US EPA Mining Review

7/31/2019 US EPA Mining Review

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Metal Mining Sector Notebook Project

SIC Code 10 September 1995

EPA/ 310-R-95-008

EPA Office of Compliance SectorNotebook Project

Profi le of the Metal Mining Industry

Sep tember 1995

Office of Comp lianceOffice of Enforcement an d Comp liance AssuranceU.S. Environm ental Protection Agency

401 M St., SW (MC 2221-A)Washington, DC 20460


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Sector Notebook Project Metal Mining

September 1995 iii SIC Code 10

Sector N otebo ok Contacts

The Sector N otebooks were d eveloped by the EPA s Office of Com pliance. Qu estions relatingto the Sector N otebook Project can be d irected to:

Seth H eminw ay, Coordinator , Sector Notebook ProjectUS EPA Office of Comp liance401 M St., SW (2223-A)Washington, DC 20460(202) 564-7017

Questions and comments regarding the individual documents can be directed to theap prop riate specialists listed below.

D ocument N umber Industry Contact Phone (202)EPA/ 310-R-95-001. Dry Cleaning Industry Joyce Chand ler 564-7073EPA/ 310-R-95-002. Electronics and Com puter Ind ustry* Steve H oover 564-7007

EPA/ 310-R-95-003. Wood Furniture and Fixtu res Ind ustry Bob Marshall 564-7021EPA/ 310-R-95-004. Inorganic Chem ical Ind ustry* Walter DeRieux 564-7067EPA/ 310-R-95-005. Iron and Steel Industry Maria Malave 564-7027EPA/ 310-R-95-006. Lum ber and Wood Prod ucts Ind ustry Seth Hem inw ay 564-7017EPA/ 310-R-95-007. Fabricated Metal Prod ucts Ind ustry* Scott Throw e 564-7013EPA/ 310-R-95-008. Metal Mining Industry Jane Engert 564-5021EPA/ 310-R-95-009. Motor Vehicle Assembly Industry Anthony Raia 564-6045EPA/ 310-R-95-010. Nonferrous Metals Industry Jane Engert 564-5021EPA/ 310-R-95-011. N on-Fu el, N on-Metal Min in g Ind ustr y Rob Lisch in sky 564-2628EPA/ 310-R-95-012. Organic Chemical Industry* Walter DeRieux 564-7067EPA/ 310-R-95-013. Petroleum Refining Industry Tom Ripp 564-7003EPA/ 310-R-95-014. Printing Industry Ginger Gotliffe 564-7072EPA/ 310-R-95-015. Pulp and Paper Industry Seth Heminway 564-7017EPA/ 310-R-95-016. Rubber and Plastic Industry Maria Malave 564-7027EPA/ 310-R-95-017. Stone, Clay, Glass, an d Con cr ete In du str y Scott Thr ow e 564-7013EPA/ 310-R-95-018. Tr an sp or ta tion Equ ip men t Clea nin g In d. Virgin ia Lath rop 564-7057EPA/ 310-R-97-001. Air Transportation Industry Virginia Lathrop 564-7057EPA/ 310-R-97-002. Ground Transportation Ind ustry Virginia Lathrop 564-7057EPA/ 310-R-97-003. Water Transportation Industry Virginia Lathrop 564-7057EPA/ 310-R-97-004. Metal Casting Industry Jane Engert 564-5021EPA/ 310-R-97-005. Pharmaceuticals Industry Emily Chow 564-7071EPA/ 310-R-97-006. Plastic Resin and Man-m ad e Fiber Ind . Sally Sasnett 564-7074EPA/ 310-R-97-007. Foss il Fuel Elect ric Power Generat ion Ind . Rafael Sanchez 564-7028EPA/ 310-R-97-008. Shipbuild ing and Repair Industry Anthony Raia 564-6045EPA/ 310-R-97-009. Textile Industry Belinda Breidenbach 564-7022

EPA/ 310-R-97-010. Sector Notebook Data Refresh-1997 Seth H em inw ay 564-7017EPA/ 310-R-98-001. Aerospace Industry Anthony Raia 564-6045EPA/ 310-R-98-002. Agricultural Chem ical, Pesticid e, and Amy Porter 564-4149

Fertilizer Indu stryEPA/ 310-R-98-003. Agricultura l Crop Product ion Industry Ginah Mortensen (913)551-7864EPA/ 310-R-98-004. Agricultura l Lives tock Product ion Ind. Ginah Mortensen (913)551-7864EPA/ 310-R-98-005. Oil and Gas Exp lor ation an d Pr od uction Dan Chad w ick 564-7054

IndustryEPA/ 310-R-98-008. Local Government Operations John Dombrowski 564-7036


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September 1995 v SIC Code 10

M ETAL M INING(SIC 10)

TABLE OF C ONTENTS

Page

LIST OF EXHIBITS ..........................................................................................................vi

LIST OF ACRONYMS ................................................................................................... viii

I. INTRODUCTION TO THE SECTOR N OTEBOOK PROJECT .................................... 1

I.A. Sum mary of the Sector Notebook Project ........................................1

I.B. Ad d itional Information ..................................................................... 2

II. INTRODUCTION TO THE METAL M INING INDUSTRY ....................................... 4

II.A. Introduction, Background, and Scope of the Notebook ................. 4

II.B. Characterization of the Metal Mining Ind ustry ..............................5

II.B.1. Indu stry Size and Distribution ........................................6

II.B.2. Econom ic Trend s............................................................. 10

III. INDUSTRIAL PROCESS DESCRIPTION ............................................................... 15

III.A. Indu strial Processes in the Metal Mining Ind ustry ....................... 15

III.B. Mining Process Pollution Outpu ts.................................................. 28

IV. W ASTE RELEASE PROFILE ............................................................................... 37

IV.A. Waste Release Data for the Metal Mining Ind ustry ...................... 37

IV.B Other Data Sources........................................................................... 46

V. P OLLUTION PREVENTION OPPORTUNITIES ................................................... 52

V.A. Controlling and Mitigating Mining Wastes................................... 54

V.B. Innovative Waste Management Practices ...................................... 58


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SIC Code 10 vi September 1995


TABLE OF C ONTENTS (C ON T 'D )

Page

VI. SUMMARY OF FEDERAL STATUTES AND REGULATIONS ............................... 69

VI.A. General Description of Major Statutes ........................................... 69

VI.B. Industry-Specific Requiremen ts...................................................... 80

VI.C. Pend ing and Proposed Regulatory Requirements ........................ 90

VII. C OMPLIANCE AND ENFORCEMENT PROFILE ................................................. 93

VII.A. Metal Mining Comp liance History ............................... 97

VII.B. Comparison of Enforcement Activity BetweenSelected Ind ustr ies .......................................................... 99

VII.C. Review of Major Legal Actions.................................... 104

VII.C.1. Sup plem ental Environm ental Projects........................ 104

VII.D. EPA H ard rock Mining Framew ork .............................................. 105

VIII. C OMPLIANCE ASSURANCE ACTIVITIES AND INITIATIVES ........................... 109

VIII.A. Sector-related Environm ental Program s and Activities ............. 109

VIII.B. EPA Voluntary Progr am s .............................................................. 114

VIII.C. Trade Association Activity ............................................................ 115

IX. C ONTACTS / A CKNOWLEDGMENTS / RESOURCE MATERIALS / BIBLIOGRAPHY ............................................................................................... 119


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September 1995 vii SIC Code 10


LIST OF EXHIBITS

Page

Exhibit 1 Total Mine Prod uction - USA, in Billions of Dollars ..................................6Exhibit 2 Geograp hic Distribution of Industry ............................................................7

Exhibit 3 Metal - Prod ucing Areas................................................................................8

Exhibit 4 Metal - Prod ucing Areas................................................................................8

Exhibit 5 Num ber of Facilities per State.......................................................................9

Exhibit 6 Major Uses for Selected Metal Minerals.......................................................9

Exhibit 7 Facility Size Distribu tion .............................................................................10

Exhibit 8 Metal Mine Produ ction - USA, in Billions of Dollars ...............................11

Exhibit 9 Sector-Specific Processes and Wastes/ Materials.......................................19Exhibit 10 Copp er Du mp Leach Op eration .................................................................22

Exhibit 11 Representative Hyd rometallurgical Recovery of Copper ........................23

Exhibit 12 Gold Heap Leaching Operation ..................................................................26

Exhibit 13 Chem icals Used in H igh Volume ......................................................... 27, 28

Exhibit 14 Volum e of Waste Generated for Selected Metals ......................................29

Exhibit 15 Steps in the Mining Process and Their Potential Environmental

Impacts .................................................................................................... 29, 30

Exhibit 16 Potential Mine Waste Mitigation Measu res......................................... 34, 35

Exhibit 17 Ecosystem Mitigation Measu res .................................................................36

Exhibit 18 Copper-Related Waste Releases..................................................................38

Exhibit 19 Lead and Zinc-Related Waste Releases......................................................39

Exhibit 20 Gold an d Silver-Related Waste Releases ......................40, 41, 42, 43, 44, 45

Exhibit 21 Pollutant Releases (Short Tons/ Year) ........................................................47

Exhibit 22 AIRS Releases ................................................................................... 48, 49, 50

Exhibit 23 Selected N PL Mining Sites ..........................................................................51

Exhibit 24 Waste Minimization an d Prevention Opp ortunities.................................59

Exhibit 25 Mine Water Managemen t Techn iques .......................................................66Exhibit 26 Mine Discharges Subject to Permitting .....................................................83

Exhibit 27 Mine Discharge Limitations ........................................................................84

Exhibit 28 Mill Discharge Limitations..........................................................................84

Exhibit 29 Five-Year Enforcement and Compliance Sum mary for the Metal MiningIndustry.........................................................................................................98


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SIC Code 10 viii September 1995


LIST O F EXHIBITS (C ON T 'D )

Page

Exhibit 30 Five-Year Enforcement and Compliance Sum mary for SelectedInd ustr ies ....................................................................................................100

Exhibit 31 One-Year Enforcement and Compliance Sum mary for Selected Ind ustries.....................................................................................................................101

Exhibit 32 Five-Year Enforcement and Comp liance Sum mary by Statute for SelectedInd ustr ies ....................................................................................................102

Exhibit 33 One-Year Inspection and Enforcement Summ ary forSelected Ind ustr ies .....................................................................................103

Exhibit 34 Sup plemental Environm ental Projects..................................................... 105


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SIC Code 10 x September 1995


LIST OF A CRONYMS (C ON T 'D )

N O X - Nitrogen Oxid e

N OV - Notice of ViolationN PDES - National Pollution Discharge Elimination System (CWA)N PL - National Priorities ListN RC - National Response CenterN SPS - N ew Source Performan ce Stand ard s (CAA)OAR - Office of Air and Rad iationOECA - Office of Enforcemen t and Comp liance AssuranceOPA - Oil Pollution ActOPPTS - Office of Prevention , Pesticides, and Toxic Substan cesOSHA - Occupational Sa fety and Hea lth Admin istr ation

OSW - Office of Solid WasteOSWER - Office of Solid Waste and Emergency ResponseOW - Office of WaterP2 - Pollution PreventionPCS - Permit Comp liance System (CWA Database)POTW - Pu blicly Ow ned Treatm en ts WorksRCRA - Resource Conservation and Recovery ActRCRIS - RCRA Information SystemSARA - Su p erfu nd A men d men ts an d Reau th orization ActSDWA - Safe Drin king Water ActSEPs - Su pp lem en tary En viron men tal ProjectsSERCs - Sta te Emergency Response CommissionsSIC - Stand ard Ind ustrial ClassificationSO2 - Sulfur Dioxid eSX/ EW - Solven t Extraction / ElectrowinningTRI - Toxic Release Inven toryTRIS - Toxic Release Inventory SystemTRIS - Toxic Chem ical Release Inven tory SystemTSCA - Toxic Substan ces Contr ol ActTSS - Total Suspend ed Solid sUIC - Und ergrou nd Injection Control (SDWA)

UST - Und ergrou nd Storage Tanks (RCRA)VOCs - Volatile Organic Comp ou nd s


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September 1995 1 SIC Code 10


I. I NTRODUCTION TO THE S ECTOR N OTEBOOK P ROJECT

I.A. Summary of the Sector Notebook Project

Environmental policies based upon comprehensive analysis of air, water,and land p ollution are an inevitable and logical supp lement to traditionalsingle-med ia app roaches to environmental protection. Environm entalregulatory agencies are beginning to embrace comprehensive, multi-statute solutions to facility permitting, enforcement and complianceassuran ce, edu cation/ outreach, research, and regulatory developmentissues. The central concepts driving the new p olicy direction are that

pollutant releases to each environmental medium (air, water, and land)affect each other, and that environmental strategies must actively identifyand ad d ress these inter-relationships by d esigning policies for the "whole"facility. One way to achieve a w hole facility focus is to designenvironmen tal policies for similar ind ustrial facilities. By doing so,environmental concerns that are comm on to the m anu facturing of similarprod ucts can be add ressed in a comp rehensive man ner. Recognition of the need to develop the industrial "sector-based approach within theEPA Office of Compliance led to the creation of this docum ent.

The Sector Notebook Project was initiated by the Office of Compliancewithin the Office of Enforcement and Compliance Assurance (OECA) toprovide its staff and managers with summary information for eighteenspecific ind ustrial sectors. As other EPA offices, States, the regu latedcommunity, environmental groups, and the public became interested inthis project, the scope of the original project w as expand ed . The ability tod esign comp rehensive, comm on sense environmental p rotection measuresfor specific industries is dependent on knowledge of several inter-relatedtopics. For the pu rposes of this project, the key elements chosen forinclusion are: genera l ind ustry informa tion (economic and geograph ic); adescription of industrial processes; pollution outputs; pollution

prevention opportunities; Federal statutory and regulatory framework;compliance history; and a description of partnerships that have beenformed between regulatory agencies, the regulated community, and thepublic.

For any given industry, each topic listed above could alone be the subjectof a lengthy volume. H owever, in ord er to prod uce a manageabledocument, this project focuses on providing summary information for


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SIC Code 10 2 September 1995

each topic. This format provides the read er with a synop sis of each issue,and r eferences w here more in-dep th information is available. Text withineach profile was researched from a variety of sources, and was usuallycondensed from more detailed sources per taining to specific topics. Thisapproach allows for a wide coverage of activities that can be further

explored based u pon the citations and references listed at the end of thisprofile. As a check on the information includ ed , each notebook wentthrou gh an external review process. The Office of Comp lianceappreciates the efforts of all those that participated in this process andenabled us to develop more complete, accurate, and up-to-datesumm aries. Many of those wh o reviewed th is notebook are listed ascontacts in Section IX and may be sources of ad d itional information. Theindividuals and groups on this list do not necessarily concur with allstatements within this notebook.

I.B. Additional Information

Providing Comments

OECA's Office of Compliance plans to periodically review and update thenotebooks and will make these updates available both in hard copy andelectronically. If you have any comm ents on the existing notebook, or if you would like to provide additional information, please send a hardcopy and computer disk to the EPA Office of Compliance, SectorNotebook Project, 401 M St., SW (2223-A), Washington, DC 20460.

Comments can also be uploaded to the Enviro$en$e Bulletin Board or theEnviro$en$e World Wide Web for general access to all users of thesystem. Follow instructions in App end ix A for accessing these d atasystems. Once you have logged in, procedu res for up loading text areavailable from the on-line Enviro$en$e Help System.

Ad apting N otebooks to Particular N eeds

The scope of the existing notebooks reflect an approximation of therelative national occurrence of facility typ es that occur w ithin each sector.

In many instances, industries within specific geographic regions or Statesmay have unique characteristics that are not fully captured in theseprofiles. For this reason, the Office of Comp liance encourages State andlocal environmental agencies and other groups to supplement or re-package the information included in this notebook to include morespecific industrial and regulatory information that may be available.Ad ditionally, interested States may w ant to sup plement the "Sum mary of Applicable Federal Statutes and Regulations" section with State and local


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requ irements. Comp liance or technical assistance providers may alsowant to d evelop the "Pollution Prevention" section in more detail. Pleasecontact the appropriate specialist listed on the opening page of thisnotebook if your office is interested in assisting us in the furtherd evelopm ent of the information or policies add ressed w ithin this volum e.

If you are interested in assisting in the development of new notebooks forsectors not covered in the original eighteen, please contact the Office of Compliance at 202-564-2395.

Because this profile was not intended to be a stand-alone documentconcerning the metal mining industry, appended is a full reference of additional EPA documents and reports on this subject, as listed in theMarch ed ition of the Fed eral Register.


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II. I NTRODUCTION TO THE M ETAL M INING INDUSTRY

This section provides background information on the size, geographicdistribution, employment, production, sales, and economic condition of the metal mining ind ustry . The type of facilities described w ithin the

document are also described in terms of their Standard IndustrialClassification (SIC) codes.

II.A. Introduction, Background, and Scope of the Notebook

The metal mining industry includes facilities engaged primarily inexploring for metallic minerals, developing mines, and ore mining . Theseores are valued chiefly for the metals they contain, which are recoveredfor use as constituents of alloys, chemicals, pigments, or other products.The industry sector also includes ore dressing and beneficiatingoperations. The categorization correspond s to the Stand ard Ind ustrialClassification (SIC) code 10, pub lished by th e Departm ent of Commerce totrack the flow of goods and services within the economy.

The SIC 10 group consists of the following three-digit breakout of industries:

SIC 101 - Iron OresSIC 102 - Copper OresSIC 103 - Lead and Zinc Ores

SIC 104 - Gold an d Silver OresSIC 106 - Ferroalloy Ores, Except VanadiumSIC 108 - Metal Min in g Serv icesSIC 109 - Miscellaneous Meta l Ores.

Although the group includes all metal ore mining, the scope of miningindustries with a significant domestic presence is concentrated in iron,copper, lead, zinc, gold, and silver. These represent the most commonhardrock minerals mined domestically, and comprise an essential sectorof the nation's economy by providing basic raw materials for major

sectors of the U.S. econom y. In ad d ition, the extraction an d beneficiationof these minerals generate large amoun ts of wastes. For these reasons,this profile's focus is limited to the above-stated sectors of the SIC 10metal mining ind ustry.

While such metals as molybdenum, platinum, and uranium are alsoincluded in SIC code 10, mining for these metals does not constitute asignificant portion of the overall metal mining industry, nor of the waste


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generation in mining processes; these metals are therefore excluded fromthis p rofile.

In the global market, the U.S. is a major producer of iron, copper, lead,zinc, gold, and silver. In 1993, d omestic mines were respon sible for six

percent of iron ore production, 13 percent of copper ore production, 13percent of lead production, eight percent of zinc production, 14 percent of gold prod uction, and 11 percent of silver prod uction. Despite anextraordinary wealth of domestic metal sources, with the exception of gold , the U.S. is a net imp orter of all the above-mentioned metals.

Regulations pertaining to the industry are numerous, but an emphasis isplaced on p oint source discharges to wa ters, regulated by the Clean WaterAct. These ind ustries also face existing and futu re regulation un der theClean Water Act, Comprehensive Environmental Response,Comp ensation and Liability Act, and the Clean Air Act. Unlikemanufacturing facilities, facilities involved in mining metals are notcurrently required to report chemical releases and transfers to the ToxicRelease Inventory (TRI) Public Release Database under the EmergencyPlanning and Comm un ity Right-To-Know Act of 1986. As a result, TRId ata is not available as a source of information on chemical releases in th emetal mining industry; alternative sources of data have been identifiedfor pu rposes of this profile.

II.B. Characterization of the Metal Mining Industry

The metal mining industry is predominantly located in the WesternStates, wh ere most copper, silver, and gold min ing occurs. Iron oreproduction is centered in the Great Lakes region, while zinc miningoccur s in Tennessee and lead min ing in Missour i. Large comp anies tendto dom inate mining of such m etals as copp er, silver, and gold, w hile morediverse mine operators may be involved in mining lead, zinc, and ironmetals. Metals genera ted from U.S. min ing opera tions are useddomestically in a wide range of products, including automobiles,electrical and indu strial equipm ent, jewelry, and ph otographic materials.

Metal mine production has remained somewhat stagnant over recentyears, and metals exploration has d eclined , althoug h future prod uction isexpected to climb as a result of continued indu strial manu facturing an d agrowing economy.

The following exhibit depicts the proportion of metal mining productionwithin the entire mining ind ustry.


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Exhibi t 1Total Mine Production - USA, in Billions o f D ollars

IndustrialMinerals &Aggregates

Coal

Metals$20

$21.60

$10.40

Source: Randol Minin g Directory 1994/95.

II.B.1. Industry Size and D istribution

Variation in facility counts occur across data sou rces du e to many factors,includ ing reporting and d efinition differences. This d ocum ent does notattempt to reconcile these differences, but rather reports the data as theyare maintained by each source.

Geographic Dist ribution

Though mining operations are performed throughout the U.S., theconcentration of metal mining is located in the Western region of thecoun try. Copper, gold, and silver dep osits are primarily foun d in Utah,

Montana, Nevad a, California, and Arizona. Zinc is mined primar ily inAlaska, Missour i, N ew York, and Tennessee. Lead d eposits are minedprimarily in Missouri, Alaska, Colorado, Idaho, and Montana, whileMinnesota and Michigan are the primary sources of domestic iron oreprod uction. The U.S. Bureau of Mines lists 482 active mines in its 1994Mineral Commodity Summ aries. (See Exhibits 2, 3, and 4). Exhibit 5


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Exhib its 3 & 4Metal-Produ cing Areas


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Exhibi t 5N umber of Facili ties per State

Type of Facility/ Total Number

States and N umber of Mines

Iron Ore (22) MI-2; MN-7; MT-1; SD-1; TX -2; UT-2

Sil ver (150) AK-15; AZ-15; CA-14; CO-4; ID-12; MI-1; MT-9; NV-1; NY-1; OR-1;SC-3; SD-4; UT-4; WA-4Gold (212) AK-13; AZ-14; CA-19; CO-7; ID-11; MT-9; NM-5; NV-61; OR-2; SC-4;

SD-5; WA-4; UT-2Lead (23) AK-2; AZ-1; CO-2; ID-1; IL-1; MO-7; MT-2; NM-2; NY-2; TN-2;

WA-1Zinc (25) AK-3; CO-1; ID-2; MO-4; MT-1; NY-2; TN-10; WA-1Copper (50) AZ-16; CO-2; ID-3; MI-3; MO-2; MT-3; NM-9; NV-1; OR-1; UT-1

Source: U.S . Bureau of Mines 1992 and 1994 Data.

Metals mined under SIC 10 are used for a wide variety of products, andare the primary raw m aterials used in many ind ustrial app lications. Asnoted in a series of Technical Resource Documents prepared by EPA'sOffice of Solid Waste, copper is essential to the electronics andconstruction industry; iron ore provides the base material for the steel,automotive, and transportation industries; gold is used primarily in

jewelr y an d the d ecora tive a rts, but is a lso used in the electron ics industryand in dentistry. Gold also serves as an important investment vehicle andreserve asset. All of these metals are essential to the opera tion of amod ern economy. Exhibit 6 provides a more d etailed list of the uses forthese metals.

Exhibi t 6Major Uses for Selected Metal Min erals

Commodity Numberof Mines Major Uses

Total U.S.Production

(metric tons )Copper 50 Build ing construct ion, elect r ica l and elect ronic products,

industrial machinery and equipment, transportationequipment, and consumer and general produ cts

1,765,000

Gold 212+ Jewelry and arts, industrial (mainly electronic), dental 329Iron Ore 22 Steel 55,593,000Lead 23 Transportat ion (bat teries, fue l tanks , solder, sea ls , and

bearings); electrical, electronic, and communicationsuses

398,000

Silver 150 Photographic products, e lect r ica l and elect ronic,electroplated ware, sterling ware, and jewelry

1,800

Zinc 25 Galvanizing, d iecast alloys, brass, and bronze 524,000Source: U.S. Bureau of Mines, Mineral Commodity Summaries 1994, and Minerals Yearbook, Volume I: Metals and

Minerals, 1992.


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The number of companies that have shifted portions of their explorationbu dgets to Latin Am erica is grow ing. More than 250 companies, abou t 10percent of the North American mining exploration industry, are nowactive in Latin Amer ica, especially Mexico and Chile. Among the forces

driving U.S. companies abroad is the recent privatization of world-classmineral deposits, the presence of rich overseas ore deposits, depletion of prime domestic ore sources, labor costs, and the lack of significantregulatory pressure in the developing world .

The U.S. econom y's slow bu t steady grow th rate of the last several years isexpected to spur demand in major domestic materials-consumingindu stries, such as the auto ind ustry. In add ition, d eveloping economiesin South America and Asia have had higher consumption of mineralmaterials as political regimes have liberalized their economies to meetd emand s for higher standard s of living.

The following exhibit illustrates production values in 1993 for variousmetal mining indu stry sectors.


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Exhibi t 8Metal Mine Production - USA , in Billions of D ollars

Copper

Gold

Iron Ore

Zinc

Magnesium

Lead

Molybedenum

0.00 1.00 2.00 3.00 4.00 5.00

1993

1992

$4.18

$3.65

$1.73

$0.67

$0.36

$0.31

$0.19

$3.60

$3.79

$1.70

$0.51

$0.41

$0.27

$0.16

1993 Tota l Value (e stima ted )$10.439 b illion

Source: Randol Minin g Directory 1994/95.

Following is a brief summary of current trends in domestic miningindu stries. Much of the information presented is based on a reportprepared by EPA's Office of Research and Developm ent.

Iron

In 1993, domestic production of iron ore remained at approximately thesame level as that of 1992. The value of usable ore shipp ed from mines inMinnesota, Michigan, and six other States in 1993 was estimated at $1.7billion. Iron ore was pr oduced d omestically by 16 companies operating22 mines, 16 concentration plants, and 10 pelletizing plants. The mines

includ ed 19 open pits and one und ergroun d operation. Nine of thesemines, operated by six companies, accounted for the vast majority of theoutput.

The U.S. steel industry was the primary consumer of iron ore, accountingfor 98 percent of d omestic iron ore consu mp tion in 1992. Domesticdemand for iron ore has fallen behind that for iron and steel due tochanges in industrial processes, including the increased use of scrap


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(especially by mini-mills) and the use of imported semi-finished steel.Twelve percent of domestic iron consumption in 1993 was imported.While world consumption of iron ore increased slightly, prices declinedfor the third consecutive year.

Copper

World copper production remained at approximately the same level in1993 as in 1992, while world consumption of refined copper declined.However, refined copper demand in the U.S. and Canada ran counter tothe world trend . Domestic dem and for copp er rose by app roximatelyeight percent in 1993; the U.S. impor ted six percent of its copp er needs in1993. Consum ption w as expected to increase in 1994 to more than 2.4million tons, up from th e previou s year's 2.3 million tons. Domestic brassmills (a mixture of copp er and zinc) ran at capacity.

Copper was recovered at 50 mines in 1993, and the top 15 minesaccounted for more than 95 percent of prod uction. The primary end usesfor copp er are bu ilding constru ction (42 percent), electrical and electronicproducts (24 percent), industrial machinery and equipment (13 percent),transportation equipment (11 percent), and consumer and generalprod ucts (10 percent).

According to Stand ard & Poor's, the copp er m ining indu stry is dominatedby three producers (ASARCO Incorporated, Cyprus Amax MiningCompany, and Phelps Dodge), which are financially viable operations.

However, not all copper mining firms are as healthy financially. From1989 to 1992, the industry was characterized by decreasing operatingrevenues and net income, while short and long-term liabilities increasedfor some comp anies. With the recent economic recovery, how ever, theoverall outlook for the copp er ind ustry is finan cially secure.

Lead

The U.S. imp orted 15 percent of its lead need s in 1993. Transp ortation isthe major end use for lead, with approximately 83 percent being used to

prod uce batteries, fuel tanks, solder, seals, and b earings. Electrical,electronic, and commun ications uses, amm un ition, TV glass, constru ction,and protective coatings accounted for more than nine percent of leadconsumption.

According to the U.S. Bureau of Mines, U.S. lead production hasremained relatively constant through 1994, while prices for leadcontinued an u pw ard trend that began in 1993. Consump tion of lead in


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pr ice of silver. As a result, U.S. mine p rod uction of silver declined for thefourth consecutive year, and three major silver producers had negativenet income. Silver pr ices have recently begun to rise, how ever; w ith theprospect of continued higher prices, some companies are consideringresuming operations at currently inactive mines.

The U.S. is a net imp orter of silver. One hu nd red a nd fifty mines in 14States mined silver in 1993. However, Nevad a, Idah o, Arizona, andMontan a accounted for 74 percent of all d omestic prod uction. Estimatedend -uses for 1993 were as follows: ph otograp hic prod ucts (50 percent);and electrical and electronic prod ucts (20 percent).


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III. Industrial Process Description

This section describes the major industrial processes within the metalmining industry, including the materials and equipment used, and theprocesses emp loyed . The section is d esigned for those interested in

gaining a general un derstand ing of the ind ustry, and for those interestedin the inter-relationship between the industrial process and the topicsdescribed in subsequent sections of this profile -- pollutant outputs,pollution preven tion opp ortunities, and Fed eral regu lations. This sectiondoes not attempt to replicate published engineering information that isava ilable for this ind ustry. Refer to Section IX for a list of ava ilablereference documents.

This section describes commonly used production processes, associatedraw materials, the byproducts produced or released, and the materialseither recycled or transferred off-site. This d iscussion, coup led w ithschematic drawings of the identified processes, provide a concised escription of w here wastes may be prod uced in the process. This sectionalso describes the potential fate (air, water, land ) of these wa ste prod ucts.

III.A. Industrial Processes in the Metal Mining Industry

Much of the following information has been presented previously inreports and issue papers drafted in support of various EPA offices,includ ing th e Office of Solid Waste, the Office of Pollution Prevention and

Toxics, and the Office of Enforcemen t and Comp liance Assurance. For acomplete listing of reference documents, please see Section IX.

Metals are mined from two types of d eposits. The first, lode d eposits, areconcentrated dep osits that are fairly w ell-defined from surrou nd ing rock.Iron, copper, lead, gold, silver, and zinc are mined mainly from loded eposits. The second type of d eposits, placer deposits, occur w ith sand ,gravel, and rock; they are u sually d eposited by flowing wa ter or ice, andcontain metals that were once part of a lod e deposit. Only a smallpercentage of domestic gold an d silver is derived from p lacer d eposits.

There are three general app roaches to m ining metals:

Surface or open-pit mining requires extensive blasting, as well as rock,soil, and vegetation removal, to reach lode d eposits. Benches are cut intothe walls of the mine to provid e access to progressively deeper ore, asup per-level ore is dep leted. Ore is removed from the mine andtransported to milling and beneficiating plants for concentrating the ore,


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and smelting, and / or refining. Open pit mining is the primary dom esticsource of iron, copp er, gold, and silver.

Underground mining entails sinking a shaft to reach the main body of ore. "Drifts," or passages, are then cut from the shaft at variou s dep ths to

access the ore, which is removed to the surface, crushed, concentrated,and refined . While un dergr ound mines d o not create the volume of overburd en w aste associated w ith surface mining, some w aste rock m uststill be brought to the surface for disposal. Waste rock may either beretur ned to the mine as fill or pu t in a d isposal area. In the U.S., onlylead, antimony, and zinc are solely und erground operations.

Solution or fluid mining entails drilling into intact rock and usingchemical solutions to dissolve lode dep osits. Du ring solution mining, theleaching solution (usually a dilute acid) penetrates the ore, dissolvingsoluble metals. This pregnant leach solution is then r etrieved for recoveryat a solvent extraction and electrow inning (SX/ EW) plan t. This meth odof mining is used in some parts of Arizona, Nevad a, and New Mexico torecover copper.

Historically, the primary mining method has been underground mining.However, with the advent in recent decades of large earth movingequipment, less expensive energy sources, and improved extraction andbeneficiation technologies, surface mining now prevails in most industrysectors. Open-pit min ing is generally more economical and safer thanunderground mining, especially when the ore body is large and theoverbu rd en (surface vegetation, soil, and rock) relatively shallow . In fact,the lower cost of surface mining has allowed mu ch lower-grade ores to beexploited economically in some ind ustry sectors.

Metal mining processes include extraction and beneficiation steps duringprod uction. Extraction removes the ore from the groun d , wh ilebeneficiation concentrates the valuable metal in the ore by removingun wa nted constituents. Often, more than one metal is targeted inbeneficiation processes. For examp le, silver is often beneficiated an drecovered with copp er. The beneficiation meth od selected varies w ith

mining operations and depends on ore characteristics and economicconsiderations.

The following sections provide more detail on extraction methods andbeneficiation processes, as they r elate to the mining of each metal.


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Ext raction Processes

As described in a report drafted for EPA's Office of Pollution Preventionand Toxics, extraction involves removing any overburden, then drilling,blasting, and m ucking the broken ore and waste rock.

Mobile rigs drill holes in rock, which can then be filled with explosivesfor blasting waste rock and ore. Potential pollutants involved in this stepin the mining process include the fuel, lubricants, and hydraulic oilsconsum ed b y the rigs; fuels and oils typ ically contain su ch constituen ts asbenzene, ethylbenzene, and toluen e.

Explosives (usually a mixture of ammonium nitrate and fuel oil) are usedto break up the rock. Other explosives, includ ing trinitrotoluen e (TNT)and nitroglycerine, may also be used.

Mucking is the process of removing broken ore from the mine, using avariety of loading and hauling equipment to transport ore to a mill forbeneficiation. Depend ing on ore volume, trucks, rail cars, conveyers, andelevators may all be required to hau l ore. Equipment involved in thisstep of the mining process uses hydraulic fluid (containing glycol ethers);batteries (containing sulfuric acid, lead, antimony, and arsenic); andlubricants and fuel (containing p etroleum hyd rocarbons).

Beneficiation M ethods

Ore beneficiation is the processing of ores to regulate the size of theproduct, to remove unwanted constituents, or to improve the quality,pu rity, or grad e of a d esired prod uct. Und er regulations d raftedpu rsuant to the Resource Conserva tion an d Recovery Act (40 CFR 261.4),beneficiation is restricted to the following activities: crushing; grinding;washing; dissolution; crystallization; filtration; sorting; sizing; drying;sintering; pelletizing, briqu etting; calcining to remove wa ter and / orcarbon dioxid e; roasting, autoclaving, and / or chlorination in p reparationfor leaching; gravity concentration; magnetic separation; electrostaticseparation; flotation; ion exchange; solvent extraction; electrowinning;

precipitation; amalgamation; and heap, dump, vat, tank, and in situleaching.

The most common beneficiation processes include gravity concentration(used only with placer gold deposits); milling and floating (used for basemetal ores); leaching (used for tank and heap leaching); dump leaching(used for low-grad e copper ); and magn etic separa tion. Typicalbeneficiation steps include one or more of the following: milling;


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washing; filtration; sorting; sizing; magnetic separation; pressureoxidation; flotation; leaching; gravity concentration; and agglomeration(pelletizing, sintering , briquetting, or nod ulizing).

Milling extracted ore produces uniform-sized particles, using crushing

and grind ing processes. As man y as three crushing steps may berequ ired to red uce the ore to the desired p article size. Milled ore in theform of a slurry is then pu mp ed to the next beneficiation stage.

Magnetic separation is used to separate iron ores from less magneticmaterial, and can be classified as either high- or low-intensity (requiringas little as 1,000 gau ss or as much as 20,000). Par ticle size and the solidscontent of the ore slurry determine which type of magnetic separatorsystem is used .

Flotation uses a chemical reagent to make one or a group of mineralsad here to air bubb les for collection. Chemical reagents includ e collectors,frothers, antifoams, activators, and depressants; the type of reagent usedd epen ds on the characteristics of a given ore. These flotation agents maycontain sulfur dioxide, sulfuric acid, cyanide compounds, cresols,petroleum hydrocarbons, hydrochloric acids, copper compounds, andzinc fume or d ust.

Gravity concentration separates minerals based on differences in theirgrav ity. The size of the par ticles being separa ted is imp ortan t, thu s sizesare kep t un iform with classifiers (such as screens and hyd rocyclones).

Thickening/filtering removes most of the liquid from both slurriedconcentrates and mill tailings. Thickened tailings are d ischarg ed to atailings impoundment; the liquid is usually recycled to a holding pondfor reuse at the mill. Chemical flocculants, such as alum inum sulfate,lime, iron, calcium salts, and starches, may be added to increase theefficiency of the thickening process.

Leaching is the process of extracting a soluble metallic compound froman ore by selectively dissolving it in a solvent such as water, sulfuric or

hyd rochloric acid , or cyanide solution. The d esired metal is thenremoved from the "pregnant" leach solution by chemical precipitation oranoth er chem ical or electrochem ical process. Leaching method s includ e"du mp ," heap," and "tank" operations. Heap leaching is widely used inthe gold ind ustry, and d um p leaching in the copp er ind ustry.

The following exhibit summ arizes the various pr ocesses used w ithin eachmining sector, and the p rimary wa stes associated with those processes.


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Exhibi t 9Sector-Specifi c Processes and Wastes/Materials

Sector Mining Type Beneficiation/Processing Primary Wastes/Materials

Gold-Silver Surface Underground In Situ(experimental)

Cyanidation Elution Electrowinning/ zinc precipitation Milling Base metal flotation Smelting Amalgamation (historic)

Mine water * Overburden/ waste rock Spent pr ocess solutions Tailings Spent Ore

Gold Placer Surface Gravity separation Roughing, cleaning, fine separ ation Some magnetic separation

Mine water* Overburden/ waste rock Tailings

Lead-Zinc Underground(exclusively)

Milling Flotation Sintering Smelting

Mine water* Overburden/ waste rock Tailings Slag

Copper Surface Underground In Situ

Milling Flotation Smelting Acid leaching SX/ EW recovery Iron precipitation/ smelting

Mine water* Overburden/ waste rock Tailings Slag Spent ore Spent leach solutions

Iron Surface (almostexclusively) Underground

Milling Magnetic separation Gravity separation Flotation

Agglomeration Blast furnace

Mine water* Overburden/ waste rock Tailings Slag

* N ote: M ine water is a waste if it is discharged to the env ironment via a point sourceSource: U.S . EPA, Office of Solid Waste, Technical Document , Background for

N EPA Reviewers: Non-Coal M inin g Operations.

Below is a more detailed discussion of the various beneficiation methodsand processes used for each of the sectors presented in the table above.

Iron O re

Typical beneficiation steps applied to iron ore include: milling, washing,sorting, sizing, magnetic separation, flotation, and agglomeration.Milling followed by magnetic separation is the most commonbeneficiation sequence used, according to the American Iron OreAssociation. Flotation is pr imarily used to up grad e the concentratesgenerated from magnetic separation, using frothers, collectors, andantifoams.


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Steel mills generally agglomerate or pelletize the iron ore concentrates toimp rove blast furnace opera tions that utilize iron ore. Pelletizingoperations produce a moist pellet (often using clay as a binder), which isthen hard ened through heat treatment. Agglomeration generates by-

prod ucts in the form of particulates and gases, includ ing compou nd s suchas carbon d ioxid e, sulfur compoun d s, chlorides, and fluorid es. Theseemissions are usually treated using cyclones, electrostatic precipitators,and scrubb ing equip ment. These treatment technologies generate iron-containing effluent, which is recycled into the operation. Agglomerationprod uces large volumes of sulfur d ioxide and nitrogen dioxide.

Copper

Copper is commonly extracted from surface, underground, and,increasingly, from in situ opera tions. Accord ing to the U.S. Bureau of Mines, surface mining accounted for 83 percent of copper production in1992, with underground mining accounting for the remainder. In situmining is the practice of percolating dilute sulfuric acid through ore toextract copper, by pumping copper-laden acid solutions to the surface forsolvent extraction/ electrow inning (SX/ EW). This leaching opera tion usesboth amm onium n itrate and sulfuric acid.

Beneficiation of copper consists of crushing and grinding; washing;filtration; sorting and sizing; gravity concentration; flotation; roasting;autoclaving; chlorination; dump and in situ leaching; ion exchange;

solvent extraction; electrow inning ; and precipitation. The method sselected vary according to ore characteristics and economic factors;approximately half of copper beneficiation occurs through dumpleaching, wh ile a combination of solvent extraction/ frothflotation/ electrowinning is generally used for the other half. Often, morethan one m etal is the target of beneficiation activities (silver, for examp le,is often recovered w ith copp er).

According to EPA's Office of Solid Waste Technical Resource Document ,copper is increasingly recovered by solution methods, including dump

an d in situ leaching . Because most copp er ores are insolub le in water,chemical reactions are required to convert copper into a water-solubleform; copper is recovered from a leaching solution through precipitationor by SX/ EW. Solution beneficiation method s accoun t for app roximately30 percent of domestic copper production; two-thirds of all domesticcopper mines use some form of solution operations. Typical leachingagents used in solution beneficiation are hydrochloric and sulfuric acids.Microbial (or bacterial) leaching is used for low-grade sulfide ores,


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Exhibit 10Coppe r D ump Leach Operation

CopperRecovery

Plant

PregnantLeachate

Oxygen Depleted Air

Impermeable Lineror Bedrock

Temp. InactiveArea

Leach SolutionPercolatingDownward

Collection Pondand Dam

Fresh Air

Dump

Fresh AirLeachSolution


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Lead and zinc mineral concentrates that will be smelted an d refined mayrequ ire sintering, typ ically per formed at the smelter site. Sinteringpartially fuses the ore concentrates into an agglomerated material forprocessing, and involves several steps. First, ore concentrates are blend ed

with moisture and then fired (sintered) and cooled. During cooling, thesinter is crushed, grad ed, and further crushed to prod uce a smaller sinterprod uct. By-prod ucts of the roasting and sintering processes includ esulfur dioxide, nitrogen d ioxide, and carbon monoxid e. Residu esgenerated also includ e du st and primar y lead p rocess wa ter.

Gold and Silver

Three principal techniques are used to process gold and silver ore:cyanide leaching, flotation of base metal ores followed by smelting, andgrav ity concentration. Accord ing to the U.S. Bureau of Mines, cyanideleaching generated 88 percent of all domestic lode gold in 1991, and 38percent of silver. Processing of base metal ores prod uced 11 percent of the gold; over half of the silver produced in 1991 was from smeltingconcentrates prod uced by flotation of silver and b ase metal ores. Gravityconcentration is used primar ily by gold an d silver placer op erations.

Cyanide leaching is a relatively inexpensive method of treating gold oresand is the chief method in use. In this techniqu e, sodium or potassiumcyanide solution is either applied directly to ore on open heaps or ismixed with a fine ore slurry in tanks; heap leaching is generally used to

recover gold from low-grade ore, while tank leaching is used for highergrad e ore.

Compared to tank leaching, heap leaching has several advantages,including simplicity of design, lower capital and operating costs, andshorter start-up times. Depend ing on the local topograp hy, a heap or avalley fill meth od is typically emp loyed. The size of heap s and valley fillscan range from a few acres to several hu nd red. Heap leaching mayinvolve any or all of the following steps:

Preparation of a pad with an impervious liner. Some liners maysimply be comp acted soils and clays, while others may be of moresoph isticated design, incorpor ating clay liners, french d rains, andmu ltiple synth etic liners.

Placement of historic tailings, crushed ore, or other relativelyun iform an d pervious material on the up perm ost liner to protect itfrom dam age by heavy equ ipment or other circum stances.


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Cru sh in g an d/ or agglom eratin g th e ore.

Placing the ore on the p ad (s).

Applying cyanide solu tion using drip , spray, or pond i rr igat ionsystems, with ap plication rates generally betw een 0.5 and 1.0pou nd s of sodium cyanid e per ton of solution. This is known asthe bar ren solution b ecause it contains little or no gold.

Collecting the solution via piping laid on the liner, ditches on theperimeter of the heap, or pipes/ wells laid th rough the heap intosum ps at the liner surface. The recovered p regnant solution, nowladen w ith gold (and silver), may b e stored in p ond s or routedd irectly to tanks for gold r ecovery, or it may be reapp lied to theheap for ad d itional leaching.

Recover ing the gold from the pregnant so lu t ion (typicallycontaining between 1 and 3 ppm of gold).

The leaching cycle can r ange from w eeks to several months, d epend ing onpermeability, size of the pile, and ore characteristics. The average leachcycle is app roximately three mon ths.

Recovery of gold from the pregnant solution is accomplished usingcarbon adsorption or, less commonly, by direct precipitation with zincd ust. These techniqu es may be used separately or in a series with carbonad sorption followed by zinc precipitation. Both methods separate thegold-cyanid e comp lex from other remaining w astes. Carbon ad sorptioninvolves pu mp ing the p regnant solution into a series of activated carboncolum ns, which collect gold from the cyanid e leachate. The preciousmetals are then stripped from the carbon by elution with the use of aboiling caustic cyanide stripp ing solution, or similar solution. Gold in thepregnan t eluate solution m ay be electrowon or zinc precipitated.

Although carbon adsorption/ electrowinning is the most comm on methodof gold recovery domestically, zinc precipitation is the most widely usedmeth od for gold ore containing large amoun ts of silver. In zincprecipitation, pregnant solution (or the pregnant eluate stripped fromcarbon) is filtered and combined with metallic zinc dust resulting in achemical reaction which generates a gold p recipitate. The solu tion is thenforced through a filter that removes the gold.


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The following exhibit illustrates a typical gold heap leach op eration u singzinc precipitation; variations exist in exact processes and methods used ateach operation.

Exhibit 12Gold Heap Leaching Operation

VacuumTower

Clarifier

ZincFeeder

SodiumCyanide Lime

ZincFilterPress

Pregnant PondOre

Heap

Leaching Pad

Barren Pond

Refinery

Solution Sprinklers

Source: U.S . EPA, O ffice of Enforcement and Compliance Assurance.

To prepare for tank leaching , ore is ground to expose the m etal values tothe cyanide. Finely ground ore is slurried w ith the leaching solution intanks. The resulting gold-cyanide complex is then ad sorbed on activatedcarbon. The pregnant carbon then un d ergoes elution, followed either byelectrow inning or zinc pr ecipitation, as d escribed previou sly. Therecovery efficiencies attained by tank leaching are significantly higher


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than for heap leaching. The tank leaching process may occur over a seriesof days, rather than the w eeks or months required in h eap leaching.

After heap leaching and rinsing, the spent ore becomes waste and is leftas is or is deposited in d isposal areas similar to those used for w aste rock.

Spent ore may contain w astewater from rinsing the ore, residu al cyanide,metal-cyan ide comp lexes, and sm all quantities of heavy m etals. Tailingsproduced from tank leaching may contain arsenic, barium, chloride,nitrate, sodium , and su lfate. Cyanide resid ues may requ ire d estructionusing alkaline chlorination, ozone, or hyd rogen p eroxid e ad d ition.

Gravity concentration , a beneficiation method used mostly in placermines, involves passing a slur ry of ore and water over a series of riffles tocatch heavier gold par ticles. Amalgamation, or wetting metallic goldwith m ercury to form an amalgam , is another recovery technique used inplacer operation s. Its high cost, inefficiency for large-scale miningoperations, and environmental and safety considerations have greatlyrestricted am algamation's previous w idespread use.

Chemical Usage

The following exhibit lists the chem icals used in greatest volum e in themetal mining processes for several of the main comm odities. Whilevolum e does not necessarily correlate with p otency, this data ind icateswhich chemicals are present in greatest quan tity, and to wh ich chemicalsmine w orkers may be m ost frequently exposed. Although it does not

app ear in the chart below, cyanide is also consum ed in m assive qu antitiesby the gold ind ustry. In 1990 alone, Dow Chemical supp lied over 160million poun ds of reagent-grad e cyanide for use in gold m ining,accord ing to the Chicago Tribune (Febru ary 2, 1992, p.27).

Exhibit 13Chemicals Used in Hig h Volume

Type of Mine Chemical Name Volume/Mass at Mine SiteIron Ore Acetylene 5,577,726 gallons

Argon 15,892,577 gallons

Diesel Fuel 3,417,487 gallonsNitrogen 9,398,026 gallons

Lead/Zinc Acetylene 1,021,795 gallonsCalcium Oxide 932,129 lbs.Diesel Fuel No. 2 1,640,271 gallonsPropane 171,733 lbs.; 1,015,962 gallonsSulfur Dioxide* 1,843,080 lbs.


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Exhib it 13 (cont'd)Chemicals Used in Hig h Volume

Type of Mine Chemical Name Volume/Mass at Mine SiteCopper Acetylene 10,909,868 gallons

Calcium Oxide 512,620,243 lbs.

Chlorine** 17,242,059 lbs.; 138,015 gallonsCoal 2,375,684,593 lbs.Copper oreconcentrate**

24,000,000 lbs.

Copper Slag 10,833,500 lbs.Diesel Fuel No. 2 47,301,433 gallonsLimestone 154,280,000 lbs.Natural Gas 8.6 x 10^12 gallonsNitrogen 189,315,331 gallonsPyrites 38,400,000 lbs.Su lfu ric Acid ** 82,907,916 lbs.; 5,772 gallons

Gold Acetylene 829,460 lbs.; 2,033,041 gallons

Calcium Oxide 58,394,968 lbs.Chlorine** 66,090,022 lbs.; 165 gallonsDiesel Fuel No. 2 13,425,408 gallonsPropane 1,218 lbs.; 2,743,927 gallonsSulfuric Acid** 1,800,501 lbs.

Source: NIOSH 1990/91* Prop osed TRI chemical** Current TRI chemical

III.B. Mining Process Pollution Outputs

The extraction and beneficiation of metals produce significant amounts of waste and byp rodu cts. Total waste produ ced can range from 10 percentof the total material mined to w ell over 99.99 percent. The volum e of totalwaste can be enormous: in 1992, gold mining alone produced over 540million metric tons of waste. The following exhibit pr ovides fur therd etail on the volume of produ ct and waste material generated from m etalmineral mining.


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Exhibit 14Volume of Waste Generated for Selected Metals

Commodity N umberof Mines

Total CommodityProduced(1,000 mt)

TailingsGenerated(1,000 mt)

Other WasteHandled(1,000 mt)

Copper 50 1,765 337,733 393,332Gold +212 0.329 247,533 293,128Iron Ore 22 55,593 80,204 106,233Lead 23 398 6,361 --Silver 150 1.8 2,822 --Zinc 25 524 4,227 --

Source: U.S. Bureau of Mines, Mineral Commodity Summaries 1994 and Minerals Yearbook, Volume I: Metals and Minerals, 1992.

The industry (including non-metallic minerals) is estimated to havegenerated 50 billion metric tons of waste through 1985, and currently

genera tes appr oximately one billion metric tons annu ally. It is imp ortantto note, how ever, that virtually none of this annu al prod uction related toextraction and beneficiation is classified as RCRA hazardous waste.Exhibit 15 summarizes some of the potential effects of industrial miningon the environment.

Exhibit 15Steps i n the Minin g Process and The ir Potential Envi ronmental Impacts

MiningProcess

ProcessWastes

Air Emissions Other Waste Land, Habitat, Wildlife

SitePreparation

Erosion d ue toremoval of vegetation

Exhaust fromconstructionvehicles;fugitive dust

Run-off sediment

Deforestation and habitatloss from road and siteconstruction

Blasting/ Excavation

Acid Rock Drainage(ARD); erosionof sediments;petroleumwastes fromtrucks

Dust blown tosurroundingarea; exhaustfrom heavymachinery

Non-reusedoverburden;waste rock

Loss of habitat; increase inerosion; loss of plantpopulation from d ust andwater pollution; reductionin localized ground waterrecharge resu lting fromincreased r unoff; loss of fish pop ulation from water

pollution; nearby structuraldam ages from vibrationand settling; competitionfor land u se

Crushing/ Concentration

Acid Rock Drainage(ARD) fromtailings

Dust createdduringtransportation

Additionalwaste r ock;tailings


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Exhib it 15(cont'd)Steps i n the Minin g Process and The ir Potential Envi ronmental Impacts

MiningProcess

ProcessWastes

Air Emissions Other Waste Land, Habitat, Wildlife

Leaching ARD; wa ter

pollution fromruptures inpipes or pond sholding leachsolution

Sludges from

neutralization of contaminatedwater

Loss of plant, fish, and

water fowl p opulationfrom w ater pollution

Source: M inin g Support Package,. Draft, U.S. EPA, April 1994.

Wastes

Several wastes are created when metal ores are extracted from the earth.The first is overburd en an d waste rock, which is soil and rock rem oved inorder to access an ore or mineral body . Overburd en typically includ essurface soils and vegetation, wh ile waste rock also includ es rock removedwhile sinking shafts, accessing or exploiting the ore body, and rock embedd ed w ithin the ore or mineral body.

Most overburden and waste rock are disposed of in piles near the minesite, although approximately nine percent is backfilled in previouslyexcavated areas, and nearly four percent is used off-site for construction.Waste rock dumps are generally constructed on unlined terrain, withunderlying soils stripped, graded, or compacted depending onengineering consid erations. Drainage systems may be incorporated into

dump foundations to prevent instability due to foundation failures fromgroun d w ater saturation, and may be constructed of gravel-filled trenchesor gravel blankets.

Tailings are a second type of common mining w aste. Most beneficiationprocesses generate tailings, which contain a mixture of impurities, tracemetals, and residue of chemicals used in the beneficiation process.Tailings usually leave the mill as a slurry consisting of 40 to 70 percentliquid mill effluent and 30 to 60 percent solids; liquids are commonly re-used in milling processes. Most mine tailings are disposed in on-siteimpound ments. Design of the impound ment depend s on naturaltopography, site conditions, and economic factors; generally it iseconomically advantageous to use natural depressions to contain tailings.Impoundments are designed to control the movement of fluids bothvertically and horizontally.

In some cases, tailings are d ewatered or d ried and d isposed in p iles; thisminimizes seepage volumes and the amount of land required for an


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impou nd ment. How ever, d ry disposal method s can be prohibitivelyexpensive du e to add itional equipm ent and energy costs.

Slurried tailings are sometimes disposed of in underground mines asbackfill to provide groun d or w all supp ort. This d ecreases the above-

ground surface disturbance and can stabilize mined-out areas.Subaqueous tailings disposal, practiced primarily in Canada, is theplacement of tailings below a p erman ent w ater surface such as a lake orocean; it is used primarily to minimize the acid-generating potential of tailings by preventing sulfide ore from oxid izing. This d isposal meth od isnot curren tly practiced comm ercially in the United Stated .

Water Water removed from a mine to gain or facilitate access to an ore body isknow n as mine wa ter. Mine water can originate from precipitation, fromflows into pits or und erground workings, and/ or from ground wateraqu ifers that are intercepted by the mine. Mine water is only a waste if itis d ischarged to the environment via a point source. Mine water can be asignificant problem at m any m ines, and enormou s quan tities may have tobe pu mp ed continuou sly d uring operations. When a mine closes,removal of mine water generally ends. How ever, un dergr ound mines canthen fill and mine water may be released through adits or fractures thatreach the surface. Sur face mines that extend below the w ater table fill tothat level when pumping ceases, either forming a lake in the pit orinund ating and saturating fill material. Pum ped mine wa ter is typicallyman aged in on-site impou nd ments. Collected water may be allowed to

infiltrate/ evaporate, used as process w ater or for other on-siteapp lications such as du st control, and / or discharged to surface w ater,subject to permit requirements.

Acid drainage is a potentially severe pollution hazard associated withmining, and can be difficult to pred ict. It occurs when pyrite and othersulfide minerals, upon exposure to oxygen and water, oxidize to createferrous ions and sulfuric acid . Catalyzed by bacteria, the ferrou s ionsreact further with oxygen, producing hydrated iron oxide, known as"yellowboy ." This combination of yellowboy and su lfu ric acid may

contaminate surrounding soil, groundwater, and surface water,prod ucing wa ter with a low pH . When this reaction occurs within amine it is called Acid Mine Dra inage (AMD). When it occur s in wasterock and tailings piles it is often known as Acid Rock Drainage (ARD),although AMD is the most widely used term for both.

AMD is a significant problem at many abandoned mine sites: a 1993survey by the U.S. Forest Service ( Acid Mine Drainage from Mines on


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National Forests, A Management Challenge ) estimates that 5,000 to 10,000miles of d omestic streams and rivers are impacted by acid d rainage. Aciddr ainage can lower the pH of surroun d ing water, making it corrosive andunable to support many forms of aquatic life; vegetation growing alongstreams can also be affected. Mine water can also carry toxic, metal-

bearing sediment into streams, which can kill waterborne plant andanim al species. In extreme cases, acid d rainag e can kill all livingorganisms in nearby streams. Hu man s may also increase disease risks byconsum ing d rinking w ater and fish tissue w ith a heavy m etal content.

Accord ing to the 1994 Technical Document/ Background for NEPA Reviewers: Non-Coal Mining Operations , prepared by EPA's Office of Solid Waste(OSW), acid drainage can pose significant threats to surface andgroundwater quality and resources during active mining and for decadesafter opera tions cease. Although mines that began op erating after 1978are required to treat their effluent water, the need for water treatmentmay p ersist for decades after mining operations have ceased. Aband onedmines and refuse piles can produce acid damage for over 50 years.According to EPA's hardrock mining strategy framework, for example,"negative changes in geochemistry over time can occur when thematerials' environment changes (e.g., going from a redu cing environmentto an oxidizing one) or buffering capacity is exceeded (such as when thetotal neutra lizing capacity of a rock mass is exceeded by acid g eneration).When these conditions are present, a facility can close in fullenvironmental compliance, only to have a severe problem show upd ecad es later." Because remed iating acid d rainage is so dam aging andcostly, predictive tools, design performance, financial assurance, andmonitoring have become increasingly imp ortant.

Acid leaching operations are an ad d itional source of w ater pollution. Theleaching process itself resembles acid drainage, but it is conducted usinghigh concentrations of acids to extract metals from ore. Since acidleaching prod uces large volum es of metal-bearing acid solutions, it is vitalthat leach dumps and associated extraction areas be designed to preventreleases. Most environmen tal d amage associated w ith acid leaching iscaused by leakage, spillage, or seepage of the leaching solution at various

stages of the process. Potential problems include: seepage of acidsolutions through soils and liners beneath leach piles; leakage fromsolution-hold ing pon ds an d transfer channels; spills from rup tured pipesand recovery equipm ent; pond overflow caused by excessive ru noff; andrup tures of dam s or liners in solution-holding p ond s. Cyanide leachingsolution processes carry a similar potential for damage as a result of leakages, spills, overflows, and rup tures.


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Solution ponds associated with leaching operations are potential sourcesof acid and metal releases to ground and surface w ater. Pond s associatedwith precious metal leaching operations and newer copper facilities aregenerally lined with synthetic materials (although liners are oftensusceptible to failure). At old er copp er sites, solution pond s may be

un lined or lined only w ith natu ral mater ials. Leakage, run-off fromprecipitation, and the like, may cause contamination of ground andsurface waters.

A ir Substantial air pollution can occur at mining sites during excavation andtransp ortation. Fugitive d ust may be a significant prob lem at some sites,d epend ing on site cond itions and m anagem ent practices, and is created atmany stages of the mining process. The inheren t toxicity of the du stdepends on the proximity of environmental receptors and type of orebeing mined; high levels of arsenic, lead, and radionuclides inwindblown dust tend to pose the greatest risk, according to EPA's 1995hard rock mining framework strategy. Sources of d ust may be from roadtraffic in th e mine p it and surroun d ing areas, rock crushers located in p itsand in mills, and tailings pond s.

Dust control methods aim to reduce amounts and concentrations of dustprod uced and to minimize hu man exposure to remaining du st. The mostimportant element of dust control at underground mines is a properlyd esigned ventilation system. Water sprays are also used d uring oretransportation an d crushing, and can greatly red uce d ust levels at the site.

Dust sup pressants, such as lignin sulfonates and magn esium chloride, canstabilize solid piles or tailing areas that might otherwise become airbornein wind y cond itions. After mine closure, revegetation or other stabilizingmethod s may be used for d ust control.

Exhaust fumes from diesel engines and blasting agents may also beserious hazards at un d erground m ines. These exhausts prod uce carbonmonoxide and nitrogen oxide gas, which collect in underground areas.Ventilation and monitoring are important steps taken to reduce thepotential harm these fum es may cause workers.

The following exhibit, derived from EPA's OSW 1994 Technical Document /Background for NEPA Reviewers: Non-Coal Mining Operations ,describes the various measures mining operators may take to mitigatepotential environmental impacts of waste products generated throughd ifferent ph ases of the extraction and beneficiation processes.


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Exhibit 16Potential Mine Waste Mitigation Measures

Mining Waste Product Mitigation Measures

Extraction - MineWorkings

Evaporation and re-use of mine water in processing operations Run-on and runoff control measures, such as berms and ditches Neutralization/ precipitation or other treatment pr actices prior to

discharges Clean-up of blasting residuals Provide for post-closure mine water m anagement Monitor d ischarges and surface water quality Site mine water containment u nits to minimize potential for

surface water rechargeExtraction - Waste Rock / Overburden

Backfill into dry m ine workings with w aste rock Maximize use of overburden in reclamation Collect and monitor seepage, drainage, and ru noff

Segregate and cover reactive waste rock with non-reactivema terials where ARD is observed

Use non-reactive waste rock for on-site construction Provide for adequate d um p d rainage to minimize potential for

slope failur e Conduct baseline sur face w ater m onitoring; continue monitoring

throughout operation and post-closure Use run -on controls to minimize potential for infiltration

Beneficiation - TailingsImpoundments

Design unit to contain m aximum reasonable storm event Consider natu ral and/ or synthetic liners for units located in

dr ainages; consider liners for any seepage/ ru noff collectionsumps/ ditches

Maximize the reclaim/ reuse of tailings water Limit mill reagents to least extent necessary Provide adequ ate drainage of berms Includ e second ary containment of tailings pipelines Continue ARD testing throughout operations and closure Collect and treat runoff/ seepage from outer slopes of

impoundment


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Exhib it 16 (cont'd)Potential Mine Waste Mitigation Measures

Mining Waste Product Mitigation Measures

Beneficiation - Coppe rDu mp Leach Ope rationsand S X/EW Plants, Gol dHeap Leaching

Design du mp leach units to fully drain to collection areas Ensure that collection, pregnant solution, and raffinate ponds are

designed to contain up to the maximum reasonable storm event;line process ponds, heap leach pads, and conveyances

Install leachate d etection and collection systems und er p onds andheaps; construct seepage ponds d owngrad ient of ponds, heaps,and dumps

Recycle process w ater Lime neutralization or w etlands treatment of acid d rainage Provide secondary containment for solution pipes to m inimize

impacts from pipe failures/ spills Collect and treat d rainage that occurs after closure, as necessary

Perform baseline groundw ater monitoring and conductgroundw ater quality monitoring during operations and p ost-closure; monitor post-closure discharges and downstreamsurface w ater qu ality

Detoxification of heaps, du mps, and any spent solutions toreduce cyanide, acidity, and metal loadings

Biological treatment for cyanides, nitrates, and hea vy metalsBeneficiation - CyanideLeaching Operations

Where possible, do not locate leaching operations in or neardrainages

Ensure that pregnant and barren ponds and ditches are designedto contain all solution flows and any ru noff up t o the maximu mreasonable storm event

Use double liners and leak detection systems for all heaps,pond s, and dr ainage ditches

Test d etoxified materials prior to disposal or closure to ensurecyanide levels are reduced

Collect and test seepage and runoff from spent ore piles; treatrunoff/ seepage as necessary; perform dow nstream w ater qualitymonitoring

Beneficiation - In SituMining

Ensure proper prod uction well installation/ completion to avoiduncontrolled solution releases; provide for adequate wellabandonment

Perform a detailed characterization of the site hydrogeology toguide d esign of recovery systems and determine p otential forreleases

Carefully monitor pu mp ing pressures of solutions entering andleaving deposits to assure tha t solutions are not migrating intogroundwater

Line surface collection systems and prov ide for leak detection;design collection systems to contain maximu m volum es of leaching solutions and runoff/ precipitation/ snow melt


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Because proposed mining activities may also impact aquatic resources,vegetation, and wildlife, EPA suggests the following potential mitigationmeasu res for use at mine sites:

Exhibit 17Ecosystem Mi tigation Measures

Employ sediment retention structures to minimize amount of sedimentmigrating off-site

Employ spill prevention and control plans to minimize discharge of toxic/ hazard ous materials into water bodies

Site roads, facilities, and structures to minimize extent of physical disturbance Avoid construction or new disturbance during critical life stages Reduce the chance of cyanide poisoning of waterfowl and other wildlife by

neutr alizing cyanide in tailings pond s or by installing fences and netting to keepwildlife out of ponds

Minimize use of fences or other such obstacles in big game migration corridors;if fences are necessary, use tunnels, gates, or ramps to allow passage of theseanimals

Use "raptor proof" designs on power poles to prevent electrocution of raptors Use buses to transport employees to and from mine from outer parking areas to

minimize animals killed on mine-related roadways Limit impacts from habitat fragmentation, minimize number of access roads,

and close and r estore roads no longer in use Prohibit use of firearms on site to minimize poaching


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IV. W ASTE R ELEASE P ROFILE

This section provides a general overview of the waste release activitiesand issues common to the metal min ing ind ustry . Unlike facilitiescovered by SIC codes 20 through 39 (manufacturing facilities), metal

mining (extraction and beneficiation) facilities are not required by theEmergency Planning an d Commu nity Right-to-Know Act to report to theToxic Release Inven tory (TRI). EPA is consid ering expand ing TRIreporting requirements in the future, including participation of previously exemp t ind ustries such as metal min ing. Because TRIreporting is not required in the metal mining industry, other sources of waste release d ata hav e been iden tified for this profile.

IV.A. Waste Release D ata for the Metal Mining Industry

In 1994 EPA's OSW studied the unpermitted mining waste releases andenvironmen tal effects for nine States: Arizona, California, Colorado,Idaho, Montana, Nevada, New Mexico, South Carolina, and SouthDakota. Researchers examined State records to d ocument waste releaseevents for various types of mines throu ghou t each State. These releasesgenerally w ere not authorized un d er existing p ermits or regulations, andtherefore should not be considered "accepted," "standard," or "typical"w aste outp uts of metal mining facilities. Rather, the da ta presented belowoffer a picture of representative unpermitted mining release events, andof the magnitude of these events in many Western States, where most

metal mining facilities are located . It shou ld be noted th at most of thesereleases were pr operly mitigated by the associated m ining compan ies.

The release information p resented below is categorized by mineral type,and is derived from the Mining Waste Releases and Environmental EffectsSummaries reports prepared for OSW (see "References" for furtherinformation). Release d ata are presented in the un its of measurem entreported by each State and are therefore not standard ized. Iron ore is notrepresented in the data because all U.S. iron ore mining occurs outside of the States selected for the survey. Note that the common types of waste

released pose the greatest potential for polluting water sources, as statedelsewhere in this profile. Breaches of tailings imp oun dmen ts, andsubsequ ent spills of tailings, are not includ ed in the d ata.

Copper As evidenced in the following exhibit, the most prevalent waste releaseevents related to copper mining involve leachate or process wastewater,


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reflecting the predomina nt extraction meth od for this ore. Acid MineDrainage is a significant release associated with abandoned copper mines.

Exhibit 18Coppe r-Related Waste Releases

Site Waste ReleasedRelease

Event YearCyprus Miami Mine,Claypool, AZ

Copper leachate (amount u nknown)Waste water (amount unknow n)Non-potable water (37,000 gallons)

(min 185, 000 gallons)

19901980, 85, 8619901989

Magma Copper, Miami Tailin gsReprocessi ng Pit and CopperCities Pit, Miami, AZ

Pregn ant leach (5000-10000 gallons)Slur ry (15,600 gallons, 35,000 gallons,

1000-2000 gallons ,216,600 gallons)

Recycle (1,320 gallons)Effluent (amount unknow n)

198419891991199119891991

Oracle Ridge Mine,Pima County, AZ

Copp er concentrate (100 poun ds)Process water (5000 gallons)

19911991

ASARCO, Ray Mine s,Gila County, AZ

Diesel fuel (amount unknown)PCB, dielectric fluid (10 gallons)Sulfuric acid (20 tons)Gasoline (amount un known)Acidic water ( amoun t unknow n)Cooling tower blowdown (4340m^3/ day)Sulfur dioxide (amoun t unknow n)

1989198919891989198519851988

Sierrita Mine and Mil l, CyprusMinerals Corp.,Pima County, AZ

Process water (1 gallon/ min)Pregnant leachate (amount unknow n)

1987extended

Chino Mines, NM Heavy m etals and sulfuric acidAcidic w ater (16,200 gallons)

(2 million gallons)

extended19861988

Tyearone Mine, NM TDS and sulfu ric acid from tailings (4,270 acrefeet per year)

1978-89

Montana Resources, Inc.Butte, MT

Leach (amount unknown) 1986

Bully Hill Mine, Redding, CA Acid mine drainage (30 gallons/ min) since 1927Penn Mine, New Penne Mines,Inc., Campo Seco, CA

Acid mine d rainageLeaching of heavy m etals (no know n flow rate)

since 1955

Walker Mine, Calicopia Corp.,Plumas County, CA

Acid mine d rainageHeavy m etals (no known flow rate)

since 1941

Mammoth, Keystone & Stow ellMines , Shasta County, CA

Acid m ine d rain age (100-275 g allo ns/ m in ) exten d ed tim eperiod

Red Ledge Mine, N V See Gold and SilverArimetco Facility,ArimetcoInc./Copper Tek Corp.,Lyon County, N V

Acid leach (amount unknow n)Pregnant solution (2000 gallons)

1989-911990

Ne vada Moly Project, CyprusTononpah Mining,Tononpah, N V

Process solution (amount unknown)Mercu ry (5.783 kg)

19891990

Rio Tinto Mine, U S ForestService, Elko County, N V

Acid (amount unknown) extended


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Lead and Z inc

Because lead an d zinc are often m ined as a by prod uct of other primaryores (copp er or silver, for examp le), less d ata is available concerningreleases specific to lead and zinc mining p rocesses. Unless a mine

opera tes exclusively as a lead/ zinc operation, waste releases associatedwith these minerals are generally subsum ed in the p rimary ore categoryand is includ ed in the "Gold an d Silver" d ata.

Exhibit 19Lead and Zinc - Related Waste Releases

Site Waste ReleasedRelease

Event YearBlack Cloud Mi ne, Res-ASARCO Joint Venture, LakeCounty, CO

Copper sulfate (2 gallons, 10 gallons, 50 gallons,

amount unknown)

Water and sediments (amount unknow n)Acid leak (amount unknow n)

1987

1987

1983extended

Taylor/Ward Project ,WhitePine County, NV

Lead only, see gold and silver

Central Valle y of CA Zinc only, see gold a nd silver

Red Ledge M ine, ID Zinc only, see gold a nd silver

Montana Tunnels Mine, MT See gold a nd silver

Lucky Friday Mi ne, Mu llan,ID

See gold a nd silver

Taylor/Ward Project, A ltaGold Co., White PineCounty, NV

Lead only, see gold and silver

Gold and Silver

As might be expected from the pred ominant ben eficiation m ethodsassociated w ith gold an d silver mining, release of leachate solutions(pregn ant, p rocess, barren, etc.) is by far the m ost comm on typ e of releasefor these ores, followed b y release of cyanid e, a comm on treatm entsolution. Release of cyanide is reported as presented in State files and ispresum ed to be released in solution form. Acid Mine Drainag e is alsoproblematic for gold and silver ore mining.


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Exhibit 20 Gold- and Silve r -Related Waste Releases

Site Waste Released

ReleaseEvent Year

Ame rican Girl Mine, AmericanGirl Mini ng Co., ImperialCounty, CA

Pregnant solution (1700 gallons)Process solution (4320-8640 gallons )

Barren solution (5000 gallons)

19871988

1989Carson Hil l Gol d Mine,Western Mini ng Co., CalaverasCounty, CA

Pregnant leach solu tion (91,450 gallons) 1989

Goldfields Operating Co.,Mesquite, CA

Leaching solution (amount unknow n)

(770, 50, 2520, 33, 26 gallon s)Pregnant solution (4000 gallons)

(52 gallons)

1986

19901989

1990

Golds tripe Project, PlumasCounty, CA

Leaching solution (amount unknow n)

Residue solution (amount unknow n)

1986

1986-87

Gray Eagle Min e, N oranda,Siskiyou County, CA

Slurry (15 and 30 gallons/ min)

(1000-1500 gallons )(19,100 gallons)

Untreated wa ter (2-3 gallons/ min for hou rs)

1983

19831986

1989

Jamestow n Mine , SonoraMining Corp., TuolumneCounty, CA

Flotation solution (500 gallons)

Reagents (2,700 gallons)Process w ater (1000 and 1500 gallons)

Soda ash solution (3000 gallons)

Supernatant (20 gallons/ min)Concentrate (amount unknown, 10 tons, amount

unknown)

1987

19871989, 90

1990

19871988, 90, 91

Kanaka Creek Joint Venture,Alleghany, CA

Effluent w ith arsenic (28 gpm) 1989

McLaughlin Mine, HomestakeMini ng Co., Napa & YoloCounties