Inorganic Arsenic Emissions from High-Arsenic Primary Copper Smelters: Background Information for Proposed Standards


                                   EPA-450/3-83-009a
    Inorganic Arsenic Emissions from
High-Arsenic Primary Copper Smelters -
         Background  Information
         for Proposed Standards
             Emission Standards and Engineering Division
             U.S ENVIRONMENTAL PROTECTION AGENCY
               Office of Air, Noise, and Radiation
             Office of Air Quality Planning and Standards
             Research Triangle Park, North Carolina 27711

                     April 1983

-------
This report has been reviewed by the Emission Standards and Engineering Division of the Office of Air Quality Planning
and Standards, EPA, and approved for publication. Mention of trade names or commercial products is not intended to
constitute endorsement or recommendation for use. Copies of this report are available through the Library Services
Office (MD-35), U.S. Environmental Protection Agency, Research Triangle Park, North Carolina 27711; or, for a fee, from
the National Technical Information Services, 5285 Port Royal Road, Springfield, Virginia 22161.
                                    Publication No. EPA-450/3-83-009a

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                    ENVIRONMENTAL PROTECTION AGENCY
                    Background Information and Draft
                     Environmental Impact Statement
                 for Primary Copper Smelters Processing
      Feed Materials Containing 0.7 Percent or Greater Arsenic
                            Prepared by:
     R. Farmei
Director, Emission Standards and Engineering Division
U. S. Environmental Protection Agency
Research Triangle Park, NC  27711
                                                       (Date)
1.
3.
The proposed standards of performance would limit emissions of
inorganic arsenic from existing and new primary copper smelters
processing feed materials containing 0.7 percent or greater arsenic.
The proposed standards implement Section 112 of the Clean Air Act
and are based on the Administrator's determination of June 5, 1980
(45 FR 37886), that inorganic arsenic presents a significant risk
to human health as a result of air emissions from one or more
stationary source categories, and is therefore a hazardous air
pollutant.  Only one primary copper smelter, located in the State
of Washington, would be affected.

Copies of this document have been sent to the following Federal
Departments:  Labor, Health and Human Services, Defense,  Transportation,
Agriculture, Commerce, Interior, and Energy; the National  Science
Foundation;  the Council on Environmental Quality;  members  of the
State and Territorial  Air Pollution Program Administrators;  the
Association  of Local Air Pollution Control  Officials;  EPA  Regional
Administrators; and other interested parties.
The comment period for review of this document  is  60
Gene W. Smith may be contacted regarding the  date  of
period.
                                                         days.   Mr.
                                                         the  comment
4.  For additional  information contact:

    Mr. Gene W. Smith
    Standards Development  Branch  (MD-13)
    U. S. Environmental  Protection  Agency
    Research Triangle Park,  NC  27711
    telephone:   (919) 541-5624.

5.  Copies of this  document  may  be  obtained  from:

    U. S. EPA Library (MD-35)
    Research Triangle Park,  NC  27711

    National Technical  Information  Service
    5285 Port Royal  Road
    Springfield,  VA   22161

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-------
                            TABLE  OF  CONTENTS
Section
1.0  SUMMARY	    !_!
     1.1  Statutory Authority  	    1_1
     1.2  Regulatory Alternatives	•	    i_i
     1.3  Environmental Impacts  	    1_2
     1.4  Economic Impact	    1_4
2.0  THE PRIMARY COPPER INDUSTRY	    2-1
     2.1  General	    2-1
          2.1.1  Raw Materials	    2-1
          2.1.2  Process Description.  	    2-4
          2.1.3  Description of the ASARCO-Tacoma Smelter 	    2-19
     2.2  Arsenic Distribution and Emissions at ASARCO-Tacoma  .  .  .    2-21
          2.2.1  Arsenic Distribution and Process Emissions
                 at ASARCO Tacoma  .	    2-22
          2.2.2  Fugitive Arsenic Emissions at ASARCO-Tacoma.  .  .  .    2-26
     2.3  References	    2-43
3.0  CONTROL TECHNOLOGY .	    3_x
     3.1 . Alternative Control Techniques. .	      3_i
          3.1.1  Process Emission Controls	    3-1
          3.1.2  Fugitive Emission Sources and Controls 	    3-17
     3.2  Summary of Existing Control  	    3.49
          3.2.1  Process Control  Equipment at ASARCO-Tacoma ....    3-49
          3.2.2  Fugitive  Control Equipment at ASARCO-Tacoma.  .  .  .    3-51
     3.3  Performance Capabilities of Alternative Control
          Techniques  for Arsenic  and Total Particulate
          Emissions	    3.53
          3.3.1  Process Control  Systems	    3-53
          3.3.2  Fugitive  Control  Systems Evaluation	    3-68
          3.3.3  Conclusions	    3-83
     3.4  References	    3_gg

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                            TABLE OF CONTENTS
                               (continued)
Section
Page
4.0  MODEL PLANTS, REGULATORY BASELINE, AND REGULATORY
     ALTERNATIVES 	   4-1
     4.1  Model Plants	   4-1
     4.2  Baseline	   4-1
          4.2.1  Regulatory Considerations	   4-4
          4.2.2  Baseline Arsenic Emissions 	   4-11
     4.3  Regulatory Alternatives 	   4-13
          4.3.1  Process Emission Control Techniques	   4-13
          4.3.2  Fugitive Emission Control Techniques 	   4-14
          4.3.3  Regulatory Alternative I 	   4-16
          4.3.4  Regulatory Alternative II	   4-16
          4.3.5  Regulatory Alternative III 	   4-16
     4.5  References	   4-17
5.0  ENVIRONMENTAL IMPACTS	   5-1
     5.1  Introduction	   5-1
     5.2  Air Pollution Impacts of Regulatory Alternatives	   5-1
          5.2.1  Baseline Emissions 	   5-1
          5.2.2  Arsenic Emission Reductions Under the Regulatory
                 Alternatives 	   5-5
     5.3  Energy Impacts of the Regulatory Alternatives  	   5-5
     5.4  Solid Waste Impacts of the Regulatory Alternatives.  .  .  .   5-7
     5.5  Water Pollution Impacts of the Regulatory
          Alternatives	   5-8
     5.6  References	   5-10
6.0  COSTS	   6-1
     6.1  Existing Facility 	   6-1
          6.1.1  Control System	   6-1
          6.1.2  Cost Parameters	   6-2
          6.1.3  Capital and Annualized Costs 	   6-4
          6.1.4  Costs of Regulatory Alternatives  ....  	   6-7
          6.1.5  Cost-Effectiveness 	   6-7
     6.2  References	   6-9
                                   vi

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                             TABLE OF CONTENTS
                                (continued)
 Sect1on
 7.0  ECONOMIC IMPACT ................... .....   7-1
      7.1   Industry Economic Profile ................   7_1
           7.1.1   Introduction  ...............  ....   7-1
           7.1.2   Market Concentration ...............   7_2
           7.1.3   Total  Supply  ....  ...............   7_5
           7.1.4   U.S.  Total  Consumption of Copper .........   7_8
           7.1.5   Prices  ......................   7-12
      7.2   Economic Analysis  ..........  .  .........   7_^7
           7.2.1   Introduction  .  .  .............  ....   7-17
           7.2.2   Summary.  .  ....................   7_^7
           7.2.3   Methodology ....................   7_^g
           7.2.4   Maximum Percent Price  Increase  ..........   7_23
           7.2.5   Profit  Impacts  ..................    7-26
           7.2.6   Capital Availability ...............   7_32
      7.3   Socio-Economic Impact Assessment .............    7.34
           7.3.1   Executive Order 12291 ...............    7_34
           7.3.2   Regulatory Flexibility  ..............    7.35
      7.4   References ......  .  .................    7_3g
APPENDIX A - EVOLUTION OF THE BACKGROUND INFORMATION DOCUMENT  ...    A-l
APPENDIX B - INDEX TO ENVIRONMENTAL IMPACT CONSIDERATIONS  .....    B-l
APPENDIX C - SUMMARY OF TEST DATA  .................    C-l
     C.I  ASARCO-Tacoma . .....................    c_2
     C.2  ASARCO-E1 Paso. ........... ' ..........    c_6
     C.3  Anaconda. ... .....................    C-10
     C.4  Phelps  Dodge-Ajo .....................    c_12
     C.5  Phelps  Dodge-Hidalgo .............. .....    C-15
     C.6  Phelps  Dodge-Douglas ...................   C_17
     C.7  Kennecott-Magna,  Utah ..................   C-18
     C.8  Kennecott-Hayden .....................   Q_2Q
     C.9  Tamano  Smelter (Hibi  Kyodo Smelting Co.,) Japan .....   C-25
     C.10   Test Data (Tables)  ...................   c_2e
     C.ll   References .  .  .....................   C-109
                                   vii

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                            TABLE OF CONTENTS
                               (continued)

Section                                                               Page
APPENDIX D - TEST METHODS	   D-l
     D.I  Emission Measurement Methods	   D-2
     D.2  Continuous Monitoring	; . . .  .   D-7
     D.3  Performance Test Methods	   D-7
     D.4  References	   D-8
APPENDIX E - RISK ANALYSIS	   E-l
     E.I  Introduction	   E-2
          E.I.I  Overview	   E-2
          E.I.2  The Relationship of Exposure to Cancer Risk. . .  .   E-2
          E.I.3  Public Exposure	   E-5
          E.I.4  Public Cancer Risks	   E-6
     E.2  The Unit Risk Estimate for Inorganic Arsenic	   E-7
          E.2.1  The Linear No-Threshold Model for Estimation
                 of Unit Risk Based on Human Data (General)	  E-7
          E.2.2  The Unit Risk Estimate for Inorganic Arsenic . .  .   E-8
     E.3  Quantitative Expressions of Public Exposure to
          Inorganic Arsenic Emitted from High-Arsenic Primary
          Copper Smelters 	   E-10
          E.3.1  EPA's Human Exposure Model (HEM) (General) ....   E-10
          E.3.2  Pollutant Concentrations Near a Source 	   E-ll
          E.3.3  The People Living Near a Source	   E-13
          E.3.4  Exposure	   E-15
          E.3.5  Public Exposure to Inorganic Arsenic Emissions
                 from High-Arsenic Primary Copper Smelters	   E-17
     E.4  Quantitative Expressions of Public Cancer Risks
          from Inorganic Arsenic Emitted from High-Arsenic
          Primary Copper Smelters 	   E-22
          E.4.1  Methodology (General)	   E-22
                                   vm

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                       TABLE OF CONTENTS
                          (concluded)
     E.4.2  Risks Calculated for Emissions of Inorganic
            Arsenic from High-Arsenic Primary Copper
            Smelters	
E.5  Analytical  Uncertainties Applicable to the
     •Calculations of Public Health Risks Contained
     in this Appendix	 .
     E.5.1  The Unit Risk Estimate 	
     E.5.2  Public Exposure. .  .  	
E.6  References	
E-24

E-27
E-27
E-27
E-30
                              IX

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LIST OF TABLES
Table
1-1

2-1
2-2
2-3
2-4

2-5
2-6

2-7

2-8

2-9

2-10

2-11

3-1

3-2
3-3


3-4

3-5

3-6

3-7

3-8


Environmental And Economic Impacts of Regulatory
Alternatives 	
Domestic Primary Copper Smelters 	 	 	
Major Copper-Bearing Minerals 	 ......
Arsenic Input in the Feed to Domestic Copper Smelters . . .
Summary of Process Arsenic Emission Estimates for
ASARCO-Tacoma 	 . 	
Potential Sources of Fugitive Arsenic Emissions . 	
Captured Fugitive Arsenic Emissions From Calcine Discharge
From Multi-Hearth Roasters at ASARCO-Tacoma ... 	
Captured Fugitive Arsenic Emissions During Matte Tapping
From The Reverberatory Furnace at ASARCO-Tacoma . 	
Captured Fugitive Arsenic Emissions During Slag Tapping
From the Reverberatory Furnace at ASARCO-Tacoma . 	
Captured Fugitive Arsenic Emissions During Converter
Slag Return at ASARCO-Tacoma 	 	 	
Reverberatory Furnace Slag Analysis for Arsenic Content
At ASARCO-Tacoma 	 	 	
Summary of Fugitive Arsenic Emission Estimates for
ASARCO-Tacoma 	 . 	
Summary of As.Og Vapor Pressure Data and Corresponding
Arsenic Concentration at Various Temperatures .......
Arsenic Data for Hot ESP 	
Estimated Approximate Maximum Impurity Limits For
Metallurgical Off gases Used to Manufacture Sulfuric
Acid 	 	 	
Summary of Design Data for the ASARCO-Tacoma Converter
Air Curtain Secondary Hood System 	
Estimated Control Efficiencies of Existing Process
Emission Controls at ASARCO-Tacoma 	 	 	
Estimated Control Efficiencies of Existing Fugitive
Emission Controls at ASARCO-Tacoma 	 	 	
Arsenic Performance Data for the Roaster Baghouse at
ASARCO-Tacoma 	
Arsenic Performance Data for the Arsenic Plant Baghouse
At ASARCO-Tacoma 	
Page

1-3
2-2
2-3
2-5

2-25
2-27

2-30

2-32

2-33

2-35

2-40

2-42

3-2
3-6


3-13

3-43

3-51

3-52

3-54

3-56

-------
                             LIST OF TABLES
                               (continued)
Table                                                                Page

 3-9    Arsenic Performance Data for Spray Chamber/Baghouse at
        The Anaconda-Anaconda Smelter 	   3-57

 3-10   Participate Performance Data for Spray Chamber/Baghouse
        At the Anaconda-Anaconda Smelter	   3-57

 3-11   Arsenic Emissions Data at Outlet of Reverberatory Furnace
        Electrostatic Precipitator at ASARCO-Tacoma 	   3-59

 3-12   Arsenic Performance Data for Spray Chamber/Electrostatic
        Precipitator at ASARCO-E1 Paso	   3-61

 3-13   Particulate Performance Data for the Spray Chamber/
        Electrostatic Precipitator at ASARCO-E1 Paso	   3-62

 3-14   Particulate Performance Data for the Spray Chamber/
        Electrostatic Precipitator Outlet at ASARCO-E1 Paso ....   3-63

 3-15   Arsenic Performance Data for Venturi Scrubber at
        Kennecott-Hayden	   3-65

 3-16   Arsenic Performance Data for Double-Contact Acid Plant
        At ASARCO-E1 Paso	   3-67

 3-17   Arsenic Performance Data for Single-Contact Acid Plant
        At Phelps Dodge-Ajo 	   3-68

 3-18   Summary of Visible Emission Observation Data for Capture
        Systems on Fugitive Emission Sources at ASARCO-Tacoma . . .   3-70

 3-19   Air Curtain Capture Efficiencies at ASARCO-Tacoma Using
        Gas Tracer Method - January 14, 1983	   3-74

 3-20   Air Curtain Capture Efficiencies at ASARCO-Tacoma Using
        Gas Tracer Method - January 17-19, 1983 	   3-75

 3-21   Air Curtain Capture Efficiencies at ASARCO-Tacoma
        For Special Gas Tracer Injection Points - January 18-20,
        1983	   3-76

 3-22   Visible Emissions Observation Data for Converter
        Secondary Hood System During Matte Charging at the
        Tamano Smelter	   3-80

 3-23   Visible Emissions Observation Data for Blister Discharge
        At the Tamano Smelter	   3-82

 3-24   Arsenic Data for Converter Building Baghouse at
        ASARCO-E1 Paso	   3-84

 3-25   Particulate Data for Converter Building Baghouse at
        ASARCO-E1 Paso	   3-84


                                   xi

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                             LIST OF TABLES
                               (continued)
Table                                                                 Page
 4-1    Model Plant Parameters  	 4-2

 4-2    Summary of Existing Regulations Affecting Arsenic Air
        Emissions at ASARCO-Tacoma  	 4-10

 4-3    Summary of Effects of Regulatory Baseline on Arsenic
        Regulatory Alternatives for the ASARCO-Tacoma Smelter . . .  .4-12

 5-1    Process Emission Sources, Control Efficiencies, and
        Arsenic Emission Rates  	 5-3

 5-2    Fugitive Emission Factors, Capture and Collection
        Efficiencies Used to Determine Fugitive Arsenic
        Emissions	5-4

 5-3    Arsenic Emissions and Emission Reductions at ASARCO-Tacoma
        Under the Regulatory Alternatives for ASARCO-Tacoma 	 5-6

 5-4    Annual Energy Required by Air Pollution Control Equipment
        At ASARCO-Tacoma Under the Regulatory Alternatives  	 5-6

 5-5    Solid Wastes Generated by Air Pollution Control Equipment
        At ASARCO-Tacoma by Regulatory Alternative  	 5-9

 6-1    Design Parameters for the Air Curtain Secondary Hood
        And ESP for ASARCO-Tacoma	6-3

 6-2    Estimated Capital Costs for the Air Curtain Secondary Hood
        System at ASARCO-Tacoma 	 6-5

 6-3    Estimated Annual Operating Costs for the Air Curtain
        Secondary Hood and ESP System for ASARCO-Tacoma   	6-6

 6-4    Cost Bases Used in Estimating Annual Operating Costs of
        The Air Curtain Secondary Hood and ESP System for
        ASARCO, Tacoma  	 6-8
 7-1    Smelter Ownership, Production and Source Material
        Arrangements	7-3
 7-2    United States and World Comparative Trends in Copper
        Production:   1963-1981  	 7-7

 7-3    U.S. Copper Consumption	7-9

 7-4    U.S. Copper Demand By Market End Uses	7-10

 7-5    Average Annual Copper Prices  	 7-14

 7-6    Cost Increase and Maximum Percent Price Increase of Arsenic
        Controls for the High-Arsenic Primary Copper Smelter  .... 7-25

 7-7    Business Segment Return on Sales for Copper Companies  .... 7-28
                                   xn

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                             LIST OF TABLES
                               (continued)
Table                                                                Page

 7-8    Costs Increase and Maximum Percent Profit Decrease of
        Arsenic Controls for the High-Arsenic Primary Copper
        Smelter	„	7-30

 7-9    Capital Costs of Arsenic Controls for ASARCO Primary Copper
        Smelters ..... 	  7-33

 C-l    Summary of Emission Tests	C-27

 C-2    Index to Arsenic and Particulate Test Data Tables by Process
        Facility and Sample Type	C-29

 C-3    Summary of Arsenic Test Data — Roaster Baghouse Inlet,
        ASARCO-Tacoma Smelter	C-31

 C-4    Summary of Arsenic Test Data — Roaster Baghouse Outlet,
        ASARCO-Tacoma Smelter	C-32

 C-5    Summary of Arsenic Test Data -- Arsenic Kitchen Baghouse
        Inlet, ASARCO-Tacoma Smelter 	  C-33

 C-6    Summary of Arsenic Test Data — Metallic Arsenic Baghouse
        Inlet, ASARCO-Tacoma Smelter 	  C-34

 C-7    Summary of Arsenic Test Data — Arsenic Baghouse Outlet
        (Metallic and Kitchen), ASARCO-Tacoma Smelter	C-35

 C-8    Summary of Arsenic Test Data — Reverb ESP Outlet,
        ASARCO-Tacoma Smelter	C-36
 C-9    Summary of Arsenic Test Data — Calcine Discharge,
        ASARCO-Tacoma Smelter	C-37

 C-10   Summary of Arsenic Test Data -- Matte Tapping,
        ASARCO-Tacoma Smelter	C-38

 C-ll   Summary of Arsenic Test Data — Slag Tapping,
        ASARCO-Tacoma Smelter	C-39

 C-12   Summary of Arsenic Test Data ~ Converter Slag Return,
        ASARCO-Tacoma Smelter	C-40

 C-13   Summary of Arsenic Test Data — R & R ESP Inlet (Roaster),
        ASARCO-E1 Paso Smelter	C-41

 C-14   Summary of Arsenic Test Data ~ R & R ESP Inlet (Reverb-North),
        ASARCO-E1 Paso Smelter 	  C-42

 C-15   Summary of Arsenic Test Data ~ R & R ESP Inlet (Reverb-South),
        ASARCO-E1 Paso Smelter 	  C-43

 C-16   Summary of Arsenic Test Data -- R & R ESP Inlet (Total),
        ASARCO-E1 Paso Smelter	C-44
                                  xm

-------
LIST OF TABLES
  (continued)
Table
C-17

C-18

C-19

C-20

C-21

C-22

C-23

C-24

C-25

C-26

C-27

C-28

C-29

C-30

C-31

C-32

C-33

C-34

J
Summary of Arsenic Test Data — R & R ESP Outlet,
ASARCO-E1 Paso Smelter 	
Summary of Particulate Test Data — R & R ESP Inlet (Roaster)
ASARCO-E1 Paso Smelter 	 • 	
Summary of Particulate Test Data — R & R ESP Inlet (Reverb-
North), ASARCO-E1 Paso Smelter 	
Summary of Particulate Test Data — R & R ESP Inlet (Reverb-
South), ASARCO-E1 Paso Smelter 	
Summary of Particulate Test Data -- R & R ESP Inlet (Total),
ASARCO-E1 Paso Smelter 	
Summary of Particulate Test Data — R & R ESP Outlet,
ASARCO-E1 Paso Smelter 	
Summary of Arsenic Test Data -- DC Acid Plant Inlet,
ASARCO-E1 Paso Smelter 	
Summary of Arsenic Test Data — DC Acid Plant Outlet,
ASARCO-E1 Paso Smelter 	
Summary of Arsenic Test Data — Converter Building Baghouse
Inlet, ASARCO-E1 Paso Smelter 	
Summary of Arsenic Test Data — Converter Building Baghouse
Outlet, ASARCO-E1 Paso Smelter 	
Summary of Particulate Test Data — Converter Building
Baghouse Inlet, ASARCO-E1 Paso Smelter 	
Summary of Particulate Jest Data — Converter Building
Baghouse Outlet, ASARCO-E1 Paso Smelter 	
Summary of Particulate Test Data — Roaster/Reverberatory
ESP Outlet, ASARCO-E1 Paso Smelter 	
Summary of Arsenic Test Data — Calcine- Discharge Duct,
ASARCO-E1 Paso Smelter 	
Summary of Particulate Test Data — Calcine Discharge Duct,
ASARCO-E1 Paso Smelter 	
Summary of Arsenic Test Data — Matte Tapping Duct,
ASARCO-E1 Paso Smelter 	
Summary of Particulate Test Data — Matte Tapping Duct,
ASARCO-E1 Paso Smelter 	
Summary of Arsenic Test Data — Spray Chamber/Baghouse
Inlet-West, Anaconda-Anaconda Smelter 	
3age

C-45

'c-46

C-47

C-48

C-49

C-50

C-51

C-52

C-53

C-54

C-55

C-56

C-57

C-58

C-59

C-60

C-61

C-62
      XIV

-------
LIST OF TABLES
  (continued)
Table
C-35

C-36

C-37

C-38

C-39

C-40

C-41

C-42

C-43

C-44

C-45

C-46

C-47

C-48

C-49

C-50

C-51

C-52


Summary of Arsenic Test Data -- Spray Chamber/Baghouse
Inlet-East, Anaconda-Anaconda Smelter 	
Summary of Arsenic Test Data — Spray Chamber/Baghouse
Inlet (Total), Anaconda-Anaconda Smelter 	 '.....
Summary of Arsenic Test Data -- Spray Chamber/Baghouse
Outlet, Anaconda-Anaconda Smelter 	
Summary of Particulate Test Data — Spray Chamber/Baghouse
Inlet-West, Anaconda-Anaconda Smelter 	
Summary of Particulate Test Data — Spray Chamber/Baghouse
Inlet-East, Anaconda-Anaconda Smelter 	
Summary of Particulate Test Data -- Spray Chamber/Baghouse
Inlet (Total), Anaconda-Anaconda Smelter 	
Summary of Particulate Test Data — Spray Chamber/Baghouse
Outlet, Anaconda-Anaconda Smelter 	
Summary of Arsenic Test Data -- Reverberatory ESP Inlet,
Phelps Dodge-Ajo Smelter 	
Summary of Arsenic Test Data — Reverberatory ESP Outlet,
Phelps Dodge-Ajo Smelter 	
Summary of Arsenic Test Data — Converter ESP Inlet No. 1,
Phelps Dodge-Ajo Smelter 	
Summary of Arsenic Test Data -- Converter ESP Inlet No. 2,
Phelps Dodge-Ajo Smelter 	
Summary of Arsenic Test Data — Converter ESP Outlet (Acid
Plant Inlet), Phelps Dodge-Ajo Smelter 	
Summary of Arsenic Test Data -- Acid Plant Outlet,
Phelps Dodge-Ajo Smelter 	
Summary of Arsenic Test Data — Matte Tapping Hood Outlet,
Phelps Dodge-Ajo Smelter 	
Summary of Particulate Test Data — Matte Tapping Outlet,
Phelps Dodge-Ajo Smelter 	
Summary of Arsenic Test Data ~ Converter Secondary Hood
Outlet, Phelps Dodge-Ajo Smelter 	
Summary of Particulate Test Data -- Converter Secondary Hood
Outlet, Phelps Dodge-Ajo Smelter 	
Summary of Arsenic Test Data ~ Converter Secondary Hood
Outlet, Phelps Dodge-Hidalgo Smelter 	
Page

, C-63

. C-64

, C-65

. C-66

. C-67

C-68

C-69

C-70

C-71

C-72

C-73

C-74

C-75

C-76

C-77

C-78

C-79

C-80
      XV

-------
LIST OF TABLES
  (continued)
Table
C-53

C-54

C-55

C-56

C-57

C-58

C-59

C-60

C-61

C-62

C-63

C-64

C-65

C-66

C-67

C-68

C-69

C-70


Summary of Arsenic Test Data — Calcine/Roaster Fugitives
Baghouse Inlet, Phelps Dodge-Douglas Smelter 	
Summary of Arsenic Test Data — Calcine/Roaster Fugitives
Baghouse Outlet, Phelps Dodge-Douglas Smelter. . .• 	
Summary of Particulate Test Data — Calcine/Roaster Fugitives
Baghouse Inlet, Phelps Dodge-Douglas Smelter 	
Summary of Particulate Test Data -- Calcine/Roaster Fugitives
Baghouse Outlet, Phelps Dodge-Douglas Smelter 	
Summary of Arsenic Test Data — Concentrate Dryer Scrubber
Outlet, Kennecott-Magna Smelter 	
Summary of Arsenic Test Data — Acid Plant Inlet,
Kennecott-Magna Smelter 	
Summary of Arsenic Test Data — Matte Tapping Duct,
Kennecott-Magna Smelter 	
Summary of Arsenic Test Data — Slag Tapping Duct,
Kennecott-Magna Smelter 	
Summary of Arsenic Test Data -- Converter Fugitives (Full
Cycle), Kennecott-Magna Smelter 	
Summary of Arsenic Test Data — Rollout Converter Fugitives,
Kennecott-Magna Smelter 	
Summary of Arsenic Test Data — Venturi Scrubber Inlet,
Kennecott-Hayden Smelter 	
Summary of Arsenic Test Data — Venturi Scrubber Outlet,
Kennecott-Hayden Smelter 	
Summary of Arsenic Test Data — Acid Plant Outlet,
Kennecott-Hayden Smelter 	
Visible Emissions Observation Data, EPA -Method 22 — Roaster
Calcine Discharge Into Larry Cars, ASARCO-Tacoma . 	
Visible Emissions Observation Data, EPA Method 22~Matte
Tap Port and Matte Launder, ASARCO-Tacoma 	
Visible Emissions Observation Data, EPA Method 22— Matte
Discharge into Ladle, ASARCO-Tacoma 	
Visible Emissions Observation Data, EPA Method 22 — Slag
Tap Port and Slag Launder, ASARCO-Tacoma 	
Visible Emissions Observation Data, EPA Method 9— Slag
Tap and Slag Launder, ASARCO-Tacoma 	
Page

C-81

C-82

C-83

C-84

C-85

C-86

C-87

C-88

C-89

C-90

C-91

C-92

C-93

C-94

C-95

C-96

C-97

C-98
      XVI

-------
                            LIST OF TABLES
                              (concluded)
C-72


C-73


C-74


C-75


C-76


C-77



C-78


C-79


C-80


E-l


E-2


E-3


E-4


E-5
                                                               Page
Visible Emissions Observation Data3  EPA Method  22--Slag
Tapping at Slag Discharge  into Pots, ASARCO-Tacoma  	   C-99

Visible Emissions Observation Data,  EPA Method  9—Slag
Tapping at Slag Discharge  into Pots, ASARCO-Tacoma  	   C-100

Visible Emissions Observation Data,  EPA Method  22—Converter
Slag Return to Reverberatory Furnace, ASARCO-Tacoma	   C-101

Visible Emissions Observation Data,  EPA Method  9—Converter Slag
Return to Reverberatory Furnace, ASARCO-Tacoma  	   C-102

Visible Emissions Observation Data,  EPA Method  9—Blister
Discharge From Converter at the Tamano Smelter  in Japan   .  .   C-103

Summary of Average Observed Opacities for Blister Discharge
At the Tamano Smelter in Japan	C-104

Summary of EPA Method 9 Visible Emissions Data—Individual
And Total  Matte Charges to Converter Observed at the Tamano
Smelter in Japan	C-105

Summary of Visible Emissions Observation Data—Copper Blow
At the Tamano Smelter in Japan	C-106

Summary of Visible Emissions Observation Data—Slag Blow
At the Tamano Smelter in Japan	C-107

Summary of Visible Emissions Observation Data—Slag
Discharge at the Tamano Smelter in Japan 	   C-108

Identification of High-Arsenic Primary Copper
Smelters	„	E-18

Input Data to Dispersion Model  for ASARCO-Tacoma
Smelter (Baseline Control) 	 	   E-19

Total Exposure and Number of People Exposed
(High-Arsenic Primary Copper Smelters) 	   E-20

Public Exposure for High Arsenic Copper Smelters
as Produced by the Human Exposure Model	E-21
Maximum Lifetime Risk and Cancer Incidence for
High-Arsenic Primary Copper Smelters (Assuming Baseline
Controls)	E-26
                                 xvi

-------
                             LIST OF FIGURES
Figure                                                               Page
 2-1    Primary Copper Smelter 	  2-6
 2-2    Primary Copper Smelting Process	2-7
 2-3    Calcine Roaster	2-9
 2-4    Reverberatory Smelting Furnace 	  2-12
 2-5    Copper Converter 	  2-16
 2-6    ASARCO-Tacoma Arsenic Material Balance 	  2-23
 2-7    Fugitive Emission Sources at Primary Copper Smelters ....  2-28
 3-1    Arsenic Trioxide Vapor Pressure and Saturated Vapor
        Concentration with Temperature 	  3-3
 3-2    Contact Sulfuric Acid Plant	3-15
 3-3    Types of Exhaust Hoods	3-20
 3-4    Uses of Air Curtains	3-21
 3-5    Spring-Loaded Car Top and Ventilation Hood, ASARCO-
        Hayden	3-24
 3-6    Matte Tapping Fugitive Control System (Plan View),
        ASARCO-Tacoma	3-26
 3-7    Matte Tapping and Ladle Hoods	3-27
 3-8    Launder Cover	3-29
 3-9    Slag Tapping Fugitive Control System  (Plan View),
        ASARCO-Tacoma	3-30
 3-10   Typical Converter Fixed Secondary Hood 	  3-33
 3-11   Conceptual Design for Converter Mechanical Secondary
        Hood System	3-34
 3-12   Converter Air Curtain Control System  	  3-37
 3-13   Converter Air Curtain Secondary Hood, Ohahama and
        Naoshima Smelters	3-38
 3-14   Air Curtain System  at the Tamano Smelter	3-40
 3-15   Controlled Airflow  from a Heated Source   	  3-44
 3-16   Uncontrolled Airflow from a  Heated  Source	3-44
 3-17   Anode  Furnace Movable Hood	3-47
 3-18   SFg Tracer Injection Locations  	  3-72
 3-19   Tracer Injection  Test  Ports	'	3-73
 3-20   Control Device Arsenic Collection Efficiencies  	  3-86
 E-l    Tacoma Plant Configuration  	  E-14
                                  xv i i i

-------
                          1.0  SUMMARY

1.1  STATUTORY AUTHORITY
     National emission standards for hazardous air pollutants are
established in accordance with Section 112(b)(l)(B) of the Clean Air
Act (42 U.S.C. 7412), as amended.  Emission standards under Section 112
apply to new and existing sources of a substance that has been listed
as a hazardous air pollutant.  This study examines inorganic arsenic
emission sources at primary copper smelters which process feed material
with an annual average inorganic arsenic content of 0.7 percent by
weight or greater.  This category of primary copper smelters is defined
as "high arsenic throughput smelters."  The only existing primary copper
smelter in the high arsenic throughput smelter category is owned and
operated by ASARCO, Incorporated (ASARCO) and located in Tacoma,
Washington.  No other existing smelters are expected to increase the
annual average inorganic arsenic content of their feed materials to or
above 0.7 percent and'no new smelters are projected to be built during
the next 5 years.  For this reason, only the ASARCO smelter located in
Tacoma, Washington (hereafter referred to as "ASARCO-Tacoma"), is
analyzed in this document with respect to the environmental, energy,
and economic impacts of regulating the high arsenic throughput smelter
category.  Primary copper smelters which process feed materials with an
annual average arsenic content less than 0.7 weight percent are analyzed
in the document, Arsenic Emissions from Low Arsenic Throughput Primary
Copper Smelters - Background Information for Proposed Standards (EPA-
450/3-83-010a).
1.2  REGULATORY ALTERNATIVES
     Based on consideration of the control techniques available, three
regulatory alternatives were developed for application to arsenic
emissions from the ASARCO-Tacoma smelter.
                                  1-1

-------
      Regulatory Alternative  I corresponds to the baseline level of
 control.   No  additional controls beyond the controls already in place
 at  the ASARCO-Tacoma smelter to comply with existing regulations (e.g.,
 Washington State  implementation plan, OSHA inorganic arsenic worker
 exposure  standard) would  be  required.  Therefore, no national emission
 standard  would be established for arsenic emissions from high arsenic
 throughput smelters.
      Regulatory Alternative  II represents control of fugi.tive arsenic
 emissions  from converter  operations at the ASARCO-Tacoma smelter.  This
 alternative is based on capture of the fugitive emissions using a
 secondary  hood with a horizontal air curtain.  The captured secondary
 emission  would be vented  to  a baghouse or equivalent control device for
 collection.
      Regulatory Alternative  III would require that arsenic emissions
 from  the  ASARCO-Tacoma smelter be reduced to zero.  To accomplish this
 alternative, the ASARCO-Tacoma smelter would be forced to process ores
 which were virtually free of arsenic content.  Implementation of
 Regulatory Alternative III would therefore result in closure of the
 ASARCO-Tacoma smelter.
 1.3   ENVIRONMENTAL IMPACTS
     To evaluate environmental  impacts, estimates were made of the air
 quality, water, solid waste, and energy impacts which would result from
 each  of the regulatory alternatives.  Table 1-1 summarizes the
 environmental impact assessments.
     Regulatory Alternative  I (baseline case) would not change the
 existing air and nonair quality environmental impacts of operations at
 the ASARCO-Tacoma smelter.  Total arsenic emissions from the smelter
 would remain at the current  level of 282 megagrams (Mg) (311 tons)  per
year, and  there would be  no energy or economic impacts attributable
 to this alternative.
                                  1-2

-------





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     Regulatory Alternative II would reduce total  arsenic  emissions
from the ASARCO-Tacoma smelter by 110 Mg (121 tons)  per year  to  a  level
of 172 Mg (189 tons) per year.  The amount of collected particulate
matter containing arsenic would be approximately  11  gigagrams (Gg)
(12,000 tons) per year.  This would increase the  amount of solid waste
generated at the smelter from 182 to 193 Gg (200,000 to 213,000  tons)
per year.  This would be about a 6 percent increase.  The  additional
solid waste can be handled by the smelter's existing solid waste disposal
system.  Since the alternative is based on use of  a  dry particulate
collection device, there would be no direct water  pollution impact.
     Energy impacts for Regulatory Alternative II  would be increased
electrical energy consumption.  To operate the control  system specified
by the alternative, annual electrical energy consumption would be
14.6 million kilowatt-hours per year (kWh/yr). Total  smelter energy
consumption is approximately 2,890 million kWh/yr.  Therefore, Regulatory
Alternative II would increase the total ASARCO-Tacoma electrical energy
consumption by 0.5 percent.
1.4  ECONOMIC IMPACT
     The economic impact of implementing Regulatory  Alternatives II and
III were evaluated.  Table 1-1 summarizes the assessment of these  impacts,
     The capital cost for installing the control  system specified  by
Regulatory Alternative II is $3.5 million.  This  represents a major
capital expenditure for ASARCO.  However, ASARCO  is  a major publicly
held corporation with a good credit rating and good  access to financing.
Even considering the possibility of additional capital  expenditures for
control equipment for the two ASARCO low arsenic throughput smelters,
it is determined that the ASARCO-Tacoma smelter would be able to obtain
the necessary capital to install the control system  at  the smelter.
The annualized cost to implement Regulatory Alternative II is estimated
to be $1.4 million.  If ASARCO chooses to absorb the costs by reducing
its profit margin, the profitability of the ASARCO-Tacoma  smelter  could
be reduced to 9.6 percent.  If ASARCO chooses to  maintain  its normal
profit margin and recover the costs by increasing  copper prices, the
price of the copper would increase 0.7 to 1.0 percent.
                                  1-4

-------
     Regulatory Alternative III  would reduce total  arsenic  emissions
from the ASARCO-Tacoma smelter by 282 Mg per year to  a  level  of  zero
emissions.  As described above,  this total  elimination  of  arsenic
emissions could be achieved only through the closure  of the ASARCO-Tacoma
smelter.  Closure of the smelter would eliminate the  jobs  of  approximately
800 ASARCO employees as well as  an additional 500 jobs  in  the local
community created by the economic activity  of the smelter.  This represents
approximately 1 percent of the civilian employment  in the  county where
the smelter is located.  In addition to providing jobs,  ASARCO annually
purchases about $20 million worth of goods  and services  from  local
companies.  ASARCO pays over $2  million per year in State  and local
taxes.  These revenues to local  companies and the State and local
governments would be eliminated  by the closure of the smelter.   Finally,
the ASARCO-Tacoma smelter is the only facility in the United  States
producing arsenic trioxide and metallic arsenic for commercial sale.
Closure of the smelter would require that all arsenic raw  materials for
the arsenic chemical manufacturing industry (e.g.,  pesticides and wood
preservative manufacturers) be imported to  the United States.
                               1-5

-------

-------
                    2.0  THE PRIMARY COPPER INDUSTRY

2.1  GENERAL
     Currently, there are 15 primary copper smelters operating or
temporarily closed in the United States.   Of these,  seven are located
in Arizona, two in New Mexico, and one each in Nevada,  Texas, Utah,
Tennessee, Michigan, and Washington.  The concentration of copper
smelters in the Southwest is due mainly to the local availability of
copper-bearing ores.  For the 15 copper smelters,  smelting capacity
totals approximately 1.72 million Mg (1.9 million  tons) of smelter
product (99 percent "blister" copper) per year.*  Table 2-1 lists
these 15 smelters, their locations, and estimated  capacities.
     Primary copper production in 1982 was 975,437 Mg (1,075,400 tons).2
This represented approximately a 60 percent utilization of domestic
primary copper smelting capacity.  Smelter capacity  in  the United
States appears to be relatively steady, with minimal prospects for
substantial additions before 1985.  The Bureau of  Mines forecasts the
total demand for copper in the year 2000  to be between  3.5 and
6.0 teragrams (Tg) (3.9 x 106 to 6.6 x 106 tons).  This forecast
represents an annual growth of 3.6 percent.  However, recycling of
scrap and the expansion of hydrometallurgical facilities are expected
to accommodate a substantial portion of this increased  demand.^
2.1.1  Raw Materials
     Copper ores are generally classified as sulfide, oxide, or native
depending on the predominant copper-bearing minerals they contain.
Although copper occurs in at least 160 minerals, only a few of these
have any commercial importance.  Table 2-2 lists the composition of
the more important sulfide and oxide minerals from which copper is
extracted.  Of the primary sulfide minerals, chalcopyrite is the most
abundant, followed by bornite and chalcocite.  Oxide minerals are
produced by the oxidation of primary sulfide minerals under certain
                                2-1

-------
              Table 2-1.  DOMESTIC PRIMARY COPPER SMELTERS
     Company

ASARCO, Incorporated
Tennessee Chemical
  Company

Inspiration Consolidated
  Copper Company

Kennecott Copper Corporation
Magma Copper Company

Phelps Dodge Corporation
Copper Range Company

       TOTAL
  Location
 Annual capacity3
Megagrams    (Tons)
El Paso, Texas
Hayden, Arizona
Tacoma, Washington

Copperhil1, Tennessee
Miami, Arizona
Garfield, Utah
Hayden, Arizona
Hurley, New Mexico
McGill, Nevada

San Manuel, Arizona

Ajo, Arizona
Douglas, Arizona
Hidalgo, New Mexico
Morenci, Arizona

White Pine, Michigan
  91,000
 182,000
  91,000

  13,600
 254,000
  71,000
  73,000
  45,000
(100,000)
(200,000)
(100,000)

 (15,000)
 136,000    (150,000)
(280,000)
 (78,000)
 (80,000)
 (50,000)
 181,000    (200,000)
64,000
115,000
163,000
191,000
52,000
(70,000)
(127,000)
(179,000)
(210,000)
(57,000)
                        1,722,600  (1,896,000)
Production of "blister" copper (99 percent Cu).
                                     2-2

-------
               Table 2-2.  MAJOR COPPER-BEARING MINERALS
     Type
   Mineral
Formula
 Sulfide
 Oxide
Chalcopyrite
Bornite
Chalcocite
Covellite
Malachite
Azurite
Chrysocolla
Cuprite
Cu3FeS3
Cu2S
CuS
CuC03 Cu(OH)2
2CuC03 Cu(OH)2
CuSi03 2H20
Cu20
climatic conditions.  When present, these are usually found in the
upper portions of copper ore deposits.  Native copper consists of
almost pure metallic copper.  Although found in small amounts in many
copper ore deposits, it is essentially unique to the upper peninsula
of Michigan.
     Copper ores consist of one or more of these copper-bearing minerals
disseminated within relatively large quantities of siliceous and other
earthy matter.  In addition, they also contain varying amounts of
other metals including sulfides and oxides of iron,  arsenic, antimony,
lead, zinc, etc.  In the United States, low grade sulfide ores account
for 85 to 95 percent of the total primary production.^  The average
tenor of these ores (copper content) is less than 1  percent.5  Virtually
all copper ores processed are beneficiated at the mine.   Sulfide ores
are crushed, finely ground, and concentrated by froth flotation.
Oxide ores are leached with acid, and the dissolved  copper is re-
covered by chemical precipitation on scrap iron.  Typically, copper
ore concentrates contain about 15 to 30 percent copper.
     In addition to copper, metals such as arsenic are also concentrated
in the concentration process.  The arsenic content of copper concentrates
processed at U.S. copper smelters is highly variable, ranging from a
few parts per million to several  percent.
                                  2-3

-------
     Table 2-3 presents the amount of arsenic input to the domestic
smelters, based on information received from the smelters  in  early
1983.6»7>8»9»10>1:L>12  The ASARCO-Tacoma smelter is a custom  smelter,
and is the only U.S. smelter which recovers arsenic trioxide  as  a
by-product.  Therefore, the smelter processes ore materials which
typically contain high concentrations of arsenic, obtained from  various
domestic and foreign sources.  As shown in the table, the  ASARCO-Tacoma
smelter introduces more arsenic in the feed material  to the smelter
than the combined total from all  other smelters.  The smelter also
handles substantial quantities of lead plant by-products and  flue dust
from other copper smelters.  As a result, more arsenic is  potentially
released from this smelter as process emissions and fugitive  emissions
than from the other smelters combined.
2.1.2  Process Description-^
     The pyrometallurgical process used for the extraction of copper
from sulfide ore concentrates is  based on iron's strong affinity for
oxygen as compared to copper's weak affinity for oxygen.  The purpose
of smelting is to separate the copper from the iron,  sulfur,  and
gangue materials.  Conventional practice includes three operations:
     1.   Roasting (optional) to  remove a portion of the concentrate
sulfur content.
     2.   Smelting of roasted calcines or unroasted ore concentrates
and fluxes in a furnace to form slag and copper-bearing matte.
     3.   Converting (oxidizing)  of the matte in a converter  to  form
blister copper (about 99 percent  pure copper).
     Figure 2-1 presents a pictorial representation of the copper
smelting process.  Figure 2-2 illustrates the three basic  operations
employed as well as materials entering or leaving each operation.
Briefly, the smelting of copper concentrates and precipitates is
accomplished by melting the charge and suitable fluxes in  a smelting
furnace.  Part or all of the concentrates may receive a partial  roast
to eliminate some of the sulfur and impurities such as arsenic.   In
the smelting furnace, the lighter impurities combine and float to the
top as slag to be skimmed off and discarded, while the copper, iron,
most of the sulfur, and any contained precious metals form a  product
known as matte which collects in  and is drawn off from the lower part
                                2-4

-------
               Table 2-3.   ARSENIC  INPUT  IN  THE  FEED
                      TO DOMESTIC COPPER  SMELTERS

Plant

ASARCO-Tacoma
ASARCO-Hayden
ASARCO-E1 Paso
Kennecott-Garf i el d
Kennecott-McGill
Phelps Dodge-Ajo
Inspi ration-Miami
Phelps Dodge-Hidalgo
Phelps Dodge-Douglas
Kennecott-Hayden
Phelps Dodge-Morenci
Magma-San Manuel
Tennessee Chemical
Company -Copperhil 1
Kennecott-Hurley
Copper Range-White Pine
Arsenic
Percent
4.0
0.6
0.5
0.14
0.4
0.3
0.033
0.018
0.03
0.015
0.006
0.006
0.0004
0.0005
0.008
content of
kg/hr
ggic
170
142d
118e
81 f
47
189
14
11
8.0
4.5n
2.0
1.3
1.0
o.yi
feeda.b
(Ib/hr)
(2185)
(375)
(314)
(261)
(179.3)
(103)
(41.1)
(30.6)
(24)
(17.7)
(9.99)
(4.39)
(2.9)
(2.14)
(1.53)
h
 The feed  is  a  mixture  of  concentrates,  precipitates,  lead  smelter
 by-products, and smelter  reverts.

 Does not  include recycled flue  dusts  and  other  intermediates,  except
 where noted.

"50 kg/hr  (111  Ib/hr) of this  amount  is  fed  directly to the arsenic
 plant.
d
 51 kg/hr  (112  Ib/hr) of this  amount  is  fed  directly to the converters.
^
"3.5 kg/hr (7.8 Ib/hr)  of  this amount  is fed directly  to the converters.

 6.5 kg/hr (14.2 Ib/hr) of this  amount is  fed directly to the converters,
g
 0.3 kg/hr (0.6 Ib/hr)  of  this amount  is fed directly  to the converters.

 0.2 kg/hr (0.35 Ib/hr) of this  amount is  fed directly to the converters,

 0.1 kg/hr (0.22 Ib/hr) of this  amount is  fed directly to the converters,
                                 2-5

-------
     EHTEBDiS THE SYSTEM
LEAVING THE SYSTEM
     Raw cnncsntratas
     Fuel
     Air
Flux and
fettling material
Fuel
Air
Siliceous  flux
Xiscsllaneous
                                       ROASTER
                                        «3
                                        CO
                                SMELTING FURNACE
material  high in copper
Air
                                    CONVERTER
Gases,  volatiIs oxides,
and dust  to dust recovery
and stack
    Gases and dust
    to waste heat boilers,
    dust recovery, and  stack
    Slag to dump
                                                          Gases  to stack
                                                          Blister copper
                                                          to  relinery
              Figure 2-2.   Primary Copper Smelting Process
                                       2-7

-------
 of the  furnace.  The molten matte is transferred to a converter where
 air blown through the matte burns off the sulfur, oxidizes the iron
 for removal in a slag, and yields a 99 percent blister copper product.
 Typically, the blister copper is further refined in an anode furnace
 prior to the casting of copper anodes for electrolytic refining.  A
 more detailed discussion of roasting, smelting, and converting operations
 is presented in the following subsections.
     2.1.2.1  Roasting.  In roasting of copper sulfide ore concentrates,
 concentrates are heated to a high temperature (but below the melting
 point of the constituents) in an oxidizing atmosphere to eliminate a
 portion of the sulfur contained as sulfur dioxide (S02); to remove
 volatile impurities such as arsenic, antimony, and bismuth; and to
 preferentially convert a portion of the iron sulfides present to iron
 oxides.  The roasted concentrate is called calcine.  The degree of
 roast (i.e., the amount of sulfur and iron oxidized in the roasting
 operation) is dependent on the desired quality of the charge to the
 smelting furnace.  Representative reactions include the following:
               2CuFeS2
4FeS
                    02
                   702
                           2FeS
                    FeS + S
                    S02
4S02
     Currently, 7 of the 15 existing primary copper smelters  roast
concentrates prior to smelting.  Two types of roasters  are used:
multiple-hearth roasters and fluid-bed roasters (refer  to Figure  2-3).
With both types, the roasting process is generally autogenous.  The
roaster operating temperature is typically about 650°C  (1,200°F).
     In multiple-hearth type roasters, the hearths are  constructed  of
refractory brick with a slight arch.  The external portion of the
furnace is a brick-lined, steel shell with hinged doors  and inspection
plates at each level.  The moist concentrate enters  the  roaster through
an annular opening to the top-most or dryer hearth.   Rabble arms,
attached to the hollow central shaft, rotate as the  shaft turns and
plow through the charge to continuously expose fresh surfaces  to the
oxidizing air.  The rabble blades are set at an angle and,  in  addition
                                  2-8

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to stirring the material, move it alternately from the center of the
hearth to the periphery where it falls to the next Jower hearth.
Finished calcine is discharged through holes on the circumference of
the bottom hearth.
The air required for roasting is admitted through the central
shaft and, by means of valves, the air supply to each hearth may be
regulated. Roaster gases are drawn off through gas outlets located
just below the dryer hearth. The discharge from the dryer hearth to
the top roasting hearth prevents the escape of gas from the interior
of the roaster.
Fluid-bed roasters are cylindrical, refractory-lined vessels
equipped with diffusion plates in the bottom containing tuyeres or
bubble caps through which air is blown from the bottom. Finely ground
material (60 percent minus 200 mesh) is introduced either as a slurry
through a feed pipe or relatively dry (6 to 12 percent moisture)
through a screw conveyor. The feed is continuously delivered into the
combustion chamber. Roasting occurs as the sulfide particles fall
through the oxidizing air.
Combustion air from the windbox passes through distribution
plates at the bottom of the chamber into the combustion zone. Because
of the large surface area of the finely ground material exposed to the
airstream, the residence time in the oxidizing atmosphere is short.
The reaction is self-sustaining. Oil, gas, .or pulverized coal burners
are required only to preheat the roaster to combustion temperature.
Roaster gases are drawn off through flues at the top of the
chamber and immediately pass to cyclone collectors, followed by cooling
and final dust collection. As much as 85 percent of the feed is
carried with the gas stream and, hence, cyclones are an integral part
of the roasting operation. Screw conveyors collect this finished
calcine as well as that from the bottom of the combustion chamber for
discharge into hoppers.
For either type of roaster, there are three major operating
variables: feed rate, combustion air flow rate, and temperature. A
key difference between the two is the S02 concentration in the roaster
offgases. Sulfur dioxide concentrations in the roaster offgases are
considerably higher for fluid-bed roasters than for multi-hearth
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roasters due to the lower total air volume. Average stack gas S02
concentration is about 12 percent with a maximum of 18 percent for
fluid-bed roasters and only 3 to 6 percent for multi-hearth roasters.14
2.1.2.2 Smelting. Smelting is the pyrometallurgical process in
which solid material is melted and subjected to certain chemical
changes. During copper smelting, hot calcines from the roaster or
raw, unroasted concentrates are melted in a smelting furnace with
siliceous or limestone flux. Converter slag, collected dust, oxide
ores, and any other material rich in copper may be added to the furnace
charge. Copper and iron which are present in the charge combine with
sulfur to form a stable cuprous sulfide. Excess sulfur unites with
iron to form a stable ferrous sulfide (FeS). The combination of the
two sulfides, known as matte, collects in the lower area of the furnace
and is removed. Such mattes may contain from 15 to 50 percent copper,
with a 40 to 45 percent copper content being most common. Mattes may
also contain impurities such as sulfur, antimony, arsenic, iron, and
precious metals.
The remainder of the molten mass containing most of the other
impurities is known as slag. Slag is of lower specific gravity,
floats on top of the matte, and is drawn off and discarded. Slags in
copper smelting are ideally represented by the composition 2FeO«Si02,
but contain alumina from the various charge materials and calcium
oxide which is added for fluidity. Since slags are discarded, the
copper contained in the slag is a major source of copper loss in
pyrometallurgical practice. Copper concentration in the slag increases
with increasing matte grade, which limits the matte grades normally
obtained in conventional practice to below 50 percent copper.
Currently, conventional reverberatory furnaces are used at 11 of
the 15 existing primary copper smelters. Two smelters employ electric
furnaces, while one smelter employs the Outokumpu flash furnace and
another a Noranda continuous smelter. Two smelters will be modifying
one or more of their reverberatory furnaces to convert them to oxygen-
sprinkle smelting, while two more are planning to retire their rever-
beratory furnaces within the next few years and install Inco flash
smelting furnaces. In a reverberatory furnace (Figure 2-4), fossil
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fuels such as oil or natural gas are burned above the copper concentrates
being smelted. The furnace is a long, rectangular structure, generally
about 11 m (36 ft) in width and 40 m (131 ft) in length, with an arched
roof and burners at one end. Flames from the burners may extend half
the length of the furnace. Temperatures at the firing end of the
furnace exceed 1,500°C (2,730°F). Part of the heat in the combustion
gas radiates directly to the charge lying on the hearth below, while a
substantial part radiates to the furnace roofs and walls, and is reflected
down to the charge. The roofs of the older reverberatory furnaces are
sprung-arch silica roofs, while almost all newer furnaces have suspended
roofs of basic refractory.
Over the years, two types of reverberatory furnaces have evolved,
each with its own specific charging methods. The older type is the
deep bath reverberatory furnace which contains a large quantity of
molten slag and matte at all times. In modern, deep bath reverberatory
furnaces, the molten material is held in a refractory crucible with
cooling water jackets along the sides, which greatly diminishes the
danger of a breakout of the liquid material. In deep bath smelting,
several methods exist for charging. Wet concentrates can be charged
using slinger belts (high-speed conveyors) that spread the concentrates
on the surface of the molten bath. Dry concentrates or calcines from
the roaster can be charged through the roof or via a Wagstaff gun (an
inclined tube). Roof charging (side charging) is rarely practiced in
conjunction with deep bath smelting because of dusting problems with
fine dry calcine and explosion potential with green charge. Wagstaff
guns minimize these problems and are commonly used.
Side or roof charging is usually used with green charge. With
the charge dropped through a series of feed holes in the arch near the
walls, a buildup of material forming banks results. The banks slowly
melt and serve as protection to the side walls, eliminating the requirement
for special cooling.
Combustion gases contain from 15 to 45 percent of the sulfur in
the original charge depending primarily upon whether or not the
concentrate was roasted. However, because of the high volume of
combustion air, S02 concentrations are low, with averages varying from
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fluid-bed roasters, converters, and other types of smelting furnaces,
cannot be economically utilized as feed for sulfuric acid plants.
Electric smelting furnaces provide the heat necessary for smelting
copper ore concentrates by allowing carbon electrodes to come into
contact with the molten bath within the furnace. The electrodes dip
into the slag layer of the bath, forming an electrical circuit. When
an electric current is passed through this circuit, the slag resists
its passage, generating heat and producing smelting temperatures.
Charge concentrates and fluxing materials are fed through the roof,
and a layer of unsmelted charge covers the molten bath. Heat is trans-
ferred from the hot slag to the charge floating on its surface, and as
the copper concentrates and fluxes are smelted, they settle into the
bath forming slag and matte. The chemical and physical changes occurring
in the molten bath are similar to those occurring in the molten bath of
a reverberatory furnace.
In flash smelting, copper sulfide ore concentrates are smelted by
burning a portion of the iron and sulfur contained in the concentrates
while they are suspended in an oxidizing environment. As such, the
process is quite similar to the combustion of pulverized coal. The
concentrates and fluxes are injected with preheated air, oxygen-enriched
air, or even pure oxygen, into a furnace of special design. Then,
smelting temperatures are attained as a result of the heat released by
the rapid, flash combustion of iron and sulfur. Flash smelting technology
has been developed by two companies: International Nickel Company
(Inco) in Canada and Outokumpu Oy in Finland. The major difference
between the two technologies is in the design of the smelting furnace
and the oxidizing environment within the furnace. The Inco furnace
uses pure oxygen, while the Outokumpu furnace employs preheated air or
oxygen-enriched air as the oxidizing medium.
Two smelters are currently planning to convert one or more of
their reverberatory furnaces to oxygen-sprinkle smelting. In essence,
this conversion will allow the existing reverberatory furnaces to behave
like flash furnaces. Specially designed burners positioned on the
furnace roof are used to introduce and disperse a mixture of primarily
dried concentrates and oxygen. The heat required for smelting is
generated from the flash combustion of the sulfur in the mixture.
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The result is an increase in furnace efficiency and the production of a
strong SOg process gas stream suitable.for treatment in. a sulfuric acid
plant.
2.1.2.3 Converting. Matte produced in the reverberatory furnace
is transferred in ladles to the converters using overhead cranes.
Fourteen of the 15 smelters use converters of the cylindrical Fierce-Smith
type, the most common size being 4 by 9 m (13 by 30 ft). Figure 2-5
is a sketch of a Fierce-Smith copper converter. An alternative to the
Fierce-Smith converter is the newer Hoboken or "siphon" converter.
The Hoboken converter, currently used by one of the domestic smelters,
is essentially the same as the Fierce-Smith converter except that it
is fitted with a side flue located at one end of the converter and
shaped as an inverted "U." This flue arrangement permits siphoning of
the converter gases from the interior of the converter, using variable-speed
fans and dampers, directly to the offgas collection system. By maintaining
a slightly negative pressure at the converter mouth, it is possible to
minimize or eliminate emissions. Problems in improper draft at the
converter mouth have been reported by Inspiration Consolidated Copper
Company, the only domestic user of Hoboken converters. One of the
five Hoboken converters operated by Inspiration has been modified to
eliminate the siphon area. The modification has resulted in improved
performance, and Inspiration intends to modify its four remaining
smelters in similar fashion.16
In both Fierce-Smith and Hoboken converters, air is blown from
the side through a series of openings called tuyeres. During the
initial blowing period (the slag blow), FeS in the matte is preferentially
oxidized to FeO and FesO,/)., and sulfur is removed with the offgases as
S02- Flux is added to the converter to combine with iron oxide and
forms a fluid iron silicate slag. When all the iron is oxidized, the
slag is skimmed and poured off from the furnace at various times during
slag formation, leaving behind "white metal" or molten Cu2S.
During this stage, fresh matte is charged into the converter, and
the slag blowing continues until a sufficient quantity of white metal
has accumulated. When this happens, the white metal is oxidized with
air to blister copper during the "copper blow." The blister copper is
removed from the converter and cast or subjected to additional fire
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refining prior to casting. Converter blowing rates can vary between
340 and 855 normal m3/min (12,000 to 30,000 scfm) of air.
In general practice, the matte is added to the converter in two
to six steps, each step followed by oxidation of much of the FeS from
the charge. The resulting slag is poured from the converter after
each oxidation step, and a new matte addition is made. In this way,
the amount of copper (as matte) in the converter gradually increases
until there is a sufficient amount for a final copper-making "blow."
At this point, the FeS in the matte is blown down to about 1 percent,
a final slag is removed, and the resulting white metal is oxidized to
blister copper. The converting process is terminated when copper oxide
begins to appear with the liquid copper. The offgas flow rate leaving
the primary head of converters typically ranges from 850 to 1,260
Nm3/min (30,000 to 45,000 scfm). The average S02 concentration in
these gases is normally in the range of 4 to 5 percent during the
slag blow and 7 to 8 percent during the copper blow. Values of the
overall average S02 concentration in the offgases (after gas cleaning)
from existing domestic converting operations fall in the range of
1.6 to 6.5 percent on a dry basis. The industry-wide average value,
as weighted by the respective plant flow rates, is 4.6 percent.17
2.1.2.4 Refining. Virtually all copper produced by matte smelting
i,s subsequently electrorefined. For this reason, the final liquid
copper product of the smelter must be suitable for the casting of
strong, thin anodes. In a majority of cases, anode copper is fire
refined directly from molten blister copper.
Fire refining is performed in rotary-type refining furnaces
resembling Fierce-Smith converters, or in small hearth furnaces. The
rotary-type predominates when molten blister copper is treated directly,
while hearth furnaces are used when melting of solid charges is practiced,
The temperature of operation is about 1,130 to 1,150°C, which provides
sufficient superheat for the subsequent casting of anodes. There is
very little heat produced by refining reactions, and some combustion
of fuel is necessary to maintain the temperature in the furnace.
Dimensions of the rotary-type refining furnaces vary; however, a
4 by 9 m (13 by 30 ft) furnace may be regarded as typical. Gas
flow rates are generally low so as to accurately control the metal
2-17
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composition. Gas pressures at the tuyeres are near 250 to 600 kPa
(2.5 to 6 atm). Refining a 250-ton charge of copper requires 3
to 5 hours: 1/2 to I hour for the oxidation step, and the remainder
for the deoxidation ("poling") step.
A typical sequence of events in rotary anode furnace refining is:
1. Molten blister copper is added to the anode furnace as it
becomes available from the converters until about 150 to 300 Mg
(165 to 331 tons) have been accumulated;
2. The accumulated charge is then oxidized by blowing air through
the tuyeres until the sulfur content is lowered to 0.001 to 0.003 percent S,
at which time a small ingot sample of copper shows a slight contraction
or small hole; and at which time the oxygen level in the copper is
about 0.6 percent; '
3. The oxygen is then removed from the copper by blowing natural
gas, reformed natural gas, or propane through the tuyeres. The oxygen
level in the anode copper is 0.005 to 0.2 percent after this operation,
which gives a "flat set" to the anodes when they are cast. The correct
"end point" is determined by casting a sample of the copper (which
should set to a flat surface) or by continuously analyzing for oxygen
with an oxygen probe;
4. Finally, the liquid metal may be covered with low sulfur coke
to prevent reoxidation of the copper.
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Several older modifications of this process are still being used
in which the air is introduced via steel lances, and in which the
oxygen-removal step is performed by lowering large logs or poles of
green wood into the copper (thereby providing the necessary hydrocarbons).
Both of these steps are clumsy, and are being discontinued.
Similarly, the use of the hearth type of anode furnace has by and
large been discontinued except where scrap (including anode scrap)
and/or blister copper are melted. A typical anode hearth furnace
resembles a small reverberatory furnace o width 5 m (16 ft), length
15 m (49 ft), height 3 m (10 ft), inside dimensions o capable of holding
300 Mg (331 tons) of copper. In hearth furnaces, the air and hydrocarbons
are introduced into the copper by submerging steel lances into the
molten bath. Wooden poles are often used for the oxygen removal step.
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2.1.3 Description of the ASARCO-Tacoma Smelter
The ASARCO smelter at Tac'oma, Washington, is a custom smelter
which processes copper ore concentrates, precipitates, and smelter
by-products from numerous domestic and foreign sources. The smelter
produces about 320 Mg (353 tons) of anode copper per day at full smelt
and houses the only arsenic production facility in the United States.
Copper smelter facilities include 10 roasters, (6 Herreschoff multi-hearth
roasters and 4 C & W multi-hearth roasters), 2 reverberatory smelting
furnaces, 3 Pierce-Smith converters (a fourth Fierce-Smith converter
is used as a holding furnace only), and 2 tilting anode furnaces.
Arsenic production facilities consist of three Godfrey roasters, three
arsenic trioxide settling chambers or kitchens, storage facilities,
and a metallic arsenic plant.
The roaster charge, which consists of a blend of concentrates,
precipitates, lead speiss, flue dust, and fluxing materials, typically
contains 3 to 4 percent arsenic and 7 to 10 percent moisture. At full
smelt, six or seven roasters are used. Charging is continuous. The
calcine produced, about 45 Mg (50 tons) per hour, is intermittently
discharged from hoppers located below the roasters into larry cars for
transport to one of two reverberatory furnaces. Typically, two 5.9-Mg
(6.5-ton) cars are charged every 15 minutes.
The smelter has two reverberatory smelting furnaces, each with an
approximate smelting capacity of 1,090 Mg (1,200 tons) per day. The
designated Number 2 furnace is used almost exclusively. The furnace
measures 33.5 m (110 ft) in length and 9.8 m (32 ft) in width and is
fired by either oil or natural gas. Furnace charging is accomplished
by discharging the larry cars through one of four Wagstaff guns located
along the furnace sidewalls. Typically, it takes less than 1 minute
to discharge one car. At full smelt, two cars are discharged about
every 15 minutes. To minimize potential fugitive emissions during
charging, a manual control override is used which simultaneously opens
the furnace flue control damper and reduces the fuel supply to the
furnace fire prior to each charge to prevent pressure surges in the
furnace.
Matte is tapped from the furnace as required by converter operations
through one of four tapping ports. Only one tapping port is used at
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a time. The matte flows through a cast copper launder to a 4.25 m3
(150 ft3) cast steel ladle for transfer to the converters. At full
smelt, about 45 ladles are transferred per day. It takes about 7 minutes
to fill one ladle. Similarly, slag is skimmed through one of two
tapping ports as required to maintain the proper slag level in the
furnace and transferred to a 5-pot slag train for transit to the slag
dump. Once tapped, the slag flows through a cast steel launder and
into a 2.8 m3 (100 ft3) cast steel slag pot. At full smelt, about
20 5-pot slag trains are dumped per day. Each train takes about
15 minutes to fill.
Matte from the reverberatory furnace is transferred by crane to
one of the Pierce-Smith converters. The converters measure 4.0 m
(13 ft) in diameter by 9.1 m (30 ft) in length. In addition to copper
matte, smelter reverts and cold dope materials are also processed.
Typically, only two converters are on blow at any one time. A converter
cycle normally takes from 10 to 12 hours. With dilution air, the
offgas flow per blowing converter is about 1,130 normal m3/min (40,000 scfm)
and contains from 3 to 4 percent S02- Blister copper produced is
transferred to the anode furnaces for refining and casting. The slag
skimmed from the molten charge is recycled to the reverberatory furnace.
Arsenic-laden dust recovered from the particulate control systems
servicing the multi-hearth roasters, the reverberatory furnace, and the
converters is transferred to the arsenic recovery plant. The dust is
charged to one of the Godfrey roasters where the arsenic trioxide
contained in the dust is volatilized. The roaster calcine or troughs,
now low in arsenic content, are discharged to open freight cars and
subsequently recycled through the copper smelter complex to resorb the
copper value. The volatilized arsenic is passed through a series of
arsenic settling chambers, called kitchens, where the temperature of
the gas and vapor are controlled and the arsenic trioxide is condensed.
The kitchens are rectangular structures containing multiple baffled
chambers. There are 3 arsenic kitchens, 1 with 10 chambers and 2 with
15 chambers. The arsenic-laden gas enters the first chamber at approximately
205°C (400°F) and exits the final chamber at 100°C (212°F) or less.
The exhaust gases from the kitchens are treated in a baghouse prior to
being discharged to the atmosphere. The condensed arsenic trioxide
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(90 to 95 percent pure) is removed periodically from the settling
kitchens and placed in storage. This material is shipped as a product.
ASARCO-Tacoma also operates an elemental arsenic plant, independent
of the copper circuit, in which purchased, refined arsenic trioxide is
reduced to metallic arsenic. Offgases from the two metallic arsenic
furnaces pass through condensers (one per furnace) in which the gaseous
arsenic is collected as a solid and periodically removed. The metallic
arsenic is loaded into barrels for shipment. Offgases from the arsenic
condensers are treated in the arsenic trioxide plant baghouse.
2.2 ARSENIC DISTRIBUTION AND EMISSIONS AT ASARCO-TACOMA
Arsenic elimination during copper smelting occurs primarily by
volatilization and slagging. The bulk of the arsenic is volatilized
in most pyrometallurgical processes and removed with the offgases. In
the presence of oxygen, elemental arsenic or arsenic sulfides oxidize
to arsenic trioxide, which is extremely volatile. However, in an
oxidizing atmosphere, the arsenic trioxide (AS203) may oxidize to the
higher oxide (As20s) which is less volatile and forms stable nonvolatile
arsenates with other metallic oxides.
The elimination of arsenic in the smelting furnace by slagging is
dependent upon the concentration or partial pressure of the arsenic
trioxide.^ if the partial pressure of the oxide is sufficient to
allow it to penetrate the slag layer and thus escape, volatili-zation
will occur. However, if the partial pressure is not great enough to
allow passage through the slag layer, the arsenic will be retained in
the slag and thus be eliminated on slag disposal. The magnitude of the
partial pressure is dependent upon the amount of arsenic present in the
process stream.
Arsenic emissions from primary copper smelters can be categorized
as process and fugitive emissions. Process emission sources include
primary offgas emissions from roasting, smelting, and converting
operations. Fugitive emissions include those emissions which escape
from process flow streams due to leakage through process exhaust
systems, material transfer systems, or ineffective capture at the
source of generation.
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2.2.1 Arsenic Distribution and Process Emissions at ASARCO-Tacoma
The arsenic distribution for this smelter is shown in Figure 2-6.
The arsenic input of 991 kg/hr (2,185 Ib/hr) includes the arsenic
found in the concentrates, precipitates, and lead smelter by-products
and reverts, as well as the input to the metallic arsenic plant.
Figure 2-6 is based on a detailed arsenic material balance supplied by
ASARC0.9 Process emissions are calculated based on the control systems
currently in place at ASARCO-Tacoma. Fugitive emission-s are not included
in the material balance. Arsenic flow rates are based on the total
tonnages transferred in a year (1982) divided by 8,544 hours of operation,
These rates, therefore, do not reflect instantaneous flow at full
capacity. It should also be noted that operations curtailment at the
ASARCO-Tacoma smelter in 1982 was approximately 25 to 30 percent.19
The arsenic collection efficiency of the particulate control
equipment is significantly affected by the temperature at which arsenic
trioxide enters and leaves the equipment. For this reason, all assigned
control efficiencies are dependent on the temperature at which the
efficiencies were determined. In the arsenic material balance shown in
Figure 2-6, estimated arsenic collection efficiencies for control
devices were based on information presented in Section 3.2.1. Based on
the results of emission source testing at the smelter, the roaster
baghouse was assigned an efficiency of 99.8 percent 'and electrostatic
precipitator No. 1 was assigned an efficiency of 98 percent. Electro-
static precipitator No. 2 and the electrostatic precipitators upstream
of the acid and sulfur dioxide plants were assumed to be 96 percent
efficient based on engineering judgment. The chemical plants themselves
were assigned an arsenic removal efficiency of 99 percent. An efficiency
rating of 98 percent was assumed for the new arsenic plant baghouse.
Table 2-4 presents a summary of process arsenic emissions estimated
for ASARCO-Tacoma. These estimates are based on inputs to the various
process steps and collection efficiencies of associated control equipment.
In the absence of any controls, the major sources of arsenic
process emissions at ASARCO-Tacoma in order of magnitude of emissions
are the reverberatory furnaces, the arsenic plant, the multi-hearth
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