EXTRACTION AND BENEFICIATION.pdf

EPA 530-R-94-013

NTIS PB94-170-305

T ECHNICAL R ESOURCE D OCUMENT

EXTRACTION AND BENEFICIATION OF

ORES AND MINERALS

VOLUME 2

GOLD

August 1994

U.S. Environmental Protection Agency

Office of Solid Waste

Special Waste Branch

401 M Street, SW

Washington, DC 20460

Technical Resource Document: Gold

DISCLAIMER AND ACKNOWLEDGEMENTS

This document was prepared by the U.S. Environmental Protection Agency

(EPA). The mention of company or product names is not to be considered

an endorsement by the U.S. Government or the EPA.

This Technical Resource Document consists of five sections. The first

section is EPA's Profile of the gold industry; the remaining four sections are

Site Visit Reports from site visits conducted by EPA. The Profile Section

was distributed for review to the U.S. Department of the Interior's Bureau

of Mines and Bureau of Land Management, the U.S. Department of

Agriculture's Forest Service, the Western Governors Association, the

Interstate Mining Compact Commission, the American Mining Congress,

and Environmental Public Interest Groups. Summaries of the comments

and EPA's responses are presented as an appendix to the Profile Section.

The Site Visit Report Sections were reviewed by individual company, state,

and Federal representatives who participated in the site visit. Comments

and EPA responses are included as Appendices to the specific Site Visit

Sections. EPA is grateful to all individuals who took the time to review

sections of this Technical Resource Document.

The use of the terms "extraction," "beneficiation," and "mineral processing"

in the Profile section of this document is not intended to classify any waste

streams for the purposes of regulatory interpretation or application. Rather,

these terms are used in the context of common industry terminology.

Technical Resource Document: Gold

TABLE OF CONTENTS

Page

1.0 M INING I NDUSTRY P ROFILE : G OLD .................................................... 1-1

1.1 INTRODUCTION . ........................................................... 1-1

1.2 ECONOMIC CHARACTERIZATION OF THE INDUSTRY ......................... 1-3

1.3 ORE CHARACTERIZATION . ................................................. 1-6

1.3.1 Types of Gold Ore Deposits ........................................... 1-7

1.3.1.1 Sediment-Hosted Disseminated Gold ............................ 1-7

1.3.1.2 Volcanic-Hosted Epithermal Deposits ........................... 1-7

1.3.1.3 Porphyry Copper-Related Deposits ............................. 1-7

1.3.1.4 Greenstone Gold Quartz Vein Deposits .......................... 1-8

1.3.2 Mineral Content ..................................................... 1-8

1.4 GOLD EXTRACTION AND BENEFICIATION PRACTICES ....................... 1-11

1.4.1 Extraction Methods ................................................. 1-11

1.4.1.1 Surface Mining ............................................ 1-13

1.4.1.2 Underground Mining ........................................ 1-14

1.4.2 Beneficiation Methods ............................................... 1-14

1.4.2.1 By-Product Gold (Flotation) .................................. 1-14

1.4.2.2 Gravity Concentration ....................................... 1-16

1.4.2.3 Amalgamation ............................................. 1-16

1.4.2.4 Cyanidation ............................................... 1-17

1.5 WASTES AND OTHER MATERIALS ASSOCIATED WITH GOLD EXTRACTION

AND BENEFICIATION ...................................................... 1-39

1.5.1 Extraction and Beneficiation Wastes and Materials ........................ 1-40

1.5.1.1 RCRA Defined Wastes ...................................... 1-40

1.5.1.2 Materials ................................................. 1-43

1.5.2 Waste and Materials Management ...................................... 1-43

1.5.2.1 RCRA Units .............................................. 1-44

1.5.2.2 Non-RCRA Units .......................................... 1-45

1.6 ENVIRONMENTAL EFFECTS ............................................... 1-46

1.6.1 Ground Water/Surface Water ......................................... 1-46

1.6.1.1 Acid Generation ........................................... 1-46

1.6.1.2 Mine Dewatering ........................................... 1-47

1.6.1.3 Release of Cyanide Solution From Active Heap Leach Units ........ 1-47

1.6.1.4 Release From Heap Leach Piles During and After Closure

(Reclamation) ............................................. 1-48

1.6.2 Soil .............................................................. 1-49

1.6.2.1 Land Application of Spent Cyanide Solution ..................... 1-49

1.6.2.2 Detoxification of Cyanide .................................... 1-49

1.6.3 Air ............................................................... 1-51

1.6.3.1 Fugitive Dust .............................................. 1-51

1.6.4 Damage Cases ..................................................... 1-51

1.6.4.1 National Priorities List ...................................... 1-51

1.6.4.2 304(l) Sites ............................................... 1-52

1.7 CURRENT REGULATORY AND STATUTORY FRAMEWORK . .................. 1-53

1.7.1

Environmental Protection Agency Regulations ............................ 1-53

1.7.1.1

Resource Conservation and Recovery Act ....................... 1-53

1.7.1.2

Clean Water Act ........................................... 1-55

1.7.1.3

Clean Air Act

............................................. 1-57

1.7.2

Department of Interior ............................................... 1-59

Technical Resource Document: Gold

1.7.2.1 Bureau of Land Management ................................. 1-59

1.7.2.2 National Park Service and Fish and Wildlife Service ............... 1-61

1.7.3 Department of Agriculture; Forest Service ............................... 1-61

1.7.4 Army Corps of Engineers ............................................. 1-62

1.7.5 STATE REGULATIONS ............................................ 1-63

1.7.5.1 Nevada ................................................... 1-63

1.7.5.2 South Carolina ............................................. 1-66

1.8 REFERENCES ............................................................. 1-69

2.0 S ITE V ISIT R EPORT : B REWER M INE .................................................... 2-1

2.1 INTRODUCTION ............................................................ 2-1

2.1.1 Background ........................................................ 2-1

2.1.2 General Facility Description ........................................... 2-2

2.1.3 Environmental Setting ................................................ 2-4

2.1.3.1 Surface Water .............................................. 2-4

2.1.3.2 Geology ................................................... 2-5

2.1.3.3 Hydrogeology .............................................. 2-6

2.2 FACILITY OPERATIONS ..................................................... 2-7

2.2.1 Mining Operations ................................................... 2-7

2.2.2 Beneficiation Operations .............................................. 2-8

2.2.3 Chemical Usage .................................................... 2-12

2.3 MATERIALS AND WASTE MANAGEMENT ................................... 2-13

2.3.1 Mine Pit and Water ................................................. 2-13

2.3.2 Waste Rock Pile .................................................... 2-14

2.3.3 Leach Pads and Spent Ore ............................................ 2-15

2.3.4 Sediment Pond ..................................................... 2-18

2.3.5 Pad 6 Overflow Pond ................................................ 2-20

2.3.6 Solution Ponds ..................................................... 2-21

2.3.7 Other Wastes and Materials ........................................... 2-23

2.4 REGULATORY REQUIREMENTS AND COMPLIANCE ......................... 2-24

2.4.1 South Carolina Department of Health and Environmental Control ............ 2-24

2.4.1.1 Bureau of Water Pollution Control ............................. 2-24

2.4.1.2 Bureau of Air Quality Control ................................ 2-30

2.4.2 Land Resources Commission .......................................... 2-37

2.4.2.1 Division of Mining and Reclamation Mining Permit 671 ........... 2-37

2.4.2.2 Engineering Division Dam Construction and Repair Permits ........ 2-39

2.4.3 Other Regulatory Agencies and Permits ................................. 2-39

2.5 REFERENCES ............................................................. 2-40

3.0 S ITE V ISIT R EPORT : C OLOSSEUM M INE ................................................. 3-1

3.1 INTRODUCTION ............................................................ 3-1

3.1.1 Background ........................................................ 3-1

3.1.2 General Facility Description ........................................... 3-2

3.1.3 Environmental Setting ................................................ 3-4

3.1.4 Geology ........................................................... 3-6

3.1.5 Surface Water ....................................................... 3-8

3.1.6 Ground Water ....................................................... 3-9

3.2 FACILITY OPERATIONS .................................................... 3-13

3.2.1

Mining

........................................................... 3-13

3.2.2

Beneficiation

...................................................... 3-15

3.2.2.1

Crushing and Grinding ...................................... 3-15

3.2.2.2

Carbon-In-Pulp ............................................ 3-19

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Technical Resource Document: Gold

3.2.2.3 Carbon Stripping ........................................... 3-19

3.2.2.4 Electrowinning, Electrorefining, and Smelting .................... 3-20

3.3 MATERIALS AND WASTE MANAGEMENT ................................... 3-22

3.3.1 Waste Rock Piles ................................................... 3-22

3.3.2 Low-Grade Stockpile ................................................ 3-24

3.3.3 Open Pits ......................................................... 3-24

3.3.4 Cyanide Destruction Reactor .......................................... 3-25

3.3.5 Tailings Impoundment ............................................... 3-25

3.3.6 Other Wastes and Materials Reused/Recycled ............................ 3-31

3.4 REGULATORY REQUIREMENTS AND COMPLIANCE ......................... 3-32

3.4.1 Bureau of Land Management .......................................... 3-32

3.4.2 California Department of Conservation, Division of Mines and Geology ....... 3-33

3.4.3 California Regional Water Quality Control Board, Lahontan Region .......... 3-34

3.4.3.1 Cyanide Detoxification Facility (INCO) ......................... 3-35

3.4.3.2 Tailings Impoundment ...................................... 3-35

3.4.3.3 Waste Rock Piles ........................................... 3-36

3.4.3.4 General Requirements ....................................... 3-36

3.4.4 Air Pollution Control District, San Bernardino County ..................... 3-39

3.4.5 Other Permits ...................................................... 3-39

3.5 REFERENCES ............................................................. 3-42

4.0 S ITE V ISIT R EPORT : N ERCO M INERALS C RIPPLE C REEK .................................... 4-1

4.1 INTRODUCTION ............................................................ 4-1

4.1.1 Background ........................................................ 4-1

4.1.2 General Facility Description ........................................... 4-2

4.1.3 Environmental Setting ................................................ 4-6

4.1.3.1 Climate ................................................... 4-6

4.1.3.2 Surface Water .............................................. 4-6

4.1.3.3 Ground Water .............................................. 4-7

4.1.3.4 Vegetation ................................................. 4-8

4.1.3.5 Soils ...................................................... 4-8

4.1.3.6 Geology ................................................... 4-8

4.2 FACILITY OPERATIONS .................................................... 4-10

4.2.1 Mining Operations .................................................. 4-10

4.2.2 Leaching Operations ................................................ 4-13

4.2.3 Gold Recovery Operations ............................................ 4-15

4.3 MATERIALS AND WASTE MANAGEMENT ................................... 4-17

4.3.1 Mine Pits ......................................................... 4-17

4.3.2 Waste Rock Dump .................................................. 4-18

4.3.3 Heap Leach Pads and Ponds, Permit 77-367 (Globe Hill Projects) ............ 4-19

4.3.3.1 Globe Hill Pad and Ponds .................................... 4-20

4.3.3.2 Forest Queen/2A Heap Leach Pad(s) and Pond(s) ................. 4-22

4.3.4 Victor Tailings Piles and Previous Vat Leach Operation (Permit 81-134) ....... 4-24

4.3.5 Ironclad Heap Leach Pads and Ponds (Permit 81-134) ...................... 4-30

4.3.5.1 Heap Leach Pads ........................................... 4-32

4.3.5.2 Solution Ponds ............................................ 4-39

4.3.5.3 Wastes and Other Materials Managed by Nerco .................. 4-40

4.4 OTHER MAJOR CRIPPLE CREEK OPERATIONS ............................... 4-43

4.4.1 Carlton Mill (Pads 1 and 2) ........................................... 4-43

4.4.2 Victory Project (Pads 3 and 4) ......................................... 4-45

4.4.3 '76 (Bull Hill) Project ................................................ 4-48

4.5 REGULATORY REQUIREMENTS AND COMPLIANCE

......................... 4-51

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