### Draft Final Report to U.S. Environmental Protection Agency Region IX



# Mercury and Modern Gold Mining in
Nevada

Greg Jones
Glenn Miller

Dept. of Natural Resources and Environmental Sciences Mail Stop 199 University of Nevada Reno, NV 89557 gcmiller@unr.edu
775-784-4108

March 31, 20052 A. Introduction Mercury has long been associated with prec ious metals mining, and releases into the environment remain a concern, due to the hea lth effects of mercury on humans and other organisms. Much of the histor ic release of mercury has been associated with either primary mercury mining, or use of that mercury for reco very of gold and silver via amalgamation for extraction of these precious metals from processed ore. For example, amalgamation processes were the primary source of mercur y releases to the Carson River Superfund Site during the late 1800’s, and occu rred via tailings disposal, thermal processes, and other discharges to surface water, land and the at mosphere. In the United States, mercury amalgamation for precious metals recovery ha s effectively ceased, and introduction of new mercury from hard rock mining activities is prim arily associated with inadvertent release of mercury during precious metals mining and proce ssing. In recent years, all of the primary mercury mines in the U.S. have been clos ed, and the only significant source of new anthropogenic mercury into commerce is bypr oduct production, again, primarily from the precious metals mining industry. In 2003, approximately 82% of gold produced in the U.S. came from Nevada mines (Nevada Bureau of Mines and Geology, 2003). Based on a review of the available information, the large majority of new byproduct mercury is also produced in Nevada. This report assesses how mercury is managed in precious metals mines in Nevada.

B. Objectives and Purpose of Report Because of concerns about production and re lease of mercury into the environment, information is required to determine the sour ces of mercury from precious metals mining and how these are managed. We sought to answer the following questions:

(1) What is the total amount of by-product me rcury produced annually in Nevada gold mining facilities? How is this mercury managed? Who purchases this mercury? (2) How much mercury is released into the at mosphere from precious metals mines in
Nevada? Are reductions in emissions obser ved, due to the current voluntary mercury emissions reduction program?3 (3) What other sources of mercury from preci ous metals mining exist? What is the significance of those sources?

C. Mercury Background Mercury is a naturally occurring metal, and the only metallic element that is a liquid at ambient temperatures, having the appearance of a silver shiny metal. Mercury is 13.5 times heavier than water, although it is relatively volatile in the metallic state, with a vapor pressure
of 1.2 x 10 -3 torr at 20 o C (CRC, 1969). Mercury is geol ogically concentrated in regions associated with volcanic activity, high heat flow, and plate tectonic boundaries, and is commonly found associated with gold deposits although the ratio of mercury to gold in ore can vary widely. The mercury released to the living environment has increased since the industrial age, and the increased loading presumably has come from human activity (EPA, Mercury White Paper, 2003). The new non-an thropogenic mercury released into the living environment from natural sources (e.g. volca noes and geothermal sp rings) is generally assumed to be relatively constant over ge ologic time frames (Gustin, 2003). Mercury is known to cycle extensively in the atmosphere, and plant, soil and water systems involving complex processes that ar e not completely understood. Mercury undergoes extensive biological cycling in sediment s to toxic and biologic ally available forms
and back to stable and less av ailable sulfide complexes. Mercury can be photochemically released from soils as elemental mercury into the atmosphere, and, subsequently is transported in the atmosphere, where it is reoxidiz ed in the atmosphere to an ionic form and is deposited on soils, plants or water (Gustin, et al., 2004). Certain natura l sources of recycled mercury can be substantial (e.g. forest fires). Due to the difficulties in accurately measuring the loading of natural cyclical mercury, disagreement remains on the total mercury burden in
the environment. Various discussions on merc ury are available, and a recent extensive and widely considered overview is available from United Nations Environm ental Program website (UNEP, 2003) New anthropogenic mercury is that mercury th at is released into the living ecosystem from previously geologically isolated sources, and is most often derived from coal and metal mining activity, and, to a lesser extent from geot hermal heat recovery. Air emissions and land releases of new mercury from anthropogenic sour ces include electric ut ility facilities, lime4 kilns, chemical manufacturers, mining operations and other thermal pr ocesses that utilize fossil fuels. The U.S. EPA suggests that 1/3 of the total U.S. emissions of new mercury are deposited through wet and dry deposition in the continental 48 states. The remaining 2/3 is transported into the global rese rvoir outside the boarders of th e United States. One estimate has noted a total of 5,500 tons of atmospheric cyclical mercury is released into the global reservoir annually from natura l, oceanic, and newly produced anthropogenic emission sources (U.S. EPA, August 2003). Until 1998, the amount of mercury released into the atmosphere from gold mining activities had not been systematically measured, and reliable estimates from this sector were
not available. Since that time the amount of mercury released from mining to the atmosphere has been estimated, based on a series of emissi on measurements as a result of EPA’s Toxics Release Inventory (TRI) requirements. These estimates showed that a sizeable amount of mercury was being released from a small number of large mines, and subsequent efforts have
been made to reduce those emissions. Because gold mining is concentrated in Ne vada, and mercury releases from these mines is considered a significant environmen tal issue, we focused on Nevada gold mining operations. Some efforts were made to ex amine gold producing facilities out of state, although very little data is available. Governmental Regulations The U.S. EPA has developed an extensiv e array of regulatory requirements for atmospheric release of mercury. Summarized be low is a short list of dates for regulation of mercury in the U.S. Shortly after the passa ge of the 1970 Clean Air Act, as well as the increasing awareness of the toxicity of mercur y, domestic use began to decline, although a demand still exists and will likely continue.

Table C-1. Federal and State Regulations/Programs Affecting Mercury Year Federal Regulation Comments

1970 Clean Air Act Established EPA to set regulatory standards for hazardous air pollutants.

1971 In March of this year, mercury was designated a hazardous pollutant.5 1972 Federal Insecticide, Fungicide, and Rodentcide Act (FIFRA) Stopped the production of many pesticides which contained mercury.

1972 Federal Water Pollution Control Act Gave EPA authority to enforce and regulate the discharge of mercury into waterways.

1973 In September of this year, mercury was designated a toxic pollutant.

1973 In October of this year, the dumping of mercury or mercury compounds in the ocean became prohibited.

1974 Safe Drinking Water Act EPA was given the authority to establish and regulate safe standards for drinking
water.

1978 Resource Conservation and Recovery Act Regulations were established for the disposal of mercury-bearing waste.

1980 Comprehensive, Environmental Response, Compensation, and Liability Act Established a $1.6 billion fund for clean up of toxic waste sites.

1986 Emergency Planning and Community Right-to-Know Act
with Sec. 313 - TRI Required specific industries to report releases of over 650 chemical and chemical categories. Establishing Sec. 313 as the Toxic Release Inventory

1997 U.S. EPA changed TRI toxic release requirements and required the metal mining industry to report, beginning in
1998.

2001 Voluntary Mercury Reduction Program Four mining facilities in Nevada voluntarily agreed to VMRP goals on December 18 of this year.

2005 Clean Air Mercury Rule (Coal Fired Power Plants) New regulations designed to reduce mercury emissions from coal power plants.
* Jasinski, 1994 * State of Nevada, 2000 * U.S. EPA, 28 October 2003

The laws and regulations above were orig inally a response to excessive mercury releases from four specific emission industr ies, accounting for r oughly 83% of all 19956 anthropogenic emissions of mercury. These indu stries consist of medi cal waste incineration facilities (27% of total), munici pal waste combustion facilities ( 23% of total), utility boilers (21% of total) and commercial/industrial boilers (12% of total) (U.S. EPA, 1996). Mining
was not included in these totals. These valu es encompass both land release as well as atmospheric release, and the relative significance of these releases, as di scussed previously is related to the availability of me rcury in the receiving ecosystem.
Neither the U.S. EPA nor the Nevada Divi sion of Environmental Protection (NDEP) currently regulates mercury emissions from Ne vada mines, other than as water pollutants (Johnson, 2002). Except for primary mining of mercury, which no longer exists in the U.S., mercury emissions from mining operations are not regulated under th e National Ambient Air Quality Standards Act (NAAQS), the Nati onal Emission Standards for Hazardous Air Pollutants (NESHAP), or under Nevada’s Haza rdous Air Pollutants (NHAP) program. In spite of the fact that the larg er gold mines emit more mercury per facility than the average coal fired power plants, the imposition of regulati ons was seen as costly to both the regulating agency and to the mining industry (U.S. EPA, October 2003). One regulatory option
available to the EPA falls under the Clean Ai r Act allows the EPA to establish Maximum Achievable Control Technology (MACT) air em ission limits for the mining industry in a voluntary program. In late 2001 the EPA (R egion IX) and the NDEP, four gold mining companies in Nevada implemented a Voluntar y Mercury Reduction Program (VMRP) in their facilities. As part of this agreement, the four companies agreed to take proactive steps to reduce their mercury stack emissions by 50% in three years time. The Toxic Release Inventory for Nevada indicates that these four Nevada mining companies emit roughly 90% of all reported mercury from Ne vada. (U.S. EPA, October 2003). The participating Nevada facilities underwent investigations at each s ite to better understand mercury sources, to explore emission prevention so lutions, and then began implementation of these source reductions. Under this program atmospheric mercury emissions from Nevada gold mines have demonstrated decreases for atmospheric mercury release.

D. Mercury from precious metals mining Mercury is commonly observed in gold bear ing areas of Nevada, and a major mercury belt exists in western Nevada, although concentrations vary s ubstantially depending on each7 site. Reports of oncentrations of mercury in gold ore can range from undetectable to 0.01% by weight. (USGS, 2003; van Zyl and Eurick, 2001 ). Management of mercury generally falls in three categories; byproduct production capt ured for sale, atmospheric emissions, and wastes deposited on site, primarily as a minor co mponent of waste rock. (van Zyl and Eurick, 2001)

D. 1 By-Product Production Recoverable for Sale Extraction of gold from ore most commonly u tilizes basic solutions of cyanide as the lixiviant. Cyanide, in the presence of oxygen, converts elemen tal gold to a water soluble gold cyanide complex. These process fluids are then passed over activ ated charcoal, which captures the gold cyanide complex, and is thus removed from the aqueous solution. Mercury closely follows the chemistry and mechanism of ca pture of gold cyanide. In the presence of cyanide, mercury is converted to a highly water soluble di- or tetra-cy ano mercury complex.

Hg ++ + CN - Æ Hg(CN) 2 + Hg(CN) 4 2-

Mercury cyanide complexes are then captured with gold cyanide on activated charcoal and can ultimately be collected via retorts as liqui d metallic mercury (van Zyl and Eurick, 2001). This is the primary source of mercury recove red as a byproduct. Additional mercury can be collected from roasters or autoclaves using air pollution control pro cesses, although data on the amount of byproduct mercury collected from th ese processes is not generally available. Recovered byproduct mercury is placed in to either 76 pound or one-ton flasks and
stored on site until it can deliver ed to commercial facilities that are able to further refine the mercury for use in a variety of products. This report has examined only the Neva da byproduct mercury production. The byproduct production data were mostly obtained through voluntary reports from the various companies, because mercury by-product producti on is not reported in a publicly available
manner. We were unable to obtain informa tion on byproduct production in other states and also found that international by-product mercury production is not reported in a manner that is accessible. However, based on discussions with the recycling co mpanies that receive mercury from mines, byproduct mercury is pr oduced primarily from precious metals8 production, and these data will provide the majo rity of byproduct mercury production in the
U.S. Previous information on mercury by-produc t production was found to generally be
unreliable. There does not a ppear to be a systematic approach for recording mercury byproduct production in Nevada or the U.S., and wh en available, the data are incomplete. Because by-product mercury is not released into the atmosphere, land or water, it is not reported in the Toxic Release Inventory (TRI). Mercury production is, however, reported to the Nevada Tax Board on the annual reporting basi s in the Net Proceeds of Mineral reports. Due to the relatively diminutive totals, the Tax Board does not publish them in their annual bulletins (Ewell, 2003), and they are appare ntly not available to the public. The Nevada Division of Minerals has kept records of mercury production when the information was submitted. In Table 2-D, th e available Nevada data are provided. For example, in 1990, the total Nevada re ported mercury byproduct production was approximately 112 tons (plus 504 metric tons of primary mercury). For this same year, Sznopek and coworkers reported 114 metric tons for all of the U.S. mines. Nevada produced approximately 60% of the nation gold at that time (Nevada Bureau of Mines and Geology, 1993). This also did not include the Hycrof t/Crofoot/Lewis mine, wh ich produced about the same amount of gold in 1990 that it did in 1995 when it reported 24.5 metric tons of byproduct mercury. Sznopek and coworkers also reported 65 tons of U.S. byproduct mercury production in 1996 (Sznopek, et al, 199 9), a year when both Paradise Peak and Hycroft were still producing gold but did not report mercury produc tion, although Paradise Peak production had dropped substantially. In 1992, the EPA estimated that 70 tons of byproduct mercury was produced in the U.S. (EPA, July 2002), alt hough at that time both Paradise Peak and Hycroft mines were in full production, and while the mercury production at Paradise Peak was not reported, they produced 74 metric tons mercury in 1991, and up to 120 tons in previous years. Thus, the amount of mercury produced as byproduct mercury in the U.S. in previous years remains uncertain. At present, however, we are unaware of any remaining large producers of byproduct mercury in the precious metals mining industry. Both the Paradise Peak mine (now closed) a nd the Hycroft Mine (residual leaching) are no longer significant sources of mercury. Anothe r large producer of gold in California, the9 McLaughlin Mine, was historically a merc ury mine and produced byproduct mercury, although specific production data ar e not available (USGS, 1994). This mine is now closed.

Table D. 1. Reported mercury production from mine s in Nevada 1988-2000. All mines, except for the McDermitt Mine are gold mines. (from th e Nevada Division of Minerals files, 2003)
1988 1989 1990 1991 1992 1993 1994 1995 1996

- 1998 1999 2000

Hycroft 54,000 40,000 7,447 Paradise Peak 237,708 252,000 227,000 164,075

Alligator

Ridge 189

Newmont 5548 16,264 12,388 8,512 16,872 14,187 14,192
Alhambra 162
Borealis 1824 Hog Ranch 7,935 8,208
McDermitt (primary Hg mine) 846,488 1,008,216 0 0

Table D 2 is a breakdown in pounds of th e total amount of by-product elemental mercury recovered for sale for the four co mpanies. The by-product production totals, representing years 1999 – 2003 (partial) have be en provided directly from Barrick, Placer Dome , Queenstake (Jerritt Canyon mine, previ ously owned by Anglo Gold) and Newmont.

Table D. 2. Total Mercury By-Product Recovere d for Sale 1999-2003 (pounds and metric tons) ( data provided by each company, except where noted) 1999 2000 2001 2002 2003 Jerritt Canyon 4,041 4,313 3,709 5,045 Placer Dome 831 302 31,505 010 Barrick 13,629 22,850 55,457 49,208 Newmont (E. Operations) N/A 14,192 * 19,484 16,944 16,888 Newmont (W. Operations) N/A 7,986 8,367 11,891 Total pounds 41657 118,141 79564
Total Metric Tons 18.9 53.6 36.1
* From Nevada Division of Minerals data (total Newmont byproduct mercury)

As displayed in the Figure D-8, 53.6 t ons of by-product elemental mercury was recovered in 2001 by the four gold mining compan ies, and then subsequently sold into commerce. The spike of 2001 was largely due to the increase of mercur y recovered by Placer
Dome. The reduction in 2002 was due to the a ddition of a chemical agent, Cherokee UNR 811, during cyanidization at Placer Dome mines that kept the mercury bound to the rock. The data, as a whole show how different technologie s can affect mercury capture efficiency, as well as the differences in the mercury content in ore. Nevada precious metals mining companies generally store the by-product mercury for periodic sales to secondary production/recove ry companies who receive and, if necessary, further purify the mercury. These companie s include Bethlehem Apparatus Co. Inc., Hellertown, PA; D.F. Goldsmith Chemical and Metal Corp, Evanston, IL; and Mercury Waste Solutions, Inc., Mankato, MN (Reese, 2001). Th ese companies also remove mercury from a variety of products, including fluorescent lamps, dental amalgams, and a variety of control instruments. The received mercury is purified, by further retorting and washing, as necessary to meet the various product standards. Once th is process is complete, the recyclers will then sell the refined mercury to various industries that use it in commerc ial products such as lighting, dental amalgam, thermometers, etc. Barrick sells their by-product elemental me rcury recovered for sale to Bethlehem Apparatus in Bethlehem, PA. Cortez has sold its mercury to Mercury Waste Solutions in Union Grove, WI. and Newmont sells its mercury to the D.F. Goldsmith Chemical and Metal Corp. Phone discussions with representati ves of the three comp anies indicated that Bethlehem Apparatus and D.F. Goldsmith are th e largest recipients of by-product mercury. The D.F. Goldsmith representative reported appr oximately 20 tons of mercury received from the gold mining industry. During March of 2005, the price of a flask of mercury on web11 sources ranged to over $800/76 lb flask, and ha d risen from a price of approximately $200/76 lb flask the previous year. A representative of Bethlehem Apparatus indicated that they receive both metallic mercury, but also mercur ic chloride and mercur y-containing material from scrubbers and other mercury-trapping process material. Because the demand for mercury in the U.S. is larger than the current supply, mercury continues to be imported, and two of the three representati ves were interested in obtai ning information about mercury production from the mines, as well as contact info rmation. Each of the representatives, when asked if there were any problems in how merc ury was being transported to the secondary production facilities, reported that the procedures worked well and without notable problems.

Management Options: The U.S. still has a demand for mercury, 150-200 tons/year, although it has been substantially reduced ove r the past 30 years (S znopek and Goonan, 2000) due to increasingly strict regula tions on use of even small amount s of mercury in products. The mercury demand in 1996 was 372 tons, down fr om 720 tons in 1990. The current U.S. demand could be supplied by second ary recovery of stored mercur y or the strategic stockpile for several decades, currently re ported to be greater than 7000 tons from U.S. military and chlorine-caustic manufacturing facilities (B rooks, 2003). Because of the concerns about mercury toxicity, keeping mercury out of the environment continues to be a goal of both
national and international regulators and scientis ts, and suggestions have been advanced that mercury should be sequestered in repositories that prevent it from being added to the global burden of mercury (Bender, 2000). Such methods exist, and in clude conversion to mercuric sulfide and storage in permanen t repositories (UNEP, 2003). However, byproduct mercury, similar to recy cled mercury from a variety of products, is produced and needs to be managed in a safe and cost-effective manner. Byproduct mercury production is a minor component of the total mercury presently available, and the several 1-20 ton sources of bypr oduct mercury require management that is safe, reliable and, from an industry perspective, reduces liabilit y. Under the current le gal framework, liability for mercury is removed when the pr oduct is sold into commerce. Byproduct mercury production from gold mi ning is likely to increase, due to reductions in atmospheric emissions. While this in crease is likely to be relatively small, it is far more environmentally benign to produce byproduc t mercury for sale rather than release it12 into the air, or into waste f acilities. Since byproduct mercury will be produced, and, with the current demand (albeit decreasing), there appear s to be no compelling reason to establish a process for permanent sequestration of the byproduct mercury produced. Unless a mechanism and national (and international) policy and procedures exist for permanent retirement of mercury, retention of the pres ent market mechanism for management of the byproduct mercury from these several sources app ears prudent. Additionally, the significant price increase in mercury in th e recent past is ominous in th at primary mercury mines may again become economically feasible, and a ny mercury management of byproduct mercury that involves sequestration should co nsider the utility of this a pproach if the price structure encourages new mercury mine development, either in the U.S. or abroad. Management of metallic mercury is presently under extensive discussions in both the UNEP as well as the European Union, and byproduct mercury should be considered as a component (albeit relatively small) of the larger mercury management plans.

D. 2. Atmospheric Emissions of Mercury Because metallic mercury is a relativel y volatile liquid, it can escape to the atmosphere, particularly from thermal processe s. Several mercury sources from precious metals mining have been identified, and the amount released to the atmosphere can vary dramatically depending on the ore, the specific process and the effectiveness of the mercury
control measures. For those ores that are unoxidized, the singl e largest atmospheric source of mercury is
from sulfide or carbonaceous ore roasters, autoclaves or other thermal processes that convert reduced (sulfidic or carbonaceous) gold ore to a form that can be more efficiently extracted with cyanide. In these ores, mercury occurs primarily as mercury su lfide (HgS), which is also thermally oxidized and converted to either metallic (mostly) or divalent mercury. The metallic mercury is volatilized and released into the atmosphere, in the absence of any
controls.

HgS(s) + O 2 (g) + heat Æ Hg + SO 2 (g)13 A second major source of atmospheric release of mercury is from the processes that convert gold cyanide to dore bars. Because mercury follows gold through the processing circuit (discussed previously), and several of these processes utilize elevated temperatures, mercury (but not gold) is released into the atmosphere. These processes include electrowinning cells that convert gold to the elemental form and retorts specifically designed to remove and capture the mercury that is part of the metal sludge on the electrodes or a component of the gold that has been precipitated on zinc dust, sometimes in greater quantity than gold. In years past, an ecdotal accounts are common wher e no retort was utilized, and mercury condensed on the metal roofs of the proc essing facilities and formed visible droplets on the sides of the building. Finally, the charco al used to initially capture the gold cyanide and mercury cyanide complexes, is reused. However, it needs to be thermally treated for reactivation, and during this pr ocess residual mercury on the ca rbon can be volatilized. This
latter source can be a substantial fraction of the total amount of mercury released from a specific mine. For each of these sources of merc ury, control measures are available to capture a majority of the mercury, and are being utilized in mining. The efficiency of the capture of this form of mercury is variable, depe nding on the specific processes utilized. A third type of atmospheric release of vol atilized mercury from gold mining is from waste rock dumps, tailings facilities and extracted heap leach piles. This source of mercury is reported to be relatively minor, although methods for measurement of this volatilized mercury do not appear to be well-tested. Of the releases of mercury into the envir onment, the most problematic are those where exposure to living systems is most likely. While mercury release to land in a secure land fill may be of a much larger magnitude, this merc ury is most often unavailable and carries a relatively low risk. However, releases to surf ace water and to the atmosphere are much more biologically available and these releases, while much smaller, can present much greater environmental risks. Thus, atmospheric emi ssions are a particular concern for precious metals mining, since the quantities that have been released from several of the mines are large. Two sets of data have been used to estimate the recent and current amount of mercury released from precious metals mines in Nevada. The first is the TRI data and the second is the Voluntary Mercury Reduction program. Th ese data should be generally consistent, although some differences have been noted.14 D. 2. 1. TRI Reported Data The Toxic Release Inventory (TRI), was fo rmulated in 1986 within Section 13 of the Congressional Emergency Pla nning and Community Right-to-Know Act (EPCRA). This inventory requires specific industr ies to report releases of part icular chemical and chemical categories released to the air, land and wate r from industries rangi ng from energy production to metal mining. The “TRI is designed to pr ovide citizens with information about chemicals being used, processed, manufactured, or releas ed from facilities in their communities. The basic premise of TRI is that citizens have a ‘right to know’ about toxic chemicals that are handled or released in their community” (Sta te of Nevada, 2000). The EPA, in 1997, changed the TRI reporting requirements to include releases within the metal mining industry.
The section of TRI that is most relevant to this study is the Form-R. Form-R is broken into eight sections:
1. Reporting Year 2. Trade Secret Information 3. Certification

 This section states who is res ponsible for the fo rms authenticity. 4. Facility Identification 5. Parent Company Information and the Quantity of the Toxic Chemical Entering Each Environmenta l Medium On-Site

 This section encompasses all data fo r mercury released to land on-site. 6. Transfers of the Toxic Chemical in Wastes to Off-Site Locations

 This section gives the name of the off-site locatio n where mercury was sent for further refinement or disposal. 7. On-Site Waste Treatment Methods and Efficiency

 On-Site Energy Recovery Processes

 On-Site Recycling Processes 8. Source Reduction and Recycling Activities

 This section is an accumulative total of data from sections 5, 6 and 7.

 This section shows columnar references of data from the previous reporting year, the current reporting year, and exp ected reporting totals for two years in the future.

The data from Form-R is collected on pape r copies from the reporting facilities and sent to the appropriate regulat ory agency. Within a two year period, the forms are then finalized into electronic copy for public viewi ng over the web. In th is two year period, facilities can change a nd alter their respective Form-R if, for instance , it is found that there15 was an initial error in calculati ng release. It is the understand ing in this repor t that release documented in 2003 TRI paper copies are not fi nalized until the EPA finalization occurs in the summer of 2005. 2002 TRI reports were published on the web in the summer of 2005, and are therefore finalized. At the EPA’s TRI homepage ( www.epa.gov/tri/report/trime/ ), one can narrow down a search by chemical, f acility, or industry using the helpful TRI Explorer search engine application. Because the exact form of mercury is unknown (although assumed to be primarily metallic mercury, Hg o ) that is released into the atmosphe re, the total amount of mercury is expressed as “mercury” or “mercury compounds”. The atmospheric emissions are presented
below. Total Air Emission includes “Stack or Point Source Air Emissions” and “Fugitive or
Non-Point Air Emissions”. Stack or point source air emissions are from stacks, vents, pipes or ducts, while fugitive or non- point source air emissions is me rcury released from less well
defined sources. The EPA Report to Congress (1997) stated that in the US, the highe st concentration of anthropogenic emissions is east of the Rocky Mountains, and that the Great Basin region generally has the lowest emissions rates (ES- 10). Furthermore, th e Report suggests that combustion point sources, such as utility a nd industrial broilers make up for 86.9% of 1995 mercury emission in the United States (ES-6). On an indus try wide basis, Nevada gold mining is a relatively minor source of to tal natural and anthro pogenic emissions to atmosphere. However on an individual facility basis, gold mining emissi ons are significant. In 1998, four of the gold mines from Nevada reported individual facility mercury stack emissions totaling 13,560 pounds (U.S. EPA website, 2003). One facility alone, the Jerritt Canyon Mine, reported release of 9,400 pounds of the 13,560 pounds released by all of the reporting mines. In comp arison with the average coal-fir ed power plants in the East, emitting an average of 250-400 pounds per ye ar of mercury, Nevada gold mines are individually large sources of anth ropogenic emissions of mercury. Regulation of mercury releas es is complicated by the fact that mercury commonly occurs naturally in the earth and atmosphere . In the Report to Congress in 1997, the EPA estimated that 5,500 tons of new mercury was re leased world wide into the atmosphere in 1995 from all sources including natural emissions, oceanic emissions, and anthropogenic16 emissions. In the same year, it was reported that 159 tons (or 3% of total) were emitted into the atmosphere due to US human industrial sources, such as co al-burning utilities, municipal and hospital waste incinerators, industrial broilers, chlo r-alkali plants, and cement manufacturers (Report to Congre ss, 1997). The report did not include emissions originating from mining operations. In 1998, seven Neva da mines reported emission release of approximately 7 tons (or 4.3% of total US) of mercury emitted into the atmosphere (Johnson, 2000). In 2001, TRI data shows that four Ne vada mining companies released roughly 6 tons (or 8% of US total) of mercury and mercur y compounds as emissions. This amount dropped to 6.1% of the total U.S. emissions in 2002, and will likely be 3-4% in 2003, using the TRI
data.17 Table D 3. Mercury Air Emissions from Precious Metals Mining, 1998-2003. Toxics Release Inventory data, U.S. EPA, 2004)

Facility 1998 1999 2000 2001 2002 2003
Placer Bald Mountain 0 0 0 0 Barrick Goldstrike 1,500 1,400 1,467 1,243 1,253 1,122
Coeur Rochester 0 0 0 1 0 Cortez Joint Venture Pipeline 2200 1,500 1,351 1378 Echo Bay McCoy Cove (Newmont, 2003) 226 363 118 7

Florida Canyon Mine 2 1 1
Getchell 0 1 0 0
Glamis Dee 0

Glamis Marigold 4 0 1 Jerritt Canyon Joint Venture 9,400 9,400 6,700 7,990 4,740 793 Ken Snyder 11
Newmont Carlin North 3 3 2 24
Newmont Carlin South 53 71 80 490 513 565
Newmont Lone Tree 0 0 1 5 1 8
Newmont Rain 0 0 0
Newmont Twin Creeks 2200 1200 630 570 530 588 Ruby Hill 0 0 0 Smoky Valley Common 0 0 Total from Metal Mining (Point source- stack) 13,153 12,072 11,322 12,162 8,510 4488 (est.) Fugitive Nevada Total (from mining) 423 95 1,183 212 196

Nevada Total (all industries) 13,576 12,167 12,912 12,959 9,26618 Table D. 4. Ranking of states for atmospheric point source re lease of mercury and mercury compounds for 2001 and 2002 from all industries. Note that this list does not included the fugitive emissions, which are generally less than 10% of the point source (stack) emissions, except for West Virginia, Ohio and Alabama.

The TRI data show rather clearly that for the years 1998 to 2003, precious metals mining was the largest industrial so urce of atmospheric release of me rcury in Nevada. It also shows that Nevada, during 2001 had a #2 ranking for total mercury atmospheric discharge, and in 2002 was #4, and will probably decrease to #7 in 2003, based on preliminary data from Nevada mines and the expectation that approx imately 500 lbs would be emitted from the three coal fired power plants in Nevada. Based on discussions with staff at the Cortez Pipeline mine a mercury capture system on the carbon kiln is likely to result in a substantial reduction of mercury at that site. Thus, a decrease in total mercury release in 2005 to under 4000 lbs is anticipated. Further reductions in mercury are likely to be less drama tic than in previous

Rank (2002) State Pounds
released

(2001) Pounds
released

(2002) Pounds
released

(2003) 1 Texas 14,766 14,505 2 Ohio 11,405 9,625 3 Pennsylvania 9,089 9,177
4 Nevada 12,959 9,069 4500 (est) 5 Indiana 7,168 7,645 6 Illinois 5,963 5,610 7 Alabama 5,903 4,729 8 North Carolina 4164 4,507 9 California 5,668 4,173 10 West Virginia 6,282 4,051 11 Kentucky 5,256 3,67019 years, however and will depend on the type of ore being mined, as well as the improvements in mercury control technology that will be utilized.

D. 2. 2. Voluntary Mercury Air Emis sions Reduction Program (VMRP) data. As discussed previously, the four companies with the larg est emissions agreed in 2001 to participate in the Voluntar y Mercury Air Emissions Reduc tion Program. In lieu of a lengthy regulatory process, th e four companies, the Nevada Division of Environmental
Protection and the U.S. Environmental Prot ection Agency all agreed that a voluntary approach for reducing mercury emissions would be a much more rapid process for mercury reduction. Note that for the first 4 years of the TRI program for mining, only two of the
mines showed substantial reductions in mercur y emissions. With the voluntary program that was initiated in 2001, further reductions in emissi ons would be expected. The VMRP data are
much more extensive than found in the TRI reports, and the VM RP reports are available from
the Nevada Division of Envir onmental Protection (NDEP), but are summarized below. The actual reports provide additional detail a nd interested persons are referred to staff of the NDEP for a complete copy of the reports. Several issues should be noted regarding these data. First, the methods used dete rmine mercury are not generally provided, although individual reports discuss (e.g. Jerritt Canyon) issues of how me rcury is measured at various heights in the stacks, and how these affect estimates of atmospheric emissions. Second, the estimates of mercury release, are, in some cas es, based on actual source test measurements made two years earlier (e.g. Gold Quarry). While the data presented in the VMRP reports are the best available, imp roved methods for actually measuring mercury release are desirable, as would be incr eased testing frequency.20 Table D 5. VMRP data from Ba rrick Goldstrike (NDEP, 2004)

Source Emissions (2001, Baseline) Emissions (2002) Emissions (2003) Retorts 1,2,3 11 11 11 Mill furnace 1,402 161 161 Carbon column added.
March 2002 Electrowinning
cell 613 Included
above Included
above Emissions sent through
mill furnace carbon column
Carbon kiln 4380 4380 1927 Carbon filtration unit added in March, 2002
Autoclave
circuit 548 548 548 Controls installed prior to
2001 Roaster 814 814 166 Controls installed prior to baseline year
Total 7768 5920 281921 Table D 6. VMRP data from Cortez Joint Pi peline Project (Placer Dome) (NDEP, 2004)

Source Baseline
Emissions (1998) Emissions (2001) Emissions (2002) Emissions (2003)

Carbon in
leach 981.4 249.3 218.3 N/A

Carbon in
columns 14.7 41.2 67.4 Carbon column added

Area 28 heap leach pad
carbon
columns 134.8 234.7 293.9 Emissions sent through
mill furnace carbon
column

Refinery
furnaces 3174 160.2 473.3 Substantial reductions are
due to chemical treatment (see text)
Total 4305 685.4 105322 Table D 7. VMRP data from Jerri tt Canyon (Queenstake) (NDEP, 2004)

Source Emissions (2001) (Baseline) Emissions (2002) Emissions (2003)

Carbon regeneration
kilns 1543 294 0.28 Venturi mercury wet scrubbing/carbon polishing system installed in March Refinery 365 250 (included above) Emissions routed to carbon regeneration kiln control system in September
Roaster west 4667 2777 599 Sodium hypochlorite injection system installed in September,
2002 Roaster east 1405 1417 188 Sodium hypochlorite injection system installed in September,
2002
Total 7980 4738 78723 Table D 8. VMRP data from Twin Creeks Mine (Newmont) (NDEP, 2004)

Source Emissions (1999)
Baseline Emissions (2001) Emissions (2002) Emissions (2003) Comments

Autoclave phase
I 844 119 121 120 Venturi Scrubber

Autoclave phase
II 380 112 119 126 Venturi Scrubber

Retorts A,B,C,D 3 3 3 3 Carbon Columns Juniper kiln 252 253 268 125 Wet scrubber Electrowinning
cells 3 3 3 3

Pinion kiln 113 67 2 0 Wet scrubber
Induction
furnace 4 4 8 4

Total 1599 561 524 38124 Table D 9. VMRP data from Gold Quarry Mine (Newmont) (NDEP, 2004)

Source Emissions (2001)
Baseline Emissions (2002) Emissions
2003 Comments

Mercury Retorts 24.35 18.54 17.71 Mercury condenser and scrubber previously
installed Furnaces 15.19 15.72 11.43 Carbon adsorption unit previously installed Carbon kilns 31.23 30.74 55.40 Venturi scrubber; carbon adsorption unit previously installed
Prenant and
barren tanks 12.90 12.90 12.90 Carbon adsorption unit
and tank scrubber previously installed Ore Preheater 85.05 90.74 91.33 Baghouses and SO 2 scrubber previously
installed Ore Roaster 23.97 25.75 25.60 Wet scrubber, electrostatic precipitator,
SO 2 scrubber and
mercurous chloride scrubber previously
installed
Mill 6 drying/grinding
circuit 291 314 328 Baghouses for particulate

Total 484 508 54225 The differences between the TRI atmospheric emissions data and the VMRP data are, in some cases significant. For 2001, the Ba rrick Goldstrike mine reported 1324 pounds of atmospheric emissions, while for the VMRP data, Barrick reported 7768 pounds of atmospheric emissions. For the Cortez mine , 1503 pounds were reported for the TRI data in 2001 and for the VMRP data, 685 pounds were reported. The other differences for the 2001 data were relatively small: Jerritt Canyon (7,991 vs. 7980); Newmont Gold Quarry (South Operations Area) (603 vs. 508); Newmont Twin Creeks (501 vs. 561), respectively for TRI
vs. VMRP data. Differences in VMRP data a nd TRI data were also noted in subsequent years. As discussed previously, measuremen ts of mercury release are difficult, and the VMRP program appears to have increased th e focus on these measurements. As can be observed in the tables above, the amount of in formation from each source is substantially greater than presented in the TRI data. While data consis tency for mercury is warranted,
these somewhat inconsistent data show th e need for both agreement on the methods for
measurement and the number of actual measurem ent to ensure that the data provided is
consistent and accurate. Reliable methods th at will both reduce the co st of analysis and
allow much more convenient measurement of mercury in the various emission sources appears to be available. Frontier Geoscience s, a laboratory in Seat tle, Washington is now routinely measuring mercury at a cost of $100-$150 per sample (Bob Brunette, Frontier Geosciences, persona l communication, 2005). If the 2001 VMRP data are used, instead of the TRI data for atmospheric emissions, the total amount of mercury emitted to the atmosphere in Nevada in 2001 was 18,539 pounds, making it the state with the largest amount at mospheric emissions of mercury, with Texas now second at 14,766 pounds. However, the VMRP process is showing results. For 2002, the atmospheric emissions from these VMRP reporting mines had decreased, from 17,478 pounds in 2001 to 12,743 pounds in 2002, a 27% reducti on. Because several units of the control technology were implemente d in the last half of 2002, fu rther reductions for 2003 are noted, particularly the substa ntial reductions in mercury emissions from Jerritt Canyon.
One concern about the VMRP data that ex ists is the definiti on of the Maximum Achievable Control Technology (MACT) standards that have been applied to the gold mines. There does not appear to be a rigorous techni cal definition or comprehensive review of the26 definition of MACT, and this should be evaluate d as part of a larger discussion of mercury regulation in gold mines. For comparison purposes, the new Clean Air Mercury rule releas ed in March of 2005 (U.S. EPA, 2005) has provided limits for mercury emissions from coal fired power plants in each state. In 2002, TRI data showed that the three Nevada coal fired power plants released 524 lbs. of mercury to the atmosphere. The ne w mercury rule will requi re the total amount of mercury from these three plants and all new simi lar power plants to be no more than 570 lbs in 2010 and 224 lbs by 2018. This rule also requires extensive mon itoring of power plant
emissions to ensure that the re ported quantities are being measur ed on a routine basis. Thus, while gold mining emissions are not regulated u nder the new rule, the differences in mercury emissions between coal fired pow er plants in Nevada and gold mines are likely to be a topic
of discussion.

D. 3. Mercury released to surface impoundments or waste dumps: Because very large amounts of rock are excava ted in gold mines, particularly in open pit mines, the amount of waste rock containing merc ury is large and the total amount of mercury in these waste facilities is consequently very la rge, and constitutes the single largest release of mercury in the Toxics Release Inventory report s. For example, in 2002 the total amount of mercury released to surface impoundments or other land disposal was 4.68 million pounds. Similar amounts were reported in previous years. We have not included these data in this report, although they are available from the EPA Toxics Release Inventory web site.
While these releases are certain ly non-trivial, the large t onnages of mercury released do not provide a realistic sense of the relative risk of these sour ces of mercury. If the mercury
remains in the rock or other waste material a nd is appropriately contai ned in waste disposal units, it generally does not present an increase in environmental risk, compared to when that same mercury and rock were geologically isolated before the rock was br ought to the surface. Consequently these values, al though indeed very large, need to be considered with a perspective of risk. In certain circumstances, particularly in acidi c drainage, release of this mercury can be important in specific watersheds. Additio nally, a relatively unknow n component is the amount of mercury that is photoche mically released from this ro ck. Additional research is27 required to assess this source of atmospheric mercury, and whether it is a significant source, relative to other atmospheric releases. Undoubtedly, however, this risk will not be proportional to the large tonnage s reported in the TRI data.

D. 4. Company Profiles in the Volunt ary Mercury Reduction Program (VMRP) The companies represented in the VMRP in clude three of the largest gold mining companies in Nevada- Newmont, Barrick, and Placer Dome, and a mid-sized mining company, Queenstake. As shown in Table D-9, the gold production of these companies comprises about 80% of the total Nevada gol d production during these two years, and it has not appreciably changed since th at time. If Round Mountain Mine is included, jointly owned by Kinross and Barrick, the number increases to 87-89% of gold production in Nevada. The Round Mountain Mine has not reported signifi cant amounts of mercury released into the atmosphere from the TRI data, and apparently ha s a low mercury content in the ore. Also, based on TRI reports, >95% of the mercury rele ased to the atmosphere is reported by the VMRP companies. A short discussion of each mining company is presented below, to provide a background on the diversity of issues that exist with each mine and mercury. Substantial differences exist in ore type as we ll as approaches for control of mercury at each mine. Mercury emission controls are driv en by both the need to maintain worker environmental health and safety, as well as reduc tion in mercury released to the atmosphere.

Table D-9 Top 5 Gold Producing Mine Companies and Mines in 2000-2001 # Company Mine 2000 2001 1 Newmont Total 3,047,900 2,703,000 2 Barrick Betze-Post and Meikle 2,452,300 2,280,600 3 Placer Dome/Kennecott Cortez Joint Venture 1,009,000 1,188,100 4 Kinross/Barrick Round Mountain 640,100 747,000 5 Queenstake Jerritt Canyon Joint Venture 343,200 326,700
Total Nevada Gold
Production 8,585,000 8,125,00028 Jerritt Canyon Joint Venture Gold was discovered at Jerritt Canyon, 60 NE of Elko, NV, in 1973. Mining began in the summer of 1980 on approximately 125 squa re miles in the Independence Mountain Range. The first gold bar was produced on July 4, 1981. During that fi rst year, operation consisted of producing 23,000 oz of gold. T oday, Jerritt Canyon Joint Venture (JCJV) produces approximately 360,000 oz of gold annually. Until the mid-1990’s, JCJV conducted mostly surface mining. Surface mines were planned and permitted with the USFS and NDEP prio r to disturbance. Since then, JCJV has mined underground as they have identified ore bodies at increased depths. All underground mines are also planned and permitted with th e USFS and NDEP prior to disturbance. In conjunction with the Volunt ary Mercury Reduction Program, Jerritt Canyon has been upgrading their production pr ocesses with carbon filter syst ems. In 2001, JCJV spent $170,000 in carbon kiln upgrades for emission contro ls. In that same year, they spent $120,000 in a hypochlorite system for emission contro l in the roasters. Each year forward, JCJV will be spending roughly $60,000 per year in emission analysis of their facility. JCJV assumes there is approximately 1 milli on oz of gold remaining in reserves that will keep the facility operational for 3-4 more years. By adding up the total cost of control devices beginning in 2001 until the end of their anticipated reserves ( 2007), JCJV will have invested in the neighborhood of $1.25 million on environmental compliance upgrades. Average gold production of these dates is estimat ed at 300,000 per year. On average, control device spending at JCJV is r oughly $.60/oz of gold produced. The gaseous mercury emissions from Jerrit t Canyon’s two large roasters of mercury began to be treated with roas ter carbon scrubber systems in 2001. The fourth quarter of 2002 was when most of Jerritt Canyon’ s mercury controls were implemented for control processes. At the carbon regeneration k iln, Jerritt installed a ventur i mercury wet scrubbing/carbon polishing system that reduced emissions from a 2001 baseline by 81%. At their refinery, installation of ducting from the refinery to the carbon regeneration kiln system has reduced emissions from the 2001 baseline by 31.5%. Finally, Jerritt Canyon’s addition of a hypochlorite injection system in late 2002 produced the cumulative 90+% reduction in mercury emissions from the facility. The aggressi ve efforts at this mine have been primarily responsible for the substantial reductions in total mercury emitted by Nevada mines. This29 company mine went from being the single largest source of atmo spheric release of mercury in
the U.S. in 2001 to the lowest of the VMRP companies in 2003.

. Cortez Pipeline Joint Venture The Cortez Pipeline mine is located r oughly 90 miles South-West of Elko, NV, producing roughly 1 million oz of gold per year. Cortez has experienced elevated mercury in process fluids in the recent past. These c oncentrations equated to potential hazardous working conditions with potentially elevated e xposure levels of mercury to employees, and concerns about employee exposure were a prim ary driver for implem enting reductions in mercury in the process fluids. The majority of ore at this mine is oxide and does not require thermal treatment for precious metals recovery. In 1999 and in conjunction with the Vol untary Mercury Reduction Program, Cortez began initiating a chemical treatment using an organic dithiocarbamate mercury trapping agent from the Cherokee Chemical Co. called UNR-811. UNR-811 is added to process fluids. which then complexes aqueous mercury as a stab le organic sulfide precipitate (Upton, 2003). The complexed mercury is attached to either th e heap material, or is carried to the tailings impoundment as a complex aqueous slurry. Wh en trapped on heap material or rock, it does not appear to be remobilized, and represents a novel approach to management of mercury for reduction of exposure to workers as well as reduci ng mercury in the process fluids. In the past year, the efficiency of mercury capture on the solid material appears to have decreased somewhat and a significant increase of mercury release from the carbon kilns has been noted. In 2005 a mercury capture system will be added for capture of the mercury emissions from the carbon regeneration kilns and designed to su bstantially reduce the mercury release from this primary source.

Barrick Goldstrike Barrick Goldstrike, located roughly 60 miles North-West of Elko, NV, produces roughly 2 million oz of gold per year and is cu rrently the largest single gold mining complex in the United States. In 2001, Barrick complete d the development of a new roasting facility. This facility cost an estimate d $45 million (included in this pri ce is the cost of Research and Development). Barrick has estimated th at roughly 20 million oz of their estimated 3030 million oz of reserves will pass through the new facility for roasting; the remainder will be processed through their autoclave. Cost analysis would show that this ne w facility will cost Barrick roughly $2.25/oz of gold pr oduced, from its first ounce to it s final ounce in reserve. Barrick has two gaseous emission sources of mercury recovery (byproduct) within their facility. The first is at the roaster where mercury is recovered from the mercury scrubbing system. The second source of mercur y comes from the retort recovery process between the electro winning cells and the furn ace. All mercury collected on carbon scrubbers is roasted and the emissions are captured by the roaster mercury scrubber system.
Installations of wet venturi scr ubbers in the carbon kiln and auto clave circuit, carbon filters in the mill furnace, mercury condensers and carbon scrubbers in the retort units, and process controls in the roaster consisting of wet gas cond ensers a Hg absorption tower all contribute to the reduction in Barrick’s mercury emissions. This installation has a large and diverse array of mercury sources, as well as the dive rse array of mercury control methods.
All of the recoverable elemental mercur y by-product at Barri ck, recovered from oxidation at the roaster, is sold to Bethlehem Apparatus.

Newmont Gold Company Newmont has been actively mining a nd recovering gold in Northern Nevada since 1965. In Nevada, it currently mines from 14 open pits and 5 underground operations, and, combined with the international operations, is th e largest gold producer in the world. Unlike the other companies in the VMRP, Newmont has se veral sites in Nevada that potentially can produce mercury, although these ar e generally grouped into the we stern operations (primarily Twin Creeks) and the complex near Gold Qu arry in the Carlin Trend. At Newmont’s numerous operations in Nevada, two genera l technologies, wet sc rubbers and sulfurimpregnated carbon filters, are utilized for me rcury capture and management. Technologies utilized at Newmont have been in place for many years and many were in place prior to the requirement that mines report under the Toxic Release Inventory repor ting program and prior to the establishment of the Voluntary Mercury Re duction program. At one process area at the Twin Creeks mine, a new technology (to Ne wmont) uses of a wet scrubber with a hypochlorite solution, is being tested.31 Mercury recovered in the processes is ultimately captured in two refineries at Newmont’s operations in Nevada. Newmont’s byproduct mercury from Nevada is shipped to
DF Goldsmith.

E. Conclusions and Recommendations Nevada gold mines are a previously unr ecognized large source of atmospheric mercury releases, and constitute the largest sour ce of new byproduct mercury in the U.S. Data for estimating mercury released to the at mosphere has been avai lable only since the TRI reporting requirements were applied to mines in 1998 and only sporadica lly for the amount of byproduct mercury produced. Mercury conten t in ore is highly variable, and any
determination of releases of mercury to the air or bypr oduct production require direct
measurements at each mine. Future demand for commodity mercury in the U.S. is decreasing due to substitution of previous mercury-containing pr oducts. World demand is also decreasing, as manufacturing companies are turning away from its use in common household and industrial products. Ceramic composites are replacing dental amalgams, digitized instruments are replacing mercury thermometers, membrane cells are replac ing mercury cells in el ectrolytic production of chlorine and caustic soda, and indium co mpounds are being substituted for mercury in
alkaline batteries. Governme nts from many parts of the wo rld are regulating its use and manufactured applications, due to incr easing public concerns regarding mercury contamination and health warnings. However, mercury use remains in many products, and a
demand will continue to exist for the fore seeable future. Thus, byproduct mercury from precious metals mines is best managed via r ecycling facilities to meet that demand. A brief comment was made in the report co mparing mercury regulations in the coal fired power plants to mercury in gold mining an d while the mercury releases from gold mines are not included in the new mercury rule for pow er plants, it is useful to examine how these plants are meeting the new and stringent requirements. The analytical requirements for measurement of mercury in the power plants are potentially closely appl icable to gold mines as are the mercury cont rol technologies.

The following recommendations are ba sed on the findings of this study.32 1. The Voluntary Mercury Reduction Program, a cooperative effort of the four major producers of mercury has been successful fo r reduction of atmospheric mercury, based on TRI data. From a high of 13,576 lbs in 1998, th e release of atmospheric mercury has been reduced to 4488 lbs in 2003, and represents a 2/3 reduction, primarily from the Queenstake Jerritt Canyon Mine during this time period. Ap plication of a hypochlor ite technology at the Jerritt Canyon mine deserves special note, in th at it resulted in a >90% reduction in mercury released to the atmosphere from the roasters. 2. The data released to the Voluntary Mercury Reduction Program for atmospheric release are not completely consistent with the TRI data. While the inconsistencies are apparently based on different modeling efforts to predict total emissions, the data need to be
the best estimates and should be consistent in the various reports, or a clear explanation should be provided as a variance report. 3. Because of the complexity of the mercury emission sources, a systematic
evaluation of the methods used to determine mercury emissions rates and concentrations should be undertaken. EPA commonly has detailed protocols for measurement of contaminants in a variety of industries, a nd mercury release from mining is sufficiently different that a thorough study shoul d be made of how mercury release is measured at these sites, and development of common methods for use at these sites. As noted above, the methods used for measurement of mercury in th e coal power industry ar e probably applicable. 4. At present, it is very difficult to esti mate how much mercury is volatilizing from mine disturbed areas, particularly waste rock surfaces, compared to the naturally elevated background in Nevada. Furthe r study is required to determ ine if mercury emissions from these disturbed areas are significant relative to natural sources.
5. Each mine needs to establish a me rcury management program that includes a comprehensive mass balance understanding of the fa te of mercury that is removed from the original ore. This includes a determination of mercury in the various process fluids (before and after gold recovery), and in the ore that is subject to any heat treatment (before and after the treatment). This is in addition to the mercury emission monitoring, since the mass balance should be complete- any mercury that is not a ccounted perhaps should be considered released into the atmosphere. This mercury management program should be developed cooperatively33 with both the state and federal regulators and be required prior to a regulatory decision to open a mine. 6. Byproduct mercury production rates should be reported on a yearly basis to the Nevada Division of Minerals (or the USGS) and be made availabl e to the public. These data are important not only to Nevada , but on a national basis to have a better understanding of mercury pathways in commerce, and total me rcury accounting from the national inventory. 7. Byproduct mercury appears to be mana ged well by the participating members of the voluntary mercury reduction program. Sin ce a demand for mercury presently exists, and a good method for transfer of that mercury to merc ury recyclers exists, there is no present need to further regulate byproduc t mercury, other than a comprehensive mercury byproduct reporting requirement.
8. Either or both the U.S. EPA and the Ne vada should regulate mercury atmospheric emissions with the expectation that further atmo spheric release reductions can be realized. While the present VMRP has resulted in a s ubstantial reduction in mercury emissions, the lack of consistent reporting of mercury emissi ons, the lack of a required plan for mercury management at gold mines and the severe proble ms with mercury in biological systems all provide compelling reasons for the agencies to move forward in a cooperative manner to reduce mercury emissions from all present and future gold mines. Nevada apparently has the authority to independently regulate mercury emi ssions as a toxic chemi cal using its authority as designated state under the Clean Air Act. 9. A workshop on atmospheric emissions fr om gold mining should be held for the mining industry, involved analytic al laboratories, regul ators and other interested persons, to discuss methods for reduction of atmospheric mercury emissions and overall management of mercury in gold mines. These discussions s hould focus on mercury management at mines, analytical methods for measurement of mercury and development of procedures and protocols for reduction of mercury releases to the atmosphere.

Acknowledgements We wish to thank the U.S. EPA Region IX for support of this study, and representatives of the Stat e of Nevada NDEP (particularly Jolaine Johnson) and34 representatives of the VMRP companies for pr oviding valuable contri butions and comments on this report.35 F. References

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. Region 9: Cross-Program Activities . David Jones, Adam Browning. 28 Oct. 2003. ( http://www.epa.gov/region9/cro ss_pr/innovations/mining.html ) United States. Environmental Protection Ag ency, Office of Air Quality Planning and Standards, and Office of Research an d Development. Mercury Study Report to Congress. Volume I: Executive Summary. SAB Review Draft. June 1996. United States. Environmental Protection Agenc y. Office of Research and Development. “Assessing and Managing Mercury from Hist oric and Current Mining Activities.” Draft. 5 July 2002. United States. Environmental Protection Ag ency. Toxic Chemical Release Inventory Reporting Forms and Instructions . Revised 2002 Version.38 “Toxics Release Inventory (TRI) Program.” 18 March 2003. ( www.epa.gov/tri/report/trime ) United States. Environmental Protection Agenc y. March (2005) “Clean Air Mercury Rule: Basic Information: http://www.ep a.gov/air/mercuryrule/basic.htm Upton, Bill. Letter to the Nevada Divisi on of Environmental Protection. 16 Jan. 2003. van Zyl, D.J.A. and G. M. Eurick, “The Mana gement of Mercury in the Modern Gold Mining Industry” EPA Conference Proceedings on Mercury in the Environment, 2001.39 Appendix 1, Mercury Supply and Demand in the U.S

. Secondary Production/Recovery Chlor-Alkali plants are part of a growing source for secondary production/recovery of mercury for U.S. commercial products. In 2002, 15 of the 24 chlor-alkali plants in the U.S.
closed their doors. It was estimated in 1996 that an estimated 3,000 tons of recoverable mercury exist in all 24 U.S. sites (Sznopek, et all, 2000). The un-used mercury cells from these plant closures have re-entered the consum er market. Deep discoun ts are typically given for the sale of scrap mercury. Here again, as in the purchasing of by-product mercury from mining operations, refineries buy mercury cells used in the plants and retorts them to produce pure elemental mercury. The refinery then sells this mercury back to the market, creating a source of revenue for their company. The chlor-a lkali plants have then removed the liability of mercury, and in the process have gained a pe rcentage share of capital in return. Phase out periods for the remainder of the plants are e xpected to extend thir ty years (Sznopek and Goonan, 2000). Given this time frame and the estimated total of 3,000 tons recoverable, chlor-alkali plant are in a positi on of supplying the U.S. market with 100 tons of mercury per year for 30 years. United States Government Stockpile The U.S. Government stockpile is the final source for supply of mercury to the United States market. The US Department of Defense and the US Department of Energy owns, as of September 2002, a 4,435 ton stockpile of mercury (Brooks, 2003)This stockpile threatens the price of mercury, both in the US and abroad. If this stockpile is slated for release, then unit supply will magnify while the unit price will decrease. The government sold off quantities of the stockpile through 1994, however, due to envi ronmental concerns, sales has since been suspended (Brooks, 2002).

U.S. and World Sources of Elemental Mercury The EPA Report to Congress states that US mercury demand of manufacturers in a myriad of product applications can be attained from five main sources: (1) Primary production (2) By-product production recoverable for sale (3) Secondary production/recovery (4) Government stock40 (5) Imports Primary Production Primary production of mercury comes from mercury mines. The last primary mercury mine in the U.S. was the McDermitt mine in Northern Nevada. The mine shut down in 1990, after providing 448 metric tons of mercury in that y ear. U.S. primary mercury production peaked in the late 1970 ’s, producing 2,500 metric tons pe r year (Jasinski, 1994). Primary production mercury mines are still in operation in other countries, including Spain, China, Kyrgyzstan, Russia, Ukrane, Slovenia, and Algeria (Brooks, 2002). World production of primary mercury for 2002 was report ed to be 1,400 metric tons (Brooks, 2003). Between 1990 to 2000, the average world primar y production of mercury was 2,000 metric tons annually (Reese, 2001). World reserv es are reported to total roughly 600,000 metric tons, primarily located in Kyrgyzstan, Russia, Slovenia, Spain and the Ukraine (Brooks, 2003). Decreases in world demand for mercury, in la rge part due to environmental and health concerns, has been reflected in decreased pr oduction of primary mercury over the past two decades. Table A-1 are the production rates of the three largest producers of primary mercury by country, the world production yearly totals , and U.S. primary production totals pre 1991.

Table A-1 U.S. and World Primary Production (metric tons/year)
1979 1990 1998 1999 2000 2001 2002 Algeria 224 240 216 320 800 Kyrgyzstan 250 300 275 300 250 Spain 675 433 500 500 300
World Total 1,580 1,310 1,350 1,490 1,800
United States 2,500 448 N/A N/A N/A N/A N/A

* Source: Brooks, 2002

E. Supply and Demand Many legislative events have occurred over the years regarding publ ic health impacts of mercury, however, the single most significant event affecti ng mercury production and price41 has been the 1971 U.S. EPA declar ation that established mercury as a hazardous air pollutant. In recent years, Federal and State government s have implemented regulations that decrease the use of mercury in common household and co mmercial products. These efforts have been driven by the need to prevent mercury from entering our common waste streams. Several states have passed legislation which aim at the reduction of mercury in waste. Such legislation strives to ban the sa le of certain mercury-laden pr oducts and implement collection and recycling programs for these products. In addition to governmental regulations, a number of industry and non-governmental organizations have been maki ng impressive steps to reduce their use of mercury in the market products. According to Reese, the USGS reported the total 1998 U.S. demand for mercury was 200 tons. Consumption of mercury in 1990 was 720 tons. Consumption in 1980 was 2,042
tons. Market demand reveals a 90% reduction in mercury use in a twenty year period. 2001 demand totals for mercury are estimated at 200 tons, “estimated at 30% - 50% for chlorine manufacture, 30% - 50% for electronics, and th e balance for other uses such as dental applications, lamps, switches, and thermostat s” (Brooks, 2002). Historically, the highest domestic annual use of mercury has been in el ectrolytic production of chlorine and caustic soda, which has since dropped to second highest or 30% of domestic consumption (Reese, 2001). The highest use is reported to be in electrical consumption, 40% of domestic consumption for products such as oscillators, re lays, tilt-switches, batteries, and fluorescent lamps (Reese, 2001). The remainder of consump tion was used in various application products such as dental amalgams and control instru ments (Brooks, 2003). Mu ch progress has been made to reduce the use of mercury in comm on consumer products. Decrease in demand for mercury can be attributed to federal restrictions on additives in paint a nd pesticides, voluntary reductions in industries, state regulations on mercury in products, and recycling programs (EPA, Mercury White Paper). Alternative mate rials and recycling e fforts on manufacturer’s behalf have been the driving force behind the decrease in demand. Dome stic consumption of mercury will continue to decline as mercury is eliminated from products or as substitutes for mercury are made available. Major contributors to this effort have come from all types of ma nufacturing companies
and industries. In 2001 Ford announced that it had totally eliminated all mercury-containing
switches in their new vehicle lines. GM projects that by 200 4, all mercury lighting switches42 in their vehicles will be replaced with non-me rcury alternatives. The Mercury-Containing and Rechargeable Battery Management Act of 1996 se verely limited the sa le of most mercurycontaining batteries in the US. In anticipate d response, battery manuf acturers have reduced their use of mercury by over 98% since 1980. Batte ry manufacturers are tu rning to the use of nickel-cadmium, lithium, and zinc-air batterie s as a substitution (Brooks, 2003). Since 1985, mercury in a typical four-foot mercury lade n fluorescent bulb has been reduced by 75%. Health Care Without Harm, is currently in th e process of a campaign to end the sale of mercury thermometers at major pharmacy chains in the U.S. To date, several of the largest chains have already agreed to remove the produ ct from their stores, including Walgreen, WalMart, Rite-Aid and Albertson’s. Many industr ies are finding substi tutes for the use of mercury as well. For instance, chlorine and caustic soda electrolytic production is replacing mercury cells for diaphragm and membrane cells (Brooks, 2003). Dental amalgams are being replaced with ceramic composites and mercury thermometers are being substituted for digitized instruments (Brooks, 2003). Table A-2 shows the U.S. supply data from years 1993 – 2001. Annual supply totals is a combination of world imports for consum ption, industrial secondary recovery production, and up until 1994, shipments from the Nationa l Defense Stockpile (Reese, 1997). Brooks reports that on average, the U.S. was supplie d with 30% of its imports from the United Kingdom, 15% from Chile, 13% from Kazakhsta n, 13% from Germany, and the remaining
29% from other countries.
Table A-2 U.S. Mercury Supply (metric tons/year)

* Source: Reese, Mineral Commodity Summary, 1998 – 2001 * Source: Reese, Mineral Yearbook, 1997 – 2001 * Source: Brooks, 2002 * Source: Plachy, 1997 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 Imports for Consumption 40 129 377 345 164 128 62 103 100 209
Secondary Production:

Industrial Recovery 350 466 534 446 389 N/A N/A N/A N/A N/A

National Defense Stockpile 543 86 -- -- -- -- -- -- -- -- Mercury By-Product from Gold Mining N/A N/A N/A 65 N/A N/A 18.9 53.6 36.1 N/A
Total Supply 933 681 911 856 553 N/A N/A N/A N/A N/A Reported Demand 558 483 436 372 346 N/A N/A N/A N/A N/A43 * Source: Given by-product totals by Barrick, Cortez, Jerritt and Newmont Figure A-1 below graphically depicts th e decreasing U.S. supply and demand of mercury in the United States from 1965 – 2001. Total supply data from 1998 to present could not be found. Therefore, in the figure belo w, the graphical depiction stops in 1997. It is determined that the secondary supply produc tion from industrial reco very is a large enough number to warrant an incomplete total suppl y from years 1998 to present. Demand totals from 1998 were also difficult to determine, how ever it was noted that estimated demand for
2001 in the U.S. was 200 metr ic tons (Brooks, 2002).

Figure A-1

U.S. Mercury: Supply and Demand

0 500 1000 1500 2000 2500 3000

1965 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 2001Quantity (metric tons)

Demand Total US Supply

* Source: U.S. EPA 1997 Report to Congress * Source: Reese, 1997 – 2001 * Source: Brooks, 2002

The price of mercury has been very volatile during the 20 th century. There were significant price increases in the high demand periods of World Wars I and II, mostly for munitions production. The price peaked again in 1965, at $575 per flask, and has been in a steady decline since then. The 2002 price was $ 140 per flask (Brooks, 2003), and represents a 90% drop in price in 35 years, a lthough the price has clearly increased in the last two years. This continual decline in price is almost certainly associated with the health and environmental concerns surrounding mercury. Ongoing environmental concerns have resulted in numerous regulatory restrictions and/or elimination of mercury in various commodity applications altogether. Figure A-2 below, represents the typical supply chain where new elemental mercury will go in a product life cycle. Emissions and releases are not shown in the diagram,44 however, typical release and emission points o ccur throughout the supply chain functions.
Economic and environmental liabilities of me rcury are released from a company, once a transfer of ownership of mercury has occurred. This transfer might come in the form of the sale of the mercury or by giving it away to a cu stomer. It is unclear as to how many more years a mining company producing by-product mercury will be able to sell the metal and thereby release the liability. In time, conti nued mercury production will increase the potential liabilities for a mining company should demand fall.

Figure A-2 

### Mercury-laden Product Supply Chain

The concentration of mercury in ore varies substantially between ore bodies, and even within an ore body. Estimating of the concentrati on of mercury in ore and waste rock is based on rock sampling, and is generally highly variable . Concentrations of gold, as well as other elements contained within the ore and waste rock are determined on representative samples, and estimates provided for the TRI reports. By-Product Production

Secondary /Recovery Mercury Refinery Manufacturer

Consumer Primary Production, Imports and Government Stockpiles

Waste Dump Intermediary Recycling Efforts