amounts of Mercury Compounds used: Current and Future 29
3.2.1 Current Uses 29
3.2.2 Estimated Amounts of Mercury Compounds To Be Used for Each Purpose in 2010
and Beyond 30
3.3 Sources and Amounts of Mercury Compounds Exported 30
4. Potential for Export of Mercury Compounds To Be Used as a Source for Elemental
Mercury 33
4.1 Chemistry and Technological Feasibility of Conversion 33
4.1.1 Conversion of Elemental Mercury to Mercury Compounds 33
4.1.1.1 The Thermal Oxidation of Elemental Mercury into Mercury(II) Oxide 34
4.1.1.2 The Chemical Conversion of Elemental Mercury into Mercury Halides ....34
4.1.1.3 The Chemical Conversion of Elemental Mercury in Waste Streams into
Mercury Halides 34
4.1.2 Conversion of Mercury Compounds to Other Mercury Compounds 34
4.1.3 Conversion of Mercury Compounds to Elemental Mercury 35
4.1.3.1 Thermal Decomposition 35
4.1.3.2 Chemical Reduction 35
4.1.3.3 Electrochemical Reduction 35
4.1.4 Organomercury Compounds 36
4.1.5 Candidate Compounds for Sources of Elemental Mercury Based on Technological
Feasibility of Conversion 36
4.2 Economic Feasibility of Exporting Mercury Compounds to Regenerate Elemental Mercury38
4.2.1 Overview of Options for Mercury Compound Export 39
4.2.2 Key Market Dynamics and Features Affecting Compound Manufacture 41
4.2.3 General Economic Considerations: Current Prices of Elemental Mercury and
Compounds 42
4.2.4 U.S. Production Capacity for High-Volume, Low-Cost Compound Production 44
4.2.5 Supply and Demand Information for Elemental Mercury 45
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4.2.5.1 Global Elemental Mercury Market 45
4.2.5.2 U.S. Elemental Mercury Market 48
4.2.5.3 Implications of Global Mercury Market for Compound Trade 49
4.2.6 Consideration of Specific Compounds with Potential to Supply Elemental Mercury49
4.2.7 Capacity Outside of the United States To Convert Compounds to Elemental
Mercury 50
4.3 Assessment of Potential for Export of Compounds Based on Technological and Economic
Factors 51
4.4 Summary of Technical and Economic Feasibility of Potential for Export 59
5. Other Relevant Information To Assist Congress in Determining Whether To Extend the
Export Ban 62
5.1 European Union Ban on Export of Mercury and Mercury Compounds 62
5.2 Evidence That Mercury Compounds Are Exported for Processing into Elemental Mercury63
6. Report Conclusions 64
References 66
Appendix A - Mercury Compound Identifying Information 74
Appendix B - Mercury Compounds in the IUR Database 75
Appendix C - Individual Mercury Compound Summaries 76
C.I Mercury(II) acetate 76
C.I.I Product description 76
C.1.2 Product uses 76
C.1.3 Synthesis from mercury 76
C.1.4 Reduction to elemental mercury 76
C.1.5 Potential sources 77
C.I.6 Potential for export as an alternative to mercury 77
C.2 Mercury(I) chloride 78
C.2.1 Product description 78
C.2.2 Product uses 78
C.2.3 Synthesis from mercury 78
C.2.4 Reduction to elemental mercury 79
C.2.5 Potential sources 79
C.2.6 Potential for Export as an Alternative to Mercury 80
C.3 Mercury(II) chloride 81
C.3.1 Product description 81
C.3.2 Product uses 81
C.3.3 Synthesis from mercury 82
C.3.4 Reduction to elemental mercury 82
C.3.5 Potential sources 82
C.3.6 Potential for export as an alternative to mercury 82
C.4 Mercury(II) iodide 84
C.4.1 Product Description 84
C.4.2 Product Uses 84
C.4.3 Synthesis from mercury 84
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C.4.4 Reduction to elemental mercury 85
C.4.5 Potential sources 85
C.4.6 Potential for export as an alternative to mercury 85
C.5 Mercury(II) nitrate 86
C.5.1 Product description 86
C.5.2 Product uses 86
C.5.3 Synthesis from Mercury 86
C.5.4 Reduction to elemental mercury 86
C.5.5 Potential sources 87
C.5.6 Potential for export as an alternative to mercury 87
C.6 Mercury(II) oxide 88
C.6.1 Product description 88
C.6.2 Product uses 88
C.6.3 Synthesis from mercury 88
C.6.4 Reduction to elemental mercury 89
C.6.5 Potential sources 89
C.6.6 Potential for export as an alternative to mercury 89
C.7 Mercury(II) selenide 91
C.7.1 Product description 91
C.7.2 Product uses 91
C.7.3 Synthesis from mercury 91
C.7.4 Reduction to elemental mercury 91
C.7.5 Potential sources 91
C.7.6 Potential for export as an alternative to mercury 91
C.8 Mercury(II) sulfate 93
C.8.1 Product description 93
C.8.2 Product uses 93
C.8.3 Synthesis from mercury 93
C.8.4 Reduction to elemental mercury 93
C.8.5 Potential sources 93
C.8.6 Potential for export as an alternative to mercury 94
C.9 Mercury(II) sulfide 95
C.9.1 Product description 95
C.9.2 Product uses 95
C.9.3 Synthesis from mercury 95
C.9.4 Reduction to elemental mercury 95
C.9.5 Potential sources 96
C.9.6 Potential for export as an alternative to mercury 96
C.10 Mercury(II) thiocyanate 97
C.10.1 Product description 97
C.10.2 Product uses 97
C.10.3 Synthesis from mercury 97
C.10.4 Reduction to elemental mercury 97
C.10.5 Potential sources 97
C.10.6 Potential for export as an alternative to mercury 98
C.ll Phenyl mercury(II) acetate 99
C.ll.l Product description 99
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C.11.2 Product uses 99
C.11.3 Synthesis from mercury 99
C.11.4 Reduction to elemental mercury 99
C.11.5 Potential sources 100
C.11.6 Potential for export as an alternative to mercury 100
C.12 Thimerosal 101
C.12.1 Product description 101
C.12.2 Product uses 101
C.12.3 Synthesis from mercury 102
C.12.4 Reduction to elemental mercury 102
C.12.5 Potential sources 102
C.12.6 Potential for export as an alternative to mercury 102
Appendix D - Detailed Chemistry of Mercury Compounds 103
D.I Conversion of elemental mercury to mercury compounds 103
D.I.I The chemical transformation of elemental mercury into mercury(II)
sulfide 103
D.I.2 The chemical transformation of mining byproducts into mercury(II)
sulfide 103
D.I.3 The chemical reaction of elemental mercury with acids to form
mercury nitrates and sulfates 103
D.1.4 The chemical oxidation of elemental mercury in acetic acid to form
mercury(II) acetate 104
D.2 Reactivity of mercury compounds 104
D.3 Conversion of Mercury Compounds to Elemental Mercury 104
D.3.1 Thermal Decomposition 104
D.3.2 Electrochemical reduction 105
D.4 Organomercury compounds 105
D.4.1 Phenylmercury(II) carboxylates 106
D.4.2 Thimerosal 106
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List of Tables
Table ES-1: Summary of Information on Mercury Compounds Required in the Mercury
Export Ban Act of 2008 xiv
Table 2-1: Mercury Compounds by Criteria for Inclusion in the Report 8
Table 2-2: HTS Headings Dealing with Mercury and Its Compounds, Preparations, and
Products 11
Table 3-1: Quantity and Value of U.S. Imports of Inorganic and Organic Mercury
Compounds, by Trade Database Source, 2007-2008 13
Table 3-2: Quantities of Mercury Compounds Sold in the United States (kilograms) 15
Table 3-3: Firms Reporting Manufacture of Mercury Compounds in the United States, 2004 16
Table 3-4: Mercury Compounds Manufactured in the United States in 2001, 2004 17
Table 3-5: Total Mercury Byproduct Recovered for Sale (metric tons elemental mercury) 19
Table 3-6: Mercury Recovered at the Barrick Goldstrike Mine (metric tons elemental
mercury) 19
Table 3-7: Nevada Gold Mine Mercury Byproduct Sales to Recycling Companies 19
Table 3-8: Annual Mercury and Mercury Compound Byproduct Reported under the
Nevada Mercury Control Program (metric tons) 20
Table 3-9: TRI Report of Mercury Compound Waste Quantities Reported by Gold Ore
Mining Industry for 2007(kilograms mercury) 22
Table 3-10: TRI Release and Waste Management Data for Mercury Compounds for the
Alkalies and Chlorine Manufacturing Industry (kilograms) 25
Table 3-11: Domestic Sources of Mercury Compounds in the United States (kilograms) 28
Table 3-12: Purposes for Which Mercury Compounds Are Used and Amounts Consumed
by Use 29
Table 3-13: Quantity and Value of U.S. Exports of Inorganic and Organic Mercury
Compounds, by Trade Database Source, 2007-2008 31
Table 4-1: Candidate Compounds, Sources, Feasibility of Conversion, and Potential for
Export Based on Technological Feasibility 37
Table 4-2: Market Prices of Elemental Mercury and Selected Mercury Compounds 44
Table 4-3: Summary of Technological Feasibility, Economic Feasibility, and Overall
Potential for Export of Candidate Compounds 53
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List of Figures
Figure 4-1: Mercury Compound Products 39
Figure 4-2: Mercury Compounds in Waste or as Byproduct 40
Figure 4-3: Conversion of Elemental Mercury for Export as Mercury Compounds 40
Figure 4-4: Historical Prices for Elemental Mercury: 1929 - 2009 43
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U.S. Environmental Protection Agency
Acronyms and abbreviations
BDAT Best Demonstrated Available Technology
BRS Biennial Reporting System
COD Chemical Oxygen Demand
DOD United States Department of Defense
DOE United States Department of Energy
EPA United States Environmental Protection Agency
EPCRA Emergency Planning and Community Right-to-Know Act
EU European Union
HTS Harmonized Tariff Schedule
IMERC Interstate Mercury Education and Reduction Clearinghouse
U.S. ITC United States International Trade Commission
IUR Inventory Update Reporting
MEBA Mercury Export Ban Act of 2008
kg kilogram
mg/kg milligrams per kilogram (= parts per million)
mg/1 milligrams per liter
mt metric tons
NDEP Nevada Division of Environmental Protection
NEWMOA Northeast Waste Management Officials' Association
NMCP Nevada Mercury Control Program
NvMACT Nevada maximum achievable control technology
OPTC Operating Permit to Construct
ppm parts per million
RCRA Resource Conservation and Recovery Act of 1976
SRS Substance Registry Services
TRI Toxics Release Inventory
TSCA Toxic Substances Control Act
VMRP Voluntary Mercury Reduction Program
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Executive Summary
Introduction: Background and Purpose
Mercury is a naturally occurring element that is mobilized in the environment from natural
sources (such as volcanoes) and human activities (such as industrial combustion and mining).
Mercury is well-documented as a toxic chemical that is atmospherically transported on a local,
regional, and global scale by cycling among air, land, and water. Because it is an element,
mercury does not degrade.
Elemental mercury can be transformed in the environment into methyl mercury, which can be
highly toxic depending on exposure and which biomagnifies in fish, including species
consumed by humans. A number of adverse health effects associated with exposure to methyl
mercury have been identified in humans and in animal studies. Most extensive are the data on
neurotoxicity, particularly in developing organisms. The nervous system is considered to be the
most sensitive target organ.
EPA is working on both domestic and international fronts to reduce mercury in the
environment and to prevent human exposure to it. The Agency has issued regulations to
reduce mercury releases to air, water, and land; and works with a variety of stakeholders,
including the waste management and health care industries, to encourage voluntary efforts to
reduce or eliminate mercury pollution.
The Mercury Export Ban Act of 2008 (MEBA), signed on October 14, 2008, prohibits the export
of elemental mercury from the United States beginning in 2013. MEBA does not ban the export
of mercury compounds. The prohibition on export of elemental mercury is intended to reduce
the availability of elemental mercury on the global market. MEBA contains several other
provisions and requires federal agencies to submit reports and other information to Congress.
This report is submitted to fulfill Section 4 of MEBA, which states:
"REPORT TO CONGRESS ON MERCURY COMPOUNDS -
(A) REPORT- Not later than one year after the date of enactment of the Mercury
Export Ban Act of 2008, the Administrator shall publish and submit to Congress a
report on mercuric chloride, mercurous chloride or calomel, mercuric oxide, and
other mercury compounds, if any, that may currently be used in significant
quantities in products or processes. Such report shall include an analysis of
(i) the sources and amounts of each of the mercury compounds imported into the
United States or manufactured in the United States annually;
(ii) the purposes for which each of these compounds are used domestically, the
amount of these compounds currently consumed annually for each purpose, and
the estimated amounts to be consumed for each purpose in 2010 and beyond;
(iii) the sources and amounts of each mercury compound exported from the
United States annually in each of the last three years;
Report to Congress ix
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(iv) the potential for these compounds to be processed into elemental mercury
after export from the United States; and
(v) other relevant information that Congress should consider in determining
whether to extend the export prohibition to include one or more of these mercury
compounds.."
Selection of Mercury Compounds for Assessment in this Report
EPA began with a list of approximately 200 mercury compounds and identified 12 which are
currently produced and have some technological feasibility to be exported for elemental
mercury generation. The group of twelve compounds includes the three identified by MEBA to
be in this report. All but one of the selected compounds are manufactured (or imported) in very
small quantities and used as specialty chemicals. In 2004, which is the most recent year that
data are available, total sales of these chemicals were less than one metric ton.
Several of the selected mercury compounds also occur in industrial waste or byproducts. The
only available quantity estimate is for byproduct mercury(I) chloride. Approximately 25 metric
tons of elemental mercury is obtained annually from processing byproduct mercury(I) chloride.
Mercury(I) chloride is one of the three compounds identified in MEBA, where it is referred to as
"mercurous chloride or calomel."
Although there is a significant quantity of only one compound, mercury (I)chloride, EPA
assessed all 12 for their potential to be produced in larger quantities for export. An incentive for
such production might result from the surplus of elemental mercury caused by the MEBA ban
on exports of elemental mercury beginning January 1, 2013. The excess mercury will need to be
placed in permitted, long-term storage if it is not used. Costs of storage could be avoided for
elemental mercury that is converted into mercury compounds for export and subsequent
reconversion to elemental mercury in other countries. This scenario is the reason EPA assessed
mercury compounds that are currently marketed in the United States in very small quantities.
Some of the 12 mercury compounds manufactured as specialty chemicals, and identified for
closer assessment in this report, also occur as industrial byproducts or waste. The assessment
took into account these additional volumes because after the export ban takes effect, it may be
more economical to export byproducts and waste for conversion to elemental mercury outside
the United States than to continue the current practice of retorting them in the United States and
having to store the resulting elemental mercury. EPA did not find any mercury compounds
contained in byproducts or waste that are not also in the group of 12 already identified.
EPA did not include in its assessment wastes with de minims1 amounts of mercury compounds.
Also excluded from this report are any mercury compounds in coal or resulting from coal
combustion or found in manufactured consumer products. EPA did not assess these sources
because of language in the legislative history of MEBA: "the Committee does not intend that
this prohibition [ban on export of elemental mercury] prevent exportation of coal or fly ash, a
1 The term de minimis is used in this report to mean "insignificantly small."
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Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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by-product of coal combustion, or manufactured consumer products containing elemental
mercury."2 EPA reasoned that if Congress did not prohibit export of mercury occurring in
manufactured consumer products or materials from coal combustion, then it was not important
to assess the export of compounds in those items at this time.
Data Limitations
Information is not available at the level of specificity for all report topics required by MEBA.
The act directs EPA to report on the sources and annual amounts of each mercury compound
manufactured, imported, and exported; the uses of each compound; the annual amounts of each
use; and estimates of each future use. There is limited public data on amounts of mercury
compounds sold as specialty chemicals and on the uses of those chemicals that is collected by 14
states. The information is available for the years 2001 and 2004. There is not enough time-series
sales data to provide a basis for accurately estimating future use.
More significant quantities of mercury compounds are produced in byproducts and waste, but
quantity information is not collected. Import and export quantities and countries are reported
only for mercury compounds as a group, and these aggregate amounts are not consistent
enough to be useful.
Mercury Compound Sources, Amounts, Purposes, and International Trade
Mercury(I) chloride is the highest volume mercury compound generated in the United States.
While it is manufactured in small amounts for specialty uses such as chemical and
pharmaceutical applications, the large quantities generated and traded in the United States
(roughly 25 metric tons of elemental mercury) are contained in byproducts from pollution
control activities at gold mines. Elemental mercury is processed from byproduct mercury(I)
chloride. An unknown quantity of mercury(I) chloride is imported into the United States, also
for conversion to elemental mercury.
Four other mercury compounds (mercury(II) oxide, mercury (II) selenide, mercury(II) sulfide,
and mercury(II) sulfate) can occur as byproducts or in waste; quantities are not known. All
twelve mercury compounds are made as specialty chemicals that are sold for pharmaceutical
and laboratory uses in quantities ranging from 0.2 kilograms to 261 kilograms. The quantities
of imports and exports of these compounds are not known.
EPA was unable to find any evidence that compounds are currently exported from the United
States for processing into elemental mercury in other countries.
Potential for Export of Mercury Compounds to be Used as a Source for Elemental
Mercury
For each selected individual mercury compound, EPA evaluated both the technological
feasibility and the economic feasibility of creating, shipping, and processing the compound into
elemental mercury.
2 S. Rep. No. 110-477. 2008. Senate Report 110-477 - Mercury Market Minimization Act of 2007. Available online at:
http://frwebgate.access.gpo. go v/cgi-bin/getdoc.cgi?dbname=110_cong_reports&docid=f: sr477.110.pdf
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Technological Feasibility
Mercury compounds that could be exported for the purpose of regenerating elemental mercury
must be readily available (or easily generated), chemically stable, transportable, and easily
converted to elemental mercury. Chemical processes ideally suited to this end will use
inexpensive, readily available reagents, and simple procedures and equipment.
Economic Feasibility
In addition to being technologically feasible, it must be economically feasible to export
compounds as a substitute supply for elemental mercury. For manufactured mercury
compounds, economic feasibility requires that the costs of creating and exporting mercury
compounds, combined with the cost of regenerating the elemental mercury in other countries,
will be lower than the cost of producing elemental mercury from sources outside of the United
States. If the mercury compound is produced as a byproduct or as part of a waste stream, then
there is no "production" cost. After the export ban, there will be a cost to store the surplus
elemental mercury that is produced from byproducts and waste. It will be economically
feasible to export byproducts and waste containing mercury compounds for conversion to
elemental mercury abroad only if the avoided costs of storage (or other disposition of the
mercury in the United States), added to the revenue from selling elemental mercury abroad, are
greater than the costs of shipment and overseas processing.
EPA qualitatively characterized the costs, cost savings, and revenue expected to result if
mercury compounds are exported for conversion to elemental mercury. These findings were
considered in light of certain characteristics of the global market for elemental mercury. For
example, if a firm considered scaling up production of a mercury compound because of the
abundance of elemental mercury in the United States after the ban, it would need to take into
account the fact that world mercury prices are likely to remain stable in the long-run ,world
demand is uncertain (due to declining use in many countries and rising use in artisanal gold
mining), and large secondary sources of mercury may be available from tailings from mining,
smelting, and natural gas, and from stockpiles in various countries.
Other Relevant Information
An understanding of the European Union's export ban is relevant to consideration by the U.S.
Congress of expanding the U.S. ban to include mercury compounds. On October 22, 2008, the
European Union expanded its future ban on the export of metallic (i.e., elemental) mercury to
include:
cinnabar ore3
mercury(I) chloride
mercury(II) oxide, and
3 Cinnabar ore is mercury(II) sulfide and is abundant in the European Union.
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mixtures of metallic mercury with other substances, including alloys of mercury, with a
mercury concentration of at least 95 percent by weight.
The amended EU export ban provides exceptions for research and development, medical, or
analysis purposes. Also, the EU regulation prohibits mixing metallic mercury with a substance
for the sole purpose of export of metallic mercury. The effective date of the ban on exports
(including metallic mercury) is March 15, 2011.
Summary of Information Required for this Report
This table presents in brief form EPA's research and analysis on each topic required in Section 4
of MEBA. Findings in the last column (potential for export) are developed more fully in the
Conclusions section immediately following the table.
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U.S. Environmental Protection Agency
Table ES-1: Summary of Information on Mercury Compounds Required in the Mercury Export Ban Act of 2008
Compound
Name
Mercury (I)
chloride
Mercury (II)
nitrate
Mercury (II)
oxide
Mercury (II)
sulfate
Mercury (II)
sulfide
Mercury (II)
acetate
Produced in U.S.
Source Sector
Air pollution
byproduct at
mines
Chemical
manufacturing
Chemical
manufacturing
Chemical
manufacturing;
Battery
recycling
Chemical
manufacturing;
Waste
treatment
Naturally
occurring;
Chemical
manufacturing;
Waste
treatment
Chemical
manufacturing
Quantity
in 2004
(kg)
~25,OOOHg
1.3
88.7
32.5
260.8
(amount
from
waste
treatment
unknown)
0.6
(amount
from
waste
treatment
unknown)
41.3
Imported
Source
Data for individual compounds not currently available
Quantity
(annual)
0)
1
ca
0)
SH
3
"o
^
Td
3
0
u
la
Td
Td
IH
"8
O
Purposes and Uses
1. Processed for elemental
mercury regeneration
2. Calomel (mercury(I)
chloride) electrodes
1. Preparation of other
mercuric products
2. Analytic reagent (test kits)
1. Batteries
2. Synthesis of other
mercury compounds
3. Analytical reagent
1. Gold and silver extraction
2. Reagent
1. Extraction of elemental
mercury
2. Pigment
1. Manufacture of
organomercuric compounds
2. Catalyst or reagent
Quantity
used
annually
in U.S.
0)
JH
1
ca
0)
SH
U
"o
&
c
0
la
Td
IH
ca
"8
O
Quantity
used 2010
& after
0)
1
'3
ca
0)
u
"o
ca
.0
1
cT
DH
ca
,0
o
ฃ
o
3
ta
O
Sources and
quantities
exported in last
three years (2006,
2007, 2008)
Data for individual compounds not currently available
Potential for
export for
regeneration
of elemental
mercury
Likely
Unlikely
somewhat
likely
somewhat
likely
somewhat
likely
somewhat -
Unlikely
Unlikely
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U.S. Environmental Protection Agency
Table ES-1: Summary of Information on Mercury Compounds Required in the Mercury Export Ban Act of 2008
Compound
Name
Mercury (II)
chloride
Mercury (II)
iodide
Phenyl
mercury (II)
acetate
Mercury (II)
selenide
Mercury (II)
thiocyanate
Thimerosal
Produced in U.S.
Source Sector
Chemical
manufacturing
Chemical
manufacturing
Chemical
manufacturing
Mining waste;
Waste
treatment
Chemical
manufacturing
Chemical
manufacturing
Quantity
in 2004
(kg)
76.8
11.3
0.2
Unknown.
6.4
Unknown
Imported
Source
Data for individual compounds not currently available
Quantity
(annual)
Data for individual compounds not currently available
Purposes and Uses
1. Catalyst or reagent
2. Mercury capture waste
procedures
1. Mayer's or Nessler's
reagent
2. Nuclear particle detection
instruments
1. Preservative
2. Preparation of other
phenylmercury compounds
1. Mining waste
2. Mercury capture waste
procedures
3. Semiconductor
1. Analytical reagent
2. Photography (intensifier)
1. Preservative
Quantity
used
annually
in U.S.
Data for individual compounds not currently available
Quantity
used 2010
& after
Data for individual compounds not currently available
Sources and
quantities
exported in last
three years (2006,
2007, 2008)
Data for individual compounds not currently available
Potential for
export for
regeneration
of elemental
mercury
Unlikely
Unlikely
Unlikely
Very
Unlikely
Very
Unlikely
Very
Unlikely
* Estimate based on discussions with Melissa Barbanell, Barrick Gold Corporation (personal communication June 18, 2009) and refers to mercury content only.
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Conclusions of Assessment of Potential for Export of Mercury Compounds
> One mercury compound, mercury(I) chloride, is likely to be exported and
processed into elemental mercury after export. This compound is currently
produced in significant quantities as a byproduct of U.S. gold mining, then
converted to elemental mercury. After the export ban, producers will have
incentives to avoid the cost of retort (conversion to elemental mercury using
heat) and long-term storage of the elemental mercury. Mercury(I) chloride is
easily reduced to elemental mercury and the yield is high (85% by weight). It is
not clear, however, that global recovery of elemental mercury from mercury(I)
chloride would spread beyond a handful of sophisticated processors, because the
technology for recovery is highly specialized.
> Three other mercury compounds could possibly be exported and processed into
elemental mercury after export. Mercury(II) oxide, mercury(II) sulfate, and
mercury(II) nitrate are readily available as a byproduct or produced easily from
surplus elemental mercury. They are easily reduced to elemental mercury and
the yield is high (ranging from 62% to 93%). These compounds are produced in
the United States, so some capacity exists, although quantities are small.
However, significant capital investment would be required to produce larger
quantities in the United States, and it is not clear that anticipated elemental
mercury prices are high enough to justify the investment at this time.
Mercury(II) sulfate is also currently generated as waste, which could possibly be
purified for sale or exported.
Production of mercury(II) nitrate and mercury(II) sulfate involves the handling
of toxic substances such as sulfuric acid and generates mercury-containing
wastes, which can increase expenses. Mercury(II) oxide is an interim product of
several recovery processes and is relatively simple to manufacture, though it
generally is produced from other compounds, including mercury(II) sulfate and
mercury(I) chloride, and is more inefficient to produce from elemental mercury.
If mercury(I) chloride export is banned, it is possible that production of
mercury(II) oxide could become more cost-competitive. Because mercury(II)
oxide is currently produced as an interim product in processing mercury(I)
chloride, an increase in domestic mercury(I) chloride supplies would likely
reduce the cost of producing mercury(II) oxide.
> It is not likely that the other eight mercury compounds assessed in this report
will be exported and processed into elemental mercury. These compounds are
currently produced only in small quantities for specialized laboratory or
industrial uses. These eight compounds either cannot be converted to elemental
mercury by heating or require manufacturing from other chemicals and thus
require an extra production step. Producing, exporting, and converting these
compounds into elemental mercury is likely to be too costly compared with costs
of supplying mercury to the global market from other sources.
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1. Introduction
1.1 Background
1.1.1 Concern about Mercury in the Environment
Mercury is a naturally occurring element. Mercury is mobilized from natural sources (such as
volcanoes) and human activities (such as industrial combustion and mining) and mercury
contamination is widespread in the United States and global environment. Human activities
have increased the amount of mercury that is mobilized in the atmosphere; in soils and
sediments; and in lakes, streams, and oceans (U.S. EPA, 2006, EPA's Roadmap for Mercury).
Mercury can then be transported, depending on the form emitted and other factors, on local,
regional and global scales before depositing in water. In aquatic ecosystems, mercury can be
environmentally transformed into the organic form of mercury, methyl mercury, which can
bioaccumulate and biomagnify through food webs, and is highly toxic.
Mercury exposure can cause a number of adverse effects on human health. These effects vary
depending on the form of mercury to which a person is exposed and the level and length of
exposure. The primary way humans are exposed to mercury is through eating fish containing
methyl mercury. Methyl mercury exposure can cause neurological impairment, though
research shows that most people's fish consumption does not cause a health concern (U.S. EPA,
2006). Fetuses and very young children are more sensitive to methyl mercury than adults.
Methyl mercury in the mother's body passes to the fetus and may accumulate there. There is
evidence in adults that methyl mercury also affects other systems. Specifically, some studies
suggest that prolonged exposure to methyl mercury, especially at higher levels, can harm the
heart, kidneys, and immune system. However, additional studies are needed to better
categorize the effect of methyl mercury on these health endpoints (U.S. EPA, 2006). In addition
to methyl mercury, individuals may also become exposed to harmful levels of elemental
mercury found indoors in work places and in homes. When exposed to air, elemental mercury
volatilizes and can be inhaled (U.S. EPA, 2006).
EPA is working to reduce mercury in the environment and to prevent exposure to humans.
EPA and the Food and Drug Administration issued joint fish consumption advisories in 2004
and updated the national listing of fish advisories in 2007 which is an advisories database that
includes advisories issued by state authorities. On an ongoing basis, EPA issues regulations to
reduce mercury releases to air, water, and land, and works with many others, including several
industries, such as waste management and health care, to encourage voluntary efforts to reduce
or eliminate mercury pollution. In addition, EPA works with other countries to reduce mercury
pollution (U.S. EPA 2009a). One EPA initiative concerned the problem of surplus quantities of
commodity-grade mercury in the United States. In 2007, EPA brought together stakeholders to
receive information and suggestions on options for managing this privately-held mercury.
1.1.2 Elemental Mercury: Chemistry, Uses, and DOD and DOE Surpluses
Elemental mercury (Hgฐ) is unique among metals because it is a liquid at room temperature, it
has a low boiling point, and it has high vapor pressure. Elemental mercury's high vapor
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pressure facilitates its removal from mixtures by volatilization, and thermal decomposition of
mercury compounds at elevated temperatures often generates elemental mercury vapor, which
can be condensed and collected (i.e., "retorted"). Elemental mercury can also react to form
compounds in either the (Hg1+) or (Hg2+) oxidation state. Many of these mercury compounds,
such as the halide salts, oxides, and nitrates, can be readily interconverted or transformed back
into elemental mercury. In addition, mercury forms stable, covalent bonds with carbon or can
form metallic bonds in metal alloy mixtures commonly called amalgams (Patnaik, 2003).
Because of these properties, humans have used mercury for a variety of purposes beginning
thousands of years ago. In modern times, mercury has been used as a processing agent in the
mining of gold, as a cathode in the manufacture of chlorine and caustic soda, and as a
component in several types of industrial and consumer products, including measurement,
switch, and lighting applications.
The U.S. Department of Defense and the U.S. Department of Energy (DOE) formerly stockpiled
elemental mercury for use in a range of applications. Prior to 2008, both agencies voluntarily
committed to storing, rather than selling, their mercury stockpiles. The Mercury Export Ban
Act of 2008 (MEBA) specifically prohibits federal agencies from selling, distributing, or
transferring elemental mercury except to facilitate storage.
In private markets in the United States, the European Union, and other industrialized countries,
use of mercury has declined as substitutes have become available. Mining of mercury ore in the
United States essentially stopped in the mid-1990s, though production of elemental mercury as
a byproduct at gold mines continues where ores of gold also have substantial quantities of
naturally-occurring mercury. At the same time, elemental mercury is also regenerated from
industrial processes and made available for reuse. Concern exists that this regenerated
elemental mercury can be used in ways that result in human exposure and environmental
release. Of particular concern is the increasing use of elemental mercury (in developing
countries) as a processing agent to extract gold from rock and soil by poor, small-scale gold
miners, including women and children. These artisanal miners are often exposed to mercury
through inhalation, and elemental mercury that is not recaptured for reuse is released to air,
water, and land during this use.
1.1.3 Summary of U.S. Mercury Export Ban
The MEBA, enacted on October 14, 2008, includes the following provisions:
> The export of elemental mercury from the United States is prohibited, effective January
1, 2013
> Effective immediately upon enactment, Federal agencies are prohibited from conveying,
selling or distributing elemental mercury under Federal control or jurisdiction to any
other Federal agency, any State or local government agency, or any private individual
or entity except for transfers to facilitate storage or transfers of coal
> The Federal government must provide long-term management and storage of any
elemental mercury generated within the United States
> EPA and DOE are responsible for submitting the following to Congress:
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A report on mercury compounds (to be submitted by EPA no later than October 14,
2009);
Annual reports on the previous year's incurred costs associated with the long-term
storage and management of elemental mercury (to be submitted by DOE no later
than 60 days after the end of each fiscal year);
A study on the impact of the long-term storage program on mercury recycling (to be
submitted by DOE no later than July I, 2014); and
A report on global supply and trade of elemental mercury (to be submitted by EPA
at least three years after the effective date of the export prohibition but no later than
January I, 2017).
> DOE is to make available guidance related to the procedures and standards for receipt
management and long-term storage of elemental mercury (no later than October I, 2009
by DOE)
MEBA bans the export of elemental mercury from the United States, but does not ban the export
of mercury compounds.
1.1.4 Summary of EU Export Ban on Mercury and Mercury Compounds
In 2007, the European Union passed a regulation banning the export of elemental mercury. On
October 22, 2008, the European Union expanded the mercury export ban to include certain
mercury compounds and mixtures. This ban applies to exports after March 15, 2011. The
expanded ban prohibits the export of metallic mercury (elemental mercury), mercury(I)
chloride; mercury(II) oxide; cinnabar ore; and mixtures of metallic mercury with other
substances, including alloys of mercury, with a mercury concentration of at least 95 percent by
weight.4 There are exceptions to the ban for elemental mercury or mercury compounds used for
research and development, medical, or analysis purposes. For further information on the EU
ban, see Section 5.1, European Union Ban on Export of Mercury and Mercury Compounds.
1.1.5 Relationship Among Mercury Compounds, International Mercury Demand, and the
U.S. Mercury Export Ban
Elemental mercury is currently a commodity that is bought and sold worldwide. The U.S.
export ban will not change the fact that excess mercury will continue to be produced in the
United States and that mercury trade will continue in the international market. The situation
raises the question of whether mercury compounds could be exported from the United States
for subsequent processing into elemental mercury in other countries.
There are two possible sources of material in the United States for development of compounds
that can be exported to make elemental mercury available abroad:
1. Compounds that already exist in the U.S. market, either as manufactured products,
byproducts of mining and industrial processes, or in industrial waste, could potentially
be exported and then converted to elemental mercury.
4 Mercury(II) sulfide as cinnabar ore is abundant in the European Union. In the U.S., however, mercury(II) sulfide is
primarily a manufactured compound.
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2. Under certain economic conditions, surplus elemental mercury could potentially be
used to manufacture large volumes of mercury compounds in the United States, which
could then be exported and reprocessed outside the United States to regenerate the
elemental mercury.
Manufacture and export of mercury compounds in volumes sufficient to provide a
supplemental source of elemental mercury would most likely focus on compounds that are
readily available or easily generated, stable, transportable, and readily converted back into
elemental mercury. Chemical processes ideally suited to this end will utilize inexpensive,
readily available reagents, and simple procedures and equipment. In short, to be economically
feasible, the total process of manufacture, export, and reprocessing of compounds to regenerate
elemental mercury must be competitive with the price of elemental mercury.
1.1.6 Statutory Requirements of the Report to Congress on Mercury Compounds
The requirement to submit the Report to Congress on Mercury Compounds, as contained in
Section 4 of MEBA, reads as follows (with bold and underlining added to identify key elements
of the report):
REPORT TO CONGRESS ON MERCURY COMPOUNDS -
(A) REPORT- Not later than one year after the date of enactment of the Mercury
Export Ban Act of 2008, the Administrator shall publish and submit to Congress a
report on mercuric chloride [i.e., mercury(II) chloride], mercurous chloride or
calomel, [i.e., mercury(I) chloride], mercuric oxide, [i.e., mercury(II) oxide] and other
mercury compounds, if any, that may currently be used in significant quantities in
products or processes. Such report shall include an analysis of
(i) the sources and amounts of each of the mercury compounds imported into
the United States or manufactured in the United States annually;
(ii) the purposes for which each of these compounds are used domestically, the
amount of these compounds currently consumed annually for each purpose, and
the estimated amounts to be consumed for each purpose in 2010 and beyond;
(iii) the sources and amounts of each mercury compound exported from the
United States annually in each of the last three years;
(iv) the potential for these compounds to be processed into elemental mercury
after export from the United States; and
(v) other relevant information that Congress should consider in determining
whether to extend the export prohibition to include one or more of these mercury
compounds.
(B) PROCEDURE- For the purpose of preparing the report under this paragraph, the
Administrator may utilize the information gathering authorities of this title,
including sections 10 and 11.
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1.2 Purpose of the Report
This report fulfills the requirement for the Report to Congress on Mercury Compounds under
Section 4 of MEBA. It:
provides the information available on sources, amounts, and uses of mercury compounds;
assesses the potential for these compounds to be processed into elemental mercury after
export from the United States; and
as required, conveys information for Congress to consider in determining whether to
extend the export ban to include one or more mercury compounds.
1.3 Report Organization
This report is organized by the sequence of topics in MEBA (see Section 1.1.6). A text box that
maps to the requirements in the Act accompanies each relevant section of this report. There are
five chapters in addition to the introduction: Chapter 2, Selection of Mercury Compounds and
Discussion of Data Availability; Chapter 3, Sources, Uses, and International Trade; Chapter
4, Potential for Export of Mercury Compounds To Be Used as a Source for Elemental Mercury;
Chapter 5, Other Relevant Information to Assist Congress in Determining Whether to Extend
the Export Ban; and Chapter 6, Report Conclusions These chapters are followed by four
appendices: Appendix A presents summary information about the mercury compounds
addressed in this report, Appendix B describes how EPA's Inventory Update Reporting (IUR)
database was used to identify mercury compounds for in-depth review, Appendix C presents
more detailed information on the individual compounds addressed in this report, and
Appendix D presents more detailed information on the chemistry of mercury compounds.
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2. Selection of Mercury Compounds and Discussion of Data
Availability
2.1 Method of Selecting Mercury Compounds Included in This Report
The compounds examined in this report include all mercury compounds that are produced or
used in the United States in significant quantities. The report focuses in more detail on
compounds that EPA considers to have some potential to be processed into elemental mercury
after export. Over 200 mercury compounds exist in the United States, originating from the
following three sources:
> Manufactured mercury compounds. These include compounds that are specifically
developed as chemical products for use in laboratory settings or in the development of
other products.
> Byproducts. Some mercury compounds are produced during the process of making
other products of value. The primary example is mercury(I) chloride (commonly known
as calomel), which is produced in significant quantities as part of the process of mining
and refining gold at mines, and is used as a raw material for processing to regenerate
elemental mercury. Byproduct compounds can be produced in significant quantities
and are readily available to the market at low or no cost.
> Industrial waste. Several compounds are produced in waste streams generated in the
United States in varying quantities. These wastes may contain only de minimis
concentrations of mercury compounds in which case they would not be likely to be
exported to supply elemental mercury. However, it is theoretically possible that in some
circumstances, wastes with mercury compounds might be exported for conversion to
elemental mercury.
For completeness, EPA also considered naturally occurring mercury compounds in the earth's
crust as well as stockpiled mercury compounds. The ban on exports of elemental mercury could
create an economic incentive to export compounds from these origins.
Excluded from this report are any mercury compounds resulting from coal combustion or
found in manufactured consumer products. EPA did not assess these sources because of
language in the legislative history of MEBA: "the Committee does not intend that this
prohibition [ban on export of elemental mercury] prevent exportation of coal or fly ash, a by-
product of coal combustion, or manufactured consumer products containing elemental
mercury." 5 EPA reasoned that if Congress did not prohibit export of elemental mercury
occurring in manufactured consumer products or materials from coal combustion, then it was
not important to assess the export of mercury compounds in those items at this time.
Furthermore, EPA knows of no use of mercury compounds contained in manufactured
consumer products.
This section explains EPA's process for identifying and evaluating the compounds in this
report. While a range of mercury compounds are manufactured for specific uses, EPA has
s S.Rep. No. 110-477. 2008. Senate Report 110-477 - Mercury Market Minimization Act of 2007. Available online at:
http://frwebgate.access.gpo. go v/cgi-bin/getdoc.cgi?dbname=110_cong_reports&docid=f: sr477.110.pdf
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determined that the most significant quantities of mercury compounds in the United States
occur as byproducts or in waste. In some cases these compounds are currently used as raw
material and converted to elemental mercury. Because MEBA will restrict U.S. elemental
mercury exports, it may become more economically feasible to process and export these
byproduct compounds and regenerate elemental mercury after export. For these reasons, EPA
includes these byproduct or waste compounds in the scope of this report, regardless of the
extent to which they are currently used as compounds. However, wastes containing de minimis
amounts of mercury compounds are unlikely to be candidates for export and conversion to
elemental mercury.
2.1.1 Note on Dental Amalgam
EPA does not address dental amalgam in this report because it is not a compound. Dental
amalgam is a mercury-containing product in which small, individual-use quantities of
elemental mercury are packaged in separate containers from other ingredients and delivered as
a "kit" of separate ingredients to dental offices. The elemental mercury remains separate until
application, at which point it is mixed into an individual application of alloy.
2.1.2 Criteria for Inclusion
EPA used the following criteria to identify mercury compounds for this report:
> MEBA specifically requires the compound to be in the report (mercuric chloride
(identified in the report as Mercury(II) chloride), mercurous chloride (Mercury(I)
chloride), and mercuric oxide);
> At least 25,000 pounds (11,340 kilograms) of the compound was manufactured at a
single site in at least one of the years since 1986, according to the Inventory Update Rule
(IUR) reporting database;
> It was sold in the United States in 2001 and 2004, the two years for which data were
collected for the Interstate Mercury Education and Reduction Clearinghouse database
(IMERC) of the Northeast Waste Management Officials' Association (NEWMOA);
> The compound has potential for export in order to provide a source of elemental
mercury, due to technical ease of production and conversion back to elemental mercury;
or
> The mercury compound is produced in significant quantities as an industrial or mining
byproduct or waste.
Table 2-1 lists the mercury compounds addressed in this report and the criteria for their
inclusion.
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U.S. Environmental Protection Agency
Table 2-1: Mercury Compounds by Criteria for Inclusion in the Report
Compound
Mercury(I) chloride
Mercury(II) acetate
Mercury(II) chloride
Mercury(II) iodide
Mercury(II) nitrate
Mercury(II) oxide
Mercury(II) selenide
Mercury (II) sulfate
Mercury(II) sulfide
Mercury(II) thiocyanate
Phenylmercury(II) acetate
Thimerosal
CAS Number
10112-91-1
600-27-7
7487-94-7
7774_29-0
10045-94-0
21908-53-2
20601-83-6
7783-35-9
1344_48-5
592-85-8
62-38-4
54-64-8
Criteria for Inclusion
1, 2, 3,
4,5
2,3
1,2,3
3
3,4
1,3,4
5
3,4,5
3,5
3
2
3
Legend:
1. Specifically required for this report by MEBA
2. More than 25,000 pounds (11,340 kilograms) were produced at single site in any single reporting year since 1986
3. Manufactured or imported as a specialty chemical
4. Technologically feasible to export and convert to elemental mercury abroad
5. Produced in potentially significant quantities, including as a waste or byproduct
2.2 Data Sources and Limitations
EPA used a variety of sources to collect data on the domestic manufacture, imports, exports,
byproduct production, and occurrence in waste streams of mercury compounds. Most of these
databases have one or more important limitations when used for information on mercury
compounds. In most cases, the limitations are due to the data source having been designed for
other purposes.
2.2.1 Substance Registry Services Database
The Substance Registry Services (SRS) is EPA's central registry for information about regulated
and monitored substances. The SRS identifies any EPA data systems, environmental statutes, or
other sources that contain information about a particular substance. Substances include
chemicals, biological organisms, physical properties, and miscellaneous objects. The SRS
Database was used to identify mercury compounds for inclusion in this report.
2.2.2 Inventory Update Reporting Database
EPA regulations require manufacturers and importers of certain chemical substances included
in the Toxic Substances Control Act (TSCA) Chemical Substance Inventory to report site and
manufacturing information for chemicals (including imported chemicals) manufactured in
amounts of 25,000 pounds (11,340 kilograms) or greater at a single site. The information
reported to EPA is used to support risk screening, assessment, priority setting and management
activities and constitute the most comprehensive source of basic screening-level, exposure-
related information on chemicals available to EPA. There are limitations to using IUR data. The
main limitation is that the IUR database includes only a one-year snapshot of data on chemicals
manufactured, and the reported information relates only to the chemicals manufactured during
that specific year. The database does not contain data on the quantity used in a year or the
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specific uses of each chemical. That is, a chemical that is not manufactured in a particular
reporting year may still be in use, if there are leftover inventories from a previous year. Note
that manufacture of mercury(II) oxide in 2006, the most recent year for which data were
reported, was not sufficient to trigger the need for reporting, but the compound is a potential
intermediate to several chemicals that were reported in the 2006 IUR.
2.2.3 Toxics Release Inventory
The 1986 Emergency Planning and Community Right-to-Know Act (EPCRA) and the 1990
Pollution Prevention Act require facilities to report data on the release and other waste
management quantities of certain chemicals manufactured, processed or used in greater than
certain quantities. These data are made available to the public in the Toxics Release Inventory
(TRI). The current TRI toxic chemical list includes 581 individually listed chemicals and 30
chemical categories. The relevant chemical category for this report is Mercury Compounds,
which "includes any unique chemical substance that contains mercury as part of that chemical's
infrastructure" (U.S. EPA, 2008a). Information reported to the TRI does not distinguish among
individual mercury compounds.
2.2.4 Biennial Reporting System
EPA, in partnership with the states, biennially collects information regarding the generation,
management, and final disposition of hazardous wastes regulated under the Resource
Conservation and Recovery Act of 1976 (RCRA), as amended. RCRA hazardous waste
generation information is obtained from data reported by large quantity generators of RCRA
wastes. EPA obtained data on relevant mercury compounds from the Biennial Reporting
System (BRS) by identifying the waste streams with hazardous waste codes that are classified as
mercury-bearing wastes. Like TRI data, BRS information cannot be broken down into data
pertaining to individual compounds, and BRS does not provide information about the
concentration of elemental mercury or mercury compounds in the reported waste streams. The
most recent BRS data available for this report were the 2005 data.
2.2.5 NEWMOA, IMERC, and the EPA Mercury-Containing Products and Alternatives
Database
IMERC was established in 2001 by NEWMOA to support legislative mercury reduction efforts
and provide a central information source about products that contain mercury. IMERC
maintains a Mercury-Added Products Database of national sales data submitted by
manufacturers and distributors on mercury-added products sold (not produced) in the 14 states
that require such reporting.6 Regulations in these states require manufacturers or distributors
to submit data on the national mercury use in their products, and to provide data updates every
three years, starting in 2001. The most recent data available for this report were the 2004 data.
For this report, EPA used information in the IMERC database on the sales amounts and uses of
mercury compounds in the United States. The reported quantities may be somewhat smaller
than the national total. However, EPA does not consider this to be a serious limitation of the
6 California, Connecticut, Illinois, Louisiana, Maine, Massachusetts, Minnesota, New Hampshire, New Jersey, New
York, North Carolina, Rhode Island, Vermont, and Washington.
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data because it is unlikely that many, if any, mercury compounds are sold only in the 36 states
that are not IMERC members.
IMERC also publishes fact sheets and reports based on the reported data. IMERC's database,
fact sheets, and reports, as well as personal communication with NEWMOA officials, have
contributed to the quantification of domestic mercury compound production and identification
of manufacturers.
IMERC's Mercury-Added Products Database is the primary data source of EPA's Database on
Mercury-Containing Products and Alternatives. IMERC's data are supplemented with other
publicly available information on additional products and non-mercury alternatives. EPA used
its database in conjunction with IMERC's data and reports in determining the domestic market
for mercury compounds.
2.2.6 Data on U.S. Imports and Exports of Mercury Compounds
Data are available on quantities of mercury compounds in the aggregate, but not on individual
compounds. The most comprehensive source of U.S. trade data is the United States
International Trade Commission (U.S. ITC) database called the Interactive Tariff and Trade
Dataweb. It is based on the Harmonized Tariff Schedule (HTS) codes developed by the World
Trade Organization (Table 2-2). The newest HTS codes group all mercury compounds together
for the purpose of tariff identification, and as a result they cannot be used to track trade in
specific mercury compounds, but they can provide limited insights into the total volume of
mercury compounds in trade.
Another source of trade data is the Comtrade database maintained by the United Nations. This
data set contains trade data reported by the statistical authorities of approximately 200
countries or areas, including the United States The Comtrade data set also reports trade data
based on HTS codes, but not at the same level of resolution. The U.S. ITC can report at the 10
digit HTS code level, and Comtrade groups data at the more aggregated six-digit HTS code
level. Recent U.S.-reported data on U.S. trade in mercury compounds are identical in the
Comtrade database and the U.S. ITC database. However, other countries' import and export
data to and from the United States in the Comtrade database differ from data in the U.S. ITC
database.
U.S. ITC data on mercury compound trade are currently included in one HTS code that
encompasses all mercury compounds. Prior to 2007, separate codes were used for a limited
number of specific mercury compound imports, including mercury oxides and mercury
chlorides (including both the mercury(I)- and mercury(II)- forms). Other mercury compounds
were grouped with general chemical compounds that did not include mercury. Due to
inconsistencies in mercury compound trade data reported by the United States and its trading
partners, as well as the lack of detail provided by the current HTS coding scheme (used in both
Comtrade and U.S. ITC databases), accurate tracking of trade in individual mercury compounds
is not possible. This limits the assessment of mercury compound markets and trade. Available
import and export data for mercury compounds are discussed in more detail in Chapter 3.
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EPA also examined other trade data sources, including the Eurostat database, waste import and
export data in the BRS, and waste export reporting required by RCRA regulations. Each of these
sources has limited data related to mercury compounds. For example, Eurostat data do not
specify individual compounds.7 BRS data report bulk quantities of waste by waste streams and
do not provide data on constituent (chemical) concentrations or quantities. Finally, EPA
conducted discussions with individuals involved in international elemental mercury trade, but
these experts were unable to characterize global or U.S. trade in specific compounds.
Table 2-2: HTS Headings Dealing with Mercury and Its Compounds, Preparations, and Products
HTS Headings
and Sub-Headings
2805.40.0000
2852.00
2852.00.1000
2852.00.9000
3815.90
3815.90.2000
3824.90
3824.90.3300
Description
Mercury
Compounds, inorganic or organic, of mercury, excluding amalgams:
mercuric oxide [mercury(II) oxide], mercuric cyanide [mercury(II) cyanide], mercuric
oxycyanide [mercury(II) oxycyanide] and mercuric potassium cyanide [mercury(II)
potassium cyanide]
Other
Reaction initiators, reaction accelerators and catalytic preparations, consisting wholly
inorganic substances:
Of mercury or of molybdenum
of
Chemical products and preparations of the chemical or allied industries, mixtures of two
or more inorganic compounds:
Of mercury
2.2.7 1997 Report to Congress
In 1997, EPA produced the Mercury Study Report to Congress, fulfilling requirements of the
Clean Air Act, as amended in 1990. The Report provided background information for this
report, and was used to help identify the mercury compounds on which this report focuses.
7 Eurostat's mission is to provide the EU with statistics at a European level so as to enable comparisons between
countries and regions. Eurostat collects data from member states and compiles statistics on a wide array of topics
including structural indicators, employment and social policy indicators, and others.
Report to Congress 11
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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U.S. Environmental Protection Agency
3. Sources, Uses, and International Trade in Mercury Compounds
This chapter profiles the market for mercury compounds in the United States. Limited
compound-specific information exists with respect to the quantities manufactured, imported,
exported, or used. Therefore, aggregated data and information on mercury compounds are
presented when disaggregated data (as requested in MEBA) are not available.
3.1 Sources and Amounts of Mercury Compounds
Imported or Manufactured
Sources (supply) of mercury compounds include imports,
production for commerce, byproducts and waste, existing
stockpiles, and naturally occurring deposits. This section of the
report identifies the sources of mercury compounds in the United
States and, where available, the quantities of mercury compounds
that come from these sources.
Crosswalk to Requirements in the Mercury
Export Ban Act
i. Sources and amounts imported or
manufactured
3.1.1 Mercury Compounds Imported Into the United States
Import data on mercury compounds are of limited use for this report for two reasons. First,
data currently address only aggregated quantities of all mercury compounds, and do not track
individual compound quantities; though disaggregated import data for some classes of mercury
compounds ("mercury chloride" and "mercury oxide") are available prior to 2007.8 Second,
even total quantities of mercury compounds are uncertain due to conflicting estimates reported
by (1) the U.S. International Trade Commission (U.S. ITC) Interactive Tariff and Trade Dataweb,
and (2) U.S. trade partners reporting to the United Nations Commodity Trade Statistics
Database (Comtrade). The quantity and value of U.S. imports for 2007 and 2008, as reported on
February 15, 2009, are shown in Table 3-1. Quantities reported from the two sources are shown
side-by-side for ease of comparison.
8 These data did not distinguish between mercury(II) chloride and mercury(I) chloride.
Report to Congress 12
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U.S. Environmental Protection Agency
Table 3-1: Quantity and Value of U.S. Imports of Inorganic and Organic Mercury Compounds, by
Trade Database Source, 2007-2008
Country
Germany
Canada
United Kingdom
China
France
Spain
Malaysia
India
Mexico
Belgium
Others
Total
Year
2007
2008
2007
2008
2007
2008
2007
2008
2007
2008
2007
2008
2007
2008
2007
2008
2007
2008
2007
2008
2007
2008
2007
2008
U.S. ITC
Metric Tons
124
118
384
339
72
less than 1
97
20
less than 1
less than 1
11
2
164
22
1
1
less than 1
2
less than 1
less than 1
26
less than 1
880
504
Thousands of Dollars
$441
$520
$163
$92
$463
$80
$220
$70
$6
$64
$215
$61
$161
$50
$32
$39
$2
$36
$76
$24
$474
$21
$2,254
$1,058
Comtrade
(U.S. imports as reported as exports by
U.S. trading partners)
Metric Tons
2
2
555
339
47
less than 1
a
a
a
a
a
a
a
a
a
a
a
a
171
less than 1
379
8
1154
348
Thousands of Dollars
$160
$174
$406
$91
$571
$5
a
a
a
a
a
a
a
a
a
a
a
a
$242
$1
$4,751
$213
$6,130
$485
a. Data were not available for the given year and country.
Data extracted from U.S. ITC and Comtrade on May 11, 2009.
It is not known why recent reported quantities of imported mercury compounds are an order of
magnitude larger than what appears necessary to satisfy domestic U.S. demand (see section
3.2). One possibility supported by older U.S. ITC data is that imported mercury compounds are,
in fact, byproduct materials imported solely for the retort of elemental mercury for re-sale on
the global market. Alternatively, observed increases in the quantity of mercury compounds
could reflect changes in reporting due to changes made to HTS codes in 2007.9
Prior to 2007, the U.S. ITC harmonized tariff system specifically tracked a subset of mercury
compounds: mercury oxides (HTS 2825904500) and mercury chlorides (HTS 2827392000).10
Other mercury compounds were included in broader metals categories, and data for imports of
these compounds are not available. After 2006 mercury(II) oxides and mercury cyanide
9 Observed increases could also reflect imports of mercury compounds that are subsequently re-exported for sale
abroad, either as raw compounds or as value-added products.
10 These data did not distinguish between mercury(II) chloride and mercury(I) chloride.
Report to Congress
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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October 14,2009 U.S. Environmental Protection Agency
compounds are aggregated into one code (HTS 2852001000) and all other mercury compounds
are aggregated into another code (HTS 2852009000) (see Table 2-2, above). Import data for
mercury oxides from 2002-2006 (as well as aggregated mercury(II) oxide and mercury cyanide
compound data from 2007 and 2008) indicate that average annual imports are less than one
metric ton, and do not show any significant trends. In contrast, mercury chloride imports from
2002-2006, including any chloride of mercury, (e.g., as mercury(II) chloride and mercury (I)
chloride), averaged more than 250 metric tons per year, and showed significant increases after
2003. This pattern was dominated by imports from Chile of 410, 654, and 112 metric tons in
2004, 2005, and 2006, respectively.11
The U.S. ITC data from 2002 to 2006 suggest that mercury(I) chloride represented the bulk of
mercury compound imports, though mercury(I) chloride imports from Chile have ceased since
2006. The data seem to show aggregate imports of mercury compounds from Canada, which
had not exceeded 22 metric tons prior to 2007, increased dramatically in 2007 and 2008. It is not
possible to determine whether recent imports from Canada are mercury(I) chloride, because
newer U.S. ITC harmonized tariff codes do not specify mercury chlorides. If recent imports
from Canada are of mercury(I) chloride, then the compound may originate from air pollution
control processes at metals mines, or it may be imported to Canada from other regions before
import to the United States Taken together, recent historical data suggest that mercury(I)
chloride is likely the primary mercury compound imported into the United States, though data
do not allow confirmation of this trend. Furthermore, observed increases in aggregated
reported quantities could reflect changes in reporting.
3.1.2 Commercial Products Manufactured Domestically and Abroad
Only a small quantity of mercury compounds is produced for commercial use, which suggests
that the producers of these mercury compound products are primarily specialty chemical
producers producing small batches. It is not likely that these producers of high-value-added
products currently have the production capacity to produce low-cost bulk mercury compounds,
and it is therefore unlikely that these manufacturers would produce large-volume mercury
compounds specifically to export them for the retort of elemental mercury.
Table 3-2 presents the quantity of mercury compounds sold commercially in the United States
in 2001 and 2004, based on information reported to the IMERC database. Note that these data
include mercury compounds sold commercially, including products manufactured abroad.
The table shows national sales data reported by manufacturers that sell products in any of the
14 States that require reporting. The amounts may be less than actual national totals. (See
section 2.2.5 for discussion of this data limitation.) The compounds sold are divided into three
categories:
> Mercury compound products - mercury compounds sold as products, such as laboratory
chemicals
11 Participants at the 2007 EPA stakeholder meetings on commodity mercury confirmed that these imports from
Chile were mercury(I) chloride from gold mining operations, and were imported for recovery of elemental mercury
(Lawrence, 2007; Pollara, 2007).
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U.S. Environmental Protection Agency
> Products containing a mercury compound as a preservative - products that contain a mercury
compound such as thimerosal12 that acts as a preservative or antifungal agent, but is not
the main ingredient of the product
> Mercury compounds in a value-added kit or product - products that contain a mercury
compound either as part of a chemical test kit or as an ingredient in another value-
added chemical product, wherein the mercury compound is not the main ingredient.
Note that the manufacturers of products that contain mercury compounds may not be the
original manufacturers of the mercury compounds themselves. Thus, the total quantities of
mercury compounds shown in Table 3-2 may include some double counting.
Table 3-2: Quantities of Mercury Compounds Sold in the United States (kilograms)
Category
Mercury Compound Products
Mercury(I) chloride
Mercury(II) acetate
Mercury(II) chloride
Mercury(II) iodide
Mercury(II) nitrate
Mercury(II) oxide
Mercury (II) sulfate
Mercury(II) sulfide
Mercury(II) thiocyanate
Phenylmercury(II) acetate
Mercury(II) selenide
Thimerosal
All other compounds
Products Containing a Mercury Compound as a Preservative
Mercury Compounds in a Value- Added Kit or Product
Total
2001
500.4
8.1
22.9
101.9
14.7
104.3
26.7
133.8
1.0
4.5
0.2
unknown
unknown
82.3
5.5
202.4
708.3
2004
563.3
1.3
41.3
76.8
11.3
88.7
32.5
260.8
0.6
6.4
0.2
unknown
unknown
43.4
56.4
276.8
896.5
Note: Values Include only the amounts of mercury compounds reported to NEWMOA by manufacturers and member states. The
data may not Include the entire universe of mercury-added products.
Source: NEWMOA
Table 3-2 shows larger quantities of mercury compounds reported as sold in 2004 compared
with 2001. However, this does not necessarily imply that the use of mercury compounds is
increasing. The larger numbers in 2004 could be a result of better reporting rates and/or
additional NEWMOA member states in 2004. In addition, the listing of individual mercury
compound products shows that the overall increase in individual compounds sold was driven
by an increase in the reported amount of mercury(II) sulfate sold. The increase in the amount of
mercury(II) sulfate sold was primarily driven by larger sales of chemical oxygen demand (COD)
test kits that contain the compound. The reported quantities for most other mercury compounds
were lower in 2004 compared to 2001.
Table 3-3 presents a list of manufacturers that reported the manufacture of mercury compounds
or products containing mercury compounds to NEWMOA in 2004. Manufacturers are divided
12 Thimerosal is the common name for sodium ethylmercurithiosalicylate. For simplicity, this document uses the common
name for this compound.
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Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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October 14, 2009
U.S. Environmental Protection Agency
into the same three categories as mercury compounds; note that the manufacturers of "products
containing a mercury compound as a preservative" and "mercury compounds in a value-added
kit or product" may not be the original manufacturers of the mercury compounds themselves.
Table 3-3: Firms Reporting Manufacture of Mercury Compounds in the United States, 2004
Manufacturer
Abbott Laboratories
AccuStandard, Inc.
Alfa Aesar, A Johnson Matthey Company
Aquarium Pharmaceuticals, Inc.
Arlington Scientific
BD Biosciences
BD Diagnostic Systems
BioGenex Laboratories, Inc.
Biokit USA, Inc.
BioMerieux, Inc.
Bio-Rad Laboratories, Inc.
CHEMetrics, Inc.
Chemicon International
Dade Behring, Inc.
Dexsil Corp.
Diagnostic Products Corp.
EMD Chemicals, Inc.
Hach Company
Instrumentation Laboratory Co.
Inverness Medical Innovation (Binax, Inc.)
Jackson ImmunoResearch Laboratories, Inc.
Mallinckrodt Baker, Inc.
Palintest Limited
Poly Scientific R&D Corp.
R&D Systems, Inc.
Remel Incorporated
Rowley Biochemical Inc.
Santa Cruz Biotechnology, Inc.
Stearns, Inc.
TechLab, Inc.
Mercury
Compound
Products
^
^
/
/
Products Containing
a Mercury
Compound as a
Preservative
^
,/
,/
/
^
,/
/
^
/
^
/
^
/
/
^
/
/
^
/
/
Mercury
Compounds in a
Value- Added Kit
or Product
^
/
^
^
/
^
/
^
/
/
^
/
^
Note: Table Includes only mercury compound manufacture reported to NEWMOA by manufacturers and member states. The data
may not include the entire universe of mercury-added products.
Source: NEWMOA
Four manufacturers reported sale of "mercury compound products" to IMERC: Alfa Aesar,
EMD Chemicals, Hach Company, and Mallinckrodt Baker. Table 3-4 presents the compounds
identified as produced by each of these manufacturers in 2001 and 2004.
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U.S. Environmental Protection Agency
Table 3-4: Mercury Compounds Manufactured in the United States in 2001, 2004
Compound
Mercury(I) chloride
Mercury (II) acetate
Mercury(II) chloride
Mercury(II) iodide
Mercury (II) nitrate
Mercury (II) oxide
Mercury(II) selenide
Mercury(II) sulfate
Mercury(II) sulfide
Mercury (II)
thiocyanate
Phenylmercury(II)
acetate
Thimerosal
Other mercury
compounds a
Alfa Aesar
2001
^
/
^
^
/
^
/
/
^
^
/
/
2004
S
/
^
,/
/
^
/
/
^
S
/
/
EMD Chemicals
2001
/
2004
/
S
S
/
S
/
S
/
Hach Company
2001
/
/
S
2004
/
/
S
Mallinckrodt Baker
2001
S
/
S
S
/
S
/
S
2004
^
/
S
S
/
S
/
S
Note: Table includes only mercury compound manufacture reported to NEWMOA by manufacturers and member states. The
data may not include the entire universe of mercury-added products.
a Other Mercury Compounds (as of 2004): Alfa Aesar mercury(II) cyanide, mercury(II) fluoride, mercury (I) nitrate, mercury(II)
perchlorate, mercury(II) telluride, mercury(II) trifluoroacetate, mercury(II) trifluoromethanesulfonate, mercury potassium
iodide, mercury tetrathiocyanatocobaltate, methylmercury(II) chloride, methylmercury(II) hydroxide, phenylmercury chloride,
phenylmercury nitrate, dibenzyl mercury, diphenyl mercury, ethylmercury chloride; EMD Chemicals P-Aminophenylmercuric
Acetate
Source: NEWMOA
3.1.3 Byproducts
Several mercury compounds can be produced as byproducts of industrial processes, including
gold mining and sulfide ore roasting. Production of mercury compound byproducts is
frequently due to processes designed to remove mercury from other substances, such as mining
ores, natural gas, or flue or smelter gases to prevent air pollution. To the extent that these
compounds are processed to regenerate elemental mercury, the value of these materials is likely
to be affected by the export ban. In other industrial processes where elemental mercury is a
component of (and sometimes regenerated from) industrial waste streams, the mercury
compounds generated are typically referred to as wastes.
Mercury(I) chloride and elemental mercury are produced in relatively large quantities as a
byproduct of gold mining. Chapter 4 addresses mercury(I) chloride in the context of the export
ban, when the elemental mercury converted from the mercury(I) chloride can no longer be sold
abroad.
Mercury(I) chloride, mercury(II) sulfate, mercury(II) sulfide, and mercury(II) selenide are all
produced during sulfide ore roasting, as discussed in Section 3.1.3.2. However, the specific
quantities of byproduct mercury compounds generated from sulfide ore roasting and the
mining of other metals are not readily available.
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Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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3.1.3.1 Gold Mining and Mercury Compound Generation (Mercury(I) Chloride)
In the processing of refractory and low-grade ores, gold extraction is accomplished by treating
the ore with cyanide under alkaline conditions. The gold cyanide that leaches out is then sorbed
onto activated carbon. Soluble mercury(II) cyanides (Hg(CNh, Hg(CN)s-, and Hg(CN)42') are
also formed in the leachate and are captured by the activated carbon. Typically, the mercury on
the filter material is retorted to regenerate elemental mercury. Alternatively, these soluble
mercury(II) cyanide compounds can be converted into insoluble compounds, such as
mercury(II) sulfide, by the addition of calcium sulfide or sodium sulfide to the leachate. The
insoluble mercury compounds precipitate out prior to the sorption step. Other precipitating
agents include the dialkyldithiocarbamates (typically potassium dimethyldithiocarbamate),
which form mercury carbamate precipitates. The carbamates tend to be more stable than
mercury(II) sulfide under the alkaline conditions required for cyanide leaching (Tessele et al.,
1998). At least one gold mine in Nevada has reported using the carbamate technology (Jones
and Miller, 2005). A bioremediation process (the Biocyanide process) for the conversion of
mercury cyanides to mercury(II) sulfide in gold cyanide leachates has also been demonstrated
on a pilot scale. Mercury cyanide solution is passed over a reactor bed made of a porous
ceramic medium that is coated with a proprietary biofilm (U.S. EPA, 2007a).
Mercury is also regenerated from the gold processing roasters through air pollution control
mechanisms. The most common procedure utilizes mercury(II) chloride in a scrubber, where
the mercury(II) chloride reacts with volatilized elemental mercury to form mercury(I) chloride.
In Nevada, the greatest amount of byproduct mercury recovered for sale pre-2005 in the United
States came from the Barrick mines in Nevada.
Current regulations do not prohibit the export of mercury(I) chloride. Import data suggests that
mercury recyclers are willing to purchase mercury(I) chloride, and one mercury recycler
advertises services for converting mercury (I) chloride to elemental mercury, suggesting that this
is an economically viable business. Therefore, it may also be economically feasible to export
mercury(I) chloride for the purpose of converting it into elemental mercury in countries outside
the United States.
Nevada Gold Mining
Approximately 80 percent of the gold produced in the United States comes from gold mines in
Nevada. In 2002, Nevada instituted the Voluntary Mercury Reduction Program (VMRP), which
sought to reduce mercury air emissions through voluntary addition of emission controls. The
four Nevada gold mining companies with the greatest mercury emissions participated in the
VMRP:
> Barrick Gold Corporation: Goldstrike Mining Operations
> Newmont Mining Corporation: Gold Quarry Operations Area; Twin Creeks Mine
> Placer Dome: Cortez Gold Mine Pipeline Mining Operation
> Queenstake Resources, Ltd.: Jerritt Canyon Mine
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U.S. Environmental Protection Agency
The participants in the VMRP are thought to comprise more than 90 percent of the mercury air
emissions reported in EPA Region 9 in 2000. Through the VMRP, the participants reduced their
mercury emissions by over 80 percent, leading to greater amounts of mercury byproduct
captured (State of Nevada, 2006; NAC 445B.3653, 2006).
The four major Nevada gold mining companies voluntarily reported their total mercury
byproduct for the years 1999-2003 (partial). Table 3-5 presents the mercury byproduct of the
four major companies; the data include both elemental mercury and mercury(I) chloride
combined; the amount of mercury(I) chloride cannot be determined except in the case of the
Barrick Goldstrike mine, but this is the largest of the two gold mines in the United States
producing mercury(I) chloride using the Boliden-Norzink process. Barrick staff provided Jones
and Miller with a breakdown of their byproduct production, which is presented in Table 3-6.
Table 3-5: Total Mercury Byproduct Recovered for Sale (metric tons elemental mercury)
Queenstake (Jerritt Canyon)
Placer Dome (Cortez)
Barrick (Goldstrike)
Newmont (Gold Quarry and Twin Creeks)
Total
1999
1.8
0.9
6.2
n/a
2000
2.0
0.5
26.1
6.4
35.0
2001
1.7
0.5
55.4
12.5
70.0
2002
2.3
0.4
82.6
11.5
96.8
2003
(partial)
-
0.4
-
13.1
-
Source: Jones and Miller, 2005
Table 3-6: Mercury Recovered at the Barrick Goldstrike Mine (metric tons elemental mercury)
Elemental Hg, Refinery
Elemental Hg, Roaster
Mercury(I) chloride, Roaster
1999
6.2
2000
9.8
0.6
15.8
2001
11.6
13.5
30.2
2002
9.2
13.1
60.3
Source: Jones and Miller, 2005
As Table 3-6 shows, the quantity of elemental mercury recovered in mercury(I) chloride in the
early 2000s exceeded the quantity of elemental mercury recovered, and in 2002 was produced in
excess of 60 metric tons.
The Nevada gold mining companies generally sell their byproducts (elemental mercury and
mercury(I) chloride) to recycling companies (Jones and Miller, 2005). These byproducts are not
considered a waste, and therefore are not reported to the BRS or TRI databases. Table 3-7 lists
the recycling companies to which three of the four major mining companies have sold their
byproduct mercury.
Table 3-7: Nevada Gold Mine Mercury Byproduct Sales to Recycling Companies
Mining Company
Barrick (Goldstrike)
Cortez (Placer Dome)
Newmont
Recycling Company
Bethlehem Apparatus
Mercury Waste Solutions
D.F. Goldsmith Chemical and Medical Corp.
Recycling Company Location
Bethlehem, PA
Union Grove, WI
Evanston, IL
Source: Jones and Miller, 2005
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Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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U.S. Environmental Protection Agency
Reporting of air emissions of mercury and mercury byproduct from gold mines in Nevada
changed after 2005. In March of 2006, the State of Nevada passed the Nevada Mercury Control
Program (NMCP), which superseded and replaced the VMRP. Effective May 4, 2006, the NMCP
stipulates that "owners or operators that operate, construct or modify a thermal unit that emits
mercury must apply for, and obtain, a Mercury Operating Permit to Construct (Mercury OPTC)
to apply the NvMACT (Nevada maximum achievable control technology)" (State of Nevada,
2006, p. 2). The NMCP also includes a requirement to report any mercury co-product on an
annual basis (NAC 445B.3611-3689); mercury co-product is defined as "any mercury which is
collected from the site of a stationary source that conducts precious metals mining for shipment
to another location to be sold or recycled" (NAC 445B.3619). The Nevada Division of
Environmental Protection (NDEP) indicates that "co-product" includes elemental mercury as
well as mercury contained in any other substrate, such as mercury (I) chloride (NDEP, 2009).
Table 3-8 lists the annual quantities of mercury co-product reported in 2006 and 2007. Reported
quantities of mercury byproducts cannot be broken out by elemental mercury and mercury
compounds.
Table 3-8: Annual Mercury and Mercury Compound Byproduct Reported under the Nevada Mercury
Control Program (metric tons)
Source
Newmont Mining Corporation - Twin Creeks Mine
Queenstake Resources USA, Inc - Jerritt Canyon Mine
Newmont Mining Corporation - Gold Quarry
Barrick, Bald Mountain Mine - Huntington Valley
Kennecott Rawhide Mining Company - Denton-Rawhide
Mine
Cceur D' Alene Mining Corporation - Coeur Rochester Mine
Barrick Gold Corporation, Cortez Gold Mines
Florida Canyon Mining, Inc. - Florida Canyon Mine
Round Mountain Gold Corporation - Smoky Valley
Common Operation
Homestake Mining Company - Ruby Hill Project
Marigold Mining Company - Marigold Mine
Barrick Goldstrick [sic] Mines, Inc.
Total
Permit
AP1041-0723.01
API 041-0778
API 041-0793
AP1041-1362
API 041-1116.02
AP1044-0063.02
AP1041-2141 (Consolidated
Title V Permit)
AP1041-0106.02
API 041-0444.01
API 041-0713.01
AP1041-0158.02
AP1041-0739.01
2006
8.1
2.7
2.5
2.7
0.1
14.6
0.1
0.2
0.0
0.5
0.2
89.4
120.9
2007
12.0
0.9
3.1
2.1
0.0
14.0
0.3
0.0
0.0
0.3
0.2
53.2
86.1
Sources: Nevada Bureau of Air Pollution Control, 2006 and 2007
Table 3-8 illustrates the decrease in total mercury byproduct that Barrick representatives
identified in the last few years, from more than 80 metric tons in 2006 to 53 metric tons in 2007.
Though the overall decrease in mercury byproduct production is primarily attributable to a
reduction at the Barrick Goldstrike Mines, mercury byproduct production in 2007 was in line
with byproduct production in 2002 (see Table 3-6 above). Barrick representatives estimate that
2008 production of mercury(I) chloride at the Goldstrike mine contained roughly 25 metric tons
of elemental mercury (Barbanell 2009).
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Gold Mining TRI Data
The 1986 Emergency Planning and Community Right-to-Know Act (EPCRA) and the 1990
Pollution Prevention Act require facilities to report data on the quantities of chemicals released
or otherwise managed as waste. These data are made available to the public in the Toxics
Release Inventory (TRI). Table 3-9 presents 2007 TRI mercury compounds data for the gold ore
mining industry. Gold Ore Mining, NAICS 212221, is comprised of establishments primarily
engaged in developing the mine site, mining, and/or preparing ores valued chiefly for their
gold content.
Facilities in the Gold Ore Mining industry reported more than two million kilograms of on-site
land releases of mercury compounds in 2007. This large quantity appears to reflect mercury
content in waste rock or tailings containing mercury compounds. In 2007, more than 20,000
kilograms of mercury compounds were reported as recycled on- and off-site; the guidelines for
reporting on- and off-site recycling are somewhat different. On-site recycling includes only the
quantities of mercury compounds actually regenerated for reuse, not the total amount of the
toxic chemical in the waste stream entering recycling units on-site. The opposite is true for off-
site recycling, which includes all amounts of the toxic chemical intended to be recycled and sent
off-site for that purpose, not just the amount of the toxic chemical (i.e., mercury compound or
elemental mercury) actually regenerated (U.S. EPA, 2009b). These definitions indicate that the
23,147 kilograms reported to have been recycled on-site is the actual amount of mercury
compounds regenerated for reuse, which should not include any waste rock. Conversely, the
2,084 kilograms reported to have been recycled off-site is too small a number to account for
mercury in mercury(I) chloride from gold mines. TRI reports show that gold mines did not
report mercury(I) chloride sent to mercury recyclers over the last decade because this byproduct
is not considered to be a waste for purposes of TRI.
Report to Congress 21
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October 14,2009 U.S. Environmental Protection Agency
Table 3-9: TRI Report of Mercury Compound Waste Quantities Reported by Gold Ore
Mining Industry for 2007(kilograms mercury)
Facility Count
Total Releases
Total Air Releases
Surface Water Discharges
Underground Injection
Total Land Releases
Total Waste Managed
Recycled On-site
Recycled Off-site
Quantity Released On- and Off-site
212221
Gold Ore Mining
20
2,758,149
1,485
0
0
2,756,727
2,783,445
23,147
2,084
2,758,146
Notes:
> Total Air Releases are the sum of fugitive air emissions and stack or point source air emissions. Fugitive air
emissions are all releases to air that are not released through a confined air stream. Stack or point source air
emissions occur through confined air streams such as stacks, vents, ducts, or pipes.
> Total Land Releases includes releases of toxics to RCRA Subtitle C landfills, other landfills, land treatment,
RCRA Subtitle C Surface Impoundments, other surface impoundments, and other land disposal.
> Recycled On-site is the total amount of the toxic chemical recycled on-site; this includes only the amount of the
toxic chemical actually regenerated for reuse, not the total amount of the toxic chemical in the waste stream
entering recycling units on-site.
> Recycled Off-site is the total amount of the toxic chemical sent off-site for recycling; this includes all amounts of
the toxic chemical intended to be recycled and sent off-site for that purpose, not just the amount of the toxic
chemical actually regenerated.
> Quantity Released On- and Off-site includes 1). total on-site disposal to Class I Underground Injection Wells,
RCRA Subtitle C landfills, and other landfills; 2). total other on-site disposal or other releases; 3). total off-site
disposal to Class I Underground Injection Wells, RCRA Subtitle C landfills, and other landfills; and 4). total
other off-site disposal or other releases.
Source: U.S. EPA 2009b., TRLNET, http://www.epa.gov/triexplorer Orginal reporting in Ibs
3.1.3.2 Sulfide Ore Roasting and Mercury Compound Generation (Mercury(I) Chloride,
Mercury(II) Sulfate, Mercury(II) Sulfide, and Mercury(II) Selenide)
Mercury is found in sulfide ores that are processed to isolate other metals in addition to gold;
notably, silver, lead, zinc, and copper. Mercury contained in sulfide ores can be separated from
other materials in the form of mercury(I) chloride, mercury(II) sulfate, mercury(II) sulfide, and
mercury(II) selenide during roasting and smelting, and may deposit on the fly ash, dust, and
slag generated in these processes. Detailed information on the distribution or quantities of
mercury in these wastes is not available (Jasinski, 1994). Roasting and smelting sulfide ores
generates sulfur dioxide, which is captured and converted to sulfuric acid prior to venting the
stack gases to the atmosphere. A significant amount of the mercury generated during roasting is
also emitted to the stack gases and contaminates the refined metal ores with sulfuric acid unless
the mercury is removed from the stream. Several processes for mercury control are in use,
including the Boliden-Norzink process and the Outokumpu process (Louie, 2005).
3.1.4 Mercury Compounds in Waste
EPA investigated whether industrial wastes containing mercury compounds are possible
sources for export and subsequent conversion to elemental mercury. The information gathered
Report to Congress 22
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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October 14,2009 U.S. Environmental Protection Agency
suggests that the low mercury concentrations in most wastes containing mercury compounds
make their export for the purpose of producing elemental mercury unlikely.
Under RCRA, hazardous wastes are either "listed" as particular waste streams (e.g., brine
purification muds from mercury cell chlor-alkali plants) or are classified as "characteristic"
wastes based on toxicity of single constituents (e.g., mercury), ignitability, reactivity, or
corrosivity.
The following hazardous, mercury-bearing wastes may contain mercury in a compound form:
> D009 Wastes: Characteristic mercury wastes
D009 wastes contain mercury in the leachate from the waste (using the Toxicity
Characteristic Leaching Procedure) at a concentration in the extract greater than or
equal to 0.20 mg/L (roughly 0.20 ppm). These wastes are variable in composition,
and can include used fluorescent bulbs, batteries, switches, and thermometers, as
well as wastes from production of organomercury compounds using mercury(II)
chloride catalysts or miscellaneous wastes from chlor-alkali production facilities
(U.S. EPA, 1990).
D009 wastes' mercury concentrations are generally below 2.7 percent, except for
mercury(II) oxide waste generated from battery recycling, which may have mercury
concentrations exceeding 90 percent (U.S. EPA, 1990). Note that mercury(II) oxide
waste from battery recycling is an unlikely candidate for export as an alternative to
elemental mercury, because mercury oxide batteries are no longer widely used and
the waste is generated in small quantities (U.S. EPA, 2009c).
There are two subcategories of D009 waste: high concentration mercury subcategory
and low-concentration subcategory. RCRA regulations require that D009 wastes in
the first subcategory are roasted or retorted to recover the elemental mercury.
> K071 Wastes: Brine purification muds from the mercury cell process in chlorine
production, where separately prepurified brine is not used (U.S. EPA, 1990).
K071 wastes generally contain less than 100 parts per million mercury content,
which is typically metallic mercury or mercury(II) chloride. The best demonstrated
available technology (BDAT) to regenerate mercury from K071 wastes is to use a wet
process (U.S. EPA, 1990).
> K106 Wastes: Wastewater treatment sludge from the mercury cell process in chlorine
production
K106 wastes typically contain mercury at a concentration greater than 260 mg/kg
(260 parts per million, or 0.026 percent) for which roasting or retorting is required.
Mercury is generally in elemental form or as mercury(II) sulfide. K106 wastes are not
likely to have mercury concentrations above 16 percent (U.S. EPA, 1990).
> P065 Wastes: Mercury fulminate
P065 wastes contain discarded or off-specification mercury fulminate, as well as
container or spill residue. P065 waste requires incineration, regardless of total
mercury content.
Report to Congress 23
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October 14,2009 U.S. Environmental Protection Agency
> P092: Phenylmercury acetate
P092 wastes contain discarded or off-specification phenylmercury acetate product, as
well as container or spill residue. P092 waste requires incineration, roasting or
retorting.
Mercury compound wastes are generated from two main processes: (1) those in which
elemental mercury and/or mercury compounds are utilized for large-scale chemical production
processes, and (2) remediation of contaminated soils, effluents, ground water, and flue gases.
3.1.4.1 Mercury Compound Wastes from the Chlor-Alkali Manufacturing Process
Historically, three large-scale chemical production processes have employed elemental mercury
or mercury compounds. These include the production of chlorine and caustic soda (the chlor-
alkali process), the manufacture of vinyl chloride from acetylene, and the manufacture of
acetaldehyde from acetylene. In the United States today, only the chlor-alkali industry uses
elemental mercury and generates a mercury compound waste.
The mercury-cell chlor-alkali process is an electrochemical process for the generation of chlorine
gas and sodium hydroxide. Elemental mercury is used as the cathode material, and chlorine is
generated from the brine (sodium chloride) electrolyte/feedstock. During the process, elemental
sodium is produced at the cathode and forms an amalgam with the elemental mercury. The
mercury-sodium amalgam is decomposed with water, forming sodium hydroxide. The
elemental mercury is then recycled back into the process. During the manufacturing process,
some elemental mercury is oxidized and forms mercury chloride compounds and mercury
sulfides. Caustic wastewater sludge from this process typically contains mercury(I) and
mercury(II) chlorides, mercury(II) sulfide, elemental mercury, and mercury species on activated
carbon (U.S. EPA, 2007a).
Typical waste treatment processes involve retorting the sludge to reclaim elemental mercury.
Alternatively, the sludge can be treated with acid, followed by hypochlorite to convert all of the
available mercury to mercury(II) chloride. The mercury(II) chloride can then be washed from
the sludge and precipitated as mercury(II) sulfide (Weiss and Lechugs, 1983; Blanch et al., 1978;
Balco et al., 1977). Removal of elemental mercury from the wastewater can be accomplished by
precipitation with sulfide to produce mercury sulfide (U.S. EPA, 2007a).
The volume of chlor-alkali process waste generated continues to decrease as newer, mercury-
free technology is adopted. The number of chlor-alkali plants in the United States that use the
mercury-cell process decreased from 25 in 1980 to five in 2009 (Chlorine Institute, 2008).
Table 3-10 presents 2007 TRI mercury compounds data for the Alkalies and Chlorine
Manufacturing industry.13 Alkalies and Chlorine Manufacturing, NAICS 325181, is comprised
of establishments primarily engaged in manufacturing chlorine, sodium hydroxide, and other
alkalies, often using an electrolysis process.
13 EPCRA and the 1990 Pollution Prevention Act require facilities to report data on the quantities of chemicals stored
on-site as well as data on waste management. These data are made available to the public in the Toxics Release
Inventory (TRI).
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Facilities in the Alkalies and Chlorine Manufacturing industry reported releases of more than
1,400 kilograms of mercury compounds in 2007, almost entirely to air. The total mercury
compound waste managed, however, was approximately 20,257 kilograms. Of that, 18,119
kilograms of mercury compounds were recycled on-site, indicating that more than 90 percent of
the total waste managed is recycled either on- or off-site. Most likely, the recycled mercury
compounds are used to reclaim elemental mercury to be reused as the cathode in the
manufacturing process.
Table 3-10: TRI Release and Waste Management Data for Mercury Compounds for the Alkalies and
Chlorine Manufacturing Industry (kilograms)
Facility Count
Total Releases
Total Air Releases
Surface Water Discharges
Underground Injection
Total Land Releases
Total Waste Managed
Recycled On-site
Recycled Off-site
Quantity Released On- and Off-site
325181
Alkalies and Chlorine Manufacturing
2
1,438
1,025
7
0
7330
20,257
18,119
696
1,442
Note: Although seven Alkalies and Chlorine Manufacturing facilities reported to TRI in 2007, only two reported mercury
compounds data.
> Total Air Releases are the sum of fugitive air emissions and stack or point source air emissions. Fugitive air emissions are all
releases to air that are not released through a confined air stream. Stack or point source air emissions occur through confined
air streams such as stacks, vents, ducts, or pipes.
> Total Land Releases total releases of toxics to RCRA Subtitle C landfills, other landfills, land treatment, RCRA Subtitle C
Surface Impoundments, other surface impoundments, and other land disposal.
> Recycled On-site is the total amount of the toxic chemical recycled on-site; this includes only the amount of the toxic chemical
actually regenerated for reuse, not the total amount of the toxic chemical in the waste stream entering recycling units on-site.
> Recycled Off-site is the total amount of the toxic chemical sent off-site for recycling; this includes all amounts of the toxic
chemical intended to be recycled and sent off-site for that purpose, not just the amount of the toxic chemical actually
regenerated.
> Quantity Released On- and Off-site includes 1). total on-site disposal to Class I Underground Injection Wells, RCRA Subtitle C
landfills, and other landfills; 2). total other on-site disposal or other releases; 3). total off-site disposal to Class I Underground
Injection Wells, RCRA Subtitle C landfills, and other landfills; and 4). total other off-site disposal or other releases.
Source: U.S. EPA 2009b., TRI.NET, http://www.epa.gov/triexplorer
3.1.4.2 Remediation of Mercury from Contaminated Sites and Effluents
Polluted soils, effluents, ground water, and flue gases contain large volumes of material that
may contain relatively low concentrations of elemental mercury and its compounds. Pollution
remediation processes described in the sections below are designed to concentrate, segregate,
and isolate elemental mercury as inorganic mercury compounds. The resulting materials,
therefore, represent a potential source of elemental mercury or its compounds.
Contaminated Soil and Solids (Soil, Sediment, and Sludge)
Soils and solids contaminated with elemental mercury and mercury compounds can be
chemically treated to convert the mercury to soluble compounds that can be extracted into an
Report to Congress 25
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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October 14,2009 U.S. Environmental Protection Agency
aqueous phase by washing.14 An acid extraction technique has also been demonstrated for the
treatment of chlor-alkali plant waste at both pilot scale and full scale (U.S. EPA, 2007a).
Additionally, soils can be treated with iodine and potassium iodide to convert mercury to a
soluble compound; elemental mercury can then be regenerated from the wash solution by
electrolysis (Foust, 1993,1994).
Contaminated Water and Aqueous Effluents
Treatment options for contaminated liquids include precipitation and sorption techniques.
Precipitation methods convert soluble mercury compounds into insoluble compounds such as
mercury(II) sulfide. Separation of the precipitated compound from suspension in the liquid can
be facilitated by pH adjustment, the addition of flocculants, or the use of sorbents. Mercury
removal by precipitation has been successfully demonstrated at full scale to treat contaminated
ground water at three locations and to treat wastewater at eight locations (U.S. EPA, 2007a).
Membrane filtration methods (microfiltration, ultrafiltration, nanofiltration, or reverse osmosis)
are typically preceded by a precipitation step. Filtration alone will not remove soluble mercury
compounds (U.S. EPA, 2007a).
Sorption methods can capture elemental mercury and mercury compounds from liquid and
gaseous streams. Commonly used sorbents include activated carbon, ion-exchange resins, and
functionalized resins. (U.S. EPA, 2007a). In another process, effluents containing thimerosal
were treated with hypochlorite to convert all of the mercury to mercury(II) chloride, which was
captured on thiol-functional ion exchange resin (Robinson 1992a, 1992b).
Vinyl Chloride Manufacture
Mercury(II) chloride on activated carbon was once used extensively as a catalyst for vinyl
chloride manufacture from acetylene. Spent catalysts can be regenerated by thermal
regeneration or steam desorption to remove mercury. Waste streams from this process are likely
to contain mercury(II) chloride and possibly elemental mercury. This process is still in operation
in some parts of the world, although it has been phased out in Western countries in favor of a
newer technology that uses ethylene as the feedstock and does not require a mercury catalyst
(Rossberg et al., 2006). Because at least one vinyl chloride manufacturer was listed as a source
of mercury-bearing wastes in the United States in the RCRA 2005 Biennial Report, there may be
an export market for mercury(II) chloride to support the process elsewhere, as vinyl chloride is
an important industrial material for making PVC plastics. This was the largest source of
mercury compounds reported in the 2005 Biennial Report.
3.1.4.3 Special Case: Mercury Sulfide Waste
Bethlehem Apparatus, a mercury recycling company in Hellertown, Pennsylvania is developing
a process "that allows the retirement of elemental mercury from future use by stabilizing it into
a form that can be safely land filled."15 This process involves converting elemental mercury into
14 Aqueous oxidative extractants include nitric acid, hypochlorite, and halogens (such as iodine) (Wilhelm, 1999).
Mercury may then be removed from solution by precipitation from the wash phase with the addition of a base or
other precipitating reagent (e.g., sulfide) or the addition of a flocculant.
15 See: http: / /www.bethlehemapparatus. com/ mercury-retirement, html.
Report to Congress 26
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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October 14,2009 U.S. Environmental Protection Agency
mercury(II) sulfide which stabilizes the mercury. It is thus unlikely that the mercury(II) sulfide
produced by Bethlehem Apparatus would be used as an alternative to exporting elemental
mercury, and EPA did not further assess this encapsulated form of mercury(II) sulfide for the
report.
3.1.5 Stockpiles of Mercury Compounds among End-Use Consumers
Mercury compounds have historically been used in agriculture as fungicides, mildewcides and
pesticides. In early 1995, all mercury compound-containing U.S. pesticide registrations were
discontinued. The last four uses to be phased out were turf fungicide, mildewcide for fresh-cut
wood, latex paint fungicide/preservative, and outdoor fabric treatment. As a result, mercury
compound-containing chemicals may be present in stockpiles in farms, golf courses, or other
areas where these uses were expected (Wisconsin Department of Natural Resources, 1997).
These stockpiles are most likely to be scattered at locations where they were previously utilized.
It is unlikely that these mercury compound-containing chemicals will be found in large
quantities.
3.1.6 Naturally Occurring Mercury Compounds
Of the more than 30 minerals that contain mercury, relatively few have been commercially
exploited for their mercury content. Those that have include mercury(II) sulfide (cinnabar,
HgS), metacinnabar (black cinnabar, HgS), mercury sulfide chloride (corderiote Hg3S2Cl2),
native elemental mercury (Hg), and livingstonite (HgSb4S7) (Jasinski, 1994). Mercury(II) sulfide
(cinnabar) is by far the most abundant and commercially important of the mercury-bearing
ores. High-quality ore often contains droplets of elemental mercury. Elemental mercury is
extracted from mercury(II) sulfide (cinnabar) by retorting the ore and condensing the elemental
mercury vapor that is released. Other methods of extraction of elemental mercury from
mercury(II) sulfide (cinnabar) have been reported, including electrolytic methods (e.g., Baxter,
1929), chemical leaching (DeVito and Brooks, 2005), and an ancient method for isolating
elemental mercury by crushing native mercury(II) sulfide (cinnabar) with vinegar in a copper
vessel (Takacs, 2000). Retorting the ore to regenerate elemental mercury has been the preferred
method for centuries, however. Because commercial mercury mining in the United States
ceased with the closure of the last domestic mine in 1992, however, these ores containing
mercury compounds are not coming into the U.S. market in large quantities.
3.1.7 Summary Sources of Mercury Compounds
Table 3-11 summarizes the sources of mercury compounds entering the U.S. market.
Report to Congress 27
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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October 14, 2009
U.S. Environmental Protection Agency
Table 3-11: Domestic Sources of Mercury Compounds in the United States (kilograms)
Compound
Mercury(I) chloride
Mercury(II) acetate
Mercury(II) chloride
Mercury(II) iodide
Mercury(II) nitrate
Mercury(II) oxide
Mercury(II) selenide
Mercury(II) sulfate
Mercury(II) sulfide
Mercury(II) thiocyanate
Phenylmercury(II) acetate
Thimerosal
Other compounds
Total
CAS Number
10112-91-1
1600-27-7
7487-94-7
7774_29-0
10045-94-0
21908-53-2
20601-83-6
7783-35-9
1344_48-5
592-85-8
62-38-4
54-64-8
-
-
Quantity
Sold (2004)
1.3
41.3
76.8
11.3
88.7
32.5
unknown
260.8
0.6
6.4
0.2
unknown
43.4
563.3
Byproduct or Waste
>25,OOOHg
-
-
-
-
-
unknown
unknown
unknown
-
-
-
unknown
unknown
Imported currently
or recent past
Imported in recent
years
-
-
-
-
unknown
-
unknown
-
-
-
unknown
unknown
504,265
"-" indicates not a source
"unknown" indicates is a source but quantity is unknown.
Report to Congress
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
28
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October 14, 2009
U.S. Environmental Protection Agency
3.2 Purposes and Amounts of Mercury Compounds used: Current and Future
3.2.1 Current Uses
Mercury compounds have been used historically, and are
sometimes still used, in batteries, pigments, laboratory
catalysts or reagents, explosives, pharmaceutical applications,
and electrochemistry (Toxnet Hazardous Substances Database,
2008a). Table 3-12 summarizes the purposes for which
mercury compounds are currently used in the United States.
As the table shows, more of the compounds are used in
laboratory chemistry than any other single use.
Crosswalk to Requirements in the Mercury
Export Ban Act
ii. Purposes and amounts consumed
by use: current and future
Table 3-12: Purposes for Which Mercury Compounds Are Used and Amounts Consumed by Use
Compound
Mercury(I) chloride
Mercury(II) acetate
Mercury(II) chloride
Mercury(II) iodide
Mercury(II) nitrate
Mercury(II) oxide
Mercury(II) selenide
Mercury (II) sulfate
Mercury(II) sulfide
Mercury (II)
thiocyanate
Phenylmercuric
acetate
Thimerosal
CAS
Number
10112-91-1
1600-27-7
7487-94-7
7774_29-0
10045-94-0
21908-53-2
20601-83-6
7783-35-9
1344-48-5
592-85-8
62-38-4
54-64-8
Quantity
Sold (kg,
2004)
1.3
41.3
76.8
11.3
88.7
32.5
unknown
260.8
.6
6.4
less than
0.2
unknown
Uses
Electrochemistry
Laboratory chemistry;
Production of
organomercuric
compounds
Laboratory chemistry;
Waste treatment
Laboratory chemistry;
Veterinary medicine;
Nuclear particle
detection
Laboratory chemistry
Laboratory chemistry;
Batteries
Semiconductors
Laboratory chemistry;
Gold and silver
extraction
None
Laboratory chemistry;
Photography
Pharmaceutical;
Production of
phenylmercury
compounds
Pharmaceutical
Availability of Non-Mercury
Alternatives
Alternatives to mercury(I) chloride
electrodes are available, depending
on the application
None for laboratory or other uses
None for laboratory use; Alternative
waste treatment methods are
available, depending on the
application
None for laboratory use; Alternatives
are widely available for veterinary
medicine uses; Alternatives for
nuclear particle detection use
unknown
None for laboratory use
None for laboratory use; Alternatives
are available for battery uses
Unknown
None for laboratory use; Alternatives
are available for gold and silver
extraction use
Semiconductor use banned
None for laboratory use; Alternatives
are widely available for photography
use
Alternatives available for
pharmaceutical use; None for
production of other compounds
Alternatives available for
pharmaceutical use
Report to Congress
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
29
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October 14,2009 U.S. Environmental Protection Agency
3.2.2 Estimated Amounts of Mercury Compounds To Be Used for Each Purpose in 2010 and
Beyond
It is difficult to predict future use of individual mercury compounds for specific purposes
because quantities of compounds are limited and not well tracked. However, some general
trends in use can be identified.
There is some indication that demand for mercury compounds in the United States may decline.
NEWMOA predicts that reductions in mercury compound use are likely in the near future, and
identifies two reasons for possible future reductions: pharmaceutical manufacturers continuing
to eliminate use of thimerosal as a preservative, and laboratory use of mercury compounds
ceasing at educational institutions because of state restrictions on mercury in schools
(NEWMOA, 2008).
Use of mercury compounds in analytical laboratory chemistry is likely to remain approximately
at current levels or to decline. Several mercury compounds have uses as laboratory standards or
analytical reagents for which there seem to exist few or no viable alternatives (Nordic Council
of Ministers, 2007). However, general trends suggest an overall decline in the use of mercury-
containing products in the United States, likely due at least in part to increased awareness of
mercury hazards and increased state regulation of mercury and mercury-containing products.
Production of mercury compounds as byproducts and in wastes will continue in some
industries. In addition, more stringent regulation of waste treatment or air emissions may
increase the quantity of mercury compounds that are removed from power plant emissions,
waste streams, or flue gases resulting from industrial processes. Gold mining will continue to
produce elemental mercury and mercury(I) chloride byproducts and is expected to continue at
its current level (approximately 100 metric tons on an elemental mercury content basis) for the
next several years. Although some domestic mining operations may increase the amounts of
mercury they are capturing, some mines already capturing elemental mercury and producing
byproduct mercury compounds may close in the next ten years, and some mines may shift to
seams with lower mercury content (Lawrence, 2007).
3.3 Sources and Amounts of Mercury Compounds Exported
Table 3-13 presents the quantity and value of U.S. exports of
inorganic and organic mercury compounds in 2007 and
Export Ban Act
2008, as reported by the United States in the U.S. ITC
Dataweb or by U.S. trading partners in the United Nations
Comtrade database. The data were downloaded on
February 15, 2009. As with the data on imports, only
aggregated quantities of all mercury compounds are
available, and the two sources' estimates do not agree.
Crosswalk to Requirements in the Mercury
iii. Sources and amounts exported
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Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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October 14, 2009
U.S. Environmental Protection Agency
Table 3-13: Quantity and Value of U.S. Exports of Inorganic and Organic Mercury Compounds, by
Trade Database Source, 2007-2008
Country
Canada
China
Japan
Mexico
Taiwan
United Kingdom
Others
Total
Year
2007
2008
2007
2008
2007
2008
2007
2008
2007
2008
2007
2008
2007
2008
2007
2008
U.S. ITC
Metric Tons
7,626
275
5
42
3
2
104
20
less than 1
8
less than 1
5
85
28
7,823
380
Thousands of Dollars
$22,045
$1,158
$1,260
$1,721
$657
$722
$638
$28
$267
$584
$46
$152
$785
$1,269
$25,698
$5,634
Comtrade
(U.S. exports as reported as imports by
U.S. trading partners)
Metric Tons
1,932
a
a
a
a
a
a
a
a
a
a
a
613
a
2,545
a
Thousands of Dollars
$3,071
a
a
a
a
a
a
a
a
a
a
a
$3,835
a
$6,906
a
a. Data were not available for the given year and country.
Notes:
1) Data exclude HTS codes encompassing compounds other than mercury (specifically, HTS 3815902000, reaction
inhibitors, reaction accelerators and catalytic preparations, consisting wholly of inorganic substances; of mercury or
molybdenum).
2) Countries receiving exports only in either 2007 or 2008, but not both years, are included in the "others" category,
though individual countries in some cases received U.S. exports of significant size (e.g., Venezuela, 61 metric tons
in 2007; Turkey, 12 metric tons in 2008).
2008 data incomplete
According to the U.S. ITC, in 2007, 7,626 metric tons of mercury compounds were exported
from the United States to Canada and 104 metric tons to Mexico. Exports to all other countries
totaled 93 metric tons. In 2008, mercury compound exports totaled 275 metric tons to Canada,
42 metric tons to China, and only 20 metric tons to Mexico, and exports to all other countries
totaled 43 metric tons.
The large quantity of mercury compounds exported to Canada in 2007 raises the possibility that
a significant part of this total could be waste or byproduct materials being shipped to Canada
for disposal, or could otherwise represent a reporting anomaly. Canada reported a much
smaller import from the United States of 1,932 metric tons in its 2007 data provided to
Comtrade. In addition, U.S. ITC data indicate that the United States exported only 275 metric
tons of mercury compounds to Canada in 2008, a substantially lower amount than was reported
in 2007.
The source of the large quantity of mercury compounds exported to Canada in 2007 is unclear.
An export quantity of 7,626 metric tons is extremely large in the context of total global trade in
elemental mercury, which is estimated to be only 3,500 metric tons annually (UNEP, 2008). Due
Report to Congress
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
31
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October 14,2009 U.S. Environmental Protection Agency
to confidentiality concerns and data limitations, U.S. ITC could not provide information on why
the reported quantities of exported mercury compounds are several orders of magnitude larger
than what might be expected to satisfy global demand for mercury compounds. However, U.S.
ITC data do reveal a consistent pattern of exports of mercury compounds from the United
States to Canada during each month in 2007.
Given the UN estimate of global trade in elemental mercury of roughly 3,500 metric tons, if
7,626 metric tons of mercury-containing materials were, in fact, exported to Canada in 2007, it is
almost certain that these materials were not pure mercury compounds, and that the total
concentration of mercury compounds is in fact much lower than the total quantity reported.
However, mercury and mercury compound content is not specifically reported. One indication
that the compounds were of low purity, however, is the value of the shipments. The value for
these shipments (approximately $22 million) suggests a compound price of approximately $2.90
per kilogram. This is approximately an order of magnitude less expensive than mercury
compounds available for purchase on the global market, suggesting that these shipments were
materials with low mercury content or mercury compound-containing wastes.
The export of significant quantities of low-priced mercury compounds to Canada may indicate
that materials being shipped to Canada for disposal are being identified as mercury compounds
in trade documents, consistent with new, more general HTS codes for mercury compounds. The
closure of several U.S. chlor-alkali plants in recent years may have resulted in significant
quantities of mercury-containing waste that would previously have been reported under other
tariff codes.
Report to Congress 32
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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Crosswalk to Requirements in the Mercury
Export Ban Act
iv. Potential for processing into
elemental mercury
October 14,2009 U.S. Environmental Protection Agency
4. Potential for Export of Mercury Compounds To Be Used as a Source
for Elemental Mercury
4.1 Chemistry and Technological Feasibility of Conversion
Mercury is a Group IIB metal and is in the same group as zinc and
cadmium. Unlike the other members of this group, mercury has
two stable oxidation states: mercury(I)/ which takes the form of a
binary cation, (Hg2)2+/ and mercury(II) (Hg2+). Elemental mercury
(Hgฐ) can be oxidized to readily form compounds in either
oxidation state. Many of these mercury compounds, such as the
halide salts, oxides, and nitrates, undergo ligand exchange
reactions under mild conditions. Therefore, the common mercury
compounds can be readily interconverted. In addition, mercury is
one of the few metals that form stable, covalent bonds with
carbon. A variety of inorganic and organometallic mercury compounds can therefore be
generated in one or two synthetic steps from elemental mercury. Unique among metals,
elemental mercury is a liquid at room temperature and has a low boiling point (356.73ฐC) and
high vapor pressure (0.015 torr at 50ฐC). Mercury's high vapor pressure facilitates its removal
from mixtures by volatilization, and thermal decomposition of mercury compounds at elevated
temperatures often generates elemental mercury vapor, which can be condensed and collected
(Patnaik, 2003).
Mercury compounds that could be exported for the purpose of regenerating elemental mercury
must be readily available (or easily generated), stable, transportable, and easily converted to
elemental mercury. Compounds that do not meet these criteria would not be economically
competitive with existing sources of elemental mercury. Chemical processes ideally suited to
these criteria will utilize inexpensive, readily available reagents, and simple procedures and
equipment. Examples of the common chemical reactions that may be used to convert elemental
mercury to mercury compounds and are representative of those currently used or generated in
large-scale processes in the manufacturing, mining, power generation, and petroleum
industries, or in other commercial processes are provided in Appendix D. Also provided are
reactions than can be used to convert one mercury compound to another and processes that can
be used to decompose mercury compounds back into elemental mercury. Individual mercury
compound dossiers that include an examination of their potential for use as a source of
elemental mercury are presented in Appendix C. This section provides an overview of the
chemical processes involved in converting elemental mercury into mercury compounds, and
vice-versa, and evaluates the technical feasibility of exporting several mercury compounds.
4.1.1 Conversion of Elemental Mercury to Mercury Compounds
Elemental mercury can be easily converted in one or two steps to a variety of inorganic and
organometallic mercury compounds using inexpensive, readily available materials (Simon et
al., 2006; Patnaik, 2003; Nowak and Singer, 1995). Common conversion methods are explained
below.
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4.1.1.1 The Thermal Oxidation of Elemental Mercury into Mercury(II) Oxide
Elemental mercury is stable in dry air under ambient conditions and oxidizes slowly in the
presence of moisture. Direct oxidation of elemental mercury to mercury(II) oxide can be
accomplished at a synthetically useful rate by heating elemental mercury to a temperature of
350ฐC in air.
air
Hg + 1/2 02 ^ HgO
heat
4.1.1.2 The Chemical Conversion of Elemental Mercury into Mercury Halides
The reaction of elemental mercury with chlorine yields mercury chlorides. Unless an excess of
chlorine is used, the product obtained is a mixture of mercury(I) chloride and mercury(II)
chloride. The use of excess chlorine or the chlorination of mercury(I) chloride produces
mercury(II) chloride.
2Hg + C12 ^ Hg2Cl2
Hg2Cl2 + C12 ^ 2HgCl2
Analogous reactions with bromine and iodine yield the mercury bromides and iodides,
respectively.
4.1.1.3 The Chemical Conversion of Elemental Mercury in Waste Streams into Mercury
Halides
Mercury(I) chloride can, on heating, disproportionate to yield elemental mercury and
mercury(II) chloride. This reaction is exploited in scrubber systems for capturing elemental
mercury.
Hg2Cl2 *- ^ Hg + HgCl2
heat
When gases containing elemental mercury vapor are passed through an aqueous solution of
mercury(II) chloride, the above reaction is reversed, and insoluble mercury(I) chloride
precipitates out of solution and can be collected. This is the mercury conversion process used in
Nevada gold mining, known as the Boliden-Norzink process.
Hg + HgCl2 (soluble) ^ Hg2Cl2 (insoluble)
4.1.2 Conversion of Mercury Compounds to Other Mercury Compounds
The most practical synthesis of a particular mercury compound is often accomplished via the
conversion of one compound to another, even if a direct synthesis from elemental mercury is
possible. The soluble mercury(II) salts such as mercury(II) chloride, mercury(II) nitrate, and
mercury(II) acetate are frequently used in the commercial preparation of other mercury
compounds. For example, mercury(II) oxide is more economically produced by the reaction of
mercury(II) nitrate and an alkali hydroxide than by the rudimentary heating of elemental
mercury in air described earlier.
Hg(NO3)2 + 2NaOH * HgO + 2 NaNO3 + H2O
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This reaction sequence ultimately produces mercury(II) oxide in two steps from elemental
mercury using only nitric acid and sodium hydroxide as reagents.
4.1.3 Conversion of Mercury Compounds to Elemental Mercury
Mercury compounds can be readily converted to elemental mercury using techniques that
range from the simple to the complex. The three processes commonly used to accomplish this
transformation in order of increasing sophistication are thermal decomposition, chemical
reduction, and electrochemical reduction.
4.1.3.1 Thermal Decomposition
Many mercury compounds are decomposed and reduced upon heating to release elemental
mercury vapor. This process, also called retorting, is the simplest method for generating
elemental mercury from mercury compounds. In its most basic form, a retort consists of a
furnace and a suitable surface on which to condense the elemental mercury vapor for collection.
Commonly located at ore processing and waste processing facilities, the equipment can be
configured to accommodate the nature and volume of material processed. Modern operations
also include pollution control equipment such as dust collectors and scrubbers (DeVito and
Brooks, 2005).
4.1.3.2 Chemical Reduction
Another method for generating elemental mercury from mercury compounds is chemical
reduction. In a typical process, a mercury compound is dissolved or suspended in an aqueous
solution and treated with a reducing agent. The elemental mercury settles to the bottom of the
reactor as the reaction progresses and can be easily separated from the water. This process is
used extensively in some industrial applications, most notably the removal of elemental
mercury in chlor-alkali wastewater streams. Reducing agents that have been demonstrated to
generate elemental mercury in these waste streams include hydrazine, sodium hydride, and
sodium borohydride (Falbesaner et al., 1980; Nguyen, 1979; DeAngelis et al., 1978). The
reduction of mercury compounds with sodium borohydride under synthetic conditions is
known as the Ventron process (Nowak and Singer, 1995).
Some metals can reduce mercury compounds to elemental mercury. Barreau and Eusebe (1991)
report a method for preparing pure elemental mercury from mercury(I) chloride. Mercury(I)
chloride is suspended in an aqueous solution containing sulfuric acid (pH 0.5) and agitated with
a powdered reducing metal, typically iron. Other metals that have been reported to reduce
mercury chlorides include zinc, bismuth, tin, nickel, magnesium, manganese, and copper
(Gerow and Soule, 1974).
4.1.3.3 Electrochemical Reduction
The reduction of soluble mercury compounds can also be effected by means of electrochemical
reduction. In this process, the mercury compound is dissolved in an electrolyte solution,
electrodes made of suitable materials are inserted, and an electrical current is applied to the cell.
Elemental mercury initially forms as droplets at the cathode and subsequently either forms an
amalgam with the cathode metal or falls to the bottom of the cell, where it is collected. Large-
scale electrochemical cells are used in the plating industry, in metals extraction (electrowinning)
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in the mining industry, and in electrochemical waste treatment processes. Cell configuration,
electrolytes, anode and cathode compositions, and other conditions are optimized for each
process. Electrochemical reduction processes have the advantage that they can be performed on
both mercury(I) or (II) species. See Appendix D for illustrative examples of electrochemical
reduction processes.
4.1.4 Organomercury Compounds
Most organomercury compounds have limited use in commerce, are highly toxic, and are not
likely to be suitable for export. Organomercury(I) compounds are not stable and can be
prepared only at low temperatures. Although organomercury(II) compounds are relatively
stable to air and moisture, some of the reagents used to prepare them, such as
organomagnesium reagents (known as Grignard reagents), are moisture sensitive, and the
reactions must be carried out in dry solvents under an inert atmosphere, greatly complicating
these processes. Certain organomercury compounds have seen recent use as preservatives and
Pharmaceuticals (e.g., Thimerosal). Reactions used to prepare some representative
organomercury compounds are shown in Appendix D.
4.1.5 Candidate Compounds for Sources of Elemental Mercury Based on Technological
Feasibility of Conversion
Based on the technological conversion characteristics of mercury compounds described above
and the analysis of the individual chemicals presented in Appendix C and Appendix D, four
chemicals seem to be the most likely choices to be exported and converted to elemental mercury
abroad: mercury(I) chloride, mercury(II) oxide, mercury(II) nitrate, and mercury(II) sulfate.
These compounds have a high elemental mercury yield from conversion, and, given the
necessary equipment and technology, can be easily reduced to elemental mercury, and either
are readily available as a byproduct (mercury(I) chloride) or can be produced relatively easily
from surplus elemental mercury (see compounds with "High" potential for export as an
alternative to elemental mercury in Table 4-1).
Four other chemicals are potential candidates for export followed by regeneration of elemental
mercury based on technological feasibility of conversion: mercury(II) acetate, mercury(II)
chloride, mercury(II) iodide, and mercury(II) sulfide. These candidates generally cannot be
reduced to elemental mercury by heating and therefore are slightly more difficult to convert to
elemental mercury (see "Medium" compounds in Table 4-1).
Two additional chemicals could possibly be exported and reconverted to elemental mercury
abroad based on their technological feasibility of conversion; however, these chemicals require
manufacturing from other chemicals that are more likely to be exported and thus would require
an extra step, making them less likely to be chosen for export. These chemicals are
phenylmercury acetate and thimerosal (see "Low" compounds in Table 4-1).
Finally, the following two chemicals are not likely to be exported as a source of elemental
mercury due to low technological feasibility of conversion: mercury(II) selenide, and
mercury(II) thiocyanate. The chemistry of these compounds makes them difficult to prepare or
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handle, and unlikely to be exported with the purpose of regenerating the elemental mercury
abroad (see "Very Low" compounds in Table 4-1).
Greater detail on the characteristics of the individual mercury compounds that influence the
feasibility of their export and conversion can be found in Appendix C.
Table 4-1: Candidate Compounds, Sources, Feasibility of Conversion, and Potential for Export Based
on Technological Feasibility
Compound
Mercury (I)
chloride
Mercury (II)
oxide
Mercury (II)
sulfate
Mercury (II)
nitrate
Mercury (II)
acetate
Mercury (II)
chloride
Mercury (II)
iodide
Potential Sources
Product; Byproduct;
Waste; Convert from
surplus elemental
mercury
Product; Convert
from other common
mercury compounds;
Convert from surplus
elemental mercury
Product; Convert
from surplus
elemental mercury;
Byproduct
Product; Convert
from surplus
elemental mercury
Product
Product; Convert
from surplus
elemental mercury;
Convert from other
common mercury
compounds
Product; Convert
from surplus
elemental mercury;
Convert from other
common mercury
compounds
Processes That Would
Be Used To Convert
to Elemental Mercury
Outside U.S.
Chemical or
electrochemical
reduction; Dissociation
by light or heat
Decomposition by light
or heat; Electrolytic
reduction
Reduction by heating
Reduction by heating
Decomposition by heat
or light
Chemical or
electrochemical
reduction; Conversion
to other inorganic
compounds by heating
Conversion to other
inorganic compounds
by heating
Quantity of
Elemental
Mercury
Yield (%
Mercury by
Weight)
85%
93%
68%
62%
63%
74%
44%
Technological
Feasibility of
Producing for
Export and
Subsequent
Processing into
Elemental
Mercury
High
High
High
High
Medium
Medium
Medium
Rationale for
Determining
Potential
High elemental
mercury yield
from conversion;
easily reduced to
elemental
mercury; either
readily available
as a byproduct or
produced easily
from surplus
elemental
mercury
Generally cannot
be reduced to
elemental
mercury by
heating and
therefore are
slightly more
difficult to
convert to
elemental
mercury
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Table 4-1: Candidate Compounds, Sources, Feasibility of Conversion, and Potential for Export Based
on Technological Feasibility
Compound
Mercury (II)
sulfide
Phenyl
mercury (II)
acetate
Thimerosal
Mercury (II)
selenide
Mercury (II)
thiocyanate
Potential Sources
Naturally occurring;
Product; Convert
from surplus
elemental mercury;
Byproduct; Convert
from other common
mercury compounds
Product; Convert
from other common
mercury compounds
Product; Convert
from other common
mercury compounds
Waste; Convert from
surplus elemental
mercury
Product; Convert
from other common
mercury compounds
Processes That Would
Be Used To Convert
to Elemental Mercury
Outside U.S.
Reduction by retorting
Ventron process
(convert to inorganic
mercury compounds,
reduce with sodium
borohydride); Burning
Ventron process
(convert to inorganic
mercury compounds,
reduce with sodium
borohydride); Burning
Reduction by retorting
Decomposition by
heating (exothermic,
difficult to control)
Quantity of
Elemental
Mercury
Yield (%
Mercury by
Weight)
86%
60%
50%
72%
63%
Technological
Feasibility of
Producing for
Export and
Subsequent
Processing into
Elemental
Mercury
Medium
Low
Low
Very Low
Very Low
Rationale for
Determining
Potential
Require
manufacturing
from other
chemicals that are
more likely to be
exported and thus
would require an
extra step,
making them less
likely to be
chosen for export.
a Categories are defined as follows:
> High: Most likely candidates to be used for export and conversion to elemental mercury
> Medium: Potential candidates to be used for export and conversion to elemental mercury
> Low: Possible candidates, but too expensive because manufactured from other candidates that are more likely to be exported
> Very Low: Unlikely candidates because their chemistry makes them too difficult or expensive to prepare or handle
4.2 Economic Feasibility of Exporting Mercury Compounds to Regenerate
Elemental Mercury
In addition to being technologically feasible, it must be economically feasible to trade
compounds as a substitute supply for elemental mercury in order for markets to develop and
function. Economic feasibility requires not only that manufacture of mercury compounds and
regeneration of elemental mercury from those compounds be technically practical, but also that
this process be cost-competitive with other global supplies of elemental mercury. Note that this
section focuses on the economic feasibility of production and trade of mercury compounds as a
source of elemental mercury, rather than for use as compounds. Data in Chapter 3 suggest that
demand for mercury compounds is unlikely to increase enough to justify significant increases in
production or trade. EPA considered the economic feasibility of two different types of
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compound production: direct regeneration and sale of compounds from byproduct and waste,
and explicit manufacture of compounds using surplus elemental mercury.
The economic feasibility of using U.S.-developed mercury compounds as an alternative supply
of elemental mercury depends on the following factors:
> The costs of obtaining domestic supplies of elemental mercury or mercury compounds,
converting the elemental mercury into compounds (if necessary), shipping and handling
the compounds, and regenerating the elemental mercury after export must be lower
than the cost of providing elemental mercury from non-U.S. sources;
> The quantity of the compound manufactured in the United States (or available in
byproducts or wastes) must be sufficient to justify development of systems for
regenerating elemental mercury in other countries;
> Industrial capacity and technology for large-scale compound production in the United
States must either exist currently or be cost-effective to produce; and
> Sustained global demand for elemental mercury at a price high enough to offset the cost
of producing the compound and regenerating the elemental mercury must be likely to
justify any capital expenses needed to increase U.S. production.
The above factors illustrate that substantially increasing export of mercury compounds for
regeneration of elemental mercury would involve business risk for both suppliers of mercury
compounds and the importers who would regenerate the elemental mercury.
4.2.1 Overview of Options for Mercury Compound Export
Compounds may be exported under one of three scenarios: as value-added manufactured
products, as byproducts or recovered from wastes, and as high-volume compounds
manufactured from elemental mercury and exported for the purpose of regenerating the
elemental mercury outside the United States The economic viability of each of these export
scenarios depends on whether it is cost-competitive with other options, including the market
costs of competing products (e.g., other sources of compounds or elemental mercury) and the
domestic cost of disposal or long-term storage. Figure 4-1, Figure 4-2, and Figure 4-3 illustrate
the market dynamics for each export scenario.
| Figure 4-1: Mercury Compound Products
In the U. S.
Outside the U. S.
(Future expansion
of existing \
production capacity)
Hg Compound
Product
Export ^>
Hg Compound
Product
/- -^
Conversion ^> ( Elemental Hg j
V S
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U.S. producers currently develop only small quantities of compounds as products, using less
than two metric tons of elemental mercury, according to data reported to IMERC (NEWMOA,
2008). Production of these high-value specialty products in large-volumes would therefore
require additional capacity, and it is possible that significant new production of these
compounds would oversupply the market.
| Figure 4-2: Mercury Compounds in Waste or as Byproduct
In the U.S.
Outside the U.S.
Elemental Hg
stored in the U.S.
Export
In considering export of mercury compounds in waste or byproducts, the cost of
treatment/long-term storage/disposal of the recovered elemental mercury must be weighed
against the costs of export.16 Exported byproducts or waste streams can either be landfilled or
converted to elemental mercury for sale abroad. Most mercury compound-containing waste
streams have low enough concentrations of mercury that disposal abroad may be more cost
effective than conversion abroad, even if global elemental mercury prices rise. However, for
some mercury compound byproducts or wastes, the cost of export and conversion to elemental
mercury may be lower than the cost of retorting and storage in the United States. Currently,
only mercury(I) chloride can be economically exported as a cost-competitive source of elemental
mercury.
| Figure 4-3: Conversion of Elemental Mercury for Export as Mercury Compounds
In the U.S.
Outside the U. S.
f Elemental Hg J Conversion
The final export scenario for mercury compounds is production of compounds from elemental
mercury within the United States into compounds for export and regeneration of elemental
mercury. While this scenario is not currently cost-competitive with other supplies of elemental
mercury, in the context of an export ban, it is possible that U.S. producers could develop and
export compounds from elemental mercury as a cost-competitive alternative to long-term
16 For this analysis, EPA considered only the byproduct and waste containing more than de minimis amounts of
mercury.
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storage domestically, and as a competitive source of elemental mercury globally. To be viable,
however, this scenario requires that both storage prices and elemental mercury market prices be
high enough to offset any capital costs required with building additional compound production
capacity.
4.2.2 Key Market Dynamics and Features Affecting Compound Manufacture
In a market without trade constraints, manufactured mercury compounds are not a competitive
source of elemental mercury because they require elemental mercury as a raw material and
involve additional production costs. Byproduct compounds such as mercury(I) chloride may be
competitive if processing costs to regenerate elemental mercury from compounds are
competitive with costs of elemental mercury production from other sources (e.g., mined
mercury ore, recycling).
Enactment of a ban on the export of elemental mercury, however, creates both a barrier and a
potential opportunity for U.S. compound producers. Under the export ban, owners of elemental
mercury supplies in excess of domestic elemental mercury demand must bear the costs of long-
term storage. As a result, a significant portion of the domestic supply of elemental mercury will
have a negative value equal to the cost of long-term storage in the domestic market but a positive
value in the global market. A mercury compound producer who can first charge a "supplier"
(e.g., a gold mine) a fee for recycling surplus mercury, then use that mercury as a raw material
to produce a mercury compound, and finally sell that compound internationally, could
theoretically operate profitably if:
Market value of elemental mercury + avoided storage/treatment/disposal costs- (compound production
cost + export costs + mercury regeneration cost) > 0
The limited supply of U.S. domestic mercury, however, limits the financial opportunities
associated with this compound trade. A domestic U.S. compound producer would have two
supply sources for raw materials: compounds directly produced (as byproducts or in waste),
and elemental mercury otherwise slated for domestic storage (and, ultimately, treatment and
disposal) that can be used to manufacture compounds. The supply of surplus elemental
mercury and compounds coming to market is expected to be very small, with current domestic
surplus of elemental mercury estimated at roughly 80 to 100 metric tons per year and the
mercury content of byproduct compounds not likely to exceed 25 metric tons, annually.
Although a compound producer could obtain revenues both by charging the producer for
unwanted mercury (up to the cost of long-term storage/treatment/disposal) and by selling the
mercury compounds (at a price competitive with elemental mercury when regeneration costs
are considered), the total revenue associated with compounds manufactured from 125 metric
tons of surplus domestic elemental mercury or surplus mercury compounds is limited.
If a producer of compounds does not require any capital investment to begin operations, then it
may be possible to earn a profit by producing compounds that can compete as raw materials for
elemental mercury. However, the limited potential for revenue from the sale of elemental
mercury (due to the small quantity available in the United States) in turn limits the ability of a
producer to make significant capital investments in capacity or technology to expand mercury
compound production, particularly if operating costs associated with manufacturing a
compound are also high (e.g., due to waste management requirements).
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Given these constraints, manufacturers considering trade in compounds as a source for
elemental mercury must consider the prices and supply and demand trends in the global
elemental mercury market, as well as the direct costs associated with their operations, and
competition from domestic storage/treatment/disposal alternatives.
4.2.3 General Economic Considerations: Current Prices of Elemental Mercury and
Compounds
To ensure the economic feasibility of using compounds as an alternative source of elemental
mercury, producers must be able to rely on consistent elemental mercury prices. Current spot
prices (i.e., prices for immediate payment and delivery) for elemental mercury and mercury
compounds provide an initial insight into the economic feasibility of trading mercury
compounds as a substitute for elemental mercury.
Spot prices for elemental mercury appear to have remained in the range of $500-$700 per 76
pound (34.5 kilogram) flask since 2007 after decades of decline in prices coincident with a
declining market for elemental mercury (see Figure 4-4). Historical elemental mercury prices
were in the $2,000 per flask range in the 1940s (inflation-adjusted; 2008$, as are all price values
in this paragraph), averaged $658 per flask in the post-war period until 1950 and $1,419 per
flask from 1951 through 1964; and hit a peak price of $3,100 per flask in 1965 (USGS, 1998).
Since the late 1960s, prices began to decline steadily to less than $200 per flask in 2003; though
the price of elemental mercury briefly spiked to just over $1,000 per flask (approximately equal
to $29,000 per metric ton) in 2005 in the face of perceived shortfalls due to a decline in primary
mercury mining and strong elemental mercury demand due to the rising price of gold (USGS,
1998; Metal Bulletin, 2005). Prices declined from this brief relative price peak in 2005 within
months, and as of 2008, the price for a flask of the metal had stabilized at approximately $600.
This price is considered fairly strong compared with prices in the 1990s (elemental mercury
averaged $230 per flask from 1991 through 2003), but has not shown any significant increase
since the passage of MEBA (USGS, 2009). Price fluctuations of the type seen in the last 10 years
can be expected to occur in small and declining markets such as the elemental mercury market
because small changes in production (e.g., the retirement of a single chlor-alkali plant or a
temporary mine closure) can have a significant short-term impact on total supply.
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Figure 4-4: Historical Prices for Elemental Mercury: 1929 - 2009
$3,500
$3,000
-Nominal Price
-Inflation-adjusted Price
(2008$)
>
Year
Available information for mercury compounds sold as products reveals a wide range of prices.
Bulk mercury compounds produced as byproducts from industrial processes or mining (e.g.,
mercury(I) chloride (calomel)) likely command minimal prices, and in some cases processors
may charge a fee for acceptance of the byproducts. In contrast, mercury compounds produced
for industrial or laboratory use range in price depending on whether or not they are purchased
in bulk. This two-tiered cost structure exists for elemental mercury as well: bulk elemental
mercury typically trades for hundreds of dollars per 76-pound flask (34.5 kilograms), but is sold
by laboratory chemical providers in small quantities of similar quality at an average price of
roughly $200 per pound ($440.92 per kilogram), a 3,000 percent mark-up.
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Table 4-2: Market Prices of Elemental Mercury and Selected Mercury Compounds
Compound
Mercury(I) chloride (specialty
chemical)
Mercury(I) chloride (byproduct)
Mercury(II) chloride
Mercury (II) nitrate
Mercury(II) sulfate
Mercury (II) sulfate (waste)
Elemental mercury
Specialty
Chemical
Price
(per
Kilogram)
$236
NA
$295
$699
$1473
NA
$432
Bulk Chemical
Price
(per Kilogram,
including
shipping)
Unknown
Low
$27
$32
$31
Low
$17.42
Ratio of
Specialty
Chemical
to Bulk
Price
NA
NA
11
22
48
NA
25
Percent
Mercury
Content
85%
<85%
74%
62%
68%
<68%
100%
Price per Kilogram
of Mercury (bulk)
(does not include
processing)
Likely equal to or
higher than
elemental mercury
Likely low
$36.49
$51.61
$45.59
Likely low
$17.42
Sources: Fisher Scientific, 2009; Gin-jar Chemicals, 2009
Bulk mercury compounds are produced and sold globally. Online retail price estimates for bulk
compounds (minimum order of 500 kilograms) are in the $27 to $32 range including the base
cost, insurance, and shipping (Gurjar Chemicals, 2009). As Table 4-2 illustrates, bulk mercury
compound prices are higher than the price of elemental mercury, consistent with the value-
added nature of manufactured mercury compounds, which typically use elemental mercury as
an input.17
EPA initially considered the possibility that manufactured high-volume compounds could be
sold into the market for compounds (i.e., for use as compounds, rather than for recovering
elemental mercury), but data on quantities of compounds produced and sold in the United
States suggest that the quantities of compounds necessary to ensure operational profitability
would far exceed existing demand for specific compounds, even those sold in bulk. As a result,
producers of high-volume compounds would most likely be unable to sell those compounds at
current market prices.
4.2.4 U.S. Production Capacity for High-Volume, Low-Cost Compound Production
U.S. manufacturers currently produce mercury compounds for high-value manufacturing uses,
but these firms have little economic incentive to expand this production significantly and risk
oversupply in small markets, though they may take advantage of reduced U.S. elemental
mercury prices resulting from an export ban and increase production incrementally.
Data from IMERC on 2004 U.S. sales of mercury compounds identify roughly 30 companies
reporting production of chemical compounds containing mercury. The total quantity of
mercury used in these compounds, which include the compounds considered for this report as
well as some industrial fixatives and other mixtures, is less than two metric tons for 2004.18 The
17 According to the United Nations Environment Programme, retorting costs from wastes with greater than 10
percent mercury content are "less than $50 per kg," and mercury recovery from mercury(I) chloride costs
approximately $10 to $20 per kg (UNEP, 2008).
18 NEWMOA 2008, supplemented with personal communication with Adam Wienert, April 9, 2009. Mr. Wienert
noted that the July 2008 NEWMOA report predated receipt of submissions from roughly 10 companies, and therefore
the roughly one metric ton of mercury reported in that document is a low estimate.
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trend since 2001 appears to be one of slowly declining production, consistent with general
trends in the use of mercury in manufacturing applications globally.
While the IMERC chemical compound quantity estimates include only manufacturers required
to report to IMERQ the data suggest that U.S. industrial production of mercury compounds is
highly specialized, and is probably not adequate for immediate high-volume production of
compounds using many metric tons of elemental mercury. Therefore, U.S. mercury compound
producers are not likely to be an immediate source of supply for significant new trade in
mercury compounds for the purpose of retorting elemental mercury.
The only compounds that may see significant growth in production in the current market are
those such as mercury(I) chloride that occur as byproducts or in waste. Generation of these
compounds is driven by external factors such as gold prices and adoption of air pollution
control processes and is disconnected from market demand for compounds as products. In
contrast to mercury compound manufacturers, U.S. mercury waste management companies are
well positioned to process large volumes of byproduct or waste compounds, either to
regenerate elemental mercury or to refine the compounds to an industrial grade. To date, U.S.
mercury recyclers have emphasized regeneration of elemental mercury from compounds or, in
the case of mercury(II) sulfide, development of compounds in order to accomplish mercury
disposal abroad (Bethlehem Apparatus, 2009). It is possible that companies in this sector could
leverage and expand their existing elemental mercury purification capacity and technology to
economically refine or develop compounds for trade as an alternative to storage domestically or
disposal abroad, but only if they perceive sufficient market demand to justify the adoption of
new technologies, processes, and permits. As a result, the feasibility of compounds as an
alternative supply of elemental mercury requires consideration of strength of demand for
elemental mercury, and the ability of current non-U.S. elemental mercury supplies to meet that
demand at competitive prices.
4.2.5 Supply and Demand Information for Elemental Mercury
Elemental mercury is traded in a very small market characterized by well-established
relationships among a limited number of traders and industrial customers. Recent estimates of
the size of the global elemental mercury market estimate global demand for elemental mercury
at roughly 3,500 metric tons annually (UNEP, 2008). However, this estimate reflects significant
uncertainty regarding two key sources of demand: Chinese manufacturing and artisanal gold
mining operations. The Chinese government estimates elemental mercury use in China at
roughly 1,100 metric tons per year (China Chemicals Registration Center, 2005). Artisanal gold
mining operations may account for up to 22 percent of the global demand for elemental
mercury (UNEP, 2008). A key concern for policy makers is the extent to which demand in China
and in artisanal gold mining areas may seek alternative sources of elemental mercury by
processing compounds if the global elemental mercury supply decreases due to export bans.
4.2.5.1 Global Elemental Mercury Market
Consistent with trends observed over recent decades, global demand for mercury in products
and manufacturing (e.g., paint, batteries) is expected to continue to decline in coming years in
Report to Congress 45
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most sectors, with the exception of lighting. The quantities of mercury used as an agent,
cathode, or catalyst in certain sectors such as in the production of vinyl chloride monomer and
polyurethane in China is not well documented, and it is therefore difficult to predict future
trends in demand for those uses.19
In recent years as the price of gold has increased, demand for elemental mercury by artisanal
gold miners appears to have increased, though the total quantities used by artisanal miners are
very difficult to estimate. Artisanal gold mining operations are generally illegal which adds to
the difficulty estimating how much is used. Elemental mercury is typically supplied to these
operations indirectly and in small quantities, often through black markets. The United Nations
Environment Programme (UNEP) has estimated that artisanal gold miners use more than 600
and perhaps as much as 1,000 metric tons of elemental mercury annually (Maxson, 2006). This
remains a rough estimate due to the difficulties in acquiring information.
Global supply of elemental mercury to meet industrial and artisanal mining demand includes
primary mining for mercury in China and Kyrgyzstan, production of by-product mercury from
other metals mines, and regeneration of secondary elemental mercury from industrial processes
such as chlor-alkali facilities, and from waste. Primary elemental mercury production has
decreased consistently in recent decades. Global primary mercury mining in recent decades has
been dominated by three nations mining mercury for export (Spain, Kyrgyzstan and Algeria),
and China, which has mostly provided for its own robust home market. Both Spain and Algeria
have stopped mercury mining operations (Maxson, 2006). During the early to mid-2000s, China
restricted mercury imports and increased domestic production of elemental mercury, as it
determined that it could once again produce elemental mercury at its mines for less than it
would cost to import the elemental mercury from elsewhere. China has a substantial internal
market for elemental mercury, has not historically exported much elemental mercury, and is not
expected to start now (Maxson, 2006). Kyrgyzstan has been producing close to its practical
capacity of 600 metric tons of elemental mercury per year (Maxson, 2006). In 1990, global
supply was approximately 7,000 metric tons; in 2005 it was estimated to be about 3,500 metric
tons (Maxson, 2006). The government of Kyrgyzstan is working on a joint project with
Switzerland and the UN to assess ways to phase out mercury mining in Kyrgyzstan.
Overall, the trend in primary mercury mining over recent years has been a significant decrease
in production. The only large-scale primary mercury mine currently feeding global supply is in
Kyrgyzstan and is a state-run facility that may not react predictably to future market trends.
While increased market prices could create an incentive for additional mines to enter the
market, the costs and time associated with preparing those mines for production might be
prohibitive. Further, other factors such as the pledge by the International Council on Mining
and Metals not to open new primary mercury mines decreases the likelihood that new mining
will occur.
19 Although data for China are uncertain, one estimate of demand for mercury for use in vinyl chloride monomer
was approximately 550 metric tons annually in 2004, with an estimated increase to 900 metric tons by 2010 (NRDC,
2007).
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Secondary sources of elemental mercury such as old mine tailings may also begin to provide
elemental mercury to market if prices increase; for example, the Commission for Environmental
Cooperation estimates that tailings from silver mines in the Zacatecas region of Mexico contain
approximately 13,000 metric tons of mercury reserves (Mexican Mercury Market Report, 2008).
Byproduct mercury production from mines (such as gold) is likely to remain relatively constant
at approximately 500 metric tons annually (UNEP, 2008).
Elemental mercury from chlor-alkali plants and from the recycling of mercury-containing
products also continues to enter the market. Chlor-alkali plants in regions unaffected by the EU
and U.S. export bans currently store approximately 11,000 metric tons of elemental mercury that
may be delivered to the global market over the next 40 years as these plants are retired, and
demand for elemental mercury from this sector will simultaneously decline.20 In the long term,
the quantity of elemental mercury coming to market from products will likely decrease
reflecting the decrease in mercury used in manufactured products, though mercury regenerated
from air pollution control systems is likely to continue and may increase. Note that additional
constraints on trade of secondary mercury (e.g., chlor-alkali mercury) through treaty or
legislation in other countries could result in reductions in elemental mercury supply (and
potentially higher elemental mercury prices) for some time, but it is not possible to assess the
specific market impacts of supply constraints because other sources of supply (e.g., regeneration
of elemental mercury from historic mine tailings) may increase to meet demand.
As the regeneration of elemental mercury from chlor-alkali plants and from products continues
and demand declines in the next several decades, it is possible that a state of occasional or even
chronic global oversupply of elemental mercury could occur, even if the market in the near term
is characterized by periods of supply shortage. Moreover, efforts to reduce mercury content in
products may also reduce demand for certain mercury compounds. For example, as mercury
use in batteries continues to be reduced, demand for mercury(II) oxide, a compound of mercury
used in battery manufacturing, may also decrease. Although supply of elemental mercury is
difficult to predict with accuracy, it is likely that elemental mercury will continue to be available
to meet global demand, even when export bans in the European Union and United States take
effect. As a result, it is difficult to envision a market in which scarcity of elemental mercury
results in sustained market prices for elemental mercury that are much higher than they are
currently.
Potential Impact of Mercury Global Treaty
According to Decision 25/5 "Chemicals management, including mercury" of the 25th session of
the United Nations Environment Programme Governing Council / Global Ministerial
Environmental Forum held in February of 2009 in Nairobi, Kenya, members agreed to "further
international action consisting of the elaboration of a legally binding instrument on mercury,
20 This estimate assumes that approximately 8,000 of the 9,000 metric tons of mercury still held in European mercury
cells and approximately 1,000 tons of mercury held in U.S. mercury cells will be diverted to storage as a result of the
bans (Eurochlor, 2008; Chlorine Institute, 2008).This estimate also is based on the assumption that each of the four
remaining mercury cell chlor-alkali facilities in the United States that are anticipated to continue to operate after 2013
contains 250 metric tons of elemental mercury.
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which could include both binding and voluntary approaches, together with interim activities, to
reduce risks to human health and the environment" (UNEP 2009). A future treaty may result in
decreased global demand, supply, and trade in elemental mercury, which would in turn affect
the incentives for exporting mercury compounds from the United States for processing into
elemental mercury for the international market. Such potential changes are uncertain at this
time.
Potential Impact of Mercury Export Ban Act
The possibility exists that the decrease in global supply of mercury due to the U.S. ban on
elemental mercury could have unintended effects that work against the goal of the act, which is
to reduce release of mercury to the environment. One of these unintended effects, although
unlikely, could be to increase primary mercury mining in other countries. However, based on
the long-term trend of decreasing primary mining, the cost of opening a new mine, and the
commitment of the members of the International Council on Mining and Metals not to produce
mercury as a primary product, it is unlikely that any new mines will open.21 Another potential
impact could theoretically be a reduction in voluntary mercury recycling in the United States,
including recovery of mercury from consumer products. At this time, EPA has no evidence that
negative effects of the export ban are likely. However, if they occur, expansion of the ban to
mercury compounds could add to the effects because of the further decrease in U.S.
contribution to global supply.
4.2.5.2 U.S. Elemental Mercury Market
The U.S. domestic elemental mercury market represents a limited and decreasing portion of the
global elemental mercury market. U.S. domestic demand for elemental mercury for industrial
use continues to decline, and is currently estimated to be approximately 100 metric tons - less
than 5 percent of the global market (Balistreri, 2007; Chlorine Institute, 2008). Total U.S.
domestic supply has been in the range of 180-200 metric tons from U.S. gold mines and waste,
product regeneration, and the frequent closure of mercury-cell chlor-alkali plants over the past
decade (Balistreri, 2007). In recent years U.S. domestic production of secondary elemental
mercury has been sufficient to meet domestic demand, and supply an additional 80-100 metric
tons per year to the global market (Lawrence, 2007). Domestic demand for mercury is likely to
decline as manufacturing shifts away from mercury-containing products and chlor-alkali plants
continue to close, and the reduced use of mercury-containing products will likely result in a
long-term decline in secondary mercury recovery from products (Lawrence, 2007). Other
sources of secondary and byproduct mercury, such as gold mining and regeneration of
elemental mercury from air pollution equipment, are likely to continue and may increase,
particularly if gold prices remain strong and mining expands to lower-quality seams. These
sources, however, are also driven in part by air emissions control requirements, advances in
technology, and mercury content in mine reserves.
Independent of U.S. domestic production and regeneration of elemental mercury, U.S. waste
recovery operations and brokers have imported and exported several hundred metric tons of
21 See www.icmm.com
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elemental mercury per year. Currently, trade in elemental mercury and trade in compounds is
primarily limited to the import of significant quantities of mercury(I) chloride, probably for the
purpose of extracting and selling elemental mercury. In the context of MEBA, operations to
regenerate elemental mercury from mercury(I) chloride are likely to move outside of the United
States and continue.
4.2.5.3 Implications of Global Mercury Market for Compound Trade
Recent trends in elemental mercury trade do not suggest that a significant, long-term shortage
of elemental mercury will emerge in the near future, absent significant new agreements to
further restrict supply. Recent market trends include decline in industrial use, consistent or
potentially growing secondary production, and relatively stable prices for several years. Price
swings are likely in the future as the market contracts, and prices could potentially rise for a
time following the implementation of the EU export ban in 2011. In the long term, however,
elemental mercury prices are likely to be moderated by increases in secondary supplies such as
chlor-alkali plant retirements outside of the European Union and, possibly, by release of private
stockpiles of elemental mercury held by recyclers and traders. It is unlikely that an elemental
mercury shortage or price shock would be severe or persistent enough to encourage demand for
compounds as an alternative source of elemental mercury, particularly because compound
prices would also be affected by any severe elemental mercury shortage.
These price and demand trends limit the potential for significant demand for compounds as a
source of elemental mercury. However, in limited circumstances it is possible that trade in
compounds as sources of elemental mercury could be feasible if domestic long-term
storage/treatment/disposal costs, as well as foreign disposal costs, are relatively high and
generators seek a less costly option than regeneration and storage of elemental mercury. Due to
the large size of the companies that produce mercury compounds, the total costs associated
with long-term storage and disposal of mercury may not be a significant factor in their
management decisions. In some cases, these companies may choose disposal or storage in spite
of higher costs, if, for example, they are concerned about long-term liability or adverse publicity
associated with future uses of mercury from their facilities.
4.2.6 Consideration of Specific Compounds with Potential to Supply Elemental Mercury
As presented in Sections 3.1.3 and 3.1.4, five compounds are currently generated as byproducts
or in waste from industrial processes: mercury(I) chloride, mercury(II) oxide, mercury(II)
sulfide, mercury(II) sulfate, and mercury(II) selenide. Of these five, only mercury(I) chloride is
generated in a significant quantity. Generators of these byproduct or waste compounds, along
with generators of excess elemental mercury and some mercury compound-containing wastes,
have an incentive to weigh the costs of disposition path alternatives.
Of these, the largest quantity is mercury(I) chloride that is produced annually by domestic gold
mines; primarily in Nevada (see Table 3-11). Quantities of mercury(II) sulfate, mercury (II)
sulfide, and mercury(II) selenide waste are more difficult to estimate, as discussed in Section
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3.1.3 and Section 3.1.4. Total quantities produced, however, are likely to be significantly smaller
than quantities of mercury(I) chloride produced (Bethlehem Apparatus, 2009; EPA, 2007a).22
Management options for these compounds, and for surplus elemental mercury, include:
> Retorting and long-term storage of elemental mercury
> Other options for disposal (if available)
> Processing and sale (including export) of compounds.
A handful of U.S. mercury waste recovery companies (i.e., retorters), including Bethlehem
Apparatus, Mercury Waste Solutions, and D.F. Goldsmith, have the capacity and technology to
perform high-volume waste recovery for these compounds. These firms also have relationships
with generators of byproduct mercury, mercury wastes and mercury compounds, and with
purchasers of elemental mercury.
Mercury recyclers may have an economic incentive to expand operations to produce high-
volume mercury compounds if they perceive adequate demand and determine that they are
cost-competitive. As one example, mercury(II) oxide is currently produced as an interim
product in processing mercury(I) chloride. Depending on the type of process used it could be
possible to produce mercury(II) oxide in bulk by adjusting processes already in place.
Production of compounds such as mercury(II) sulfate and mercury(II) nitrate, though also
relatively simple, would require significant capital investment to add new production lines and
obtain permitting to handle mercury-containing wastes and other hazardous materials (e.g.,
sulfuric acid). Given the small quantities of available domestic elemental mercury supplies and
the difficulty predicting sustained high elemental mercury prices, it is not clear that these
companies would assume this business risk.
In addition, it appears that at least one company (Bethlehem Apparatus) is pursuing disposal
technologies rather than emphasizing opportunities to export compounds for elemental
mercury recovery. It is possible that this disposal solution may represent a low-cost alternative
to long-term elemental mercury storage that is also a relatively low-risk manufacturing venture
for the recycler.
4.2.7 Capacity Outside of the United States To Convert Compounds to Elemental Mercury
In addition to manufacturing or recovering compounds, a producer must ensure that capacity
exists outside the United States for recovery of elemental mercury. At this time, it appears that
only byproduct compounds (e.g., mercury(I) chloride and mercury(II) sulfide) are currently
traded as sources of elemental mercury. EPA was unable to find any evidence that any
compounds are currently exported from the United States for processing into elemental
mercury in other countries.
In the event that global supply of elemental mercury is severely constrained, increased demand
for compounds as alternative sources of elemental mercury would focus on compounds that can
be easily treated to regenerate elemental mercury. As noted in Section 4.1, several compounds
22 Mercury (II) sulfate is typically produced by smelters.
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(e.g., mercury(I) chloride, mercury(II) oxide, mercury(II) sulfate, or mercury(II) nitrate) can
provide elemental mercury through simple roasting and condensing. Regeneration of
elemental mercury from many other mercury compounds requires chemical conversion
(reduction of mercury to elemental mercury).
The technology to recover elemental mercury from mercury(II) oxide, mercury(II)sulfate, and
mercury(II) nitrate is widely available globally. However, unless a U.S. producer operates its
own off-shore recovery facility, it may be difficult to ensure that demand would remain
constant. While the financial commitment associated with basic retorting technology is not
prohibitively expensive, a purchaser will invest in it only if he believes that recovery of
elemental mercury from compounds is, and will remain, less expensive than the direct purchase
of elemental mercury. The markets of most concern, such as artisanal mining, are in many ways
least likely to invest in capital equipment for processing mercury, given that their operations
require that elemental mercury be widely distributed in small quantities throughout remote
geographical areas.
Even if elemental mercury prices were to rise in the future, it is likely that (a) mercury
compound prices would also increase, and (b) mercury from byproduct from existing non-
mercury mines or from secondary sources such as historic mine tailings, would increase to
provide additional elemental mercury.23 Given this economic dynamic, it is difficult to identify
market conditions that would favor the development of significant demand for compounds as
alternative sources of elemental mercury.
4.3 Assessment of Potential for Export of Compounds Based on Technological and
Economic Factors
Table 4-3 shows the results of EPA's assessment of the potential for export of the compounds
studied in this report. The table is organized hierarchically to first show the most likely
candidates for potential export and conversion to elemental mercury. For their overall
assessment, EPA considered technical feasibility in conjunction with economic feasibility for
each compound for each source (i.e. specialty chemical manufacture, waste, byproduct). The
resultant characterizations are as follows:
Assessment Technical Feasibility Economic Feasibility
Likely High Currently produced in significant quantities
Low cost for conversion
23 It is difficult to obtain specific information about primary mercury mines, particularly in China, but recent formal
cutbacks (approximately a decade ago) in production appeared to be correlated with either low prices or significant
secondary supply (e.g., from chlor-alkali plant closures) (NRDC, 2007). Moreover, the China mining association web
site reports that Chinese mines have a capacity of over 900 tons with at least three large mines producing 100 tons per
year. A market with longer-term supply constraints and higher prices would provide the basis for expansion of these
operations. Furthermore, small scale mercury mining, along with recovery of mercury from historic mine tailings, is
already occurring in Mexico at current prices and may expand if prices increase (Mexican Mercury Market Report,
2008). Finally, larger-scale gold mines in areas with high mercury concentrations may improve recovery efforts if
these become more economical in a high-priced mercury market.
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Little if any new capital investment
Evidence of current international trade
Somewhat Likely High Low cost for conversion
Capital Investment needed to expand production
capacity
No current trade
Unlikely Medium to Low Significant cost for conversion
Very Unlikely Low Currently produced in limited quantities
High cost for conversion
An important factor in determining the economic feasibility of exporting a mercury compound
as a substitute for elemental mercury is whether trade in the compound would allow the
holders of mercury supplies to avoid storage/treatment/disposal costs. For compounds that are
currently available as byproducts or waste, the principal disposition path is recovery (retorting)
and long-term storage of elemental mercury. For some compound-bearing wastes with low
mercury content, other disposal options may be feasible, but Table 4-3 assumes that compounds
include high mercury content and must be retorted. For compounds produced from surplus
domestic elemental mercury supplies, disposition costs for elemental mercury would still be a
relevant consideration, though retort costs would be minimal.
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U.S. Environmental Protection Agency
Table 4-3: Summary of Technological Feasibility, Economic Feasibility, and Overall Potential for Export of Candidate Compounds
Compound
Mercury (I)
chloride
Mercury(II) oxide
Technological Feasibility of Conversion
Processes
Used to
Convert to
Elemental
Mercury
Chemical or
GiGctroc.ri.Gmi
cal reduction;
Dissociation
by light or
heat
Decompositi
on by light or
heat;
Electrolytic
reduction
Percent
Mercury
by
Weight
85%
93%
Potential for
Export Based
on Technical
Feasibility a
High
High
Economic Feasibility
Potential source
Mining and air
pollution control
byproduct
Convert surplus
elemental mercury to
bulk compound;
Increase specialty
chemical production;
Byproduct;
Convert surplus
elemental mercury to
bulk compound;
Convert from other
common mercury
compounds
Quantity
Reported by
Producers'3
^25 metric tons
of Hg/yearc
1.3kg
32.5 kg
Avoided
Retort and
Long-Term
Storage
Costs 6
Significant
Moderate
Moderate to
significant
Processing Costs for
Sale
Low technical
requirements;
Requires processing
to remove
impurities; offset by
significant retort and
long term storage
costs (retort + long-
term storage/
treatment/ disposal
costs)
Higher cost inputs
required; equal to
manufacturing costs.
Low technical
requirements; equal
to manufacturing
costs. Could be
produced in bulk as
an interim product
in mercury (I)
chloride processing.
Overall Potential
for Export
Likely (for
byproduct): large
volume currently
traded internationally
and imported by the
U.S. for regenerating
of elemental mercury.
Unlikely
Somewhat likely;
requires new capacity.
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Table 4-3: Summary of Technological Feasibility, Economic Feasibility, and Overall Potential for Export of Candidate Compounds
Compound
Mercury (II)
sulfate
Mercury (II)
nitrate
Technological Feasibility of Conversion
Processes
Used to
Convert to
Elemental
Mercury
Reduction by
heating
Reduction by
heating
Percent
Mercury
by
Weight
68%
62%
Potential for
Export Based
on Technical
Feasibility a
High
High
Economic Feasibility
Potential source
Waste from smelters:
Convert surplus
elemental mercury to
bulk compound;
Convert surplus
elemental mercury to
bulk compound;
Increase specialty
chemical production;
Convert surplus
elemental mercury to
bulk compound;
Increase specialty
r J
chemical production
Quantity
Reported by
Producers'3
Not Available
260.8 kg
88.7kg
Avoided
Retort and
Long-Term
Storage
Costs 6
Moderate to
significant
Moderate
Processing Costs for
Sale
Cost unclear:
requires purification;
Significant retort
and long term
storage costs (retort
+ long-term storage/
treatment/ disposal
costs)
Low technical
requirements; equal
to manufacturing
costs. Bulk
production would
require RCRA
Subtitle C Permitting
for disposal of
mercury-containing
wastes.
Low technical
requirements; equal
to manufacturing
costs. Bulk
production would
require RCRA
Subtitle C Permitting
for disposal of
mercury-containing
wastes.
Overall Potential
for Export
Somewhat likely (for
waste); requires new
capacity.
Unlikely
Somewhat Likely;
little existing capacity.
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U.S. Environmental Protection Agency
Table 4-3: Summary of Technological Feasibility, Economic Feasibility, and Overall Potential for Export of Candidate Compounds
Compound
Mercury (II)
acetate
Mercury (II)
chloride
Mercury (II)
iodide
Mercury (II)
sulfide
Technological Feasibility of Conversion
Processes
Used to
Convert to
Elemental
Mercury
Decompositi
on by heat or
light
Chemical or
electrochemi
cal reduction;
Conversion
to other
inorganic
compounds
to be
converted by
heating
Conversion
to other
inorganic
compounds
to be
converted by
heating
Reduction by
retorting
Percent
Mercury
by
Weight
63%
74%
44%
86%
Potential for
Export Based
on Technical
Feasibility a
Medium
Medium
Medium
]VIedium
Economic Feasibility
Potential source
Increase specialty
chemical production
Increase specialty
chemical production;;
Convert from
surplus elemental
mercury; Convert
from other common
mercury compounds
Increase specialty
chemical production;
Convert from surplus
elemental mercury;
Convert from other
common mercury
compounds
Increase specialty
chemical production;
Naturally occurring;
Convert from surplus
elemental mercury;
Byproduct; Convert
from other common
mercury compounds,
Quantity
Reported by
Producers'3
41.3 kg
76.8 kg
11.3kg
06kff
VJ.U JS.g
Avoided
Retort and
Long-Term
Storage
Costs 6
Not
applicable
Not
applicable
Not
applicable
Not
applicable
Processing Costs for
Sale
Equal to
manufacturing costs.
Equal to
manufacturing costs.
Equal to
manufacturing costs.
Equal to
manufacturing costs.
Overall Potential
for Export
Unlikely; requires new
capacity.
Unlikely; requires new
capacity.
Unlikely; requires new
capacity.
Somewhat
likely/ unlikely;
manufactured product
unlikely to be cost-
competitive with a
naturally occurring
source of mercury (II)
sulfide (cinnabar ore).
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Table 4-3: Summary of Technological Feasibility, Economic Feasibility, and Overall Potential for Export of Candidate Compounds
Compound
Phenyl
mercury (II)
acetate
Mercury (II)
selenide
Technological Feasibility of Conversion
Processes
Used to
Convert to
Elemental
Mercury
Ventron
process
(convert to
inorganic
mercury
compounds,
sodium
borohydride)
; Burning
Reduction by
retorting
Percent
Mercury
by
Weight
60%
72%
Potential for
Export Based
on Technical
Feasibility a
Low
Very Low
Economic Feasibility
Potential source
Waste
Naturally occurring
(Cinnabar)
Convert from other
common mercury
compounds;
Increase specialty
chemical production
Waste;
Convert from other
common mercury
compounds
Quantity
Reported by
Producers'3
Not Available,
but possibly
significant
No active mines
in the U S but
found in
abandoned Hg
mines
0.2kg
Small quantities
Avoided
Retort and
Long-Term
Storage
Costs 6
Significant;
and export
currently
disposal
optionc
Not
applicable
Not
applicable
Significant
avoided
retort and
long-term
storage /
treatment /
disposal costs
Processing Costs for
Sale
Low technical
requirements;
Requires processing
to remove
impurities.
Not applicable
Equal to
manufacturing costs.
Requires expensive
input material -
selenium; Significant
retort and long term
storage costs/
treatment/
disposal costs.
Overall Potential
for Export
Unlikely
Very Unlikely
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Table 4-3: Summary of Technological Feasibility, Economic Feasibility, and Overall Potential for Export of Candidate Compounds
Compound
Mercury (II)
thiocyanate
Thimerosal
Technological Feasibility of Conversion
Processes
Used to
Convert to
Elemental
Mercury
Decompositi
on by
heating
(exothermic,
difficult to
control)
Ventron
process
(convert to
inorganic
mercury
compounds,
reduce with
sodium
borohydride)
; Burning
Percent
Mercury
by
Weight
63%
50%
Potential for
Export Based
on Technical
Feasibility a
Very Low
Low
Notes:
a. Categories are defined as follows:
> High: Likely candidates to be used for export and conversion to elenis
> Medium: Potential candidates to be used for export and conversion tc
> Low: Possible candidates, but too expensive because manufactured fr
> Very Low: Unlikely candidates because their chemistry makes them t
b. Quantities of manufactured products from IMERC 2004 data unless o
c. Quantities of mercury(I) chloride are produced as mercury(I) chloride
representatives estimate that the current production of mercury(I) chl
by gold mines in the United States
d. Some mercury(II) sulfide is produced as a stabilized waste for landfil
e. NEWMOA "IMERC Mercury Added Products Database," accessed at
f. Long-term storage costs and overall disposition pathway costs for me
g. As currently manufactured, retort and long-term storage costs are not
the long-term storage/ treatment/ disposal fee would become relevan
Source: NEWMOA
Economic Feasibility
Potential source
Convert from other
common mercury
compounds;
Increase specialty
chemical production
Increase specialty
chemical production
Quantity
Reported by
Producers'3
6.4 kgf
unknown
Avoided
Retort and
Long-Term
Storage
Costs B
Not
applicable
Not
applicable
Processing Costs for
Sale
Equal to
manufacturing costs.
High-cost inputs and
process; Equal to
manufacturing costs.
Overall Potential
for Export
Very Unlikely
Very Unlikely
?ntal mercury
elemental mercury
om other candidates that are more likely to be exported
30 difficult or expensive to prepare or handle
therwise noted.
waste by domestic gold mines; primarily in Nevada Qones and Miller, 2005; see Table IV-5, above). Barrick
oride at the Goldstrike mine is roughly 25 metric tons, and represents the majority of mercury(I) chloride produced
ing. (Bethlehem Apparatus, 2009).
: http://www.newmoa.orE/prevention/mercurv/imerc/notification/index.cfm
rcury are highly uncertain; DOE will be examining costs of long-term management and storage of elemental mercury
applicable to these compounds. If these compounds were manufactured from surplus domestic elemental mercury,
, though retort costs would remain inapplicable.
Report to Congress
57
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October 14,2009 U.S. Environmental Protection Agency
As shown in Table 4-3, mercury compounds in the United States vary in their potential for use
as exports for the purpose of retorting elemental mercury based on supply costs. The economic
rationale for supply of these compounds for export is summarized below.
> The one compound that is likely to be used as an alternative supply of elemental
mercury is mercury(I) chloride. This compound is currently produced as a waste in
significant quantities, and producers have incentives to avoid retort and storage costs. In
addition, waste mercury(I) chloride is internationally traded, and mercury recyclers in
the United States have purchased waste mercury(I) chloride for the purpose of
recovering elemental mercury for sale.24 It is not clear, however, that global recovery of
elemental mercury from mercury(I) chloride would spread beyond a handful of
sophisticated processors, because the technology for recovery is highly specialized.25
> The other mercury compounds that are possible candidates for production for export to
supplement elemental mercury trade are mercury(II) oxide, mercury(II) sulfate, and
mercury(II) nitrate. Significant capital investment would be required to produce larger
quantities in the United States, and it is not clear that expected quantities of surplus
elemental mercury and anticipated elemental mercury prices are high enough to justify
the investment at this time. However, all of these compounds are commonly produced
and traded for industrial uses in relatively small quantities. Mercury(II) sulfate is also
currently generated as waste, which could possibly be purified for sale or exported. It
does not appear that significant quantities of mercury(II) sulfate are currently processed
to regenerate elemental mercury. Production of mercury(II) nitrate and mercury(II)
sulfate involves the handling of toxic substances such as sulfuric acid and results in
quantities of mercury-containing wastes, which can increase expenses. Mercury(II)
oxide is an interim product of several recovery processes and is relatively simple to
manufacture, though it generally is produced from other compounds, including
mercury(II) sulfate and mercury(I) chloride, and is more inefficient to produce from
elemental mercury. If mercury(I) chloride export is banned, it is possible that
production of mercury(II) oxide could become more cost-competitive. Because
mercury(II) oxide is currently produced as an interim product in processing mercury(I)
chloride, an increase in domestic mercury(I) chloride supplies would likely reduce the
cost of producing mercury(II) oxide.
> Production of other mercury compounds is typically too costly to provide competitive
alternative sources of elemental mercury. Compounds as a source of elemental mercury
for export (e.g., mercury(II) selenide, thimerosal, and mercury(II) thiocyanate) are
currently produced in small quantities for targeted industrial purposes, and require
significant processing and expensive ingredients. Cost-effective bulk production of
these compounds does not appear feasible.
24 While mercury(I) chloride is also manufactured for specific purposes, it does not appear that byproduct
mercury(I) chloride is used as a source for manufactured mercury(I) chloride, or that manufactured mercury(I)
chloride would be a likely substitute source for elemental mercury because, like other manufactured compounds, it
would be more costly than other sources of mercury.
25 In addition, it appears that one stage in this process results in mercury(II) oxide, but it is not clear whether the
quality of mercury(II) oxide is high enough to represent a tradable commodity. The ultimate product of the process is
elemental mercury. See http://www.bethlehemapparatus.com/calomel-conversion.html.
Report to Congress 58
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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October 14,2009 U.S. Environmental Protection Agency
4.4 Summary of Technical and Economic Feasibility of Potential for Export
The current, relatively stable prices and supply of elemental mercury globally, coupled with the
limited capacity of U.S. producers to provide high-volume, low-cost mercury compound
products without investing in new capital equipment, limit the economic opportunity to
manufacture compounds for export as an alternative source of elemental mercury. Unless
mercury compounds are currently traded to provide elemental mercury (as appears to be the
case with recovery of elemental mercury from mercury(I) chloride), it is unlikely that economic
circumstances will favor the development of these markets, even for compounds that are
relatively easy to make and process for regeneration of elemental mercury.
With the exception of capacity for managing mercury (I) chloride and other compounds
produced as byproducts or waste, current compound production capacity in the United States
does not appear sufficient to produce high enough volumes of compounds to compete with
other sources of elemental mercury on the global market. Specialty chemical firms are not
ideally positioned to invest in capital equipment for production of high-volume products,
particularly in a small market. Moreover, most mercury compounds produced by these firms
are fairly complex and have expensive manufacturing processes.
U.S. mercury recyclers, in contrast, have the capacity to process larger volumes of mercury in
waste, and could be positioned to expand operations to produce compounds, but it is not clear
that the limited quantities of elemental mercury likely to be available to these producers would
justify the investment at current elemental mercury prices.
The small quantities of surplus elemental mercury and byproduct compounds available to the
U.S. market limit the financial potential of any effort to develop and trade new compounds. At
recent elemental mercury prices of roughly $600 per flask ($7.90 per pound, $17.42 per
kilogram), the total potential for revenue from an annual surplus production of 125 metric tons
of elemental mercury and mercury compounds is roughly $2.2 million, before subtracting
production costs. While in some cases producers may also be able to charge fees for taking
possession of the elemental mercury or mercury compounds, the potential revenues associated
with this option are highly uncertain.
Absent significant and sustained price increases, this financial potential is not likely to be
sufficient to justify significant investment in new capital equipment, materials, and permits
required to manufacture compounds, export them, and recover elemental mercury.26 While
sustained mercury price increases are possible (e.g., after the EU export ban takes effect in 2011
or in the context of additional treaties restricting supply of elemental mercury), it is difficult to
predict persistent shortfalls in elemental mercury supply given capacity at primary mines and
the range of secondary supply sources. In this context, it is unlikely that mercury compounds
will emerge as a viable alternative source of elemental mercury over the long term.
26 Note that in the case of regeneration of elemental mercury from mercury(I) chloride, the equipment and capacity
for this operation is already in place.
Report to Congress 59
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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October 14, 2009
U.S. Environmental Protection Agency
Table 4-4 summarizes the technological and economic feasibility assessment for the four
compounds deemed most likely to be supplied in significant quantities by U.S. producers. In all
cases except mercury(I) chloride, potential for expansion of operations beyond what is currently
in place is limited by the need to invest in capital equipment and industrial capacity in the
context of uncertain market demand.
Table 4-4: Summary of Assessment of Technical and Economic Feasiblity of Potential for Export
Compound
Mercury (I)
chloride
Mercury (II)
sulfate
Mercury (II)
nitrate
Mercury (II)
oxide
Description
Air pollution
byproduct;
Chemically
manufactured
product
Chemically
manufactured
product;
Waste
treatment
byproduct
Chemically
manufactured
product
Byproduct
Chemically
manufactured
product;
Quantity
Recorded as
Produced or
Sold in the
U.S. by
Reporting
Companies
-25,000 kg
(Hg)*
1.3 Kg
produced
259kg
product;
waste
na
88.7 kg
product
unknown
32.5kg
product
Technical and Economic Feasibility
Summary
Currently traded in large volumes for
regeneration of elemental mercury using
available technology.
Cost-competitive and technologically feasible
source of elemental Hg
Recovered as waste, but requires adoption
of new U.S. production capacity and
technology to process product to
regenerate elemental mercury.
Not currently cost competitive or
technologically feasible given existing capacity
Requires adoption of new U.S. production
capacity and technology to process
product to regenerate elemental mercury.
Not currently cost competitive or
technologically feasible given existing capacity
Occurs as process byproduct including
interim product in regeneration of
mercury from mercury(I) chloride, but
requires adoption of new U.S. production
capacity and technology to process
product to regenerate elemental mercury.
Could become cost competitive if export of
mercury (I) chloride is banned ; however,
existing technological capacity limits
feasibility
Conclusions
Likely
Possible
Possible
Possible
*Quantity of mercury in byproduct mercury(I) chloride; estimate based on discussions with Melissa Barbanell, Barrick Gold
Corporation (personal communication June 18, 2009).
Report to Congress
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
60
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October 14,2009 U.S. Environmental Protection Agency
Mercury(I) chloride is likely to continue to represent an economical source of elemental
mercury, since it is currently traded for this purpose. While three other compounds -
mercury(II) sulfate, mercury(II) nitrate, and mercury(II) oxide - represent possible candidates
for export as alternative sources of elemental mercury, production of these compounds is not
currently cost-competitive with other sources of elemental mercury and production of high
volumes would require additional capital investment.
Report to Congress 61
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October 14,2009 U.S. Environmental Protection Agency
5. Other Relevant Information to Assist Congress in Determining
Whether to Extend the Export Ban
5.1 European Union Ban on Export of Mercury and Mercury Compounds
On October 22, 2008, the European Union expanded its original ban on elemental mercury
exports, introduced in 2007, to include several mercury compounds. The expanded ban
prohibits the export from the European Union of "metallic mercury (elemental mercury),
cinnabar ore, mercury(I) chloride, mercury(II) oxide, and mixtures of metallic mercury with
other substances, including alloys of mercury, with a mercury concentration of at least
95 percent by weight."27 In addition, the EU law prohibits the "mixing of metallic mercury with
a substance for the sole purpose of export of metallic mercury." The implementation date of the
expanded ban is March 15, 2011. The amended export ban excludes elemental mercury or
mercury compounds used for research and development, medical, or analysis purposes.
In general terms, the European Union expressed the opinion that because mercury compounds
are classified as toxic, curbing trade in these compounds would reduce exposure to mercury,
particularly if the compounds are used to recover elemental mercury for further use.28
Cinnebar ore (i.e. mercury (II) sulfide), mercury(I) chloride, and mercury(II) oxide were
included in the export ban because they constitute key ongoing uses of mercury in the
European Union. For example, mercury oxide is currently found and recovered in the European
Union in anodes and in batteries. While mercury oxide batteries are not produced in the
European Union, some production is still ongoing in China and mercury oxide batteries are still
imported into the European Union (Commission of the European Communities, 2006).
Cinnabar ore is no longer mined in the European Union since the last mercury mine closed in
Almaden, Spain, but the European Union perceived an incentive to export cinnabar for
conversion to elemental mercury. Cinnabar ore from Almaden has an exceptionally high
mercury content, and retrieving the elemental mercury is technically simple and inexpensive.
At current elemental mercury prices, the European Union determined that the export of
cinnabar ore and certain other mercury compounds mentioned in EU regulation would still be
profitable after the introduction of the 2011 export ban (Commission of the European
Communities, 2006).
Mercury(I) chloride is used in the European Union in electrochemistry, pesticides, and
cosmetics such as soaps and skin-lightening creams, and is also a byproduct of production of
other non-ferrous metals in Europe (e.g., zinc). The European Union included mercury(I)
chloride in its ban due to concerns that mercury(I) chloride byproduct generated within the
European Union could be exported as a compound for recovery of elemental mercury by a
27 Mercury(II) sulfide as cinnabar ore is abundant in the European Union. In the U.S., however, mercury(II) sulfide
primarily exists as a manufactured product.
28 Draft Report on the proposal for a regulation of the European Parliament and of the Council on the banning of
exports and the safe storage of metallic mercury (COM(2006)0636 - C6-0363/2006 - 2006/0206(COD)) Committee on
the Environment, Public Health and Food, 27 Feb 2007.
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third-country processor at little cost, though the recovery process is sophisticated and requires
several chemical inputs. (Commission of the European Communities, 2006).
5.2 Evidence That Mercury Compounds Are Exported for Processing into
Elemental Mercury
EPA was unable to find any conclusive evidence that compounds are currently exported from
the United States for processing into elemental mercury. The only reference to international
partnerships is the Bethlehem Apparatus reference to its proprietary process for recovering
mercury from mercury(I) chloride : "After consultation with Universal Dynamics of Vancouver,
B.C., Bethlehem Apparatus developed and built a proprietary mercury(I) chloride processing
system."29 This comment implies that at this time, Bethlehem Apparatus is recovering elemental
mercury from mercury(I) chloride domestically, but it also seems feasible that mercury(I)
chloride could potentially be exported in partnership with Universal Dynamics for processing.
http://www .bethlehemapparatus.com/ calomel-con version.html.
Report to Congress 63
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October 14,2009 U.S. Environmental Protection Agency
6. Report Conclusions
Over a dozen mercury compounds are currently manufactured in significant quantities in the
United States, though most of these compounds are manufactured as part of the specialty
chemical industry as value-added products sold in small quantities. In addition, larger volumes
of mercury compounds are produced as byproducts or in mercury-containing waste. The most
significant of these is mercury(I) chloride which is produced by air pollution processes in
several gold mines in quantities exceeding 25 metric tons of elemental mercury per year.
Uses for mercury compounds are typically limited to chemical uses (e.g., preservatives or
process agents) or in other highly specialized industrial applications, and in a limited number of
consumer products such as batteries. At present, the chief mercury compound that is used as a
source of elemental mercury in the United States is mercury(I) chloride.
In addition to domestic production, quantities of mercury compounds are imported to and
exported from the United States. Though data do not identify quantities of individual
compounds traded internationally in recent years, in the early part of the decade, data for
specific compound imports suggested that mercury chlorides (including mercury (I) chloride)
accounted for the majority of imports; mercury traders in the United States have verified that
they have imported mercury(I) chloride and used it as a raw material to regenerate elemental
mercury.
Export data are less informative, in part because recent large reported quantities (exceeding
7,000 tons) are difficult to reconcile with the small size of the global elemental mercury market,
which is estimated at roughly 3,500 metric tons. Currently available data are not sufficient to
describe uses, imports, or exports of specific mercury compounds in detail.
EPA has examined the technological and economical feasibility of the export of 12 mercury
compounds, and found that only mercury compounds produced as byproducts or as part of
waste streams, such as mercury (I) chloride have potential to be cost-competitive if exported as
alternatives for elemental mercury. Mercury (I) chloride is likely to continue to represent an
economical source of elemental mercury, since it is currently traded for this purpose. While
three other compounds - mercury (II) sulfate, mercury (II) nitrate, and mercury (II) oxide -
represent possible candidates for export as alternative sources of elemental mercury, production
of these compounds is not currently cost-competitive with other sources of elemental mercury.
Export on a larger scale would require expansion of U.S. production capacity and would only
be cost-competitive given a much higher global price of elemental mercury.
Although global supply of elemental mercury is difficult to predict with accuracy, a range of
sources of mercury exist outside the United States., and current market information (e.g., the
stability of prices in the last 12 months and continuing downward trends in overall industrial
demand) suggests that elemental mercury will continue to be available in response to demand,
particularly as demand from chlor-alkali plants and other industrial sectors continues to decline
and secondary mercury from some of these facilities also becomes available. As a result, while
supply and price fluctuations are likely, it is difficult to predict a scenario with the sustained
scarcity of and high prices for elemental mercury that would be sufficient to support the
Report to Congress 64
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October 14,2009 U.S. Environmental Protection Agency
development of the infrastructure necessary to develop and export compounds in order to
provide an alternative supply of elemental mercury.
Report to Congress 65
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References
Akhavan, J. 2004. Explosives and propellants. Kirk-Othmer encyclopedia of chemical
technology. John Wiley and Sons. Posted online August 7, 2004.
American Metals Monthly (AMM). 1980-2003. A publication of American Metal Market, LLC.
Comtrade. 2009. U.N. Comtrade Database. Available online at:
http://comtrade.un.org/db/default.aspx. Website accessed April 10, 2009.
Barbanell, Melissa. Barrick Gold Corporation. Personal communication June 18, 2009.
Balco, E.N., W.F. Schmitt, and S.D. Argade. 1977. Mercury recovery and recycle process. United
States Patent US 4,012,297.
Balistreri, E.J. and C.M. Worley. 2007. Mercury: the good, the bad, and the export ban.
Presentation at Mercury Stakeholder Panel Meeting. Washington, D.C. September 20,
2007.
Barreau, G. and C. Eusebe. 1991. Process for preparing metallic mercury from calomel. United
States Patent US 5,071,475.
Baxter, W.C. 1929. Process of extracting mercury from cinnabar. United States Patent US
1,718,103.
Bebout, B.C. 2006. Mercury: inorganic and coordination chemistry. Encyclopedia of inorganic
chemistry. John Wiley and Sons. Posted online March 15, 2006.
Bethlehem Apparatus. 2009a. Calomel Conversion. Available online at:
http: / / www .bethlehemappar atus. com/ c alomel-c onversion.html.
Bethlehem Apparatus. 2009b. Mercury Retirement / Stabilization. Available online at:
http://www.bethlehemapparatus.com/mercury-retirement.html. Accessed May 4, 2009.
Blanch, J.E. and H.M. Majewski. 1978. Process for removing mercury from brine sludges.
United States Patent US 4,124,459.
ChemlDplus Database. 2009. Accessible through United States National Library of Medicine.
TOXNET Toxicology Data Network. Available online at http://toxnet.nlm.nih.gov/.
China Chemicals Registration Center. 2005. China Mercury-related Information Analysis
Report. State Environmental Protection Administration. April 2005.
Chlorine Institute, Inc. 2008. Eleventh Annual Report to EPA, Chlor-Alkali Industry Mercury
Use and Emissions in the United States for the Year 2007. September 26.
Commission for Environmental Cooperation. 2008. Mexican Mercury Market Report. October
2008.
Report to Congress 66
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
-------
October 14,2009 U.S. Environmental Protection Agency
Commission of European Union Communities. 2006. "Mercury flows and safe storage of
surplus mercury." August 2006.
Comtrade. 2009. U.N. Comtrade Database. Available online at:
http://comtrade.un.org/db/default.aspx. Website accessed April 10, 2009.
Concorde East West. 2008. Mercury Compounds in the United States: Uses, Consumption, and
International Trade. Draft Final Report for the U.S. Environmental Protection Agency.
March 2008.
Consumer Product Safety Commission (CPSC). 1997. Part 1507 - Fireworks devices. Code of
Federal Regulations. 16 CFR1507. Available online at
http://frwebgate5.access.gpo.gov/cgi-
bin/PDFgate.cgi?WAISdocID=705443115908+6+2+0&WAISaction=retrieve. Accessed
March 10, 2009.
CrossFire Gmelin Database. 2009. Copyright Elsevier B.V. Available online at
http: / /www.reaxys.com. Accessed February 18, 2009.
DeAngelis, P; Morris, AR; MacMillan, AL. 1978. Apparatus for removing mercury from waste
water. United States Patent US 4,098,697.
DeVito, S.C. and W.E. Brooks. 2005. Mercury. Kirk-Othmer encyclopedia of chemical
technology. John Wiley and Sons. Posted online August 19, 2005
Eckert, M. G. Fleischmann, R. Jira, et al. 2007. Acetaldehyde. Ullmann's encyclopedia of
industrial chemistry, Wiley-VCH Verlag GmbH and Co. KGaA.
Eurochlor. 2008. Chlorine Industry Review 2007 - 2008, An energy intensive industry with a
good story to tell. July 31, 2008.
European Parliament. 2008. Export-ban of mercury and mercury compounds from the European Union
by 2011 [Press Release]. May 22. Available online at:
http://www.europarl.europa.eu/sides/getDoc.do?language=EN&type=IM-
PRESS&reference=20080516BRI29011&secondRef=ITEM-008-EN.
European Parliament Committee on the Environment, Public Health and Food Safety. 2007.
Draft Report on the proposal for a regulation of the European Parliament and of the
Council on the banning of exports and the safe storage of metallic mercury.
COM(2006)0636 - C6-0363/2006 - 2006/0206(COD). February 27, 2007.
Eurostat. 2009. Available online at:
http://epp.eurostat.ec.europa.eu/portal/page/portal/eurostat/home/.
Falbesaner, E. J. Bichler, and E. Wimmer. 1980. Process for removal of mercury and mercury
compounds from aqueous solutions and industrial waste liquors. United States Patent
US 4,234,422.
Report to Congress 67
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
-------
October 14,2009 U.S. Environmental Protection Agency
Fisher Scientific. 2009. Available online at: http://www.fishersci.com. Website accessed April
10, 2009.
Foulkes, E. 2001. Mercury. Patty's toxicology. John Wiley and Sons. Posted online April 16,
2001.
Foust, D.F. 1993. Extraction of mercury and mercury compounds from contaminated material
and solutions. United States Patent US 5,226,545.
Foust, D.F. 1994. Extraction of mercury and mercury compounds from contaminated material
and solutions. International Patent WO 94/09167.
Gerow R.F. and S.B. Soule. 1972. Recovery of mercury from mercurous bearing liquids. United
States Patent US 3,802,910.
Grossman, M.W. and W.A. George. 1991. Recovery of mercury from mercury compounds via
electrolytic methods. United States Patent US 5,024,738.
Grossman, M.W. and W.A. George. 1989. Recovery of mercury from mercury compounds via
electrolytic methods. United States Patent US 4,879,010.
Gurjar Chemicals. 2009. Personal Communication with Mr. Mandloi. April 10, 2009. Available
online at: http:/ /gurjarchemicals.com/?page=default. Website accessed April 10, 2009.
Hojdova, M., T. Navratil, and J. Rohovec. 2008. Distribution and speciation of mercury in mine
waste dumps. Bull Environ Toxicol DOI 10.1007/s00128-007-9352-y.
Hazardous Substances Data Bank (HSDB). 2009. Accessible through United States National
Library of Medicine. TOXNET Toxicology Data Network. Available online at:
http: / /to xnet.nlm.nih.gov/.
H.R. 2190: Mercury Pollution Reduction Act. Introduced April 30, 2009. Available online at:
http://thomas.loc.gov/cgi-bin/query/z?clll:H.R.+2190:
International Council on Mining and Metals. 2009. Available online at: www.icmm.com.
Inventory Update Reporting Database (IUR Database). 2009. Last update February 4, 2009.
Available online at: http://www.epa.gov/iur/tools/data/index.htm
Jasinski, S.M. 1994. The materials flow of mercury in the United States. U.S. Bureau of Mines
Information Circular 9412, Version 1.0.
Jones, G. and G. Miller. 2005. Mercury and Modern Gold Mining in Nevada. Reno, NV:
University of Nevada Department of Natural Resources and Environmental Sciences.
Available online at:
http://www.chem.unep.ch/Mercury/Trade%20information/NRDC-
NEVADABYPRODUCTRECOVERYREPORT.pdf. Accessed February 5, 2009.
Lawrence, B. 2007. Personal Communication on August 13, 2007.
Report to Congress 68
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
-------
October 14,2009 U.S. Environmental Protection Agency
Lewis, R.J. 1997. Hawley's condensed chemical dictionary. 13th edition. New York: John Wiley
& Sons, Inc.
Linstrom, P.J and W.G. Mallard. 2009. NIST Chemistry WebBook, NIST Standard Reference
Database Number 69. National Institute of Standards and Technology, Gaithersburg
MD, 20899. Available online at: http: / /webbook.nist.gov. Accessed March 2, 2009.
Louie, D.K. 2005. Handbook of Sulfuric Acid Manufacturing. Ontario: DKL Engineering, Inc.
Martin, D., K. Burgess, and T. Leonard. 2004. Battery reclamation system. United States Patent
US 6,686,086 Bl.
Materials Transportation Bureau (MTB). 1978. Hazardous materials table and hazardous
materials communications regulations, forbidden materials. 49 CFR Part 172.
Department of Transportation. Federal Register 43(37). Available online at
http: / / phmsa. dot, go v/ staticfiles / PHMSA / Do wnloadableFiles / Files / Federal % 20Regist
er%20Historical%20Files/43fr 1978743fr-7449.pdf. Accessed March 10, 2009.
Maxson, P. 2009. EPA internal draft: Mercury Compounds in the United States: uses, consumption,
and international trade. Concorde East West Sprl. March 2009.
Maxson, P. 2006. Mercury flows and safe storage of surplus mercury. Concorde East/West Sprl
for the European Commission - DC Environment, August 2006, Brussels.
Mercury Export Ban Act of 2008. 2008. Pub. L. No. 110-414,122 Stat. 4341-4348.
Metal Bulletin. 2005. "Price Archive: Mercury." Available online at:
http: / /www.metalbulletin.com. Accessed April 25, 2005.
Mining Journal. 2005 - 2007 (Assorted dates). "Production and Markets."
Misra, M., K. Yang, and R.K. Mehta, "Application of fly ash in the agglomeration of reactive
mine tailings," Journal of Hazardous Materials, 51 [1-3] 181-192 (1997).
National Biennial Reporting System. Available online at:
http://www.epa.gov/waste/inforesources/data/biennialreport/index.htm
Natural Resources Defense Council (NRDC). 2007. China Facts, NRDC Fights to Stop Mercury
Pollution in China: China is Cornerstone in Solving Global Mercury Problem. April
2007.
Nevada Administrative Code. 2006. Nevada Mercury Air Emissions Control Program. NAC
445B.3611-3689. Available online at: http://www.leg.state.nv.us/NAC/NAC-
445B.html#NAC445BSec3611. Accessed February 11, 2009.
Nevada Bureau of Air Pollution Control. 2006. Calendar Year 2006 Actual Production/Emission
Reporting Form Addendum for Mercury Emissions. Available online at:
http://ndep.nv.gov/baqp/hg/2006 AERpdf. Accessed February 11, 2009.
Report to Congress 69
Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
-------
October 14,2009 U.S. Environmental Protection Agency
Nevada Bureau of Air Pollution Control. 2007. Calendar Year 2007 Actual Production/Emission
Reporting Form Addendum for Mercury Emissions. Available online at:
http://ndep.nv.gov/baqp/hg/2007 AERpdf Accessed February II, 2009.
Nevada DEP. 2009. NMCP Wiki. Available online at: http://ndep.nv.gov/baqp/hg/wiki.pdf
Nguyen, X.T. 1979 Process for mercury removal. United States Patent US 4,160,730.
Nordic Council of Ministers. 2007. Mercury substitution priority working listAn input to
global considerations on mercury management. May 2007.
Northeast Waste Management Officials' Association (NEWMOA). 2009. IMERC Raw Data.
NEWMOA. "IMERC Mercury Added Products Database/' Available online at:
http://www.newmoa.org/prevention/mercury/imerc/notification/index.cfm
NEWMOA. 2008. Trends in Mercury Use in Products. Available online at:
http: / / www.newmoa. or g/ prevention/ mercury / imerc / f actsheets/ mercuryinproducts.
pdf
NEWMOA. 2008. Supplemented with personal communication with Adam Wienert, April 9,
2009.
Nowak, M. and W. Singer. 1995. Mercury compounds. Kirk-Othmer encyclopedia of chemical
technology. John Wiley and Sons. Posted online December 4, 2000.
O'Neil, M.J., A. Smith, P.E. Heckelman, et al. 2001. The Merck index, 13th edition. Whitehouse
Station: Merck and Co., Inc.
Patnaik, P. 2003. Handbook of inorganic chemicals, monographs 559 (mercury) through 580
(mercury [II] sulfide). New York: McGraw-Hill. Available online at
http://library.ukrweb.net/book/chemistry/inorganic/patnaik%20p.%20-
%20handbook%20of%20inorganic%20chemicals/94398 toc.pdf.
Pitton, OA. 1994. Removal of mercury from waste streams. United States Patent US 5,292,412.
Pollara, J. 2007. Newmont Mining Corporation. Personal Communication. July 25 and
September 20.
Robinson, J.M. 1992a. Removal of mercury from waste streams. United States Patent US
5,154,833.
Robinson, J.M. 1992b. Removal of mercury from waste stream. European Patent Application EP
0 550 967 Al.
Rossberg, M, W. Lendle, G. Pfleiderer, et al. 2006. Chlorinated hydrocarbons. Ullmann's
encyclopedia of industrial chemistry. Wiley-VCH Verlag GmbH and Co. KGaA.
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October 14,2009 U.S. Environmental Protection Agency
S. Rep. No. 110-477. 2008. Senate Report 110-477 - Mercury Market Minimization Act of 2007.
Available online at: http://frwebgate.access.gpo.gov/cgi-
bin/getdoc.cgi?dbname=110_cong_reports&docid=f:sr477.110.pdf
Simon, M., P. Jonk, C. Wuhl, et al. 2006. Mercury, mercury alloys, and mercury compounds.
Ullmann's encyclopedia of industrial chemistry. Wiley-VCH Verlag GmbH and Co.
KGaA. Posted online December 15, 2006.
Speigel, S.J. and M.M. Veiga. 2006. Global Impacts of Mercury Supply and Demand in Small-
Scale Gold Mining. Report to the UNEP Governing Council Meeting, Nairobi, February
2007. Report prepared by the United Nations Industrial Development Organization.
October 2006.
State of Nevada. 2006. Nevada Mercury Control Program (NMCP) Overview and Guidance,
July 2006. Nevada: Department of Conservation and Natural Resources, Division of
Environmental Protection. Available online at:
http://ndep.nv.gov/baqp/hg/white sheet.pdf. Accessed February 10, 2009.
Takacs, L. 2000. Quicksilver from cinnabar: the first documented mechanochemical reaction?
Journal of the Minerals, Metals and Materials Society 58(1):12-13.
Tessele, F., M. Misra, and J. Rubio. 1998. "Removal of Hg, As and Se ions from gold cyanide
leach solutions by dissolved air flotation" Minerals Engineering, Vol. 11, No. 6, pp. 535
543.
Toxnet Hazardous Substances Database. 2008a. Mercury Compounds. Available online at:
http://toxnet.nlm.nih.gov/. Accessed December 17, 2008.
Toxnet Hazardous Substances Database. 2008b. Mercury fulminate. Available online at:
http://toxnet.nlm.nih.gov/. Accessed December 18, 2008.
UNEP 2009. United Nations Environment Programme Governing Council / Global Ministerial
Environmental Forum. "Decisions 25/5, Chemicals management, including mercury."
February 2009.
UNEP. 2008. Report on the current supply of and demand for mercury, including the possible
phase-out of primary mercury mining. Report Prepared by P. Maxson. July 14, 2008.
U.S. Department of Transportation (U.S. DOT). 2009. Hazardous materials transportation
guides. Research and Innovative Technology Administration (RITA). National
Transportation Library. Available online at http://ntl.bts.gov/DOCS/hmtg.html.
Accessed February 23, 2009.
U.S. Environmental Protection Agency (U.S. EPA). 2009a. Mercury: Frequent Questions.
http://epa.gov/mercury/
U.S. EPA 2009b. TRI.NET Database. Queried March 16, 2009. http://www.epa.gov/triexplorer
Report to Congress 71
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October 14,2009 U.S. Environmental Protection Agency
U.S. EPA. 2009c. Mercury: consumer and commercial products. Available online at
http://www.epa.gov/mercury/consumer.htm. Accessed February 23, 2009.
U.S. EPA. 2008a. Toxic Chemical Release Inventory Reporting Forms and Instructions. EPA
Document 260-K-07-001. http://www.epa.gov/tri/report/rfi/2007rfi.pdf
U.S. EPA. 2008b. Mercury Containing Products Database. Available online at:
http://www.epa.gov/mercury/database.htm
U.S. EPA. 2007a. Treatment technologies for mercury in soil, waste, and water. Office of Superfund
Remediation and Technology Innovation. Available online at:
http://www.epa.gov/tio/download/remed/542r07003.pdf
U.S. EPA. 2007b. Mercury Storage Cost Estimates, final report, November 6, 2007
U.S. EPA. 2007c. National Listing of Fish Advisories 2007. Available online at:
http://www.epa.gov/waterscience/fish/advisories/index.html
U.S. EPA. 2006. EPA's Roadmap for Mercury. EPA-HQ-OPPT-2005-0013.
http://www.epa.gov/mercury/roadmap.htm
U.S. EPA. 1997a. Mercury Study Report to Congress. EPA-452/R-97-003. Office of Air Quality
Planning and Standards and Office of Research and Development. December 1997.
U.S. EPA. 1997b. Locating and Estimating Air Emissions from Sources of Mercury and Mercury
Compounds. EPA-454/R-97-012. Available online at:
http://www.epa.gov/ttn/chief/le/mercury.pdf. Accessed December 17, 2008, from
U.S. EPA. Substance Registry Services (SRS). Available online at:
http://iaspub.epa.gov/sor_internet/registry/substreg/home/overview/home.do
U.S. EPA. 1990. Final BOAT Background Document for Mercury-Containing Wastes D009,
K106, P065, P092, and U151,USEPA, May 1990.
U.S. EPA and U.S. Food and Drug Administration (U.S. FDA). Joint fish consumption advisory.
What you need to know about mercury in fish and shell fish. Available online at:
http://www.epa.gov/waterscience/fish/files/MethylmercuryBrochure.pdf
U.S. FDA. 2009a. Mercury in drug and biologic products. Center for Drug Evaluation and
Research. Available online at http://www.fda.gOv/cder/fdama/.htm. Accessed
February 27, 2009.
U.S. FDA. 2009b. Thimerosal in vaccines. Center for Biologies Evaluation and Research.
Available online at http://www.fda.gov/cber/vaccine/thimerosal.htm. Accessed
February 27, 2009.
United States Geological Survey (USGS). 2009. Mineral Commodity Summary: Mercury.
Available online at:
http://minerals.usgs.gov/minerals/pubs/commodity/mercury/mcs-2009-mercu.pdf.
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USGS. 1998. Metal Prices in the United States through 1998: Mercury. Available online at:
http://minerals.usgs.gov/minerals/pubs/metaLprices/.
U.S. International Trade Commission (U.S.ITC). 2009. Interactive Tariff and Trade Dataweb.
Available online at: http://dataweb.usitc.gov/. Accessed April 10, 2009.
U.S. ITC. 2008. Imports for consumption: mercury and mercury chlorides. Retrieved December 19,
2008, from http://dataweb.usitc.gov/scripts/user_set.asp
U.S. ITC. 2006. Harmonized Tariff Schedule of the United States 2006 (USITC Publication 3833).
Available online at: http://www.usitc.gov/tata/hts/bychapter/_0600.htm
U.S. ITC. 2006. Proposed Modifications to the Harmonized Tariff Schedule of the United States (USITC
Publication 3851). April. Available online at:
http://hotdocs.usitc.gov/docs/tata/hts/Pub3851.pdf
Weast, R.C. 1983-1984. CRC Handbook of Chemistry and Physics, 64th edition. Boca Raton:
Taylor and Francis.
Weiss, S. and A.R. Lechugs. 1983. Mercury brine sludge treatment. United States Patent US
4,381,288.
Wilhelm, S.M. 1999. Generation and disposal of petroleum processing waste that contains
mercury. Environmental Progress 18(2):130-143.
Wisconsin Department of Natural Resources (Wisconsin DNR). 1997. Wisconsin Mercury
Sourcebook. "Mercury Use: Agriculture." Available online at:
www.epa.gov/glnpo/bnsdocs/hgsbook/agr.pdf
Yang, H, Z. Xu, M. Fan, et al. 2007. Adsorbents for capturing mercury in coal-fired boiler flue
gas. J Hazar Mater 146:1-11.
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U.S. Environmental Protection Agency
Appendix A - Mercury Compound Identifying Information
Table A-l: Identifying Information for Mercury Compounds in This Report
Compound
Mercury (I)
chloride
Mercury (II)
acetate
Mercury (II)
chloride
Mercury (II)
iodide
Mercury (II)
nitrate
Mercury (II)
oxide
Mercury (II)
selenide
Mercury (II)
sulfate
Mercury (II)
sulfide
Mercury (II)
thiocyanate
Phenylmercury
(II) acetate
Thimerosal
CAS
Number
10112-91-1
1600-27-7
7487-94-7
7774-29-0
10045-94-0
21908-53-2
20601-83-6
7783-35-9
1344-48-5
592-85-8
62-38-4
54-64-8
Alternate Names
Mercurous
chloride
Mercuric acetate,
Diacetoxymercury,
Mercuric diacetate,
Mercuric chloride
Mercuric iodide
Mercuric nitrate
Mercuric oxide
None
Mercuric sulfate
Mercuric sulfide,
cinnabar
Mercuric
thiocyanate
PMA
Sodium
Ethylmercurithio-
salicylate,
Merthiolate,
Thiomersal
Description
Heavy white
powder or
colorless crystals
Colorless
crystalline solid
Toxic and
corrosive white
powder
Red or yellow
powder
White or slightly
yellow powder
Red, orange, or
yellow powder
ultrapure 100
mesh powder
White granules
or crystalline
powder
Red hexagonal
crystals or black
cubic crystals
White to tan
powder
White crystalline
powder or white
prisms
Cream colored
crystalline
powder
Mercury
by
Molecular
Weight
85%
63%
74%
44%
62%
93%
68%
86%
63%
60%
49%
Uses
Electrochemistry;
Mining by-product
Production of
organomercuric
compounds.
Laboratory chemistry;
Waste treatment
Laboratory chemistry;
Veterinary medicine;
Nuclear particle
detection
Laboratory chemistry
Laboratory chemistry;
Batteries
Electrochemistry
Laboratory chemistry;
Gold and silver
extraction
Mercury extraction;
Waste; Pigment
Laboratory chemistry;
Photography
Pharmaceutical;
Production of
phenylmercury
compounds
Pharmaceutical
Production Status
Currently
manufactured^;
Mining byproduct
Currently
manufacturedd
Currently
manufactured^
Currently
manufactured2'13
Currently
manufactured2'13
Currently
manufactured2'13
Waste from
production of
semiconductors
and integrated
circuitry
Currently
manufactured2
Currently
manufactured0;
Waste; Naturally
occurring
Currently
manufactured2'13
Currently
manufactured0
Currently
manufactured2'13
"Based on 2004 NEWMOA data.
bAccording to EPA's 1997 report to Congress.
cBased on chemical supplier websites.
dAccording to Simon et al. (2006)
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Potential Export of Mercury Compounds from the United States for Conversion to Elemental Mercury
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U.S. Environmental Protection Agency
Appendix B - Mercury Compounds in the IUR Database
The six chemicals identified as those with the production levels of greater than 25,000 pounds
(11,340 kilograms) or greater at a single site according to the IUR database were selected for in-
depth review. The purpose of the IUR program is to collect quality screening-level, exposure-
related information on chemical substances and to make that information available for use by
EPA and, to the extent possible while still protecting confidential business information, to the
public. The IUR regulation requires manufacturers and importers of certain chemical substances
included in the TSCA Chemical Substance Inventory to report site and manufacturing
information for chemicals (including imported chemicals) manufactured in amounts of 25,000
pounds (11,340 kilograms) or greater at a single site. Additional information on domestic
processing and use must be reported for chemicals manufactured in amounts of 300,000 pounds
(136,078 kilograms) or more at a single site. The IUR data are used to support risk screening,
assessment, priority setting and management activities and constitute the most comprehensive
source of basic screening-level, exposure-related information on chemicals available to EPA.
EPA searched the databases from 1986 through 2006 for any mercury compound or elemental
mercury (not included in this Report to Congress) that met the listing criteria stated above.
Table A2-1: Identifying information for mercury compounds in this report
CAS No.
62384
1600277
7487947
10112911
26545493
1986
10K-500K
>1M - 10M
No Reports
No Reports
No Reports
1990
10K-500K
No Reports
10K - 500K
No Reports
10K - 500K
1994
No Reports
No Reports
No Reports
No Reports
No Reports
1998
No Reports
No Reports
No Reports
10K-500K
No Reports
2002
>1M - 10M
No Reports
No Reports
No Reports
No Reports
2006
No Reports
No Reports
< 500,000
No Reports
No Reports
Chemical Name
Mercury, (acetato-
.kappa.O)phenyl-
Aceh'c acid,
mercury(2+) salt
Mercury chloride
(HgC12)
Mercury chloride
(Hg2C12)
Mercury,
(neodecanoato-
.kappa.O)phenyl-
There are limitations to using IUR data. The main limitation is that if no chemical was
manufactured in the year reporting was done then that chemical could go completely unnoticed
if only IUR data were used. Note that mercury(II) oxide is not on the list but is an intermediate
to several of the listed chemicals.
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Appendix C - Individual Mercury Compound Summaries
C.I Mercury(II) acetate
Formula: Hg(C2H3C>2)2
Percent mercury by weight: 63
CAS Index Name : Acetic acid, mercury(2+) salt (2:1)
CASRN: 1600-27-7
Synonyms: Mercuric acetate, Diacetoxymercury, Mercuric diacetate, Mercury diacetate (HSDB,
2009)
C.I.I Product description
Mercury(II) acetate is a colorless crystalline solid that melts at about 178ฐC. It will decompose at
higher temperatures or when heated rapidly. Mercury(II) acetate is soluble in water, but the
solution decomposes on standing to produce a yellow precipitate. Mercury(II) acetate is soluble
in alcohol (Patnaik, 2003).
C.1.2 Product uses
Mercury(II) acetate is primarily used as a starting material for the manufacture of
organomercuric compounds, including phenylmercury(II) acetate. Mercury(II) acetate is also
used as a catalyst in organic polymerization reactions and as a reagent in analytical chemistry
(Simon et al, 2006).
C.1.3 Synthesis from mercury
Mercury(II) acetate is typically prepared from other common mercury compounds. For
example, heating mercury(II) oxide in a slight excess of warm 20% acetic acid will produce
mercury(II) acetate. Mercury(II) oxide feedstock for this process can be obtained in commercial
quantities, or can itself be readily prepared in one or two steps from elemental mercury and
commercially available compounds. More information on the production of mercury(II) oxide is
presented in its chemical summary.
Mercury(II) acetate can also be prepared directly from elemental mercury by reaction with
peracetic acid dissolved in acetic acid. This reaction is quite exothermic and needs to be
carefully controlled. A more economical method is to use 50% hydrogen peroxide instead of
peracetic acid, but the reaction does not go quite as smoothly (Nowak and Singer, 1995).
C.1.4 Reduction to elemental mercury
Mercury(II) acetate will decompose when heated or when exposed to light (O'Neil et al., 2001).
It is unclear whether this decomposition leads directly to elemental mercury or to mercury(II)
oxide. Either reaction can lead to the eventual release of elemental mercury. Mercury(II) oxide is
reduced to elemental mercury and oxygen when heated. More information on the reduction of
mercury(II) oxide is presented in its chemical summary.
In aqueous solution, mercury(II) acetate slowly hydrolyzes to form acetic acid and mercury(II)
oxide (CrossFire Gmelin Database, 2009). As noted above, this can lead to the eventual release
of elemental mercury from mercury(II) oxide decomposition (O'Neil et al., 2001).
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C.1.5 Potential sources
Sources of mercury(II) acetate include manufacturing facilities or sites where it is used as an
intermediate in the manufacture of other organomercuric compounds.
C.1.6 Potential for export as an alternative to mercury
Mercury(II) acetate can be prepared directly from elemental mercury in a single step requiring
inexpensive reagents. Mercury(II) acetate can also be prepared from other common mercury
compounds in a single synthetic step that can be accomplished using basic equipment and
inexpensive reagents. Elemental mercury can be obtained by heating mercury(II) acetate and
condensing the vapor. This process can be accomplished using basic equipment. Mercury(II)
acetate is a stable solid and is used in a number of commercial applications. It is easy to handle
and can be transported using standard methods.
Mercury(II) acetate is a potential candidate for export as a mercury source because of its
following attributes:
It is available in commercial quantities or can be readily prepared from commercially
available materials;
It can be transported easily; and
It produces elemental mercury simply by heating and condensing the resulting vapor.
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C.2 Mercury(I) chloride
Formula: Hg2Cl2
Percent mercury by weight: 85
CAS Index Name: Mercury chloride (Hg2C12)
CASRN: 10112-91-1
Synonyms: Mercurous chloride, Calomel, Calogreen, Calotab, Dimercury dichloride, Mercury
protochloride (Linstrom and Mallard, 2009)
C.2.1 Product description
Mercury(I) chloride, also known as calomel, is a white powder and has a low aqueous solubility
of 2 mg/L. It sublimes without melting when heated to 400-500ฐC, but this occurs at least in
part as a result of dissociation to elemental mercury and mercury(II) chloride (Nowak and
Singer, 1995). Dissociation of mercury (I) chloride is also promoted by sunlight and by reaction
with solutions of alkali iodides, bromides, or cyanides (O'Neil et al., 2001).
Mercury(I) chloride is available as a powder in quantities from 25 g to 2.5 kg (EPA Mercury
Containing Products Database, 2008).
C.2.2 Product uses
Mercury(I) chloride is primarily used in calomel (mercury(I) chloride) electrodes, which act as
standard electrodes for measuring electrochemical potential. Mercury(I) chloride can also be
used in pyrotechnics to produce a dark green light, although mercury salts are prohibited in
consumer fireworks in the United States, by Federal law (CPSC, 1997).
Mercury(I) chloride was formerly used as an antiseptic and as a treatment for syphilis before
the advent of penicillin (Patnaik, 2003). It was also formerly used as a fungicide and in
agriculture for controlling root maggots. In the late 1970s, the United States restricted the
acceptable pesticide uses of mercury to the treatment of outdoor textiles and to the control of
fungal pests, particularly brown mold on freshly sawn lumber, Dutch elm disease, and snow
mold. In 1991, the EPA announced the cancellation of mercury biocide registrations (DeVito and
Brooks, 2005) eliminating this use for mercury(I) chloride.
C.2.3 Synthesis from mercury
Mercury(I) chloride is typically prepared by passing a limited amount of chlorine gas over
mercury in a heated silica retort. The use of excess chlorine will result in oxidation of mercury(I)
chloride to mercury(II) chloride (HgCb) (Patnaik, 2003). The use of the highly toxic and
corrosive chlorine limits this synthetic procedure to appropriately equipped facilities.
Mercury(I) chloride can also be prepared from other mercury compounds using basic
laboratory transformations. For example, mercury(I) chloride is obtained as a white precipitate
by adding a cold acidic solution of sodium chloride to a solution of mercury(I) nitrate.
Mercury(I) nitrate is, in turn, prepared by the action of moderately dilute nitric acid on
elemental mercury (Patnaik, 2003). Mercury(I) chloride can also be prepared by heating
mercury(II) chloride with elemental mercury (Bebout, 2006). Mercury(II) chloride can be
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obtained in commercial quantities, or can itself be readily prepared in one or two steps from
elemental mercury and commercially available compounds. More information on the
production of mercury(II) chloride is presented in its chemical summary.
C.2.4 Reduction to elemental mercury
Elemental mercury can be obtained from mercury(I) chloride by electrochemical reduction
using an electrolyte solution comprised of aqueous hydrochloric acid and collecting the
resulting liquid metal (Grossman and George, 1991,1989).
Chemical reduction of mercury(I) chloride can be accomplished by reaction with non-
amalgamating metals, such as iron. In a typical process, mercury(I) chloride in a suspension can
be reduced by addition of iron powder with agitation. The product, elemental mercury, falls out
and is cleaned with aqueous nitric acid (Barreau, 1991).
Mercury(I) chloride can also be converted to other mercury compounds, which can then
subsequently be reduced to elemental mercury. For example, when heated with additional
chlorine, mercury(I) chloride is oxidized to mercury(II) chloride. Mercury(II) chloride can be
converted to mercury(II) oxide, which is reduced to elemental mercury and oxygen by heating.
More information on the synthesis and reactions of mercury(II) chloride and mercury (II) oxide
is presented in their chemical summaries.
Mercury(I) chloride is dissociated by sunlight or by heating in an open container. Both of these
processes can be used to produce elemental mercury using simple equipment. Reaction of
mercury(I) chloride with solutions of alkali iodides, bromides, or cyanides produces mercury(II)
salt and elemental mercury (O'Neil et al., 2001). However, these reactions yield only half of the
elemental mercury as other reactions as half of the metal ends up as the mercury(II) salt.
Mercury(I) chloride can be reduced to elemental mercury by reaction with 2-amino-ethanethiol
hydrochloride in water (CrossFire Gmelin Database, 2009). Similarly, other conversions of
mercury(I) chloride to elemental mercury have been reported in the literature. It is unclear if
these methods are useful for producing large quantities of elemental mercury.
C.2.5 Potential sources
Mercury(I) chloride is a common product from waste treatment methods used in a variety of
industries. One such method is the Boliden-Norzink process, which is used to remove mercury
from flue gases resulting from the burning of natural gas or the refining of zinc, gold, copper, or
other metals where elemental mercury is an impurity. In the Boliden-Norzink process, flue
gasses containing elemental mercury are washed with an aqueous solution of mercury(II)
chloride and the resulting water-insoluble mercury(I) chloride precipitates out of solution
(Louie, 2005).
Mercury(I) chloride is also a waste from the chlor-alkali industry in which mercury metal is
used as a cathode material in the electrochemical generation of chlorine gas from brine (U.S.
EPA, 2007a).
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Mercury(I) chloride could be obtained through the disassembly or destruction of calomel
electrodes. However, this process would be labor intensive and only small quantities are
present within each electrode.
C.2.6 Potential for Export as an Alternative to Mercury
Mercury(I) chloride is a waste from a wide variety of industrial processes. Mercury(I) chloride
can be prepared directly from elemental mercury in a single step requiring only that it be
heated in the presence of chlorine. Mercury(I) chloride can also be prepared from other mercury
compounds in a single synthetic step that can be accomplished using basic equipment and
inexpensive reagents. Elemental mercury can be obtained by either chemical or electrochemical
reduction of mercury(I) chloride, and collecting the resulting liquid metal. These processes can
be accomplished using basic equipment and inexpensive reagents. Mercury(I) chloride is a
stable solid and is used in a number of commercial applications. It is easy to handle and can be
transported using standard methods.
Mercury(I) chloride is a potential candidate for export as a mercury source because of its
following attributes:
It is commercially available;
It is a common waste from a wide variety of industries;
It can be prepared from commercially available materials using straight-forward
methods;
It can be transported easily; and
It can be converted to elemental mercury using a number of techniques and process,
some of which do not require complicated equipment or procedures.
Concern was raised in Europe that mercury(I) chloride waste from the Boliden-Norzink process
could be exported from the European Union as a mercury waste or as a compound, and the
mercury could be recovered inexpensively outside the European Union (European Commission
Directorate General for Environment, 2006); the EU's mercury export ban was amended in
October of 2008 to include mercury compounds.
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C.3 Mercury(II) chloride
Formula: Hg Cb
Percent mercury by weight: 74
CAS Index Name : Mercury chloride (HgC12)
CASRN: 7487-94-7
Synonyms: Mercuric chloride, Mercury perchloride, Mercury bichloride, Mercuric bichloride,
Mercury dichloride, Corrosive sublimate (Linstrom and Mallard, 2009)
C.3.1 Product description
Mercury(II) chloride is a white crystalline solid that melts at 276ฐC. It sublimes without
decomposition at 304ฐC. Mercury(II) chloride has a high vapor pressure of 5 torr at 166ฐC and
60 torr at 222ฐC; at which temperatures, it is still a solid. Mercury(II) chloride is water soluble
(7.4 g/100 ml at 20ฐC). The solubility of mercury(II) chloride increases in aqueous hydrochloric
acid or chloride ion solutions. Mercury(II) chloride is also soluble in alcohol, ether, acetone, and
ethyl acetate (Patnaik, 2003).
Mercury(II) chloride is sold as a powder in 100 g, 125 g, 250 g, 500 g, 1.0 kg, 2.5 kg, and 50 kg
containers. The compound also appears to have been offered by one company as a 5% solution,
the sale of which was discontinued in 2005. (EPA Mercury Containing Products Database, 2008)
C.3.2 Product uses
Mercury(II) chloride is used as an intermediate for the preparation other mercury compounds
including red and yellow mercury(II) oxide, ammoniated mercury, and mercury(II) iodide, and
as an intermediate in organic synthesis (Nowak and Singer, 1995). Mercury(II) chloride is used
in the Boliden-Norzink process to remove mercury from flue gases resulting from the burning
of natural gas or the refining of zinc, gold, copper, or other metals where elemental mercury is
an impurity. Other applications include processes for etching steel and electroplating aluminum
(O'Neil et al, 2001).
Until about 1980, mercury(II) chloride was used extensively as a catalyst for the preparation of
vinyl chloride from acetylene. Since the early 1980s, vinyl chloride and vinyl acetate have been
prepared from ethylene instead of acetylene, and the use of mercury(II) chloride as a catalyst
has practically disappeared (DeVito and Brooks, 2005).
Other former uses include using mercury(II) chloride as an intensifier in photography; for
preserving wood and anatomical specimens, including embalming; for tanning leather; as a
fungicide; as a depolarizer for dry batteries; and as an antiseptic (O'Neil et al., 2001). The 1996
U.S. Mercury-Containing Battery Management Act limited the use of mercury in batteries to
mercury oxide batteries and small quantities of elemental mercury added to batteries to prevent
the buildup of hydrogen gas. In the late 1970's, the United States restricted the acceptable
pesticide uses of mercury to the treatment of outdoor textiles and to control of fungal pests,
particularly brown mold on freshly sawn lumber, Dutch elm disease and snow mold (DeVito
and Brooks, 2005).
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C.3.3 Synthesis from mercury
Mercury(II) chloride is typically manufactured by heating mercury with excess chlorine.
Purification of mercury(II) chloride in this process takes advantage of its low sublimation
temperature as the resulting sublimate is collected (Patnaik, 2003). The use of the highly toxic
and corrosive chlorine limits this synthetic procedure to appropriately equipped facilities.
Mercury(II) chloride can also be prepared from other commonly available mercury compounds.
For example, the treatment of mercury(II) oxide with aqueous hydrochloric acid produces
mercury(II) chloride which is separated by crystallization. An alternative method is to heat
mercury(II) sulfate with sodium chloride to produce mercury(II) chloride, which vaporizes
under these conditions; the sublimate is then condensed and collected (Patnaik, 2003). The
mercury(II) oxide or sulfate feedstocks for these processes can be obtained in commercial
quantities, or can themselves be readily prepared in one or two steps from elemental mercury
and commercially available compounds. More information on the production of mercury(II)
oxide and mercury(II) sulfate is presented in their chemical summaries.
C.3.4 Reduction to elemental mercury
Mercury(II) chloride reacts with tin(II) chloride to give a white precipitate of mercury(I)
chloride which then is further reduced by tin(II) chloride to give a black deposit of mercury
(Patnaik, 2003). It can also be electrochemically reduced to elemental mercury and chlorine
using a mercury metal cathode (Louie, 2005).
Mercury(II) chloride can be converted using standard solution chemistry to other mercury
compounds, which can subsequently be reduced to elemental mercury (Patnaik, 2003). For
example, mercury(II) chloride can be converted to red mercury(II) oxide by heating in a solution
of sodium carbonate. Mercury(II) chloride can also be converted to yellow mercury(II) oxide by
dissolving it in water and treating it with a strongly alkaline reagent, typically sodium
hydroxide. An aqueous solution of mercury(II) chloride can be treated with an excess of
hydrogen sulfide or sodium sulfide to produce mercury(II) sulfide as a precipitate. The
mercury(II) oxide or mercury(II) sulfide produced in these processes can be reduced to
elemental mercury by heating. More information on the reduction of mercury(II) oxide and
mercury(II) sulfide is presented in their chemical summaries.
C.3.5 Potential sources
Potential sources of mercury(II) chloride are from the facilities where it is manufactured or
used. Those laboratories that use mercury(II) chloride as a catalyst or reagent, and industries
that use mercury(II) chloride to capture mercury as part of their waste control procedures, are
likely to have the highest amounts of this compound present on-site.
C.3.6 Potential for export as an alternative to mercury
Mercury(II) chloride is commercially available. It can be prepared directly from elemental
mercury in a single step requiring only that it be heated in the presence of chlorine. Mercury(II)
chloride can also be prepared from other common mercury compounds in a single synthetic
step that can be accomplished using basic equipment and inexpensive reagents.
Elemental mercury can be obtained from mercury(II) chloride by either chemical or
electrochemical reduction of mercury(II) chloride and collecting the resulting liquid metal.
These processes can be accomplished using basic equipment and inexpensive reagents.
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Mercury(II) chloride can also be readily converted to other common inorganic mercury
compounds using basic equipment and inexpensive reagents which can then, in turn, be
converted to elemental mercury by heating.
Mercury(II) chloride is a stable solid. It sublimes at high temperatures facilitating its separation
and purification. It is used in a number of commercial applications and can be transported
using standard methods.
Mercury(II) chloride is a potential candidate for export as a mercury source because of its
following attributes:
It is commercially available;
It can be readily prepared from a wide variety of commercially available materials;
It can be transported easily;
It can be converted to elemental mercury simply by either chemical or electrochemical
methods; and
It can be used to produce elemental mercury by first converting it to other common
mercury compounds which are then heated.
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C.4 Mercury(II) iodide
Formula: Hgb
Percent mercury by weight: 44
CAS Index Name: Mercury iodide (HgI2)
CASRN: 7774-29-0
Synonyms: Mercuric iodide, Mercury diiodide, Mercury biniodide, Red Mercuric iodide,
Coccinite (Linstrom and Mallard, 2009)
C.4.1 Product Description
Mercury(II) iodide is either a red or yellow crystalline solid depending on its crystal structure.
The red iodide turns yellow on heating to 130ฐC, but returns to red on cooling. Mercury(II)
iodide has a melting point of 259ฐC and vaporizes without boiling at 354ฐC. Mercury(II) iodide
has a water solubility of 60 mg/L and is light sensitive (O'Neil et al., 2001).
Mercuric iodide is sold as a powder in 50 g and 250 g containers, as well as in solution as
Nessler's reagent (EPA Mercury Containing Products Database, 2008).
C.4.2 Product Uses
Mercury(II) iodide is reacted with potassium hydroxide or potassium iodide to form complex
halide K2Hgl4 (CAS No. 7783-33-7), which is known as either Mayer's reagent when in solid
form or as Nessler's reagent when in alkaline solution. This complex is used to detect low levels
of ammonia. The sodium complex (Na2HgI/i) can also be formed by reaction with sodium
hydroxide (Patnaik, 2003).
Mercury(II) iodide is used in instruments that detect nuclear particles. Various metals including
palladium, copper, aluminum, tin, silver, and tantalum affect the photoluminescence of
mercury(II) iodide, which is of importance in the preparation of high quality photodetectors
(Nowak and Singer, 1995).
Additional uses of mercury(II) iodide include that of an image enhancer in photography and
uses in medicine and veterinary medicine for the treatment of skin (HSDB, 2009). Mercury(II)
iodide has also been mentioned as a catalyst in group transfer polymerization of methacrylates
or acrylates (Nowak and Singer, 1995). It is not clear if these are current uses of mercury(II)
iodide.
C.4.3 Synthesis from mercury
Mercury (II) iodide is typically produced from the reaction of elemental mercury with iodine in
ethanol (Patnaik, 2003).
Mercury(II) iodide can also be prepared from other commonly available mercury compounds.
For example, mercury(II) iodide can be made by precipitation from a solution of a mercury(II)
salt and potassium iodide. Examples of mercury(II) salts used for this reaction are mercury(II)
chloride, mercury(II) nitrate, and mercury(II) acetate (Patnaik, 2003). Mercury(II) chloride,
nitrate, and acetate feedstocks for these processes can be obtained in commercial quantities, or
can themselves be readily prepared in one or two steps from elemental mercury and
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commercially available compounds. More information on the production of these compounds is
presented in their chemical summaries.
C.4.4 Reduction to elemental mercury
Mercury(II) iodide can be reduced to elemental mercury by first converting it to other mercury
compounds, which are then reduced to elemental mercury. For example, mercury(II) iodide is
converted to mercury(II) oxide by reaction with an alkali such as sodium, lithium, or potassium
hydroxide (CrossFire Gmelin Database, 2009). Mercury(II) oxide is reduced to elemental
mercury and oxygen when heated. More information on the reduction of mercury(II) oxide is
presented in its chemical summary.
C.4.5 Potential sources
Manufacturing and use facilities are potential sources of mercury(II) iodide as well as kits for
making Mayer's or Nessler's reagent.
C.4.6 Potential for export as an alternative to mercury
Mercury(II) iodide can be prepared directly from elemental mercury in a single step requiring
only that it be heated in the presence of iodine. Mercury(II) iodide can also be prepared from
other common mercury compounds in a single synthetic step that can be accomplished using
basic equipment and inexpensive reagents. Elemental mercury can be obtained from
mercury(II) iodide after chemical conversion to more readily reduced mercury(II) oxide. This
process can be accomplished using basic equipment. Mercury(II) iodide is a stable solid and is
used in a number of commercial applications. It is easy to handle and can be transported using
standard methods.
Mercury(II) iodide is a potential candidate for export as a mercury source because of its
following attributes:
It can be readily prepared from a wide variety of commercially available materials;
It can be transported easily; and
It produces elemental mercury first by chemical conversion to mercury(II) oxide,
followed by the heating and condensing of the resulting vapor.
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C.5 Mercury(II) nitrate
Formula: Hg(NO3)2
Percent mercury by weight: 62
CAS Index Name: Nitric acid, mercury(2+) salt (2:1)
CASRN: 10045-94-0
Synonyms: Mercuric nitrate, Mercury dinitrate, Mercury pernitrate (HSDB, 2009)
C.5.1 Product description
Mercury(II) nitrate is commonly found as the monohydrate, Hg(NOs)2*H2O. This compound is
a white crystalline or powdery substance with a melting point of 79ฐC (Lewis, 1997).
Mercury(II) nitrate decomposes on heating and is soluble in water and aqueous nitric acid.
Mercury(II) nitrate is insoluble in alcohol (Patnaik, 2003).
Mercury(II) nitrate is sold as a powder in various quantities, as well as in solution at 0.0141N,
0.0171N, 0.025N, and 0.2256N in 1.0 L or 500 ml volumes (EPA Mercury Containing Products
Database, 2008).
C.5.2 Product uses
Mercury(II) nitrate is used as the starting material and for the preparation of a great many other
mercuric products. It is a nitrating agent for aromatic organic compounds. It can also be used as
an analytical reagent for the determination of chloride ions in water (Nowak and Singer, 1995).
Mercury(II) nitrate was formerly used as an insecticide against Phylloxera (O'Neil et al., 2001). In
the late 1970's, the United States restricted the acceptable pesticide uses of mercury to the
treatment of outdoor textiles and to the control of fungal pests, particularly brown mold on
freshly sawn lumber, Dutch elm disease, and snow mold, eliminating this use for mercury(II)
nitrate.
Mercury(II) nitrate was formerly used to manufacture fur felt hats (O'Neil et al., 2001) before
this use was banned by the U.S. Public Health Service in 1941.
C.5.3 Synthesis from Mercury
Mercury(II) nitrate is typically prepared by dissolving elemental mercury in excess, hot,
concentrated nitric acid. Upon evaporation of the solution, large colorless deliquescent crystals
of the monohydrate, Hg(NO3)2 H2O, form (Patnaik, 2003).
Mercury(II) nitrate can also be obtained by boiling a solution of mercury(I) nitrate or by the
action of light on mercury (I) nitrate (Patnaik, 2003).
C.5.4 Reduction to elemental mercury
Gentle heating of mercury(II) nitrate generates mercury(II) oxide, evolving nitrogen dioxide and
oxygen. With strong heating, mercury(II) nitrate reduces to elemental mercury, nitrogen oxides,
and oxygen (Patnaik, 2003).
Mercury(II) nitrate can also be converted to other mercury compounds which can subsequently
be reduced to elemental mercury. For example, mercury(II) nitrate can be dissolved in water
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and treated with a strongly alkaline reagent, typically sodium hydroxide, to yield yellow
mercury(II) oxide. Mercury(II) oxide is reduced to elemental mercury and oxygen when heated.
More information on the reduction of mercury(II) oxide is presented in its chemical summary.
C.5.5 Potential sources
Potential sources of mercury(II) nitrate are the facilities where it is manufactured or used. Those
laboratories that use mercury(II) nitrate as an intermediate to form other mercury compounds
are likely to have the highest amounts of this compound present on-site.
Mercury(II)nitrate could be obtained through the disassembly or destruction of small-scale kits
designed to detect chlorine. However, this process would be labor intensive and only small
quantities are present within each kit.
C.5.6 Potential for export as an alternative to mercury
Mercury(II) nitrate is commercially available. Mercury(II) nitrate can be prepared directly from
elemental mercury in a single step requiring only that it be heated in the presence of nitric acid.
Elemental mercury can be obtained by strongly heating mercury(II) nitrate and condensing the
vapor. This process can be accomplished using basic equipment. Mercury(II) nitrate is a stable
solid and is used in a number of commercial applications. It is easy to handle and can be
transported using standard methods.
Mercury(II) nitrate is a potential candidate for export as a mercury source because of its
following attributes:
It is commercially available;
It can be readily prepared from a wide variety of commercially available materials;
It can be transported easily; and
It produces elemental mercury simply by heating and condensing the resulting vapor.
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C.6 Mercury(II) oxide
Formula: HgO
Percent mercury by weight: 93
CAS Index Name: Mercury oxide (HgO)
CASRN: 21908-53-2
Synonyms: Mercuric oxide, Mercuric oxide red, Mercuric oxide yellow (Linstrom and Mallard,
2009)
C.6.1 Product description
Mercury(II) oxide is a red/red-orange or yellow/orange-yellow powder. Red mercury(II) oxide
has a coarser particle size than yellow mercury(II) oxide. Mercury(II) oxide has a water
solubility of 58 mg/L (Weast, 1983-1984) and decomposes on exposure to light (O'Neil et al.,
2001). The decomposition temperature of mercury (II) oxide is 332ฐC (Nowak and Singer, 1995).
Mercury(II) oxide is sold in red or yellow powder, in quantities from 125 g to 50 kg (EPA
Mercury Containing Products Database, 2008).
C.6.2 Product uses
Mercury(II) oxide's primary uses are in batteries and as a reagent for the synthesis of other
mercury compounds, including Millon's base (Hg2NOH). Other uses include as a reagent for
analytical detection, as a chemical reagent in synthesis of organic compounds, as a depolarizer
in dry batteries, and as a catalyst in organic reactions. Former uses include use in antifouling
paints, as a seed protectant, and as a fungicide (HSDB, 2009). In the late 1970's, the United States
restricted the acceptable pesticide uses of mercury to the treatment of outdoor textiles and to
control of fungal pests, particularly brown mold on freshly sawn lumber, Dutch elm disease,
and snow mold. In 1972, the use of mercury in antifouling paint formulations was banned. In
1991, the EPA announced the cancellation of mercury biocide registrations (DeVito and Brooks,
2005) eliminating this use for mercury(II) oxide.
After the passage of the 1996 federal Mercury-Containing Battery Management Act, most
batteries made in the United States do not contain mercury. Mercury(II) oxide has been used as
the cathode material of dry cell batteries such as zinc-mercury, cadmium mercury, and indium-
bismuth-mercury cells. Mercury(II) oxide button cell batteries, once widely used in hearing
aids, are now prohibited under the Mercury-Containing Battery Management Act. The use of
larger mercury(II) oxide batteries is limited to the military and medical equipment where a
stable current and long service life is essential. Elemental mercury may be added to batteries,
including button cell batteries, in small quantities to prevent the buildup of hydrogen gas,
which can cause the cells to bulge and leak (U.S. EPA, 2009).
C.6.3 Synthesis from mercury
Mercury(II) oxide is typically prepared from other common mercury compounds. For example,
mercury(II) nitrate or mercury(II) chloride can be dissolved in water and treated with a strongly
alkaline reagent, typically sodium hydroxide, to yield yellow mercury(II) oxide or a mildly
alkaline reagent, such as sodium carbonate, to yield red mercury(II) oxide, which fall out of
solution. Red mercury(II) oxide is also prepared by heat-induced decomposition of mercury(II)
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nitrate (Nowak and Singer, 1995). Mercury(II) nitrate and mercury(II) chloride feedstocks for
these processes can be obtained in commercial quantities, or can themselves be readily prepared
in one or two steps from elemental mercury and commercially available compounds. More
information on the production of these compounds is presented in their chemical summaries.
Elemental mercury is stable to dry air, but is slowly converted to mercury(II) oxide in the
presence of moisture. The direct conversion of elemental mercury to mercury(II) oxide may be
accomplished more readily by heating mercury in air or oxygen at a temperature of about 350ฐC
(Patnaik, 2003).
Other direct conversions of mercury to mercury(II) oxide have been reported in the literature.
Mercury(II) oxide can be made by reacting elemental mercury with hydrogen peroxide or
aqueous hydrogen peroxide. It can also be made from reacting elemental mercury with
potassium hydroxide in water or from the reaction of mercury with carbon dioxide.
Additionally, mercury(II) oxide can be made from reacting elemental mercury with potassium
chlorate (CrossFire Gmelin Database, 2009). It is unclear if these latter methods are useful for
producing large quantities of mercury(II) oxide.
C.6.4 Reduction to elemental mercury
Mercury(II) oxide decomposes on exposure to light or when heated to temperatures above
500ฐC, releasing elemental mercury and oxygen (O'Neil et al., 2001).
Elemental mercury can also be recovered from mercury(II) oxide electrolytically using an
electrolyte solution comprised of glacial acetic acid and water (Grossman and George, 1991,
1989).
C.6.5 Potential sources
Potential sources of mercury(II) oxide are from the facilities where it is manufactured or used.
Those laboratories that use mercury(II) oxide as an intermediate to form other mercury
compounds are likely to have the highest amounts of this compound present on-site.
Another potential source of mercury(II) oxide is from large mercury oxide batteries. U.S. federal
law allows mercury oxide batteries to be sold only if the manufacturer has established a system
to collect the waste batteries and ensure that the mercury is properly managed. The recycling of
mercury from waste mercury oxide batteries involves the breaking and crushing of the batteries
followed by the thermal conversion of mercury(II) oxide to elemental mercury and the
condensation and collection of the liquid metal (Martin et al., 2004).
The use and disposal of button cell batteries containing metallic mercury are unregulated at the
federal level (U.S. EPA, 2009c). However, the use of mercury(II) oxide in button cell batteries is
prohibited under the Mercury-Containing Battery Management Act of 1996.
C.6.6 Potential for export as an alternative to mercury
Mercury(II) oxide is commercially available. It can be prepared directly from elemental mercury
in a single step requiring only that it be heated in the presence of air. Mercury(II) oxide can also
be prepared from other common mercury compounds in a single synthetic step that can be
accomplished using basic equipment and inexpensive reagents. Elemental mercury can be
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obtained by heating mercury(II) oxide and condensing the vapor. This process can be
accomplished using basic equipment. Mercury(II) oxide is a stable solid and is used in a number
of commercial applications. It is easy to handle and can be transported using standard methods.
Mercury(II) oxide is a potential candidate for export as a mercury source because of its
following attributes:
It is commercially available;
It can be readily prepared from a wide variety of commercially available materials;
It can be transported easily; and
It produces elemental mercury simply by heating and condensing the resulting vapor.
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C.7 Mercury(II) selenide
Formula: HgSe
Percent mercury by weight: 72
CAS Index Name: Mercury selenide (HgSe)
CASRN: 20601-83-6
Synonyms: Mercury-selenium complex, Mercuric selenide, Mercury monoselenide
(ChemlDplus Database, 2009), Tiemannite (Simon et al, 2006)
C.7.1 Product description
Mercury(II) selenide is a solid that takes the form of grey or violet-black plates, melting point >
600 ฐC. Mercury(II) selenide is insoluble in water and will sublime in a vacuum (Weast, 1983-
1984).
C.7.2 Product uses
Mercury(II) selenide has seen only limited use in commerce. Mercury(II) selenide is used as a
semiconductor in solar cells, thin-film transistors, infrared detectors, and ultrasonic amplifiers
(Lewis, 1997).
C.7.3 Synthesis from mercury
Mercury(II) selenide is prepared directly from its elements, mercury and selenium, to give a
violet-black material (Bebout, 2006). This reaction forms the basis for gas purification systems
controlling the emission of elemental mercury from the burning of coal and natural gas. In these
systems, selenium is used as an absorbent for mercury, forming stable mercury(II) selenide
(Simon et al., 2006).
C.7.4 Reduction to elemental mercury
Mercury(II) selenide can be retorted to release its elemental constituents, mercury and selenium.
For example, mercury(II) selenide waste from refining ores, such as zinc and gold, is a slurry
that has been reprocessed in a multiple-hearth furnace that evaporates the mercury fraction.
Alternatively, this residue can be converted to metallic mercury in a rotary kiln by adding lime
fluxes, with a relatively inert residue remaining behind (Simon et al., 2006).
Liquid treatment processes (hydrometallurgy) for mercury(II) selenide that result in the
mercury being extracted in the form of mercury(II) oxide or mercury(II) sulfide have been
reported. However, these processes do not appear to be economically practical at present
because of the relative expense of the reactants involved (Simon et al., 2006).
C.7.5 Potential sources
Mercury(II) selenide may be a waste from the refining or smelting of ores, including zinc and
gold, when the ore contains both mercury and selenium, or mercury-containing sulfidic ores
(Simon et al., 2006). Mercury(II) selenide is also a byproduct from flue gases purification
processes in which selenium is used as an absorbent to remove volatilized mercury from the
burning of fuels such as coal and natural gas (Simon et al., 2006).
C.7.6 Potential for export as an alternative to mercury
Mercury(II) selenide can be a waste from the refining of ores, such as zinc and gold. Mercury(II)
selenide may also be present in waste streams from the burning of coal and natural gas where
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selenium is used as an absorbent for mercury. Mercury(II) selenide can be prepared directly
from elemental mercury in a single step by reaction with selenium. This process can be
accomplished using basic equipment but requires relatively expensive selenium as a feedstock.
Elemental mercury can be obtained by heating mercury(II) selenide and condensing the vapor.
This process can be accomplished using basic equipment. Mercury(II) selenide is a stable solid
and is used in a number of commercial applications. It is easy to handle and can be transported
using standard methods.
Mercury(II) selenide is an unlikely candidate for export as a mercury source because of its
following attributes:
Its synthesis requires relatively expensive selenium;
It likely has a higher monetary value as mercury(II) selenide than as elemental mercury;
and
Processes to recover mercury may produce toxic hydrogen selenide [ftSe] gas.
The above factors are anticipated to far outweigh the following attributes which suggest that
mercury(II) selenide could be a possible candidate for export as a mercury source because:
It is available from waste streams from various industrial processes; and
It produces elemental mercury simply by retorting and condensing the resulting vapor.
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C.8 Mercury(II) sulfate
Formula: HgSC>4
Percent mercury by weight: 68
CAS Index Name: Sulfuric acid, mercury(2+) salt (1:1)
CASRN: 7783-35-9
Synonyms: Mercuric sulfate, Mercury bisulfate, Mercury persulfate (HSDB, 2009)
C.8.1 Product description
Mercury(II) sulfate forms white crystals that will absorb water from the air if not kept in a
sealed container. It is soluble in hot, dilute sulfuric acid, hydrochloric acid, and concentrated
solutions of sodium chloride. Decomposes before reaching 450ฐC. When dissolved in water,
mercury(II) sulfate will decompose to form the water-insoluble basic sulfate HgSCv2HgO
(Patnaik, 2003).
C.8.2 Product uses
Mercury(II) sulfate is used with sodium chloride in the extraction of gold and silver from
roasted pyrites. It is also a reagent for wine coloring (Patnaik, 2003). Mercury(II) sulfate is used
in analytical chemistry to bind chloride ions in the determination of the COD of wastewater and
as a catalyst in organic reactions such as conversion of acetylene to acetaldehyde. Mercury(II)
sulfate can be used as a depolarizer in galvanic cells (Simon et al., 2006). The 1996 U.S. Mercury-
Containing Battery Management Act limited the use of mercury in batteries to mercury oxide
batteries and small quantities of elemental mercury added to batteries to prevent the buildup of
hydrogen gas.
C.8.3 Synthesis from mercury
Mercury(II) sulfate is typically prepared by heating mercury with an excess of concentrated
sulfuric acid (Patnaik, 2003). Mercury(II) sulfate is also prepared by reaction of a freshly
prepared and washed wet filter cake of yellow mercury(II) oxide with sulfuric acid in glass or
glass-lined vessels (DeVito and Brooks, 2005). Mercury(II) oxide feedstock for this process can
be obtained in commercial quantities, or can itself be readily prepared in one or two steps from
elemental mercury and commercially available compounds. More information on the
production of mercury(II) oxide is presented in its chemical summary.
C.8.4 Reduction to elemental mercury
Mercury(II) sulfate first turns yellow and then becomes red-brown when heated. When heated
to red heat, it will reduce to elemental mercury, sulfur dioxide, and oxygen (Patnaik, 2003).
C.8.5 Potential sources
Potential sources of mercury(II) sulfate are from the facilities where it is manufactured or used
in commercial processes. Mining facilities represent potential sources of this compound because
of the use of mercury(II) sulfate in the extraction of gold and silver.
Industries that use mercury(II) sulfate to capture mercury as part of their waste control
procedures represent an indirect source of this material and may have the most significant
amounts of this compound present on-site. For example, smelter gas containing volatilized
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mercury can be passed through heated, concentrated sulfuric acid to produce mercury(II)
sulfate, which precipitates out when the solution becomes saturated in the Outokumpu process
(Louie, 2005).
C.8.6 Potential for export as an alternative to mercury
Mercury(II) sulfate is commercially available. It is also present in waste streams from industries
that use the Outokumpu process to cleanse mercury from flue gases. Mercury(II) sulfate can be
prepared directly from elemental mercury in a single step requiring only that it be heated in the
presence of concentrated sulfuric acid. Mercury(II) sulfate can also be prepared from other
common mercury compounds in a single synthetic step that can be accomplished using basic
equipment and inexpensive reagents. Elemental mercury can be obtained by heating
mercury(II) sulfate and condensing the vapor. This process can be accomplished using basic
equipment. Mercury(II) sulfate is a stable solid and is used in a number of commercial
applications. It is easy to handle and can be transported using standard methods.
Mercury(II) sulfate is a potential candidate for export as a mercury source because of its
following attributes:
It is commercially available;
It can be found in waste streams from mercury treatment processes;
It can be readily prepared from a wide variety of commercially available materials;
It can be transported easily; and
It produces elemental mercury simply by heating and condensing the resulting vapor.
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C.9 Mercury(II) sulfide
Formula: HgS
Percent mercury by weight: 86
CAS Index Name: Mercury sulfide (HgS)
CASRN: 1344-48-5
Synonyms: Cinnabar, Metacinnabar, Mercury sulfide black, Mercury Sulfide red, Chinese red,
Vermilion (Lewis, 1997)
C.9.1 Product description
Mercury(II) sulfide is a red or black solid depending on its crystal structure. Red mercury(II)
sulfide occurs in nature as the mineral cinnabar, which is the principle source for mercury
production worldwide. Black mercury(II) sulfide, known as metacinnabar, occurs only rarely in
nature. It sometimes coexists with the red form and may be found as a black deposit over
cinnabar (Patnaik, 2003). The red sulfide transitions to the black sulfide at 386ฐC, but reverts
back to red form on cooling. Both forms are insoluble in water and will sublime at 583ฐC. Red
mercury(II) sulfide is light sensitive (O'Neil et al, 2001).
C.9.2 Product uses
The most important use of this compound, the principal ore of mercury, is for the extraction of
mercury metal. It was also used as an artificially prepared scarlet product, vermilion, which
was used as artists' pigment and for coloring plastics. The red sulfide is also used as an
antibacterial agent. The black sulfide is used for coloring horns, rubber, and other materials
(Patnaik, 2003). Production of mercury-containing pigments in the United States was
discontinued in 1988, but some mercury pigments may still be imported into the United States
(DeVito and Brooks, 2005).
C.9.3 Synthesis from mercury
Red mercury(II) sulfide occurs natively and is mined in the form of the mineral cinnabar. It can
also be prepared by heating elemental mercury with a solution of potassium pentasulfide,
producing a scarlet compound. For use as the pigment vermilion, mercury(II) sulfide may be
made by grinding sodium sulfide with sulfur and slowly adding mercury. The shades are not as
bright when prepared at 0ฐC (Patnaik, 2003).
Black mercury(II) sulfide is prepared by treating mercury with molten or powdered sulfur
(Patnaik, 2003). Black mercury(II) sulfide is also prepared from other common mercury
compounds. For example, black mercury(II) sulfide can be made by precipitation from an
aqueous solution of mercury(II) salt, such as mercury(II) chloride, with excess hydrogen sulfide
or sodium sulfide (Patnaik, 2003). The mercury(II) chloride feedstock for this process can be
obtained in commercial quantities, or can itself be readily prepared in one or two steps from
elemental mercury and commercially available compounds. More information on the
production of mercury(II) chloride is presented in its chemical summary.
C.9.4 Reduction to elemental mercury
The methods used to recover elemental mercury from mercury(II) sulfide(cinnabar ore) may
also be applied to synthetic mercury(II) sulfide. A typical process is heating or retorting
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mercury(II) sulfide in a current of air or oxygen. The reduction reaction begins at about 300ฐC to
release mercury vapor and sulfur dioxide. Alterations to the typical process include the
addition of reducing metals or fluxes such as iron metal or lime (calcium oxide) so as to bind the
sulfur in solid form (as iron sulfide or calcium sulfate). The liberated elemental mercury vapor
is condensed and collected (Patnaik, 2003).
C.9.5 Potential sources
Potential sources of mercury(II) sulfide are from facilities where it is manufactured or used.
Although there are currently no active cinnabar mines in the United States, mercury(II) sulfide
can be found in waste dumps from abandoned mercury mines (Hojdova et al., 2008).
Industries that use mercury(II) sulfide as part of their waste treatment procedures, and
industries that process these wastes, are likely to have significant amounts of this compound
present on-site. An example of waste treatment processes that may form mercury(II) sulfide on-
site include the treatment of aqueous waste streams from processing of petroleum or from the
chlor-alkali process with excess sodium sulfide. The resulting water-insoluble mercury(II)
sulfide precipitates out and is collected and sent for mercury recovery. Another example is the
removal of mercury present in natural gas by the use of activated charcoal scrubbers
impregnated with sulfur (Simon et al., 2006). Once saturated with mercury(II) sulfide, the used
charcoal filter can be retorted, regenerating the charcoal and liberating elemental mercury
(DeVito and Brooks, 2005).
C.9.6 Potential for export as an alternative to mercury
The naturally occurring form of mercury(II) sulfide, mercury(II) sulfide(cinnabar ore), is the
world's principal source of mercury. Mercury(II) sulfide is also a byproduct of mercury waste
treatment processes that take advantage of mercury's natural affinity for sulfur. Mercury(II)
sulfide can be prepared directly from elemental mercury in a single step requiring only that it
be heated in the presence of sulfur. Mercury(II) sulfide can also be prepared from other
common mercury compounds in a single synthetic step that can be accomplished using basic
equipment and inexpensive reagents. Elemental mercury can be obtained by heating
mercury(II) sulfide and condensing the vapor. This process can be accomplished using basic
equipment. Mercury(II) sulfide is a stable solid and is used in a number of commercial
applications. It is easy to handle and can be transported using standard methods.
Mercury(II) sulfide is a potential candidate for export as a mercury source because of its
following attributes:
It is commercially available;
It has alternative sources as it may be found in waste streams from a wide variety of
mercury treatment processes;
It can be readily prepared from a wide variety of commercially available materials;
It can be transported easily; and
It produces elemental mercury simply by heating and condensing the resulting vapor.
It is unlikely that mercury(II) sulfide(cinnabar ore) would be exported because there are no
active mines in the United States Due to the costs associated with making purified vermilion, it
is also unlikely that mercury(II) sulfide pigments would be used as a source for elemental
mercury.
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C.10 Mercury(II) thiocyanate
Formula: Hg(SCN)2
Percent mercury by weight: 63
CAS Index Name: Thiocyanic acid, mercury(2+) salt (2:1)
CASRN: 592-85-8
Synonyms: Mercuric thiocyanate, Mercuric sulfocyanate, Mercury (HSDB, 2009)
C.10.1 Product description
Mercury(II) thiocyanate is a white powder that is thermally unstable. Decomposition begins at
110ฐC and becomes spontaneous at 165ฐQ with the compound increasing in volume and
producing a blue flame (Simon et al., 2006).
Mercury(II) thiocyanate has a water solubility of 0.7 g/L at 20ฐQ but will decompose in hot
water (Weast, 1983-1984). Mercury(II) thiocyanate is light sensitive (O'Neil et al., 2001).
Mercury(II) thiocyanate is sold as a powder in quantities from 25 g to 5 kg, and in a 1.0 g/L
methanol solution (EPA Mercury Containing Products Database, 2008).
C.10.2 Product uses
Mercury(II) thiocyanate is used as an analytical reagent for chloride analysis of water and as an
intensifier in photography (HSDB, 2009). Mercury(II) thiocyanate has been used in pyrotechnics
in the manufacture of "pharaoh's serpent" fireworks (O'Neil et al., 2001). Mercury salts are
currently prohibited in consumer fireworks in the United States by Federal law (CPSC, 1997).
C.10.3 Synthesis from mercury
Mercury(II) thiocyanate is typically produced from other common mercury compounds.
Mercury(II) thiocyanate is made as a white precipitate by the addition of potassium thiocyanate
solution to mercury(II) nitrate (Patnaik, 2003). Another method is to add ammonium
sulfocyanate to a solution of mercury(II) nitrate, yielding mercury(II) thiocyanate as a
precipitate (Lewis, 1997). Mercury(II) nitrate feedstock for these reactions can be obtained in
commercial quantities, or can itself be readily prepared in one or two steps from elemental
mercury and commercially available compounds. More information on the production of
mercury(II) nitrate is presented in its chemical summary.
C.10.4 Reduction to elemental mercury
Mercury(II) thiocyanate swells up to many times its original volume when it is heated,
decomposing finally at about 165ฐC into elemental mercury, nitrogen, and oxides of carbon and
sulfur (O'Neil et al., 2001).
C.10.5 Potential sources
Mercury(II) thiocyanate can be acquired in small amounts from kits used to analyze for chlorine
in water and from photography supplies. Mercury(II) thiocyanate is also a component of
"pharaoh's serpent" type fireworks, although they have been prohibited in the United States
(CPSC, 1997).
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C.10.6 Potential for export as an alternative to mercury
Mercury(II) thiocyanate can be prepared from other common mercury compounds in a single
synthetic step that can be accomplished using basic equipment and inexpensive reagents.
Elemental mercury can be obtained by heating mercury(II) thiocyanate, though this reaction is
exothermic and expands many times in volume making it difficult to control using basic
equipment. Mercury(II) thiocyanate has a few current commercial applications where it is
present in small quantities. Mercury(II) thiocyanate is an unstable solid, yet it only carries a
DOT Hazard Label of 6.1: Irritating material which, upon contact with fire or air, gives off
dangerous or intensely irritating fumes (U.S. DOT, 2009).
Mercury(II) thiocyanate is an unlikely candidate for export as a mercury source because of its
following attributes:
It is an unstable solid; and
It produces elemental mercury in a manner that is difficult to control using basic
equipment.
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C.ll Phenyl mercury(II) acetate
Formula: Hg(C6H5)(C2H3O2)
Percent mercury by weight: 60
CAS Index Name: Mercury, (acetato-KO)phenyl-
CASRN: 62-38-4
Synonyms: Phenylmercuric acetate, Acetoxyphenylmercury, PMA (HSDB, 2009)
C.ll.l Product description
Phenylmercury acetate forms small white lustrous crystals that melt at 148-150ฐC. It is only
slightly soluble in water, but dissolves in glacial acetic acid and in various organic solvents.
Phenylmercury acetate is slightly volatile at ordinary temperatures (Lewis, 1997).
C.11.2 Product uses
Phenylmercury acetate is used as a preservative in ophthalmological preparations and nasal
sprays at concentrations around 0.0008 and 0.002%, respectively (U.S. FDA, 2009a).
Phenylmercuric acetate is also used as the starting material in the preparation of many other
phenylmercury compounds (Nowak and Singer, 1995). Many phenylmercury compounds are
used as catalysts in the manufacturing of polyurethanes (Foulkes, 2001).
Phenylmercury compounds were also formerly employed as slimicides for seed dressing, as
fungicides in paper and pulp, and as topical disinfectants and spermicides (Foulkes, 2001). In
the late 1970's, the United States restricted the acceptable pesticide uses of mercury to the
treatment of outdoor textiles and to control of fungal pests, particularly brown mold on freshly
sawn lumber, Dutch elm disease, and snow mold (DeVito and Brooks, 2005), thereby limiting
many of the uses of phenyl mercury(II) acetate.
Mercury-based biocides, such as phenylmercury acetate and phenylmercury oleate, were
formerly registered as biocides in interior and exterior paints, and in antifouling paints. In 1972,
the use of mercury in antifouling paint formulations was banned. In 1991, the EPA announced
the cancellation of mercury biocide registrations (DeVito and Brooks, 2005).
C.11.3 Synthesis from mercury
Phenylmercury(II) acetate is synthesized from other mercury compounds. Mercury(II) acetate is
reacted with benzene to form phenylmercury(II) acetate (Foulkes, 2001). Mercury(II) acetate
feedstock for this process can be obtained in commercial quantities, or can itself be readily
prepared in one or two steps from elemental mercury and commercially available compounds.
More information on the production of mercury(II) acetate is presented in its chemical
summary.
C.11.4 Reduction to elemental mercury
Organomercury compounds, such as phenylmercury acetate, are not as easily converted to
elemental mercury as inorganic mercury compounds. One method used on waste streams
containing organomercury compounds is to convert them to inorganic mercury compounds by
treatment with chlorine. The inorganic mercury compounds thus formed can be reduced with
sodium borohydride to liberate elemental mercury. This process is known as the Ventron
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process (Nowak and Singer, 1995) and was tested on phenylmercury acetate in U.S. Patent No.
3,764,528 by Ventron Corporation in 1973.
Another possible route to elemental mercury from phenylmercury(II) acetate is by burning to
oxidize off the carbon followed by collecting the resulting vapor.
C.11.5 Potential sources
Manufacturing and use sites are potential sources of phenylmercury(II) acetate. To limit
phenylmercury(II) acetate waste, it is often precipitated from its solution in acetic acid by
addition of water. The filtrate is then collected and reused (Nowak and Singer, 1995).
Ophthalmological preparations and nasal sprays are possible sources of phenylmercury(II)
acetate, although it is present in extremely low concentrations in these products.
C.11.6 Potential for export as an alternative to mercury
Phenylmercury(II) acetate can be prepared from other common mercury compounds in a single
synthetic step that can be accomplished using basic equipment and inexpensive reagents.
Elemental mercury can be obtained by converting phenylmercury(II) acetate to mercury(II)
chloride, then either chemical or electrochemical reduction of the chloride, followed by
collection of the resulting liquid metal. It is possible that elemental mercury may be obtained by
burning phenylmercury(II) acetate to oxidize off the carbon and collecting the resulting vapor.
These processes can be accomplished using basic equipment and inexpensive reagents
Phenylmercury(II) acetate is a stable solid and is used in a number of commercial applications.
It is easy to handle and can be transported using standard methods.
Phenylmercury(II) acetate is a possible candidate for export as a mercury source because of its
following attributes:
It can be prepared from commercially available materials;
It can be transported easily; and
It may produce elemental mercury by burning and condensing the resulting vapor.
However, phenylmercury(II) acetate is far less attractive as a candidate for export as a mercury
source because it would require an additional step to make and export phenylmercury(II)
acetate than to export feedstock mercury(II) acetate directly. Given that mercury(II) acetate is a
better source of elemental mercury, its conversion to phenylmercury(II) acetate is
counterproductive.
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C.12 Thimerosal
Formula: Hg
Percent mercury by weight: 50
CAS Index Name: Mercurate(l-)/ ethyl[2-(mercapto-KS)benzoato(2-)-KO]-/ sodium (1:1)
CASRN: 54-64-8
Synonyms: Thiomersal, Sodium ethylmercurithiosalicylate, Merthiolate (HSDB, 2009)
C.12.1 Product description
Thimerosal is a cream-colored crystalline powder with a water solubility of about 1.0 g/mL. It is
stable in air, but is light sensitive (O'Neil et al., 2001). Melting point = 232 - 233ฐC and pH = 6.7
for a 1% w/v aqueous solution at 20ฐC.
C.12.2 Product uses
Thimerosal is primarily used as a preservative in pharmaceutical applications, such as
ophthalmic solutions and vaccines (U.S. FDA, 2009a). Thimerosal is also used as an
antimicrobial preservative in cosmetics (HSDB, 2009). Thimerosal is an organic mercury
compound that is metabolized to ethylmercury and thiosalicylate. It has been primarily
used as a preservative in pharmaceutical applications, such as ophthalmic solutions and
vaccines (U.S. FDA, 2009a).
Thimerosal has been used as a preservative in biological products since the 1930s. Apart from
some narrow regulatory exceptions (such as for some live vaccines), preservatives are required
to be added to multi-dose vials of vaccines in the United States to prevent microbial growth.
Thimerosal is no longer included, or has been reduced to trace amounts, in all vaccines
routinely recommended for children 6 years and under, except in some formulations of the
inactivated influenza vaccine (U.S. FDA, 2009b). This has been possible because the vaccines
are formulated in single-dose presentations. Inactivated influenza vaccine is available in both
thimerosal-preservative-containing and thimerosal-preservative-free formulations.
Thimerosal in concentrations of 0.001-0.01% are effective against a broad spectrum of
pathogens; a vaccine containing 0.01% thimerosal contains 50 micrograms of thimerosal per
0.5 mL dose, or approximately 25 micrograms of mercury per 0.5 mL dose (U.S. FDA, 2009a).
In June 2000, the American Academy of Family Physicians (AAFP), the American Academy of
Pediatrics (AAP), the Advisory Committee on Immunization Practices (ACIP), and the Public
Health Service (PHS) released a joint statement recommending moving rapidly to vaccines free
of thimerosal. They declared the use of thimerosal as a preservative acceptable until adequate
supplies of thimerosal-free vaccines are available (Toxnet Hazardous Substances Database,
2008h). According to the FDA, the use of mercury-containing preservatives in vaccines has
declined since 1999, primarily due to manufacturers transitioning from multi-dose vials which
require a preservative to single-dose vials U.S. Food and Drug Administration, 2008).
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C.12.3 Synthesis from mercury
Thimerosal is made by the reaction between ethyl mercuric chloride and thiosalicylic acid in
alcoholic sodium hydroxide (Lewis, 1997). Ethyl mercuric chloride can be made from the
reaction of mercury(II) chloride and an organometallic reagent such as tetraethyl lead or triethyl
aluminum (Crossfire Gmelin Database, 2009). Mercury(II) chloride feedstock for this process
can be obtained in commercial quantities, or can itself be readily prepared in one or two steps
from elemental mercury and commercially available compounds. More information on the
production of mercury(II) chloride is presented in its chemical summary.
C.12.4 Reduction to elemental mercury
Organomercury compounds are not as easily converted to elemental mercury as inorganic
mercury compounds. One method used on waste streams containing organomercury
compounds is to convert them to inorganic mercury compounds by treatment with chlorine.
The inorganic mercury compounds thus formed can be reduced with sodium borohydride to
liberate elemental mercury. This process is known as the Ventron process (Nowak and Singer,
1995).
It is possible that elemental mercury may be obtained by burning thimerosal to oxidize off the
carbon and collecting the resulting mercury vapor.
C.12.5 Potential sources
Manufacturing and use sites are potential sources of this compound. Vaccines and
ophthalmological preparations are possible sources of thimerosal as well, although it is present
in extremely low concentrations in these products.
C.12.6 Potential for export as an alternative to mercury
Thimerosal can be prepared from elemental mercury in multiple steps, which require expensive
reagents and specialized equipment. Elemental mercury can be obtained by converting
thimerosal to mercury(II) chloride, then either chemical or electrochemical reduction of the
chloride, followed by collection of the resulting liquid metal. It is possible that elemental
mercury may be obtained by burning thimerosal to oxidize off the carbon and collecting the
resulting mercury vapor. Thimerosal is a light sensitive solid and would require careful
transport.
Thimerosal is an unlikely candidate for export as a mercury source because of its following
attributes:
It is difficult to prepare and requires expensive reagents and specialized equipment;
It is light sensitive and requires careful transport; and
It has a higher monetary value than elemental mercury.
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Appendix D - Detailed Chemistry of Mercury Compounds
D.I Conversion of elemental mercury to mercury compounds
Elemental mercury can be easily converted in one or two steps to a variety of inorganic and
organometallic mercury compounds using inexpensive, readily available materials (Simon et
al., 2006; Patnaik, 2003; Nowak and Singer, 1995). The following examples illustrate some
common reactions of elemental mercury. The compounds shown in these examples are
representative of those currently used and/or generated in large scale processes in the
manufacturing, mining, power generation, and petroleum industries, or other commercial
processes.
D.I.I The chemical transformation of elemental mercury into mercury(II) sulfide
Elemental mercury can be converted to mercury(II) sulfide by reaction with molten sulfur, or
with polysulfide salts, such as potassium pentasulfide. The reaction between mercury and
potassium pentasulfide is used to produce pigment grade vermilion (red mercury(II) sulfide).
Hg + S - HgS
heat
Hg + K2S5 - HgS + K2S4
heat
D.1.2 The chemical transformation of mining byproducts into mercury(II) sulfide
The Merrill-Crowe process is the reaction of polysulfide or dithiocarbamate salts with soluble
mercury-containing waste in gold mining cyanide leachate streams which makes insoluble,
isolable mercury sulfide compounds.
Hg + CN- [Hg(CN)4]2-
[Hg(CN)4]2- + S2- ^ HgS + 4CN-
D.1.3 The chemical reaction of elemental mercury with acids to form mercury nitrates and
sulfates
Mercury will react with concentrated nitric and sulfuric acids to produce mercury(II) nitrates
and sulfates, respectively.
Hg + 4HNO3 ^ Hg(NO3)2 + 2 NO2 + 2 H2O
Hg + 2 H2SO4 *- Hg(SO4) + SO2 + 2 H2O
Mercury(I) nitrate is a known compound, but is difficult to purify. Its manufacture from hot,
dilute nitric acid produces an impure grade of mercury(I) nitrate that is contaminated with the
mercury(II) species (Nowak and Singer, 1995). Mercury(I) sulfate can be prepared by the
electrochemical oxidation of mercury in dilute sulfuric acid (Simon et al., 2006).
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D.1.4 The chemical oxidation of elemental mercury in acetic acid to form mercury(II) acetate
The preparation of mercury(II) acetate is accomplished by reacting elemental mercury with
peracetic acid dissolved in acetic acid. However, peracetic acid requires careful handling and
the reaction between mercury and peracetic acid is difficult to control. Alternatively,
mercury(II) acetate may be made by reacting mercury and hydrogen peroxide in concentrated
acetic acid (Nowak and Singer, 1995).
O O
Hg + HOOH + 2 CH3COOH * H3C O Hg O CH3
D.2 Reactivity of mercury compounds
Other examples include the preparation of mercury(I) sulfate from mercury(I) nitrate and the
preparation of mercury(II) acetate from mercury(II) oxide.
Hg2(NO3)2 + Na2SO4 ^ Hg2SO4 + 2NaNO3
O O
HgO + 2 CH3COOH (dilute) *- H3C/^O Hg O CH3
The facile conversion of water-soluble mercury compounds to insoluble materials is often used
mercury control technology. For example, soluble mercury compounds can be converted to
mercury(II) sulfide for waste remediation.
HgCl2 (soluble) + Na2S ป HgS (insoluble) + 2 NaCl
D.3 Conversion of Mercury Compounds to Elemental Mercury
Mercury compounds can be readily converted to elemental mercury using techniques that
range from the simple to the complex. The three processes commonly used to accomplish this
transformation in order of increasing sophistication are thermal decomposition, chemical
reduction, and electrochemical reduction.
D.3.1 Thermal Decomposition
Mercury compounds that are particularly amenable to retorting include mercury(II) oxide,
mercury(II) sulfide, mercury(II) selenide, and mercury(II) nitrate.
HgO *- Hg + 1/2 O2
heat
HgS + 02 - Hg + S02
heat
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Solid media such as soil or sludge containing mercury and mercury compounds may also be
decontaminated by retorting.
A notable exception to common mercury compounds susceptible to thermal decomposition is
mercury(II) chloride. This compound volatilizes before the decomposition temperature can be
reached. Therefore, mercury(II) chloride cannot be converted to elemental mercury in open
vessels. Export of mercury(II) chloride for conversion to elemental mercury by methods other
than retorting would be expected to require additional chemical processing and facilities, albeit
still inexpensively performed.
D.3.2 Electrochemical reduction
Elemental mercury is regenerated from spent scrubber solutions used in the Boliden-Norzink
process by electrowinning. The spent scrubber solution, which contains mercury(I) and
mercury(II) chlorides, is treated with chlorine gas to convert all of the mercury species to
mercury(II) chloride. The mercury(II) chloride is reduced at a cathode made of elemental
mercury in a specially-designed electrochemical cell (Louie, 2005).
cathode: Hg2+ + 2 e- *- Hg
anode: 2 Cl- ป- C12 + 2 e-
overall: HgCl2 * Hg + C12
Grossman and George (1991,1989) report processes for the electrochemical reduction of
mercury(I) chloride and mercury(II) oxide. The cell for the reduction of mercury(I) chloride
employs a platinum anode and a cathode made of copper, nickel, or a nickel/iron alloy.
Mercury(I) chloride is suspended in an aqueous solution of hydrochloric acid, and a current is
applied to the cell. Elemental mercury is formed at the cathode at 25ฐC. The process for
reducing mercury(II) oxide is similar and uses an aqueous solution of acetic acid as the
electrolyte.
An electrolytic waste treatment method has been reported for the remediation of acidic,
alkaline, or organic waste streams containing mercury compounds. Mercury(I) chloride is
reduced in a cell in which the anode and cathode are made from tin, silver, or copper alloyed
with gold, zinc, iron, gallium, aluminum, or sodium. As it is produced, mercury forms an
amalgam with the cathode material. The amalgam may then be collected for the liberation of
pure mercury (Pitton, 1994).
D.4 Organomercury compounds
Most organomercury compounds have limited use in commerce, are highly toxic and are not
likely to be suitable for export. Organomercury(I) compounds are not stable and can be
prepared only at low temperatures. Although organomercury(II) compounds are relatively
stable to air and moisture, some of the reagents used to prepare them, such as
organomagnesium reagents (known as Grignard reagents), are moisture sensitive and the
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reactions must be carried out in dry solvents under an inert atmosphere, greatly complicating
these processes. Certain organomercury compounds have seen recent use as pesticides,
preservatives, and pharmaceuticals. Reactions used to prepare some representative
organomercury compounds are shown here.
D.4.1 Phenylmercury(II) carboxylates
Phenylmercury(II) carboxylates were once used as preservatives in paints. The two most
common were phenylmercury(II) acetate and phenylmercury(II) oleate. The actetate is prepared
from mercury(II) acetate and benzene.
o o
H3C 0-Hg-O CH3 X^/ H3C 0-Hg^\ /> H3
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