United States
Environmental Protection
Agency
Office of Air Quality 453/R-93-030t
Planning and Standards ju|y 1993
Research Triangle Park. NC 27711
AJQL
& EPA
Chromium Emissions from Chromium
Electroplating and Chromic Acid
Anodizing Operations-Background
Information for Proposed Standards
Volume I
NESHAP
••4
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Chromium Emissions from Chromium Electroplating
and Chromic Acid Anodizing Operations-
Background Information for Proposed Standards
Volume I
U. S. Environmental Protection Agency
Office of Air and Radiation
Office of Air Quality Planning and Standards
Research Triangle Park, NC 27711
Prepared by:
Midwest Research Institute
Suite 350
401 Harrison Oaks Boulevard
Gary, North Carolina 27513
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MASTER TABLE OF CONTENTS
VOLUME I
Page
LIST OF FIGURES viii
LIST OF TABLES -. xi
LIST OF ABBREVIATIONS xxii
GLOSSARY OF ELECTROPLATING TERMS xxv
CHAPTER 1. SUMMARY 1-1
CHAPTER 2. INTRODUCTION 2-1
CHAPTER 3. CHROMIUM ELECTROPLATING AND CHROMIC ACID
ANODIZING OPERATIONS 3-1
CHAPTER 4. EMISSION CAPTURE AND CONTROL TECHNIQUES ... 4-1
CHAPTER 5. MODEL PLANTS AND CONTROL OPTIONS 5-1
CHAPTER 6. ENVIRONMENTAL IMPACTS 6-1
CHAPTER 7. COST ANALYSIS OF CONTROL OPTIONS 7-1
CHAPTER 8. ECONOMIC IMPACTS 8-1
VOLUME II
LIST OF FIGURES v
LIST OF TABLES viii
LIST OF ABBREVIATIONS XX
GLOSSARY OF ELECTROPLATING TERMS xxiii
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
APPENDIX D. EMISSION MEASUREMENT AND CONTINUOUS
MONITORING D-l
APPENDIX E. MODEL PLANT PRODUCTION RATE CALCULATIONS . E-l
APPENDIX F. DEVELOPMENT OF MODEL PLANT COSTS F-l
APPENDIX G. ANALYSIS OF ANNUAL PLATING LINE COSTS
FOR THE TRIVALENT CHROMIUM PLATING
PROCESS VERSUS THE HEXAVALENT CHROMIUM
PLATING PROCESS G-l
APPENDIX H. NATIONWIDE IMPACT ANALYSES H-l
11
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TABLE OF CONTENTS
VOLUME I
Page
LIST OF FIGURES viii
LIST OF TABLES , xi
LIST OF ABBREVIATIONS xxii
GLOSSARY OF ELECTROPLATING TERMS xxv
CHAPTER 1. SUMMARY 1-1
1.1 CONTROL OPTIONS 1-1
1.2 ENVIRONMENTAL IMPACT 1-2
1.2.1 Hard Chromium Electroplating
Operations 1-2
1.2.2 Decorative Chromium
Electroplating Operations ... 1-2
1.2.3 Chromic Acid Anodizing
Operations 1-3
1.3 ECONOMIC IMPACT 1-3
CHAPTER 2. INTRODUCTION 2-1
2.1 BACKGROUND AND AUTHORITY FOR
STANDARDS 2-1
2.2 SELECTION OF POLLUTANTS AND SOURCE
CATEGORIES 2-5
2.3 PROCEDURE FOR DEVELOPMENT OF NESHAP . . 2-6
2.4 CONSIDERATION OF COSTS 2-9
2.5 CONSIDERATION OF ENVIRONMENTAL
IMPACTS 2-10
2.6 RESIDUAL RISK STANDARDS 2-11
CHAPTER 3. CHROMIUM ELECTROPLATING AND CHROMIC
ACID ANODIZING OPERATIONS 3-1
3.1 GENERAL 3-1
3.2 PROCESS DESCRIPTION 3-2
3.2.1 Electrochemistry 3-2
3.2.2 Hard Chromium
Electroplating of Metals ... 3-4
3.2.3 Decorative Chromium
Electroplating of Metals ... 3-11
3.2.4 Decorative Chromium
Electroplating of Plastics 3-17
3.2.5 Chromic Acid Anodizing of
Aluminum 3-18
3.2.6 Other Plating and Metal
Treatment Processes Involving
Chromium 3-23
3.3 UNCONTROLLED EMISSIONS 3-27
3.3.1 Hard and Decorative
Chromium Plating Operations . . 3-28
3.3.2 Chromic Acid Anodizing
Operations 3-37
111
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TABLE OF CONTENTS
VOLUME I (continued)
Page
3.4 EXISTING STATE REGULATIONS 3-41
3.4.1 California 3-42
3.4.2 Connecticut 3-43
3.4.3 Kentucky 3-43
3.4.4 Maine 3-44
3.4.5 Maryland 3-44
3.4.6 Nevada 3-44
3.4.7 New Hampshire 3-45
3.4.8 North Carolina 3-45
3.4.9 Rhode Island 3-45
3.4.10 South Carolina 3-45
3.4.11 Utah 3-45
3.4.12 Vermont 3-45
3.4.13 Virginia 3-46
3.4.14 Wisconsin 3-46
3.5 REFERENCES FOR CHAPTER 3 3-47
CHAPTER 4. EMISSION CAPTURE AND CONTROL TECHNIQUES ... 4-1
4.1 EMISSION CAPTURE TECHNIQUES 4-1
4.1.1 Local Ventilation 4-1
4.1.2 Lateral Exhaust Systems 4-2
4.1.3 Factors Affecting Performance
of Local Exhaust Ventilation . 4-6
4.2 EMISSION CONTROL TECHNIQUES 4-7
4.2.1 Mist Eliminators 4-8
4.2.2 Scrubbers 4-16
4.2.3 Chemical Fume Suppressants ... 4-26
4.2.4 Plastic Balls 4-31
4.2.5 Moisture Extractors 4-31
4.3 PERFORMANCE CAPABILITIES OF
CONTROL TECHNIQUES FOR CHROMIUM
EMISSIONS 4-31
4.3.1 Tests at Hard Chromium
Electroplating Operations ... 4-35
4.3.2 Tests at Decorative Chromium
Electroplating Operations ... 4-65
4.3.3 Summary and Discussion of
Emission Test Results 4-68
4.4 REFERENCES FOR CHAPTER 4 4-76
CHAPTER 5. MODEL PLANTS AND CONTROL OPTIONS 5-1
5.1 MODEL PLANTS 5-1
5.1.1 Model Plant Sizes 5-2
5.1.2 Model Plant Production and
Process Parameters 5-3
5.1.3 Capture System, Control Device,
and Stack Parameters 5-6
IV
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TABLE OF CONTENTS
VOLUME I (continued)
Page
5.2 BASELINE CONDITIONS 5-7
5.2.1 Baseline Levels of Control ... 5-8
5.2.2 Number of Operations Nationwide . 5-10
5.3 CONTROL OPTIONS 5-11
5.3.1 General 5-11
5.3.2 Hard Chromium Plating 5-11
5.3.3 Decorative Chromium Plating ... 5-12
5.3.4 Chromic Acid Anodizing 5-12
5.3.5 Impact Assessment 5-13
5.4 REFERENCES FOR CHAPTER 5 5-37
CHAPTER 6. ENVIRONMENTAL IMPACTS 6-1
6.1 INTRODUCTION 6-1
6.2 AIR POLLUTION IMPACTS 6-1
6.2.1 Hard Chromium Electroplating . . 6-2
6.2.2 Decorative Chromium
Electroplating 6-3
6.2.3 Chromic Acid Anodizing 6-5
6.3 ENERGY IMPACTS 6-6
6.3.1 Hard Chromium Electroplating . . 6-8
6.3.2 Decorative Chromium
Electroplating 6-11
6.3.3 Chromic Acid Anodizing 6-13
6.4 WATER POLLUTION IMPACTS 6-15
6.5 SOLID WASTE IMPACTS 6-16
6.6 OTHER ENVIRONMENTAL IMPACTS 6-17
6.7 OTHER ENVIRONMENTAL CONCERNS 6-17
6.7.1 Irreversible and Irretrievable
Commitment of Resources .... 6-17
6.7.2 Environmental Impact of Delayed
Regulatory Action 6-17
6.8 REFERENCES FOR CHAPTER 6 6-38
CHAPTER 7. COST ANALYSIS OF CONTROL OPTIONS 7-1
7.1 INTRODUCTION 7-1
7.2 BASES FOR COSTS OF EMISSION CONTROL
TECHNIQUES 7-1
7.2.1 New Operations 7-1
7.2.2 Existing Operations 7-21
7.3 MODEL PLANT COSTS FOR HARD CHROMIUM
PLATING OPERATIONS 7-23
7.3.1 Chevron-Blade Mist Eliminators
and Single Packed-Bed
Scrubbers 7-23
7.3.2 Mesh-Pad Mist Eliminators .... 7-25
7.4 MODEL PLANT COSTS FOR DECORATIVE
CHROMIUM PLATING OPERATIONS 7-26
7.4.1 Single Packed-Bed Scrubbers ... 7-26
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TABLE OF CONTENTS
VOLUME I (continued)
Page
7.4.2 Mesh-Pad Mist Eliminators .... 7-27
7.4.3 Chemical Fume Suppressants . . . 7-28
7.4.4 Trivalent Chromium Process ... 7-28
7.5 MODEL PLANT COSTS FOR CHROMIC ACID
ANODIZING OPERATIONS 7-30
7.5.1 Chevron-Blade Mist Eliminators
and Single Packed-Bed
Scrubbers 7-31
7.5.2 Mesh-Pad Mist Eliminators .... 7-32
7.5.3 Chemical Fume Suppressants . . . 7-33
7.6 TOTAL INDUSTRY COSTS 7-33
7.6.1 Hard Chromium Electroplating . . 7-34
7.6.2 Decorative Chromium
Electroplating 7-36
7.6.3 Chromic Acid Anodizing 7-37
7.7 OTHER COST CONSIDERATIONS 7-37
7.7.1 Water Pollution Control Act ... 7-37
7.7.2 Resource Conservation and
Recovery Act 7-38
7.7.3 Occupational Safety and Health
Administration Act 7-41
7.8 REFERENCES FOR CHAPTER 7 7-99
CHAPTER 8. ECONOMIC IMPACTS
8.1 INDUSTRY ECONOMIC PROFILE 8-1
8.1.1 Background 8-1
8.1.2 Chromite Ore Supply and Demand . 8-2
8.1.3 Chromic Acid Supply and Demand . 8-7
8.1.4 Suppliers of Electroplating and
Anodizing Chemicals 8-8
8.1.5 Chromium Electroplating and
Anodizing Firms and Plants . . 8-8
8.1.6 Size and Geographical Distribution
of Chromium Electroplaters and
Anodizers 8-11
8.1.7 Substitutes 8-12
8.1.8 Imports and Exports 8-16
8,1.9 Profile of Selected Product
Markets in Chromium
Electroplating 8-17
8.1.10 Chromic Acid Anodizing 8-25
8.2 ECONOMIC IMPACT ANALYSIS 8-27
8.2.1 Introduction 8-27
8.2.2 Overview 8-28
VI
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TABLE OF CONTENTS
VOLUME I (continued)
Page
8.2.3 General Methodology of the
Analysis 8-31
8.2.4 Economic Analysis of the
Selected Products 8-37
8.2.5 Quantity and Revenue Effects . . 8-67
8.2.6 Total Industry Impacts 8-70
8.2.7 Small Business Impacts 8-71
8.3 REFERENCES FOR CHAPTER 8 8-86
VI1
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LIST OF FIGURES
Figure 3-1.
Figure 3-2.
Figure 3-3.
Figure 3-4.
Figure 3-5.
Figure 4-1.
Figure 4-2.
Figure 4-3.
Figure 4-4.
Figure 4-5.
Figure 4 - 6.
Figure 4-7.
Figure 4-8.
Figure 4-9.
Figure 4-10.
Figure 4-11.
Figure 4-12.
Schematic of a typical electrolytic cell
Basic components of chromium electroplating
equipment
Flow diagram for a typical hard chromium
plating process
Flow diagram for decorative chromium
plating on a metal substrate . . .
Flow diagram for a typical chromic acid
anodizing process
Example of a single-sided lateral
exhaust hood
Example of a double-sided lateral
exhaust hood
Diagram of a push-pull ventilation
system
Horizontal-flow chevron-blade mist
eliminator with a single set of
blades
Horizontal-flow chevron-blade mist
eliminator with a double set of
blades ,
Blade designs for chevron-blade mist
eliminators
Mesh-pad mist eliminator
Horizontal-flow single packed-bed
scrubber
Horizontal-flow double packed-bed
scrubber
Fan-separator packed-bed scrubber
Centrifugal-flow scrubber ....
Effect of wetting agent on chromic
acid emissions ,
Page
3-3
3-5
3-7
3-12
3-20
4-4
4-4
4-5
4-9
4-10
4-11
4-14
4-18
4-19
4-22
4-25
4-29
Vlll
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LIST OF FIGURES (continued)
Page
Figure 4-13. Outlet concentration data for
chevron-blade mist eliminators 4-41
Figure 4-14. Outlet concentration data for mesh-pad
mist eliminators 4-49
Figure 4-15. Performance data for the packed-bed
scrubber at Plant I 4-54
Figure 4-16. Performance data for the packed-bed
scrubber at Plant L 4-61
Figure 4-17. Outlet concentration data for packed-bed
scrubbers 6-62
Figure 4-18. Performance data for chevron-blade mist
eliminators 4-70
Figure 4-19. Performance data for mesh-pad mist
eliminators and packed-bed scrubbers . . 4-72
Figure 4-20. Average control device efficiency versus
average inlet concentration for
scrubbers and mesh-pad mist
eliminators 4-73
Figure 4-21 Average control device efficiency
versus average Iog10 (concentration)
for scrubbers and mesh-pad mist
eliminators 4-73
Figure 4-22. Control device efficiency versus Iog10
(concentration) per test run for
two mesh-pad mist eliminator test
series 4-74
Figure 5-1. Frequency distribution of total tank
capacity for hard chromium plating ... 5-14
Figure 5-2. Frequency distribution of total tank
capacity for decorative chromium
plating 5-15
Figure 5-3. Schematic and ductwork specifications
for the small hard, small and medium
decorative chromium plating, and small
anodizing model tanks 5-16
ix
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LIST OF FIGURES (continued)
Page
Figure 5-4.
Figure 5-5a.
Figure 5-5b.
Figure 5-6.
Figure 5-7.
Figure 5-8.
Figure 5-9.
Figure 5-10.
Figure 8-1.
Schematic and ductwork specifications
of the medium and large hard chromium
plating model plants
(configuration 1)
Schematic and ductwork specifications
for one of the 12-foot tanks used in
the large decorative chromium plating
model plants (configurations 1 and 2) ,
Schematic and ductwork specifications of
two 12-foot tanks for the large
decorative chromium plating model
plants (configuration l) ,
Schematic and ductwork specifications
of the large chromic acid anodizing
model plants (configuration 1) ....
Schematic and ductwork specifications
for one of the 12-foot model tanks used
in the medium and large hard chromium
plating model plants
(configuration 2)
Schematic and ductwork specifications
for the 12-foot and 4-foot model tanks
used in the medium and large hard
chromium plating model plants
(configuration 2)
Schematic and ductwork specifications
for the 25-foot model tank used in
the medium and large hard chromium
plating model plants
(configuration 2)
Schematic and ductwork specifications
for the 30-foot model tank used in
the large chromic acid anodizing model
plant (configuration 2) ,
Electroplating, anodizing, and the
production process ,
5-17
5-18
5-19
5-20
5-21
5-22
5-23
5-24
8-3
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LIST OF TABLES
Page
TABLE 1-1. SUMMARY OF CONTROL OPTIONS 1-4
TABLE 1-2. ASSESSMENT OF ENVIRONMENTAL AND ECONOMIC
IMPACTS FOR EACH CONTROL OPTION
CONSIDERED FOR HARD CHROMIUM
ELECTROPLATING OPERATIONS 1-5
TABLE 1-3. ASSESSMENT OF ENVIRONMENTAL AND ECONOMIC
IMPACTS FOR EACH CONTROL OPTION
CONSIDERED FOR DECORATIVE CHROMIUM
ELECTROPLATING OPERATIONS 1-6
TABLE 1-4. ASSESSMENT OF ENVIRONMENTAL AND ECONOMIC
IMPACTS FOR EACH CONTROL OPTION
CONSIDERED FOR CHROMIC ACID
ANODIZING OPERATIONS 1-7
TABLE 1-5. NATIONWIDE CAPITAL AND NET ANNUALIZED COSTS
OF THE CONTROL OPTIONS FOR CHROMIUM
ELECTROPLATING AND CHROMIC ACID
ANODIZING OPERATIONS 1-8
TABLE 3-1. TYPICAL OPERATING PARAMETERS FOR HARD
CHROMIUM ELECTROPLATING 3-9
TABLE 3-2. TYPICAL OPERATING PARAMETERS FOR COPPER
PLATING BATHS 3-14
TABLE 3-3. TYPICAL OPERATING PARAMETERS FOR
DECORATIVE CHROMIUM PLATING 3-16
TABLE 3-4. CHROMIC ACID/SULFURIC ACID ETCH SOLUTION . . 3-18
TABLE 3-5. COLLOIDAL PALLADIUM ACTIVATING SOLUTION . . 3-18
TABLE 3-6. TYPICAL OPERATING PARAMETERS FOR CHROMIC
ACID ANODIZING 3-22
TABLE 3-7. HEXAVALENT AND TRIVALENT CHROMIUM
DEPOSIT COMPOSITIONS 3-26
TABLE 3-8. TANK PARAMETERS AND PROCESS OPERATING
PARAMETERS MONITORED DURING HARD
CHROMIUM PLATING TESTS 3-29
TABLE 3-9. TANK PARAMETERS AND PROCESS OPERATING
PARAMETERS MONITORED DURING DECORATIVE
CHROMIUM PLATING TESTS 3-29
XI
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LIST OF TABLES (continued)
Page
TABLE 3-10. UNCONTROLLED HEXAVALENT CHROMIUM
EMISSION DATA FROM HARD CHROMIUM
PLATING OPERATIONS 3-31
TABLE 3-11. UNCONTROLLED HEXAVALENT CHROMIUM
EMISSION DATA FROM DECORATIVE CHROMIUM
PLATING OPERATIONS 3-32
TABLE 3-12. PROCESS OPERATING PARAMETERS MONITORED
DURING SAMPLING AT THE CHROMIC ACID
ANODIZING FACILITY 3-38
TABLE 3-13. UNCONTROLLED CHROMIUM MASS EMISSION
RATES BASED ON HEXAVALENT AND TOTAL
CHROMIUM CONCENTRATION OF OUTLET
SCRUBBER WATER AT THE CHROMIC
ACID ANODIZING FACILITY 3-40
TABLE 4-1. MINIMUM VENTILATION RATES FOR VENTILATION
HOODS USED TO CAPTURE EMISSIONS OF
CHROMIC ACID MIST FROM CHROMIUM
PLATING AND CHROMIC ACID
ANODIZING TANKS 4-3
TABLE 4-2. TYPICAL OPERATING PARAMETERS FOR
PACKED-BED SCRUBBERS 4-20
TABLE 4-3. TYPICAL OPERATING PARAMETERS FOR
FAN-SEPARATOR PACKED-BED SCRUBBERS .... 4-23
TABLE 4-4a. SUMMARY OF EMISSION TEST RESULTS
FOR HEXAVALENT CHROMIUM (METRIC UNITS) . . 4-33
TABLE 4-4b. SUMMARY OF EMISSION TEST RESULTS FOR
HEXAVALENT CHROMIUM (ENGLISH UNITS) ... 4-34
TABLE 4-5. PERFORMANCE DATA FOR PLANT A 4-36
TABLE 4-6. PERFORMANCE DATA FOR PLANT B 4-38
TABLE 4-7. PERFORMANCE DATA FOR PLANT D 4-40
TABLE 4-8. PERFORMANCE DATA FOR CHEVRON-BLADE
MIST ELIMINATORS--PLANTS A, B, AND D
(AVERAGES) 4-41
TABLE 4-9. PERFORMANCE DATA FOR PLANT E 4-43
TABLE 4-10. PERFORMANCE DATA FOR PLANT F 4-45
Xl l
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LIST OF TABLES (continued)
Page
TABLE 4-11. PERFORMANCE DATA FOR PLANT G 4-48
TABLE 4-12. PERFORMANCE DATA FOR MESH-PAD
MIST ELIMINATORS--PLANTS E, F,AND G
(AVERAGES) 4-49
TABLE 4-13. PERFORMANCE DATA FOR PLANT I 4-53
TABLE 4-14. DIMENSIONS AND OPERATING PARAMETERS
OF HARD CHROMIUM PLATING TANKS 1, 2,
AND 4 TESTED AT PLANT K 4-55
TABLE 4-15. PERFORMANCE DATA FOR PLANT K 4-56
TABLE 4-16. PERFORMANCE DATA FOR PLANT L 4-60
TABLE 4-17. PERFORMANCE DATA FOR PACKED-BED
SCRUBBERS--PLANTS I, K, AND L
(AVERAGES) 4-62
TABLE 4-18. PERFORMANCE DATA FOR PLANT G--
POLYPROPYLENE BALLS 4-65
TABLE 4-19. PERFORMANCE DATA FOR PLANT N--
HEXAVALENT CHROMIUM EMISSIONS 4-68
TABLE 5-1. PARAMETERS FOR MODEL HARD CHROMIUM
ELECTROPLATING PLANTS 5-25
TABLE 5-2. PARAMETERS FOR MODEL DECORATIVE CHROMIUM
ELECTROPLATING PLANTS 5-26
TABLE 5-3. PARAMETERS FOR MODEL CHROMIC ACID
ANODIZING PLANTS 5-27
TABLE 5-4. MINIMUM VENTILATION RATES FOR VENTILATION
HOODS USED TO CAPTURE EMISSIONS OF CHROMIC
ACID MIST FROM CHROMIUM PLATING AND CHROMIC
ACID ANODIZING TANKS 5-28
TABLE 5-5. VENTILATION SPECIFICATIONS FOR
MODEL TANKS 5-29
TABLE 5-6. CONTROL DEVICE VENTILATION SPECIFICATIONS
FOR MODEL PLANTS 5-30
Xlll
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LIST OF TABLES (continued)
Page
TABLE 5-7. CONTROL DEVICE AND STACK PARAMETERS FOR
THE MODEL HARD CHROMIUM ELECTROPLATING
PLANTS 5-31
TABLE 5-8. CONTROL DEVICE AND STACK PARAMETERS FOR
THE MODEL DECORATIVE CHROMIUM
ELECTROPLATING PLANTS 5-32
TABLE 5-9. CONTROL DEVICE AND STACK PARAMETERS FOR
THE MODEL CHROMIC ACID ANODIZING
PLANTS 5-33
TABLE 5-10. BASELINE CONTROL LEVELS FOR CHROMIUM
PLATING AND CHROMIC ACID ANODIZING
OPERATIONS 5-34
TABLE 5-11. NUMBER OF OPERATIONS NATIONWIDE 5-35
TABLE 5-12. SUMMARY OF CONTROL OPTIONS 5-36
TABLE 6-1. CONTROL TECHNIQUES UPON WHICH THE
CONTROL OPTION ENVIRONMENTAL IMPACTS
ARE BASED 6-19
TABLE 6-2. NATIONWIDE HEXAVALENT CHROMIUM
EMISSION ESTIMATES ASSOCIATED WITH
CONTROL OPTIONS FOR HARD CHROMIUM
PLATING OPERATIONS 6-20
TABLE 6-3. NATIONWIDE EMISSION REDUCTIONS
ATTRIBUTABLE TO EACH CONTROL OPTION
FOR HARD CHROMIUM PLATING 6-21
TABLE 6-4. NATIONWIDE HEXAVALENT CHROMIUM
EMISSION ESTIMATES ASSOCIATED WITH
CONTROL OPTIONS FOR DECORATIVE
CHROMIUM PLATING OPERATIONS 6-22
TABLE 6-5. NATIONWIDE EMISSION REDUCTIONS
ATTRIBUTABLE TO EACH CONTROL OPTION
FOR DECORATIVE CHROMIUM PLATING 6-23
TABLE 6-6. NATIONWIDE HEXAVALENT CHROMIUM
EMISSION ESTIMATES ASSOCIATED WITH
CONTROL OPTIONS FOR CHROMIC ACID
ANODIZING OPERATIONS 6-25
xiv
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LIST OF TABLES (continued)
TABLE 6-7.
TABLE 6-8.
TABLE 6-9.
TABLE 6-10.
TABLE 6-11.
TABLE 6-12.
TABLE 6-13.
TABLE 6-14.
TABLE 6-15.
TABLE 7-1.
NATIONWIDE EMISSION REDUCTIONS
ATTRIBUTABLE TO EACH CONTROL OPTION
FOR CHROMIC ACID ANODIZING OPERATIONS
ANNUAL ENERGY REQUIREMENTS TO OPERATE
EACH CAPTURE SYSTEM USED FOR THE
PLATING AND ANODIZING MODEL PLANTS .
INCREASE IN ANNUAL ENERGY REQUIREMENTS
ATTRIBUTABLE TO CONTROL DEVICES
USED FOR THE PLATING AND ANODIZING
MODEL PLANTS
Page
6-26
6-27
NATIONWIDE ANNUAL ENERGY REQUIREMENTS
ASSOCIATED WITH CONTROL OPTIONS FOR
HARD CHROMIUM PLATING OPERATIONS . .
NATIONWIDE ANNUAL ENERGY REQUIREMENTS
ASSOCIATED WITH CONTROL OPTIONS FOR
DECORATIVE CHROMIUM PLATING
OPERATIONS .
6-28
6-30
NATIONWIDE ANNUAL ENERGY REQUIREMENTS
ASSOCIATED WITH CONTROL OPTIONS FOR
CHROMIC ACID ANODIZING OPERATIONS . . .
NATIONWIDE SOLID WASTE IMPACTS ASSOCIATED
WITH THE USE OF SINGLE PACKED-BED
SCRUBBERS AND MESH-PAD MIST
ELIMINATORS FOR HARD CHROMIUM
PLATING OPERATIONS .
6-31
6-33
6-34
NATIONWIDE SOLID WASTE IMPACTS ASSOCIATED
WITH THE USE OF SINGLE PACKED-BED
SCRUBBERS AND MESH-PAD MIST ELIMINATORS
FOR DECORATIVE CHROMIUM PLATING
OPERATIONS .
6-35
NATIONWIDE SOLID WASTE IMPACTS ASSOCIATED
WITH THE USE OF SINGLE PACKED-BED
SCRUBBERS AND MESH-PAD MIST ELIMINATORS
FOR CHROMIC ACID ANODIZING
OPERATIONS .
CONTROL TECHNIQUES UPON WHICH THE
CONTROL OPTION COST IMPACTS ARE BASED
6-37
7-43
XV
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LIST OF TABLES (continued)
Page
TABLE 7-2. CAPITAL AND ANNUALIZED COST DATA
SOURCES FOR POLLUTION CONTROL
TECHNIQUES 7-44
TABLE 7-3. ANNUAL OPERATING COST FACTORS 7-45
TABLE 7-4. COMPARATIVE PLATING LINE COST MODEL
USED TO DETERMINE COST DIFFERENTIAL
BETWEEN THE HEXAVALENT AND TRIVALENT
CHROMIUM PROCESSES 7-46
TABLE 7-5. HARD CHROMIUM ELECTROPLATING MODEL
PLANT PARAMETERS AND BASELINE
CONDITIONS 7-50
TABLE 7-6. CAPITAL COSTS OF CHEVRON-BLADE MIST
ELIMINATORS AND SINGLE PACKED-BED
SCRUBBERS FOR HARD CHROMIUM
PLATING MODEL PLANTS 7-52
TABLE 7-7. ANNUALIZED COSTS OF CHEVRON-BLADE MIST
ELIMINATORS AND SINGLE PACKED-BED
SCRUBBERS FOR HARD CHROMIUM
PLATING MODEL PLANTS 7-53
TABLE 7-8. CAPITAL COSTS OF MESH-PAD MIST
ELIMINATORS FOR HARD CHROMIUM
PLATING MODEL PLANTS 7-54
TABLE 7-9. ANNUALIZED COSTS FOR MESH-PAD MIST
ELIMINATORS FOR HARD CHROMIUM
PLATING MODEL PLANTS 7-55
TABLE 7-10. DECORATIVE CHROMIUM ELECTROPLATING
MODEL PLANT PARAMETERS AND BASELINE
CONDITIONS 7-56
TABLE 7-11. CAPITAL COSTS OF SINGLE PACKED-BED
SCRUBBERS FOR DECORATIVE CHROMIUM
ELECTROPLATING MODEL PLANTS 7-58
TABLE 7-12. ANNUALIZED COSTS OF SINGLE PACKED-BED
SCRUBBERS FOR DECORATIVE CHROMIUM
ELECTROPLATING MODEL PLANTS 7-59
TABLE 7-13. CAPITAL COSTS OF MESH-PAD MIST
ELIMINATORS FOR DECORATIVE CHROMIUM
ELECTROPLATING MODEL PLANTS 7-60
XVI
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LIST OF TABLES (continued)
TABLE 7-14.
TABLE 7-15.
TABLE 7-16.
TABLE 7-17.
TABLE 7-18.
TABLE 7-19.
TABLE 7-20.
TABLE 7-21.
TABLE 7-22.
TABLE 7-23.
ANNUALIZED COSTS OF MESH-PAD MIST
ELIMINATORS FOR DECORATIVE CHROMIUM
ELECTROPLATING MODEL PLANTS . . . .
Page
7-61
ANNUALIZED COSTS OF TEMPORARY AND
PERMANENT FUME SUPPRESSANTS FOR
DECORATIVE CHROMIUM ELECTROPLATING
MODEL PLANTS
7-62
INCREMENTAL CAPITAL COST ASSOCIATED WITH
INSTALLING A TRIVALENT CHROMIUM PROCESS
INSTEAD OF A HEXAVALENT CHROMIUM PROCESS
AT NEW DECORATIVE CHROMIUM ELECTROPLATING
FACILITIES
CAPITAL COST OF CONVERTING A HEXAVALENT
CHROMIUM PROCESS TO A TRIVALENT
CHROMIUM PROCESS AT EXISTING DECORATIVE
CHROMIUM ELECTROPLATING FACILITIES . . . ,
SCENARIO 1 - PLATING LINE COSTS FOR
EACH MODEL PLANT BASED ON THE
ACTUAL HEXAVALENT CHROMIUM REWORK
RATES
SCENARIO 2 - PLATING LINE COSTS FOR
EACH MODEL PLANT BASED ON THE
AVERAGE HEXAVALENT CHROMIUM REWORK
RATES ,
SCENARIO 3 - PLATING LINE COSTS FOR
EACH MODEL PLANT BASED ON THE
BREAK-EVEN HEXAVALENT CHROMIUM
REWORK RATES
7-63
7-64
7-65
7-69
CAPITAL RECOVERY COSTS FOR EACH
MODEL PLANT REPRESENTATIVE OF
BOTH NEW AND EXISTING FACILITIES
MODEL PLANT INCREMENTAL ANNUALIZED
COSTS ASSOCIATED WITH THE USE OF
THE TRIVALENT CHROMIUM PROCESS .
CHROMIC ACID ANODIZING MODEL PLANT
PARAMETERS AND BASELINE CONDITIONS
7-73
7-77
7-78
7-79
XVI1
-------
LIST OF TABLES (continued)
TABLE 7-24.
TABLE 7-25.
TABLE 7-26.
TABLE 7-27.
TABLE 7-28.
TABLE 7-29.
TABLE 7-30.
TABLE 7-31.
TABLE 7-32.
TABLE 7-33.
TABLE 7-34.
TABLE 7-35.
CAPITAL COSTS OF CHEVRON-BALDE MIST
MIST ELIMINATORS AND SINGLE PACKED-BED
SCRUBBERS FOR CHROMIC ACID ANODIZING
MODEL PLANTS
Page
7-80
ANNUALIZED COSTS OF CHEVRON-BLADE MIST
ELIMINATORS AND SINGLE PACKED-BED
SCRUBBERS FOR CHROMIC ACID ANODIZING
MODEL PLANTS
CAPITAL COSTS OF MESH-PAD MIST ELIMINATORS
FOR CHROMIC ACID ANODIZING MODEL PLANTS
ANNUALIZED COSTS OF MESH-PAD MIST
ELIMINATORS FOR CHROMIC ACID ANODIZING
MODEL PLANTS
ANNUALIZED COSTS OF PERMANENT FUME
SUPPRESSANTS FOR CHROMIC ACID ANODIZING
MODEL PLANTS
NATIONWIDE CAPITAL AND ANNUALIZED
COSTS FOR EACH CONTROL OPTION FOR
HARD CHROMIUM PLATING OPERATIONS .
COST EFFECTIVENESS OF THE CONTROL
OPTIONS FOR HARD CHROMIUM
ELECTROPLATING
NATIONWIDE CAPITAL AND ANNUALIZED COSTS
FOR EACH CONTROL OPTION FOR DECORATIVE
CHROMIUM ELECTROPLATING OPERATIONS ....
COST EFFECTIVENESS OF THE CONTROL OPTIONS
FOR DECORATIVE CHROMIUM ELECTROPLATING . .
NATIONWIDE CAPITAL AND ANNUALIZED
COSTS FOR EACH CONTROL OPTION FOR
CHROMIC ACID ANODIZING OPERATIONS ....
COST EFFECTIVENESS OF THE CONTROL
OPTIONS FOR CHROMIC ACID ANODIZING ....
ANNUALIZED HAZARDOUS WASTE TRANSPORTATION AND
DISPOSAL COSTS ATTRIBUTABLE TO THE CONTROL
OPTIONS BASED ON THE USE OF SINGLE
PACKED-BED SCRUBBERS OR MESH-PAD MIST
ELIMINATORS FOR HARD CHROMIUM PLATING
OPERATIONS
7-81
7-82
7-83
7-84
7-85
7-86
7-87
7-88
7-91
7-92
7-93
xvi 11
-------
TABLE 7-36
LIST OF TABLES (continued)
ANNUALIZED HAZARDOUS WASTE TRANSPORTATION
AND DISPOSAL COSTS ATTRIBUTABLE TO
THE CONTROL OPTIONS BASED ON THE USE
OF SINGLE PACKED-BED SCRUBBERS OR
MESH-PAD MIST ELIMINATORS FOR
DECORATIVE CHROMIUM PLATING OPERATIONS .
Page
7-94
TABLE 7-37. ANNUALIZED HAZARDOUS WASTE TRANSPORTATION
AND DISPOSAL COSTS ATTRIBUTABLE TO THE
CONTROL OPTIONS BASED ON THE USE OF
SINGLE PACKED-BED SCRUBBERS OR MESH-PAD
MIST ELIMINATORS FOR CHROMIC ACID
ANODIZING OPERATIONS 7-95
TABLE 7-38. CAPITAL COSTS OF VENTILATION HOODS
AND TAKEOFFS 7-96
TABLE 7-39. CAPITAL COSTS OF VENTILATION HOODS,
TAKEOFFS, AND DUCTWORK FOR EACH
CONTROL DEVICE 7-97
TABLE 7-40. CAPITAL COSTS OF VENTILATION HOODS,
TAKEOFFS, AND DUCTWORK FOR MODEL
PLANTS 7-98
TABLE 8-1. CHROMITE ORE END-USES 8-5
TABLE 8-2. U.S. DEMAND FOR CHROMIUM PLATING AS A
PERCENT OF TOTAL U.S. DEMAND FOR
CHROMITE ORE 8-6
TABLE 8-3. MAJOR SUPPLIERS OF CHROMIUM ELECTROPLATING
CHEMICAL SOLUTIONS 8-9
TABLE 8-4. FIRM SIZE DISTRIBUTION BY EMPLOYMENT .... 8-13
TABLE 8-5. GEOGRAPHICAL SUMMARY OF ELECTROPLATING ... 8-14
TABLE 8-6. PLUMBING FITTINGS AND BRASS GOODS
(SIC CODE 3432) : TRENDS 1982-1987 .... 8-19
TABLE 8-7. ANNUAL U.S. MOTOR VEHICLE PRODUCTION .... 8-22
TABLE 8-8. MANUFACTURERS' SHIPMENTS OF FLUID POWER
CYLINDERS AND ACTUATORS (SIC CODE 3593):
TRENDS 1982-1987 8-26
TABLE 8-9. OVERVIEW OF THE PRODUCTS SELECTED FOR
ANALYSIS 8-29
XIX
-------
LIST OF TABLES (continued)
TABLE 8-10,
TABLE 8-11,
TABLE 8-12,
TABLE 8-13
TABLE 8-14
TABLE 8-15
TABLE 8-16
TABLE 8-17,
TABLE 8-18
TABLE 8-19,
TABLE 8-20,
DECORATIVE CHROMIUM PLATING MODEL
PLANT COST DATA
HARD CHROMIUM PLATING MODEL PLANT
COST DATA
ESTIMATED PERCENT CHANGE IN ELECTROPLATING
COST, ESTIMATED PERCENT CHANGE IN FINAL
PRICE, AND ESTIMATED DOLLAR AMOUNT CHANGE
IN THE FINAL PRICE DUE TO VARIOUS CONTROL
OPTIONS: KITCHEN FAUCETS ,
Page
8-33
8-35
PARAMETRIC VALUES OF THREE HAND TOOLS . . .
ESTIMATED PERCENT CHANGE IN CHROMIUM
ELECTROPLATING COST, ESTIMATED PERCENT
CHANGE IN THE FINAL PRICE, AND ESTIMATED
DOLLAR AMOUNT CHANGE IN THE FINAL PRICE DUE
TO VARIOUS CONTROL OPTIONS: THREE
HAND TOOLS
LIST OF AUTOMOBILE PARTS TYPICALLY
CHROMIUM ELECTROPLATED
8-39
8-42
8-43
8-45
ESTIMATED PERCENT CHANGE IN ELECTROPLATING
COST, ESTIMATED PERCENT CHANGE IN THE FINAL
PRICE, AND ESTIMATED DOLLAR AMOUNT CHANGE
IN THE FINAL PRICE DUE TO VARIOUS CONTROL
OPTIONS: DECORATIVE CHROMIUM PARTS IN
REPRESENTATIVE AUTOMOBILE
ESTIMATED PERCENT CHANGE IN ELECTROPLATING
COST, ESTIMATED PERCENT CHANGE IN THE FINAL
PRICE, AND ESTIMATED DOLLAR AMOUNT CHANGE
IN THE FINAL PRICE DUE TO VARIOUS CONTROL
OPTIONS: HARD CHROMIUM PARTS FOR
REPRESENTATIVE AUTOMOBILE
ESTIMATED CHANGE IN THE FINAL PRICE PER
AUTOMOBILE DUE TO THE VARIOUS CONTROL
OPTIONS: SUM OF BOTH HARD AND
DECORATIVE CHROMIUM PARTS FOR
REPRESENTATIVE AUTOMOBILE
8-49
8-51
PARAMETRIC VALUES: INDUSTRIAL ROLLS . . . .
ANNUAL PLANT OUTPUT: INDUSTRIAL ROLLS . . .
8-52
8-54
8-56
xx
-------
LIST OF TABLES (continued)
Page
TABLE 8-21. ESTIMATED ELECTROPLATING COST PER PLANT
PER YEAR: INDUSTRIAL ROLLS ....... 8-57
TABLE 8-22. ESTIMATED PERCENT CHANGE IN THE HARD
CHROMIUM ELECTROPLATING COST DUE TO THE
VARIOUS CONTROL OPTIONS: INDUSTRIAL ROLLS
WITH DIFFERING COST FACTORS 8-58
TABLE 8-23. LIST OF TYPICAL HARD CHROMIUM ELECTROPLATED
BACKHOE CYLINDERS 8-60
TABLE 8-24. OUTPUT PER PLANT PER YEAR AT 80 PERCENT
CAPACITY: BACKHOE CYLINDER 8-61
TABLE 8-25. ESTIMATED ANNUAL CHROMIUM ELECTROPLATING
COST: BACKHOE CYLINDERS 8-62
TABLE 8-26. ESTIMATED PERCENT CHANGE IN THE COST OF HARD
CHROMIUM ELECTROPLATING DUE TO THE VARIOUS
CONTROL OPTIONS: HYDRAULIC CYLINDERS FOR
BACKHOES WITH DIFFERING COST FACTORS ... 8-63
TABLE 8-27. ESTIMATED DOLLAR AND PERCENT CHANGE IN THE
FINAL PRICE DUE TO THE VARIOUS CONTROL
OPTIONS: BACKHOES 8-65
TABLE 8-28. ESTIMATED PERCENT CHANGE IN THE COST OF
CHROMIC ACID ANODIZING DUE TO THE
VARIOUS CONTROL OPTIONS 8-66
TABLE 8-29. ESTIMATED PERCENT CHANGES IN QUANTITY AND
REVENUE FOR EACH OF THE PRODUCTS
SELECTED FOR ANALYSIS 8-69
TABLE 8-30. CONTROL COST PER AMPERE HOUR FOR HARD
CHROMIUM ELECTROPLATING 8-74
TABLE 8-31. CAPITAL AVAILABILITY ANALYSIS FOR SMALL
CHROMIUM ELECTROPLATING FIRM 8-75
TABLE 8-32. NUMBER OF PLANTS, PLANT SIZE, INDUSTRY
CAPACITY, AND PERCENT OF INDUSTRY
CAPACITY--HARD CHROMIUM ELECTROPLATERS . . 8-82
TABLE 8-33. NUMBER OF SMALL PLANT CLOSURES BASED ON
PERCENT PRICE INCREASE AND ELASTICITY
VALUE COMPARISONS 8-83
xxi
-------
ABBREVIATIONS USED IN THIS DOCUMENT
A
acfm
acmm
Ah
ANSI
atm
BACT
BID
CAA
cm
cm2
cm3
°C
Cr
Cr2
Cr6
Cr03
AP
dscf
dscfm
dscm
EO
oF
ft
ft2
ft3
g
GACT
gal
gal/min
hr
hp
in.
ampere
actual cubic feet per minute
actual cubic meters per minute
ampere-hour
American National Standards Institute
atmospheres
best available control technology
background information document
Clean Air Act
centimeter
square centimeter
cubic centimeter
degrees centigrade
chromium
chromium (II)
hexavalent chromium
chromium anhydride, commonly known as chromic acid
pressure drop
dry standard cubic foot
dry standard cubic feet per minute
dry standard cubic meter
Executive Order
degrees Fahrenheit
foot
square foot
cubic foot
gram
generally available control technology
gallon
gallons per minute
grain
hour
horsepower
inch
xxn
-------
in."
in. w.c
kg
kPa
kW
L
L/G
LAER
Ib
lbf/ft
m
m2
m3
MACT
mg
Mg
mil -
min
MW
NEPA
NESHAP
ng
NSPS
OSHA
OZ
P
psi
PVC
RACT
RCRA
RFA
RIA
SIC
square inch
inches of water column
kilogram
kilopascal
kilowatt
liter
liquid to gas [ratio]
lowest achievable emission rate
pound
pound force per foot
meter
square meter
cubic meter
maximum available control technology
milligram
megagram
thousandth of an inch
minute
megawatt
microgram
micrometer
National Environmental Policy Act
national emission standards for hazardous air
pollutants
nanogram
new source performance standard
Occupational Safety and Health Administration
ounce
pressure
pounds per square inch
polyvinyl chloride
reasonably available control technology
Resource Conservation and Recovery Act
Regulatory Flexibility Act
Regulatory Impact Analysis
Standard Industrial Classification (code)
XXlll
-------
TLV = threshold limit value
V = volt
wt = weight
yr = year
xxiv
-------
GLOSSARY OF ELECTROPLATING TERMS
Activation:
Ampere:
Anion:
Anode:
Anodizing:
Baffle:
Base metal:
Brightener:
Bright plating:
Buffing:
Process in which the conductivity
of the part to be plated is
increased.
Current flowing at a rate of one
coulomb per second.
A negatively charged ion.
The electrode at which current
enters or electrons leave the
solution; also, the positive
electrode at which negative ions
are discharged, positive ions are
formed, or at which other oxidizing
reactions occur.
A surface treatment of metals,
particularly aluminum; the part to
be plated serves as the anode and
an oxide film is produced as an
integral part of the base metal.
A device used to regulate the flow
of gas by deflecting the gas.
The underlying metal or alloy
system onto which the plated metal
is deposited; for example, in the
chromium electroplating of steel in
the automotive industry, the steel
is the base metal.
An agent added to electroplating
baths that helps form a bright
plate or improves the brightness of
the deposit.
Electroplating to provide a highly
brilliant or polished-appearing
surface; most decorative plating is
done with brighteners.
Smoothing a surface using fine
abrasive particles in liquid
suspension, paste, or grease stick
form.
XXV
-------
Burnt deposit:
Bus (bus bar) :
Capture efficiency:
Capture velocity:
Cathode:
Cathode efficiency:
Cation:
Chemical fume suppressants
Chromic acid:
Cleaning:
A rough, noncoherent, or otherwise
unsatisfactory deposit produced by
the application of excessive
current density and usually
containing oxides or other
inclusions.
A rigid conducting section, usually
copper, for carrying current to the
anode and cathode bars.
A measure of the effectiveness of a
ventilation system to overcome
opposing air currents and direct
contaminated air from the process
vessel into the ventilation hood.
Air velocity at any point in front
of the ventilation hood or at the
hood opening necessary to overcome
opposing air currents and to
capture the contaminated air at
that point by causing it to flow
into the hood.
The electrode through which current
leaves or electrons enter the
solution; the negative electrode.
Also, the electrode at which
positive ions are discharged,
negative ions are formed, or other
reducing reactions occur. In
electroplating, the cathode
typically is the workpiece to be
plated.
The current efficiency of a
specified cathodic process.
A positively charged ion.
Surface-active compounds that
reduce or suppress fumes at the
surface of a solution.
The common name for chromium
anhydride (Cr03).
The removal of grease or other
foreign material from the surface
of a part.
xxvi
-------
Alkaline:
Anodic (reverse):
Cathodic (direct)
Emulsion:
Soak:
Solvent:
Colloidal particle:
Coloring (color buffing)
Complexing agent:
Conversion coating:
Correlation coefficient(r)
Coulomb:
Covering power:
Cleaning by means of an alkaline
solution.
Electrolytic cleaning in which the
workpiece is the anode.
Electrolytic cleaning in which the
workpiece is the cathode.
Cleaning by means of solutions
containing organic solvents, water,
and emulsifying agents.
Alkaline cleaning without the use
of current.
Cleaning by means of organic
solvents.
An electrically charged particle,
generally smaller than
200 millimicrons, dispersed in a
second phase.
Light buffing of metal surfaces to
produce a high luster.
A compound capable of forming a
complex ion with a metal ion.
A coating produced by chemical or
electrochemical treatment of a
metallic surface that gives a
superficial layer of a compound of
the metal.
A measure of interdependence of two
random variables that range in
value from -1 to +1. The perfect
negative correlation is indicated
at -1, absence of correlation at 0,
and perfect positive correlation at
+1.
The quantity of electricity which
passes any section of an electric
circuit in one second when the
current in the circuit is one
ampere.
The ability of a plating solution
to produce a deposit at very low
current densities.
xxvi i
-------
Current density:
Current efficiency:
Decorative chromium plating:
Degreasing:
Solvent:
Vapor:
Desmut:
Detergent:
Anionic:
Cationic:
Nonionic:
Dielectric:
A measure of the flow of ionic
species at the electrodes.
Expressed as amperes per square
foot, this is one of several
important process parameters in the
control of the overall
electroplating operation. Current
density is equal to the total
current divided by the total area
of the electrode in the solution.
Percentage of applied current used
to deposit metal on a part being
plated; remaining current is used
in side reactions.
Chromium plating for decorative
purposes.
The removal of grease and oils from
a surface.
Degreasing by immersion in liquid
organic solvents.
Degreasing by solvent vapors
condensing on the parts being
plated.
The removal of soil or grease films
that cleaners and etchants leave
behind.
A surface-active agent that can
clean soiled surfaces.
A detergent that produces
aggregates of negatively charged
ions with colloidal properties.
A detergent that produces
aggregates of positively charged
ions with colloidal properties.
A detergent that produces
aggregates of electrically neutral
molecules with colloidal
properties.
A material or medium that does not
conduct electricity and that can
sustain an electrical field.
XXVlll
-------
Dielectric strength;
Direct interception:
Drag-in:
Drag-out:
Dummy:
Dummying:
Effluent:
Electrochemical equivalent:
Electrochemistry:
Electrodeposition:
Electroless plating:
The maximum potential gradient that
a dielectric material can withstand
without rupture.
Collection of particles, due to
their size and relative velocity,
by interception with a fluid
boundary around the collection
surface.
The water or solution that adheres
to objects introduced into a bath.
The water or solution that adheres
to objects removed from a bath.
A cathode in a plating tank that is
used for working the solution but
that is not to be used after
plating.
Plating with dummy cathodes.
Liquid which flows away from a
contained space or a main waterway.
The weight of an element, compound,
radical, or ion involved in a
specified electrochemical reaction
during the passage of a unit
quantity of electricity, such as a
Faraday.
The science that deals with the use
of electrical energy to bring about
a chemical reaction and the use of
chemical action to generate
electrical energy.
The process of depositing a
substance upon an electrode by
electrolysis. Includes
electroplating.
Depositing of a metallic coating by
a controlled chemical reduction,
which is catalyzed by the metal or
alloy being deposited.
XXIX
-------
Electrolyte:
Electrolysis:
Electroplating:
Face velocity:
Faraday:
Faraday's Law:
Frequency distribution:
Grinding:
Hard chromium plating:
A conducting medium in which the
flow of current is accompanied by
movement of matter. Most often an
aqueous solution of acids, bases,
or salts but includes many other
media such as fused salts, ionized
gases, some solids, etc.
Production of chemical changes by
the passage of current through an
electrolyte.
The electrodeposition of an
adherent metallic coating upon an
electrode (workpiece) to obtain a
surface with properties or
dimensions different from those of
the base metal.
The velocity of the gas stream
across the face (front) of a given
surface.
The number of coulombs (96,490)
required for an electrochemical
reaction involving one chemical
equivalent.
(1) The amount of any substance
dissolved or deposited in
electrolysis is proportional to the
total electric charge passed.
(2) The amounts of different
substances dissolved or deposited
by the passage of the same electric
charge are proportioned to their
equivalent weights.
A function that measures the
relative frequency or probability
that a variable can take on a set
of values.
The removal of metal by means of
rotating rigid wheels containing
abrasives.
Chromium plating for engineering or
functional purposes rather than
decorative applications.
XXX
-------
Heat exchanger:
Hexavalent chromium:
Horsepower:
Inertial impaction:
Influent:
Inlet loading:
Ion:
Kilowatt:
Kilowatt-hour:
Leveling action:
Linear regression:
Liquid-to-gas ratio:
Any device that transfers heat from
one fluid to another or to the
environment.
The form of chromium in a valence
state of + 6.
The unit of power in the British
engineering system equal to
550 foot-pounds per second,
approximately 745.7 watts.
Collection of particles by their
collision with and adhesion to a
stationary surface.
A input stream of a fluid into a
contained space or main waterway.
Uncontrolled concentration of the
pollutant.
An atom or group of atoms which has
lost or gained one or more
electrons, thereby acquiring a net
electrical charge.
A unit of power equal to
1,000 watts.
A unit of energy or work equal to
1,000 watt-hours.
The ability of a plating solution
to produce a smoother surface than
that of a base metal.
The straight line running among the
points of a scatter diagram and
about which the amount of scatter
is smallest.
A design operating parameter for
scrubbers that is set at a value to
optimize performance. It is the
amount of liquid flow compared to
the gas flow, expressed in liters
per minute to 1,000 cubic meters
per minute.
XXXI
-------
Mist eliminator:
Oxidation:
Packed bed:
Passivation:
Periodic reverse:
Polishing:
Polypropylene:
Pressure drop:
Rack:
Rectifier:
A device that removes liquid mist
or droplets from a gas stream via
impingement, flow-direction change,
velocity change, centrifugal force,
filters, or coalescing packs.
A reaction in which electrons are
removed from a reactant.
A fixed layer of small particles or
objects arranged in a vessel to
promote intimate contact between
gases, vapors, liquids, solids, or
various combinations thereof.
The treatment of a metal to form a
protective coating on its surface
and reduce its chemical activity.
A method of plating in which the
current is reversed periodically.
Smoothing a metal surface with
abrasive particles attached by
adhesive to the surface of wheels
or belts.
A crystalline, thermoplastic resin
made by the polymerization of
propylene. The product is hard and
tough; resists moisture, oils, and
solvents; and withstands
temperatures up to 170 degrees
centigrade.
The difference in pressure between
two points in a flow system,
usually caused by fractional
resistance to a fluid or gas
flowing through a conduit, filter
media, or other flow-conducting
system.
A frame for suspending articles
during plating and related
operations.
A device which converts alternating
current into direct current by
permitting appreciable flow of
current in one direction.
XXXI1
-------
Reduction:
Reentrainment:
Reentrainment velocity:
Scrubber:
Shield:
Slot velocity:
Smut:
Strike:
Surface active agent:
Surface tension:
Tarnish:
Thermocouple:
A chemical reaction in which
electrons are added to the
reactant.
Reentry into the gas stream of
previously collected particles.
The velocity at which particle
reentry occurs.
A device that removes entrained
liquid droplets, dust, or an
undesired gas component from the
process gas stream via impaction or
direct interception.
To alter the normal current
distribution on an anode or cathode
by the interposition of a
nonconductor.
Air velocity through the openings
in a slot-type hood. It is used
primarily as a means of obtaining
air distribution across the face of
the hood.
Anything that fouls or soils the
external surface of the base metal
in electroplating processes;
removal of smut is a critical
initial step in the electroplating
process.
A solution used to deposit a thin
initial film of metal.
A soluble or colloidal substance
that affects markedly the surface
energy of solutions even when
present in very low concentrations.
The property, due to molecular
forces, that exists in the surface
film of all liquids and tends to
prevent liquid from spreading.
Dulling, staining, or discoloration
of metals due to superficial
corrosion.
A device that is used to measure
temperature.
xxxi11
-------
Throwing power:
Trivalent chromium:
Volt:
Watt:
Wetting agent:
Workload:
Workpiece:
The improvement of the coating
distribution ratio over the primary
current distribution ratio on an
electrode. Also, a measure of the
degree of uniformity with which
metal is deposited on an
irregularly shaped cathode.
The form of chromium in a valence
state of +3.
The electromotive force that will
produce a current of one ampere
through a resistance of one ohm.
The unit of power in the metric
system of units, equal to one joule
per second.
A substance that reduces the
surface tension of a liquid,
thereby causing it to spread more
readily on a solid surface.
The amount of work in the process
tank at a given time.
The material being plated or
otherwise finished.
xxxiv
-------
1. SUMMARY
National emission standards for hazardous air pollutants
(NESHAP) are established under Section 112 of the Clean Air Act
(CAA) (P.L. 101-459), as amended in 1990. Section 112(b)
contains a list of hazardous air pollutants (HAP's), which are
the specific air toxics regulated by NESHAP. Section 112(c)
directs the Administrator to use this pollutant list to develop
and publish a list of source categories for which NESHAP will be
developed. Chromium electroplating operations are included on
this source category list and were selected by EPA for NESHAP
development based on their "threat of adverse effects to health
and the environment."
This background information document (BID) supports proposed
standards for hard and decorative chromium electroplating and
chromic acid anodizing operations. These operations are
significant emitters of chromic acid, the principal constituent
of chromium electroplating and anodizing baths. Chromic acid is
a hexavalent chromium compound, and chromium compounds are
included in the list of HAP's. Chromium electroplating and
anodizing operations typically are located in or near industrial
centers in areas of high population density.
1.1 CONTROL OPTIONS
Table 1-1 is a summary of the control options for chromium
electroplating and chromic acid anodizing operations. Each
control option represents a different level of emission control.
The level of control assigned to each control technique is based
on the percent emission reduction achievable by well-maintained
units at average inlet loadings for each type of operation. For
each type of operation, Option 1 is the "no action" or baseline
1-1
-------
option. The "no action" option reflects the level of control
achieved at existing operations in the absence of further
regulation. The control options, together with the newer
technologies described in the document Technical Assessment of
Innovative Emission Control Technologies Used in the Chromium
Electroplating Industry form the basis of the proposed regulatory
alternatives for chromium electroplating and chromic acid
anodizing operations.
1.2 ENVIRONMENTAL IMPACT
Tables 1-2, 1-3, and 1-4 summarize the environmental and
economic impacts associated with the control options for the hard
chromium electroplating, decorative chromium electroplating, and
chromic acid anodizing source categories.
1.2.1 Hard Chromium Electroplating Operations
Control Option II for hard chromium electroplating
operations would reduce nationwide chromium air emissions from
the baseline level of 145 Mg/yr (160 tons/yr) to 18 Mg/yr
(20 tons/yr). Control Options Ilia and Illb would further reduce
these emissions to 4.2 Mg/yr (4.7 tons/yr).
As shown in Table 1-2, the reduction in nationwide chromium
emissions associated with either of the control options would
result in minimal adverse environmental impacts. There would be
a negligible increase in solid waste attributable to Control
Options Ilia and Illb. Control Option II, Ilia, or Illb would
cause a slight increase in energy consumption due to the
additional energy requirements for fans, when chevron-blade mist
eliminators are used, and fans and recirculation pumps, when
packed-bed scrubbers are mesh-pad mist eliminators are used.
1.2.2 Decorative Chromium Electroplating Operations
Control Options Ila and lib for decorative chromium
electroplating operations would reduce nationwide chromium air
emissions from the baseline level of 10 Mg/yr (11 tons/yr) to
1.7 Mg/yr (1.9 tons/yr). Control Option III would reduce
chromium emissions to 0.29 Mg/yr (0.32 ton/yr). Control
Option IV, which involves the substitution of a trivalent
chromium plating bath for the conventional hexavalent chromium
1-2
-------
plating bath, would eliminate hexavalent chromium emissions from
these operations.
As can be seen in Table 1-3, the reduction in nationwide
chromium emissions associated with Control Options Ila and lib
results in a negligible increase .in solid waste. The slight
increase in energy consumption is due to the additional fan and
pump horsepower required to operate packed-bed scrubbers or
mesh-pad mist eliminators. No environmental impacts are
associated with the reduction in nationwide chromium emissions
achieved under Control Option III. Control Option IV results in
beneficial environmental impacts with decreases in solid waste
and energy usage. Control Option IV has a beneficial impact on
water pollution because the use of the more toxic hexavalent
solution is eliminated.
1.2.3 Chromic Acid Anodizing Operations
Control Options Ila and lib for chromic acid anodizing
operations would reduce nationwide chromium air emissions from a
baseline level of 3.6 Mg/yr (3.9 tons/yr) to 0.25 Mg/yr
(0.28 ton/yr). Control Option III would further reduce chromium
emissions to 0.04 Mg/yr (0.05 ton/yr).
As shown in Table 1-4, only minimal adverse environmental
impacts are associated with Control Options Ila and lib. There
would be a negligible increase in solid waste and a slight
increase in energy consumption (due to the increase in fan and
pump horsepower requirements). No environmental impacts are
associated with the reduction in nationwide chromium emissions
attributable to Control Option III.
1.3 ECONOMIC IMPACT
An overview of the economic impacts of the control options
for chromium electroplating and chromic acid anodizing operations
is presented in Tables 1-2, 1-3, and 1-4. Table 1-5 shows the
nationwide capital and net annualized costs associated with each
of the control options. Analyses of the costs and economic
impacts are presented in Chapters 7 and 8.
1-3
-------
TABLE 1-1. SUMMARY OF CONTROL OPTIONS
Type of operation/
Control option
Control technique
Hard chromium plating
Option I (no action)
Option n
Option in
Decorative chrnrnium plating
Option I (no action)
Option II
Option m
Option IV
Chromic acid anodizing
Option I (no action)
Option
Option
Existing (baseline) level of control
• 30 percent of operations uncontrolled
• 30 percent of operations controlled by chevron-blade mist eliminators that
reduce uncontrolled emissions by 90 percent
• 40 percent of operations controlled by packed-bed scrubbers that reduce
uncontrolled emissions by 97 percent
Chevron-blade mist eliminators that reduce uncontrolled emissions
by 95 percent
Packed-bed scrubbers or mesh-pad mist eliminators that reduce uncontrolled
emissions by 99 percent
Existing (baseline) level of control
• IS percent of operations uncontrolled
• 40 percent of operations controlled by chemical fume suppressants that
reduce uncontrolled emissions by 97 percent
• 40 percent of operations controlled by a combination of chemical fume
suppressants and packed-bed scrubbers that reduces uncontrolled emissions
by 97 percent
• 5 percent of operations controlled by packed-bed scrubbers that reduce
uncontrolled emissions by 95 percent
Packed-bed scrubbers or mesh-pad mist eliminators that reduce uncontrolled
emissions by 97 percent
Chemical fume suppressants applied in accordance with vendor
recommendations. Uncontrolled emissions reduced by 99.5 percent
Trivalent chromium plating processes that reduce hexavalent chromium
emissions by 100 percent (technology forcing)
Existing (baseline) level of control
• 40 percent of operations uncontrolled
• 30 percent of operations controlled by chemical fume suppressants that
reduce uncontrolled emissions by 97 percent
• 10 percent of operations controlled by chevron-blade mist eliminators that
reduce uncontrolled emissions by 90 percent
• 20 percent of operations controlled by packed-bed scrubbers that reduce
uncontrolled emissions by 95 percent.
Packed-bed scrubbers or mesh-pad mist eliminators that reduce uncontrolled
emissions by 97 percent
Chemical fume suppressants applied in accordance with vendor
recommendations. Uncontrolled emissions reduced by 99.5 percent
1-4
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-------
2. INTRODUCTION
2.1 BACKGROUND AND AUTHORITY FOR STANDARDS
According to industry estimates, more than 2.4 billion
pounds of toxic pollutants were emitted to the atmosphere in 1988
(Implementation Strategy for the Clean Air Act Amendments of
1990. EPA Office of Air and Radiation, January 15, 1991) . These
emissions may result in a variety of adverse health effects,
including cancer, reproductive effects, birth defects, and
respiratory illnesses. Title III of the Clean Air Act Amendments
of 1990 provides the tools for controlling emissions of these
pollutants. Emissions from both large and small facilities that
contribute to air toxics problems in urban and other areas will
be regulated. The primary consideration in establishing national
industry standards must be demonstrated technology. Before
national emission standards for hazardous air pollutants (NESHAP)
are proposed as Federal regulations, air pollution prevention and
control methods are examined in detail with respect to their
feasibility, environmental impacts, and costs. Various control
options based on different technologies and degrees of efficiency
are examined, and a determination is made regarding whether the
various control options apply to each emissions source or if
dissimilarities exist between the sources. In most cases,
regulatory alternatives are subsequently developed that are then
studied by EPA as a prospective basis for a standard. The
alternatives are investigated in terms of their impacts on the
environment, the economics and well-being of the industry, the
national economy, and energy and other impacts. This document
summarizes the information obtained through these studies so that
2-1
-------
interested persons will be able to evaluate the information
considered by EPA in developing the proposed standards.
National emission standards for hazardous air pollutants for
new and existing sources are established under Section 112 of the
Clean Air Act as amended in 1990 [42 U.S.C. 7401 et seq., as
amended by PL 101-549, November 15, 1990], hereafter referred to
as the Act. Section 112 directs the EPA Administrator to
promulgate standards that "require the maximum degree of
reduction in emissions of the hazardous air pollutants subject to
this section (including a prohibition of such emissions, where
achievable) that the Administrator, taking into consideration the
cost of achieving such emission reductions, and any non-air
quality health and environmental impacts and energy requirements,
determines is achievable ... ." The Act allows the Administrator
to set standards that "distinguish among classes, types, and
sizes of sources within a category or subcategory."
The Act differentiates between major sources and area
sources. A major source is defined as "any stationary source or
group of stationary sources located within a contiguous area and
under common control that emits or has the potential to emit
considering controls, in the aggregate, 10 tons per year or more
of any hazardous air pollutant or 25 tons per year or more of any
combination of hazardous air pollutants." The Administrator,
however, may establish a lesser quantity cutoff to distinguish
between major and area sources. The level of the cutoff is based
on the potency, persistence, or other characteristics or factors
of the air pollutant. An area source is defined as "any
stationary source of hazardous air pollutants that is not a major
source." For new sources, the amendments state that the "maximum
degree of reduction in emissions that is deemed achievable for
new sources in a category or subcategory shall not be less
stringent than the emission control that is achieved in practice
by the best controlled similar source, as determined by the
Administrator." Emission standards for existing sources:
2-2
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may be less stringent than the standards for new
sources in the same category or subcategory but shall
not be less stringent, and may be more stringent than--
(A) the average emission limitation achieved
by the best performing 12 percent of the
existing sources (for which the Administrator
has emissions information), excluding those
sources that have, within 18 months before
the emission standard is proposed or within
30 months before such standard is
promulgated, whichever is later, first
achieved a level of emission rate or emission
reduction which complies, or would comply if
the source is not subject to such standard,
with the lowest achievable emission rate (as
defined by Section 171) applicable to the
source category and prevailing at the time,
in the category or subcategory for categories
and subcategories with 30 or more sources, or
(B) the average emission limitation achieved
by the best performing five sources (for
which the Administrator has or could
reasonably obtain emissions information) in
the category or subcategory for categories or
subcategories with fewer than 30 sources.
The Federal standards are also known as "MACT" standards and
are based on the maximum achievable control technology previously
discussed. The MACT standards apply to both major and area
sources, although the existing source standards may be less
stringent than the new source standards, within the constraints
presented above. The MACT is considered to be the basis for the
standard, but the Administrator may promulgate more stringent
standards than the MACT floor, which have several advantages.
First, they may help achieve long-term cost savings by avoiding
the need for more expensive retrofitting to meet possible future
residual risk standards, which may be more stringent (discussed
in Section 2.7). Second, Congress was clearly interested in
providing incentives for improving technology. Finally, in the
Clean Air Act Amendments of 1990, Congress gave EPA a clear
mandate to reduce the health and environmental risk of air toxics
emissions as quickly as possible.
2-3
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For area sources, the Administrator may "elect to promulgate
standards or requirements applicable to sources in such
categories or subcategories which provide for the use of
generally available control technologies or management practices
by such sources to reduce emissions of hazardous air pollutants."
These area source standards are also known as "GACT" (generally
available control technology) standards, although MACT may be
applied at the Administrator's discretion, as discussed
previously.
The standards for hazardous air pollutants (HAP's), like the
new source performance standards (NSPS) for criteria pollutants
required by Section 111 of the Act (42 U.S.C. 7411), differ from
other regulatory programs required by the Act (such as the new
source review program and the prevention of significant
deterioration program) in that NESHAP and NSPS are national in
scope (versus site-specific). Congress intended for the NESHAP
and NSPS programs to provide a degree of uniformity to State
regulations to avoid situations where some States may attract
industries by relaxing standards relative to other States.
States are free under Section 116 of the Act to establish
standards more stringent than Section 111 or 112 standards.
Although NESHAP are normally structured in terms of
numerical emissions limits, alternative approaches are sometimes
necessary. In some cases, physically measuring emissions from a
source may be impossible or at least impracticable due to
technological and economic limitations. Section 112(h) of the
Act allows the Administrator to promulgate a design, equipment,
work practice, or operational standard, or combination thereof,
in those cases where it is not feasible to prescribe or enforce
an emissions standard. For example, emissions of volatile
organic compounds (many of which may be HAP's, such as benzene)
from storage vessels for volatile organic liquids are greatest
during tank filling. The nature of the emissions (i.e., high
concentrations for short periods during filling and low
concentrations for longer periods during storage) and the
configuration of storage tanks make direct emission measurement
2-4
-------
impractical. Therefore, the MACT or GACT standards may be based
on equipment specifications.
Under Section 112(h)(3), the Act also allows the use of
alternative equivalent technological systems: "If, after notice
and opportunity for comment, the owner or operator of any source
establishes to the satisfaction of the Administrator that an
alternative means of emission limitation" will reduce emissions
of any air pollutant at least as much as would be achieved under
the design, equipment, work practice, or operational standard,
the Administrator shall permit the use of the alternative means.
Efforts to achieve early environmental benefits are
encouraged in Title III. For example, source owners and
operators are encouraged to use the Section 112(i)(5) provisions,
which allow a 6-year compliance extension of the MACT standard in
exchange for the implementation of an early emission reduction
program. The owner or operator of an existing source must
demonstrate a 90 percent emission reduction of HAP's (or
95 percent if the HAP's are particulates) and meet an alternative
emission limitation, established by permit, in lieu of the
otherwise applicable MACT standard. This alternative limitation
must reflect the 90 (95) percent reduction and is in effect for a
period of 6 years from the compliance date for the otherwise
applicable standard. The 90 (95) percent early emission
reduction must be achieved before the otherwise applicable
standard is first proposed, although the reduction may be
achieved after the standard's proposal (but before January 1,
1994) if the source owner or operator makes an enforceable
commitment before the proposal of the standard to achieve the
reduction. The source must meet several criteria to qualify for
the early reduction standard, and Section 112(i)(5)(A) provides
that the State may require additional reductions.
2.2 SELECTION OF POLLUTANTS AND SOURCE CATEGORIES
As amended in 1990, the Act includes a list of 190 HAP's.
Petitions to add or delete pollutants from this list may be
submitted to EPA. Using this list of pollutants, EPA will
publish a list of source categories (major and area sources) for
2-5
-------
which emission standards will be developed. Within 2 years of
enactment (November 1992), EPA will publish a schedule
establishing dates for promulgating these standards. Petitions
may also be submitted to EPA to remove source categories from the
list. The schedule for standards.for source categories will be
determined according to the following criteria:
(A) The known or anticipated adverse effects of such
pollutants on public health and the environment;
(B) The quantity and location of emissions or
reasonably anticipated emissions of HAP's that each
category or subcategory will emit; and
(C) The efficiency of grouping categories or
subcategories according to the pollutants emitted or
the processes or technologies used.
After the source category has been chosen, the types of
facilities within the source category to which the standard will
apply must be determined. A source category may have several
facilities that cause air pollution, and emissions from these
facilities may vary in magnitude and control cost. Economic
studies of the source category and applicable control technology
may show that air pollution control is better served by applying
standards to the more severe pollution sources. For this reason,
and because there is no adequately demonstrated system for
controlling emissions from certain facilities, standards often do
not apply to all facilities at a source. For the same reasons,
the standards may not apply to all air pollutants emitted. Thus,
although a source category may be selected to be covered by
standards, the standards may not cover all pollutants or
facilities within that source category.
2.3 PROCEDURE FOR DEVELOPMENT OF NESHAP
Standards for major and area sources must (1) realistically
reflect MACT or GACT; (2) adequately consider the cost, the
non-air quality health and environmental impacts, and the energy
requirements of such control; (3) apply to new and existing
sources; and (4) meet these conditions for all variations of
industry operating conditions anywhere in the country.
2-6
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The objective of the NESHAP program is to develop standards
to protect the public health by requiring facilities to control
emissions to the level achievable according to the MACT or GACT
guidelines. The standard-setting process involves three
principal phases of activity: (1) gathering information,
(2) analyzing the information, and (3) developing the standards.
During the information-gathering phase, industries are
questioned through telephone surveys, letters of inquiry, and
plant visits by EPA representatives. Information is also
gathered from other sources, such as a literature search. Based
on the information acquired about the industry, EPA selects
certain plants at which emissions tests are conducted to provide
reliable data that characterize the HAP's emissions from
well-controlled existing facilities.
In the second phase of a project, the information about the
industry, the pollutants emitted, and the control options are
used in analytical studies. Hypothetical "model plants" are
defined to provide a common basis for analysis. The model plant
definitions, national pollutant emissions data, and existing
State regulations governing emissions from the source category
are then used to establish regulatory alternatives. These
regulatory alternatives may be different levels of emissions
control or different degrees of applicability or both.
The EPA conducts studies to determine the cost, economic,
environmental, and energy impacts of each regulatory alternative.
From several alternatives, EPA selects the single most plausible
regulatory alternative as the basis for the NESHAP for the source
category under study.
In the third phase of a project, the selected regulatory
alternative is translated into standards, which, in turn, are
written in the form of a Federal regulation. The Federal
regulation limits emissions to the levels indicated in the
selected regulatory alternative.
As early as is practical in each standard-setting project,
EPA representatives discuss the possibilities of a standard and
the form it might take with members of the National Air Pollution
2-7
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Control Techniques Advisory Committee, which is composed of
representatives from industry, environmental groups, and State
and local air pollution control agencies. Other interested
parties also participate in these meetings.
The information acquired in the project is summarized in the
background information document (BID). The BID, the proposed
standards, and a preamble explaining the standards are widely
circulated to the industry being considered for control,
environmental groups, other government agencies, and offices
within EPA. Through this extensive review process, the points of
view of expert reviewers are taken into consideration as changes
are made to the documentation.
A "proposal package" is assembled and sent through the
offices of EPA Assistant Administrators for concurrence before
the proposed standards are officially endorsed by the EPA
Administrator. After being approved by the EPA Administrator,,
the preamble and the proposed regulation are published in the
Federal Register.
The public is invited to participate in the standard-setting
process as part of the Federal Register announcement of the
proposed regulation. The EPA invites written comments on the
proposal and also holds a public hearing to discuss the proposed
standards with interested parties. All public comments are
summarized and incorporated into a second volume of the BID. All
information reviewed and generated in studies in support of the
standards is available to the public in a "docket" on file in
Washington, D.C. Comments from the public are evaluated, and the
standards may be altered in response to the comments.
The significant comments and EPA's position on the issues
raised are included in the preamble of a promulgation package,
which also contains the draft of the final regulation. The
regulation is then subjected to another round of internal EPA
review and refinement until it is approved by the EPA
Administrator. After the Administrator signs the regulation, it
is published as a "final rule" in the Federal Register.
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2.4 CONSIDERATION OF COSTS
The requirements and guidelines for the economic analysis of
proposed NESHAP are prescribed by Presidential Executive Order
12291 (EO 12291) and the Regulatory Flexibility Act (RFA). The
EO 12291 requires preparation of a Regulatory Impact Analysis
(RIA) for all "major" economic impacts. An economic impact is
considered to be major if it satisfies any of the following
criteria:
1. An annual effect on the economy of $100 million or more;
2. A major increase in costs or prices for consumers;
individual industries; Federal, State, or local government
agencies; or geographic regions; or
3. Significant adverse effects on competition, employment,
investment, productivity, innovation, or on the ability of United
States-based enterprises to compete with foreign-based
enterprises in domestic or export markets.
An RIA describes the potential benefits and costs of the
proposed regulation and explores alternative regulatory and
nonregulatory approaches to achieving the desired objectives. If
the analysis identifies less costly alternatives, the RIA
includes an explanation of the legal reasons why the less costly
alternatives could not be adopted. In addition to requiring an
analysis of the potential costs and benefits, EO 12291 specifies
that EPA, to the extent allowed by the CAA and court orders,
demonstrate that the benefits of the proposed standards outweigh
the costs and that the net benefits are maximized.
The RFA requires Federal agencies to give special
consideration to the impact of regulations on small businesses,
small organizations, and small governmental units. If the
proposed regulation is expected to have a significant impact on a
substantial number of small entities, a regulatory flexibility
analysis must be prepared. In preparing this analysis, EPA takes
into consideration such factors as the availability of capital
for small entities, possible closures among small entities, the
increase in production costs due to compliance, and a comparison
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of the relative compliance costs as a percent of sales for small
versus large entities.
The prime objective of the cost analysis is to identify the
incremental economic impacts associated with compliance with the
standards based on each regulatory alternative compared to
baseline. Other environmental regulatory costs may be factored
into the analysis wherever appropriate. Air pollutant emissions
may cause water pollution problems, and captured potential air
pollutants may pose a solid waste disposal problem. The total
environmental impact of an emission source must, therefore, be
analyzed and the costs determined whenever possible.
A thorough study of the profitability and price-setting
mechanisms of the industry is essential to the analysis so that
an accurate estimate of potential adverse economic impacts can be
made for proposed standards. It is also essential to know the
capital requirements for pollution control systems already placed
on plants so that the additional capital requirements
necessitated by these Federal standards can be placed in proper
perspective. Finally, it is necessary to assess the availability
of capital to provide the additional control equipment needed to
meet the standards.
2.5 CONSIDERATION OF ENVIRONMENTAL IMPACTS
Section 102(2)(C) of the National Environmental Policy Act
(NEPA) of 1969 requires Federal agencies to prepare detailed
environmental impact statements on proposals for legislation and
other major Federal actions significantly affecting the quality
of the human environment. The objective of NEPA is to build into
the decision-making process of Federal agencies a careful
consideration of all environmental aspects of proposed actions.
In a number of legal challenges to standards for various
industries, the United States Court of Appeals for the District
of Columbia Circuit has held that environmental impact statements
need not be prepared by EPA for proposed actions under the Clean
Air Act. Essentially, the Court of Appeals has determined that
the best system of emissions reduction requires the Administrator
to take into account counterproductive environmental effects of
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proposed standards as well as economic costs to the industry. On
this basis, therefore, the Courts established a narrow exemption
from NEPA for EPA determinations.
In addition to these judicial determinations, the Energy
Supply and Environmental Coordination Act of 1974 (PL-93-319)
specifically exempted proposed actions under the Clean Air Act
from NEPA requirements. According to Section 7(c)(1), "No action
taken under the Clean Air Act shall be deemed a major Federal
action significantly affecting the quality of the human
environment within the meaning of the National Environmental
Policy Act of 1969" (15 U.S.C. 793(c)(l)).
Nevertheless, EPA has concluded that preparing environmental
impact statements could have beneficial effects on certain
regulatory actions. Consequently, although not legally required
to do so by Section 102(2)(C) of NEPA, EPA has adopted a policy
requiring that environmental impact statements be prepared for
various regulatory actions, including NESHAP developed under
Section 112 of the Act. This voluntary preparation of
environmental impact statements, however, in no way legally
subjects the EPA to NEPA requirements.
To implement this policy, a separate section is included in
this document that is devoted solely to an analysis of the
potential environmental impacts associated with the proposed
standards. Both adverse and beneficial impacts in such areas as
air and water pollution, increased solid waste disposal, and
increased energy consumption are discussed.
2.6 RESIDUAL RISK STANDARDS
Section 112 of the Act provides that 8 years after MACT
standards are established (except for those standards established
2 years after enactment, which have 9 years), standards to
protect against the residual health and environmental risks
remaining must be promulgated, if necessary. The standards would
be triggered if more than one source in a category or subcategory
exceeds a maximum individual risk of cancer of 1 in 1 million.
These residual risk regulations would be based on the concept of
providing an "ample margin of safety to protect public health."
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The Administrator may also consider whether a more stringent
standard is necessary to prevent--considering costs, energy,
safety, and other relevant factors--an adverse environmental
effect. In the case of area sources controlled under GACT
standards, the Administrator is no.t required to conduct a
residual risk review.
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3. CHROMIUM ELECTROPLATING AND CHROMIC
ACID ANODIZING OPERATIONS
3.1 GENERAL
The source categories being evaluated include hard and
decorative chromium electroplating and chromic acid anodizing.
In hard plating, a relatively thick layer of chromium is
deposited directly on a base metal (usually steel) to provide a
surface with wear resistance, a low coefficient of friction,
hardness, and corrosion resistance. Hard plating is used for
items such as hydraulic cylinders and rods, industrial rolls,
zinc die castings, plastic molds, engine components, and marine
hardware. In decorative plating, the base material (e.g., brass,
steel, aluminum, or plastic) generally is plated with a layer of
nickel followed by a relatively thin layer of chromium to provide
a bright surface with wear and tarnish resistance. Decorative
plating is used for items such as automotive trim, metal
furniture, bicycles, hand tools, and plumbing fixtures. In
chromic acid anodizing, chromic acid is used to form an oxide
layer on aluminum to provide corrosion resistance. Chromic acid
anodizing is used primarily on aircraft parts and architectural
structures that are subject to high stress and corrosive
conditions. Although other types of operations performed at
metal finishing plants involve chromium in some form, the source
categories described in this document include only those
processes that use chromic acid in an electrolytic cell to
deposit chromium metal or to form an oxide film on a product.
There are an estimated 1,540 hard chromium electroplating
and 2,800 decorative chromium electroplating operations in the
United States.1 There are an estimated 680 chromic acid
3-1
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anodizing operations in the United States.2 Plating operations
range in size from small shops, with one or two small tanks that
are operated only a few hours per week, to large shops, with
several large tanks that are operated 24 hours per day, 7 days
per week. Many plating operations are captive shops that perform
chromium electroplating or chromic acid anodizing as one
operation within or for a manufacturing facility, while others
are job shops that provide custom plating or anodizing services
for many different clients. Captive and job shops may perform
hard or decorative chromium plating or chromic acid anodizing or
any combination of these three operations. Electroplating and
anodizing shops typically are located in or near industrial
centers in areas of high population density. States with large
numbers of chromium electroplaters include California, Illinois,
Massachusetts, Michigan, New York, Ohio, and Pennsylvania.
3.2 PROCESS DESCRIPTION
3.2.1 Electrochemistry
A schematic of a typical electrolytic cell is presented in
Figure 3-I.3 An electrolytic cell consists of an electrolytic
solution and an external electrical circuit. Electrolytic
solutions are composed of chemicals, dissolved in a solvent
(usually water), that are capable of conducting an electric
current by the movement of dissociated positive and negative ions
to the electrodes. The current flows toward a positively charged
electrode, or anode, and is drawn from a negatively charged
electrode, or cathode. The cathode is supplied with electrons
from an external circuit, which usually consists of a rectifier
that changes alternating current to direct current. The
positively charged ions (cations) draw electrons from the
cathode, neutralizing the positive charge; while the negatively
charged ions (anions) simultaneously release an equal number of
electrons to the anode, neutralizing their negative charge. Gain
of electrons by the cations at the cathode is called reduction,
and loss of electrons by the anions at the anode is called
oxidation. The current then flows from the anode to the cathode
3-2
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RECTIFIER
e-
I
e-
e-
e-
ANODE
A-
A«
A-
A-
A-
CATHODE
C
M++
\
C+
M++
C+
Figure 3-1. Schematic of a typical electrolytic cell
3-3
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by way of the rectifier, which acts as a pump to transfer
electrons.
In electroplating, the metal that will form the plate is
supplied to the plating solution either as a metal salt in
solution or as a soluble anode. The positively charged metal ion
is drawn to the negatively charged cathode and undergoes
reduction, resulting in the deposit of the metal on the cathode
(substrate). Water is the principal solvent used in
electroplating solutions. Depending upon the efficiency of the
electroplating process used, substantial quantities of hydrogen
and oxygen gas may be generated due to the dissociation of water
into hydrogen (H+) and hydroxyl (OH-) ions. The hydrogen ion is
drawn to the cathode where it is reduced to form hydrogen (H2)
gas. The hydroxyl ion is drawn to the anode and reacts to form
oxygen (02) and water.
3.2.2 Hard Chromium Electroplating of Metals
Hard chromium plating provides the following desirable
combination of physical and mechanical properties:
1. Low coefficient of friction;
2. High hardness factor--Vickers 800-t-;
3. Good corrosion resistance;
4. High heat resistance; and
5. Antigalling (antichafing) surface.4
Figure 3-2 presents a schematic of a typical electroplating
tank. Tanks used for hard chromium electroplating usually are
constructed of steel and lined with a polyvinyl chloride sheet or
plastisol. The anodes, which are insoluble, are made of a lead
alloy that contains either tin or antimony. The part to be
plated, the cathode, is suspended from a rack that is connected
to the cathode bar of the rectifier. The plating rack may be
loaded in the tank by hand, manually by a hoist, or by an
automatically controlled hoist system.
Plating tanks typically are equipped with some type of heat
exchanger. Before initial startup, the bath is heated to normal
plating temperatures (49° to 66°C [120° to 150°F] ) . Mechanical
agitators or compressed air supplied through pipes on the tank
3-4
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EXHAUST HOOD
HEAT
EXCHANGER
\
PLATING TANK
PUMP
ANODES
CATHODE
Figure 3-2. Basic components of chromium
electroplating equipment.
3-5
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bottom may be used to provide uniform bath temperature and
composition. Frequent cooling is required during operation
because of the heat produced by the high current load. Metal
coils and external shell-and-tube heat exchangers typically are
used to heat or cool plating solutions. Metal coils are hung on
the tank sidewall and convey either steam or coolant. In shell-
and-tube heat exchangers, plating solution is pumped from the
tank through the tube side of the heat exchanger and returned to
the tank while steam or coolant is added to the shell side of the
heat exchanger. A thermocouple is used to control the flow of
steam or coolant into the heat exchanger.
A flow diagram for a typical hard chromium plating process
is presented in Figure 3-3. The process consists of the
following steps:
1. Pretreatment (polishing, grinding, degreasing);
2. Alkaline cleaning and acid dipping (optional);
3. Chromic acid anodic treatment (optional); and
4. Chromium electroplating.
The part being plated is rinsed after each step in the process to
prevent carry-over of solution that may contaminate the baths
used in successive process steps. Either hot or cold water may
be used in rinse tanks, but hot water is more efficient than cold
water for removing contaminants. Softened, distilled, or
deionized water may be required for final rinses.
Pretreatment steps include polishing, grinding, and/or
degreasing the metal part to prepare the surface for plating.
Polishing and grinding are performed to smooth the surface of the
part. Degreasing is performed either by dipping the part in
organic solvents or by vapor degreasing the part using organic
solvents. Vapor degreasing is typically used when the surface
loading of oil or grease is excessive. The two organic solvents
most commonly used in dipping solutions or for vapor degreasing
are trichloroethylene and perchloroethylene. In vapor
degreasing, the solvent is boiled in a tank and the vapor
condenses on the part and removes the oil and grease from its
surface. Vapor degreasers must be fitted with a local
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SUBSTRATE TO BE PLATED
1
PRETREATMENT STEP
(POLISHING. GRINDING
AND DEGREASING)
ALKALINE CLEANING
RINSE
ACID DIP
RINSE
CHROMIC ACID
ANODIC TREATMENT
RINSE
ELECTROPLATING OF
CHROMIUM
CHROMIC ACID
EMISSIONS
CHROMIC ACID
EMISSIONS
RINSE
HARD CHROMIUM PLATED PRODUCT
Figure 3-3. Flow diagram for a typical hard
chromium plating process.
3-7
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ventilation system designed to pick up solvent vapors escaping
from the tanks without pulling vapor from the machine itself.
Vapor degreasers should also be installed with a safety
thermostat in the freeboard zone just above the normal vapor
level to shut off the heat as the vapor level rises above the
condensing surface (part) for any reason.5
Alkaline cleaning is sometimes used to dislodge surface soil
and prevent it from settling back onto the metal. These cleaning
solutions are typically made up of compounds such as sodium
carbonate, sodium phosphate, and sodium hydroxide and usually
contain a surfactant. Alkaline cleaning techniques include
soaking and cathodic and anodic cleaning. In soaking, the metal
is placed in an alkaline bath that is agitated mildly. In
cathodic cleaning, the metal is placed in an alkaline bath and
direct current is applied. The part acts as the cathode;
therefore, when current is applied, hydrogen gas evolves,
enhancing the detergent action of the solution. Two
disadvantages of cathodic cleaning are that impurities in the
cleaning solution may be deposited on the metal and hydrogen may
embrittle the metal. In anodic cleaning, the part is placed in
an alkaline bath and reverse current is applied. The part then
acts as the anode so that when the current is applied, oxygen gas
is evolved. One disadvantage of anodic cleaning is that oxides
may form on the surface of the metal. Also, anodic cleaning is
less efficient than cathodic cleaning because oxygen gas is
liberated at one-half the rate that hydrogen gas is liberated
during cathodic cleaning.7 During alkaline cleaning, an alkaline
mist can be released at a fairly high rate because of the
hydrogen and oxygen gases entrapping the solution and releasing
it as the bubbles burst at the surface; therefore, adequate
ventilation should be provided.8
Acid dips may be used to remove any tarnish or oxide films
formed in the alkaline cleaning step and to neutralize the
alkaline film. Acid dip solutions typically contain from 10 to
30 percent by volume hydrochloric or sulfuric acid in water.
Because of the release of hydrogen and oxygen gases, an acid mist
3-8
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is generated from the dip tanks at varying rates and, as with
alkaline cleaning, proper ventilation should be provided.8
A chromic acid anodic treatment step is sometimes included.
This treatment cleans the metal surface, with the evolution of
oxygen gas scouring the metal. The chromic acid also activates
the surface, which enhances the adhesion of chromium in the
electroplating step. A typical bath contains chromic acid in a
concentration that ranges from 120 to 240 g/L (16 to 32 oz/gal)
at temperatures ranging from 49° to 66°C (120° to 150°F).9
Satisfactory cleaning and activation of the surface are usually
obtained at 6 V and a current density ranging from 1,550 to
4,650 A/m2 (140 to 430 A/ft2) for 1 to 3 minutes.10 Anodic
treatment is typically accomplished by applying reverse current
in the hard chromium plating tank.11 The anodic treatment also
adds a protective oxide layer to the metal so that the chromium
can be plated without applying an undercoating of nickel.
The final step of the process is the chromium electroplating
operation. Chromium electroplating requires constant control of
the plating bath temperature, current density, plating time, and
bath composition. Typical operating parameters are given in
Table 3-I.12
TABLE 3-1. TYPICAL OPERATING PARAMETERS
FOR HARD CHROMIUM ELECTROPLATING
Plating thickness, urn (mil) 1.3-762 (0.05-30)
Plating time, min 20-2,160
Chromic acid concentration, g/L (oz/gal) 225-375 (30-50)
Sulfuric acid concentration, g/L (oz/gal) 2.25-3.75 (0.3-0.5)
Temperature of solution, °C (°F) 49-66 (120-150)
Voltage, V a
Current, A b
Current density, A/m2 (A/ft2) 1,600-6,500 (150-600)
aDepends on the distance between the anodes and the items being plated.
"Depends on the amount of surface area plated.
3-9
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Chromic acid plating baths are most widely used for
depositing chromium on metal. Chromium anhydride (Cr03) is the
hexavalent compound of chromium used to make up the plating bath.
By common usage, Cr03 is widely known as chromic acid.
Therefore, in this document Cr03 will be referred to as chromic
acid. The baths typically contain chromic acid in a
concentration of 225 to 375 g/L (30 to 50 oz/gal of water). In
addition, small amounts of sulfuric acid (2.25 to 3.75 g/L [0.3
to 0.5 oz/gal]) are added as a bath catalyst. As Cr03 is added
to water, it reacts with the water to form a compound (H2Cr04),
which is correctly called chromic acid. As more Cr03 is added to
the plating bath, the H2Cr04 molecules combine to form dichromic
acid (H2Cr207) and water. As dichromic acid forms, it readily
ionizes to form dichromate ions (Cr207=) and hydrogen ions (H+).
The dichromate ions are then used in the chromium deposition
reaction as discussed below.
The cathode reactions take place at the surface of the part
to be plated. These are the deposition reaction and two side
reactions:13
1. Cr207= + 14H+ + 12 (e) -» 2Cr° + 7H20
2. 2H+ + 2 (e) •* H2t
3. Cr207= + 14H+ + 6(e) •* 2Cr+3 + 7H20
The first reaction deposits the chromium metal on the part to be
plated. In this reaction, the dichromate ion reacts with
hydrogen ions and electrons to form chromium metal and water.
This reaction takes place in the presence of a catalyst, the
sulfate ion. In addition to this deposition reaction, two side
reactions also take place. In the first side reaction, two
hydrogen ions combine with two electrons to form hydrogen gas.
The evolution of hydrogen gas consumes 80 to 90 percent of the
power supplied to the bath, leaving the remaining 10 to
20 percent for the deposition reaction. When the hydrogen gas
evolves, it entrains chromic acid and causes misting at the
surface of the plating bath. In the second side reaction, the
dichromate ion combines with hydrogen ions and electrons to form
water and trivalent chromium, which is detrimental to the bath.
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The trivalent chromium is reoxidized to chromic acid at the
anode. The anode area is always larger than the cathode area to
ensure that most of the trivalent chromium formed at the cathode
will react at the anode to form chromic acid. This technique
does not always ensure, however,- that the concentration of
trivalent chromium will not build up to a level that will
contaminate the bath.
The preferred anode material for chromium electroplating is
lead alloyed with tin or antimony. The following reactions take
place at the anode during chromium electroplating:14
1. 40H" - 4(e) -» 2H20 + 02t
2. Pb + 40H" - 4(e) -* Pb02 + 2H20
3. 2Cr*3 + 302t - 6(e) -* 2Cr03
Most of the energy from the electric current is consumed in the
first reaction. The second reaction (lead and hydroxyl ions)
allows the third reaction to take place due to the coating of
lead peroxide. The third reaction (trivalent chromium with
oxygen) reoxidizes trivalent chromium to chromic acid. This
reaction purifies the bath by keeping the number of trivalent
chromium ions low.
3.2.3 Decorative Chromium Electroplating of Metals
The purpose of decorative chromium plating is to achieve a
unique combination of surface properties. Decorative chromium
plate is characterized by a blue-white color. It has a high
reflectivity that endures long use because of the excellent
tarnish resistance of chromium. It is highly resistant to
corrosion and exhibits good wear and scratch resistance.15
The decorative chromium plating process consists of a series
of plating operations. Figure 3-4 presents a process flow
diagram for the decorative chromium plating of metals (i.e.,
brass, steel, and aluminum). The process consists of the
following steps:
1. Pretreatment (polishing, grinding, degreasing);
2. Alkaline cleaning;
3. Acid dipping;
4. Strike plating of copper;
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METAL SUBSTRATE TO BE PLATED
P R E T R E AT WENT STEP
(POLISHING. GRINDING.
AND DECREASING)
ALKALINE CLEANING
RINSE
ACID DIP
RINSE
STRIKE PLATING OF
COPPER
RINSE
ACID DIP
RINSE
ELECTROPLATING OF
COPPER
RINSE
ELECTROPLATING OF
SEMIBRIGHT NICKEL
RINSE
ELECTROPLATING OF
BRIGHT NICKEL
RINSE
ELECTROPLATING OF
CHROMIUM
CHROMIC ACID
EMISSIONS
DECORATIVE CHROMIUM PLATED PRODUCT
Figure 3-4. Flow diagram for decorative chromium
plating on a metal substrate.
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5. Electroplating of copper;
6. Electroplating of nickel; and
7. Electroplating of chromium.
As with hard chromium plating, the part being plated is rinsed
after each step in the process to prevent carry-over of solution
that may contaminate the baths used in successive process steps.
Either hot or cold water may be used in the rinse tanks, but hot
water is more efficient than cold water for removing
contaminants. Softened, distilled, or deionized water may be
required for final rinses.
Decorative electroplating baths operate on the same
principle as that described for the hard chromium plating
process: The part to be plated is immersed in a plating
solution, and direct current is passed from the anode through the
plating solution causing the desired metal (copper, nickel,
chromium) to deposit out of the solution onto the surface of the
part to be plated (cathode).
Pretreatment steps include polishing, grinding, and/or
degreasing the part to prepare for plating. Polishing and
grinding are performed to smooth the surface of the part.
Alkaline cleaning may be used to dislodge surface soil and
prevent it from settling back onto the metal. Acid dipping is
sometimes used to remove tarnish or oxide films formed in the
alkaline cleaning step. Acid dips are also typically used
following strike plating of copper. These steps are described in
more detail in Section 3.2.2 for hard chromium plating.
The first step following pretreatment is a copper strike,
which consists of applying a thin layer of copper to enhance the
conductive properties of the base metal and to protect the part
from attack by the acidic copper sulfate baths. The plating bath
is typically a copper cyanide solution.16 The plating time (0.5
to 2.0 min) is limited to that necessary for complete coverage of
a thin layer (2.5 /xm [0.1 mil]) over the entire surface of the
part.17 Strike plating of copper typically is followed by an
acid dip.
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The part is then usually electroplated with an undercoat of
copper to improve the corrosion resistance and to cover scratch
marks and other defects. Copper deposits in the recesses of the
part more readily than nickel or chromium, and this enhances the
corrosion resistance of the part.1® The baths used for copper
electroplating are either alkaline (cyanides or pyrophosphates)
or acid copper solutions. Copper cyanide solution is used most
often; however, use of an acid copper bath is growing, due mainly
to the low chemical cost and simplified effluent treatment.19
The acid copper bath requires a copper strike plate for steel
substrates before electroplating because the copper cannot be
applied directly to steel; however, copper cyanide baths can be
directly applied to the steel substrate.20 Copper cyanide baths
are composed of copper cyanide, potassium or sodium cyanide,
potassium or sodium hydroxide, potassium or sodium carbonate, and
a Rochelle salt. Acid copper baths are usually composed of
copper sulfate, sulfuric acid, chloride, and thiourea. Another
commonly used acid plating formulation contains copper fluoborate
(instead of copper sulfate} as the active component. Table 3-2
presents the operating parameters for typical copper plating
baths.21'22 Copper may be deposited as a matte finish, or
brightening agents may be added to the bath to produce a
semibright or bright surface.
TABLE 3-2. TYPICAL OPERATING PARAMETERS FOR COPPER PLATING BATHS
Copper cyanide
Acid copper
Plating bath temperature, °C (°F)
Current density, A/m2 (A/ft2)
Plating time, min
Cathode efficiency, percent
24-66 (75-140)
54-430 (5-40)
3-5
30-99
24-32 (75-90)
215-860 (20-80)
4-5
95-100
When a cyanide bath is used for strike copper plating or
copper electroplating, both cyanide and alkaline mist are
released from the bath. The potential for release of significant
3-14
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concentrations of these materials into the workroom atmosphere is
great enough to warrant the use of local exhaust ventilation.23
Acid copper plating solutions are capable of releasing the copper
salt and sulfuric acid mist into the atmosphere, but because of
the generally high electrode efficiencies, acid mist generation
is minimal. However, when high current densities or agitation is
used, mist generation can increase and local exhaust ventilation
must be provided.24
Nickel plating improves the corrosion resistance and
strength of the metal substrate and activates the surface of the
metal for chromium plating. The nickel is plated on the surface
of the part in two layers. The first layer is semibright
(sulfur-free) nickel, and the second layer is bright (sulfur-
containing) nickel. Pits that form in the outer (bright) layer
cannot continue through the inner (semibright) layer because of
the difference in the electromagnetic properties of the two
layers.25 Semibright nickel and bright nickel baths are both
variations of the Watts bath, and the constituents are nickel
sulfate (or nickel sulfamate), nickel chloride, and boric acid.
The semibright nickel additives are coumarin or other proprietary
materials that act as leveling agents to hide surface defects, a
brightener, and a wetting agent. The bright nickel bath is a
high-chloride version of the Watts bath, which also contains a
brightener and a wetting agent. Nickel plating baths typically
operate at 45° to 65°C (110° to 150°F) with current densities
ranging from 270 to 1,075 A/m2 (25 to 100 A/ft2).26
Generally, gassing from the nickel plating solutions
containing sulfate and/or chloride baths is low because the baths
are operated at moderate temperatures and low to moderate current
densities and have high cathode efficiencies (95 to 98 percent).
The need for local exhaust ventilation under such conditions may
be minimal.27
The final step in the decorative chromium plating process is
the plating of chromium itself. Typical operating parameters for
this step are presented in Table 3-3.2^ As can be seen when
comparing these parameters with those for hard chromium plating
3-15
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(Table 3-1), decorative chromium deposits are considerably
thinner than those associated with the functional hard chromium
plating process. The current densities required for decorative
chromium plating are about one-third lower than those required
for hard chromium plating, and, therefore, the operating
temperatures are lower for the decorative process. Plating times
required for decorative chromium plating are much shorter than
the times required for hard chromium plating.
TABLE 3-3. TYPICAL OPERATING PARAMETERS FOR
DECORATIVE CHROMIUM PLATING
Plating thickness, /im (mil) 0.003-2.5 (0.0001-0.1)
Plating time, min 0.5-5
Chromic acid concentration, g/L (oz/gal) 225-375 (30-50)
Sulfuric acid concentration, g/L (oz/gal) 2.25-3.75 (0.3-0.5)
Temperature of solution, °C (°F) 38-46 (100-115)
Voltage, V a
Current, A b
Current density, A/m2 (A/ft2) 540-2,400 (50-220)
aDepends on the distance between the anodes and the items being plated.
bDepends on the amount of surface area being plated.
Each of the operating parameters must be carefully monitored
during the plating process. The chemistry of the bath affects
plating speed, covering power, and operating voltage
requirements. The plating speed is the rate of film growth and
is typically expressed in microinches per minute. Covering power
is the ability of a plating solution to produce a deposit at very
low current densities. The bath temperature has an effect on
plating speed and current density. Current density also affects
plating speed as well as the covering power and plating
thickness.
The composition of the plating bath and the deposition
reactions for decorative chromium electroplating are the same as
3-16
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those described for hard chromium plating. Some decorative
chromium plating operations use fluoride catalysts instead of
sulfuric acid because fluoride catalysts, such as fluosilicate or
fluoborate, have been found to produce higher bath
efficiencies.2^
3.2.4 Decorative Chromium Electroplating of Plastics
Most plastics that are electroplated with chromium are
formed from the polymer composed of acrylonitrile, butadiene, and
styrene (ABS).30 The process for chromium electroplating of ABS
plastics consists of the following steps:
1. Chromic acid/sulfuric acid etch;
2. Dilute hydrochloric acid dip;
3. Collodial palladium activation;
4. Dilute hydrochloric acid dip;
5. Electroless nickel plating or copper plating; and
6. Chromium electroplating.
After each process step, the plastic is rinsed with water to
prevent carry-over of solution from one bath to another. The
chromic acid/sulfuric acid etch solution (see Table 3-4) renders
the ABS surface hydrophilic and modifies the surface to provide
adhesion for the metal coating.31 The dilute hydrochloric acid
dips are used to clean the surface and remove palladium metal
from the plating rack, which is insulated with a coating of
polyvinyl chloride. The colloidal palladium activation solution
(see Table 3-5) deposits a thin layer of metallic palladium over
the plastic surface.32 The metallic palladium induces the
deposition of copper or nickel, which will not deposit directly
onto plastic. Electroless nickel or copper plate is applied to
impart electrical conductivity to the part; otherwise, the
insulating surface of the plastic could not be electroplated with
chromium. The electroless nickel plating or copper electro-
plating baths develop a film on the plastic about 1.0 /*m
(0.039 mil) thick. The plating time for electroless nickel
plating and electroless copper plating ranges from 10 to
15 minutes and 15 to 30 minutes, respectively, at temperatures
ranging from 25° to 35°C (77° to 95°F). The components of the
3-17
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plating baths include the metal salt (nickel or copper), a
reducing agent, a complexing agent, a stabilizer, and a pH buffer
system.3-* The decorative chromium electroplating cycle is the
same as that described above in Section 3.2.3.
TABLE 3-4. CHROMIC ACID/SULFURIC ACID ETCH SOLUTION
Concentrated sulfuric acid, g/L (oz/gal) 172 (23)
Chromic acid, g/L (oz/gal) 430 (57)
Temperature, °C (°F) 60-65 (140-149)
Immersion time, min 3-10
TABLE 3-5. COLLOIDAL PALLADIUM ACTIVATING SOLUTION
Palladium chloride, g/L (oz/gal) 0.007 (9.0 x 10"4)
Stannous chloride, g/L (oz/gal) 35.0 (4.7)
Stannic chloride, g/L (oz/gal) 4.0 (0.53)
Concentrated hydrochloric acid, g/L (oz/gal) 480 (64)
Temperature, °C (°F) 25-30 (77-86)
Immersion time, min 3-6
3.2.5 Chromic Acid Anodizing of Aluminum
Anodizing is the process of forming a film of surface oxide
electrolytically. Used primarily for aluminum and its alloys,
anodizing improves resistance to corrosion, provides electrical
insulation, and enhances the ease of coloring. There are several
types of anodizing, of which sulfuric acid processes are the most
commercially important. However, where parts may be subjected to
considerable stress (e.g., aircraft parts), the potential
retention of corrosive sulfuric acid in crevices and recesses of
anodized parts could cause problems. Chromic acid, on the other
hand, is a recognized corrosion inhibitor, so its retention in
crevices and joints does not present a problem. This makes
chromic acid the preferred (and specified) anodizing process for
3-18
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aircraft parts, as well as for other assemblies with overlapping
joints, recesses, or crevices. Another advantage of chromic acid
anodic coatings is their very high resistance to salt spray
corrosion as compared to sulfuric acid coatings of the same
thickness.34
There are four primary differences between the equipment
used for chromic acid anodizing and that used for chromium
electroplating: (l) rectifiers must be fitted with a rheostat or
other control mechanism to permit voltage adjustments; (2) the
tank rather than the part is the cathode in the electrical
circuit; (3) the part acts as the anode; and (4) sidewall shields
are used instead of a tank liner to minimize short circuits and
to decrease the effective cathode area.35
Figure 3-5 presents a flow diagram for a typical chromic
acid anodizing process. The process consists of pretreatment
operations, the actual chromic acid anodizing step, and
postanodizing operations that include sealing and air-drying.
The following pretreatment steps are typically used to clean
the aluminum before anodizing:
1. Alkaline soak;
2. Etching;
3. Desmutting; and
4. Vapor degreasing.
The pretreatment steps used for a particular aluminum substrate
depend upon the amount of smut and the composition of the
aluminum. The aluminum substrate is rinsed between pretreatment
steps to remove cleaners. The use of water rinsing following
cleaning and all subsequent treatments is critical, and the use
of rinse tanks common to all process steps is avoided.
The alkaline soak is the primary preparatory step in
cleaning the aluminum; its purpose is to dislodge soil from the
aluminum surface. The solutions for alkaline cleaning are
typically made up of compounds such as sodium carbonate, sodium
phosphate, and sodium hydroxide and usually contain a small
amount of silicate to prevent metal attack.3^ The alkaline soak
3-19
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SUBSTRATE TO BE PLATED
1
PRETREATMENT STEPS
RINSE
CHROMIC ACID ANODIZING
RINSE
SEALING
CHROMIC ACID
EMISSIONS
CHROMIC ACID ANODIZED PRODUCT
Figure 3-5. Flow diagram for a typical chromic
acid anodizing process.
3-20
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step consists of immersing the metal in the alkaline solution,
which is mildly agitated with air.
When a dull finish is desired, the aluminum is etched before
anodizing. Etching baths consist of dilute solutions of soda
ash, caustic soda, or nitric acid.37 When soda ash or caustic
soda is used, aluminum parts are rinsed with water, dipped in
concentrated nitric acid for a few seconds, and rinsed with water
again. The degree of etching desired and the composition of the
aluminum being treated determine the concentration of the etch
solution, temperature of the bath, and duration of the etch.
Another pretreatment step is desmutting, which removes soil
or grease films that cleaners and etchants leave behind.
Desmutting baths typically consist of a cold nitric acid solution
mixed with water at a concentration ranging from 5 to 50 percent
acid by volume. The nitric acid bath is also used either as a
bleaching treatment to remove dyes from faulty coatings or as
part of the technique of producing multicolor coatings.38 Other
desmutting treatments use combinations of chromic, phosphoric,
and sulfuric acids depending upon the amount of smut to be
removed or the aluminum composition of the part.
Vapor degreasing typically is used when the surface loading
of oil or grease is excessive. The two organic solvents most
commonly used in dipping solutions or for vapor degreasing are
trichloroethylene and perchloroethylene. In vapor degreasing,
the solvent is boiled in a tank, and the vapor condenses on the
part and removes the oil and grease from the surface of the part.
The next step in the process is the actual anodizing.
Typical operating parameters for chromic acid anodizing baths are
presented in Table 3-6.39'40 The voltage is applied step-wise
(5 V per minute) from 0 to 20 or 40 V and maintained at the
desired voltage for the remainder of the anodizing time.41 The
total anodizing time is typically 30 to 60 minutes. A low
starting voltage (e.g., 5 V) minimizes current surge that may
cause "burning" at contact points between supporting racks and
aluminum parts being anodized. The process is effective over a
wide range of voltages, temperatures, and anodizing times. In
3-21
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general, high voltages tend to produce bright transparent films,
and lower voltages tend to produce opaque films.42 Raising the
bath temperature increases current density to produce thicker
films in a given time period. Temperatures up to 49°C (120°F)
typically are used to produce films that are to be colored by
dyeing.43 The amount of current applied varies depending on the
size of the aluminum part(s). Typical current densities range
from 1,550 to 7,750 A/m2 (144 to 720 A/ft2).
TABLE 3-6. TYPICAL OPERATING PARAMETERS FOR
CHROMIC ACID ANODIZING
Chromic acid concentration, g/L (oz/gal) 50-100 (6.67-13.3)
Temperature, °C (°F) 32-35 (90-95)
Anodizing time, min 30-60
pH 0.5-0.85
Current density, A/m2 (A/ft2) 1,550-7,750 (144-720)
Voltage (step-wise), V 20 or 40
Film thickness, fim (mil) 0.15-1.27 (0.02-0.05)
When the current is applied, chromic acid breaks down in the
bath resulting in the liberation of oxygen and hydrogen. The
oxygen is evolved at the surface of the aluminum part where it
reacts with the substrate to form an aluminum oxide layer. At
the same time, chromic and dichromic acids contained in the bath
react with the aluminum oxide film in a dissolving action.44
This action results in the formation of very fine pores,
enhancing the continuation of current flow to the metal surface.
Competition between the oxide film growth and oxide dissolution
regulates the anodic film properties. As the film thickens, the
growth rate decreases until it is equal to the oxide dissolution
rate, at which point the film thickness reaches a limiting value
dependent on the current density. This process usually takes 30
to 40 minutes. About half of the oxidized aluminum is retained
as anodic film, and the remainder goes into solution to form
3-22
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alumina-chromic acid compounds.4 The relationship between the
cathode and the shape or relative location of the anode is not
critical in chromic acid anodizing.46
After the anodizing is complete, the anodized parts undergo
several postanodizing steps. These include sealing and air
drying. Sealing causes hydration of the aluminum oxide and fills
the pores in the aluminum surface. As a result, the elasticity
of the oxide film increases but the hardness and wear resistance
decrease.47 Sealing is performed by immersing aluminum in a
water bath at 88° to 99°C (190° to 210°F) for a minimum of
15 minutes.48 Chromic acid or other chromates may be added to
the solution to help improve corrosion resistance. The aluminum
is allowed to air dry after it is sealed.
3.2.6 Other Plating and Metal Treatment Processes Involving
Chromium
3.2.6.1 Trivalent Chromium Plating. Trivalent chromium
electroplating baths were developed primarily as an alternative
to hexavalent chromium plating baths for decorative chromium
plating. Development of a trivalent chromium plating process has
been difficult due to the tendency of trivalent chromium to
solvate in water to form complex stable ions that do not release
chromium readily. State-of-the-art trivalent chromium baths that
have been developed are complex in chemistry and are generally
considered proprietary by suppliers.
The first trivalent chromium plating bath was developed in
the mid-1800's, but the process did not become commercially
successful until 1975. There are two types of trivalent chromium
processes available for decorative chromium plating: the single-
cell and the double-cell. In the single-cell process, anodes are
in direct contact with the plating solution. In the double-cell
process, anodes are encased in boxes that are lined with a
permeable (ion-selective) membrane and that contain a dilute
solution of sulfuric acid. This membrane allows the passage of
hydrogen ions but not other positively charged ions (such as the
trivalent chromium species present in the plating solution).
This mechanism prevents undesirable side reactions (such as
3-23
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oxidation of trivalent chromium to hexavalent chromium) from
occurring at the anode. The use of a weak solution of sulfuric
acid, contained within the box, facilitates hydrogen ion
transport through the membrane (away from the anode) to
compensate for hydrogen gas evolution at the cathode.4^
The advantages of the trivalent chromium processes over the
hexavalent chromium process are (l) fewer environmental
concerns, (2) higher productivity, and (3) lower operating costs.
In the trivalent chromium process, chromic acid is not present in
the plating solution. Furthermore, hexavalent chromium is
regarded as a plating bath contaminant in this process.
Trivalent chromium is much less toxic than hexavalent chromium
and is not presently listed as a potential human carcinogen, as
is hexavalent chromium. The total chromium concentration in
trivalent chromium solutions is approximately one-fifth that in
hexavalent chromium solutions.^ As a result of the trivalent
chromium bath chemistry, the surface tension of the plating
solution is approximately 40 dynes/cm (2.7 x 10"^ Ib^/ft). At
this low surface tension, any hydrogen gas that is evolved at the
cathode will not burst at the surface of the solution to produce
a chromium mist. Based on visual observation made during site
visits to trivalent chromium plating facilities, no detectable
misting is observed at the surface of the solution, and because
of this most plants do not ventilate the plating tank.. Use of
trivalent chromium also reduces waste disposal problems and the
associated costs. Waste treatment of hexavalent chromium is a
two-stage process. The hexavalent chromium is first reduced to
the trivalent chromium ion; then it can be precipitated as
chromium hydroxide. Trivalent chromium plating solution
wastewaters are already in the reduced trivalent state and
require only the chromium hydroxide-precipitation step.
An advantage of the trivalent chromium process is that it
has better covering and throwing power than the hexavalent
chromium process. Throwing power is the ability to form
electrodeposited films of such uniform thickness that even the
most recessed areas of a part are covered. Better throwing and
3-24
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covering power results in increased productivity because less
stripping and replating of parts is required, more parts can be
placed on a rack, and more racks can be placed on a workbar.51
Chromium color buffing is also eliminated when using most
trivalent chromium processes. The gray "burnt" areas caused by
the high current densities used in the hexavalent chromium
process must be buffed to restore the bright and shiny appearance
of the plated surface. Because the trivalent chromium processes
use cathode current densities that are about half those used for
the hexavalent process, burning does not occur.
Two disadvantages of the trivalent chromium process, as
compared with the hexavalent chromium process, are that the
trivalent chromium process is more sensitive to contamination,
and it cannot plate the full range of plate thicknesses.52
Because it is sensitive to contamination, the trivalent chromium
process requires more thorough rinsing and tighter laboratory
control (more frequent analyses of bath composition). Trivalent
chromium baths can plate thicknesses ranging from 0.13 to 25 /*m
(0.005 to 1.0 mils) thick.53 The hexavalent chromium process is
able to plate up to 762 pm (30 mils) thick. Therefore, trivalent
chromium solutions cannot be used for most hard chromium plating
applications.
Special precautions must be taken when the trivalent
chromium process is used with brass, zinc, and tubular (hollow)
steel parts. The copper, zinc, and lead metals found in these
parts can contaminate the trivalent chromium solution if the
parts fall off the racks and the metals dissolve in the solution
or if there is insufficient coverage in the nickel bath and the
base metals are exposed and dissolve in the solution. Tubular
(hollow) brass or steel parts present unique problems because the
throwing power in the nickel plating process is not sufficient to
cover the internal surfaces of tubular parts. This can result in
lead or copper contamination of the trivalent chromium
solution.54
The plating efficiency of a trivalent chromium bath,
approximately 20 to 25 percent, is slightly higher than that of a
3-25
-------
hexavalent chromium plating bath.55 The color, hardness, and
corrosion resistance of trivalent chromium deposits are
comparable to those of hexavalent chromium deposits.56 However,
the composition of the trivalent chromium deposit is
significantly different from that of the hexavalent chromium
deposit as shown in Table 3-7.57
TABLE 3-7. HEXAVALENT AND TRIVALENT CHROMIUM
DEPOSIT COMPOSITIONS
Chromium
deposit
Hexavalent
Trivalent
Carbon,
percent wt
0.0
2.9
Oxygen,
percent wt
0.4
1.6
Chromium,
percent wt
99 +
95 +
3.2.6.2 Chromating. Chromating refers to the application
of chromate conversion coatings on metals. The coatings are
produced by chemical or electrochemical treatment involving
mixtures of hexavalent chromium and certain other compounds.
Film formation requires the presence of certain anions
(activators). These include acetate, formate, sulfate, chloride,
fluoride, nitrate, phosphate, and sulfamate ions. Chromate film
properties and rate of formation are dependent on the particular
activator and its concentration. Therefore, many formulations
have been developed on a proprietary basis. The concentration of
hexavalent chromium can vary widely. One important factor in
controlling the formation of the film is the pH of the treatment
solution. The optimum pH value varies with different
metal/chromate systems. The rates of metal dissolution and metal
formation are determined by the pH of the solution.58
Chromating is usually done by immersion, although spraying,
brushing, swabbing, or electrolytic methods may be used.59 The
chromating process involves oxidation of the metal surface in the
chromating solution with simultaneous transition of the basis
metal ions to the solution and evolution of hydrogen. The
3-26
-------
liberated hydrogen reduces a certain amount of hexavalent
CQ
chromium to trivalent chromium. y The solution then contains a
complex mixture of chromates and oxides of both chromium and the
basis metal. Therefore, the film consists of indefinite
proportions of materials involved in the process. The properties
of chromate coatings depend upon the chemical makeup, pH, and
temperature of the chromating solution and the contact time of
the solution and metal, which can vary from 1 second to 1 hour.58
3.3 UNCONTROLLED EMISSIONS
Plating operations generate mists due to the evolution of
hydrogen and oxygen gas. The gases are formed in the process
tanks on the surface of the submerged part or on anodes or
cathodes. As these gas bubbles rise to the surface, they escape
into the air and may carry considerable liquid with them in the
form of a fine mist. The rate of gassing is a function of the
chemical or electrochemical activity in the tank and increases
with the amount of work in the tank, the strength and temperature
of the solution, and the current densities in plating tanks. °
Emissions are also generated from surface preparation steps
(alkaline cleaning, acid dipping, and vapor degreasing). These
emissions are in the form of alkaline and acid mists and solvent
vapors. (Solvent [volatile organic compounds] emissions from
vapor degreasing operations are currently the subject of a
regulation being developed by EPA.)
The extent of acid misting from the plating processes
(copper, nickel, and chromium) depends mainly on the efficiency
of the plating bath. Both copper and nickel plating baths have
high cathode efficiencies so that the generation of mist is
minimal. However, the cathode efficiency of chromium plating
baths is very low (10 to 20 percent), and a substantial quantity
of chromic acid mist is generated.
The focus of this study is on chromic acid emissions from
chromium plating baths because of the adverse health affects of
hexavalent chromium and the significant quantity of chromium
emitted. The other plating processes discussed above are not
significant emitters of toxic pollutants, or they are common to
3-27
-------
numerous metal finishing operations other than chromium
electroplating processes.
Emissions of chromic acid mist from the electrodeposition of
chromium in chromic acid plating baths occur because of the
inefficiency of the hexavalent chromium plating process; only
about 10 to 20 percent of the current applied actually is used to
deposit chromium on the item plated. Eighty to 90 percent of the
current applied is consumed by the evolution of hydrogen gas at
the cathode with the resultant liberation of gas bubbles.
Additional bubbles are formed at the anode due to the evolution
of oxygen. As the bubbles burst at the surface of the plating
solution, a substantial amount of fine chromic acid mist is
formed.
3.3.1 Hard and Decorative Chromium Plating Operations
A source test program was established to quantify
uncontrolled hexavalent chromium emissions from hard and
decorative chromium electroplating operations. The following
sections present a description of the facilities tested, the
source test method and procedures used to quantify uncontrolled
emissions, the uncontrolled hexavalent chromium emissions data,
factors affecting the uncontrolled emissions, and the development
of process emission factors.
3.3.1.1 Facility Descriptions. Facilities selected for
emissions testing were representative of typical hard and
decorative chromium plating shops based on the size of the
plating tanks, the types of parts plated, and the plating bath
operating parameters. The operating parameters examined at each
facility were the current, voltage, plating time, temperature,
and chromic acid concentration of the plating bath. Nine hard
chromium plating operations and two decorative chromium plating
operations were selected for emissions testing. Tables 3-8 and
3-9 present the key operating parameters monitored during the
emissions tests. Voltages, chromic acid concentrations, and
temperatures did not vary significantly among the hard or the
decorative chromium plating operations tested. These monitored
parameters are representative of typical operating values for
3-28
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3-29
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conventional hard and decorative chromium plating baths.
However, the amount of current supplied to the plating baths
during the emissions tests varied considerably among facilities
because of differences in the sizes and quantities of parts
plated and the thicknesses of chromium applied. The types of
parts that were plated at the hard chromium plating facilities
during testing were typical hard chromium plated parts such as
industrial rolls, hydraulic cylinders, and crankshafts. The
types of parts (automotive) that were plated at the decorative
chromium plating facilities during testing were representative of
typical parts that are decorative chromium plated. Appendix C
presents a more detailed description of the facilities tested.
3.3.1.2 Source Test Method. Mass emission sampling was
conducted using an isokinetic sampling train. A minimum of three
mass emission test runs were conducted at each test facility.
Each test run was typically 2 to 3 hours in duration. The sample
location at each facility was downstream of the hood in an area
of the duct preceding any air pollution control device and where
flow disturbances were minimal or nonexistent. Prior to
sampling, velocity, static pressure, molecular weight, moisture
content, and temperature of the gas stream were measured to
determine the sampling rate and nozzle size. The duct area is
sampled by traversing across two perpendicular diameters. The
number of traverse points or sampling points along one diameter
is determined based on the size of the duct. Traversing of the
duct is necessary because the distribution of chromium in the
duct is not uniform. Following sample collection and recovery,
the hexavalent chromium content of the sample was determined by
spectrophotometry. For a more detailed discussion of the test
methods and subsequent analyses, refer to Appendix D.
3.3.1.3 Uncontrolled Emission Data. Tables 3-10 and 3-11
present the uncontrolled hexavalent chromium emissions data
collected at each of the hard and decorative chromium plating
operations tested. As shown in Table 3-10, the average
uncontrolled hexavalent chromium emission concentration at the
hard chromium plating operations ranged from 697 x 10~3 to
3-30
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11,400 x 10"3 mg/dscm (3.05 x 10"4 to 4.98 x 10'3 gr/dscf), and
the hexavalent chromium mass emission rate varied from 0.015 to
0.090 kg/hr (0.033 to 0.199 Ib/hr). The range of mass emission
rates for the hard chromium plating operations is narrower than
the range in the concentration data, this is because the mass
emission rate is normalized based on the varying ventilation
rates at each facility. As shown in Table 3-11, the average
uncontrolled hexavalent chromium emission concentration at
decorative chromium plating operations varied from 916 x 10"3 to
1,600 x 10"3 mg/dscm (4.0 x 10"4 to 6.99 x 10"4 gr/dscf), and the
hexavalent chromium mass emission rate varied from 0.004 to
0.066 kg/hr (0.008 to 0.145 Ib/hr).
3.3.1.4 Factors Affecting Emissions. Numerous factors'
cause the variability in the emission data. These factors
include:
1. Current density applied;
2. Surface area of the part plated;
3. Plate thickness; and
4. Plating time.
These factors are all interrelated and are determined by
using the electrochemical equivalent of chromium, which is:
(Current, amperes) (Plating time, hr) C1 Q
' — D -L • O
(Thickness, mil) (Surface area of part, ft2)
The electrochemical equivalent is derived from Faraday's
law. The equation above is based on a cathode efficiency of
100 percent and means that 51.8 Ah are required to deposit 25 /*m
(l mil) of chromium per square foot of part surface area. As
discussed previously, the cathode efficiency for actual chromium
plating baths is only 10 to 20 percent. The known variables in
the equation above for all platers are the surface area of the
part and the minimum plate thickness. The unknowns are then
calculated by modifying the equation to account for the actual
cathode efficiency. In the majority of cases, the plating time
is the factor that is adjusted to account for the lower cathode
efficiency. It is a common practice to set the current based on
3-33
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a current density of 3,100 A/m2 (2 A/in.2) for hard chromium
plating and approximately 1,500 A/m2 (l A/in.2) for decorative
chromium plating. The low cathode efficiency means that 80 to
90 percent of the current supplied to the bath goes to form
hydrogen gas, which entraps the chromium solution. The amount of
misting then becomes directly proportional to the amount of
current supplied over a given time period.
Other factors that affect the amount of emissions are:
1. Type of parts plated;
2. The orientation of the parts within the tank;
3. The chromic acid concentration; and
4. The surface tension of the plating bath.
The type of part plated affects emissions because of its shape.
For example, if two similar parts (parts with the same surface
area plated) are plated to equal minimum thicknesses, but one
part has a smooth surface and the other part has many recessed
areas, the part with the recessed areas will require more current
than the part with the smooth surface. The poor throwing power
of chromium plating baths results in thicker deposits in the high
current density range and thinner deposits in the low current
density range. The current densities vary across the surface of
recessed parts because of the varying distances from the anode.
The orientation of the part within the tank also affects the
amount of emissions. For example, if the same part is plated in
a shallow horizontal tank, more chromium will be emitted than if
the part is plated in a deep vertical tank. In a shallow tank,
the hydrogen gas is evolved closer to the surface of the solution
and the agitation effect is much greater than with the hydrogen
gas generated in a deeper tank. The chromic acid concentration
affects emissions generation because the higher the concentration
of the solution that is entrapped in the hydrogen gas bubbles,
the more chromium will be emitted when the bubbles burst to form
the mist. The surface tension of the plating solution is another
factor that affects the emissions. Common hexavalent chromium
plating baths have a surface tension of 70 dynes/cm
(4.8 x 10"3 Ibj/ft). However, surfactants can be added to the
3-34
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plating bath to reduce the surface tension below 40 dynes/cm
(2.7 x 10"3 lbf/ft). At the lower surface tension, the hydrogen
gas bubbles will not burst at the surface of the solution and the
misting is substantially reduced. It should be noted that the
facilities tested did not use surfactants during the tests
because of the need to measure actual uncontrolled emissions.
However, the ability of wetting agents to reduce uncontrolled
emissions was determined and is discussed in Chapter 4.
There are two other factors that do not affect the quantity
of emissions generated but that do affect the measurement of
those emissions. These factors are the ventilation rate and the
sample location in the duct. The ventilation rate must be
adequate to capture the chromium mist. If the mist is not
captured, then it cannot be measured accurately. In addition,
the required ventilation rate is determined based on the surface
area of the tank. Therefore, two tanks with the same capacities
but different surface areas will be vented at different rates.
If the two tanks are plating identical parts, the tank with the
higher ventilation rate will have a lower concentration of
chromium than the tank with a lower ventilation rate. The sample
location will also affect the quantity of emissions measured
because chromic acid mist will impinge on the duct walls and will
lower the amount of chromium measured. For example, if a plating
tank was tested with sample locations directly following the hood
and 15 m (50 ft) downstream of the hood, the emissions measured
at the hood would be higher than those measured 15 m (50 ft)
downstream.
The variability in the emission data for hard and decorative
plating operations is a direct measure of the variability in the
factors discussed above. The only factors that were relatively
constant among the facilities tested were the chromic acid
concentration, plating bath temperature, and surface tension of
the plating bath. As shown in part in Tables 3-8 and 3-9, the
current, voltage, ventilation rate, type and surface area of
parts plated, physical tank parameters, and location of the
sample varied from plant to plant because of differences in the
3-35
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process operation and the layout of the plant. However, there is
less variability in the data among individual test runs at a
given facility because the factors that affect emissions are
fairly constant. For example, at Plant G, there was little to no
variation in the bath operating parameters, the type and surface
area of parts plated, or the current and voltage applied during
each test run. The difference in uncontrolled mass emission
rates between the highest and lowest values among the three test
runs at Plant G was only 0.0085 kg/hr (0.0188 Ib/hr). In
contrast, the mass emission rate for individual test runs at
Plant I varied from 0.072 kg/hr (0.158 Ib/hr) to 0.117 kg/hr
(0.259 Ib/hr). At Plant I, values of the above parameters were
constant, except for minor variations in the workload and current
applied. As expected, the lowest mass emission rate (0.072 kg/hr
[0.158 Ib/hr]) was measured during the test run that also had the
lowest current (5,470 Ah), and the highest mass emission rate
(0.117 kg/hr [0.259 Ib/hr]) was measured during the test run
which had the second highest current (13,000 Ah). This suggests
that the key operating parameter that affects emissions at any
given plant would be the current applied, which is an indicator
of the variation in the type and surface area of parts plated.
3.3.1.5 Emission Factor Development. Correlation analyses
were used to evaluate the relationship between chromium emissions
from hard chromium plating operations and key process operating
parameters. Although small positive correlations were observed
between total hexavalent chromium emissions and both energy input
in ampere-hours and tank surface area, no statistically
significant relationships were found. Based on engineering
judgment, total energy input (ampere-hours) was selected as the
best measure of process rate for electroplating operations
because (l) emission generating mechanisms are related directly
to energy input, and (2) energy input can be measured accurately.
Emission data were normalized for different process rates and
expressed in units of milligrams of chromium per ampere-hour
(mg/Ah). Subsequent analyses of the test data indicated that the
variability in process emission rates between plants was much
3-36
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greater than the variability in process emission rates for
different test runs at the same plant. These results suggest
that operating differences between plants have a greater impact
on emissions than does normal process measurement variability.
Consequently, the best measure of typical chromium emission rates
is the average plant-specific process emission rate. The average
hexavalent chromium emission factors presented in Tables 3-10 and
3-11 for each source test were calculated by the following
equation:
(Emission rate, kg/hr)(Sample time, hr)
Emission factor, mg/Ah = x 106
(Current, Ah)
Based on the existing data, an uncontrolled emission factor of
10 mg/Ah (0.15 gr/Ah) is considered to be representative of
uncontrolled hexavalent chromium emissions from a hard chromium
electroplating operation and an uncontrolled hexavalent chromium
emission factor of 2 mg/Ah (0.03 gr/Ah) is considered to be
representative of uncontrolled emissions from a decorative
chromium electroplating operation.
3.3.2 Chromic Acid Anodizing Operation
Data on uncontrolled hexavalent chromium emissions from
chromic acid anodizing operations based on direct measurement are
currently not available. However, an uncontrolled emission
estimate was developed based on a mass balance around a once-
through scrubber system used to control emissions from a chromic
acid anodizing operation. The mass balance procedure is
described in the following sections.
The chromic acid anodizing facility examined was a small job
shop that performs chromic acid anodizing of aircraft and
electronic parts. The chromic acid anodizing tank was 3.5 m
(11.5 ft) long, 0.61 m (2.0 ft) wide, and 0.91 m (3.0 ft) deep.
The tank capacity was approximately 1,890 L (500 gal). The
anodizing solution in the tank contained chromic acid in a
concentration of approximately 60 to 75 g/L (8 to 10 oz/gal) of
water. The operating temperature ranged from 35° to 38°C (95° to
3-37
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100°F). The voltage was applied step-wise until a level of
40 volts was reached. This level was maintained for the
remainder of the anodizing time. The current typically ranged
from 200 to 300 amperes and the anodizing time was approximately
1 hour. For a more detailed description of the facility,
Plant "0, refer to Appendix C.
3.3.2.1 Sampling Procedures. Composite samples
representative of the scrubber influent, scrubber effluent, and
anodizing solution were obtained for each of four 1-hour
anodizing cycles. Each sample consisted of four grab samples
that were collected approximately 15, 30, 45, and 60 minutes into
each anodizing cycle. The composite samples obtained during the
tests were analyzed for both hexavalent and total chromium.
The scrubber water flow rate was also measured periodically
by placing a 19-L (5-gal) container into the outlet stream and
recording the amount of time required to fill the container. The
temperature, operating voltage, and operating current of the
anodizing solution; the number and types of parts anodized during
each anodizing cycle; and the outlet water flow rate of the
scrubber were recorded during each anodizing cycle. The average
values for each of these parameters is shown in Table 3-12.
TABLE 3-12. PROCESS OPERATING PARAMETERS MONITORED DURING
SAMPLING AT THE CHROMIC ACID ANODIZING FACILITY
Run No.
1
2
3
4
Average
Anodizing bath
temperature,
°C (°F)
35 (95)
35 (95)
35 (95)
35 (95)
35 (95)
Current ,
amperes
80-100
20-40
20
100
20-100
Voltage,
volts
35
36
37
36
36
Outlet
water
flow rate,
L/min
(gal/min)
7.5 (2.0)
7.2 (1.9)
7.2 (1.9)
7.5 (2.0)
7.5 (2.0)
3-38
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3.3.2.2 Results of Mass Balance. The results of the sample
analyses were used to perform a chromium mass balance around the
scrubber to estimate uncontrolled chromium emissions. The
following equation was used to solve for the uncontrolled
chromium mass emission rate:
M = [(Qw)(CW)]/E
where:
M = uncontrolled chromium mass emission rate, kg/hr
(Ib/hr);
Qw = outlet water flow rate of scrubber, L/hr (gal/hr);
Cw = chromium concentration of outlet water stream,
kg/L (Ib/gal); and
E = efficiency of the scrubber, 90 percent.
The estimated uncontrolled chromium emission rates and
workload descriptions for each test run are presented in
Table 3-13. The uncontrolled chromium emission rate ranged from
1.5 x 10"4 kg/hr (3.3 x 10'4 Ib/hr) to 2.5 x 10'3 kg/hr
(5.5 x 10 "3 Ib/hr). The variation in the estimated uncontrolled
chromium emission rates is directly related to the total surface
area and configuration of the parts anodized during each test
run. The same type of aircraft parts were anodized during run
Nos. 2 and 3 with 22 parts anodized during run No. 2 and 16 parts
anodized during run No. 3. The workload decreased 27 percent
from run No. 2 to run No. 3 with a corresponding decrease of
61 percent in the uncontrolled emission rate. The types of parts
anodized during both run Nos. 1 and 4 were similar and consisted
of racks of small aircraft and electronic parts, with 14 racks of
parts anodized during run No. 1 and 17 racks of parts anodized
during run No. 4. The workload increased 18 percent from run
No. 1 to run No. 4 with a corresponding increase of 24 percent in
the uncontrolled chromium emission rate.
The average uncontrolled emission rate for run Nos. 2 and 3
is 2.7 x 10"4 kg/hr (5.9 x 10"4 Ib/hr), and the average
uncontrolled emission rate for run Nos. 1 and 4 is
2.2 x 10~3 kg/hr (4.9 x 10"3 Ib/hr). The average of run Nos. 2
and 3 is only 12 percent of the average of run Nos. 1 and 4,
3-39
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which suggests that both total surface area and configuration of
parts substantially affect the amount of uncontrolled chromium
emissions.
TABLE 3-13. UNCONTROLLED CHROMIUM MASS EMISSION RATES BASED ON
'HEXAVALENT AND TOTAL CHROMIUM CONCENTRATION OF OUTLET SCRUBBER
WATER AT THE CHROMIC ACID ANODIZING FACILITY
Run No.
Uncontrolled chromium
emission rate at
scrubber efficiency of
90 percent,
kg/hr (lb/hr)a
No. of parts or racks
anodized
Type of part anodized
1
2
3
4
Average
0.0019 (0.0042)
0.00039 (0.00086)
0.00015 (0.00033)
0.0025 (0.0055)
0.0012 (0.0026)
14 racks
22 parts
16 parts
17 racks
Small aircraft and electronic
Aircraft parts
Aircraft parts
Small aircraft and electronic
parts
parts
aTotal and hexavalent chromium concentrations in scrubber water were equal.
The average uncontrolled chromium emission rate for all runs
was 1.2 x 10"3 kg/hr (2.6 x 10~3 Ib/hr). Even though the data
show a wide range of uncontrolled emission rates due to the
different workloads during each run, it is reasonable to average
the estimated emissions because workload variations are common in
the industry.
3.3.2.3 Emission Factor Development. The factors that
affect the hexavalent chromium emission rate from chromic acid
anodizing tanks are the types and surface area of parts anodized,
surface area of the anodizing tank, orientation of parts within
the anodizing tank, plating bath temperature, chromic acid
concentration, and surface tension of the anodizing solution.
These factors affect emissions in the same manner as they affect
emissions from plating baths (see Section 3.3.1.4). However, a
key difference between chromium plating and anodizing is the
effect of the current applied on emission generation. In
plating, the current does not vary across the plating time and,
therefore, the chromium mist is generated at a constant rate. In
3-40
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anodizing, the current varies because the oxide layer that is
built up on the anodized part is resistant to current flow, so
that the current peaks at the beginning of the anodizing cycle
and decreases as the thickness of the oxide layer (or resistance)
builds up. Therefore, the amount of hydrogen gassing or chromium
misting decreases over the anodizing time as the current
decreases. Because of the current fluctuations in anodizing, the
average current supplied to the anodizing tank is difficult to
determine, which in turn makes it difficult to develop an
emission factor based on energy input.
The other predominant factors that affect emissions from
chromic acid anodizing operations are the type and surface area
of parts anodized, the surface area of the anodizing tank, and
the chromic acid concentration. The chromic acid concentration
is fairly constant for all anodizing baths and does not account
for variations in the process load. The surface area of the
parts is probably the best measure of emissions; however, the
surface area may or may not be known and is difficult to
quantify. Therefore, tank surface area was selected as the best
measure of emissions because (1) energy input for anodizing
operations cannot be accurately measured, and (2) tank surface
area is a constraint on the workload, which is related to
emission-generating mechanisms. Based on the results of the mass
balance presented previously, the uncontrolled hexavalent
chromium emission factor of 6.0 x 10"4 kg/hr/m of tank surface
area (1.2 x 10"4 lb/hr/ft2 of tank surface area) can be used to
characterize emissions from this type of operation.
3.4 EXISTING STATE REGULATIONS
Many States use their air toxics programs as a basis for
establishing policy or guidelines for limiting chromium
emissions. In other States, chromium emission sources are
subject only to permit requirements. Fourteen States have
adopted or proposed regulations for the control of chromium
emissions to the atmosphere. The regulations for these States
are discussed below.
3-41
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3.4.1 California
The State of California has historically been a leader in
developing and adopting regulations for the control of airborne
toxics. Because of this, a detailed account of the California
Air Resources Board's (CARS's) adopted regulations for hexavalent
chromium emissions is presented. Their control measure applies
to chromium plating and chromic acid anodizing operations.
California has determined that, in California, large hard
chromium plating and chromic acid anodizing facilities are
responsible for 50 percent of all chromium plating emissions;
medium hard chromium plating and chromic acid anodizing
facilities are responsible for 46 percent; and small hard
chromium plating and chromic acid anodizing shops and all
decorative chromium plating shops are responsible for 4 percent.
The levels of control required are based on the type of plating
done and the amount of hexavalent chromium emitted.72
Hard chromium plating and chromic acid anodizing facilities
emitting up to 0.91 kg/yr (2 Ib/yr) (small shops) and all
decorative chromium plating shops are required to achieve a level
of control (95 percent) that is less stringent than BACT. Medium
hard chromium plating and chromic acid anodizing shops--those
emitting more than 0.91 kg/yr (2 Ib/yr) but less than 4.5 kg/yr
(10 Ib/yr)--must achieve a 99 percent control efficiency,
equivalent to that believed to be attainable by BACT. Large hard
chromium platers and chromic acid anodizers (emitting 4.5 kg/yr
[10 Ib/yr] or more) must achieve a level of control
(99.8 percent), which is beyond currently demonstrated BACT.
This control efficiency has been demonstrated for control of acid
mists in other industries. 2
As alternatives to control efficiency requirements, CARB has
set emission limits that correspond to each control efficiency
level. These are based on milligrams of hexavalent chromium
emitted per ampere-hour of electrical current use. For the
95 percent control level, the corresponding emission limit is
0.15 mg/Ah (0.002 gr/Ah). The emission levels corresponding to
3-42
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99 and 99.8 percent control are 0.03 and 0.006 mg/Ah (0.0005 and
0.00009 gr/Ah), respectively.
There are 41 local districts in California. When an
airborne toxic control measure (regulation) is adopted by CARB,
all local districts must propose and adopt the measure or an
equally effective or more stringent measure. The CARB regulation
for controlling hexavalent chromium emissions from chromium
plating and anodizing operations was adopted in February 1988 and
approved by California's Office of Administrative Law (OAL) in
December 1988. The effective date of the measure was 30 days
following OAL's approval, and the districts had to adopt a
measure at least as stringent by July 1989.73
3.4.2 Connecticut
A chromium regulation has been adopted by Connecticut and
applies to new and existing facilities. The emission limit for
hexavalent chromium is 0.25 ^g/m3 (1.1 x 10"7 gr/ft3) as chromium
(8-hour average). The point of compliance is usually at the
property line. If the distance to the property line is very
short, then the point of compliance may be up to 10 m (33 ft)
beyond the property line. Sources exceeding the emissions limit
must install control technology that will enable them to comply
with the regulation.74
3.4.3 Kentucky
Kentucky's chromium regulations specify that existing
sources emitting Cr+^ must use reasonably available control
technology (RACT). The BACT is required for new and modified
sources with Cr+6 emissions. Other chromium compounds are
regulated only for new and modified sources. The ambient air
concentration limit is based on the threshold ambient limit (TAL)
for chromium compounds. For sources operating 40 hours per week
or less, the emission limit is equal to the TAL for that compound
divided by 100. For sources operating 168 hours per week, the
limit is equal to the TAL divided by 42. Mathematical
interpolation is used to determine limits for sources operating
between these limits. The limits apply to the maximum ambient
ground level concentration outside the property line.75'76
3-43
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3.4.4 Maine
The regulations for this State have been adopted. The
maximum 24-hour concentration for total chromium must not exceed
0.3 /*g/m3 (1.3 x 10~7 gr/ft3), and the annual geometric mean must
not exceed 0.05 /xg/m3 (2.2 x 10"^ gr/ft3) . The maximum 24-hour
concentration for hexavalent chromium must not exceed the minimum
detection level of an acceptable analytical procedure for
measuring hexavalent chromium in the ambient air, or 1.0 ng/m3
(4.4 x 10"10 gr/ft3), whichever is greater.77
3.4.5 Maryland
Maryland has promulgated a regulation that includes total
chromium and hexavalent chromium emissions. The regulation is
based on EPA's unit risk factor for chromium and employs a
screening level (vs. minimum acceptable level). The screening
level for total chromium and hexavalent chromium is 5 /tcg/m3
(2.2 x 10"6 gr/ft3) (8-hour average). Offsite concentrations of
hexavalent chromium cannot exceed 0.0008 pig/m3
(3.5 x 10"10 gr/ft3) (annual average). For total chromium, there
is no annual average level. If sources cannot meet the level for
hexavalent chromium, they must get a special permit that requires
them to (l) perform a source-specific risk assessment,
(2) demonstrate that all hexavalent chromium emission sources on
the premises are controlled using BACT for toxic air pollutants,
and (3) advertise in the newspaper to provide an opportunity for
a public hearing. These procedures enable the State to make
7ft
decisions on a case-by-case basis.'0
3.4.6 Nevada
Emissions of all chromium compounds and chromium valence
states for which a TLV exists are regulated. The regulations
apply to new sources now and to existing sources as their
operating permits are renewed. The ambient concentration limit
is the TLV divided by 42 for each of these compounds. The point
of compliance is the plant property line. If the concentrations
are exceeded, control technology that has been proposed by the
applicant and approved by the agency director must be installed
at the plant.79
3-44
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3.4.7 New Hampshire
This State's proposed regulation for hexavalent chromium
would limit emissions to 0.12 /*g/m3 (5.2 x 10~8 gr/ft3) (24-hour
average) with the concentrations measured at the plant boundary.
The regulation would first apply ±o new sources only, and
existing sources will eventually be regulated.8^
3.4.8 North Carolina
This State has proposed regulations for the control of
emissions of hexavalent chromium. The regulations apply to new
and existing sources and would limit the ambient concentration to
an annual average of 8.3 x 10 ~8 mg/m3 (3.6 x 10'11 gr/ft3)
determined at the property line.81
3.4.9 Rhode Island
The adopted regulation applies to new and existing sources.
A total chromium emission level of 9.0 x 10~5 fig/m3
(3.9 x 10"11 gr/ft3) is considered acceptable under any
conditions. If the level of emissions reaches 9.0 x 10 /xg/m3
(3.9 x 10'10 gr/ft3), the source must apply lowest achievable
emission rate (LAER) technology. Emissions are determined by
modeling at the point of maximum impact off the property. If the
source is not able to speciate chromium emissions, they are
assumed by the State to be all hexavalent chromium.82
3.4.10 South Carolina
This State's proposed regulation would apply to new sources
only and would limit chromium emissions to the TLV divided
by 200, with the concentrations determined at the plant property
line.83
3.4.11 Utah
Utah has existing regulations stating that any new or
modified source of chromium emissions is required to install
BACT.84
3.4.12 Vermont
This State has adopted a regulation for total chromium
emissions. It specifies that sources emitting total chromium
must meet a threshold level of 3.2 x 10"6 kg/8 hr
(7.1 x 10"6 lb/8 hr) of chromium emissions before they are
3-45
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subject to the regulation. Sources exceeding this action level
must install hazardous most stringent emission rate (HMSER)
control technology and are subject to the ambient air quality
standard of 8.5 x 10"5 jtg/m3 (3.7 x 10"11 gr/ft3) , determined at
the point of maximum impact.85
3.4.13' Virginia
This State's adopted regulations apply to new and existing
sources. For chromium with valence states listed as
carcinogenic, the 24-hour average emission limit is the TLV
divided by 100; for valence states not listed as carcinogenic,
the 24-hour average emission limit is the TLV divided by 60. The
point of compliance is the fenceline.86
3.4.14 Wisconsin
Water-soluble hexavalent chromium is regulated as a toxic
air pollutant for new and existing sources. The point of
compliance is the property line. The de minimis level for
sources with stack heights of less than 25 ft is 0.019 kg/hr
(4.08 x 10"2 Ib/hr) (24-hour average) and 0.077 kg/hr
(17.04 x 10"2 Ib/hr) (24-hour average) for stack heights of
greater than 25 ft. The acceptable ambient concentration for
water-soluble hexavalent chromium is 1.2 /*g/m3
(5.2 x 10"7 gr/ft3). Water-insoluble hexavalent chromium is
regulated as a known human carcinogen for new and existing
sources. The de minimis level for new sources (and existing
sources, eventually) is 0.91 kg/yr (2 Ib/yr). If this level is
P <-i
exceeded, the source must apply LAER technology. '
3-46
-------
3.5 REFERENCES FOR CHAPTER 3
1. Memo from Hester, C., MRI, to Smith, A., EPA/ISB. Bases of
Risk Assessment Inputs for Chromium Electroplating
Operations. June 10, 1988. p. 10.
2. Memo from Hester, C., MRI, to Smith, A., EPA/ISB. Bases of
Risk Assessment Inputs for Chromic Acid Anodizing
Operations. June 10, 1988. p. 9.
3. Decorative Chromium Plating. American Electroplaters
Society, Inc. 1980. p. 4.
4. Logozzo, A. W., and M. Schwartz. Hard Chromium Plating.
American Electroplaters Society, Inc. 1984. p. 9.
5. Graham, K. A. Electroplating Engineering Handbook
(3rd ed.). New York, Van Nostrand Reinhold Co, 1971.
p. 138.
6. Graham, K. A. Electroplating Engineering Handbook. New
York, Reinhold Book Co. 1962. p. 162.
7. Reference 6, pp. 162-163.
8. Reference 5, p. 684.
9. Reference 4, p. 13.
10. Reference 4, p. 13.
11. Allen, W. Hard Chromium Plating: How Difficult? Products
Finishing. March 1988. p. 69.
12. Chromium Emissions from Chromium Electroplating Operations--
Technical Report. November 1, 1985. p. 3.
13. Reference 3, p. 7.
14. Reference 3, p. 8.
15. Reference 3, p. 2.
16. Lowenhein, F. A. Electroplating. New York, McGraw-Hill
Book Co. 1978. p. 196.
17. Mackey, R. W. and D. A., Swalheim. Cyanide Copper Plating.
American Electroplaters Society, Inc. 1969. pp. 7, 14.
18. Reference 17, p. 4.
19. Reference 16, pp. 201-202.
3-47
-------
20. Reference 16, p. 202.
21. Metal Finishing. Guidebook and Directory Issue. 88(1A).
January 1990. p. 203.
22. Olsen, Alan E. Bright Acid Sulfate Copper Plating.
American Electroplaters Society, Inc. 1970. p. 3.
23. Soule, R. D. Electroplating. In: Industrial Hygiene
Aspects of Plant Operations, Vol. 2, Unit Operations and
Product Fabrication, Cralley, L. V. and L. J. Cralley
(eds.). New York, Macmillan Publishing Company. 1984.
p. 81.
24. Reference 23, p. 79.
25, Dennis, J. K., and T. E. Such. Nickel and Chromium Plating
(2nd ed.). London, England Butterworth and Company. 19.86.
p. 232.
26. Reference 23, p. 84.
27. DiBari, G. A., and J. Horner. Nickel Plating. American
Electroplaters Society, Inc. 1985. p. 4.
28. Reference 12. p. 3.
29. Reference 25, p. 179.
30. Reference 25, p. 287.
31. Reference 25, p. 289.
32. Reference 25, p. 290.
33. Reference 25, pp. 272, 294-295.
34. Schwartz, M. Anodizing Aluminum and Its Alloys. American
Electroplaters Society. 1985. p. 15.
35. Reference 6, p. 432.
36. Reference 6, pp. 162, 427.
37. Darrin, M., and L. G. Tubbs. Dyeing Chromic Acid Anodized
Aluminum. Metal Finishing. September 1943. p. 550.
38. Brace, A. W. The Technology of Anodizing Aluminum.
Teddington, Robert Draper, Ltd. 1968. p. 54.
39. Reference 34, p. 17.
3-48
-------
40. Wernick, S., and R. Pinner, Surface Treatment and Finishing
of Light Metals, Metal Finishing. June 1955. p. 92.
41. Telecon. Cassidy, M., MRI, with Kellett, J., Boeing
Commercial Airplane Company. February 27, 1989.
Information on chromic acid anodizing process.
42. Reference 6, p. 429.
43. Reference 6, p. 429.
44. Mozley, P. P. The Chromic Acid Anodizing Process. Metal
Finishing. June 1941. p. 302.
45. Prelinger, H. A. The Chromic Acid Anodizing Bath and Its
Control. Metal Finishing. November 1960. p. 59.
46. Reference 6, p. 433.
47. Brimi, M. A., and J. R. Luck. Electrofinishing. New York,
American Elsevier Publishing Co. 1965. p. 77.
48. Reference 6, p. 430.
49. Smart, D., T. E. Such, and S. J. Wake. A Novel Trivalent
Chromium Electroplating Bath. Bulletin of the Institute of
Metal Finishing. £1:106 p. 106.
50. Snyder, D. Trivalent Chromium Plating: The Second Decade.
Product Finishing. March 1988. p. 59-60.
51. Reference 50, p. 63.
52. Reference 50, pp. 64-65.
53. Reference 50, p. 65.
54. Letter from Vervaert, A., EPA/ISB, to Masarik, D., Englehard
Corporation. November 17, 1988. Trip report for Englehard
Corporation, Beachwood and Cleveland, Ohio. p. 3.
55. Cost Enclosure for Decorative Chromium Electroplating
Processes: Harshaw/Filtrol Partnership. Prepared for U. S.
Environmental Protection Agency, Research Triangle Park,
North Carolina, by Dennis Masarik, Manager of Technical
Services. June 22, 1987. p. 3.
56. Tomaszewski, T., and R. Fischer. Trivalent Chromium: A
Commercially Viable Alternative. Occidental Chemical Corp.
p. 5.
57. Reference 56, pp. 5-6.
3-49
-------
58. Eppensteiner, F., and M. Jenkins. Chromate Conversion
Coatings. In: Metal Finishing, Guidebook and Directory
Issue 1990. 8£(1A) :433-441.
59. Biestek, T., and J. Weber. Electrolytic and Chemical
Conversion Coatings. Warsaw, Portcullis Press Ltd. 1976.
p. 10.
60. Reference 5, pp. 682-686.
61. Chromium Electroplaters Test Report: Greensboro Industrial
Platers, Greensboro, North Carolina. Entropy
Environmentalists, Inc., Research Triangle Park, North
Carolina. Prepared for U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina. EMB
Report 86-CEP-l. March 1986.
62. Chromium Electroplaters Test Report: Consolidated Engravers
Corporation, Charlotte, North Carolina. Peer Consultants,
Inc., Rockville, Maryland. Prepared for U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
EMB Report 87-CEP-9. May 1987.
63. Chromium Electroplaters Test Report: Able Machine Company,
Taylors, South Carolina. PEI Associates, Inc., Cincinnati,
Ohio. Prepared for U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina. EMB
Report 86-CEP-3. June 1986.
64. Emission Test Report: Roll Technology Corporation,
Greenville, South Carolina. Peer Consultants, Inc., Dayton,
Ohio. Prepared for U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina. EMB
Report 88-CEP-13. August 1988.
65. Chromium Electroplaters Test Report: Precision Machine and
Hydraulic, Inc., Worthington, West Virginia. Peer
Consultants, Inc., Dayton, Ohio. Prepared for the U. S.
Environmental Protection Agency, Research Triangle Park,
North Carolina. EMB Report 88-CEP-14. September 1988.
66. Chromium Electroplaters Test Report: Hard Chrome
Specialists, York, Pennsylvania. Peer Consultants, Inc.,
Dayton, Ohio. Prepared for U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina. EMB
Report 89-CEP-15. February 1989.
3-50
-------
67. Chromium Electroplaters Test Report: Piedmont Industrial
Platers, Statesville, North Carolina. Entropy
Environmentalists, Inc., Research Triangle Park, North
Carolina. Prepared for U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina. EMB
Report 86-CEP-4. August 1986.
68. Chromium Electroplaters Test Report: Steel Heddle,. Inc.,
Greenville, South Carolina. PEI Associates, Inc.,
Cincinnati, Ohio. Prepared for U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
EMB Report 86-CEP-2. June 1986.
69. Chromium Electroplaters Test Report: Fusion, Inc., Houston,
Texas. Peer Consultants, Inc., Dayton, Ohio. Prepared for
the U. S. Environmental Protection Agency, Research Triangle
Park, North Carolina. EMB Report 89-CEP-16. May 1989.
70. Chromium Electroplaters Test Report: CMC Delco Products
Division, Livonia, Michigan. Peer Consultants, Inc.,
Rockville, Maryland. Prepared for U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
EMB Report 87-CEP-7. March 1987.
71. Chromium Electroplaters Test Report: Automatic Die Casting,
St. Clair Shores, Michigan. Peer Consultants, Inc., Dayton,
Ohio. Prepared for U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina. EMB
Report 88-CEP-ll. April 1988.
72. State of California Air Resources Board. Staff Report:
Initial Statement of Reasons for Proposed Rulemaking.
Proposed Airborne Toxic Control Measure for Emissions of
Hexavalent Chromium from Chrome Plating and Chromic Acid
Anodizing Operations. January 1988.
73. Telecon. Cassidy, M., MRI, with Holiday, K., California Air
Resources Board. February 24, 1989. Information on
California's control measure for emissions of hexavalent
chromium from chrome plating and chromic acid anodizing
operations.
74. Telecon. Cassidy, M., MRI, with Gove, J., Connecticut
Department of Environmental Protection Air Compliance Unit.
March 14, 1989. Information on Connecticut's State
regulation for chromium.
75. Telecon. Barker, R., MRI, with Saaid, H., Kentucky Resource
and Environmental Protection Cabinet, Division of Air
Pollution Control. October 2, 1986. Information on
Kentucky's State regulation for chromium.
3-51
-------
76. State of Kentucky Natural Resources and Environmental
Protection Cabinet, Department of Environmental Protection,
Division of Air Pollution--Regulations 401 KAR 63:021 and
401 KAR 63:022.
77. Telecon. Cassidy, M., MRI, with Severance, R., Maine
Department of Environmental Protection, Bureau of Air
Quality Control. August 28, 1986. Information on Maine's
State regulation for chromium.
78. Telecon. Cassidy, M., MRI, with Aburn, T., Maryland
Department of Health and Mental Hygiene, Air Management
Administration. March 14, 1989. Information on Maryland's
State regulation for chromium.
79. Telecon. Cassidy, M., MRI, with Shifley, L., Nevada
Department of Conservation and Water Resources, Air Quality
Bureau. March 14, 1989. Information on Nevada's State -
regulation for chromium.
80. Telecon. Barker, R., MRI, with Andrews, R., New Hampshire
Air Resources Agency. October 2, 1986. Information on New
Hampshire's State regulation for chromium.
81. Telecon. Cassidy, M., MRI, with Hageman, R., North Carolina
Department NRCD, Division of Environmental Management.
March 14, 1989. Information on North Carolina's State
regulation for chromium.
82. Telecon. Cassidy, M., MRI, with Morin, B., Rhode Island
Department of Environmental Management, Division of Air and
Hazardous Materials. March 13, 1989. Information on Rhode
Island's State regulation for chromium.
83. Telecon. Cassidy, M., MRI, with Pearson, 0., South Carolina
Department of Health and Environmental Control, Bureau of
Air Quality Control. August 26, 1986. Information on South
Carolina's State regulation for chromium.
84. Telecon. Barker, R., MRI, with McNeil, D., Utah Department
of Health, Bureau of Air Quality. October 7, 1986.
Information on Utah's State regulation for chromium.
85. Telecon. Cassidy, M., MRI, with Garabedian H., Vermont
Agency of Environmental Conservation, Air Pollution Control
Division. March 10, 1989. Information on Vermont's State
regulation for chromium.
86. Telecon. Cassidy, M., MRI, with Holmes, C., Virginia Air
Pollution Control Board. August 28, 1986. Information on
Virginia's State regulation for chromium.
3-52
-------
87. Telecon. Cassidy, M., MRI, with Rudell, V., Wisconsin
Department of Natural Resources, Bureau of Air Management.
March 13, 1989. Information on Wisconsin's State regulation
for chromium.
3-53
-------
4. EMISSION CAPTURE AND CONTROL TECHNIQUES
This chapter presents a description of the techniques
typically used to capture and control emissions of chromic acid
mist from decorative and hard chromium electroplating and chromic
acid anodizing baths.
4.1 EMISSION CAPTURE TECHNIQUES
Local exhaust ventilation is the most common method used to
capture chromic acid mist from chromium plating and chromic acid
anodizing baths. General ventilation, the exhausting of large
volumes of air from a building or room, is not normally used
because of the toxicity of chromic acid and the need to remove
contaminated air that would accumulate close to the source.
4.1.1 Local Ventilation
Local exhaust ventilation equipment typically used to
capture chromic acid mist from chromium plating and chromic acid
anodizing operations includes lateral (slot) and push-pull
exhaust hoods. Canopy hoods and enclosures are normally not used
because they restrict access to the plating or anodizing tank.
For tanks located where there are no room cross drafts, the
recommended minimum capture air velocity across the liquid
surface of the tank is 46 m/min (150 ft/min) for contaminants
with high hazard potential and a high rate of mist evolution such
as chromic acid.1'2 Capture velocity is the velocity required to
overcome opposing air currents and cause the contaminated air to
flow into the hood. Where room cross drafts occur at the tank
level, the capture velocity should be increased, and baffles
should be installed to mitigate the effects of the cross drafts.
The design ventilation rate for a particular tank is based
on the hood type selected, the capture or control velocity
4-1
-------
selected, and on the aspect (width-to-length) ratio of the tank.
Table 4-1 presents minimum recommended ventilation rates for
tanks with aspect ratios less than 2.0. Ventilating parallel to
the long dimension of a tank with an aspect ratio that exceeds
2.0 is not practicable.1'2
4.1.2 • Lateral Exhaust Systems
All tanks exhausted by means of hoods that do not project
over the entire tank, and in which the direction of air movement
into the hood or hoods is substantially horizontal, are said to
be laterally exhausted. Lateral exhaust systems typically
applied to control chromic acid mist from open-surface tanks
include both single- and double-sided slot hoods. The slot
velocity affects the uniformity of airflow distribution along the
length of the hood. Slot velocities of 610 m/min (2,000 ft/min)
are recommended unless takeoffs (openings where emissions are
exhausted to the duct) are provided. With well-designed, tapered
takeoffs, lower velocities may be used. Multiple takeoffs are
recommended for tanks at least 1.8 m (6.0 ft) in length and are
necessary for tanks at least 3.0m (10 ft) in length to maintain
good capture efficiency.
An example of each type of slot hood is shown in Figures 4-1
and 4-2. Single-sided hoods have a maximum reach across the
width of the tank of about 76 cm (30 in.) while double-sided
hoods have a maximum reach of about 152 cm (60 in.). The
advantage of a lateral slot hood is that it minimizes the space
occupied by the hood when air distribution over a large surface
is needed; the disadvantage is that the high slot velocities
result in a relatively high static pressure loss at the hood
i 9
entry. '^
Push-pull ventilation is recommended for tanks greater than
107 cm (42 in.) in width.1 A diagram of a push-pull system is
presented in Figure 4-3. Push air supplied through slots,
orifices, or nozzles is blown across the width of the tank to
direct contaminated air toward an exhaust hood located on the
opposite side of the tank. The major advantage of push-pull
systems over lateral exhaust systems is that they provide the
4-2
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Figure 4-2.
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same ventilation efficiency while using only about one-half the
volume of air. This efficiency results in smaller air handling
equipment (ductwork and fans) and lower utility and makeup air
requirements. However, push-pull ventilation cannot be used when
plating racks, anode bars, or other obstructions that interfere
with the flow of push air across the tank are present.
4.1,3 Factors Affecting Performance of Local Exhaust Ventilation
Maintaining an adequate ventilation rate is one of the major
factors affecting the performance of ventilation systems. The
ventilation rate must be maintained at a level sufficient to
produce a uniform, horizontal movement of air (across the surface
of the tank) that is capable of capturing and conveying the
contaminated air to the exhaust hood. The capture velocity must
be sufficiently high to compensate for air disturbances across
the tank due to cross drafts in the room. Baffles can be added
to lessen the effects of severe cross drafts.
Another key factor affecting the performance of local
exhaust ventilation is the adequacy of the makeup air supply.
Sufficient makeup air must be introduced to offset or replace air
exhausted from the building. Without sufficient makeup air,
exhaust systems have to work against an increased static pressure
because buildings are under negative pressure, or suction.
Regardless of the types of exhaust fans employed, actual exhaust
rates and capture velocities can be reduced significantly. The
main factors affecting the volumetric flow of makeup air in a
shop include the layout and siting of heat sources and the
physical layout of the building relative to the location of the
tank.
In addition to the factors discussed above, other factors
that affect the performance of a push-pull system include the
amount of push air supplied, the size of the exhaust hood
installed, and the extent to which obstructions are present in
the push air stream path. Too much push air volume or pressure
can result in airflows exceeding the exhaust rate. The exhaust
hood opening must be large enough to intercept the entire cross
4-6
-------
section of the air stream directed to it. Obstructions in the
path of the air stream must be limited to avoid interference.
4.2 EMISSION CONTROL TECHNIQUES
The principal techniques used to control emissions of
chromic acid mist from decorative and hard chromium plating and
chromic acid anodizing operations include add-on control devices
that treat ventilation air and methods, such as the addition of
chemical fume suppressants, that affect the amount of mist
released from the tank. Control devices applied most frequently
include mist eliminators and wet scrubbers. Because of the
corrosiveness of chromic acid, ventilation systems and control
devices are typically made of PVC plastic or fiberglass.
Chemical fume suppressants are typically added to decorative
chromium plating and chromic acid anodizing baths to inhibit
chromic acid misting. Although the use of fume suppressants
alone can be effective, many plants use them in conjunction with
add-on control devices. Polypropylene balls are sometimes added
to hard chromium plating baths to reduce heat loss and
evaporation of the plating solution and, to a limited extent, to
reduce chromic acid misting.
The two major control mechanisms by which contaminants such
as chromic acid mist are removed from ventilation air are
inertial impaction and direct interception. Collection by
inertial impaction involves the collision of large particles with
a stationary surface to which they adhere. In direct
interception, particles attempt to follow the streamline around
the collection surface, but, due to their size and relative
velocity, they are intercepted by the fluid layer that surrounds
the collection surface. Collected liquid droplets drain to the
bottom of the collection device due to gravity. Particles that
have been wetted increase in mass and are more easily removed
from the gas stream than are smaller particles. Wetted particles
may be separated from the gas stream by impingement against
surfaces placed in the path of the gas flow, by centrifugal
action's throwing particles to the outer walls of the collector,
or by simple gravitational settling. Most control devices are
4-7
-------
flushed with water on a periodic or continual basis to clean the
collection surfaces.
4.2.1 Mist Eliminators
The types of mist eliminators most frequently used at
chromium electroplating and anodizing facilities include chevron-
blade and mesh-pad units. Inertial impaction and direct
interception are the principal control mechanisms by which both
types of mist eliminators collect chromic acid droplets from gas
streams. Mist eliminators are usually operated as dry units that
are periodically washed with water to clean the impaction media.
4.2.1.1 Chevron-Blade Mist Eliminators. Chevron-blade mist
eliminators consist of one or more sets of parallel, chevron-
shaped baffles (blades) arranged in a horizontal-flow
configuration. Horizontal-flow chevron-blade mist eliminators
typically are used to control chromic acid mist because the
horizontal-flow configuration is more effective than the
vertical-flow configuration for the high inlet velocities and
pollutant loadings common for chromium plating operations.
Diagrams of typical units with single and double sets of blades
are presented in Figures 4-4 and 4-5, respectively. Each blade
changes the direction of the gas flow four times, which causes
chromic acid droplets to impinge on the surface of the blades as
a result of inertial force. Water sprays mounted at the inlet of
the mist eliminator and directed toward the blades are activated
periodically to wash off the chromic acid that has built up on
the blades. During washing, the fan should be turned off to
prevent water droplets from being drawn through the stack and
discharged to the atmosphere. In most instances, the wash water
is drained to the plating tank to make up for evaporative losses
of plating solution and to recover chromic acid. Otherwise, the
wash water is drained to a wastewater treatment system.
Two blade designs commonly used are overlapping and
sinusoidal wave. A schematic of each design is shown in
Figure 4-6. The overlapping design consists of a set of blades
with overlapping edges. In contrast, the sinusoidal wave design
consists of a set of blades with rounded edges and catchments
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GAS STREAM
OVERLAPPING
BLADES SERVE AS
CATCHMENTS
CONTROLLED
GAS STREAM
DROPLETS TO COLLECTION SUMP
a) Overlapping-type blades.
CATCHMENTS
MIST-LADEN
GAS STREAM
CONTROLLED
GAS STREAM
DROPLETS TO COLLECTION SUMP
b) Sinusoidal wave-type blades.
Figure 4-6. Blade designs for chevron-blade mist eliminators.
4-11
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located between the rounded edges. The overlapping edges, or
catchments, act as collection troughs for droplets and facilitate
drainage of the droplets into a collection sump.
Factory-assembled units are available for gas flow rates
from 14 to 1,700 standard m3/min (500 to 60,000 standard
ft3/min). Units are designed to maintain gas velocities through
the mist eliminator between 120 to 270 m/min (400 to 900 ft/min).
Blades typically range from 15 to 30 cm (6 to 12 in.) in depth.
The spacing between blades may vary but is normally 3.18 cm
(1.25 in.). The static pressure drop across a mist eliminator
with one set of blades and with two sets of blades is about
0.20 kPa (0.75 in. w.c.) and 0.5 kPa (2 in. w.c.), respectively.
Control device vendors estimate that removal efficiencies range
from 80 to 90 percent.6
4.2.1.2 Factors Affecting Performance of Chevron-Blade Mist
Eliminators. Major factors that affect the performance of
chevron-blade mist eliminators include the face velocity of the
gas stream across the blades, the spacing between blades, and the
tightness of seals between the blades and the walls of the unit.
Gas stream velocities must be maintained'within design
specifications to maximize the operating efficiency of the unit.
Gas velocities less than the specified minimum (typically
120 m/min [400 ft/min]) will not provide the inertial force
required to maximize impingement of chromic acid droplets on the
blades, and gas velocities greater than the specified maximum
(typically 270 m/min [900 ft/min]) may cause droplets to become
reentrained in the gas stream. The spacing of the blades is also
an important factor. If the blades are too close together, the
unit could plug; if the blades are too far apart, portions of the
gas stream could travel through the unit with little or no change
in direction, which could result in breakthrough of chromic acid
droplets. Also, the blades must be sealed tightly to the walls
of the unit to prevent contaminated gases from by-passing the
chevron blades.
Another important factor affecting the performance of
chevron-blade mist eliminators is the frequency of washing. The
4-12
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unit should be washed for 10 minutes at least once per day.
During washing, the fan must be turned off to prevent water
droplets from being drawn through the stack, and discharged to the
atmosphere.
4.2.1.3 Mesh-Pad Mist Eliminators. A diagram of a mesh-pad
mist eliminator is presented in Figure 4-7. Mesh-pad mist
eliminators consist of layers of interlocked filaments densely
packed between two supporting grids. The principal control
mechanisms are inertial impaction and direct interception.
Inertial impaction occurs when particles larger than about 3 juti
(0.12 mil), traveling with sufficient velocity, collide with the
filaments and adhere to their surface. Other particles, because
of their size and relative velocity, are intercepted by the fluid
layer surrounding the surface of the filament. Collected liquid
droplets flow along the fibers to a point where adjacent
filaments cross. These crossover points rapidly become loaded
with liquid, and droplets drain to the bottom of the mist
eliminator as a result of gravity.
The mesh pads consist of thin, multiple layers of interwoven
fibers. These layers are compacted and fastened together with
thin filaments. Three mesh pad weave designs are available, as
follows: (1) layers with a crimp in the same direction (each
.layer is actually a nested double layer), (2) layers with a crimp
in alternate directions, and (3) spiral-wound layers. The
filament size depends on the application and can vary from about
0.015 cm (0.006 in.) in diameter for fine wire pads to 0.38 cm
(0.15 in.) in diameter for some plastic fibers. Pad thicknesses
vary from 10 to 15 cm (4 to 6 in.), but occasionally pads as
thick as 30.5 cm (12 in.) are used.8 Mesh densities are
generally reported in terms of bulk density (mass per unit
volume) because it is easier to determine than surface area-to-
volume ratio. Typical bulk mesh densities range from 48 to
529 kg/m3 (3 to 33 lb/ft3).9
Although design gas velocities across mesh pads depend on
the type of mesh material (fiber diameter and configuration),
typical velocities range from 180 to 275 m/min (600 to
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900 ft/min) for vertical-flow units and from 275 to 420 m/min
(900 to 1,380 ft/min) for horizontal-flow units.10
Often two mesh-type separators in series are used to remove
particles in the 1 to 5 fim (0.04 to 0.20 mil) diameter range.
The first mesh, normally made of .fine fibers, coalesces the small
drops, and the second mesh, made of standard fibers, removes
them. The first mesh is operated beyond the flooding velocity
and the second under flooding velocity.11
In the past, mesh-pad mist eliminators were not frequently
used to control chromic acid mist because of the tendency of the
units to plug at high inlet loadings. These units consisted of
one mesh pad, approximately 15 cm (6.0 in.) thick with a pressure
drop of 0.25 kPa (1.0 in. w.c.). The units were installed for
vertical gas flow through the unit and were not equipped with a
spray system to clean the pad. This type of configuration was
not recommended by vendors for use in chromic acid mist control
because of the plugging tendency of the unit.12 However, in
recent years, mesh-pad mist eliminators equipped with internal
spray systems to clean the pads have been developed, avoiding
potential plugging problems. These newer units contain multiple
mesh pads in series that are designed to remove chromic acid mist
in stages. The first stage removes the bulk of the mist, which
is comprised of fairly large particles (above 5 jtm [0.20 mil]),
and the second stage removes the smaller particles (between 3 and
5 nm [0.12 and 0.20 mil]). Because the internal spray system
protects the pads from plugging, these units contain pads with a
smaller fiber diameter than the older models. As a result of the
smaller diameter, the mesh pads are more compact and, therefore,
have a higher pressure drop (0.62 kPa [2.5 in. w.c.]). Instead
of vertical gas flow, these units are installed for horizontal
gas flow through the unit, which allows for better drainage. In
addition, these units are designed so that the pads can be
removed and cleaned. This feature helps prevent plugging and
extends the life of the pad material. The vendor of this
technology estimates a control device efficiency between 96 and
99 percent.13 Because of the reduction in the plugging potential
4-15
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and its associated maintenance problems, the use of mesh-pad mist
eliminators in controlling chromic acid mist has increased.
4.2.1.4 Factors Affecting Performance of Mesh-Pad Mist
Eliminators. One of the major factors that affects mesh-pad mist
eliminator performance is the tendency of the unit to plug. The
mesh pad must be flushed frequently with water to prevent chromic
acid buildup and eventual plugging. Mesh-pad mist eliminators
should be washed down at least once a day.
Velocity of the gas stream and the particle size of the
entrained pollutant are additional factors that affect the
performance of the mesh pad assembly. Because the pad consists
of stationary surfaces, the entrained particles must have
adequate velocity to collide with the filaments. As velocity
increases, collection of particles through inertial impaction
increases. Consequently, low gas velocities result in less than
optimum efficiency. However, high gas velocities can cause
collected particles to be reentrained in the gas stream, which
may result in lower overall control efficiency. Therefore, gas
velocities should be maintained high enough to optimize
collection through inertial impaction yet not cause
reentrainment.
Tests have been conducted to compare the performance of
units with vertical airflow and horizontal airflow. These tests
show that:
1. Reentrainment velocities are higher in the systems with
horizontal gas flow (i.e., vertically installed mesh pads)
because this configuration provides better drainage, and
2. When the units are operated at the same gas velocities,
there is less reentrainment in the system with horizontal gas
flow.14
4.2.2 Scrubbers
Single and double packed-bed scrubbers are the predominant
types of scrubbers used to control emissions of chromic acid mist
from chromium plating and chromic acid anodizing operations.
Other scrubber types used less frequently include fan-separator
packed-bed and centrifugal-flow scrubbers.
4-16
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4.2.2.1 Packed-Bed Scrubbers. Packed-bed scrubbers used to
control chromic acid mist are either horizontal or vertical
countercurrent-flow units equipped with one or two packed beds
followed by a chevron-blade mist eliminator. Diagrams of a
single packed-bed and a double packed-bed unit are presented in
Figures 4-8 and 4-9, respectively. Operating parameters for
typical packed-bed scrubbers are presented in Table 4-2.
Factory-assembled horizontal-flow scrubbers are available for
airflow rates ranging from 14 to 1,700 standard itr/min (500 to
60,000 standard ft3/min), and vertical-flow scrubbers are
available for airflow rates ranging from 14 to 680 m3/min (500 to
24,000 ft^/min). Control device vendors estimate that removal
efficiencies for these units range from 95 to 99 percent.1^'^
In single packed-bed units, removal of chromic acid mist
from the gas stream is accomplished by first reducing the
velocity of the gas stream to less than 150 m/min (500 ft/min) at
the scrubber inlet to maximize impingement efficiency. Water
sprayed countercurrent to the flow of the gas stream from spray
nozzles located in front of the packed-bed enlarges the mist
droplets contained in the gas stream, causing some droplets to
settle to the bottom of the scrubber by gravity. The gas stream
then passes through a packed bed. The packed bed is usually
about 30.5 cm (12 in.) thick and contains packing media that is
continuously washed with water from the spray nozzles. Chromic
acid droplets in the gas stream impinge on the packing material
and are washed to the bottom of the scrubber. In double
packed-bed units, these first two stages are repeated. In either
case, the scrubber also contains a mist elimination section
located downstream of the packed bed(s) to collect any water
carry-over. Generally, a conventional chevron-blade mist
eliminator is used.1^'17<^
The depth of the packed bed ranges from 10 to 12 times the
major dimension of the packing media. The packing media used to
control chromic acid mist typically are made of polypropylene and
have a high surface area-to-volume ratio and the capacity to
distribute, collect, and redisperse the scrubbing liquid quickly.
4-17
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The media typically are ballast rings or saddle-shaped packing
that range from 2.5 to 5.1 cm (l to 2 in.) in diameter and have a
void space of 90 to 95 percent and a surface area-to-volume ratio
ranging from 98 to 148 m2/m3 (30 to 45 ft2/ft3).19
Most units are equipped with recirculation equipment to
conserve water. The scrubbing liquid is continuously
recirculated through the scrubber either from a reservoir or sump
in the bottom of the scrubber or from a remote recirculation
tank. Typically, the chromic acid concentration in the scrubber
water is less than 7.5 g/L (1.0 oz/gal). Remote recirculation
tanks typically are used in northern climates because the tanks
can be located indoors to prevent the scrubbing liquid from
freezing during winter. Losses due to evaporation from the
scrubber are about 5 percent of the total volume of water. Some
plants use once-through water and drain the scrubbing liquid to a
wastewater treatment system. However, most plants drain the
scrubber water to the plating tanks daily to compensate for
evaporative losses from the tanks.
4.2.2.2 Fan-Separator Packed-Bed Scrubbers. A diagram of a
fan-separator packed-bed scrubber is presented in Figure 4-10,
and typical operating parameters are presented in Table 4-3. The
fan-separator packed-bed scrubber consists of two stages: a
dynamic scrubbing stage followed by an impingement stage. In the
first stage, ventilation air is ducted into the eye of a
backward-blade centrifugal fan, where it is sprayed with a small
volume of water or other scrubbing liquid under high pressure.
Contaminant aerosols are entrained and spun out centrifugally
onto the fan scroll. The centrifugal action created by the fan
wheel eliminates approximately 50 percent of the incoming chromic
acid mist. In the second stage, the exhaust gas flows into an
expansion chamber containing one or two packed beds of tubing
made of polypropylene. The expansion chamber is designed to
reduce the gas flow rate to no more than 150 m/min (500 ft/min)
for maximum impingement efficiency. The gases are sprayed with
water before the first packed bed. Because the gas flow changes
direction numerous times as it passes through the packed bed,
4-21
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chromic acid droplets impinge on the packing media. The second
packed bed is dry and acts as a mist eliminator. Contaminated
water is pumped from the unit to a recirculation tank or a
wastewater treatment system. Control efficiencies are estimated
to range from 95 to 99 percent.21
TABLE 4-3. TYPICAL OPERATING PARAMETERS FOR FAN-SEPARATOR
PACKED-BED SCRUBBERS
Pressure drop, kPa (in. w.c.)
Gas flow rate, m3/min (acfm)
Gas velocity at inlet of fan, m/min
(ft/min)
Water flow rate, L/min (gal/min)
Gas velocity across bed(s), m/min
(ft/min)
0.5 (2.0)
1.4-2,800 (50-100,000)
610-1,070 (2,000-3,500)
0.5-190 (0.1-50)
152 (500)
4.2.2.3 Factors Affecting Packed-Bed Scrubber Performance.
The primary operating parameters affecting the performance of
packed-bed scrubbers are the liquid-to-gas (L/G) ratio and the
superficial gas velocity entering the packed bed. If the L/G
ratio is too high, the packed bed will become flooded and the gas
flow will be restricted. A L/G ratio that is too low will result
in insufficient wetting of the packed bed, leaving portions of
the bed dry. This inhibits interception of particles by the
fluid boundaries on the packing material. Also, the inlet gas
stream will not be wetted enough to allow enlargement of the
chromic acid droplets. Therefore, a L/G ratio that is too low
will result in lower collection efficiencies.
Removal of chromic acid mist is accomplished by reducing the
velocity of the gas stream to less than 150 m/min (500 ft/min) to
maximize impingement. This is accomplished by an expansion
chamber at the inlet of the scrubber. However, the velocity must
be maintained at a rate such that the droplets possess sufficient
energy to collide with the packing media. Operation of packed-
bed units at greater than the design superficial gas velocity
will decrease gravitational settling of chromic acid droplets
4-23
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upstream of the packed bed. Increasing the superficial gas
velocity above optimal levels will also cause reentrainment of
chromic acid droplets from the packed bed and result in an
overall decrease in collection efficiency.
Other factors that affect the performance of a packed-bed
scrubber are the surface contact area of the packing media and
the distribution of the packing media in the packed bed. A
decrease in the surface contact area of the packing media will
result in an increase in the amount of chromic acid mist escaping
the packed bed.22 If the packing media are not uniformly
distributed in the bed, excessive channeling will occur and
decrease the efficiency of the scrubber. 2 Channeling also
occurs if the packed-bed housing becomes bowed and the packing
material settles. Numerous types of packing media are available,
and, therefore, the selection of media is based on the chemical
and physical properties of the particular gas stream being
controlled. Packing media are selected to maximize removal
efficiency for the given particle size distribution while
minimizing pressure drop.
The performance of a packed-bed scrubber can be affected by
plugging of the spray nozzles, which reduces the volume and
changes the spray pattern of the water going into the scrubber.
Another factor affecting performance is the excessive buildup of
chromic acid on the packing material that may lead to
reentrainment of the chromic acid droplets from the packed bed or
plugging of the bed.
4.2.2.4 Centrifugal-Flow Scrubbers. There are many types
of centrifugal-flow scrubbers. The configuration used to control
chromic acid mist, shown in Figure 4-11, is discussed here.
Contaminated air is drawn through the intake duct and sprayed
with clean or recirculated water. Water sprays impinge on the
high-speed blower wheel and are reduced to fog. The fog mixes
with the contaminated air and entrains the contaminants. The
blower wheel, which is located axially within the separating
chamber, also serves as the impeller of a centrifuge. The
centrifugal action separates the water-entrained contaminants
4-24
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Intake
Fumes
Water Inlet
Exhaust
»• Washed
Air
Intake Stack
Spray Chamtfer
Separating
Chamber
Blower
Drain
Outlet
Figure 4-11. Centrifugal-flow scrubber
23
4-25
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from the exhaust gas, and the contaminants and water are drained
to the bottom of the unit. The cleaned air is discharged from
the top of the unit.23 The pressure drop across the scrubber
ranges from 0.12 to 0.31 kPa (0.5 to 1.25 in. w.c.). Estimated
removal efficiencies range from 95 to 99 percent.24
4.2.2.5 Factors Affecting Centrifugal-Flow Scrubber ~ '
Performance. The primary factors affecting the performance of
centrifugal-flow scrubbers are water distribution and quality,
droplet size, and gas velocity. Uniform water distribution is
necessary for optimal scrubber performance. If the solids
content of the scrubber water is too high, wear and abrasion of
the spray nozzle tips can occur, resulting in poor spray
distribution and reduced performance of the scrubber.
If the water droplets inside the scrubber are too large,
performance also will be adversely affected because as droplet
size increases, net surface area per unit volume decreases.25
Water droplet size can increase if the header water pressure at
the spray nozzles is too low, resulting in poor atomization.
Poor atomization can also result if the solids content of the
scrubber water is allowed to increase beyond design levels.
Centrifugal-flow scrubbers must operate within specific gas
velocity limits. Low gas velocities result in inadequate
contaminant removal due to low contact/turbulence. High gas
velocities cause flooding and carry-over.25
4.2.3 Chemical Fume Suppressants
Chemical fume suppressants are surface-active compounds that
are added directly to chromium plating and chromic acid anodizing
baths to reduce or inhibit misting.
Fume suppressants are classified as temporary or as
permanent. Temporary fume suppressants are depleted primarily by
decomposition of the active chemical components, and permanent
fume suppressants are depleted by drag-out of the solution. Fume
suppressants, which are manufactured in liquid, powder, or tablet
form, include wetting agents, foam blankets, and combinations of
both wetting agents and foam blankets.
4-26
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Wetting agents are surface-active compounds that reduce or
inhibit misting by lowering the surface tension of the plating or
anodizing bath. When the surface tension of the solution is
lowered, gases escape at the surface of the plating solution with
less of a "bursting" effect, forming less mist. Fume
suppressants that produce a foam blanket do not preclude"the
formation of chromic acid mist, but rather trap the mist formed
under the blanket of foam.
Fume suppressants are used widely by decorative chromium
electroplaters. In contrast, hard chromium platers seldom use
fume suppressants. Fluorinated wetting agents have a tendency to
aggravate pitting, which affects the quality of the hard chromium
plate. Also, when foam blankets are used, there is a potential
for explosion of the entrapped hydrogen gas. These tendencies
are more pronounced in hard chromium plating than in decorative
chromium plating because of the higher current densities and
longer plating times associated with hard chromium electroplating
operations.
4.2.3.1 Wetting Agents. The most common type of wetting
agents used are fluorinated wetting agents because they are very
stable throughout a wide range of operating temperatures, current
densities, chromic acid concentrations, and oxidation-reduction
reactions. Examples of wetting agent formulations include
potassium perfluorooctane sulfonate (CgF-^SOgK) and tetraethyl-
ammonium perfluorooctane sulfonate (CgF17S03"N+(C2H5)4),2^
A number of fume suppressant formulators indicate that
wetting agents that are fluorocarbon-based may aggravate pitting
and defects in base metals when plating thickness exceeds 13 to
25 /xm (0.5 to 1 mil) . 27~29 Some fume suppressant vendor
literature recommends caution regarding use of these compounds as
the chromium thickness increases beyond 25 to 100 /xm (1 to
4 mils) (depending on the product).^ However, some
manufacturers now state that certain base metals have a tendency
to pit and that this tendency is not aggravated by the use of
fume suppressant additives. lf^2 Some fume suppressants are not
4-27
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fluorinated and are reported to be successfully used for hard
chromium plating deposits of any thickness.2**' 33
Figure 4-12(a) shows that additions of a wetting agent to a
plating bath can significantly reduce the surface tension of the
bath. Plating baths typically have a surface tension of about
70 dynes/cm (4.8 x 10"3 lbf/ft). The addition of 120 g of
wetting agent per 100 L (1.0 Ib of wetting agent per 100 gal) of
plating solution reduced the surface tension of the bath from
about 70 dynes/cm (4.8 x 10"3 lbf/ft) to about 40 dynes/cm
(2.7 x 10"3 lbf/ft).34 Further additions of the wetting agent
will lower the surface tension of the plating solution slightly;
however, a point is reached where additions of the wetting agent
will not produce a lower surface tension. As shown in
Figure 4-12(b), chromic acid emissions are significantly lower
for surface tensions below 30 to 40 dynes/cm (2.0 x 10"^ to
2.7 x 10"5 lbf/ft) than for surface tensions above these levels.
The initial makeup volume of wetting agents is determined by
the volume of plating or anodizing solution and the temperature
of the bath. Wetting agents are depleted from plating and
anodizing baths by drag-out. Monitoring the surface tension of
the plating or anodizing bath is the most effective method for
determining when to add wetting agent to the bath. The surface
tension of the bath can be determined by using a stalagmometer or
by comparing the rise in a capillary tube with a calibration
curve prepared for that purpose. Another method to determine if
an addition is needed is to hold a white piece of paper over the
bath for several minutes and observe whether spots caused by
misting appear on the paper.
4.2.3.2 Foam Blankets. Foam blankets are usually 1.3 to
2.5 cm (0.5 to 1.0 in.) thick and cover the entire surface of the
plating bath. The foam blanket is formed by agitation produced
by the hydrogen and oxygen gas bubbles generated during plating.
Foam blankets entrap the hydrogen gas and chromic acid mist
in the foam layer. If a heavy layer of foam (thickness greater
than 2.5 cm [1.0 in.]) is present, the hydrogen gases will build
up in the foam layer, and if a spark is generated (e.g., from the
4-28
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Cone, of wetting agent (lb/100 gal)
(a) Wetting agent concentration vs. surface tension
of chromic acid.
55°C(131°F)
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Surface Tension (dynes/cm)
(b) Surface tension vs. chromic acid emissions,
Figure 4-12. Effect of wetting, agent on chromic acid
emissions.
4-29
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contacting equipment) a hydrogen explosion can occur. As a
result of this minor explosion, the foam layer along with a
portion of the plating solution is blown out of the tank and the
chromium plate on the part could be damaged. However, if the
foam layer is not maintained at a minimum reasonable thickness,
the ability of the foam layer to inhibit misting is reduced."
Initial makeup volumes of foam blanket solutions are
determined by the surface area of the solution, amount of current
applied, and temperature and chromic acid concentration of the
plating bath. Generally, the lower the temperature, the less
product is needed. Foam blankets are depleted primarily by
decomposition; however, drag-out of the foam may also be a
factor. Also, foam blankets may be pulled into ventilation hoods
if the solution level is too close to the hoods. Some types may
also be depleted by excessive air agitation of the bath.
Appreciable concentrations of alkali metal ions, especially
potassium, tend to reduce the solubility of some foam blankets.
Visual monitoring of the thickness of the foam blanket is the
most common method for determining when to add foam blanket
solution to the bath. The frequency of the maintenance additions
depends on the amount of work processed through the plating tank
and the drag-out rate of the solution.
4.2.3.3 Combination Wetting Agent/Foam Blanket.
Combination fume suppressants (wetting agent plus a foam blanket)
reduce the surface tension of the plating bath while forming a
foam blanket over the surface. Because of the synergistic
effects of the two components, less product is required than if
either the wetting agent or the foam blanket were used alone.
4.2.3.4 Factors Affecting Performance. The main factor
affecting the performance of chemical fume suppressants is the
amount of fume suppressant present in the plating or anodizing
bath. If insufficient wetting agent is present in the bath, the
surface tension of the solution will not be reduced below
40 dynes/cm (2.7 x 10"3 lbf/ft), and, therefore, the
effectiveness of the wetting agent in inhibiting misting will be
substantially reduced. If a foam blanket is used, proper care
4-30
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must be taken to maintain the foam blanket at the specified
thickness because a thin foam layer will not entrap the chromic
acid mist efficiently, and a heavy foam blanket may cause a
hydrogen gas buildup and explosion potential.
4.2.4 Plastic Balls
4.2.4.1 Description. Floating polypropylene balls-~are
often used in plating baths to reduce heat loss, evaporation, and
(to a limited extent) misting. The balls are approximately
3.2 cm (1.25 in.) in diameter and are typically recommended to be
two layers deep across the surface of the plating solution.
4.2.4.2 Factors Affecting Performance. Polypropylene balls
are generally used on hard chromium plating baths to reduce
evaporation of plating solution and inhibit misting. They are
generally not used in automated plating or anodizing operations
because plating racks drag the balls out of the baths. The balls
tend to be pushed away from the anodes and cathodes where the
surface of the bath is agitated by gassing, thus reducing their
effectiveness for inhibiting misting.
4.2.5 Moisture Extractors
Moisture extractors are often used preceding or following
the principal air pollution control device. Moisture removal is
accomplished centrifugally as the air passes through a set of
stationary blades. A moisture extractor used prior to a control
device reduces the inlet loading on the primary control unit.
Moisture extractors are commonly used prior to a mesh-pad mist
eliminator to help reduce plugging. When the device is used
following the primary control device, its function is to minimize
reentrainment or carry-over from the primary control device if
the primary device malfunctions or is operated improperly.
4.3 PERFORMANCE CAPABILITIES OF CONTROL TECHNIQUES FOR CHROMIUM
EMISSIONS
Based on evaluations of information obtained from the
literature, contacts with air pollution control device vendors,
and site visits to electroplating facilities, applicable
alternative air pollution control techniques were identified. An
emissions test program was designed to evaluate the performances
4-31
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of the techniques determined to be most representative of those
applied in the industry.
The results of 10 EPA-conducted emissions tests are
summarized in Tables 4-4a and 4-4b. Facilities selected for
emission testing were representative of typical hard and
decorative chromium plating shops based on the size of the
plating tanks, the types of parts plated, and the plating bath
operating parameters. The operating parameters examined at each
facility were the current, voltage, plating time, temperatures,
and chromic acid concentration of the plating bath. The air
pollution control devices tested include six mist eliminators and
three packed-bed scrubbers. Emissions tests were conducted at
the inlet and outlet of each control device to characterize
uncontrolled emissions and the performance of the control device.
A summary and discussion of the emissions test results for hard
chromium electroplating are presented in Section 4.3.1. In
addition, EPA also conducted a test on a decorative chromium
plating operation to evaluate the performance of fume
suppressants. The fume suppressant test data are summarized and
discussed in Section 4.3.2. A summary discussion of the
emissions test results and conclusions regarding performance are
presented in Section 4.3.3. Complete information about each test
is presented in Appendix C ("Summary of Test Data"), and the
testing and analysis methodologies are described in Appendix D
("Emission Measurements") of this document.
During the early part of the test program, both hexavalent
and total chromium were measured at each site (Plants A, B, D, I,
and K). The results of these tests indicate that, considering
the precision of the sampling and analytical methods used, the
hexavalent and total chromium levels were essentially the same
(varying within ±10 percent in most instances). Therefore,
essentially all the chromium was in the hexavalent form, which
would be expected, given the fact that chromic acid is a
hexavalent compound of chromium. For these reasons, and for
reasons discussed in Appendix D, total chromium analyses were
discontinued for the remainder of the plants tested. 'The
4-32
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TABLE 4-4a.
SUMMARY OF EMISSION TEST RESULTS FOR HEXAVALENT
CHROMIUM
(Metric Units)a
Outlet
Control process rate,
Plant device Ah
Hexavalent chromium m»ss
emission, kg/hr xlO
Inlet
Outlet
Hexavalent chromium
Range of emission concentration,
control device mg/dscm x 10 '3
efficiencies,
percent
Inlet
Outlet
Hexavalent chromium
emissions per process
rate, mg/Ah
Inlet
Outlet
Chevron-blade mist eliminators
A b
B c
D d
Mesh-pad mist eliminators
Ee f
F g
0 g
Packed-bed scrubbers
I h
K i
l) h
L> h
L1 h
Polypropylene balls
Gm n
Fume suppressant
N o
N P
13,100
14,400
19,900
12,100
12,200
8,800
8,150
8,750
5,300
7,200
7,800
7,800
8,500
10,500
26
15
76
31
83
24
90
46
23
22
24
22
3.6
3.6
3.3
1.3
1.2
0.4
0.23
0.27
0.52
1.5
1.2
0.71
0.65
5.4
0.02
0.01
83.1-91.0
86.9-95.1
98.0-98.7
98.4-99.0
99.2-99.9
98.7-99.0
99.1-99.6
94.9-98.1
94.3-95.1
96.3-97.2
97.2-97.3
68.0-81.9
99.3-99.6
99.7-99.9
2,030
1,760
7,960
3,070
11,400
4,410
5,510
1,670
715
668
723
3,980
921
921
310
150
120
40
33
43
30
52
39
23
21
960
4.7
2.2
4.5
3.2
9.2
6.2
16.0
6.6
23.0
16.0
9.0
6.0
8.0
7.2
1.4
1.4
0.59
0.27
0.14
0.08
0.04
0.07
_ 0.14
0.56
0.45
0.20
0.22
1.8
0.007
0.003
*A11 tests were conducted by EPA.
"Chevron-blade mist eliminator with a single set of sinusoidal wave-type blades.
cChevron-blade mist eliminator with a single set of overlapping-type blades.
"Chevron-blade mist eliminator with a double let of overlapping-type blade*.
'Moisture extractor preceded mist eliminator. Tests were conducted at the inlet to the moisture extractor and the outlet of the mist
eliminator. Combined efficiencies are presented here.
'Mist eliminator containing a double set of overlapping-type chevron blades followed by two mesh pads in series.
^Double mesh-pad mist eliminator.
I'Single packed-bed, horizontal-flow wet scrubber.
'Double packed-bed, horizontal-flow wet »crubber.
•INo overhead washdown of the scrubber packing.
''Periodic overhead washdown of the scrubber packing.
Continuous overhead washdown of the scrubber packing.
""Tests were conducted at the mist eliminator inlet with and without polypropylene balls.
"Polypropylene balls 3.8 cm in diameter with two to three layers of coverage.
°Foam blanket.
P Wetting agent in combination with a foam blanket.
4-33
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TABLE 4-4b.
SUMMARY OF EMISSION TEST RESULTS FOR HEXAVALENT
CHROMIUM
(English Units)a
Outlet
Control process rate,
Plant device Ah
Hexavalent chromium mass
emission, Ib/hr x 10"^
Inlet
Outlet
Range of
control device
efficiencies,
percent
Hexavalent chromium
emission concentration,
gr/dscfxlCT3
Inlet
Outlet
Hexavalent chromium
emissions per process
rate, gr/Ah
Inlet Outlet
Chevron-bUde mist eliminators
A b
B c
D d
13,100
14,400
19,900
57
33
170
7.3
2.9
2.7
83.1-91.0
86.9-95.1
98.0-98.7
0.89
0.77
3.5
0.13
0.07
0.05
0.07
0.05
0.14
0.009
0.004
0.002
Mesh-p«d mitt eliminators
Ee f
F g
G g
Packed-bed scrubbers
1 h
K i
LJ h
Lk h
L1 h
Polypropylene balls
Gm n
Fume suppressant
N o
N p
12,100
12,200
8,800
8,150
8,750
5,300
7,200
7,800
7,800
8,500
10,500
69
180
53
200
100
51
48
52
48
7.9
7.9
0.93
0.51
0.59
1.2
3.4
2.6
1.6
1.4
12
0.04
0.02
98.4-99.0
99.2-99.9
98.7-99.0
99.1-99.6
94.9-98.1
94.3-95.1
96.3-97.2
97.2-97.3
680-81.9
99.3-99.6
99.7-99.9
1.3
5.0
1.9
2.4
0.73
0.31
0.29
0.32
1.7
0.40
0.40
0.02
0.01
0.02
0.01
0.02
0.02
0.01
0.01
0.42
0.002
0.001
0.10
0.25
0.10
0.35
0.24
0.14
0.09
0.12
0.11
0.02
0.02
0.001
0.001
4.001
0.002
0.009
0.007
0.003
0.003
0028
0.00010
0.00005
*A11 tests were conducted by EPA.
Chevron-blade mist eliminator with a single set of sinusoidal wave-type blades.
cChevron-blade mist eliminator with a single set of overlapping-typeblades.
''Chevron-blade mist eliminator with a double set of overUpping-type blades.
Moisture extractor preceded mist eliminator. Tests were conducted at the inlet to the moisture extractor and the outlet of the mist
eliminator. Combined efficiencies are presented here.
Mist eliminator containing a double set of overlapping-type chevron blades followed by two mesh pads in series.
^Double mesh-pad mist eliminator.
Single packed-bed, horizonul-flow wet scrubber.
'Double packed-bed, horizonul-flow wet scrubber.
JNo overhead washdown of the scrubber packing.
Periodic overhead washdown of the scrubber packing.
'Continuous overhead washdown of the scrubber packing
"Tests were conducted at the mist eliminator inlet with and without polypropylene balls.
"Polypropylene balls 3.8 cm (1.5 in.) in diameter with two to three layers of coverage.
°Foam blanket.
P Wetting agent in combination with a foam blanket.
4-34
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following discussions of emissions test results address emissions
in terms of hexavalent chromium.
4.3.1 Tests at Hard Chromium Electroplating Operations
4.3.1.1 Chevron-Blade Mist Eliminator Tests.
4.3.1.1.1 Plant A. Plant A is a medium-size job shop that
performs hard chromium electroplating of textile, hydrauITc,
woodworking, and laundry machine parts. The hard chromium
plating facility consists of six tanks. Tests were conducted
across a mist eliminator on Tank 6, which is 6.4 m (21 ft) long,
0.9 m (3 ft) wide, and 1.8 m (6 ft) deep and has a capacity of
9,800 L (2,590 gal). The tank is equipped with a
transformer/rectifier rated at 8 to 10 V and 5,000 to 8,000 A.
The tank is laterally exhausted. The plating bath is a
conventional hard chromium plating solution containing about
255 g/L (34 oz/gal) of chromic acid and 2.55 g/L (0.34 oz/gal) of
sulfuric acid catalyst. The bath normally operates at 50° to
60°C (120° to 140°F).35
Emissions that are captured by the exhaust system are vented
to a chevron-blade mist eliminator with a single set of
sinusoidal wave-type blades. The blades are approximately 1.2 m
(4.0 ft) in height, cover an area of about 1.2 m (4.0 ft) in
width, and extend 0.2 m (0.8 ft) back into the unit. The mist
eliminator was installed in 1980. The design parameters of the
mist eliminator include a gas flow rate of 280 standard m3/min
(10,000 standard ft3/min), cross-sectional velocity of 270 m/min
(900 ft/min), and a pressure drop of 0.19 kPa (0.75 in. w.c.).
During emissions testing, the actual gas flow rate to the mist
eliminator was 230 m3/min (7,970 ft3/min).36 The mist eliminator
contains 31 chevron blades spaced 3.2 cm (1.3 in.) apart. The
blades are arranged to change the direction of the gas flow four
times at 30° angles. The mist eliminator is periodically washed
with water, which then drains into the plating tank. During
testing, the mist eliminator was washed down after each test run.
Four test runs were conducted by EPA at the inlet and outlet
of the mist eliminator on Tank 6. The results are summarized in
Table 4-5. Uncontrolled emissions measured at the inlet averaged
4-35
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2.0 mg/dscm (0.89 x 10"3 gr/dscf), or 26 x 10"3 kg/hr
(57 x 10 ~3 Ib/hr). Emissions measured at the outlet averaged
0.31 mg/dscm (0.13 x 10~3 gr/dscf), or 3.3 x 10~3 kg/hr
(7.3 x 10"3 Ib/hr). The removal efficiency of the mist
eliminator ranged from 83.1 to 91.0 percent. The average total
current applied to the system during outlet testing was
13,100 Ah. Therefore, the hexavalent chromium process emission
rate from the mist eliminator was 0.59 mg/Ah (0.009 gr/Ah).
TABLE 4-5. PERFORMANCE DATA FOR PLANT A37
Run No. mg/dscm
1 1.52
2 2.45
3 1.55
4 2.59
AVG 2.03
Inlet
kg/hr (10'3)
20.3
31.2
20.0
32.3
26.0
mg/Ah
3.44
6.00
2.52
6.09
4.51
Outlet
mg/dscm kg/hr (10~3)
0.168
0.377
0.173
0.507
0.306
1.83
4.15
1.87
5.45
3.32
mg/Ah
0.296
0.804
0.236
1.04
0.594
Efficiency,
percent*
91.0
86.7
90.7
83.1
87.9
Efficiencies are calculated from mass emission rates, and the average is based on averaging efficiencies for
each run.
4.3.1.1.2 Plant B. Plant B manufactures and refurbishes
industrial rolls for the packaging and textile industries. The
plant operates six hard chromium plating tanks. Emissions tests
were conducted across a chevron-blade mist eliminator with a
single set of overlapping-type blades that treats ventilation air
from two of the hard chromium plating tanks.
Tank 1 is 1.5 m (5.0 ft) long, 0.7 m (2.3 ft) wide, and
1.8 m (6.0 ft) deep and holds about 1,780 L (470 gal) of plating
solution. Tank 2 is 1.8 m (6.0 ft) long, 0.8 m (2.5 ft) wide,
and 1.8 m (6.0 ft) deep.and holds about 2,350 L (620 gal) of
plating solution. The chromic acid concentration of the plating
baths is 210 g/L (28 oz/gal) of solution. The normal operating
temperature of the plating baths ranges from 43°C (110°F) to 54°C
4-36
-------
(130°F). Both tanks are equipped with a circulating water
cooling system.38
Tank 1 contains two work stations, each of which is equipped
with a 3,000-A rectifier. Tank 2 is equipped with one 5,000-A
rectifier. The operating voltage and current for each roll
plated typically ranges from 10 to 15 V and 1,200 to 1,60TTA,
respectively. About 13 pm (0.5 mil) of chromium plate is applied
to each roll.
Both tanks are equipped with double-sided lateral exhaust
hoods. Exhaust gases from both tanks are ducted together and
vented to a horizontal-flow chevron-blade mist eliminator that
was installed in 1987. The mist eliminator contains a single set
of overlapping-type blades. The blades are approximately l.l m
(3.5 ft) in height, cover an area of about 1.0 m (3.3 ft) in
width, and extend 0.2 m (0.8 ft) back into the unit. The blades
are spaced about 3.2 cm (1.3 in.) apart. The mist eliminator was
designed to treat 230 standard m3/min (8,000 standard ft3/min) of
gas at a pressure drop of 0.19 kPa (0.75 in. w.c.). During
emissions testing, the actual gas flow rate at the inlet was
150 m3/min (5,390 ft3/min).
A moisture extractor is installed in the stack to control
chromium emissions that may be drawn through the mist eliminator.
The mist eliminator and moisture extractor are equipped with a
spray washdown system. The wash water is drained initially into
a 340-L (90-gal) holding tank and then, as needed, into the
plating tanks as makeup for plating solution evaporation losses.
The mist eliminator and moisture extractor are washed one or two
times a day depending on the amount of plating solution makeup
needed. During the emissions testing period, the mist eliminator
was washed each morning (prior to testing) with about 230 L
(60 gal) of water.
Three test runs were conducted by EPA at the inlet and
outlet of the mist eliminator. The test results are summarized
in Table 4-6. Uncontrolled emissions measured at the inlet
averaged 1.8 mg/dscm (0.77 x 10"3 gr/dscf), or 15 x 10"3 kg/hr
(33 x 10"3 Ib/hr). Emissions measured at the outlet averaged
4-37
-------
0.15 mg/dscm (0.07 x 10"3 gr/dscf), or 1.3 x 10~3 kg/hr
(2.9 x 10~3 Ib/hr). The corresponding removal efficiency ranged
from 86.9 to 95.1 percent. The average total current applied
during outlet testing was 14,400 Ah. Therefore, the hexavalent
chromium process emission rate from the mist eliminator was
0.27 mg/Ah (0.004 gr/Ah).
TABLE 4-6. PERFORMANCE DATA FOR PLANT B39
Run No.
1
2
3
AVG
mg/dscm
1.81
1.74
1.74
1.76
Inlet
kg/hr (10'3)
15.5
14.8
15.2
15.2
mg/Ah
3.10
3.15
3.23
3.16
mg/dscm
0.089
0.224
0.135
0.149
Outlet
kg/hr (lO'3)
0.76
1.94
1.21
1.30
mg/Ah
0.150
0.410
0.257
0.272
Efficiency,
percent*
95.1
86.9
92.0
91.3
Efficiencies are calculated from mass emission rates, and the average is based on averaging efficiencies for
each run.
4.3.1.1.3 Plant D. Plant D is a small-size job shop that
performs hard chromium electroplating of industrial rolls. The
plant operates two plating tanks. Tests were conducted across
the mist eliminator that controls emissions from one of the
tanks. The tank is 4.3 m (14.0 ft) long, 1.2 m (4.0 ft) wide,
and 3.0 m (10.0 ft) deep and holds about 15,100 L (3,980 gal) of
plating solution. The plating bath consisted of a conventional
hard chromium plating solution containing about 210 g/L
(28 oz/gal) of chromic acid and 1.3 g/L (0.18 oz/gal) of sulfuric
acid. The normal operating temperature of the plating bath
ranges from 43° to 60°C (110° to 140°F). The tank is cooled with
circulating water. The tank is equipped with a transformer/
rectifier rated at 12 V and 12,000 A.40
The plating tank is equipped with a push-pull capture system
and a chevron-blade mist eliminator, both of which were installed
in July 1985. The mist eliminator contains two sets of
overlapping-type chevron blades. The blades are approximately
1.0 m (3.1 ft) in height, cover an area of about 0.9 m (3.0 ft)
4-38
-------
in width, and each set of blades extends 0.2 m (0.8 ft) back into
the unit. The design face velocity through the mist eliminator
is 190 m/min (630 ft/min) at a pressure drop of 0.5 kPa
(2.0 in. w.c.). The pressure drop was not monitored during
testing; however, there were no indications of any malfunctions
in the mist eliminator or capture system. The system was"'
designed to treat 170 standard m3/min (6,000 standard ft3/min).
During testing, the gas flow rate measured at the inlet of the
mist eliminator averaged 180 actual m3/min (6,260 actual
ft3/min). A moisture extractor is installed in the stack
downstream of the mist eliminator.41 The mist eliminator and
moisture extractor are washed with an average of 280 L (75 gal)
of water at the end of each work day and at the beginning of~each
work day if the tank is operated overnight. During testing, the
mist eliminator and moisture extractor were washed with about
320 L (85 gal) of water after the first test run and with about
250 L (70 gal) of water after the third test run.
Three test runs were conducted at the inlet and outlet of
the mist eliminator. Testing at the inlet and outlet was
performed simultaneously. Test results are presented in
Table 4-7. Emissions measured at the inlet averaged 8.0 mg/dscm
(3.5 x 10"3 gr/dscf), or 76 x 10"3 kg/hr (170 x 10'3 Ib/hr).
Outlet emissions averaged 0.12 mg/dscm (0.05 x 10"3 gr/dscf), or
1.2 x 10"3 kg/hr (2.7 x 10'3 Ib/hr). The control efficiency
across the mist eliminator ranged from 98.0 to 98.7 percent. The
average total current applied during outlet testing was about
19,900 Ah. Therefore, the hexavalent chromium process emission
rate from the mist eliminator was 0.14 mg/Ah (0.002 gr/Ah).
4-39
-------
TABLE 4-7. PERFORMANCE DATA FOR PLANT D42
RUD No.
1
2
3
AVG
mg/dscm
10.20
6.85
6.83
7.96
Inlet
kg/hr (lO'3)
95.4
68.1
65.2
76.2
ing/ Ah
11.1
7.24
9.18
9.17
mg/dscm
0.130
0.140
0.102
0.124
Outlet
kg/hr (10'3)
1.26
1.36
0.99
1.20
mg/Ah
0.147
0.140
0.134
0.140
Efficiency,
percent*
98.7
"""' 98.0
98.5
98.4
Efficiencies are calculated from mass emission rates, and the average is based on averaging efficiencies for
each run.
4.3.1.2 Discussion of Chevron-Blade Mist Eliminator
Performance Data. Table 4-8 presents the performance data for
Plants A, B, and D. The mist eliminator in Plant A contained a
single set of wave-type blades. Plant B's mist eliminator
contained a single set of overlapping-type blades, and Plant D's
unit had a double set of overlapping-type blades. A graphic
presentation of the -outlet concentrations for each plant is
presented in Figure 4-13. Based on a comparison of average
outlet concentrations for Plants A and B, it appears that the
overlapping blade design may be more effective than the
sinusoidal wave-type blade design. (Outlet concentrations ranged
from 0.168 to 0.507 mg/dscm (7.4 x 10~5 to 2.2 x 10"4 gr/dscf)
for Plant A and 0.089 to 0^224 mg/dscm (3.9 x 10"5 to
9.8 x 10"5 gr/dscf) for Plant B, so there is a small amount of
data overlap.) As shown in Table 4-8, inlet loadings were very
similar for Plants A and B. Therefore, the slightly lower
average outlet process emission rate and the 3 percent higher
average efficiency for Plant B also suggest that the overlapping
blade design may be superior to the wave-type design.
There is no significant difference between the average
outlet concentrations for Plants B and D, and as illustrated in
Figure 4-13, there is some overlap of the data. This overlap
indicates that the second set of overlapping blades may represent
redundant control. The lower average outlet process emission
rate for Plant D is a reflection of the higher inlet loading.
4-40
-------
TABLE 4-8. PERFORMANCE DATA FOR CHEVRON-BLADE MIST
ELIMINATORS--PLANTS A, B, AND D (AVERAGES)
Concentration,
Plant inlet
A. 2.03
B 1.76
D 7.96
mg/dscm
Outlet
0.306
0.149
0.124
Outlet
nTorifie!^
emission
rates , mg/Ah
0.59
0.27
0.14
Efficiency,
percent
87-r9
91.3
98.4
CUTLET CONCENTRATION. UG/OSCU
0 6
0.5
0.4
O.J
02
-
-
-
I
n
R n
0 1 \- U
1
1
PUNT NAME
Figure 4-13. Outlet concentration data for chevron-blade
mist eliminators.
This higher inlet loading also accounts for the average
efficiency of the unit at Plant D being 7 percent higher than
that at Plant B. Percent efficiency is always dependent upon
inlet concentrations and can be used as a means to compare
performance only when there is not a significant variation in the
inlet loadings. Therefore, it cannot be concluded that the
double set of blades results in better performance for chevron-
blade mist eliminators.
4-41
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4.3.1.3 Mesh-Pad Mist Eliminator Tests.
4.3.1.3.1 Plant E. Plant E is a job shop specializing in
precision finishing and refinishing of industrial rolls. There
are seven hard chromium plating tanks at the facility. Tests
were conducted across the mist eliminator that controls emissions
from the tank designated as No. 6. The tank is 3.7 m (12.-0~"ft)
long, 0.91 m (3.0 ft) wide, and 2.9 m (9.6 ft) deep and holds
approximately 9,270 L (2,450 gal) of plating solution. The
plating solution contains chromic acid in a bath concentration of
250 g/L (33 oz/gal). Sulfuric acid is used as a catalyst at a
bath concentration of 2.5 g/L (0.33 oz/gal). The temperature of
the plating solution is maintained between 57° and 60°C (135° and
140°F). The typical current and voltage applied to Tank 6 is
8,000 A and 12 V.43
The capture and control system on Tank 6 consists of a
double-sided lateral hood ducted to a 56-cm (22-in.)-diameter
moisture extractor followed by a mist eliminator unit containing
two sets of overlapping-type blades and two mesh pads. The mist
eliminator blades are approximately 1.3 m (4.4 ft) in height and
cover an area of about 1.2 m (4.0 ft) in width, and each set of
blades extends 0.2 m (0.8 ft) back into the unit. The mist
eliminator unit was installed in June 1988.
The mist eliminator system has a design airflow rate of
280 standard m3/min (10,000 standard ft3/min) and a design
pressure drop of 0.62 kPa (2.5 in. w.c.) at a velocity of
140 m/min (450 ft/min).44 The blade section consists of two sets
of overlapping-type blades. Two sets of spray nozzles (three
nozzles per set) are located in front of each set of blades to
provide periodic washdown of the blades. The mesh pad section
consists of two pads in series. Each pad is about 1.4 m (4.5 ft)
high, 1.5 m (4.8 ft) wide, and 0.15 m (0.5 ft) deep and consists
of eight layers of mesh. The layers consist of interlocked
polypropylene filaments 0.094 cm (0.037 in.) in diameter. The
first two layers of each pad have a void space of 97 percent, and
the remaining six layers have a void space of 94 percent. During
testing, the airflow rate at the outlet of the mist eliminator
4-42
-------
unit averaged 195 m3/min (6,880 ft3/min), and the pressure drop
was measured at 0.84 kPa (3.4 in. of w.c.).
Three mass emissions tests were conducted at each of the
following locations: (l) upstream of the moisture extractor,
(2) between the moisture extractor and the mist eliminator (blade
and pad) unit, and (3) at the outlet of the mist eliminator unit.
The test results are summarized in Table 4-9. Emissions measured
at the inlet to the moisture extractor averaged 3.1 mg/dscm
(1.3 x 10"3 gr/dscf), or 31 x 10'3 kg/hr (69 x 10'3 Ib/hr).
Emissions measured at the mist eliminator outlet averaged
0.04 mg/dscm (0.02 x 10"3 gr/dscf), or 0.40 x 10"3 kg/hr
(0.93 x 10"3 Ib/hr).
TABLE 4-9. PERFORMANCE DATA FOR PLANT E45
Run No.
1
2
3
AVG
mg/dscm
2.84
3.32
3.06
3.07
Inlet
kg/hr CIO'3)
30.0
33.0
31.0
31.3
mg/Ah
6.24
6.35
5.96
6.18
mg/dscm
0.030
0.043
0.047
0.040
Outlet
kg/hr (10'3)
0.30
0.40
0.50
0.40
mg/Ah
0.062
0.077
0.096
0.078
Efficiency,
percent*
99.0
98.8
98.4
98.7
Efficiencies are calculated from mass emission rates, and the average is based on averaging efficiencies for
each run.
The combined removal efficiencies of the moisture extractor
and the mist eliminator ranged from 98.4 to 99.0 percent and
averaged 98.7 percent. This combined efficiency is regarded as
being representative of the performance of the mist eliminator
unit alone because moisture extractors are designed for the
removal of large droplets that would also be collected in the
first stage of the mist eliminator unit.
The average total current applied to the system during
outlet testing was 12,100 Ah. Therefore, the hexavalent chromium
emission rate from the mist eliminator unit was 0.08 mg/Ah
(0.001 gr/Ah).
4-43
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4.3.1.3.2 Plant F. Plant F is a small job shop
specializing in precision finishing of hydraulic cylinders. The
plant currently operates one hard chromium plating tank. The
plating tank is 2.4 m (8.0 ft) long, 0.76 m (2.5 ft) wide, and
2.7 m (9.0 ft) deep and holds approximately 4,810 L (1,270 gal)
of plating solution. The plating solution contains chromic acid
in a concentration of about 210 g/L (28 oz/gal) of water.
Sulfuric acid is used as a catalyst at a bath concentration of
2.1 g/L (0.28 oz/gal). The temperature of the plating solution
is maintained at about 54°C (130°F). The tank is divided into
two cells; each plating cell is equipped with a rectifier. The
typical current and voltage applied to each cell ranges from
2,500 to 3,000 A and from 4.5 to 6.0 V, respectively.46
The capture and control system on the plating tank consists
of a single-sided lateral hood ducted to a mist eliminator with
two mesh pads in series. The design airflow rate of the
ventilation system is 140 standard m3/min (5,100 standard
ft3/min). The actual measured flow rate during testing was
125 m3/min (4,430 ft3/min). The mesh-pad mist eliminator was
installed in May 1988. The unit has a design pressure drop of
0.62 kPa (2.5 in. w.c.) at a velocity of 150 to 210 m/min (500 to
700 ft/min).47 The pressure drop recorded during testing was
0.62 kPa (2.5 in. w.c.).
The mist eliminator consists of two mesh pads spaced
approximately 10 cm (4 in.) apart. Each mesh pad is 79 cm
(31 in.) in diameter. The primary mesh pad at the inlet of the
unit is 6.4 to 7.6 cm (2.5 to 3.0 in.) thick, and the secondary
mesh pad is 3.2 to 3.8 cm (1.25 to 1.5 in.) thick. Each pad
consists of layers of interlocked polypropylene filaments
0.051 cm (0.020 in.) in diameter. The thread count is 4.3 by
3.3 per cm2 (28 by 21 per in.2) and the weave type is honeycomb.
The unit is equipped with two spray nozzles that are activated
periodically to wash down the pads. One nozzle is located at the
inlet and sprays onto the primary mesh pad in the direction of
the airflow. The second nozzle, located at the outlet of the
unit behind the secondary pad, sprays onto the secondary mesh pad
4-44
-------
countercurrent to the airflow. At the end of each day, the
ventilation system is shut off and the spray nozzles are
activated to wash down the mesh pads. During each washdown, the
pads are flooded with 38 L (10 gal) of water at a pressure of 1.7
to 2.0 atm (20 to 30 psi). Once each month, the mesh pads are
removed and cleaned by immersion in the plating bath foltowed by
water rinsing. The mesh pads were cleaned by immersion prior to
the first test run. The mist eliminator washdown system was
activated prior to the second test run. The mesh pads were
removed and washed down with water prior to test run No. 4.
Five tests were conducted at the inlet and outlet of the
mist eliminator unit. Inlet and outlet testing was performed
simultaneously. The test results are summarized in Table 4-10.
Emissions measured at the inlet averaged 11.4 mg/dscm
(4.98 x 10'3 gr/dscf), or 83 x 10'3 kg/hr (180 x 10"3 Ib/hr).
Emissions measured at the outlet averaged 0.03 mg/dscm
(0.01 x 10"3 gr/dscf), or 0.23 x 10'3 kg/hr (0.51 x 10"3 Ib/hr).
Removal efficiencies ranged from 99.2 to 99.9 percent and
averaged 99.7 percent. The average total current applied during
outlet testing was 12,200 Ah. Therefore, the hexavalent chromium
process emission rate from the mist eliminator unit was
0.04 mg/Ah (0.001 gr/Ah).
TABLE 4-10. PERFORMANCE DATA FOR PLANT F
48
Run No,
1
2
3
4
5
AVG
mg/dscm
7.25
10,45
12.01
13.93
13.36
11.40
Inlet
kg/hr (10'3)
51.3
78.6
85.6
103.0
96.1
82.9
mg/Ah
7.78
15.7
16.5
21.5
19.8
16.3
Outlet
mg/dscm kg/hr (10~3)
0.059
0.032
0.034
0.028
0.011
0.033
0.41
0.23
0.24
0.20
0.07
0.23
mg/Ah
0.062
0.046
0.046
0.042
0.014
0.042
Efficiency,
percent*
99.2
99.7
99.7
99.8
99.9
99.7
Efficiencies are calculated from mass emission rates, and the average is based on averaging efficiencies for
each run.
4-45
-------
4.3.1.3.3 Plant G. Plant G is a job shop that plates
industrial rolls, hydraulic components, dies, and molds. The
plant operates one hard chromium plating tank. The tank is 1.8 m
(6.0 ft) long, 0.76 m (2.5 ft) wide, and 4.3 m (14.0 ft) deep and
holds approximately 5,720 L (1,510 gal) of plating solution. The
plating solution contains chromic acid in a concentration of
about 210 g/L (28 oz/gal) of water. Sulfuric acid is used as a
catalyst at a bath concentration of 2.1 g/L (0.28 oz/gal). The
plating tank is equipped with an air agitation system to maintain
uniform bath temperature and chromic acid concentration. The
temperature of the plating solution is maintained between 54° and
60°C (130° and 140°F). The maximum current and voltage of the
rectifier is 8,000 A and 9 V.49
The capture and control system on the plating tank consists
of a single-sided lateral hood ducted to a mesh-pad mist
eliminator that was installed in 1988. The design airflow rate
of the ventilation system is 110 standard m3/min (3,800 standard
ft3/min). During testing, the actual gas flow rate off the
plating tank ranged from 92 to 98 m3/min (3,240 to
3,460 ft3/min).
The mist eliminator consists of two mesh pads spaced
approximately 10 cm (4 in.) apart. Each mesh pad is 79 cm
(31 in.) in diameter. The primary mesh pad at the inlet of the
unit is 6.4 to 7.6 cm (2.5 to 3.0 in.) thick, and the secondary
mesh pad is 3.2 to 3.8 cm (1.25 to 1.5 in.) thick. Each pad
consists of interlocked polypropylene filaments 0.051 cm
(0.020 in.) in diameter. The thread count is 4.3 by 3.3 per cm2
(28 by 21 per in.2) and the weave type is honeycomb. The mist
eliminator has a design pressure drop of 0.62 kPa (2.5 in. w.c.)
at a gas velocity of 150 to 210 m/min (500 to 700 ft/min).50 The
mist eliminator unit is equipped with two spray nozzles to clean
the pads. One nozzle is located at the inlet and sprays rinse
water (from the first rinse tank following the plating tank) onto
the first mesh pad in the direction of the airflow. The second
nozzle, located behind the second mesh pad, sprays clean tap
water onto the pad countercurrent to the airflow. At the end of
4-46
-------
each day, the ventilation system is shut off and the spray
nozzles are activated for about 30 seconds to wash down the mesh
pads. Once each month, the mesh pads are removed and cleaned by
immersion in the plating bath followed by water rinsing.
Five test runs were conducted at the inlet and outlet of the
mist eliminator. During this source test program, the plating
tank was operated with and without polypropylene balls on the
surface of the plating solution. The first three test runs were
conducted without polypropylene balls to determine the
effectiveness of the mesh-pad mist eliminator under maximum
loading and to establish a baseline (i.e., without balls)
condition. The two subsequent test runs were conducted while the
balls covered the surface of the plating bath to evaluate the
effectiveness of an overlay of balls in inhibiting chromic acid
misting. The ball cover was complete, consisting of two to three
layers in most places. In typical industrial applications, the
ball cover is not usually as complete as that tested.
Emissions test results are presented in Table 4-11.
Emissions measured at the inlet to the mist eliminator, when no
polypropylene balls were being used, averaged 4.4 mg/dscm
(1.9 x 10~3 gr/dscf), or 24 x 10"3 kg/hr (53 x 10"3 Ib/hr);
outlet emissions averaged 0.04 mg/dscm (0.02 x 10"3 gr/dscf), or
0.27 x 10"3 kg/hr (0.59 x 10"3 Ib/hr). The control efficiency of
the mist eliminator unit ranged from 98.7 to 99.0 percent and
averaged 98.9 percent. The average total current applied during
outlet testing was 8,800 Ah. Therefore, the hexavalent chromium
process emission rate from the mist eliminator unit was
0.07 mg/Ah (0.001 gr/Ah).
4-47
-------
TABLE 4-11. PERFORMANCE DATA FOR PLANT G51
Run No.
mg/dscm
Inlet
kg/hr (10'3)
ing/ Ah
Outlet
mg/dscm kg/hr (10~3)
mg/Ah
Efficiency,
percent4
Without balls
1
2
3
AVG
With balls
4
5
AVG
3.94
4.02
5.28
4.41
1.17
0.74
0.96
20.6
22.6
29.1
24.1
6.6
4.1
5.4
6.87
7.53
5.39
6.60
2.20
1.37
1.79
0.044
0.035
0.051
0.043
0.032
0.028
0.030
0.26
0.22
0.32
0.27
0.20
0.18
0.19
0.087
0.073
0.059
0.073
0.067
0.060
0.064
98.7
99.0
98.9
98.9
97 J)
95.6
96.5
Efficiencies are calculated from mass emission rates, and the average is based on averaging efficiencies for
each run.
When polypropylene balls were used (test run Nos. 4 and 5),
inlet emissions averaged 0.96 mg/dscm (0.42 x 10~3 gr/dscf), or
5.4 x 10~3 kg/hr (12 x 10~3 Ib/hr). Emissions measured at the
outlet under these conditions averaged 0.03 mg/dscm
(0.01 x 10'3 gr/dscf), or 0.19 x 10'3 kg/hr (0.42 x 10"3 Ib/hr).
The average total current applied during outlet testing was
7,800 Ah, resulting in a process emission rate from the mist
eliminator of 0.06 mg/Ah (0.001 gr/Ah). The difference between
the average outlet concentration when polypropylene balls were
used and the average outlet concentration when no balls were used
is insignificant. Even when the inlet concentration was
artificially lowered (i.e., with the use of polypropylene balls
on the plating tank), the performance of the mesh-pad mist
eliminator remained essentially the same. [For a further
discussion of the efficiency of polypropylene balls, see
Section 4.3.1.7.]
4.3.1.4 Discussion of Mesh-Pad Mist Eliminator Performance
Data. Table 4-12 presents the performance data for Plants E, F,
4-48
-------
and G. The four-stage mist eliminator at Plant E contained two
sets of overlapping-type blades and two mesh pads installed in
series. Units at Plants F and G each contained two mesh pads in
series. A graphic illustration of the outlet concentrations for
each plant is presented in Figure 4-14. Each of the units
achieved consistent average outlet concentrations. The higher
inlet concentrations at Plant F resulted in a lower average
outlet process emission rate and a higher average percent
efficiency, compared to the results for Plants E and G. However,
because of the variation in inlet loadings among the three
plants, a meaningful comparison of performance levels based on
outlet process emission rate or percent efficiency cannot be
made.
TABLE 4-12. PERFORMANCE DATA FOR MESH-PAD MIST
ELIMINATORS--PLANTS E, F, AND G (AVERAGES)
Plant
E
F
G
Concentration, mg/dscm Outlet proce
emission rat
Inlet Outlet mg/Ah
ss
e, Efficiency,
percent
3.07 0.040 0.078 98.7
11.40 0.033 0.042 99.7
4.41 0.043 0.073 98.9
o.o7
006
0.05
0.04
001
0.02
0.01
n
OUTLET CONCENTRATION. UG/DSCU
„
L 3 P
h i
a
L1
*
_ tj
c r G
PUNT NAME
Figure 4-14. Outlet concentration data for mesh-pad mist
eliminators.
4-49
-------
Based on a comparison of outlet concentrations, the
chevron-blade component of the mist eliminator system at Plant E
does not directly contribute to the performance level of the
control device. The sole purpose of the chevron-blade section is
to reduce the inlet loading on the mesh pads and thus minimize
plugging of the pads. This, in effect, helps to prevent •"
degradation in the efficiency of the mist eliminator system.
4.3.1.5 Wet Scrubber Tests.
4.3.1.5.1 Plant I. Plant I is a job shop that performs
hard chromium electroplating of industrial machine parts,
industrial rolls, and steel tubing. The facility consists of
three plating tanks. During the source test program, only two
tanks, designated as the 23-ft and 10-ft tanks, were operated."
One tank is 7.0 m (23.0 ft) long, 0.9 m (3.0 ft) wide, and
1.2 m (4.0 ft) deep and holds about 6,850 L (1,810 gal) of
plating solution. The tank is equipped with one 6,000-A and
three 1,000-A rectifiers. When industrial rolls or tubing are
plated, the 6,000-A rectifier is used; when smaller and different
kinds of parts are plated, up to four work stations can be set up
in the tank. Three of the work stations are charged with the
1,000-A rectifiers, and one work station is charged with the
6,000-A rectifier.52
The other tank is 3.0 m (10.0 ft) long, 0.9 m (3.0 ft) wide,
and 1.2 m (4.0 ft) deep and holds about 2,990 L (790 gal) of
plating solution. The 10-foot tank contains up to five work
stations, each of which is charged with a separate 1,000-A
rectifier. During this source test program, the 23-foot and
10-foot tanks were divided into two and five work stations,
respectively.52
The plating solution used in the tanks is a conventional
hard chromium plating solution containing about 240 g/L
(32 oz/gal) of chromic acid and about 2.40 g/L (0.32 oz/gal) of
sulfuric acid catalyst.52 The baths are typically operated at
60°C (140°F).
All three tanks are equipped with double-sided draft hoods
that are installed along the length of each tank. All three
4-50
-------
tanks are ducted together and vented to a scrubber located
outside the plant building. The scrubber, installed in 1984, is
a horizontal-flow, single packed-bed unit equipped with a self-
contained recirculation system. The scrubber water drains into a
sump in the bottom of the scrubber and is recirculated by a
0.75-horsepower pump. A sensor is used to monitor the water
level in the sump. About four times a day, clean water is
automatically added over the packed bed when the sensor indicates
that water is needed to replace evaporation losses. The scrubber
water is drained to the plating tanks approximately once a day to
make up for plating solution evaporation losses. The scrubber is
then recharged with clean water. Water is sprayed through six
nozzles countercurrent to the flow of the gas stream. The packed
bed is 142 cm (56 in.) in height and width and 30 cm (12 in.) in
depth and contains polypropylene, spherical-type mass packing
that is continuously washed with water. A two-stage mist
elimination section is located behind the packed bed.53
The gas flow rate to the scrubber during testing averaged
290 m3/min (10,300 ft3/min), and the water flow rate was about
130 L/min (35 gal/min). The L/G ratio was 450 L/min/1,000 m3/min
(3.4 gal/min/1,000 ft3/min), and the pressure drop across the
scrubber was 0.5 kPa (2 in. w.c.).54
Hard chromium plating facilities that use scrubbers
typically recirculate the scrubber water continuously to reduce
both water consumption and wastewater treatment costs and to
recover chromic acid for use as plating solution makeup. The
purpose of this emissions test was to determine the performance
capability of the single packed-bed scrubber and assess the
effect on scrubber performance of increasing chromic acid
concentrations in the scrubber water. Three emissions test runs,
each 2 hours in duration, were conducted simultaneously at the
inlet and outlet of the scrubber for each of four target level
scrubber water concentrations. The target level scrubber water
chromic acid concentrations were selected to represent the range
of concentrations that were believed to occur under typical
operating conditions. These levels were 0, 30, 60, and 120 g/L
4-51
-------
(0, 4, 8, and 16 oz/gal). The chromic acid concentration in the
scrubber water was artificially increased after each test series
by spiking the scrubber water with plating solution taken from
the 23-ft tank. Grab samples of the scrubber water were taken
from the scrubber recirculation sump at the beginning, middle,
and end of each test run. The composite samples were analyzed
onsite using a spectrophotometer to determine the chromic acid
concentration. The actual concentrations observed during testing
averaged 1.6, 25.1, 45.9, and 99.9 g/L (0.22, 3.36, 6.13, and
13.3 oz/gal),54
During the emissions test, the third tank was not operating,
so the ventilation hood on the tank was dampered off to increase
the ventilation rate for the 23-ft and 10-ft tanks that were in
operation during the test.
The emission test results for hexavalent chromium are
presented in Table 4-13. Hexavalent chromium emissions measured
at the inlet averaged 5.51 mg/dscm (2.4 x 10~3 gr/dscf), or
0.090 kg/hr (0.20 Ib/hr). Hexavalent chromium emissions measured
at the outlet averaged 0.030 mg/dscm (1.3 x 10"5 gr/dscf), or
0.521 x 10~3 kg/hr (1.2 x 10~3 Ib/hr). The efficiency of the
scrubber ranged from 99.1 to 99.6 percent. Based on an average
process emission rate of 7,500 Ah during outlet testing, the
hexavalent chromium process emission rate from the scrubber was
0.143 mg/Ah (0.002 gr/Ah).
4-52
-------
TABLE 4-13. PERFORMANCE DATA FOR PLANT I
55
Sample
No.
1
2
3b
AVG
4C
5
6
AVG
7
8
9
AVG
10
11
12
AVG
SERIES
AVG
mg/dscm
4.50
7.07
7.04
6.20
15.90
5.48
6.42
5.95
4.90
4.59
4.38
4.62
6.07
5.50
4.62
5.40
5.51
Inlet
kg/hr (10'3)
74.3
117
117
103
255
87.4
103
95.2
79.7
75.6
71.7
75.7
100
89.4
74.4
87.9
90.0
rag/Ah
12.2
17.7
18.0
16.0
59.9
18.6
24.4
21.5
24.6
23.5
26.2
24.8
31.5
28.7
22.3
27.5
22.5
mg/dscm
0.022
0.028
0.146
0.025
0.023
0.028
0.025
0.025
0.030
0.039
0.034
0.034
0.032
0.032
0.040
0.035
0.030
Outlet
kg/hr (lO'3)
0.381
0.491
2.56
0.436
0.400
0.484
0.431
0.438
0.517
0.680
0.578
0.592
0.549
0.548
0.676
0.591
0.521
mg/Ah
0.062
0.074
0.391
0.068
0.093
0.101
0.102
0.099
0.159
0.214
0.211
0.195
0.174
0.175
0.202
0.184
0.143
Efficiency,
percent*
99.5
- 99.6
•~ _
99.6
--
99.4
99.6
99.5
99.4
99.1
99_.2
99.2
99.5
99.4
99.1
99.3
99.4
Efficiencies are calculated from mass emission rates, and the average is based on averaging efficiencies for
each run.
"Results for the outlet test of this run were not included hi the average; heavy rain entered the stack during
testing and may have biased the results.
cResults for the inlet test of this run were not included in the average; the nozzle may have contacted the duct
wall during testing.
The effect of increasing chromic acid concentrations in the
scrubber water is shown in Figure 4-15. Figure 4-15 is a graph
of the range of hexavalent chromium concentrations in the outlet
gas stream measured at each of the chromic acid concentrations in
the scrubber water. As shown in this figure, it appears that
scrubber water chromic acid concentrations above 25.1 g/L
(3.36 oz/gal) have a negative effect on the performance level of
the scrubber. The average outlet hexavalent chromium concentra-
tion increased from 0.025 mg/dscm (1.1 x 10"5 gr/dscf) to
0.035 mg/dscm (1.5 x 10"5 gr/dscf) between the first two test
series and the last two test series. The effect of the higher
scrubber concentrations on the performance of the scrubber is
also supported by the fact that there was no overlap in the data
4-53
-------
OUTLET CONCENTRATION. UG/DSCU
0.04
0.02
0.01
1.6
2S.1 45.9
CHROMIC ACID CONCENTRATION. C/L
99.9
Figure 4-15. Performance data for the packed-bed
scrubber at Plant I.
ranges between the first two test series and the last two test
series. In addition, the amount of workload processed during the
first two test series when the scrubber water concentration was
below 30 g/L (4 oz/gal) averaged 10,360 Ah, and during the
remaining two test series when the scrubber water concentration
was above 46 g/L (6 oz/gal) the workload averaged 6,260 Ah. If
the performance of the scrubber was not affected by the scrubber
water concentration, it would be anticipated that the outlet
hexavalent chromium concentration would be the same or slightly
less than that measured during the first two test series.
Therefore, the results of these tests suggest that chromic acid
concentrations in the scrubber water should be below 46 g/L
(6 oz/gal) to optimize the performance level of the scrubber.
4.3.1.5.2 Plant K. Plant K is a manufacturer of parts for
textile machinery. Reeds and combs for textile looms and other
miscellaneous parts undergo hard chromium plating in four plating
tanks.
56
During this EPA source test, only three of the four tanks
were in operation (Tanks 1, 2, and 4). The dimensions and
operating parameters for these tanks are presented in Table 4-14.
The plating solution used in the tanks is a conventional hard
4-54
-------
chromium plating solution containing about 250 g/L (33 oz/gal) of
chromic acid and about 2.5 g/L (0.33 oz/gal} of sulfuric acid.
Average plating bath temperatures were 52°C (125°F) for Tanks 1
and 2 and 43°C (110°F) for Tank 4. Current applied to all of the
tanks during testing ranged from 400 to 2,230 A. °
TABLE 4-14. DIMENSIONS AND OPERATING PARAMETERS OF HARD CHROMIUM
PLATING TANKS 1, 2, AND 4 TESTED AT PLANT K
Tank
No. Dimensions (l,w,d) , m (ft)
1
2
4
3
3
2
.8,0
.0,0
.1,0
.9
.5
.8
,0.9
,0.9
,0.9
(12.5,3.0,3.0)
(10.0,1.8,3.0)
(6.8,2.5,3.0)
Capacity, L Voltage,
(gal) voltsa
2,
1,
1,
650
290
210
(700)
(340)
(320)
15
15
30
Current,
amperes^-
10,
6,
5,
000
000
000
aValues represent maximum operating values.
Tanks 1 and 4 are equipped with push-pull emission capture
systems, and Tank 2 is equipped with a single-sided draft hood.
Emissions from all three tanks are ducted to a fume scrubber
system that is located on the roof of the plating shop. The
scrubber is a horizontal-flow, double packed-bed unit that was
installed in 1981. The packed beds are 30.5 cm (12 in.) deep and
are filled with polypropylene spherical-type mass packing. The
design gas flow rate of the scrubber is 540 standard m3/min
(19,000 standard ft3/min). During testing, the actual gas flow
rate averaged 510 m3/min (18,100 ft3/min). Scrubber water flow
during the tests was set at 450 L/min (120 gal/min). This flow
resulted in a L/G ratio of 860 L/min/1,000 m3/min
(6.4 gal/min/1,000 ft3/min). The pressure drop during testing
ranged from 0.7 to 0.8 kPa (2.9 to 3.2 in. w.c.). Each packed
bed is 30.5 cm (12 in.) deep.
Six spray nozzles are located in front of each packed bed
and are used to spray the beds continuously countercurrent to the
flow of the gas stream. Chromic acid mist that impinges on the
packing material is washed to the bottom of the scrubber. The
scrubber water flows by gravity from the scrubber to a 910-L
4-55
-------
(240-gal) recirculation tank located inside the plating shop.
Clean water is used to make up for evaporation losses from the
system. The ductwork is washed down once a month with water that
subsequently drains into the plating tanks. The scrubber also
contains a chevron-blade mist elimination section located
downstream of the second packed bed.57
Three emissions tests were conducted at the inlet and outlet
of the scrubber. The test results are summarized in Table 4-15.
Emissions measured at the inlet averaged 1.7 mg/dscm
(0.7 x 10"3 gr/dscf), or 46 x 10"3 kg/hr (100 x 10"3 Ib/hr).
Emissions measured at the outlet averaged 0.052 mg/dscm
(0.02 x 10'3 gr/dscf}, or 1.5 x 10"3 kg/hr (3.4 x 10'3 Ib/hr).
The removal efficiency of the scrubber ranged from 94.9 to
98.1 percent. The average total current applied to the process
during outlet testing was 8,750 Ah. Therefore, the hexavalent
chromium process emission rate from the scrubber was 0.56 mg/Ah
(0.009 gr/Ah).
TABLE 4-15. PERFORMANCE DATA FOR PLANT K
58
Run No.
1
2
3
AVG
mg/dscm
2.68
1.20
1.13
1.67
Inlet
kg/hr (ID'3)
74.4
33.6
31.3
46.4
mg/Ah
19.6
16.1
10.8
15.5
mg/dscm
0.051
0.052
0.055
0.052
Outlet
kg/hr (ID'3)
1.45
1.51
1.61
1.52
mg/Ah
0.382
0.726
0.561
0.556
Efficiency,
percent*
98.1
95.5
94.9
96.2
Efficiencies are calculated from mass emission rates, and the average is based on averaging efficiencies for
each run.
4.3.1.5.3 Plant L. Plant L is a job shop that specializes
in hard chromium electroplating of crankshafts. Tests were
conducted on a single packed-bed scrubber that controls emissions
from a plating tank 9.1m (30 ft) long, 1.1 m (3.5 ft) wide, and
1.2 m (4.0 ft) deep. The tank holds approximately 10,410 L
(2,750 gal) of plating solution. The plating tank is equipped
with a single rectifier rated at 15 V and 8,000 A. The tank
4-56
-------
contains a conventional hard chromium plating solution consisting
of 240 g/L (32 oz/gal) of chromic acid and 2.4 g/L (0.32 oz/gal)
of sulfuric acid. The plating solution is maintained at 54°C
(130°F),59
The capture and control system on the plating tank consists
of a double-sided draft hood that is vented to a horizontal-flow
single packed-bed scrubber that was installed in 1988. The
design gas flow rate to the scrubber is 450 m3/min
(16,000 ft^/min).^° The scrubbing water flow rate is
approximately 180 L/min (48 gal/min). During testing, the actual
inlet gas flow rate to the scrubber averaged 575 rrr/min
(20,300 ft^/min), and the monitored pressure drop was close to
the design pressure drop of 0.5 kPa (2.0 in. w.c.).
Within the scrubber system, the velocity of the gas stream
is reduced to approximately 134 m/min (440 ft/min), and the gas
stream is humidified by a spray of water. Water is sprayed
countercurrent to the flow of the gas stream through 10 spray
nozzles. The saturated gas stream then passes through a packed
bed of polypropylene, spherical-type mass packing. The packed
bed is wetted continuously with scrubbing water supplied by the
series of spray nozzles in front of the bed. The packed bed is
approximately 2.0 m (6.4 ft) high, 1.9 m (6.2 ft) wide, and
0.30 m (1.0 ft) deep. Entrained mist and water droplets impinge
on the packing and drain into the sump. Behind the packed bed is
a two-stage mist elimination section that removes entrained water
droplets. The first stage allows large droplets to settle by
gravity to the bottom of the scrubber. The second stage contains
a series of vertically mounted chevron blades that change the
direction of the gas flow four times at 30° angles, forcing
chromic acid droplets to impinge on the blades. The mist
eliminator is not washed down.^
The scrubber water drains into a sump in the bottom of the
scrubber and is recirculated by a pump. A level indicator (sight
gauge) is used to monitor the water level in the sump, which
holds approximately 450 L (120 gal) of water. Once a week, the
water in the sump is drained into a 5,680-L (1,500-gal) holding
4-57
-------
tank and the sump is recharged with fresh water. Although the
plating tank is operated 24 hours a day, the recirculation system
on the scrubber is turned off from 11:30 p.m. to 7:30 a.m., when
there are no plant employees onsite.60
Test results obtained on another horizontal-flow, single
packed-bed scrubber (Plant I) demonstrated that better than
99 percent control efficiency and an average outlet hexavalent
chromium concentration of 0.030 mg/dscm (1.3 x 10"5 gr/dscf) was
achievable. The double packed-bed scrubber tested at Plant K
achieved a lower control efficiency of 96 percent, with an
average hexavalent chromium concentration of 0.052 mg/dscm
(2.3 x 10"5 gr/dscf). The scrubber tested at Plant I was
somewhat unique in that it was equipped with an overhead spray
system that periodically flooded and cleaned the scrubber packing
media with fresh water. Based on the test results obtained from
Plants I and K, it appeared that periodic flooding of the packing
media may prevent deterioration in scrubber performance caused by
chromium buildup. Therefore, the purpose of the source test at
Plant L was to determine if the periodic flooding action provided
by the scrubber overhead weir system significantly improved the
scrubber performance and to establish the average performance
level of the scrubber system.
Prior to emissions testing, the scrubber was retrofitted
with an overhead weir so that the scrubber could be operated with
and without periodic fresh water washdown of the scrubber
packing. Three mass emissions test runs were conducted at the
inlet and outlet of the scrubber at each of the following
conditions: (1) the scrubber recirculation system was in
operation and any required makeup water was supplied by a hose
through one of the scrubber's inspection doors, and (2) the
scrubber recirculation system was in operation and all required
makeup water was supplied through a pipe that extended out about
1.0 to 13 cm (4 to 5 in.) over the top of the packed bed. Two
subsequent test runs were conducted at the inlet and outlet of
the scrubber with the scrubber recirculation system in operation
4-58
-------
and a continuous flow of fresh water supplied through the
overhead weir at a rate of 7.6 L/min (2.0 gal/min).
Prior to test run Nos. 1 and 3, the sump in the bottom of
the scrubber was drained to the holding tank and the sump was
recharged with fresh water supplied by a hose through one of the
scrubber's inspection doors. During test run Nos. 1 through 3,
makeup water required by the scrubber to replace evaporation
losses was added through the inspection doors with a water hose.
Prior to test run No. 4, the scrubber was thoroughly cleaned by
draining the sump and washing down the inside walls, packing
media, and mist elimination section with a pressurized water
hose. During test run Nos. 4 through 6, makeup water required by
the scrubber to replace evaporation losses was supplied through
the pipe located over the top of the packed bed. Prior to test
run No. 7, the scrubber was recleaned. During test run Nos. 7
and 8, makeup water was added continuously over the top of the
packed bed through the overhead weir at a flow rate of 7.6 L/min
(2.0 gal/min). 61
The emissions test results for hexavalent chromium are
presented in Table 4-16. A plot of the range of outlet
hexavalent chromium concentrations at each washdown condition is
presented in Figure 4-16. The first three emissions test runs
were conducted without overhead washdown of the scrubber packing.
For these runs, emissions measured at the inlet averaged
0.72 mg/dscm (0.31 x 10"3 gr/dscf), or 23 x 10"3 kg/hr
(51 x 10 Ib/hr). Emissions measured at the outlet averaged
0.04 mg/dscm (0.02 x 10~3 gr/dscf), or 1.2 x 10"3 kg/hr
(2.6 x 10"3 Ib/hr). Emissions test run Nos. 4, 5, and 6 were
conducted with periodic overhead washdown. The emissions
measured at the inlet for these runs averaged 0.67 mg/dscm
(0.29 x 10"3 gr/dscf), or 22 x 10"3 kg/hr (47 x 10"3 Ib/hr).
Outlet emissions averaged 0.02 mg/dscm (0.01 x 10"3 gr/dscf), or
0.71 x 10"3 kg/hr (1.6 x 10"3 Ib/hr). Test run Nos. 7 and 8 were
conducted with continuous overhead washdown of the scrubber
packing. Emissions at the inlet averaged 0.72 mg/dscm
(0.32 x 10'3 gr/dscf), or 24 x 10~3 kg/hr (52 x 10"3 Ib/hr).
4-59
-------
Emissions measured at the outlet averaged 0.02 mg/dscm
(0.01 x 10"3 gr/dscf), or 0.65 x 10"3 kg/hr (1.4 x 10"3 Ib/hr).
TABLE 4-16. PERFORMANCE DATA FOR PLANT L62
Run No. ~
Inlet
mg/dscm
kg/hr (10-3
) mg/Ah
Outlet
mg/dscm kg/hr (10~3)
mg/Ah
Efficiency,
percent*
No overhead washdown
lb
2
3
AVG
0
0
0
0
.299
.646
.783
.715
9
7
20.8
25.
23.
2
0
3.53
6.93
11.0
8.97
0.038
0.039
0.041
0.039
1
1
1
1
.13
.19
.24
.19
0.
0.
0.
419
397
539
0.452
—
94.3
95.1
94.7
Periodic overhead washdown
4
5
6
AVG
0
0
0
0
.850
.576
.579
.668
27.
18.
18.
21.
8
7
6
7
7.72
5.19
5.03
5.98
0.026
0.022
0.023
0.023
0
0
0
786
646
684
0.705
0.
0
0
221
179
185
0.195
97.2-
96.5
96.3
96.6
Continuous overhead washdown
7
8
AVG
0
0
.752
.693
0.723
24.
22.
23.
7
5
6
7.89
8.04
7.97
0.023
0.020
0.021
0
0
0
686
613
650
0.219
0.219
0.219
97.2
97.3
97.3
Efficiencies are calculated from mass emission rates, and the average is based on an averaging efficiencies for
each run.
^Results for the inlet test of this run were not included in the average due to possible sample contamination.
As shown in Figure 4-16, periodic washdown improved the
performance level of the scrubber, whereas continuous washdown
did not provide any additional benefit beyond that achieved by
periodic washdown. At comparable inlet loadings, the average
scrubber removal efficiencies were 94.7 percent when no overhead
washdown was used, 96.6 percent with periodic washdown, and
97.3 percent with continuous washdown. The average hexavalent
chromium process emission rates from the scrubber were 0.45 mg/Ah
(0.007 gr/Ah) with no overhead washdown, 0.20 mg/Ah (0.003 gr/Ah)
with periodic washdown, and 0.22 mg/Ah (0.003 gr/Ah) with
continuous washdown. Therefore, these test results suggest that
periodic flooding of the packing material is beneficial in
maintaining the scrubber performance, but continuous flooding is
unnecessary.
4-60
-------
0 OS
004
003
002 I
OUTLET CONCENTRATION, UC/OSCU
NO
WASHDOWN
PERIODIC
WASHDCWN
WASHDOWN CONDITION
CONTINUOUS
WASHDOWN
Figure 4-16.
Performance data for the packed-bed scrubber
at Plant L.
4.3.1.6 Discussion of Wet Scrubber Tests. Table 4-17 and
Figure 4-17 present the performance data for each of the wet
scrubber systems tested. When the test program began, it was
anticipated that the double packed-bed scrubber would be the most
efficient of the control devices tested because: (1) it operates
at a higher pressure drop than the other devices, and (2) the
redundancy of the second packed bed should provide more impaction
opportunities for the chromic acid mist. However, test results
from Plants I and K clearly demonstrate that the best performance
level was achieved by the single packed-bed scrubber at Plant I.
The average outlet concentration at Plant I was 0.030 mg/dscm
(1.3 x 10"^ gr/dscf), whereas the average outlet concentration
achieved by the double packed-bed scrubber at Plant K was
0.052 mg/dscm (2.3 x 10*5 gr/dscf).
The process operating conditions were evaluated to determine
if there were any operational reasons for the observed results.
The processes tested were representative of typical hard chromium
plating operations. Also, the scrubbers appeared to be operated
normally during testing. All had pressure drops, L/G ratios, and
gas velocities at or near acceptable design levels. The size of
the packing used in the scrubbers was also comparable.
4-61
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TABLE 4-17. PERFORMANCE DATA FOR PACKED-BED SCRUBBERS
PLANTS I, K, AND L (AVERAGES)
Concentration, mg/dscm Outlet process
Plant
Ia
!*>
Ic
!<*
SERIES
K
Le
Lf
L9
Inlet
6.20
5.95
4.62
5.40
5.51
1.67
0.715
0.668
0.723
emission rate,
Outlet mg/Ah
0.025
0.025
0.034
0.035
0.030
0.052
0.039
0.023
0.021
0.068
0.099
0.195
0.184
0.143
0.556
0.452
0.195
0.219
Efficiency,
percent
~~99.6
99.5
99.2
99.3
99.4
96.2
94.7
96. -6
97.3
aTest runs with an average scrubber water chromic acid concentration of 1.6 g/L.
^"est runs with an average scrubber water chromic acid concentration of 25.1 g/L.
cTest runs with an average scrubber water chromic acid concentration of 45.9 g/L.
Test runs with an average scrubber water chromic acid concentration of 99.9 g/L.
^est runs with no overhead washdown.
Test runs with periodic overhead washdown.
§Test runs with continuous overhead washdown.
0 06
0 04
0031-
0.02
0.01
OUTLET CONCENTRATION. UC/DSCH
1-1 t-2
PLANT NAME
Figure 4-17. Outlet concentration data for packed-bed scrubbers
4-62
-------
At the time of the emissions tests, the single packed-bed
scrubber at Plant I was 2 years old, and the double packed-bed
scrubber at Plant K was 4 years old. Any scrubber system that
has been in operation for any length of time requires a certain
amount of routine maintenance for the scrubber to operate at
optimum performance levels. Each of the scrubbers tested^was
inspected and any needed repairs were made prior to the source
tests.
The single packed-bed scrubber at Plant I was equipped with
an overhead water distribution weir. This feature was not
included in the double packed-bed scrubber at Plant K. The
overhead weir in the single packed-bed scrubber was located above
the packed-bed and was activated when makeup water was required
to refill the sump due to evaporation losses or following
drainage of the sump to the plating tank. The double packed-bed
scrubber at Plant K was equipped with a water line that added
makeup water directly to the sump rather than over the packed
bed. The flooding action provided by the addition of water
through an overhead weir provides frequent cleaning of the
packing media and may prevent degradation in the performance of
the packed-bed scrubber. Therefore, it was thought that the
performance difference between the two scrubbers might be
accounted for by the presence of the overhead weir in the single
packed-bed scrubber tested.
At Plant L, the primary purpose of the source test was to
determine if the periodic flooding action provided by the
scrubber overhead weir system significantly improved the scrubber
performance. Three sets of test runs were conducted: one set
with no overhead washdown, one set with periodic overhead
washdown, and one set with continuous overhead washdown. As
shown in Table 4-17 and Figure 4-17, the results of this test
indicated there was an improvement in the performance level of
the scrubber when periodic washdown was used. With no overhead
washdown of the scrubber packing, the average removal efficiency
was 94.7 percent and the outlet hexavalent chromium concentration
averaged 0.039 mg/dscm (1.7 x 10"5 gr/dscf). With periodic
4-63
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washdown, the efficiency increased to 96.6 percent and the
average outlet hexavalent chromium concentration was reduced to
0.023 mg/dscm (1.0 x 10"5 gr/dscf). The use of continuous
overhead washdown did not significantly increase the control
efficiency or reduce the outlet concentration of the scrubber
over that achieved with periodic washdown. These data suggest
that periodic overhead washdown of the scrubber packing is needed
to maintain the scrubber at optimum performance levels.
Results of the recirculation study at Plant I showed that
increasing the scrubber water chromic acid concentration from the
baseline of 1.6 g/L (0.22 oz/gal) to 99.9 g/L (13.3 oz/gal) did
not decrease the control efficiency of the scrubber below
99 percent. However, the outlet hexavalent chromium
concentration increased between the two test series conducted at
scrubber water concentrations of 25.1 g/L (3.4 oz/gal) and
45.9 g/L (6.1 oz/gal). At the baseline concentration of 1.6 g/L
(0.22 oz/gal), hexavalent chromium emissions from the scrubber
were 0.44 x 10"3 kg/hr (0.96 x 10~3 Ib/hr). Increasing the
concentration to 25.1 g/L (3.4 oz/gal) resulted in no significant
measured increase in outlet hexavalent chromium emissions over
the baseline condition. However, for scrubber water
concentrations of 45.9 and 99.9 g/L (6.1 and 13.3 oz/gal),
hexavalent chromium emissions increased by about 34 percent
(0.15 x 10~3 kg/hr [0.34 x 10~3 Ib/hr]) above baseline. This is
an indication that the scrubber water chromic acid concentration
needs to be below 46 g/L (6 oz/gal) for optimum scrubber
performance.
4.3.1.7 Discussion of Performance Data for Polypropylene
Balls. During the testing of the mesh-pad mist eliminator at
Plant G (see Section 4.3.1.3.3), the plating tank was operated
with and without polypropylene balls on the surface of the
plating solution. The cover was two to three layers thick in
most places. In typical industrial applications, coverage is
usually not as complete as that tested.
Two test runs were conducted while the balls were in place,
and the results are presented in Table 4-18. Emissions measured
4-64
-------
at the inlet of the mist eliminator when the balls were in place
(test run Nos. 4 and 5) averaged 0.96 mg/dscm
(0.42 x 10"3 gr/dscf), or 5.4 x 10~3 kg/hr (12 x 10"3 Ib/hr).
These values were compared to measurements made at the inlet when
no balls were used (test run Nos. 1 and 2) to assess the
performance of polypropylene balls in controlling chromium
emissions. Run Nos. 1 and 2 were used for comparison because the
same pieces were being plated at the same current and plating
times as those in test run Nos. 4 and 5. The removal efficiency
averaged 74.9 percent.
TABLE 4-18. PERFORMANCE DATA FOR PLANT G--POLYPROPYLENE BALLS51
Without balls
Run No.
l(4)b
2(5)b
AVG
mg/dscm
3.94
4.02
3.98
kg/hr (ID'3)
20.6
22.6
21.6
mg/Ah
mg/dscm
6.87 1.17
7.53 0.74
7.20 0.96
With balls
kg/hr (lO'3)
6.6
4.1
5.4
mg/Ah
2.20
1.37
1.79
Efficiency,
percent^
68.0
81.9
74.9
Efficiencies are calculated from mass emission rates, and the average is based on averaging efficiencies for
each run.
"Run Nos. 1 and 2 were conducted with no polypropylene balls. Run Nos. 4 and 5 were conducted with
polypropylene balls.
4.3.2 Tests at Decorative Chromium Electroplating Operations
4.3.2.1 Chemical Fume Suppressant Testing--Plant N.
Plant N is a small job shop that performs decorative chromium
electroplating of automotive trim. The plating facility consists
of two decorative chromium plating lines: the main plating line
and a rework plating line.63 Tests were conducted at the
chromium plating tank in the main plating line to characterize
the performance of two types of chemical fume suppressants. The
chromium plating segment of this line consists of a chromium
predip, the plating tank, a chromium saver tank, and three
bisulfite rinses. The plating line is serviced by an
automatically controlled overhead conveyor that transfers racks
of parts to each tank in a programmed sequence.
4-65
-------
The chromium plating tank is 3.4 m (11.0 ft) long, 0.85 m
(2.8 ft) wide, and 1.5 m (5.0 ft) deep and is divided into six
cells that are each 0.55 m (1.8 ft) long. The plating tank holds
approximately 3,940 L (1,040 gal) of plating solution, which
contains chromic acid in a concentration of 280 g/L (37 oz/gal)
of water. The plating solution contains both fluoride and
sulfuric acid catalysts. The temperature of the plating bath is
maintained between 43° and 47°C (110° and 116°F). The plating
tank is equipped with three rectifiers.
After immersion into the plating tank, the surface area of
the parts is activated for 15 seconds prior to plating. During
activation, the rectifier connected to cell No. 1 is operated at
0 to 5.0 V and 0 to 200 A. After activation, the racks are
automatically moved toward the center of the plating tank.
During plating, the rectifier connected to cell Nos. 2 through 5
is set at 5.2 V and 3,000 A. The rectifier connected to cell
No. 6 is set at 3.0 V and minimal to no current.^4
The chromium plating tank is equipped with a single-sided
draft hood. The exhaust gases captured by the hood are ducted to
a vertical-flow, single packed-bed scrubber.
During the source test, the chromium plating tank was
operated under three conditions: (1) without a fume suppressant,
(2) with a foam blanket, and (3) with a "combination" fume
suppressant consisting of a foam blanket and a wetting agent.
The foam blanket forms a layer of foam approximately 2.5 cm
(1.0 in.) thick over the plating bath when the plating solution
is agitated by the gas bubbles formed during the plating process.
The combination fume suppressant forms a layer of foam 2.5 cm
(1.0 in.) thick over the surface of the plating solution and
lowers the surface tension of the plating solution from
70 dynes/cm (4.8 x 10~3 Ib^/ft) to below 40 dynes/cm
(2.7 x 10"3 lbf/ft). Because the surface tension of the plating
solution is lower, the gases formed escape the surface with less
of a "bursting" effect, and less mist is produced. The foam
layer is designed to capture any mist that is formed. The foam
blanket and the combination fume suppressants used during the
4-66
-------
test program were applied and maintained according to the
manufacturer's recommendations.
Three test runs at each condition were conducted at a
location in the ductwork between the ventilation hood and the
inlet of the scrubber to characterize the performance of the two
types of chemical fume suppressants. The results of testing with
and without fume suppressants are presented in Table 4-19.
Hexavalent chromium emissions measured during the uncontrolled
runs (when no fume suppressant was used) averaged
9.2 x 10"1 mg/dscm (0.40 x 10~3 gr/dscf), or 3.6 x 10"3 kg/hr
(7.9 x 10~3 Ib/hr).
Hexavalent chromium emissions measured during the test runs
when the foam blanket was used averaged 4.7 x 10"3 mg/dscm
(2.0 x 10'6 gr/dscf), or 1.8 x 10"5 kg/hr (4.0 x 10'5 Ib/hr).
Hexavalent chromium emissions measured during the test runs when
the combination fume suppressant was used averaged
2.2 x 10"3 mg/dscm (9.5 x 10"7 gr/dscf), or 8.3 x 10"6 kg/hr
(1.8 x 10~5 Ib/hr).
The efficiency of the foam blanket ranged from 99.3 to
99.6 percent for the removal of hexavalent chromium emissions.
The efficiency of the combination fume suppressant ranged from
99.7 to 99.9 percent for the removal of hexavalent chromium
emissions. Based on average total current of 8,500 Ah and
10,500 Ah during testing, the hexavalent chromium process
emission rates when the foam blanket and combination fume
suppressant were maintained in the tank were 0.007 mg/Ah
(1.0 x 10"4 gr/Ah) and 0.003 mg/Ah (5.0 x 10"5 gr/Ah),
respectively.
4.3.2.2 Discussion of Chemical Fume Suppressant Tests. The
test results from Plant N show that removal efficiencies of
chemical fume suppressants ranged from 99.3 to 99.9 percent for
hexavalent chromium with an average hexavalent chromium emission
rate of 1.3 x 10"5 kg/hr (2.9 x 10"5 Ib/hr), or 0.005 mg/Ah
(6.9 x 10"5 gr/Ah).
4-67
-------
TABLE 4-19. PERFORMANCE DATA FOR PLANT N- -HEXAVALENT
CHROMIUM EMISSIONS65
Efficiency,
Run No. mg/dscm kg/hr (10~3) mg/Ah percent3-
Uncontrolled
1
2
3
AVG
0.
0.
0.
0.
846
923
993
921
3.
3.
3.
3.
3
6
9
6
1
1
1
1
.22
.50
.39
.37
Foam blanket
4
5
6
AVG
0.
0.
0.
0.
003
007
004
005
Combination
7
8
9
AVG
0.
0.
0.
0.
002
001
003
002
0.
0.
0.
0.
foam blanke
0.
0.
0.
0.
013
027
015
018
t and
007
005
013
008
0
0
0
0
.005
.010
.005
.007
99
99
99
99
.6
.3 -
.6
.5
wettina aqent
0
0
0
0
.003
.002
.005
.003
99
99
99
99
.8
.9
.7
.8
aEfficiencies are calculated from mass emission rates, and the
average is based on averaging efficiencies for each run.
4.3.3 Summary and Discussion of Emission Test Results
The emission data for all of the control techniques tested
are summarized in Tables 4-4a and 4-4b. During the early part of
the test program, total chromium and hexavalent chromium were
measured at each site. The results of these tests indicated that
the hexavalent chromium levels and the total chromium levels were
about the same, so emissions could all be assumed to be
hexavalent chromium. For this reason, and for reasons discussed
in Appendix D (Emission Measurements), total chromium analyses
were discontinued for the remainder of the plants tested. The
values for hexavalent chromium were assumed to be approximately
the same as those obtained for total chromium.
4-68
-------
The following is a summary of the conclusions about each
individual control unit tested during the source test program.
Source test results on chevron-blade mist eliminators indicate
that: (1) overlapping-type blades are more effective than wave-
type blades, and (2) a double set of blades does not
significantly increase the performance level beyond that achieved
by a single set of blades. For mesh-pad mist eliminators, the
test results indicate that the units achieved consistent outlet
results, which suggests that the units had comparable performance
levels.
The source test results for packed-bed scrubbers indicate
that: (l) a second packed bed does not improve the performance
level above that achieved by a single packed bed, (2) periodic,
flooding of the packing media with fresh water helps to clean the
packing media and prevent degradation in the scrubbers
performance, and (3) the chromic acid concentration in the
scrubber water should be less than 30 g/L (4 oz/gal) to optimize
the performance level of the scrubber. The test results also
showed that chemical fume suppressants are very effective in
inhibiting chromic acid mist from decorative chromium plating
tanks.
There are three distinct performance levels achieved by the
control devices. The lowest performance level is associated with
the use of chevron-blade mist eliminators, which achieved an
average outlet hexavalent chromium emission concentration of
0.190 mg/dscm (0.08 x 10"3 gr/dscf) for the three chevron-blade
mist eliminators tested. The intermediate performance level is
associated with the use of mesh-pad mist eliminators and packed-
bed scrubbers, which achieved an average outlet hexavalent
chromium concentration of 0.035 mg/dscm (0.02 x 10~3 gr/dscf).
The highest performance level is associated with the use of
chemical fume suppressants (by decorative chromium plating
operations), which achieved an average outlet hexavalent chromium
concentration of 0.0047 mg/dscm (0.002 x 10"3 gr/dscf).
Figure 4-18 is a graphical presentation of the performance
level achievable by chevron-blade mist eliminators. The
4-69
-------
06
0.4
0.2
0.1
OUTLET CONCENTRATION. MS/DSCM
AID
CBME CBME CBME
CONTROL DEVICE/PLANT CODES
OUTLET MASS EMISSION KATE. IS/MR (10-3)
2t-
A B D
CBME CEME CBME
CONTROL DEVICE/PLANT CODES
1.2
1
o.e
06
0.4
0.2
0
OUTLET PROCESS EMISSION RATE. MS/AH
AID
CBME CBME CBME
CONTROL DEVICE/PLANT CODES
Figure 4-18. Performance data for chevron-blade mist
eliminators.
4-70
-------
individual test averages for the outlet hexavalent chromium
concentration ranged from 0.120 to 0.310 mg/dscm (0.05 x 10~3 to
0.13 x 10"3 gr/dscf). The average mass emission rates varied
from 1.2 x 10"3 to 3.3 x 10'3 kg/hr (2.7 x 10"3 to
7.3 x 10"3 lb/hr), while the average process emission rates
varied from 0.14 to 0.59 mg/Ah (0.002 to 0.009 gr/Ah).
Figure 4-19 is a graphical presentation of the performance
levels achievable by mesh-pad mist eliminators and packed-bed
scrubbers. The individual test averages for the outlet
hexavalent chromium concentration ranged from 0.021 to
0.052 mg/dscm (0.01 x 10"3 to 0.02 x 10~3 gr/dscf). The average
mass emission rates varied from 0.23 x 10"3 to 1.5 x 10"3 kg/hr
(0.51 x 10"3 to 3.4 x 10"3 lb/hr), while the average process
emission rates varied from 0.04 to 0.56 mg/Ah (0.001 to
0.009 gr/Ah). A review of the test data for mesh-pad mist
eliminators and packed-bed scrubbers presented in Tables 4-4a and
4-4b and Figure 4-19 suggests that inlet concentration has an
effect on the performance efficiency of the control devices.
Regardless of the variation in inlet concentrations, outlet
concentrations are fairly constant. A plot of efficiency versus
concentration, presented in Figure 4-20, suggests the
relationship is a logarithmic function. When the log of the
concentrations is plotted versus the corresponding efficiencies
(Figure 4-21), and a linear regression analysis is performed, a
high correlation coefficient is obtained (r = 0.87). To verify
that this correlation does exist, two test series that have a
wide variation in inlet concentrations were selected, and the log
of the concentrations and the corresponding efficiency values
were plotted for each test run. This graph is shown in
Figure 4-22. The linear regression performed on the data
resulted in essentially the same regression line (r = 0.98) as
that shown in Figure 4-21. This supports the conclusion that
inlet concentration has an effect on the performance efficiency
of the control device and that the outlet hexavalent chromium
concentration is a better measure of the performance capability
of the units than percent efficiency.
4-71
-------
OUTLET CONCENTRATION. MC/DSCW
U 1
009
o.oa
007
006
DOS
004
001
0.02
0.01
0
" r
K fj
;
Mr M
5
0 KB0
D R fi
§ B a 0
r Mr Mr ic sc sc sc sc sc sc ic
CONTROL DEV1CE/FLANT CODES
OUTLET MASS RATE. IS/HR (10-3)
1.5
05 r
Q B
B 3
E
Mr
r
Mr
e-i
wr
G-l
Mr
r-i
SC
1-2
SC
I-J
SC
SC
I
sc
t-1
sc
L-J
SC
L-3
SC
CONTROL DEVICE/PLANT CODES
o.a
0.6
0.4
0.2
OUTLET PROCESS EMISSION RATE. MS/AH
I
Mr
F
Mr
s-i e-i
Mr Mr
1-1
K
i-a
sc
i-j
sc
1-4
SC
SC SC 1C SC
CONTROL DEVICE/PLANT CODES
Figure 4-19.
Performance data for mesh-pad mist eliminators and
packed-bed scrubbers.
4-72
-------
o
z
UJ
o
U_
U_
UJ
O
o:
O
o
TOO
99
98
97
96
95
94
2 4 6 8 10
INLET CONCENTRATION, MG/DSCM
12
Figure 4-20. Average control device efficiency versus average
inlet concentration for scrubbers and mesh-pad mist eliminators,
o
z
UJ
o
z
o
o
100
99
98
97
96 H
95 h
94
3.28[log(conc)] + 96.57
r = 0.87
i i i i
-0.2 0 0.2 0.4 0.6 0.8 1
LOG(CONCENTRATION), MG/DSCM
Figure 4-21. Average control device efficiency versus average
(concentration) for scrubbers and mesh-pad mist
eliminators.
4-73
-------
14-1
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D
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6 2
O
CO
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z
O £
Ul
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O
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4-74
-------
In comparing the bar graphs in Figures 4-18 and 4-19,
several observations can be made about the performance levels of
the control devices. The most important observation is that the
outlet concentration levels for packed-bed scrubbers and mesh-pad
mist eliminators are much lower than those for chevron-blade mist
eliminators. However, there is some overlap of the outlet mass
emission rates between the two data graphs. This overlap is a
result of the variance in ventilation rates among the facilities
tested. There is also a significant overlap of the process
emission rate values (mg/Ah) presented in the graphs because
ampere-hour values are a reflection of inlet loadings, which do
not have a significant effect on the outlet concentrations. For
this reason, outlet process emission rate values cannot be "used
to evaluate control device performance.
4-75
-------
4.4 REFERENCES FOR CHAPTER 4
1. American National Standard Practices for Ventilation and
Operation of Open-Surface Tanks. ANSI Z9.1-1977. New York,
American National Standards Institute, Inc. 1977.
pp. 13-14.
2. Industrial Ventilation: A Manual of Recommended Practice.
American Conference of Governmental Industrial Hygienists.
19th edition. 1986. pp. 5-68 to 5-70.
3. Duall Industries, Owosso, Michigan. Technical Bulletin
No. 111-9. Typical Exhaust Hood Applications, Type "ED"
Exhaust Hood. March 3, 1980.
4. Duall Industries, Owosso, Michigan. Technical Bulletin
No. 111-11. Typical Exhaust Hood Applications, Type "B2Ln
Exhaust Hood. October 13, 1975. . _
5. Reference 2, p. 4-21.
6. Memo from Strait, R., MRI, to Vervaert, A., EPA/ISB.
March 6, 1986. Trip report for Duall Industries, Inc.,
Owosso, Michigan. p. 2.
7. Chromium Electroplaters Test Report: Precision Machine and
Hydraulics, Inc., Worthington, West Virginia. Peer
Consultants, Inc., Dayton, Ohio. Prepared for the U. S.
Environmental Protection Agency, Research Triangle Park,
North Carolina. EMB Report 88-CEP-14. September 1988.
p. 6.
8. Fair, J. Liquid-Gas Systems. In: Perry's Chemical
Engineers' Handbook. 6th edition. Perry, R., and D. Green,
eds. New York, McGraw-Hill Book Company. 1984. pp. 18-78.
9. York, 0. Performance of the Wire Mesh Demister. Chemical
Engineering Progress. 5_9_(6) :45-50. June 1963.
10. Schifftner, K. C., and H. E. Hesketh. Wet Scrubbers: A
Practical Handbook. Chelsea, Michigan, Lewis Publishers,,
Inc. 1986. p. 56.
11. Calvert, S., S. Yung, and J. Leung. Entrainment Separators
for Scrubbers: Final Report. U. S. Environmental
Protection Agency, Office of Research and Development,
Washington, D.C. August 1975. p. 65.
12. Telecon. Barker, R., MRI, with Zitko, L., ChromeTech, Inc.
February 21, 1989. Information about mesh-pad mist
eliminators.
4-76
-------
13. Telecon. Kowalski, A., MRI, with Gillette, B., KOCH
Engineering Company, Inc. December 17, 1986. Information
about mist eliminators used to control chromic acid mist.
14. Reference 11, p. 71.
15. Meet Your Pollution Control Requirements With the Leader in
PVC Fabrications. Product Information Brochure. Duall
Industries, Inc., Owosso, Michigan. April 1979. p. 6.
16. KCH Fume Scrubbers: Average Removal Efficiencies. Product
Information Sheet. KCH Services, Inc., Forest City, North
Carolina. 1982.
17. Scrubbers. Product Information Brochure. KCH Services,
Inc., Forest City, North Carolina. 1982. pp. 2-3.
18. Bethea, R. Air Pollution Control Technology. New York_, Van
Nostrand Reinhold Company. 1978. p. 259.
19. Tower Packing and Internals Including Mist Eliminators.
Glitsch, Inc., Dallas, Texas. Bulletin No. 217, 3rd ed.,
1975, pp. 7-8.
20. The Tri-Mer Fan/Separator Product Information Brochure.
Tri-Mer Corp., Owosso, Michigan. Undated, p. 1.
21. Memo from Strait, R., MRI, to Vervaert, A., EPA/ISB.
March 14, 1986. Trip report for Tri-Mer® Corp., Owosso,
Michigan. pp. 2-4.
22. Hesketh, H. E. Air Pollution Control. Ann Arbor, Michigan,
Ann Arbor Science Publishers, Inc. 1981. p. 250.
23. Niehaus Fume Separators. Product Information Brochure.
Niehaus Brothers, Inc., Indianapolis, Indiana. pp. 2-4.
24. Telecon. Barker, R., MRI, with Brown, G., Niehaus Brothers,
Inc. October 1, 1986. Operating parameters for fume
separator scrubbers.
25. Reference 10, p. 9.
26. Fluorine Surfactant FT 248 as a Chrome Bath Wetting Agent
(Chrome Mist Suppressant). Product Information Brochure.
Mobay Chemical Corp., Inorganic Chemicals Division,
Pittsburgh, Pennsylvania, pp. 3, 4.
27. Memo from Strait, R., MRI, to Vervaert, A., EPA/ISB.
March 6, 1986. Trip report for OMI™ International Corp.,
Warren, Michigan. Attachment: Product Information Sheets
for Zero-Mist™, Zero-Mist™ HT, and Zero-Mist™ HT-2.
4-77
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28, Telecon. Cassidy, M., MRI, with Varuolo, A., MacDermid,
Inc. February 15, 1989. Information on use of fume
suppressants at hard chromium plating operations.
29. Telecon. Cassidy, M., MRI, with Zaki, N., Frederick Gumm
Chemical Company, Inc. February 21, 1989. Information on
use of fume suppressants at hard chromium plating
operations.
30. Technical Data Sheets for Fumetrols 205, 205-T, 201, 208 and
210. M&T Chemicals, Inc. Rahway, New Jersey.
31. Telecon. Cassidy, M., MRI, with Harrison, L., M&T
Chemicals, Inc. February 22, 1989. Information on use of
fume suppressants at hard chromium plating operations.
32. Telecon. Cassidy, M., MRI, with Plyer, G., Frederick Gumm
Chemical Company, Inc. February 24, 1989. Information on
use of fume suppressants at hard chromium plating
operations.
33. Telecon. Cassidy, M., MRI, with Sharpies, T., OMI
International. February 15, 1989. Information on use of
-fume suppressants at hard chromium plating operations.
34. Kama, G., W. Fredrick, D. Millage, and H. Brown. Absolute
Control of Chromic Acid Mist: Investigation of a New
Surface-Active Agent. Reprint from American Industrial
Hygiene Association Quarterly. 1954. p. 4.
35. Chromium Electroplaters Test Report: Greensboro Industrial
Platers, Greensboro, North Carolina. Entropy
Environmentalists, Inc., Research Triangle Park, North
Carolina. Prepared for U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina. EMB
Report 86-CEP-l. March 1986. pp. 2-1 to 2-4.
36. Reference 35, pp. 2-4 to 2-8.
37. Reference 35, p. 3-6.
38. Chromium Electroplaters Test Report: Consolidated Engravers
Corporation, Charlotte, North Carolina. Peer Consultants,
Inc., Rockville, Maryland. Prepared for U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
EMB Report 87-CEP-9. May 1987. p. 4.
39. Reference 38, p. 16.
4-78
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40. Chromium Electroplaters Test Report: Able Machine Company.
Taylors, South Carolina. PEI Associates, Inc., Cincinnati,
Ohio. Prepared for U. S. Environmental Protection Agency,
Research Triangle Park, North Carolina. EMB
Report 86-CEP-3. June 1986. p. 5-1.
41. Reference 40, p. 5-3.
42. Reference 40, p. 2-6.
43. Chromium Electroplaters Test Report: Roll Technology
Corporation, Greenville, South Carolina. Peer Consultants,
Dayton, Ohio. Prepared for U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina. EMB
Report 88-CEP-13. August 1988. pp. 2-1 through 2-2.
44. Reference 43, p. 2-2.
45. Reference 43, pp. 3-5 through 3-12.
46. Reference 7, p. 3.
47. Reference 7, p. 5.
48. Reference 7, pp. 14 and 16.
49. Chromium Electroplaters Test Report: Hard Chrome
Specialists, York, Pennsylvania. Peer Consultants, Inc.,
Dayton, Ohio. Prepared for U. S. 'Environmental Protection
Agency, Research Triangle Park, North Carolina . EMB
Report 89-CEP-15. February 1989. p. 4.
50. Reference 49, p. 6.
51. Reference 49, pp. 18 and 20.
52. Chromium Electroplaters Test Report: Piedmont Industrial
Plating Company, Statesville, North Carolina. Entropy
Environmentalists, Inc., Research Triangle Park, North
Carolina. Prepared for U. S. Environmental Protection
Agency, Research Triangle Park, North Carolina. EMB
Report 86-CEP-04. August 1986. p. 2-1.
53. Reference 52, p. 2-2.
54. Reference 52, pp. 2-4 to 2-6.
55. Reference 52, p. 3-6.
4-79
-------
56. Chromium Electroplaters Test Report: Steel Heddle, Inc.,
Greenville, South Carolina. PEI Associates, Inc.,
Cincinnati, Ohio. Prepared for U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
EMB Report 86-CEP-2. June 1986. pp. 5-1, 5-3, and 5-6.
57. Reference 56, pp. 5-1 and 5-4.
58. Reference 56, p. 2-6.
59. Chromium Electroplaters Test Report: Fusion, Inc., Houston,
Texas. Peer Consultants, Inc., Dayton, Ohio. Prepared for
the U. S. Environmental Protection Agency, Research Triangle
Park, North Carolina. EMB Report 89-CEP-16. May 1989.
p. 4.
60. Reference 59, pp. 5-8.
61. Reference 59, p. 10.
62. Reference 59, pp. 20-21.
63. Chromium Electroplaters Test Report: Automatic Die Casting
Specialties, St. Clair Shores, Michigan. Peer Consultants,
Inc., Dayton, Ohio. Prepared for the U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
EMB Report 88-CEP-ll. April 1988. p. 2-1.
64. Reference 63, pp. 2-1 through 2-2.
65. Reference 63, pp. 3-5 through 3-10.
4-80
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5. MODEL PLANTS AND CONTROL OPTIONS
This chapter describes the model plants arid the control
options for reducing chromium emissions from affected sources.
The model plants portray different combinations of plating tanks
for each type of operation and are representative of both
existing operations and those that are expected to be built in
the future. The model plants are used to evaluate the
environmental, cost, economic, and energy impacts of control
options on the affected sources.
5.1 MODEL PLANTS
Eight model plants were developed to characterize chromium
electroplating and chromic acid anodizing operations that are
capable of plating or anodizing a wide variety of items. The
model plant parameters were developed based on information
obtained from responses to an industry survey, site visits, and
control device vendors. Industry survey responses were obtained
from 120 operations that, combined, operate 215 hard chromium
plating tanks, 102 decorative chromium plating tanks, and
31 chromic acid anodizing tanks. Site visit reports for 17 hard
chromium plating operations, 11 decorative chromium plating
operations, and 3 chromic acid anodizing operations were also
considered in developing the model plants. The model plants
developed include three each (small, medium, and large) for hard
and decorative plating operations and two (small and large) for
anodizing operations. Production rates, operating times, process
equipment, and operating conditions for each model plant are
presented in Tables 5-1 through 5-3.
5-1
-------
5.1.1 Model Plant Sizes
Model plant sizes and process parameters for each model
plant were determined from the data collected through the
industry survey and site visits. Process information obtained
from the industry survey and site visits were compiled into three
data bases that were operation-specific--hard chromium plating,
decorative chromium plating, and chromic acid anodizing.
Frequency distributions of total tank capacity per plant were
developed to assist in selecting representative model plant sizes
for hard and decorative chromium plating operations. These
frequency distributions are shown in Figures 5-1 and 5-2. Three
model plant sizes, representative of small, medium, and large
operations, were selected for both the hard and decorative
chromium plating categories. The total tank capacity cutoff
values selected for hard chromium electroplating operations are
less than 15,100 L (4,000 gal) for a small plant; between 15,100
and 37,850 L (4,000 and 10,000 gal) for a medium plant; and
greater than 37,850 L (10,000 gal) for a large plant. The total
tank capacity cutoff values for decorative chromium
electroplating plants are less than 7,570 L (2,000 gal) for a
small plant, between 7,570 and 30,280 L (2,000 and 8,000 gal) for
a medium plant, and greater than 30,280 L (8,000 gal) for a large
plant.
A frequency distribution was not used to select model plant
sizes for chromic acid anodizing operations. The available data
indicated that chromic acid anodizers could be placed into one of
two distinct size ranges, small and large. Information on total
tank volumes indicated that these volumes range from 378 to
7,570 L (100 to 2,000 gal) at small operations, while tank
volumes at large operations exceed 27,250 L (7,200 gal).
Consequently, two model plants (small and large) were developed
to represent chromic acid anodizing operations.
Cutoffs for total tank capacity were used to divide the
operation-specific data bases into size classifications.
Information on total tank capacity within each size
classification was used to determine typical values for each size
5-2
-------
model plant. In addition, available information on the
dimensions and volumes of individual tanks used for plating and
anodizing were used to develop six model tanks typical of those
used in the industry. These model tanks, along with the total
tank capacity values for the model plants, were used to determine
the number and size of the model tanks used within each model
plant.
5.1.2 Model Plant Production and Process Parameters
5.1.2.1 Hard and Decorative Chromium Plating. Several
different measures were considered for defining model plant
production rates. Surface area plated per year provides a common
basis for comparing production rates because it accounts for
variations in both the number and types of parts plated.
However, respondents to the industry survey indicated that
surface area plated was not generally monitored. Another measure
considered was chromic acid consumption. However, because of the
diverse chromic acid recovery practices, this was also rejected.
An alternative measure of production rate is energy consumption,
or amount of current applied over time (i.e., Ah/yr). This is
generally derivable for hard and decorative chromium plating
operations based on available information. Also, energy
consumption is directly related to the amount of chromium
deposited and plating thickness. Therefore, Ah/yr was chosen as
the basis for establishing production rates for the model hard
and decorative chromium plating plants.
The amount of surface area capable of being plated during
each plating cycle is limited by the size of the plating tank.
Information gathered during the emissions test program was used
to establish typical surface area-to-plating tank volume ratios
(the amount of surface area plated per volume of plating
solution) for each type of operation. Different surface area-to-
volume ratios were developed for each type of operation because
of the variation in the types of parts plated. These ratios were
then used to determine the amount of surface area plated in a
given plating cycle for each type of model operation. For
example, the average surface area-to-volume ratio for hard
5-3
-------
chromium plating tanks tested during the emissions test program
was 0.06 ft2/ft3. For a model hard chromium plating tank with a
capacity of 231 ft , the amount of surface area plated during one
plating cycle is:
231 ft3 x 0.06 ft2/ft3 = 14 ft2
The typical surface area plated during one plating cycle for
the model decorative chromium plating tanks was determined using
an average surface area-to-volume ratio of 0.09 ft2/ft3.
Surface area plating capacities for each model tank and type
of operation, in conjunction with assumed values for the plating
thickness and plating time, were combined with the
electrochemical equivalent for chromium to calculate current
settings for each model tank. The electrochemical equivalent for
chromium at a cathode efficiency of 10 percent is 518 Ah. This
t
means that 518 Ah are required to plate a part with a surface
area of 1 ft2 to an overall plating thickness of 1 mil.
The current settings for the model hard chromium plating
tanks were calculated assuming a plating thickness of 1 mil and a
plating time of 2 hr. For example, for the model tank mentioned
above, the current setting is calculated as follows:
[518 Ah/mil-ft2][1 mil][14 ft2][l/{2 hr)] = 3,625 A
The current settings for the model decorative chromium
plating tanks were calculated assuming a plating thickness of
0.012 mil and a plating time of 0.05 hr.
The values assigned for plating times and plating
thicknesses are typical values, based on information obtained
from plant visits and survey responses. The value used for
cathode efficiency (10 percent) is based on plating bath
efficiencies provided by vendors of hexavalent chromium plating
bath solutions.
The production rate, in terms of Ah/yr, for each model tank
was calculated by multiplying the current settings for the model
5-4
-------
tank by the amount of time the model tank operated within a year.
The model plant production rate, in terms of Ah/yr, was
calculated by summing the individual Ah/yr values for each model
tank used within a model plant. For example, the model small
hard chromium plating plant has one model tank with a capacity of
231 ft3. The tank is in operation 70 percent of the time that
the plant operates (percent time electrodes are energized), and
the plant operates 2,000 hr/yr. As calculated above, this model
tank would have a current setting of 3,625 A. Therefore, the
production rate for the model small hard chromium plating plant
can be calculated as follows:
Ah/yr = (3,625 A) (2,000 hr/yr) (0.70) = 5.0 x 106 Ah/yr"
Similar calculations were performed for the other model hard and
decorative chromium plating plants. These calculations are
presented in Appendix E along with the derivation of the
electrochemical equivalent at 10 percent cathode efficiency.
The values for the percent time electrodes are energized and
for the operating time of the plants were assigned based on
averages of survey responses pertinent to each plant size.
The values assigned for the operating voltage, current
density, and other plating bath parameters (chromic acid
concentration, catalyst concentration, and temperature) are
representative of typical values encountered in the industry.
All of the above parameters were defined for the model plants
because each parameter has an impact on the generation of chromic
acid mist. (For further discussions of the relationship between
production and process parameters and emissions, see Chapter 3,
Section 3.3.1.4.)
5.1.2.2 Chromic Acid Anodizing. Unlike electroplating,
chromic acid anodizing is a voltage-controlled process. Because
of the current fluctuations during the anodizing cycle, the
average current supplied to the tank is difficult to determine,
which, in turn, makes it difficult to use energy input as an
indicator of the production rate. As in the case of the hard and
5-5
-------
decorative plating survey respondents, chromic acid anodizing
respondents indicated that the surface area of the parts was
difficult to quantify. Therefore, this parameter could not be
used as a measure of production rate (and thus, emissions). For
this reason, tank, surface area was selected as the best measure
of emissions because it limits the amount of workload processed,
and the amount of workload processed is related to emission-
generating mechanisms.
Operating times, chromic acid concentrations, temperatures
of the plating solutions, and tank operating voltages for the
model plants were assigned based on averages of survey responses.
5.1.3 Capture System, Control Device, and Stack Parameters
Each model tank is equipped with a ventilation system to
ensure adequate capture of chromic acid mist. Ventilation rates
for the model tanks were established based on guidelines
developed by the American Conference of Governmental Industrial
Hygienists (ACGIH) and the American National Standards Institute
(ANSI).1/2 The type of hood specified for each model tank was
determined based on the ANSI recommendations that lateral hoods
be used on tanks that are less than 107 cm (42 in.), and push-
pull hoods be used on tanks greater than 107 cm (42 in.) wide.3
Minimum ventilation rates for each model tank were determined
based on the minimum control velocity recommended by ANSI for
capture of chromic acid mist (46 m/min [150 ft/min), the
assumption that all model tanks are free-standing (not against a
wall) and not baffled, and the width-to-length ratio of each
model tank.4 Table 5-4 presents the minimum ventilation rates
for hoods used to capture chromic acid mist.
All model tanks equipped with lateral hoods were ventilated
at a rate of 76 m3/min/m2 (250 ft3/min/ft2) of tank surface
area.5 As recommended by ANSI, tanks equipped with push-pull
hoods were ventilated at 50 percent of the value recommended for
lateral hoods with a push air volume less than 1.52 m3/min/m2
(5.0 ft3/min/ft2) of tank surface area.6 Based on the above
criteria, specifications for ventilation hoods and takeoffs for
5-6
-------
the individual model tanks were assigned and are presented in
Table 5-5.
Figures 5-3 through 5-10 present schematics and ductwork
specifications for the various combinations of tanks used to
configure the model plants. Mesh-pad mist eliminators are
designed to handle a maximum airflow rate of 340 m3/min
(12,000 ft3/min), which is considerably lower than the maximum
design airflow rates for packed-bed scrubbers a'nd chevron-blade
mist eliminators. Therefore, two configurations of tank/control
device ventilation arrangements were required to accommodate
these differences. Table 5-6 shows the ventilation
specifications for the control.device configurations used to
treat emissions from the model tanks. In some cases, total"
ventilation rates were rounded to the values representing the gas
flow rates for which factory-assembled units are available.
Parameters for the control devices and stacks are based on
technical data supplied by control device vendors for each of the
applicable control systems and are summarized for each model
plant in Tables 5-7 through 5-9. The control device inlet gas
flow rates presented in these tables are based on the total
ventilation rates for the combinations of model tanks described
in Table 5-6.
5.2 BASELINE CONDITIONS
Because few States have air pollution regulations specific
to chromium, the baseline conditions in this study are not based
on existing State regulations. Rather, the baseline conditions
are based on information about the level of control currently
achieved at existing operations and an estimate of the number of
existing operations nationwide.
Nearly all of the operations use some type of capture system
to comply with Occupational Safety and Health Administration
(OSHA) regulations that limit concentrations of chromic acid and
chromates inside the plant to a ceiling concentration of
0.1 mg/m3 (4 x 10"5 gr/ft3) of air.7 Therefore, emission capture
systems are considered part of the baseline equipment
5-7
-------
configuration for all operations, including those with no control
devices.
5.2.1 Baseline Levels of Control
Baseline control levels were determined based on the
distribution of control techniques currently being applied in the
electroplating industry and the performance test data for these
control techniques presented in Chapter 4.
5.2.1.1 Baseline Control Techniques. Information on the
types of control techniques currently applied in the
electroplating industry were obtained from responses to an
industry survey conducted by EPA in 1987. The survey provided
information on control techniques used at 44 hard chromium
plating operations, 63 decorative chromium plating operations,
and 25 chromic acid anodizing operations. Table 5-10 presents
the resultant baseline conditions. Listed under each class of
operation is the type of control technique applied and the
percentage of total operations applying the given control
technique. For operations that use two different control devices
in series, only the more efficient control device was considered
to be in use.
In the case of hard chromium platers, 30 percent are
uncontrolled, 30 percent are controlled by chevron-blade mist
eliminators, and 40 percent are controlled by packed-bed
scrubbers. Although 3 of the 44 hard chromium plating shops
contacted use a fume suppressant, the use of fume suppressants is
considered to be atypical for purposes of defining baseline
conditions for hard chromium plating operations. In the case of
decorative platers, 15 percent are uncontrolled, 40 percent are
controlled with fume suppressants, 40 percent are controlled with
a combination of fume suppressants and packed-bed scrubbers, and
5 percent are controlled by packed-bed scrubbers. Finally, in
the case of chromic acid anodizers, 40 percent are uncontrolled,
10 percent are controlled by chevron-blade mist eliminators,
30 percent are controlled by fume suppressants, and 20 percent
are controlled by packed-bed scrubbers.
5-
-------
5.2.1.2 Performance Levels at Baseline Conditions. As
highlighted in Chapter 4, each unit tested within a class of
control devices achieved essentially the same outlet emission
concentration. Consequently, the percent reduction achieved by
an individual control device varies depending on the
concentration at the inlet to the control device; units with high
inlet loadings have larger percent reductions than units with low
inlet loadings. Because percent reductions achieved vary
depending on the loading at the inlet of the control unit,
percent reductions assigned at baseline conditions were developed
considering two factors: (1) expected performance levels at
typical inlet conditions for each type of operation, and
(2) recognition that control devices currently in use in the"
electroplating industry are often poorly operated and maintained.
Operation and maintenance problems actually observed during
site visits to numerous facilities included plugged spray
nozzles, plugged and warped packed beds and mesh pads, and beds
in which the packing material had settled to the point where
channeling occurred. At facilities where fume suppressants were
used, makeup additions were frequently not added to the plating
tank in accordance with vendor recommendations. Foam blankets
were allowed to deplete until relatively large holes were evident
in the blanket. Because of concerns that these types of problems
may be widespread among existing facilities, control levels at
baseline conditions were adjusted, as discussed below, to account
for deficiencies in operation and maintenance.
Inlet loadings at the hard chromium plating operations
tested averaged 4.0 mg/dscm (1.7 x 10"3 gr/dscf). At this inlet
loading, the regression equation developed in Chapter 4 predicts
an overall performance efficiency of 99 percent for packed-bed
scrubbers and mesh-pad mist eliminators. However, while the
performance data were gathered at operations where the control
devices were well maintained, actual operating practices in the
industry are generally less than ideal. Therefore, the average
performance level estimated to exist at baseline conditions was
adjusted downward a few percentage points to 97 percent to
5-9
-------
reflect an overall less-than-ideal performance level. The
performance level assigned to chevron-blade mist eliminators
(90 percent) was based on the percent efficiency (95 percent)
calculated by using the average inlet and outlet concentrations
achieved by the three chevron-blade mist eliminators tested and
adjusting this efficiency downward to account for the less-than-
ideal operation and maintenance practices across the industry.
Inlet loadings at the two decorative chromium plating
operations tested averaged 1.2 mg/dscm (5.2 x 10"4 gr/dscf). At
this inlet loading, the regression equation presented in
Chapter 4 predicts a percent reduction of 97 percent for packed-
bed scrubbers and mesh-pad mist eliminators. However, the
percent reduction assigned to the baseline condition was lowered
to 95 percent, again to account for less-than-ideal operation and
maintenance practices. Percent reduction demonstrated by
chemical fume suppressants during the test program exceeded
99 percent. However, as stated previously, vendor maintenance
requirements are rarely met in practice. Therefore, the percent
reduction assumed at baseline conditions was lowered to
97 percent.
No test data were available for chromic acid anodizing
operations. The inlet loadings for anodizing operations are more
similar to those observed in decorative chromium plating than
those in hard chromium plating operations. Thus, the performance
levels assigned to the control techniques applied to anodizing
operations were identical to those established for decorative
chromium plating operations. The only exception is the control
level assigned to chevron-blade mist eliminators, which was
assumed to be the same for anodizing operations as for hard
chromium plating operations.
5.2.2 Number of Operations Nationwide
Table 5-11 presents estimates by size of the numbers of hard
and decorative chromium plating and chromic acid anodizing
operations nationwide. The total number of each type of
operation was obtained from information published in the 1982
Census of Manufacturers--Selected Metalworking Operations and
5-10
-------
Finishers' Management Media/Market Bulletin.8'9 Differentiation
by size (small, medium, and large) is based on the size
distribution obtained from the EPA industry survey of 44 hard and
63 decorative plating operations. The numbers of small and large
operations for chromic acid anodizing are based on the
assumptions that all captive shops that manufacture aerospace
parts are large and that all job shops and captive shops that
manufacture electronic parts are small. As shown in Table 5-11,
70 percent of the total number of hard chromium plating
operations are small, 20 percent are medium, and 10 percent are
large; while 80 percent of the total number of decorative
chromium plating operations are small, 15 percent are medium, and
5 percent are large. In the case of chromic acid anodizers, -
75 percent of the total number are small and 25 percent are
large.
5.3 CONTROL OPTIONS
5.3.1 General
Table 5-12 presents control options being considered for
chromium plating and chromic acid anodizing operations. Each
control option represents a different level of emission control.
The level of control assigned to each control technique is based
on the percent reduction achievable by well-maintained units at
average inlet loadings for each type of operation.
For each type of operation, Option I is the "no action" or
baseline option. The "no action" option reflects the level of
control achieved at existing operations in the absence of further
regulation.
5.3.2 Hard Chromium Plating
Control Option I (no action) for hard chromium plating
operations reflects the baseline condition described in
Section 5.2. The baseline condition assumes that 30 percent of
all existing operations are uncontrolled, 30 percent are
controlled by chevron-blade mist eliminators that reduce
uncontrolled emissions by 90 percent, and 40 percent are
controlled by packed-bed scrubbers that reduce uncontrolled
emissions by 97 percent. Control Option II is based on the use
5-11
-------
of chevron-blade mist eliminators that reduce uncontrolled
emissions by 95 percent. Control Option III is based on the use
of packed-bed scrubbers or mesh-pad mist eliminators that reduce
uncontrolled emissions by 99 percent. The percent reductions
assigned to each control option are based on the control levels
determined in Section 5.2.1.2 for well-maintained units.
5.3.3 Decorative Chromium Plating
Control Option I (no action) for decorative chromium plating
operations is based on the assumption that approximately
15 percent of all existing operations are uncontrolled,
40 percent are controlled by fume suppressants that reduce
uncontrolled emissions by 97 percent, 40 percent are controlled
by a combination of fume suppressants and packed-bed scrubbers
that reduces uncontrolled emissions by 97 percent, and 5 percent
are controlled by packed-bed scrubbers that reduce uncontrolled
emissions by 95 percent. Control Option II is based on the use
of packed-bed scrubbers or mesh-pad mist eliminators that reduce
uncontrolled emissions by 97 percent. Control Option III is
based on the use of chemical fume suppressants, applied in
accordance with vendor recommendations, that reduce uncontrolled
emissions by 99.5 percent. The percent reduction assigned to
Control Options II and III are based on the control levels
determined in Section 5.2.1.2 for well-maintained units. Control
Option IV, the most stringent option for decorative chromium
plating operations, is based on the use of the trivalent chromium
plating process instead of the hexavalent chromium plating
process. The use of this process would reduce hexavalent
chromium emissions by 100 percent. However, there are some
application problems with the trivalent chromium process that
might limit its use at some decorative chromium plating
operations. For a discussion of these problems, refer to
Chapter 3, Section 3.2.6.1.
5.3.4 Chromic Acid Anodizing
Control Option I (no action) for chromic acid anodizing is
based on the assumption that approximately 40 percent of all
existing operations are uncontrolled, 10 percent are controlled
5-12
-------
by chevron-blade mist eliminators that reduce uncontrolled
emissions by 90 percent, 30 percent are controlled by fume
suppressants that reduce uncontrolled emissions by 97 percent,
and 20 percent are controlled by packed-bed scrubbers that reduce
uncontrolled emissions by 95 percent. Control Option II is based
on the use of packed-bed scrubbers or mesh-pad mist eliminators
that reduce uncontrolled emission by 97 percent. Control
Option III, the most stringent option, is based on the use of
chemical fume suppressants, applied in accordance with vendor
recommendations, that reduce uncontrolled emissions by
99.5 percent. The percent reductions assigned for Control
Options II and III are based on the percent reductions calculated
in Section 5.2.1.2 for well-maintained decorative chromium
plating operations. The percent reductions are based on
decorative chromium plating data because no data were available
for chromic acid anodizing operations. The expected inlet
concentrations for chromic acid anodizing operations should be
more similar to the inlet concentrations measured at decorative
chromium plating operations than those measured at hard chromium
plating operations.
5.3.5 Impact Assessment
For purposes of assessing energy and cost impacts, some
assumptions were made regarding chevron-blade mist eliminator and
packed-bed scrubber designs. Information provided in the
industry survey was not sufficient to predict the prevalence of
chevron-blade mist eliminators with a double set of blades vs.
those with a single set of blades or the prevalence of double
packed-bed scrubbers vs. single packed-bed scrubbers. A chevron-
blade mist eliminator with a single set of blades was assumed for
baseline purposes (existing level of control), and a chevron-
blade mist eliminator with a double set of blades was assumed for
the control options. A single packed-bed scrubber was assumed
for the energy and cost impacts associated with baseline and the
control options.
5-13
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5-16
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plating model plants (Configurations 1 and 2).
5-18
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TABLE 5-4. MINIMUM VENTILATION RATES FOR VENTILATION
HOODS USED TO CAPTURE EMISSIONS OF CHROMIC ACID
MIST FROM CHROMIUM PLATING AND CHROMIC ACID
ANODIZING TANKSa'5
Hood along one side or two parallel sides of
free-standing tank not against wall or baffled
Tank width-to-
length ratio
0.0-0.09
0.1-0.24
0.25-0.49
0.5-0.99
1.0-2.0
Lateral hoods,
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m /min/m
(ft3/mia/ft2)b c
69 (225)
76 (250)
76 (250)
76 (250)
76 (250)
Push-pull hoods,
"V 9
m /min/m
(fP/min/ft2)
35 (115)
38 (125)
38 (125)
38 (125)
38 (125)
aVentilation rates are based on the minimum control velocity of 46 m/min (150 ft/min) recommended for
chromic acid mist.
kpor lateral hoods along centerline or two parallel sides of tank, tank width-to-length ratio equals tank width
divided by 2.
cAlthough a ventilation rate of 76 rrr/min/m2 (250 ft3/min/fr) may not produce a control velocity of 46 m/min
(150 ft/min) at all aspect ratios, the ventilation rate is considered adequate for control.
5-2!
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-------
TABLE 5-6
CONTROL DEVICE VENTILATION SPECIFICATIONS
FOR MODEL PLANTS
Model tanks
Model plant No. Tank dimensions (1, w, d), m (ft)
Total ventilation
rate per control
device,
m /min (fr/min)
Figure for plan
view and
ductwork
specification
Scrubbers or chevron-blade mist eliminators
Hard plating
Small*
Medium (Configuration l)a
Large (Configuration 1)
Decorative plating
Small8
Medium0
Large (Configuration 1)
1 3.6,1.1,1.8(12.0,3.5,6.0)
1 1.2, 1.2, 3.0 (4.0, 4.0, 10.0)
2 3.6, 1.2, 1.8 (12.0, 4.0, 6.0)
1 7.6, 0.9, 1.8 (25.0, 3.0, 6.0)
2 1.2,1.2,3.0(4.0,4.0,10.0)
4 3.6, 1.2, 1.8 (12.0, 4.0, 6.0)
2 7.6, 0.9, 1.8 (25.0, 3.0, 6.0)
1 3.6, 1.1, 1.8 (12.0, 3.5, 6.0)
2 3.6, 1.1, 1.8 (12.0, 3.5, 6.0)
5 3.6, 1.8, 2.7 (12.0, 6.0, 9.0)
340 (12,000) Figure 5-3
990 (35,000) Figure 5-4
2 @ 990 (35,000) Figure 5-4
340 (12,000) Figure 5-3
2 @ 340 (12,000) Figure 5-3
283 (10,000) Figure 5-5a
2 @ 510 (18,000) Figure 5-5b
Anodizing
Small2
Large (Configuration l)a
Mesh-pad mist eliminators
1 3.6, 1.1, 1.8 (12.0, 3.5, 6.0)
2 9.1, 1.5, 2.7 (30.0, 5.0,. 9.0)
340 (12,000) Figure 5-3
1,130 (40,000) Figure 5-6
Hard plating
Smalla
Medium (Configuration 2)e
Large (Configuration 2)
1 3.6, 1.1, 1.8 (12.0,3.5, 6.0)
1 1.2, 1.2, 3.0 (4.0, 4.0, 10.0)
2 3.6,1.2,1.8(12.0,4.0,6.0)
1 7.6,0.9,1.8(25.0,3.0,6.0)
2 1.2,1.2,3.0(4.0,4.0,10.0)
4 3.6, 1.2, 1.8 (12.0, 4.0,6.0)
2 7.6, 0.9, 1.8 (25.0, 3.0, 6.0)
340 (12,000)
170 (6,000)
227 (8,000)
2 @ 283 (10,000)
2 @ 170 (6,000)
2 @ 227 (8,000)
4 @ 283 (10,000)
Figure 5-3
Figure 5-7
Figure 5-8
Figure 5-9
Figure 5-7
Figure 5-8
Figure 5-9
Decorative plating
Small3
Medium0
Large (Configuration 2)8
Anodizing
Small"
Large (Configuration 2)"
1 3.6, 1.1, 1.8 (12.0, 3.5, 6.0)
2 3.6, 1.1, 1.8 (12.0, 3.5, 6.0)
5 3.6, 1.8, 2.7 (12.0, 6.0, 9.0)
1 3.6,1.1,1.8(12.0,3.5,6.0)
2 9.1, 1.5, 2.7 (30.0, 5.0, 9.0)
340 (12,000) Figure 5-3
2 @ 340 (12,000) Figure 5-3
5 @ 283 (10,000) Figure 5-5a
340 (12,000)
4 @ 283 (10,000)
Figure 5-3
Figure 5-10
aAll tanks are vented to one control device.
''Two control devices are used to control emissions from all tanks. Each control device is used to control four tanks.
°Each of the tanks is vented to a separate control device.
^One tank is vented to one control device, and two tanks each are vented to a second and a third control device.
eFour control devices are used to control emissions from the plating tanks.
Eight control devices are used to control emissions from the plating tanks.
SEach of the five tanks is vented to a separate control device.
Each plating tank is controlled by two devices.
5-30
-------
TABLE 5-7.
CONTROL DEVICE AND STACK PARAMETERS FOR THE MODEL
HARD CHROMIUM ELECTROPLATING PLANTS
Type
Hard
' I.
n.
of operation/control device
chromium plating
Packed-bed scrubbers and chevron-blade mist eliminators
A. Control device parameters
No. of control devices
Inlet gas flow rate, m3/min (ft3/min)*
Inlet gas temperature, °C (°F)
Inlet gas moisture, percent
1 . Single packed-bed scrubber, AP, kPa (In. w.c)
Liquid-to-gas ratio, JL/min/ 1,000 rrr/min
(gal/min/l.OOOr^/min)
2. Double packed-bed scrubber, AP, kPa fin. w.c.)
Liquid to gas ratio, IV mi n/ 1,000 m /min
(gaymin/l,000ft3/min)
3. Chevron-blade mist eliminators with single set of
blades, A?, kPa Cm. w.c.)
4. Chevron-blade mist eliminators with double set
of blades, AP, kPa Cm. w.c.)
B. Suck parameters
No of stacks
Height, m (ft)b
Diameter, m (ft)
Temperature, °C (°F)
Moisture, percent
Gas flow rate, m /min (fr /min)
Gas velocity, m/min (ft/ min)
Mesh-pad mist eliminators
A. Control device parameters
No. of control devices
Inlet gas flow rate, m/min (ft3/min)*
Inlet gas temperature, °C (°F)
Inlet gas moisture, percent
Mesh-pad eliminator, AP, kPa Cm. w.c.)
B. Stack parameters
No. of stacks
Height, m (ft)b
Diameter, m (ft)
Temperature, "C ("F)
Moisture, percent
Gas flow rate, m/min (fn/min)
Gas velocity, m/min (ft/min)
Small
1
340 (12,000)
27 (80)
2
0.5(2)
400(3)
0.75 (3)
800(6)
0.19(0.75)
0.5®
1
9.1 (30)
0 7 (2.3)
27 (80)
2
340 (12,000)
910 (3,000)
1
340 (12,000)
27 (80)
2
0.75 (3.0)
1
9.1 (30)
0.7(2.3)
27 (80)
2
340 (12,000)
910 (3,000)
Plant size
Medium
1
. 990 (35,000)
27 (80)
2
0.5(2)
400(3)
0.75 (3)
800(6)
0.19 (0.75)
0.5(2)
1
9.1 (30)
1.1(3.8)
27 (80)
2
990 (35,000)
910 (3,000)
4
170 (6,000)
227 (8,000)
2 @ 283 (10,000)
27 (80)
2
0.75 (3.0)
4
9.1 (30)
0.5(1.5)
0.5(1.8)
2 @ 0.6 (2.1)
27 (80)
2
170 (6,000)
227 (8,000)
2 @ 283 (10,000)
910 (3,000)
Large
2
2 @ 990 (35,000)
27 (80)
2
0.5(2)
400(3)
0.75 (3)
800(6)
0.19(0.75)
0.5(2)
2
9.1 (30)
2@ 1.1 (3.8)
27 (80)
2
2 @ 990 (35,000)
910 (3,000)
8
2 @ 170 (6,000)
2 @ 227 (8,000)
4 @ 283 (10,000)
27 (80)
2
0.75 (3.0)
8
9.1 (30)
2 @0.5 (1.5)
2 @0.5 (1.8)
4 @ 0.6 (2.1)
27 (80)
2
2 @ 170 (6,000)
2 @ 227 (8,000)
4 @ 283 (10,000)
910 (3,000)
'Ventilation rates were rounded to the gas flow rates for which factory-assembled control devices are available.
Stack height is the distance from ground level to the point of discharge.
5-31
-------
TABLE 5-8. CONTROL DEVICE AND STACK PARAMETERS FOR THE MODEL
DECORATIVE CHROMIUM ELECTROPLATING PLANTS
Type
of operation/control device
Small
Plant size
Medium
Large
Decorative chromium plating
I
n
Packed-bed scrubbers and chevron-blade mist eliminators
A. Control device parameters
No of control devices
Inlet gas flow rate, nr/min (rr/min)a
Inlet gas temperature, °C (°F)
Inlet gas moisture, percent
1. Single packed-bed scrubber, iP, kPa (in. w.c)
Liquid-to-gas ratio, J_/min/ 1,000 m/min
(gal/min/l.OOOrWmin)
2. Double packed-bed scrubber, AP, kPa On. w.c.)
Liquid to gas ratio, JJmin/1, 000 m /min
(gal/mirV 1 ,000 fH/min)
3. Chevron-blade mist eliminator with single set of
blades, &P, kPa fin. w.c.)
4. Chevron-blade mist eliminator with double set of
blades, iP, kPa (in. w.c.)
B. Stack parameters
No. of stacks
- Height, m (ft)b
Diameter, m (ft)
Temperature, °C (°F)
Moisture, percent
Gas flow rate, m /min (ft /mm)
Gas velocity, m/min (ft/min)
Mesh-pad mist eliminators
A. Control device parameters
No. of control devices
Inlet gas flow rate, nr/min (ft3/min)a
Inlet gas temperature, °C (°F)
InJet gas moisture, percent
Mesh-pad mist eliminator, ^P, kPa 0". w.c.)
B. Suck parameters
No. of stacks
Height, m (ft)b
Diameter, m (ft)
Temperature, °C (°F)
Moisture, percent
Gas flow rate, m/min (fr /min)
Gas velocity, m/min (ft/min)
1
340 (12,000)
27 (80)
2
0.5(2)
400(3)
0.75 (?)
800(6)
0.19(0.75)
0.5(2)
1
9.1 (30)
0.7 (2.3)
27 (80)
2
340 (12,000)
910 (3,000)
1
340 (12,000)
27 (80)
2
0.75 (3.0)
1
9.1 (30)
0.7(2.3)
27 (80)
2
340 (12,000)
910 (3,000)
2
2 @ 340 (12,000)
27 (80)
2
0.5(2)
400(3)
0.75 (3)
800(6)
0.19 (0.75)
0.5(2)
2
9.1 (30)
2 @ 0.7 (2.3)
27 (80)
2
2 @ 340 (12,000)
910 (3,000)
2
2 @ 340 (12,000)
27 (80)
2
0.75(3.0)
2
9.1 (30)
2 @ 0.7 (2.3)
27 (80)
2
2 @ 340 (12,000)
910 (3,000)
3
280 (10,000)
2 ©510(18,000)
27 (80)
2
0.5(2)
400(3)
0.75 (3)
800(6)
0.19 (0.75)
0.5(2)
3
9.1 (30)
0.6(2.1)
2 @0.8 (2.8)
27 (80)
2
280 (10,000)
2 ©510(18,000)
910(3,000)
5
5 @ 283 (10,000)
27 (80)
2
0.75 (3.0)
5
9.1 (30)
5 @ 0.6 (2-1)
27 (80)
2
5 @ 283 (10,000)
910 (3,000)
ffl. Fume suppressants
Annual usage, kg/yr or L/yr (lb/yr or gal/yr)
17 or 120
(37 or 32)
67 or 480
(148 or 128)
295 or 2,080
(650 or 550)
aVentilation rates were rounded to the gas flow rates for which factory-assembled control devices are available.
bStack height is the distance from ground level to the point of discharge.
5-32
-------
TABLE 5-9.
CONTROL DEVICE AND STACK PARAMETERS FOR THE MODEL
CHROMIC ACID ANODIZING PLANTS
Flint size
Type of operation/control device
Small
Large
Chromic acid anodizing
I. Packed-bed scrubbers and chevron-blade mist eliminators
A. Control device parameters
No. of control devices
Inlet gas flow rate, m/min (ft'/min)*
Inlet gas temperature, "C (°F)
Inlet gas moisture, percent
1. Single packed-bed scrubber, iP, kPa Cm. w.c)
Liquid-to-gas ratio. L/min/1,000 nr/min
(gal/min/1,000 fP/roin)
2. Double packed-bed scrubber, A?, kPa (in. w.c.)
Liquid to gas ratio. L/min/1,000 m/min
(gal/min/l.OOOfr/niin)
3. Chevron-blade mist eliminator with single set of bUdes, iP, kPa
(in. w.c.)
4. Chevron-blade mist eliminator with double set of blades, iP, kPa
(in. w.c.)
B. Stack parameters
No. of stacks
Height, m (ft)b
Diameter, m (ft)
Temperature, °C (°F)
Moisture, percent
Gas flow rate, m /min (ft /min)
Gas velocity, m/min (ft/min)
II. Mesh-pad mist eliminators
1
340 (12,000)
27 (80)
2
0.5(2)
400(3)
0.75 (3)
800(6)
0.19(0.75)
0-5(2)
9.1 (30)
0.7(2.3)
27 (80)
340 (12,000)
910 (3,000)
1
1,130(40,000)
27 (80)
2
0.5(2)
400(3)
0.75 (3)
800(6)
0.19(0.75)
0.5(2)
1
9.1 (30)
1.2(4.1)
27 (80)
1,130(40,000)
910 (3,000)
A. Control device parameters
No. of control devices
Inlet gas flow rate, m/min (fP/min)*
Inlet gas temperature °C (°F)
Inlet gas moisture, percent
Mesh-pad mist eliminator, A?, kPa (in. w.c )
B. Suck parameters
No. of stacks
Height, m (ft)b
Diameter, m (ft)
Temperature, °C (°F)
Moisture, percent
Gas flow rate, m/min (fr/min)
Gas velocity, m/min (ft/min)
ID. Fume suppressants
Annual usage, kg/yr
1
340 (12,000)
27(80)
2
0.75(3.0)
1
9.1(30)
0.7(2.3)
27 (80)
2
340 (12,000)
910 (3,000)
9.0 (20)
4
4 @ 283 (10,000)
27 (80)
2
0.75(3.0)
4
9.1 (30)
4@0.6 (2.1)
27 (80)
2
4 @ 283 (10,000)
910(3,000)
72(160)
'Ventilation rates were rounded to the gas flow rates for which factory-assembled control devices are available.
"Stack height is the distance from ground level to the point of discharge.
5-33
-------
TABLE 5-10. BASELINE CONTROL LEVELS FOR CHROMIUM PLATING
AND CHROMIC ACID ANODIZING OPERATIONS
Associated
level of
control,
Percent of percent
total Cr
Operation/control technique operations reduction
Hard plating
Uncontrolled 30 0
Chevron-blade mist eliminator with 30 90
a single set of blades
Packed-bed scrubber 40 97
Total 100
Decorative plating
Uncontrolled 15 0
Fume suppressant 40 97
Fume suppressant combined with a 40 97
packed-bed scrubber
Packed-bed scrubber 5 95
Total 100
Chromic acid anodizing
Uncontrolled 40 0
Chevron-blade mist eliminator with 10 90
a single set of blades
Fume suppressant 30 97
Packed-bed scrubber 20 95
Total 100
5-34
-------
TABLE 5-11. NUMBER OF OPERATIONS NATIONWIDE
No. of Percentage
operations of total
Type of operation nationwide (by type)
1. Hard chromium plating
Small 1,080 70
Medium 310 20
Large 150 LQ
Total 1,540 100
2. Decorative chromium plating
Small 2,240 80
Medium 420 15
Large 140 5
Total 2,800 100
3. Chromic acid anodizing
Small 515 75
Large 165 25
Total 680 100
5-35
-------
TABLE 5-12. SUMMARY OF CONTROL OPTIONS
Type of operation/
Control option
Control technique
Hard chromium plating
Option I (no action)3
Option IIb
Option mb
Decorative chromium plating
Option I (no action)3
Option nb
Option IIlb
Option IVb
Chromic acid anodizing
Option I (no action)3
Option Hb
Option fflb
Existing (baseline level of control)
• 30 percent of operations uncontrolled
• 30 percent of operations controlled by chevron-blade mist
eliminators that reduce uncontrolled emissions by 90 percent
• 40 percent of operations controlled by packed-bed scrubbers that
reduce uncontrolled emissions by 97 percent
Chevron-blade mist eliminators that reduce uncontrolled emissions by
95 percent
Packed-bed scrubbers or mesh-pad mist eliminators that reduce
uncontrolled emissions by 99 percent
Existing (baseline) level of control
• 15 percent of operations uncontrolled
• 40 percent of operations controlled by chemical fume suppressants
that reduce uncontrolled emissions by 97 percent
• 40 percent of operations controlled by a combination of chemical
fume suppressants and packed-bed scrubbers that reduces
uncontrolled emissions by 97 percent
• 5 percent of operations controlled by packed-bed scrubbers that
reduce uncontrolled emissions by 95 percent
Packed-bed scrubbers or mesh-pad mist eliminators that reduce
uncontrolled emissions by 97 percent
Chemical fume suppressants applied in accordance with vendor
recommendations. Uncontrolled emissions reduced by 99.5 percent
Trivalent chromium plating processes that reduce hexavalent chromium
emissions by 100 percent (technology forcing)
Existing (baseline) level of control
• 40 percent of operations uncontrolled
• 30 percent of operations controlled by chemical fume suppressants
that reduce uncontrolled emissions by 97 percent
• 10 percent of operations controlled by chevron-blade mist
eliminators that reduce uncontrolled emissions by 90 percent
• 20 percent of operations controlled by packed-bed scrubbers that
reduce uncontrolled emissions by 95 percent
Packed-bed scrubbers or mesh-pad mist eliminators that reduce
uncontrolled emissions by 97 percent
Chemical fume suppressants applied in accordance with vendor
recommendations. Uncontrolled emissions reduced by 99.5 percent
3 The emission reductions presented here are based on the application of control techniques under representative
baseline conditions, recognizing that control devices currently in use are often poorly operated and
maintained.
The emission reductions presented here reflect the application of control techniques under good operation and
maintenance conditions.
5-36
-------
5.4 REFERENCES FOR CHAPTER 5
l. Industrial Ventilation: A Manual of Recommended Practice.
American Conference of Governmental Industrial Hygienists.
19th edition. 1986. pp. 5-68 to 5-70.
2. American National Standard Practices for Ventilation and
Operation of Open-Surface Tanks. ANSI 29.1-1977. New York,
American National Standards Institute, Inc. 1977.
3. Reference 2, p. 13.
4. Reference 3, pp. 13 and 22.
5. Reference 3, pp. 13 and 14.
6. Reference 3, pp. 13 and 15.
7. U.S. Department of Labor. Code of Federal Regulations.
29 CFR 1910.1000. Washington, B.C. July 1, 1986. p. 659.
8. U.S. Department of Commerce, Bureau of Census. Census of
Manufacturers--Selected Metalworking Operations.
Washington, D.C. Publication No. MC82-S-8. September 1985.
9. Finishers' Management Media/Market Bulletin. Metal
Finishing Job Shop Industry Profile .... 1985/86.
Glenview, Illinois. 1986. p. 2
5-37
-------
6. ENVIRONMENTAL IMPACTS
6.1 INTRODUCTION
The purpose of this chapter is to present the air pollution,
energy, water pollution, and solid waste impacts associated with
the control options for reducing hexavalent chromium emissions
from hard and decorative chromium electroplating and chromic acid
anodizing operations. All impacts are based on the model plant
parameters and control options presented in Chapter 5 and on
industry profile data and growth projections presented in
v
Chapter 8. Table 6-1 summarizes the control options upon which
the environmental impacts are based. Incremental impacts are
calculated by comparing the projected nationwide impacts under
Option II, Option III, and Option IV to the impacts at baseline
conditions (Option I). Control Option I represents the existing
level of control currently being achieved by chromium plating and
chromic acid anodizing operations in the absence of a NESHAP for
chromium.
6.2 AIR POLLUTION IMPACTS
This section presents estimates of nationwide hexavalent
chromium emissions under each control option for hard and
decorative plating and chromic acid anodizing operations.
Nationwide emission estimates for each control option are based
on estimates of annual uncontrolled emissions ascribed to each
model plant, estimates of the number of chromium plating or
chromic acid anodizing operations within each model plant size
category, and the control levels associated with the control
option. For example, there are an estimated 1,080 small hard
chromium plating operations nationwide. Under Option I (no
action), 30 percent (324 operations) are uncontrolled, 30 percent
6-1
-------
(324 operations) are controlled by chevron-blade mist eliminators
with an average emission reduction of 90 percent, and 40 percent
(432 operations) are controlled by packed-bed scrubbers with an
average emission reduction of. 97 percent. The estimated
nationwide chromium emission rate for small hard chromium plating
operations can be calculated by multiplying the number of
operations at each control level by the annual uncontrolled small
model plant emission rate of 0.05 Mg/yr (0.055 ton/yr), as
follows:
(324)(0.05 Mg/yr) = 16 Mg/yr (18 tons/yr)
(324)(0.05 Mg/yr)(1 - 0.90) = 1.6 Mg/yr (1.8 tons/yr)
(432)(0.05 Mg/yr)(1 - 0.97) = 0.65 Mg/yr (0.71 ton/yr)
Total emissions for small operations are 18 Mg/yr
(20 tons/yr). Emissions were calculated in this manner for each
of the model plant sizes for hard and decorative chromium plating
and chromic acid anodizing operations. The total nationwide
hexavalent chromium emission rate for each type of operation
under each control option is the sum of the nationwide totals for
each model plant size.
6.2.1 Hard Chromium Electroplating
6.2.1.1 Nationwide Emissions. Nationwide hexavalent
chromium emission estimates for each control option are presented
in Table 6-2. The total nationwide emission rate for all hard
chromium plating operations under Option I (no action) is
145 Mg/yr (160 tons/yr), which is the sum of the nationwide
totals for each model plant size.
Control Option II is based on the use of a chevron-blade
mist eliminator that reduces uncontrolled emissions by
95 percent. Application of Option II would reduce emissions by
95 percent for the 30 percent of operations that are uncontrolled
under Option I and would increase the control level from 90 to
95 percent for the 30 percent of operations that currently use a
chevron-blade mist eliminator. This increased level of control
is achievable with good operation and maintenance practices.
Emissions from the 40 percent of operations that are controlled
by packed-bed scrubbers with control efficiencies greater than
6-2
-------
95 percent would remain the same. Total nationwide chromium
emissions associated with Option II are 18 Mg/yr (20 tons/yr).
Emission estimates associated with Option III for hard
chromium plating operations are based on the use of a packed-bed
scrubber or a mesh-pad mist eliminator that reduces uncontrolled
emissions by 99 percent. Application of Option III would reduce
emissions by 99 percent for the 30 percent of operations that are
uncontrolled under Option I and increase the control level for
the 30 percent of operations that currently use a chevron-blade
mist eliminator from 90 to 99 percent. Implementation of
Option III would also increase the control level from 97 to
99 percent at the 40 percent of operations that currently used
packed-bed scrubbers. This improved level of control for packed-
bed scrubbers is achievable with improved operating and
maintenance practices. Total nationwide chromium emissions
associated with Option III are 4.2 Mg/yr (4.7 tons/yr).
6.2.1.2 Emission Reductions. Table 6-3 presents nationwide
emission reductions for the control options for hard chromium
electroplating. Control levels associated with Option II would
reduce nationwide emissions over Option I by 88 percent, or
127 Mg/yr (140 tons/yr). The average control level associated
with Option III would reduce nationwide emissions over Option I
by 97 percent or 141 Mg/yr (155 tons/yr) and reduce nationwide
emissions over Option II by 76 percent, or 14 Mg/yr (15 tons/yr).
6.2.2 Decorative Chromium Electroplating
6.2.2.1 Nationwide Hexavalent Chromium Emissions.
Nationwide hexavalent chromium emission estimates for each
control option are presented in Table 6-4. Under Option I, about
15 percent of the operations are uncontrolled, 40 percent are
controlled by fume suppressants that reduce uncontrolled
emissions by 97 percent, 40 percent are controlled by a
combination of fume suppressants and packed-bed scrubbers that
reduces uncontrolled emissions by 97 percent, and 5 percent are
controlled by packed-bed scrubbers that reduce uncontrolled
emissions by 95 percent. Total nationwide chromium emissions
under Option I are 10 Mg/yr (11 tons/yr).
6-3
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Control Option II is based on the use of a packed-bed
scrubber or a mesh-pad mist eliminator to reduce uncontrolled
emissions by 97 percent. For the 15 percent of operations that
are uncontrolled under Option I, application of Option II would
reduce emissions by 97 percent. Emissions from the 40 percent of
operations controlled by fume suppressants and the 40 percent of
operations controlled by a combination of fume suppressants arid
packed-bed scrubbers would remain the same. For the 5 percent, of
operations that are controlled by packed-bed scrubbers, Option II
would increase the control level from 95 percent to 97 percent.
This improved level of control for packed-bed scrubbers is
achievable with improved operating and maintenance practices.
Total nationwide chromium emissions associated with Option II are
1.7 Mg/yr (1.9 tons/yr).
Control Option III is based on the proper addition and use
of fume suppressants. When vendor directions are strictly
observed, this control technique will achieve 99.5 percent
control, significantly improving upon the control level typically
achieved when vendor recommendations are not strictly followed.
Implementation of Option III would reduce emissions by
99.5 percent for the 15 percent of the operations that are
uncontrolled under Option I, increase the control level at the
5 percent of operations that currently use packed-bed scrubbers,
and increase the level of control from 97 percent to 99.5 percent
for the 40 percent of operations that currently use fume
suppressants and the 40 percent of operations that currently use
a combination of fume suppressants and packed-bed scrubbers.
Nationwide chromium emissions associated with Option III are
0.29 Mg/yr (0.32 ton/yr).
Control Option IV is based on the substitution of a
trivalent chromium plating bath for a conventional hexavalent
chromium plating bath. This is a technology-forcing option.
Because there is no hexavalent chromium associated with trivalent
processes, implementation of Option IV would eliminate hexavalent
chromium emissions, resulting in a nationwide hexavalent chromium
emissions level of zero.
6-4
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6.2.2.2 Emission Reductions. Table 6-5 presents nationwide
emission reductions for the control options for decorative
chromium electroplating. The control level associated with
Option II would reduce nationwide emissions over Option I by
83 percent or about 8.4 Mg/yr (9.2 tons/yr). The control level
associated with Option III would reduce nationwide emissions over
Option I and Option II by 97 and 83 percent, or 9.8 Mg/yr
(11 tons/yr) and 1.4 Mg/yr (1.6 tons/yr), respectively. The
control level associated with Option IV would reduce nationwide
emissions over Option I, Option II, and Option III by
100 percent, or 10 Mg/yr (11 tons/yr), 1.7 Mg/yr (1.9 tons/yr),
and 0.29 Mg/yr (0.32 ton/yr), respectively.
6.2.3 Chromic Acid Anodizing
6.2.3.1 Nationwide Hexavalent Chromium Emissions.
Nationwide hexavalent chromium emission estimates for each
control option are presented in Table 6-6. Under Option I, about
40 percent of the operations are uncontrolled, 10 percent are
controlled by chevron-blade mist eliminators that reduce
uncontrolled emissions by 90 percent, 20 percent are controlled
by packed-bed scrubbers that reduce uncontrolled emissions by
95 percent, and 30 percent are controlled by fume suppressants
that reduce uncontrolled emissions by 97 percent. Total
nationwide chromium emission rates from chromic acid anodizing
operations under Option I are about 3.6 Mg/yr (3.9 tons/yr).
Control Option II is based on the use of a packed-bed
scrubber or a mesh-pad mist eliminator that reduces uncontrolled
emissions by 97 percent. Under Option II, emissions from the
40 percent of operations that are uncontrolled under Option I
would be reduced by 97 percent. The control level at the
10 percent of operations that are currently controlled by
chevron-blade mist eliminators at a level of 90 percent would be
increased by 7 percent. Control Option II would increase the
control level from 95 to 97 percent at the 20 percent of
operations that are controlled by packed-bed scrubbers under
Option I. This improved level of control for packed-bed
scrubbers is achievable with improved operating and maintenance
6-5
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practices. Emissions from the 30 percent of operations that use
fume suppressants and already have an emission reduction of
97 percent would remain the same. Total nationwide chromium
emissions associated with Option II are 0.25 Mg/yr (0.27 ton/yr).
Control Option III is based on the use of fume suppressants
consistent with vendor recommendations. Implementation of
Option III would reduce emissions by 99.5 percent for the
40 percent of the operations that are uncontrolled under
Option I. The levels of control would be increased by
9.5 percent at the 10 percent of operations that currently use
chevron-blade mist eliminators and 4.5 percent at the 20 percent
of operations that use packed-bed scrubbers. Control Option III
would increase the level of control from 97 percent to
99.5 percent for the 30 percent of operations that currently use
fume suppressants. When vendor recommendations are strictly
observed, this control technique will achieve a 99.5 percent
emissions reduction, improving upon the efficiencies typically
achieved when vendor recommendations are not followed.
Nationwide chromium emissions associated with Option III are
0.04 Mg/yr (0.05 ton/yr).
6.2.3.2 Emission Reductions. Table 6-7 presents nationwide
emission reductions for the control options. The control level
associated with Option II would reduce nationwide emissions over
Option I by 93 percent, or 3.4 Mg/yr (3.7 tons/yr). The control
level associated with Option III would reduce emissions over
Options I and II by 99 and 83 percent, or 3.6 Mg/yr (3.9 tons/yr)
and 0.21 Mg/yr (0.23 ton/yr), respectively.
6.3 ENERGY IMPACTS
This section presents the energy impacts associated with
each control option. Electrical energy is needed to provide fan
horsepower for operating exhaust ventilation systems and
overcoming the pressure drop across control devices and to
operate recirculation pumps on the packed-bed scrubbers and mesh-
pad mist eliminators. The fan horsepower requirements for
exhaust ventilation only are presented in Table 6-8. The
electrical requirements shown in the table are based on the
6-6
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number of fans, the individual fan sizes for each model plant,
and the number of hours the plant operates each year. For
example, the estimated energy requirements for the basic capture
system for the small hard chromium model plant, as shown in
Table 6-8, is calculated as follows:
(1 fan)(10 hp/fan)(0.746 kW/hp)(2,000 hr/yr) = 14,900 kWh/yr.
The basic capture system is applicable for use with scrubbers and
chevron-blade mist eliminators, which can handle airflow rates up
to 1,680 m3/min (60,000 ft3/min). The modified capture system
shown in the table is intended to accommodate mesh-pad mist
eliminators. These control devices are designed to handle a
maximum airflow rate of 340 m3/min (12,000 ft3/min), which is
considerably lower than the maximum design airflow rates for
scrubbers and chevron-blade mist eliminators. The energy
requirements for this system are calculated in the same way as
for the basic capture system.
The increases in annual energy requirements for the control
devices, compared to the ventilation systems alone, are presented
in Table 6-9. These increases in electrical requirements are
based on the numbers and sizes of fans and pumps for each model
plant, and the number of hours the plant operates each year. Fan
and pump horsepower requirements vary according to the control
device being used. For example, the increase in energy
requirements for the small model plant when a mesh-pad mist
eliminator is used is determined as follows:
Mesh-pad mist eliminators require a modified capture system,
and the fan horsepower requirement for the small hard
chromium plating model plant for that system (as shown in
Table 6-8) is 7.5 hp. Table 6-9 shows that the mesh-pad
mist eliminator used in this model plant requires an
additional 7.5 hp to operate the fans and an additional
0.75 hp to operate the pumps. Therefore, the increase in
electrical use over that required for the modified capture
system alone is:
6-7
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(7.5 hp + 0.75 hp)(0.746 kW/hp)(2,000 hr/yr) = 11,200 kWh/yr.
Fan and pump horsepower requirements were provided by Vendors A
and I.1'2
6.3.1 Hard Chromium Electroplating
Table 6-10 presents the nationwide energy impacts associated
with each control option for hard chromium plating operations.
(Note that in this table, Option III is divided into two parts--
Option Ilia is based on the use of packed-bed scrubbers, and
Option Illb is based on the use of mesh-pad mist eliminators.)
The nationwide energy requirement for Option I (no action) is
calculated below.
There are 310 medium hard chromium plating operations, of
which 30 percent (93 operations) are uncontrolled, 30 percent are
controlled by chevron-blade mist eliminators with single sets of
blades, and 40 percent (124 operations) are controlled by
packed-bed scrubbers. The energy requirements for the
93 uncontrolled operations are attributable only to the basic
capture system. As shown in Table 6-8, the energy requirement
for a basic capture system for a medium hard chromium plating
operation is 104,400 kWh/yr. Therefore, the nationwide energy
requirement for uncontrolled medium-size hard chromium plating
operations is:
(93 operations)(104,400 kWh/yr) =
9.70 x 106 kWh/yr, or 9,700 MWh/yr.
The energy requirements for the 93 operations controlled by
chevron-blade mist eliminators with single sets of blades include
energy for the basic capture system plus additional fan
horsepower to operate the mist eliminator. As shown in
Table 6-9, the increase in electrical use over the basic capture
system alone is 26,100 kWh/yr for a medium hard chromium plating
model plant. The nationwide energy requirement for these
operations is, therefore:
6-8
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(93 operations)(26,100 kWh/yr + 104,400 kWh/hr) =
1.21 x 107 kWh/yr or 12,100 MWh/yr.
As shown in Table 6-9, the energy requirements for a medium hard
chromium plating operation controlled by a packed-bed scrubber
increase by 60,100 kWh/yr over the requirements for the basic
capture system. The nationwide energy requirement for these
operations is:
(124 operations)(60,100 kWh/yr + 104,400 kWh/yr) =
2.04 x 107 kWh/yr or 20,400 MWh/yr.
The estimated nationwide energy requirement for medium hard
chromium model plants is, therefore:
9,700 MWh/yr + 12,100 MWh/yr + 20,400 MWh/yr = 42,200 MWh/yr.
Similar calculations were performed for the small and large model
plants. The total nationwide energy requirement for hard
chromium plating operations under Option I is the sum of the
totals for each plant size, or 132,600 MWh/yr.
The energy requirement under Option II is based on the use
of a chevron-blade mist eliminator with a double set of blades.
The nationwide energy requirement for Option II is greater than
that for Option I because additional fan horsepower (compared to
the basic capture system) is required to operate chevron-blade
mist eliminators with a double set of blades in all sizes of
model plants. The number of operations controlled by packed-bed
scrubbers remains constant under both options and, therefore,
there is no additional energy requirement for those operations.
The total nationwide energy requirement for Option II is equal to
the nationwide energy requirement for Option I plus
24,200 MWh/yr, or 156,800 MWh/yr.
The energy requirement under Option Ilia (based on the use
of packed-bed scrubbers) is greater than that for Options I and
II because the number of operations controlled by scrubbers
6-9
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increases above the levels in Options I and II, and scrubbers
require additional energy to operate the fans and recirculation
pumps compared to mist eliminators. The increase in the energy-
requirements for the additional fan and recirculation pump
horsepower for scrubbers was calculated based on the increase in
the number of operations controlled by scrubbers (60 percent) and
the incremental fan and recirculation pump horsepower
requirements for each plant size. The incremental increase in
energy requirements for the medium hard chromium plating model
plant is calculated as follows:
The additional energy requirement for the 30 percent of
operations uncontrolled under Option I that would be
controlled by packed-bed scrubbers under Option Ilia is:
(0.30) (310 operations) (60,100 kWh/yr) =
5.59 x 106 kWh/yr or 5,600 MWh/yr.
As shown in Table 6-9, operations using chevron-blade mist
eliminators already have an increase in energy requirements
(26,100 kWh/yr per plant) over the basic capture system.
This must be subtracted from the energy increase due to the
use of packed-bed scrubbers (60,100 kWh/yr per plant). The
additional energy requirement for the 30 percent of
operations controlled by chevron-blade mist eliminators with
a single set of blades under Option I that would be
controlled by packed-bed scrubbers under Option Ilia is:
(0.30) (310 operations) (60,100 kWh/yr - 26,100 kWh/yr) =
3.16 x 106 kWh/yr or 3,200 MWh/yr.
No additional energy is required for the 40 percent of
operations controlled by packed-bed scrubbers under
Option I. The total increase in energy requirement for the
medium model plant under Option Ilia is 5,600 MWh/yr plus
3,200 MWh/yr, or 8,800 MWh/yr. Similar calculations were
performed for the small and large model plants. The total
6-10
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increase in energy requirements under Option Ilia is equal
to the sum of the nationwide totals for each model plant
size, which is 29,500 MWh/yr. The total nationwide energy
requirement for Option Ilia is then equal to the nationwide
energy requirement for Option I plus 29,500 MWh/yr, which is
162,200 MWh/yr.
The energy requirement for Option Illb is based on the use
of mesh-pad mist eliminators. As with Option Ilia, there is an
increase in nationwide energy requirements over Option I,
attributable to an increase in the fan horsepower and
recirculation pump horsepower requirements for the 30 percent of
operations uncontrolled under Option I. However, for the
30 percent of medium and large plants using chevron-blade mist
eliminators with a single set of blades under baseline conditions
(Option I), the use of mesh-pad mist eliminators results in an
incremental decrease in the energy requirement. The total fan
plus total pump horsepower requirements required for the medium
and large plants using mesh-pad mist eliminators are the same as
the total fan horsepower requirements for the same plants using
chevron-blade mist eliminators with a single set of blades (50 hp
and 100 hp, respectively). However, the recirculation pumps
required for mesh-pad mist eliminators are operated only
5 minutes in each 8-hour time period. Therefore, the total
increase in electrical use over the basic capture system is less
for mesh-pad mist eliminators than it is for chevron-blade mist
eliminators for these operations. Energy requirements for the
40 percent of operations controlled by packed-bed scrubbers under
Option I do not increase. The total nationwide energy
requirement for Option Illb is equal to the nationwide energy
requirement for Option I plus 8,100 MWh/yr, or 140,800 MWh/yr.
6.3.2 Decorative Chromium Electroplating
Table 6-11 presents the nationwide energy requirements
associated with each control option for decorative chromium
electroplating. The nationwide energy requirement for Option I
(baseline) is based on the basic capture systems for 55 percent
of the plants because these plants are either uncontrolled
6-11
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(15 percent) or use fume suppressants only (40 percent). The
45 percent of operations controlled by packed-bed scrubbers alone
or fume suppressants used in conjunction with packed-bed
scrubbers have additional fan horsepower and pump electrical
requirements over those of the basic capture system. The
estimated energy requirement for decorative chromium plating
operations under Option I is 106,100 MWh/yr, which is calculated
from the values given in Tables 6-8 and 6-9 as described in
Section 6.3.1.
The energy requirement under Option Ila is based on the use
of packed-bed scrubbers. The nationwide energy requirement for
Option Ila increases over that for Option I because the number of
operations controlled by scrubbers increases from 45 percent in
Option I to 60 percent in Option Ila. This is due to the number
of operations uncontrolled under Option I becoming controlled by
packed-bed scrubbers under Option Ila. The increase in the fan
and pump energy requirements is calculated as follows:
(336 small plants)(9,700 kWh/yr) + (63 medium plants)
(38,800 kWh/yr) + (21 large plants) (134,300 kWh/yr) =
8.52 x 106 kWh/yr or 8,500 MWh/yr.
Therefore, the total nationwide energy requirement for Option Ila
is equal to the nationwide energy requirement for Option I plus
8,500 MWh/yr, which is 114,600 MWh/yr.
The energy requirement under Option lib is based on the use
of mesh-pad mist eliminators. As with Option Ila, the increase
in fan and pump horsepower energy requirements results in
incremental energy increases only for the 15 percent of
operations that are uncontrolled under Option I and have only
basic capture systems. The total increase in fan energy
requirements (see Table 6-9) is determined for each model plant
size using calculations similar to those presented for
Option Ila. Additional energy required for recirculation pumps
is determined in a similar manner but calculations are adjusted
to reflect the use of these pumps for only 5 minutes in each
6-12
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8-hour time period. The total incremental energy increase for
Option lib is 8,200 MWh/yr. Therefore, the total nationwide
energy requirement for Option lib is equal to the nationwide
energy requirement for Option I plus 8,200 MWh/yr, which is
114,300 MWh/yr.
The energy requirement under Option III is based on the use
of fume suppressants. The nationwide energy requirement for
Option III is the same as the nationwide energy requirement for
Option I for 97.5 percent of the operations because no
modifications to the basic capture systems at these operations
are needed for the purpose of this control technology. For the
5 percent of the operations using packed-bed scrubbers under
Option I, it is assumed that half will retain their packed-bed
scrubbers in addition to using fume suppressants. For the
remaining 2.5 percent, an incremental energy decrease is realized
when fume suppressants alone are used. This is attributable to
the elimination of scrubbers in these operations and the
associated fan and pump energy requirements. The total
incremental energy decrease for Option III is 1,400 MWh/yr.
Therefore, the total nationwide energy requirement for Option III
is equal to the nationwide energy requirement for Option I less
1,400 MWh/yr, which is 104,700 MWh/yr.
The energy requirement under Option IV is based on the use
of the trivalent chromium process as a substitute for the
hexavalent chromium process. The nationwide energy requirement
for Option IV is zero because no ventilation systems are required
for trivalent chromium plating tanks. This represents a
reduction of 106,100 MWh/yr.
6.3.3 Chromic Acid Anodizing
Table 6-12 presents nationwide estimates of the annual
energy use associated with the control options. The nationwide
energy requirement for Option I (baseline) is based on the basic
capture systems for all operations and the additional fan
horsepower and pump electrical requirement for all sizes of
operations that operate scrubbers. The operation of chevron-
blade mist eliminators at these plants does not increase the fan
6-13
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horsepower requirement over that of the basic capture system.
Based on the fan and pump horsepower requirements, the number of
operations nationwide, and the percentage of all operations
controlled by scrubbers, the estimated energy requirement for
chromic acid anodizing operations under Option I is
47,800 MWh/yr.
The energy requirement under Option Ila is based on the use
of packed-bed scrubbers. The nationwide energy requirement for
Option Ila increases over that for Option I because the number of
operations controlled by scrubbers increases above the number for
Option I, and these operations require additional fan horsepower
and energy to operate the recirculation pumps. The total
incremental energy increase for Option Ila over Option I is
8,000 MWh/yr. The total nationwide energy requirement for
Option Ila is 55,800 MWh/yr.
The energy requirement for Option lib is based on the use of
mesh-pad mist eliminators. For 50 percent of the operations
there is an increase in fan energy requirements, and additioncil
energy is required to operate the recirculation pumps for
5 minutes in each 8-hour time period for the mesh-pad mist
eliminators. The total incremental energy increase for
Option lib over Option I is 5,600 MWh/yr. The total nationwide
energy requirement for Option lib is 53,400 MWh/yr.
The energy requirement under Option III is based on the use
of fume suppressants. There is no increase in the energy
requirement for Option III over that for Option I because no
modifications to the basic capture systems of any operations are
needed for this control technology. For 20 percent of the
operations there is an incremental decrease in electrical use
attributable to the incremental fan and pump horsepower
requirements associated with the packed-bed scrubbers used in
those operations. The total incremental energy decrease for
Option III is 3,200 MWh/yr. The total nationwide energy
requirement for Option III is 44,600 MWh/yr.
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6.4 WATER POLLUTION IMPACTS
Wet scrubbers and mist eliminators generate wastewater that
requires reuse, treatment, or disposal. Some hard and most
decorative plating operations install systems to treat wastes
from plating baths. Some of these operations also drain the
control device effluent to the treatment system. The amount of
control device effluent relative to the total amount of
wastewater associated with plating operations is low (less than
10 percent).
Hard chromium plating and chromic acid anodizing operations
that use scrubbers typically avoid wastewater treatment costs and
minimize water consumption by continuously recirculating scrubber
liquor. The scrubber liquor is recirculated for a period ranging
from several hours to several days and then is drained to the
plating bath to make up for plating solution evaporation losses.
The scrubber is recharged with clean water after being drained.
This practice also permits the recovery of chromic acid.
Operations using chevron-blade mist eliminators also recover
chromic acid by draining the washdown water to the plating tank
to make up for plating solution evaporation losses.
Decorative chromium plating operations that use scrubbers
typically do not use scrubber liquor to make up for plating
solution evaporation losses because fume suppressants are used to
minimize evaporation losses. Many decorative plating operations
avoid wastewater treatment costs and minimize water consumption
by recirculating the water from the rinse tanks following the
chromium plating tank through the scrubber.
Under Option IV for decorative chromium plating, operations
would be faced with the problem of disposal of the hexavalent
chromium plating solution as a part of the conversion to the
trivalent process. Because this is considered to be a one-time
occurrence, it is treated as a component of the capital cost of
conversion rather than a continuing impact of the control option.
More details on the impact of disposing of the plating solution
are presented in Chapter 7. The long-term impacts of Option IV
6-15
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on water pollution would be beneficial because the use of the
more toxic hexavalent solution is eliminated.
6.5 SOLID WASTE IMPACTS
One potential source of solid waste from hard and decorative
plating and chromic acid anodizing operations is the sludge
produced by wastewater treatment systems. As noted in
Section 6.4, wastewater from plating baths and control devices is
typically recirculated. This minimizes wastewater treatment
system throughput, and, therefore, the quantities of sludge
generated are not significant.
Implementation of the contrql options based on the use of
packed-bed scrubbers or mesh-pad mist eliminators will have some
solid waste impacts. Vendors estimate that bed packing materials
used in scrubbers may need to be replaced every 10 years and that
mesh pads used in mesh-pad mist eliminators should be replaced
every 4 years. Hexavalent chromium-contaminated materials such
as these are accepted for disposal in hazardous waste landfills.
The costs for disposal of these materials are addressed in
Chapter 7. The total volumes of solid wastes attributable to the
disposal of scrubber packing material and mesh pads for the model
plants are presented in Tables 6-13 through 6-15. The quantities
of spent scrubber packing material and mesh pads generated
annually under Option I (baseline conditions) would be 44 m3
(1,600 ft3) for hard chromium plating operations, 67 m3
(2,400 ft3) for decorative chromium plating operations, and 8 m3
(280 ft3) for chromic acid anodizing operations. Control options
based on the use of single packed-bed scrubbers would increase
this to 110 m3 (3,900 ft3) for hard chromium plating operations,
89 m3 (3,100 ft3) for decorative plating operations, and 29 m3
(1,000 ft3) for chromic acid anodizing operations. Control
options based on the use of mesh-pad mist eliminators would
increase the quantities from those in Option I to 100 m3
(3,500 ft3) for hard chromium plating operations, 82 m3
(2,900 ft3) for decorative plating operations, and 26 m3
(920 ft ) for chromic acid anodizing. These increases are not
considered to represent significant solid waste impacts.
6-16
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Another source of solid waste is the retrofitting or
replacement of control devices at existing operations. Disposal
of replaced systems represents a one-time occurrence for each
operation, and the extent of the impact depends on the type of
modification involved. Costs pertinent to disposal of control
device systems are discussed in Chapter 7.
The conversion to a trivalent chromium plating process
involves the disposal of the hexavalent solution as a hazardous
waste. This is a one-time impact and is covered in Chapter 7 as
a cost item. Therefore, there are no significant solid waste
impacts associated with this or other options for the three
source categories.
As a result of legislation proposed at the time of this
writing, the solid waste impacts described above may increase
significantly.
6.6 OTHER ENVIRONMENTAL IMPACTS
No other beneficial or adverse environmental impacts are
expected to arise from the implementation of the standards,
regardless of the control option selected as the basis of the
standards.
6.7 OTHER ENVIRONMENTAL CONCERNS
6.7.1 Irreversible and Irretrievable Commitment of Resources
As discussed in Section 6.3, the control options will result
in an increase in the irreversible and irretrievable commitment
of energy resources. However, this increased energy demand for
pollution control is insignificant compared to the existing
energy demand for the electroplating and anodizing processes and
capture systems.
6.7.2 Environmental Impact of Delayed Regulatory Action
The only detrimental environmental impact associated with a
delay in proposing and promulgating the standard would be the
continued generation of hexavalent chromium emissions at the
rates described earlier in this chapter. The Administrator has
determined that this may reasonably be anticipated to endanger
public health or welfare.
6-17
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Delaying the standard would result in possible solid waste
and energy impact reductions. However, the related reductions
would be minimal compared with the air quality benefits
attributable to promulgation of the standard.
6-18
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TABLE 6-1.
CONTROL TECHNIQUES UPON WHICH THE CONTROL OPTION
ENVIRONMENTAL IMPACTS ARE BASED
Type of operation/
Control option
Control technique
Hard chromium plating
Option I (no action)
Option n
Option in
Decorative chromium plating
Option I (no action)
Option II
Option ffl
Option IV
Chromic acid anodizing
Option I (no action)
Option n
Option ID
Existing (baseline) level of control
• 30 percent of operations uncontrolled
• 30 percent of operations controlled by chevron-blade mist
eliminators that reduce uncontrolled emissions by 90 percent
• 40 percent of operations controlled by packed-bed scrubbers that
reduce uncontrolled emissions by 97 percent
Chevron-blade mist eliminators that reduce uncontrolled emissions by
95 percent
Packed-bed scrubbers or mesh-pad mist eliminators that reduce
uncontrolled emissions by 99 percent
Existing (baseline) level of control
• 15 percent of operations uncontrolled
• 40 percent of operations controlled by chemical fume suppressants
that reduce uncontrolled emissions by 97 percent
• 40 percent of operations controlled by a combination of chemical
fume suppressants and packed-bed scrubbers that reduces
uncontrolled emissions by 97 percent
• 5 percent of operations controlled by packed-bed scrubbers that
reduce uncontrolled emissions by 95 percent
Packed-bed scrubbers or mesh-pad mist eliminators that reduce
uncontrolled emissions by 97 percent
Chemical fume suppressants applied in accordance with vendor
recommendations. Uncontrolled emissions reduced by 99.5 percent
Trivalent chromium plating processes that reduce hexavalent chromium
emissions by 100 percent (technology-forcing)
Existing (baseline) level of control
• 40 percent of operations uncontrolled
• 30 percent of operations controlled by chemical fume suppressants
that reduce uncontrolled emissions by 97 percent
• 10 percent of operations controlled by chevron-blade mist
eliminators that reduce uncontrolled emissions by 90 percent.
• 20 percent of operations controlled by packed-bed scrubbers that
reduce uncontrolled emissions by 95 percent
Packed-bed scrubbers or mesh-pad mist eliminators that reduce
uncontrolled emissions by 97 percent
Chemical fume suppressants applied in accordance with vendor
recommendations. Uncontrolled emissions reduced by 99.5 percent
6-19
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TABLE 6-2. NATIONWIDE HEXAVALENT CHROMIUM EMISSION ESTIMATES
ASSOCIATED WITH CONTROL OPTIONS FOR HARD CHROMIUM PLATING
OPERATIONS
Model plant production rate, Ah/yr (x 10")
Uncontrolled emission factor, mg/Ah (gr/Ah)
Model plant uncontrolled emission rate, kg/yr
(Ib/yr)
Model plant uncontrolled emission rate, Mg/yr
(tons/yr)
No. of operations nationwide4
V f' 'A • '
Option I (no-action)
30 percent UNC0
30 percent CBME at 90 percentd
40 percent PBS at 97 percent6
TOTALa
Option n (95 percent) f
Emissions for:§
30 percent CBME at 95 percent
30 percent CBME at 95 percent
40 percent PBS at 97 percent
TOTAL3
Option III (99 percent)11
Emission for:2
30 percent PBS or MPME at 99 percent
30 percent PBS or MPME at 99 percent
40 percent PBS or MPME at 99 percent
TOTALa
Small
5
10.0(0.15)
50(110)
0.05 (0.055)
1,080
estimates, Mg/yr (t
16 (18)
1.6(1.8)
0.65 (0.71)
18 (20)
0.81 (0.89)
0.81 (0.89)
0.65 (0.71)
2.3 (2.5)
0.16(0.18)
0.16(0.18)
0.22 (0.24)
0.5 (0.6)
Plant size
Medium
42
10.0(0.15)
420 (926)
0.42 (0.46)
310
39 (43)
3.9 (4.3)
1.6(1.7)
45 (49)
2.0 (2.2)
2.0 (2.2)
1.6(1.7)
5.5 (6.0)
0.39 (0.43)
0.39 (0.43)
0.52 (0.57)
1.3 (1.4)
Large
160
10.0(0.15)
1,600(3,530)
1.60(1.76)
150
72 (79)
7.2 (7.9)
2.9 (3.2)
82(90)
3.6 (4.0)
3.6 (4.0)
2.9(3.2)
10(11)
0.72 (0.79)
0.72 (0.79)
0.96 (1.1)
2.4 (2.6)
Total
1,540
145 (160)
18 (20)
4.2 (4.7)
aNote: Numbers may not add exactly due to independent rounding.
"Option I is based on the existing level of control.
CUNC = Uncontrolled.
^CBME = Chevron-blade mist eliminator that reduces uncontrolled emissions by 90 percent.
ePBS = Packed-bed scrubber that reduces uncontrolled emissions by 97 percent.
^Based on the use of chevron-blade mist eliminators that reduce uncontrolled emissions by 95 percent.
^Percentage of plants nationwide for which emission reduction will be achieved by use of the control technique
upon which the control option is based.
nBased on the use of packed-bed scrubbers or mesh-pad mist eliminators (MPME) that reduce uncontrolled
emissions by 99 percent.
6-20
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TABLE 6-4. NATIONWIDE HEXAVALENT CHROMIUM EMISSION
ESTIMATES ASSOCIATED WITH CONTROL OPTIONS FOR DECORATIVE
CHROMIUM PLATING OPERATIONS
Model plant production rate, Ah/yr (x 10")
Uncontrolled emission factor, mg/Ah (gr/Ah)
Model plant uncontrolled emission rate, kg/yr (lb/yr)
Model plant uncontrolled emission rate, Mg/yr
(tons/yr)
No. of plants nationwide
Nfitinmi'iHr' cirri ***"
Option I (no-action)
15 percent UNCC
40 percent FS at 97 percent*1
40 percent FS and PBS at 97 percent6
5 percent PBS at 95 percent^
TOTAL*
Option II (97 percent)^
Emissions for:
15 percent PBS or MPME at 97 percent
40 percent FS at 97 percent
40 percent FS and PBS at 97 percent
5 percent PBS at 97 percent
TOTALa
Option III (99.5 percent)1
Emissions for.
15 percent FS at 99.5 percent
42.5 percent FS at 99.5 percent
42.5 percent FS and PBS at 99.5 percent
TOTALa
Option IV (100 percent))
Emissions for:
15 percent TVC at 100 percent
40 percent TVC at 100 percent
40 percent TVC at 100 percent
5 percent TVC at 100 percent
TOTAL*
Small
3
2.0 (0.031)
6.0 (13)
0.006 (0.0065)
2,240
ion estimates, Mg/yr
2.0 (2.2)
0.16 (0.18)
0.16 (0.18)
0.03 (0.04)
2.4 (2.6)
0.06 (0.07)
0.16(0.18)
0.16 (0.18)
0.02 (0.02)
0.40 (0.44)
0.01 (0.01)
0.03 (0.03)
0.03 (0.03)
0.07 (0.07)
0
0
0
0
0
Plant size
Medium
12
2.0(0.031)
24 (53)
0.024 (0.027)
420
1.5 (1.7)
0.12 (0.13)
0.12 (0.13)
0.03 (0.03)
1.8 (2.0)
0.05 (0.05)
0.12(0.13)
0.12 (0.13)
0.02 (0.02)
0.30 (0.33)
0.01 (0.01)
0.02 (0.02)
0.02 (0.02)
0.05 (0.06)
0
0
0
0
0
Large
120
2.0 (0.031)
240 (530)
0.24 (0.27)
140
5.0 (5.5)
0.40 (0.44)
0.40 (0.44)
0.08 (0.09)
5.9 (6.5)
0.15 (0.17)
0.40 (0.44)
0.40 (0.44)
0.05 (0.06)
1.0(1.1)
0.03 (0.03)
0.07 (0.08)
0.07 (0.08)
0.17 (0.19)
0
0
0
0
0
Total
2,800
10 (11)
1.7 (1.9)
0.29 (0.32)
0
aNote: Numbers may not add exactly due to independent rounding.
"Option I is based on the existing level of control.
CUNC = Uncontrolled.
"FS = Fume suppressant that reduces uncontrolled emissions by 97 percent.
eFS and PBS = Combination of fume suppressant and packed-bed scrubber that reduces emissions by 97 percent.
*PBS = Packed-bed scrubber that reduces uncontrolled emissions by 95 percent.
^Based on the use of packed-bed scrubbers or mesh-pad mist eliminators (MPME) that would reduce uncontrolled emissions
by 97 percent.
"Percentage of plants nationwide for which emission reduction will be achieved by use of the control technique upon which
the control option is based.
'Based on the use of fume suppressants consistent with vendor recommendations. Uncontrolled emissions would be reduced
by 99.5 percent.
JBased on the substitution of a trivalent chromium (TVC) plating bath for the conventional hexavalent chromium plating
bath. Uncontrolled hexavalent chromium emissions would be reduced by 100 percent.
6-22
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6-24
-------
TABLE 6-6. NATIONWIDE HEXAVALENT CHROMIUM EMISSION ESTIMATES
ASSOCIATED WITH CONTROL OPTIONS FOR CHROMIC ACID
ANODIZING OPERATIONS
Plant size
Small
Large
Total
Uncontrolled emission factor, kg/hr/m2
Model plant uncontrolled emission rate, kg/yr
Model plant uncontrolled emission rate, Mg/yr (tons/yr)
No. of plants nationwide
Nationwide emission estimates, Mg/yr (tons/yr)a-
Option I (no-actionr
40 percent UNC°
6(1.2)
3.3 (7.2)
0.0033 (0.0036)
515
6 (1.2)
40(88)
0.04 (0.044)
165
680
10 percent CBME at 90 percent0
20 percent PBS at 95 percent0
30 percent FS at 97 percent'
TOTAL*
Option n (97 percent)^
Emissions for:h
40 percent PBS or MPME at 97 percent
10 percent PBS or MPME at 97 percent
20 percent PBS or MPME at 97 percent
30 percent FS at 97 percent
TOTAL3
Option ffl (99.5 percent)'
Emissions for:^
40 percent FS at 99.5 percent
10 percent FS at 99.5 percent
20 percent FS at 99.5 percent
30 percent FS at 99.5 percent
TOTAL8
0.68 (0.74)
0.02 (0.02)
0.02 (0.02)
0.02 (0.02)
0.74 (0.80)
0.02 (0.02)
0.01 (0.01)
0.01 (0.01)
0.02 (0.02)
0.05 (0.06)
0.003 (0.004)
0.001 (0.001)
0.002 (0.002)
0.003 (0.003)
0.01 (0.01)
2.7 (2.9)
0.06 (0.07)
0.07 (0.07)
0.06 (0.07)
2.8(3.1)
0.08 (0.09)
0.02 (0.02)
0.04 (0.04)
0.06 (0.07)
0.20 (0.22)
0.013 (0.015)
0.003 (0.004)
0.007 (0.008)
0.010(0.011)
0.03 (0.04)
3.6 (3.9)
0.25 (0.27)
0.04 (0.05)
aNote: Numbers may not add exactly due to independent rounding.
Option I is based on the existing level of control.
CUNC = Uncontrolled.
CBME = Chevron-blade mist eliminator that reduces uncontrolled emissions by 90 percent.
ePBS = Packed-bed scrubber that reduces uncontrolled emissions by 95 percent.
'FS = Fume suppressant that reduces uncontrolled emissions by 97 percent.
§Based on the use of packed-bed scrubbers or mesh-pad mist eliminators that would reduce uncontrolled
emissions by 97 percent.
"Percentage of plants nationwide for which emission reduction will be achieved by use of the control technique
upon which the control options are based.
'Based on the use of fume suppressants consistent with vendor recommendations. Uncontrolled emissions would
be reduced by 99.5 percent.
6-25
-------
TABLE 6-7. NATIONWIDE EMISSION REDUCTIONS ATTRIBUTABLE TO
EACH CONTROL OPTION FOR CHROMIC ACID ANODIZING OPERATIONS
Control options
Hexavalent chromium emission reductions, Mg/yr
(tons/yr)
Small
Large
Total
Option II vs. Option I
Emissions under Option I
Emissions under Option n
Emission reduction for Option II
Percent reduction over Option I
Option HI vs. Option I
Emissions under Option I
Emissions under Option in
Emission reduction for Option HI
Percent reduction over Option I
Option III vs. Option n
Emissions under Option n
Emissions under Option HI
Emission reduction for Option HI
Percent reduction over Option H
0.74 (0.80)
0.05 (0.06)
0.69 (0.76)
93
0.74 (0.80)
0.01 (0.01)
0.73 (0.80)
99
0.05 (0.06)
0.01 (0.01)
0.04 (0.04)
83
2.8(3.1)
0.20 (0.22)
2.6 (2.9)
93
2.8(3.1)
0.03 (0.04)
2.8(3.1)
99
0.20 (0.22)
0.03 (0.04)
0.17 (0.19)
83
3.6 (3.9)
0.25 (0.27)
3.4 (3.7)
93
3.6 (3.9)
0.04 (0.05)
3.6 (3.9)
99
0.25 (0.27)
0.04 (0.05)
0.21 (0.23)
83
6-26
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6-28
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6-29
-------
TABLE 6-10. NATIONWIDE ANNUAL ENERGY REQUIREMENTS ASSOCIATED
WITH CONTROL OPTIONS FOR HARD CHROMIUM PLATING OPERATIONS
Plant size
No. of operations nationwide:
30 percent UNC*
30 percent CBME(l) at 90 percent15
40 percent PBS at 97 percent0
TOTALd
Option I (no-action)6
30 percent UNC, MWh/yr
30 percent CBME(l) at 90 percent, MWh/yr
40 percent PBS at 97 percent, MWh/yr
Nationwide energy use, MWh/yr°
Option II (95 percent/ &
Increased electrical usage over Option I:
30 percent CBME(2) at 95 percent, MWh/yr
30 percent CBME<2) at 95 percent, MWh/yr
40 percent PBS at 97 percent, MWh/yr
TOTAL INCREASE, MWh/yr*1
Nationwide energy use, MWh/yr
(Option I total + total increase for Option II)
Option Ilia (99 percent/ h
Increased electrical usage over Option I:
30 percent PBS at 99 percent, MWh/yr J
30 percent PBS at 99 percent, MWh/yr
40 percent PBS at 99 percent, MWh/yr
TOTAL INCREASE, MWh/yrd
Nationwide energy use, MWh/yr
(Option I total + total increase for Option Ilia)
Option Illb (99 percent/'1
Increased electrical usage over Option I:
30 percent MPME at 99 percent, MWh/yr J
30 percent MPME at 99 percent, MWh/yr
40 percent PBS at 99 percent, MWh/yr
TOTAL INCREASE, MWh/yr*
Nationwide energy use, MWh/yrd
(Option I total + total increase for Option Illb)
Small
324
324
432
1,080
4,800
4,800
10.600
20,300
2,400
2,400
0
4,800
25,100
3,100
3,100
0
6,300
26,600
2,400
2,400
0
4,900
25,100
Medium
93
93
124
310
9,700
12,100
20.400
42,200
4,900
2,400
0
7,300
49,500
5,600
3,200
0
8,800
51,000
1,800
(600)
0
1,200
43,500
Large
45
45
60
150
16,100
20,100
33.800
70,100
8,100
4,000
0
12,100
82,200
9,300
5,200
0
14,500
84,600
3,000
(1,000)
0
2,000
72,100
Total
1,540
132,600
24,200
156,800
29,500
162,200
8,100
140,800
aUNC = Uncontrolled. Energy use based on capture system only.
kcBME(l) = Chevron-blade mist eliminators with single sets of blades that reduce uncontrolled emissions
by 90 percent.
CPBS = Packed-bed scrubbers that reduce uncontrolled emissions by 97 percent.
dNote: Numbers may not add exactly due to independent rounding.
eOption I is based on the existing level of control.
'Numbers were rounded to the nearest 100 MWh.
^Control Option II is based on the use of chevron-blade mist eliminators with a double set of blades (CBME(2)).
^Control Option Ilia is based on the use of single packed-bed scrubbers.
^Control Option Illb is based on the use of mesh-pad mist eliminators.
JMPME = Mesh-pad mist eliminators that reduce uncontrolled emissions by 99 percent.
6-30
-------
TABLE 6-11. NATIONWIDE ANNUAL ENERGY REQUIREMENTS
ASSOCIATED WITH CONTROL OPTIONS FOR DECORATIVE CHROMIUM
PLATING OPERATIONS
Plant size
No. of operations nationwide:
15 percent UNC*
40 percent FS at 97 percentb
40 percent FS + PBS at 97 percent0
5 percent PBS at 95 percent**
TOTAL6
Option I (no-actionr &
15 percent UNC, MWh/yr
40 percent FS at 97 percent, MWh/yr
40 percent FS + PBS at 97 percent, MWh/yr
5 percent PBS at 95 percent, MWh/yr
Nationwide energy use, MWh/yre
Option Ha (97 percenf)h i
Increased electrical usage over Option I:
15 percent PBS at 97 percent, MWh/yr
40 percent FS at 97 percent, MWh/yr
40 percent FS + PBS at 97 percent, MWh/yr
5 percent PBS at 97 percent, MWh/yr
TOTAL INCREASE, MWh/yre
Nationwide energy use, MWh/yre
(Option I total + total increase for Option Ha)
Option lib (97 percent^ '
Increased electrical usage over Option I:
15 percent MPME at 97 percent, MWh/yr J
40 percent FS at 97 percent, MWh/yr
40 percent FS + PBS at 97 percent, MWh/yr
5 percent PBS at 97 percent, MWh/yr
TOTAL INCREASE, MWh/yre
Nationwide energy use, MWh/yre
(Option I total + total increase for Option Ho)
Option HI (99.5 percent^ k
Increased electrical usage over Option I:
15 percent FS at 99.5 percent, MWh/yr
40 percent FS at 99.5 percent, MWh/yr
40 percent FS + PBS at 99.5 percent, MWh/yr
2.5 percent FS at 99.5 percent, MWh/yr
2.5 percent FS + PBS at 99.5 percent, MWh/yr
TOTAL INCREASE, MWh/yrc
Nationwide energy use, MWh/yre
(Option I total + total increase for Option HI)
Small
336
896
896
112
2,240
5,000
13,400
22,000
2.800
43,200
3,300
0
0
0
3,300
46,500
2,500
0
0
0
2,500
45,700
0
0
0
(500)
0
(500)
42,700
Medium
63
168
168
21
420
3,800
10,000
16,600
2.100
32,500
2,400
0
0
0
2,400
34,900
1,900
0
0
0
1,900
34,400
0
0
0
(400)
0
(400)
32,100
Large
21
56
56
_7
140
3,300
8,800
16,300
2.000
30,400
2,800
0
0
0
2,800
33,200
3,800
0
0
0
3,800
34,200
0
0
0
(500)
0
(500)
29,900
Total
2,800
106,100
8,500
114,600
8,200
114,300
(1,400)
104,700
6-31
-------
TABLE 6-11. (Continued)
Plant size
Option IV (100 peroenQg l
Increased electrical usage over Option I
15 percent TVC at 100 percent, MWh/yr111
40 percent TVC at 100 percent, MWh/yr
40 percent TVC at 100 percent, MWh/yr
5 percent TVC at 100 percent, MWh/yr
TOTAL INCREASE, MWh/yre
Nationwide energy use, MWh/yr
(Option I total + total increase for Option IV)
Small
(5,000)
(13,400)
(22,000)
(2.800)
(43,200)
0
Medium
(3,800)
(10,000)
(16,600)
(2.1001
(32,500)
0
Large
(3,300)
(8,800)
(16,300)
(2.0001
(30,400)
0
Total
(106,100)
0
aUNC = Uncontrolled. Energy use based on capture system only.
"FS = Fume suppressant that reduces uncontrolled emissions by 97 percent.
CFS + PBS = Fume suppressant and packed-bed scrubber that reduce uncontrolled emissions by 97 percent.
^PBS = Packed-bed scrubbers that reduce uncontrolled emissions by 95 percent.
eNote: Numbers may not add exactly due to independent rounding.
Option I is based on the existing level of control.
^Numbers are rounded to nearest 100 MWh.
"Based on the use of packed-bed scrubbers that reduce uncontrolled emissions by 97 percent.
'Based on the use of mesh-pad mist eliminators that reduce uncontrolled emissions by 97 percent.
JMPME = Mesh-pad mist eliminators that reduce uncontrolled emissions by 97 percent.
Based on use of fume suppressants that reduce uncontrolled emissions by 99.5 percent.
'Based on the substitution of a trivalent chromium plating bath for the conventional hexavalent chromium
plating bath that would reduce uncontrolled emissions by 100 percent. Energy use is zero because capture and
control systems are not required.
mTVC = Trivalent chromium process.
6-32
-------
TABLE 6-12. NATIONWIDE ANNUAL ENERGY REQUIREMENTS ASSOCIATED
WITH CONTROL OPTIONS FOR CHROMIC ACID ANODIZING OPERATIONS
Plant size
Small
Large
Total
No. of plants nationwide:
40 percent UNC*
10 percent CBME(l) at 90 percentb
20 percent PBS at 95 percentc
30 percent FS at 97 percent*1
TOTAL6
Option I (no-action)' 8
40 percent UNC, MWh/yr
10 percent CBME(l) at 90 percent, MWh/yr
20 percent PBS at 95 percent, MWh/yr
30 percent FS at 97 percent, MWh/yr
Nationwide energy use, MWh/yr6
Option Ha (97 percent^ h
Increased electrical usage over Option I:
40 percent PBS at 97 percent, MWh/yr
10 percent PBS at 97 percent, MWh/yr
20 percent PBS at 97 percent, MWh/yr
30 percent FS at 97 percent, MWh/yr
TOTAL INCREASE, MWh/yre
Nationwide energy use, MWh/yre
(Option I total + total increase for Option Ha)
Option lib (97 percent)^ '
Increased electrical usage over Option I:
40 percent MPME at 97 percent, MWh/yrJ
10 percent MPME at 97 percent, MWh/yr
20 percent PBS at 97 percent, MWh/yr
30 percent FS at 97 percent, MWh/yr
TOTAL INCREASE, MWh/yre
Nationwide energy use, MWh/yre
(Option I total + total increase for Option lib)
Option 111(99.5 percent^ k
Increased electrical use over Option I:
40 percent FS at 99.5 percent, MWh/yr
10 percent FS at 99.5 percent, MWh/yr
20 percent FS at 99.5 percent, MWh/yr
30 percent FS at 99.5 percent, MWh/yr
TOTAL INCREASE, MWh/yre
Nationwide energy use, MWh/yr6
(Option I total + total increase for Option HI)
206
51
103
155
515
3,100
800
2,500
2.300
8,700
2,000
500
0
_0
2,500
11,200
1,500
400
0
0
1,900
10,600
0
0
(1,000)
0
(1,000)
7,700
39,100
4,400
1,100
0
0
5,500
44,600
3,000
700
0
0
3,700
42,800
0
0
(2,200)
0
(2,200)
36,900
680
47,800
8,000
55,800
5,600
53,400
(3,200)
44,600
aUNC = Uncontrolled. Energy use based on capture system only.
"CBME(l) = Mist eliminator with single set of blades that reduces uncontrolled emissions by 90 percent.
CPBS = Energy use based on basic capture system and packed-bed scrubber that reduces uncontrolled emissions by
97 percent.
FS = Fume suppressant that reduces uncontrolled emissions by 97 percent.
eNote: Numbers may not add exactly due to independent rounding.
Option I is based on the existing level of control.
^Numbers were rounded to nearest 100 MWh.
Based on the use of packed-bed scrubbers that reduce uncontrolled emissions by 97 percent.
'Based on the use of mesh-pad mist eliminators that reduce uncontrolled emissions by 97 percent.
JMPME = Mesh-pad mist eliminators that reduce uncontrolled emissions by 97 percent.
Based on the use of fume suppressants consistent with vendor recommendations.
6-33
-------
TABLE 6-13. NATIONWIDE SOLID WASTE IMPACTS ASSOCIATED WITH
THE USE OF SINGLE PACKED-BED SCRUBBERS AND MESH-PAD MIST
ELIMINATORS FOR HARD CHROMIUM PLATING OPERATIONS
Plant size
Small* Mediumb
Large0
Total
Single packed-bed scrubbers
Total volume of packing material,
3 fft*\
Frequency of replacement, yr
Mesh-pad mist eliminators
Total volume of pads, m3 (ft3)
Frequency of replacement, yr
No. of operations nationwide
Option I (baselineV.
30 percent UNCT
30 percent CBME(1)S
40 percent PBS"
TOTAL
TOTAL ANNUALIZED1
Option 11
30 percent CBME(2) J
30 percent CBME(2)
40 percent PBS
TOTAL
TOTAL ANNUALIZED1
Option Ilia
30 percent PBS
30 percent PBS
40 percent PBS
TOTAL
TOTAL ANNUALIZED1
Option Illb
30 percent MPMEk
30 percent MPME
40 percent PBS
TOTAL FROM MPME
TOTAL FROM PBS
TOTAL ANNUALIZED1
0.82 (29)
10
0.26 (9.2)
4
1,080
2.1 (74)
10
0.72 (26)
4
310
Nationwide solid waste disposal estimates, m3 (fr) e
0
0
180 (6.400)
180 (6.400)
18 (6,400)
0
0
180 (6.400)
180 (6.400)
18 (640)
130 (4,600)
130 (4,600)
180 (6,400)
440 (15.500)
44 (1,600)
42 (1,500)
42 (1,500)
180 (6.400)
84 (3.000)
180 (6.400)
39 (1,400)
0
0
130 (4.600)
130 (4.600)
13 (460)
0
0
130 (4.600)
130 (4.600)
13 (460)
100 (3,500)
100 (3,500)
130 (4.600)
330(11.700)
33 (1,200)
33 (1,200)
33 (1,200)
130 (4.600)
66 (2.300)
130 (4.600)
30 (1,100)
4.2 (148)
10
1.4 (51)
4
150
0
0
130 (4.600)
130 (4.600)
13 (460)
0
0
130 (4.600)
130 (4.600)
13 (460)
90 (3,200)
90 (3,200)
130 (4.600)
310 (10.900)
31 (1,100)
32 (1,100)
32 (1,100)
130 (4.600)
64 (2.300)
130 (4.600)
29 (1,000)
1,540
440 (15,500)
44 (1,600)
440 (15,500)
44 (1,600)
1,100(38,800)
110 (3,900)
210 (7,400)
440 (15,500)
100 (3,500)
aThe small model plant has one control device using 0.82 m3 (29 fr) of disposable packing material for the scrubber or
0.26 m3 (9.2 ft3) of disposable material for the mesh-pad mist eliminator.
bThe medium model plant has one control device using 2.1 m3 (74 ft3) of disposable packing material for the scrubber or
four control devices (one using 0.13 m3 [4.7 ft3], one using 0.17 m3 [6.0 ft3], and two using 0.21 m3 [7.4 ft3] each of
disposable material) for the mesh-pad mist eliminator.
cThe large model plant has two control devices (each using 2.1m [74 ft3] of disposable packing material) for the scrubber
or eight control devices (two using 0.13 m [4.7 fr] each, two using 0.17 m [6.0 ft3] each, and four using 0.21 nr
[7.4 ft3] each of disposable material) for the mesh-pad mist eliminator.
dCalculations made using the assumption that waste material is compacted to 50 percent of its original volume.
eNumbers may not add exactly due to independent rounding.
fUNC = Uncontrolled.
8CBME(1) = Chevron-blade mist eliminator with a single set of blades.
hPBS = Single packed-bed scrubber.
kTosts for plants using mesh-pad mist eliminators are annualized by dividing by 4; costs for plants using packed-bed
scrubbers are annualized by dividing by 10.
JCBME(2) = Chevron-blade mist eliminator with a double set of blades.
= Mesh-pad mist eliminator.
6-34
-------
TABLE 6-14. NATIONWIDE SOLID WASTE IMPACTS ASSOCIATED WITH
THE USE OF SINGLE PACKED-BED SCRUBBERS AND MESH-PAD MIST
ELIMINATORS FOR DECORATIVE CHROMIUM PLATING OPERATIONS
Single packed-bed scrubbers
Total volume of packing material, m (ft )
Frequency of replacement, yr
Mesh-pad mist eliminators
Total volume of pads, m3 (ft3)
Frequency of replacement, yr
No. of operations nationwide
Option I (baseline)
15 percent UNC1
40 percent FSS
40 percent FS .+ PBSh
5 percent PBS'
TOTAL
TOTAL ANNUALJZEDJ
Option Da
15 percent PBS
40 percent FS
40 percent FS + PBS
5 percent PBS
TOTAL
TOTAL ANNUALIZED)
Option nb
15 percent MPMEk
40 percent FS
40 percent FS + PBS
5 percent PBS
TOTAL FOR PBS
TOTAL FOR MPME
TOTAL ANNUALJZEDJ
Option LQ
15 percent FS
40 percent FS
40 percent FS + PBS
2.5 percent FS
2.5 percent FS + PBS
TOTAL
TOTAL ANNUALIZED
Smalla
Plant
Medium15
0.82(29) 1.6(58)
10 10
0.26 (9.2) 0.52 (18.4)
4 4
2,240 420
waste disposal estimates, m (fr)
0 0
0 0
370(13,100) 130(4,600)
46 (1.600) 17 (600)
420 (14.800)
42 (1,500)
140 (4,900)
0
370(13,100)
46 (1,600)
560(19,800)
56 (2,000)
44 (1,600)
0
370(13,100)
46 (1.600)
44 (1,600)
420 (14.800)
53 (1,900)
0
0
370(13,100)
0
23 (810)
390(13.800)
39 (1,400)
150 (5.300)
15 (530)
50 (1,800)
0
130 (4,600)
17 (600)
200(7.100)
20 (710)
16 (570)
0
130 (4,600)
17 (600)
16 (570)
150 (5.300)
19(670)
0
0
130 (4,600)
0
8 (280)
140 (4.900)
14 (490)
size
Large0
3.1 (108)
10
1.0 (37)
4
140
e
0
0
87 (3,100)
11(390)
98 (3.500)
10 (350)
33 (1,200)
0
87 (3,100)
11 (390)
130 (4.600)
13 (460)
11 (390)
0
87 (3,100)
1 1 (390)
11 (390)
98 (3.500)
10 (350)
0
0
87 (3,100)
0
5 (180)
90 (3,200)
9 (320)
Total
2,800
670 (23,700)
67 (2,400)
890 (31,400)
89(3,100)
71 (2,500)
670 (23,700)
82 (2,900)
620 (21,900)
62 (2,200)
6-35
-------
TABLE 6-14. (Continued)
Plant size
Small3 Mediumb
Option IV
1.5 percent TVC1
40 percent TVC
40 percent TVC
5 percent TVC
TOTAL
TOTAL ANNUALIZED
0
0
0
0
0
0
0
0
0
0
Q
0
Large0
0
0
0
0
0
0
Total
0
0
aThe small model plant has one control device using 0.82 m^ (29 ft3) of disposable packing material for the
scrubber or 0.26 m3 (9.2 ft3) of disposable material for the mesh-pad mist eliminator.
"The medium model plant has two control devices, each using 0.82 m (29 ft3) of disposable packing material
for the scrubber or 0.26 m (9.2 fr) of disposable material for the mesh-pad mist eliminator.
cThe large model plant has three control devices (one using 0.68 m [24 fr] and two using 1.2 m [42 ft3]
each of disposable packing material) for the scrubber or five control devices (each using 0.21 m [7.4 ft3] of
disposable material) for the mesh-pad mist eliminator.
Calculations made using the assumption that waste material is compacted to 50 percent of its original volume.
eNumbers may not add exactly due to independent rounding.
fUNC = Uncontrolled.
SpS = Fume suppressant.
^FS + PBS = Fume suppressant used in conjunction with packed-bed scrubber.
'PBS = Single packed-bed scrubber,
JCosts for plants using mesh-pad mist eliminators are annualized by dividing by 4; costs for plants using packed-
bed scrubbers are annualized by dividing by 10.
^MPME = Mesh-pad mist eliminator.
'TVC = Trivalent chromium process.
6-36
-------
TABLE 6-15. NATIONWIDE SOLID WASTE IMPACTS ASSOCIATED WITH THE
USE OF SINGLE PACKED-BED SCRUBBERS AND MESH-PAD MIST ELIMINATORS
FOR CHROMIC ACID ANODIZING OPERATIONS
Single packed-bed scrubbers
Total volume of packing material, m3 (ft3)
Frequency of replacement, yr
Mesh-pad mist eliminators
Total volume of packing material, m3 (fr )
Frequency of replacement, yr
No. of operations nationwide
Option I (baseline)
40 percent UNCe
10 percent CBME(l)f
20 percent PBSS
30 percent FSh
TOTAL
TOTAL ANNUALIZED1
Option Ha
40 percent PBS
10 percent PBS
20 percent PBS
30 percent FS
TOTAL
TOTAL ANNUALIZED1
Option lib
40 percent MPME J
10 percent MPME
20 percent PBS
30 percent FS
TOTAL FROM MPME
TOTAL FROM PBS
TOTAL ANNUALIZED1
Option III
40 percent FS
10 percent FS
20 percent FS
30 percent FS
TOTAL
TOTAL ANNUALIZED
Small8
0.82 (29)
10
0.26 (9.2)
4
515
solid waste disposal estimates, m (ft3
0
0
42 (1,500)
0
42(1,500)
4 (140)
84 (3,000)
21 (740)
42 (1,500)
0
ISO (5.300)
15 (530)
27 (950)
7- (250)
42 (1,500)
0
34(1,200)
42 (1,500)
13 (460)
0
0
0
0
0
0
Plant size
Large"
2.4 (86)
10
0.84 (29.6)
4
165
)
0
0
40 (1,400)
0
40(1.400)
4 (140)
79 (2,800)
20(700)
40 (1,400)
0
140 (4,900)
14 (490)
28 (990)
7 (250)
40 (1,400)
0
35 (1,200)
40(1.400)
13 (460)
0
0
0
0
0
0
Total
680
80 (2,800)
8 (280)
290 (10,200)
29 (1,000)
69 (2,400)
82 (2,900)
26 (920)
0
0
"The small modej plant has one control device using 0.82 m3 (29 fr) of disposable packing material for the scrubber or
JX26 rrr (9.2 ft3) of disposable material for the mesh-pad mist eliminator.
''The large model plant has one control device using 2.4 m (86 fr) of disposable packing material for the scrubber or four
control devices (each using 0.21 m [7.4 fr] of disposable material) for the mesh-pad mist eliminator.
^Numbers may not add exactly due to independent rounding.
^Calculations made using the assumption that waste material is compacted to 50 percent of its original volume.
eUNC = Uncontrolled.
CBME(l) = Chevron-blade mist eliminator with a single set of blades.
SPBS = Single packed-bed scrubber.
FS = Fume suppressant.
^osts for plants using mesh-pad mist eliminators are annualized by dividing by 4; costs for plants using packed-bed
. scrubbers are annualized by dividing by 10.
JMPME = Mesh-pad mist eliminator.
6-37
-------
6 . 8 REFERENCES FOR CHAPTER 6
l. Cost Enclosure for Control Equipment Vendors: Vendor A.
Prepared for U. S. Environmental Protection Agency, Research
Triangle Park, North Carolina. December 31, 1986. p. 1-2.
2. Telecon. Barker, R., MRI, with Vendor I. February 21, 1989,
Cost information for mesh-pad mist eliminators.
6-38
-------
7. COST ANALYSIS OF CONTROL OPTIONS
7.1 INTRODUCTION
This chapter presents cost estimates for various control
options for controlling hexavalent chromium emissions from hard
and decorative chromium electroplating and chromic acid anodizing
operations. Control costs were based on the application of the
control options to the model plants presented in Chapter 5. The
bases for the cost estimates for each of the control options are
presented in Section 7.2. Capital and annualized costs estimated
for the model hard chromium plating plants are presented in
Section 7.3, for the model decorative chromium plating plants in
Section 7.4, and for the model chromic acid anodizing plants in
Section 7.5. Aggregate nationwide capital and annualized costs
and cost-effectiveness values are presented in Section 7.6.
Table 7-1 presents the control techniques upon which the cost
impacts are based for each control option. Other cost
considerations (e.g., water pollution, hazardous waste, and
occupational safety and health) are discussed in Section 7.7.
Unit costs (costs for individual control systems) that are used
in the model plants are presented in Appendix F. The economic
impacts associated with the control options are presented in
Chapter 8.
7.2 BASES FOR COSTS OF EMISSION CONTROL TECHNIQUES
7.2.1 New Operations
Cost information was obtained from several major vendors of
the control techniques typically used to reduce chromium
emissions from chromium plating and chromic acid anodizing
operations. Each vendor provided cost estimates based on the
model plant parameters presented in Chapter 5 to ensure a common
7-1
-------
basis for the cost estimates. Capital costs for ventilation
systems, including exhaust hoods and ductwork, are reported
separately from those for control devices. Plants typically have
to install ventilation systems to comply with occupational health
standards that limit potential employee exposure to chromium
emissions in the work place. Section 7.7.3 presents the capital
costs of ventilation hoods and ductwork for the model plants as
costs associated with the,OSHA Act. All cost data presented in
this chapter are in November 1988 dollars. Sources of data used
to calculate capital and annualized costs of the emissions
control techniques are listed in Table 7-2. Cost factors used to
calculate annualized costs are presented in Table 7-3.
7.2.1.1 Chevron-Blade Mist Eliminators and Packed-Bed
Scrubbers. Information on capital costs for each of five
different sizes of chevron-blade mist eliminators and packed-bed
scrubbers specified in the model plants were obtained from three
control device vendors (designated as Vendors A, B, and
£)_ 1,20,21 rpke vendors also provided operating parameters for
mist eliminators and scrubbers (e.g., fan and recirculation pump
motor horsepower [hp] requirements; water consumption rates;
labor and maintenance hours; and the life expectancy of control
devices) that were used to calculate annualized costs.
Vendor A provided the most complete and highest cost
estimates of the three vendors. Vendor B provided installed
capital cost estimates for mist eliminators and scrubbers that
ranged from $10,000 to $20,000 lower than those provided by
Vendor A. Annualized cost estimates calculated from the control
device operating parameters provided by Vendor B ranged from
$1,000 to $10,000 lower than the annualized cost estimates
calculated from the control device operating parameters provided
by Vendor A. Capital cost estimates provided by Vendor C were
incomplete because this vendor did not provide installation
costs. Therefore, cost estimates presented in this section are
based on the more complete cost data provided by Vendor A.
Capital and annualized cost estimates for chevron-blade mist
eliminators with single and double sets of blades and for single
7-2
-------
packed-bed scrubbers are presented and discussed in this chapter.
Costs for double packed-bed scrubbers are presented in
Appendix F.
7.2.1.1.1 Capital costs. The capital costs for
chevron-blade mist eliminators and packed-bed scrubbers include
the purchase cost of the control device and auxiliaries such as
exhaust fans, motors, inlet and outlet transitions, and stacks;
direct installation costs for electrical panels and wiring,
instrumentation and controls, and piping; indirect costs for
erection, engineering services, contractor fees, and
contingencies; and startup costs. Installation costs are based
on the assumption that the control device would be installed on
the roof of the plating shop, which is 6.1 m (20 ft) high and
would require no major structural modifications to support the
weight of the control device. Erection costs include the cost of
renting a crane to hoist the control device onto the roof of the
shop. The purchased equipment cost includes taxes and freight
costs as well, which are assumed to be 3 and 5 percent of the
base equipment cost, respectively.14 The startup cost is assumed
to be 1 percent of the purchased equipment cost.14
7.2.1.1.2 Annualized costs. The annualized costs include
direct operating costs such as utilities; operator, supervisor,
and maintenance labor and materials; indirect operating costs
such as overhead, property taxes, insurance and administration;
and capital recovery costs. The annualized costs of packed-bed
scrubbers also include the costs of scrubber packing replacement
and disposal.
A. Utility costs. Utility costs include the costs of
electricity and water required to operate chevron-blade mist
eliminators and packed-bed scrubbers. The annual electrical cost
attributable to pollution control results from the additional fan
horsepower needed to overcome the pressure drop added to the
ventilation system by the control device and (in the case of
packed-bed scrubbers) the horsepower needed to operate scrubber
recirculation pumps. Both the incremental fan and recirculation
7-3
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pump electrical costs were calculated using the following
equation:
0 746 kW
Electrical cost, $/yr = [( '—j- )(hp)(t)][C]
where:
kW = kilowatt;
hp = horsepower of pump motor or incremental horsepower of
fan motor;
t = operating time, hr/yr; and
C = electricity cost, $0.0461/kWh.9
Example; For a single packed-bed scrubber whose fan
requires an additional 5 hp to overcome the additional pressure
drop and that operates 6,000 hr/yr, the incremental annual
electrical cost to operate the fan is:
0.746 kW
hp
[5 hp]
6,000 hr
yr
In addition, the single packed-bed scrubber requires a 1-hp
pump to recirculate the scrubber water. The annual electrical
cost to operate the pump is:
Therefore, the total annual electrical cost for the scrubber
is $l,240/yr.
Water consumption costs are associated with the washdown of
chevron-blade mist eliminators and the operation of packed-bed
scrubbers. For the purposes of this analysis, it was assumed
that washdown occurs every 8 hours and the water for washdown of
mist eliminators is recycled to the process, as is typically the
case. Scrubber water also was assumed to be recirculated for
8 hours of operation, at which time the water in the
recirculation basin is drained to the process and the basin is
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replenished with clean water. Water costs were calculated using
the following equations:
(1) Chevron-blade mist eliminators
Water cost, $/yr = [(V) (N) (S)] [C]
where :
V = volume of water per washdown, L (gal) ;
N = number of washdowns per 8-hr shift;
S = number of 8 -hour shifts per year; and
C = water cost, $0.20/1,000 L ($0.77/1,000 gal).10
(2) Packed-bed scrubbers
Water cost, $/yr = [(V) (f)+(FR) (60 min/hr) (t)] [C]
where :
V = recirculation tank volume, L (gal) ;
f = frequency of washdowns, number per year;
FR = makeup water flow rate, L/min (gal/min) ;
t = operating time, hr/yr; and
C = water cost, $0.20/1,000 L ($0.77/1,000 gal).10
Example: If, for the single packed-bed scrubber used in the
examples above, the recirculation tank volume is 120 gal, the
makeup water flow rate is 1.5 gal/min, the scrubber is operated
6,000 hr/yr, and the scrubber water is drained to the process and
replaced with clean water after 8 hours of operation, or
750 times per year, the annual water cost for this unit is:
[(120 gal) (750) + (1.5 gal/min) (60 min/hr) (6, 000 hr/yr)]
The total annual cost of utilities for the scrubber is equal
to the sum of the annual electrical and water costs, which is
$l,730/yr.
B. Replacement costs. Scrubber packing replacement costs
were included in annualized scrubber costs because the life of
the packing material is less than the life of the control device.
Vendor A estimates that most operations will probably need to
replace the packing material every 10 years. The packing
7-5
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material costs approximately $620/m3 ($l7.50/ft3) of material.22
Annualized packing material replacement costs include the
replacement cost of the packing and the transportation and
disposal costs associated with the used packing. The replacement
costs of the packing material were calculated based on the
following equation:
Replacement cost, $/yr = [(V)(c)](CRF_)
where:
V = volume of packing required for each control device,
m3 (ft3);
c = cost of packing material, $620/m3 ($l7.50/ft3);2^ and
CRF = capital recovery factor of 0.1628, based on an
interest rate of 10 percent and a depreciable life of
10 years for the packing.
The transportation and disposal costs for the packing
material were calculated based on the following equation:
Disposal and transportation cost, $/yr = [(N)(dc) +
(N)(tc)](CRFp)
where:
N = number of 55-gal drums, V/V^, rounded to the
nearest whole number;
V = volume of packing material disposed for each control
device, m3 (ft3);
Vd = volume of 55-gal drum, 0.21 m3 (7.35 ft3);
dc = disposal cost, $50.00/drum plus 10 percent tax;23
tc = transportation cost, $40.00/drum;23 and
CRFp = capital recovery factor of 0.1628, based on an
interest rate of 10 percent and a depreciable life of
10 years for the packing material.
C. Labor coats. The annual cost of operating labor is
based on the amount of labor required to operate the control
device, plus supervision. The operator labor is based on vendor
estimates for labor hours required for each day of operation and
a labor rate of $8.37/hour.12 It was assumed that 0.25 hour per
day of operator labor is required for chevron-blade mist
eliminators, and 0.5 hour per day of operator labor is required
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for packed-bed scrubbers. The operator labor is independent of
the control device size and the number of operating hours per day
because the amount of time required to inspect and start up the
control device is not a function of its size or how long it
operates. The supervisor labor cost is assumed to be 15 percent
of the operator labor cost.14
The annual cost of maintenance labor for each control device
is based on vendor estimates of the maintenance, hours required
per 2,000 hours of control device operation and a maintenance
labor rate of $9.2l/hr.12f13 Maintenance labor is independent of
the control device size. The amount of labor does not vary
according to the size of the control device because the amount of
time to repair damaged parts (spray nozzles, water pumps, etc.)
is independent of the size of those parts for these systems.
The operator, supervisor, and maintenance labor requirements
for each model plant were calculated based on the assumption that
the labor required to operate and maintain more than one control
device increased the labor requirement by only 30 percent instead
of by 100 percent for each additional control device. For
example, for the large hard chromium plating model plant with
chevron-blade mist eliminators with a single set of blades (which
requires a total of two control devices), the operator and
maintenance labor requirement was calculated as follows:
Operator and maintenance labor, $/yr = ($1,430)(1.3) =
$1,900 instead of ($1,430) (2) = $2,860.
D. Material costs. The material cost is based on
100 percent of the maintenance labor for each control device.14
This cost is assumed to increase 100 percent for each additional
control device for the model plants.
E. Indirect costs. The indirect costs for each model plant
include overhead, property taxes, insurance, and administration.
The overhead cost is based on 60 percent of the sum of the
operator and maintenance labor plus the material costs.14 The
property taxes, insurance, and administration are equal to
4 percent of the total capital cost.14 For example, for the
large hard chromium plating model plant with chevron-blade mist
7-7
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eliminators with a single set of blades, the indirect costs were
calculated as follows:
Indirect costs, $/yr = 0.60 [ (1.3) ($1,430) + 3($830)] +
0.04[2(45,500)] = $2,110 + $3,640 = $5,800.
F. Capital recovery costs. Capital recovery costs, which
are the costs of capital spread over the depreciable life of the
control device, were calculated using the following equation:14
CRC = [TCC] [(i{l + i}n)/({l + i}n - 1)]
where:
CRC = capital recovery cost, $/yr;
TCC = total capital cost, $;
i = annual interest rate, 10 percent; and
n = depreciable life, 20 years.
For example, for the large hard chromium plating model plant with
chevron-blade mist eliminators with a single set of blades, the
capital recovery costs were calculated as follows:
CRC = [$91,000] [(0.10{1 + 0.10}20)/({1 + 0.10}20 - 1) ]
CRC = $10,600.
G. Chromic acid recovery credits. The chromic acid
recovery credits are calculated based on the estimated removal
efficiency for chevron-blade mist eliminators and packed-bed
scrubbers and the assumption that 100 percent of the chromic acid
captured by the control device is recovered. The chromic acid
recovery credit is calculated using the following equation:
Chromic acid recovery credit, $/yr = (ER) (Eff) (1.923) (C)
where:
ER = uncontrolled hexavalent chromium emission rate per
plant, kg/yr (Ib/yr);
Eff = efficiency of control device, decimal percent;
1.923 = ratio of chromic acid molecular weight (100) to
hexavalent chromium molecular weight (52); and
C = cost of chromic acid (Cr03), $3.28/kg ($1.49/lb)-11
7.2.1.2 Mesh Pad Mist Eliminators. Capital cost estimates
and operating parameters for the four different sizes of mesh-pad
mist eliminators specified for the model plants were obtained
from the control device vendor designated as Vendor I.2"4
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Operating parameters used to calculate annualized costs provided
by this vendor include the fan and washdown water pump
horsepower, washdown frequency, water consumption rates,
maintenance and operating labor hours required to operate and
maintain the control device, and .the life expectancy of the
devices.
7.2.1.2.1 Capital costs. The capital costs include the
purchase cost of the control device and auxiliaries such as inlet
and outlet transition zones, exhaust fans and motors, washdown
pumps and motors, and stacks; direct installation costs for
electrical panels and wiring, instrumentation and controls, and
piping; indirect costs for erection, engineering services,
contractor fees, and contingencies; and startup costs.
Installation costs are based on the assumptions that the control
device would be installed on the roof of the plating shop, that
the roof is 6.1 m (20 ft) high, and that the roof would require
no major structural modifications to support the weight of the
control device. The purchased equipment cost also includes taxes
and freight costs, which are assumed to be 3 and 5 percent,
respectively, of the base equipment cost.14 The startup cost is
assumed to be 1 percent of the purchased equipment cost.14
Ductwork requirements for mesh pad mist eliminator systems
are greater than for other control devices. The type of mesh-pad
mist eliminators upon which the cost estimates are based are
designed to handle a maximum gas flow rate of 340 m /min
(12,000 ft3/min), whereas other control devices have maximum gas
flow rates of approximately 1,700 m3/min (60,000 ft3/min).
Because of this lower limit, control by mesh-pad mist eliminators
requires the use of multiple small units rather than one large
unit. Consequently, additional ductwork is required to connect
these multiple units to the main ventilation system. Therefore,
the cost estimates presented in this section include costs
associated with the multiple units as well as an incremental
ductwork cost to cover the additional ductwork expense.
Schematics of the ventilation and ductwork configurations are
presented in Chapter 5.
7-9
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Installation costs for each model plant include the direct
installation costs of each unit and an indirect fixed cost of
$7,000 that covers the cost of engineering services, contractor
fees, and contingencies. The indirect cost is a fixed fee that
is applied on a per-plant basis and does not vary with the number
of control systems. Therefore, model plant installation costs
were computed as the direct installation cost of the unit plus
$7,000.
7.2.1.2.2 Annualized costs. Annualized costs include
direct operating costs such as utilities; operator, supervisor,
and maintenance labor and maintenance materials; mesh pad
replacement (including disposal costs for old pads); indirect
operating costs such as overhead, property taxes, insurance, and
administration; and capital recovery costs.
A. Utility costs. Utility costs include the costs of
electricity and water required to operate the mesh-pad mist
eliminators. Annual electrical costs result from the additional
fan horsepower needed to overcome the pressure drop added to the
ventilation system by the control device in addition to the
horsepower needed to operate the water pumps for the washdown
system. The incremental fan electrical costs were calculated
using the equation given in Section 7.2.1.1.2-A (annualized
utility costs for chevron-blade mist eliminators and packed-bed
scrubbers).
The washdown water pumps are assumed to operate about
5 minutes per 8-hr shift. The pump electrical costs were then
calculated based on the following equation:
Pump electrical cost, $/yr = [(0.746 kW/hp)(hp)(tp)(tcd)](c)
where:
kW = kilowatt;
hp = horsepower requirement, hp;
tp = operating time of pump per hour of control device
operation, 0.010 hr/hr;
tccj = operating time of control device, hr/yr; and
c = electrical cost, $0.0461/kWh.9
7-10
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For the purposes of this analysis, it was assumed that the
washdown water is recycled to the process, as is typically the
case. The amount of washdown water required and the frequency of
washdown was provided by Vendor I for each size of mesh-pad unit.
The water costs for mesh-pad mist eliminators were calculated
using the following equation:
Water cost, $/yr = [(V)(f)(S)](c)
where:
V = volume of washdown water, L(gal);
f = frequency of washdown, No. of times/8-hr shift;
S = number of 8-hr shifts per year, No./yr; and
c = water cost, $0.20/1,000 L ($0.77/1,000 gal).10
B. Replacement costs. Mesh pad replacement costs were
included because the life of the pads is less than the life of
the control device. Vendor I estimated that most facilities will
need to replace the mesh pads every 4 years. The mesh pad
material is estimated to cost approximately $10,600/m3 ($300/ft3)
of material.4 Annualized mesh pad replacement costs include the
replacement cost of the pads and the transportation and disposal
costs associated with the used pads. The replacement costs of
the pads were calculated based on the following equation:
Replacement cost, $/yr = [(V)(c)](CRF )
where:
V = volume of pad material required for each control
device, m3 (ft3);
c = cost of pad material, $10,600/m3 ($300/ft3)4; and
CRF_ = capital recovery factor of 0.3154, based on an
interest rate of 10 percent and a depreciable life
of 4 years for the mesh pads.
The transportation and disposal costs for the mesh pad
material were calculated based on the following equation:
Transportation and disposal cost, $/yr
= [(N) (dc) + (N) (tc)] (CRFp)
where:
N = number of 55-gal drums, V/V^, rounded to the
nearest whole number;
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V = volume of pad material disposed for each control
device, m3 (ft3);
Vd = volume of 55-gal drum, 0.21 m3 (7.35 ft3);
dc = disposal cost, $50.00/drum plus 10 percent tax;23
tc = transportation cost, $40.00/drum;23 and
CRF = capital recovery factor of 0.3154, based on an
interest rate of 10 percent and a depreciable life
of 4 years for the pad material.
C. Labor costs. The annual cost of operating labor is
based on the amount of labor required to operate the control
device, plus supervision. The operator labor is based on vendor
estimates for labor hours required for each day of operation and
a labor rate of $8.37/hr.12 The operator labor is independent of
the control device size and the number of operating hours per day
because the amount of time required to inspect and start up the
control device is not a function of its size or how long it
operates. The supervisor labor cost is assumed to be 15 percent
of the operator labor cost.14
The annual cost of maintenance labor for each control device
is based on vendor estimates of the maintenance hours required
per 2,000 hr of operation and a maintenance labor rate of
$9.21/hr.12;13 Maintenance labor is independent of the control
device size. The amount of maintenance labor does not vary
according to the size of the control device because the amount of
time to repair damaged parts (spray nozzles, water pumps, etc.)
is independent of the size of those parts for these systems.
The operator, supervisor, and maintenance labor requirements
for each model plant were calculated based on the assumption that
the labor required to operate and maintain more than one control
device increased the labor requirement by only 30 percent instead
of by 100 percent for each additional control device. An example
of a calculation for operator and maintenance labor is given in
Section 7.2.1.1.2-C.
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D. Material costs. The annual cost of materials is assumed
to be 100 percent of the maintenance labor cost.14 The material
cost was assumed to increase 100 percent for each additional
control device for the model plants.
E. Indirect costs. Indirect costs include overhead,
property taxes, insurance, and administration. Overhead cost is
set at 60 percent of the sum of the operator and maintenance
labor plus the material costs.14 Property taxes, insurance, and
administration equal 4 percent of the total capital cost.14 An
example of a calculation for indirect costs is given in
Section 7.2.1.1.2-E.
F. Capital recovery costs. Capital recovery costs, which
are the costs of capital spread over the depreciable life of the
control device, were calculated using the following equation:14
CRC = [TCC]{[i(l + i)n]/[(l + i)n - 1]}
where:
CRC = capital recovery cost, $/yr;
TCC = total capital cost, $;
i = annual interest rate, 10 percent; and
n = depreciable life, 10 yr.
For example, for the small hard chromium plating model plant with
a mesh-pad mist eliminator, the capital recovery costs were
calculated as follows:
CRC = [$23,000] { [0.10(1 + 0.10)10] ]/[(! + 0.10)10 - 1]}
CRC = $3,800.
G. Chromic acid recovery credits. Chromic acid recovery
credits are calculated based on the estimated removal efficiency
for mesh-pad mist eliminators and the assumption that 100 percent
of the chromic acid captured by the control device is recovered.
The chromic acid recovery credit is calculated using the equation
presented in Section 7.2.1.1.2-G.
7.2.1.3 Trivalent Chromium Process. Cost data were
obtained from four vendors of trivalent chromium plating
baths.5"** Two types (single cell and double cell) of trivalent
chromium processes are currently marketed. The capital cost
7-13
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estimates developed for the model plants are representative of
both processes and are based on a compilation of cost data
obtained from the four vendors.
7.2.1.3.1 Capital costs. Capital cost information was
obtained for the two model tanks (42 ft2 and 72 ft2 of surface
area) that are used to configure the model plants. Capital costs
include direct costs for new equipment, installation, and startup
plus indirect costs, taxes, and freight charges. New equipment
requirements include ampere-hour controller(s), anode boxes, a
plating bath filtering system, and chillers. The filtering
system and chillers are optional equipment purchases. Chillers
are required for some operations where parts are plated at high
current densities and the production load is heavy or for
operations where the temperature of the cooling water is too high
to maintain the bath within its normal operating temperature
range. Filtering systems are usually recommended to help control
plating bath contaminants. The startup cost includes the cost of
the initial trivalent chromium plating solution and the initial
cost of the passivation solution. Installation costs, based on
data obtained from plants, are estimated to be 15 percent of the
purchased equipment cost for new operations. Indirect costs for
new operations are estimated to be 31 percent of the purchased
equipment cost and cover costs associated with engineering and
supervision, process startup, and contingencies.24 Taxes and
freight charges were estimated at 3 and 5 percent, respectively,
of the base equipment cost.25
7.2.1.3.2 Annualized costs. A cost model was developed to
compare plating line costs (total cost to operate a plating line)
for the hexavalent and trivalent chromium processes. In
developing the model, emphasis was placed on operational factors
that differ between the two processes and that affect overall
production costs. These factors include differences in chemical
usage and cost, production efficiency, operation and maintenance
requirements, and wastewater treatment requirements. Information
on these factors was obtained from facilities that use the
hexavalent or trivalent chromium process, from vendors that
7-14
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manufacture both processes, and from firms that supply wastewater
treatment systems. The model, which is outlined in Table 7-4,
consists of 10 sections.
The first four sections (A through D) allow for the
specification of input parameters pertaining to the part being
plated, the model plant size, unit cost factors, and production
rates. The remaining six sections (E through J) contain the
mathematical expressions used to calculate the cost estimates. A
description of each section and its function in the cost model is
given below.
A. End-product (part) parameters. In this section, the
part and its plating parameters are specified. The parameters
include surface area of the part, plating time, current density,
and plating thickness. These parameters are used to calculate
the required current, in ampere-hours, needed to plate each part
or each square foot of part surface area. Ampere-hours are
obtained by multiplying the current density (amperes per square
foot) by the plating time (hours) and the surface area of the
part (square feet). The required current (ampere-hours per
square foot) is used to determine the chemical costs. For this
analysis, the current density and plating time are assumed to be
the same for both the hexavalent and trivalent chromium
processes.
B. Model plant parameters. In this section, parameters
that define the size of the plating facility are given. These
parameters include number of plating lines, annual operating
time, percent of time electrodes are energized, fan horsepower
required for the ventilation system, and chromium wastewater flow
rates. These parameters are used along with the part parameters
to determine the production capacity as well as the wastewater
treatment and fan electrical requirements.
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C. Cost factors. This section specifies the cost factors,
expressed in dollars per unit of consumption, for wastewater
treatment, process chemicals, and electricity. These factors are
used to estimate the cost of individual components that,
combined, make up the total annual plating line costs.
D. Production parameter. This section identifies the
parameters that establish the production efficiency. These
parameters include the rework rate for both processes (the
percentage of total parts produced per year that required
replating because of flaws in the original finish) and the
percent increase in productivity associated with the trivalent
chromium process. The rework rates for each process are the most
critical variables in the cost model.
Also identified in this section is the maximum annual
production rate for the hexavalent chromium process. The maximum
annual production rate is an ideal value based on the assumption
that no parts require reworking. The maximum annual production
rate considers the type of part plated and the size of the
plating tank(s). The size of the plating tank(s) limits the
number of racks that can be processed, while the part size and
plating specifications limit the number of parts that can be put
on a rack (rack population).
E. Production rates. This section of the model calculates
the production rates. The maximum annual production rate for the
trivalent chromium process is equal to the maximum annual
production rate of the hexavalent chromium process plus the
percent increase in productivity specified in Section D. The
total number of parts a facility can sell or distribute as final
end products is less than the maximum annual production rate
because of reworked parts that are replated. The number of parts
that are replated each year is equal to the maximum annual
production rate times the rework rate. Once the number of
reworked parts per year is known, the number of parts that were
plated and did not require reworking (once-through parts) and the
total annual production rate can be determined. The number of
once-through parts is equal to the maximum annual production rate
7-16
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minus twice the number of reworked parts, since all reworked
parts are plated two times. The total annual production rate is
then equal to the sum of the number of once-through parts and the
number of reworked parts. A basic assumption used in determining
the total annual production rate is that all reworked parts are
replated only once.
F. Chemical cost. This section of the model calculates the
chemical costs on a per-unit basis. Chemical costs are
calculated by multiplying the chemical cost factor ($/Ah) for
each process as specified in Section C by the amount of current
required per square foot of part surface area (Ah/ft2) as
specified in Section A. This product, in terms of dollars per
square foot, is then multiplied by the surface area of each part
to obtain the chemical cost per part. The chemical cost
difference between the two processes is then calculated and
subsequently used to determine the unit plating costs (plating
cost per part) for the trivalent chromium process.
G. Plating costs. This section provides estimates of
annual plating costs for both processes. First, the unit plating
*\
costs are calculated. The plating cost factor ($/ft^) for
hexavalent chromium plating is a known input for the type of part
selected. The unit plating cost for hexavalent chromium plating
is calculated by multiplying the plating cost factor ($/ft2) by
the surface area (ft2) of the part, or end product, to be plated.
The unit plating cost includes costs associated with process
chemicals, utilities, and maintenance and labor. The unit
plating cost for trivalent chromium is assumed to equal the unit
plating cost calculated for hexavalent chromium plus the
incremental cost for chemicals associated with the trivalent
chromium process (calculated in Section F). This assumption is
valid because the only component of unit plating costs that
differs between the two processes is the chemical cost. For both
processes, the rework unit plating cost is twice the original
plating cost because reworked parts are plated twice.
Annual plating costs for once-through and reworked parts are
calculated by multiplying the unit plating costs for once-through
7-17
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parts by the number of once-through parts and adding the result
to the product of the unit plating cost for reworked parts times
the number of reworked parts.
H. Wastewater treatment costs. In this section, the volume
of wastewater to be treated and the associated treatment costs
are calculated based on the size of the plating operations. The
volume of wastewater treated per year is the product of the
wastewater flow rate for each plating line (Section B), the
number of plating lines (Section B), and the annual operating
time (Section C). This value (gal/yr) is then multiplied by the
wastewater treatment cost factor ($/gal), specified in Section C
for each process, to yield the annual wastewater treatment costs.
I. Fan electrical costs. This section presents
calculations for fan electrical costs associated with the
operation of fans needed for exhaust ventilation. Fan electrical
costs apply only to the hexavalent chromium process because
trivalent chromium processes do not require ventilation. Annual
fan electrical costs are calculated by multiplying annual fan
electrical requirements (kWh) by the unit electrical cost ($/kWh)
specified in Section C. The fan electrical requirements are
based on the horsepower requirements for the exhaust ventilation
system and the annual facility operating hours specified in
Section B.
J. Plating line costs. Annual costs for plating,
wastewater treatment, and fan electrical requirements are summed
to obtain the total annual plating line cost. The total annual
plating line costs are then divided by the total annual
production rate for each process to obtain unit plating line
costs for each process. The unit plating line cost for the
trivalent chromium process is then subtracted from the unit
plating line cost of the hexavalent chromium process to obtain
the cost difference. This cost difference is then multiplied by
the total number of parts produced per year with the hexavalent
chromium process to yield the incremental annual cost or savings
associated with the trivalent chromium process.
7-18
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The key inputs in the cost model and the basis of these
inputs are presented in Appendix G. The rework rates for both
processes are the most critical variables influencing the total
plating line cost. The analysis on the rework rate and its
influence on the plating costs is also presented in Appendix G.
Capital recovery costs were calculated based on the
estimates of capital costs associated with the installation of
the trivalent chromium process at new facilities. Costs of
capital recovery for equipment purchases were calculated based on
the following equation:
CRC = TCC[i(l + i)n/(l + i)n - 1]
where:
CRC = capital recovery costs, $/yr;
TCC = total capital investment;
i = interest rate, 10 percent; and
n = equipment life, years.
The equipment life was estimated by a vendor of the
trivalent and hexavalent chromium processes.26 The capital
recovery costs associated with the cost of the initial trivalent
chromium solution were calculated by the same equation as above,
but, instead of the life of the equipment, a loan life of
10 years was assumed.
The incremental capital cost to install the trivalent
chromium process instead of the hexavalent chromium process
includes a credit for not having to install certain components of
the wastewater treatment system required for processing
wastewater from the hexavalent chromium processes. These credits
were spread over 10 years. These annual credits were then
subtracted from the capital recovery costs to obtain a net
capital recovery cost for each model plant.
7.2.1.4 Fume Suppressants. Cost information for the
application and maintenance of a variety of fume suppressants was
obtained from five major manufacturers.1^'1^ Cost estimates were
obtained for all three types of chemical fume suppressants
(wetting agents, foam blankets, and combinations of wetting
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agents and foam blankets). For cost purposes, the chemical fume
suppressants were classified as either permanent or temporary.
Permanent fume suppressants are those which are mainly depleted
by drag-out of the plating solution, and temporary fume
suppressants are those which are depleted mainly by decomposition
of the fume suppressant in the plating bath and, to lesser
extent, by drag-out.
Annual costs include both the material cost of the initial
makeup addition and the material cost of maintenance additions of
the fume suppressant in the plating bath(s). Initial makeup is
the addition of a fume suppressant to a plating bath not using a
fume suppressant. Maintenance additions are added periodically
after startup to maintain the fume suppressant concentration in
the bath at the recommended level. There is no capital
investment in equipment associated with the use of fume
suppressants. The makeup addition of the fume suppressant is not
considered a capital cost because it is an expendable material
and would only last a few days without frequent maintenance
additions.
Each of the five vendors contacted provided cost information
for applying their fume suppressants on the three model tanks
(42 ft2, 72 ft2, and 150 ft2 of surface area) that were used to
develop model decorative chromium plating and chromic acid
anodizing plants. Tank operating times were provided to the
vendors to ensure a common basis for the cost estimates. For
decorative chromium plating model plants, maintenance addition
cost estimates were based on operating the 42-ft2 model tank
1,600 hr/yr and the 72-ft2 model tank 4,800 hr/yr. For chromic
acid anodizing model plants, maintenance addition cost estimates
were based on operating the 42-ft2 model tank 500 hr/yr and the
150-ft2 model tank 5,760 hr/yr. The average makeup and
maintenance addition costs of both the permanent and temporary
fume suppressants for each tank were used to compute the annual
costs for the model plants.
Information received from the industry indicated that the
operating times used to develop the cost estimates were not
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representative of the tank operating times for decorative
chromium plating and chromic acid anodizing operations.
Adjustments were then made to the tank operating times, and,
subsequently, to the maintenance addition costs obtained from
vendors. An operating time adjustment ratio was developed to
correct the difference between the revised operating time of the
model tanks and the operating time upon which the maintenance
cost data were originally based. This ratio was then multiplied
by the maintenance cost calculated for each model tank to obtain
the corrected cost estimates. For example, the average temporary
fume suppressant maintenance addition cost supplied by vendors
for the 42-ft2 model tank for decorative chromium plating is
$1,200, based on a tank operating time of 1,600 hr/yr. The
revised 42-ft2 model tank in the small decorative chromium
plating model plant operates 1,200 hr/yr. Therefore, the
operating time adjustment ratio is 1,200/1,600 or 0.75, and the
annual maintenance addition cost is $900 (0.75 times $1,200).
The annual cost for each model plant was then calculated by
multiplying the number of model tanks used in the model plant by
their respective makeup and maintenance cost estimates to obtain
a total annual cost estimate for the model plant.
The annual costs do not include labor costs because the
labor required to add fume suppressants to the bath is
negligible. Chromic acid recovery credits are calculated based
on the reduction in the chromic acid plating solution lost when
chemical fume suppressants were used in the plating tank over
that when the plating tank was uncontrolled.
7.2.2 Existing Operations
7.2.2.1 Chevron-Blade Mist Eliminators. Packed-Bed
Scrubbers, and Mesh-Pad Mist Eliminators. Estimates for capital
and annualized costs to retrofit chevron-blade mist eliminators
with single and double sets of blades, single packed-bed
scrubbers, and mesh-pad mist eliminators for each hard and
decorative chromium electroplating and chromic acid anodizing
model plant were developed based on information provided by
vendors. The retrofit costs account for any necessary ductwork
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modifications as well as the removal and disposal of any existing
control device to be replaced at the facility. Actual retrofit
costs vary and depend on the particular facility, its layout, and
the presence or absence of an existing control device.
Three control device vendors provided estimates of retrofit
costs.27~29 Based on these estimates, a scaling factor of
20 percent of the installed capital costs of control for new
facilities was used to estimate retrofit capital costs for
existing facilities. The disposal and transportation costs for
existing control devices were not included in the vendor
estimates. Therefore, an additional 5 percent was added to cover
these costs. The 5 percent was based on the estimated disposal
and transportation costs for various sizes and types of control
devices. The total retrofit scaling factor is, then, 25 percent
of the installed capital cost of control for new facilities.
Annualized retrofit costs of chevron-blade mist eliminators,
packed-bed scrubbers, and mesh-pad mist eliminators are higher
than those for new facilities due to the higher capital recovery
costs and higher indirect costs. These costs are both a function
of the installed capital cost. Capital recovery costs for a
retrofit situation are higher because the installed capital cost
for retrofit is 25 percent higher. The taxes, insurance, and
administration components of the indirect costs are higher
because these costs are based on 4 percent of the capital costs.
7.2.2.2 Trivalent Chromium Process. Cost data were
obtained from four manufacturers of trivalent chromium plating
baths.5"8 Capital costs for existing operations include the
direct cost of new equipment, startup, and installation/
modification, indirect costs, taxes, and freight charges. New
equipment consists of an ampere-hour controller, tank liner,
replacement anodes and hangers, and anode boxes. The startup
(tank conversion) costs include the initial makeup cost of the
trivalent chromium plating solution, the initial makeup cost of
the passivation solution, and the disposal cost (transportation
and treatment) of the hexavalent chromium solution as a hazardous
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waste. Disposal costs were obtained from a waste management
facility.30
For existing operations, costs for installation/modification
are estimated to be 20 percent of the purchased equipment cost.24
Included in these costs are the costs for installing new
equipment, tank cleaning, and modifying the plating line,
electrical supply, or cooling system. Indirect costs are
estimated to be 31 percent of the purchased equipment cost and
include costs associated with engineering and supervision,
process startup, and contingencies. Taxes and freight charges
are estimated at 3 to 5 percent of the base equipment,
respectively. 5
Annual plating line costs associated with using the .
trivalent chromium plating process at existing operations are the
same as the costs for new operations. However, the annualized
costs are higher for existing facilities because of increased
costs for capital recovery. Capital recovery costs were higher
for existing operations because more capital was needed to modify
the existing plating line(s) than was needed to install the
trivalent chromium process rather than the hexavalent chromium
process at new facilities.
7.2.2.3 Fume Suppressants. Costs associated with using
fume suppressants at existing operations are the same as those at
new operations.
7.3 MODEL PLANT COSTS FOR HARD CHROMIUM PLATING OPERATIONS
This section presents the installed capital and annualized
costs of emission control techniques for new and existing hard
chromium plating operations. Table 7-5 presents the model plant
parameters on which the installed capital and annualized costs of
control devices are based.
7.3.1 Chevron-Blade Mist Eliminators and Single Packed-Bed
Scrubbers
7.3.1.1 Capital Costs. Table 7-6 presents total installed
capital costs including equipment, installation, and startup for
chevron-blade mist eliminators and single packed-bed scrubbers
applied to the hard chromium plating model plants. These
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estimates were compiled from information presented in Tables F-4
through F-7 of Appendix F on unit costs.
7.3.1.1.1 New operations. Installed capital costs for the
model small plant range from $22,500 for the chevron-blade mist
eliminator with a single set of blades to $36,700 for the single
packed-bed scrubber. Capital costs for the model large plant
range from $91,000 for the chevron-blade mist eliminator with a
single set of blades to $148,400 for the single packed-bed
scrubber. For a given control device, capital costs for the
model large plant are about four times higher than capital costs
for the model small plant. Capital costs for single packed-bed
scrubbers are about 60 percent higher than capital costs for
chevron-blade mist eliminators with a single set of blades and
about 50 percent higher than capital costs for chevron-blade mist
eliminators with a double set of blades.
7.3.1.1.2 Existing operations. Estimated capital costs to
retrofit a chevron-blade mist eliminator with a double set of
blades at the model small, medium, and large plants are $29,800,
$62,400, and $124,800, respectively. For the single packed-bed
scrubber, the costs are $45,900, $92,800, and $185,500,
respectively.
7.3.1.2 Annualized Costs. The annualized costs for
chevron-blade mist eliminators and single packed-bed scrubbers
for the model hard chromium plating plants are presented in
Table 7-7. The annualized cost estimates, with the exception of
the labor requirements and indirect costs, were compiled from
information presented in Tables F-8 through F-10 of Appendix F on
unit costs. The procedures for calculating labor requirements,
indirect costs, and chromic acid recovery credits are described
in Section 7.2.1.1.2.
7.3.1.2.1 New Operations. The net annualized costs
(annualized costs less chromic acid recovery credits) for the
model small plant range from $5,500 for the chevron-blade mist
eliminator with a double set of blades to $9,800 for the single
packed-bed scrubber. Net annualized costs for the model large
plant range from $20,100 for the chevron-blade mist eliminator
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with a double set of blades to $39,000 for the single packed-bed
scrubber. Net annualized costs for chevron-blade mist
eliminators with a double set of blades are 15 to 33 percent
higher than mist eliminators with a single set of blades.
7.3.1.2.2 Existing operations. The net annualized costs
for retrofitting the chevron-blade mist eliminator with a double
set of blades at the model small, medium, and large plants are
$6,400, $12,200, and $24,000, respectively. For the single
packed-bed scrubber, the costs are $11,200, $21,600, and $44,800.
7.3.2 Mesh-Pad Mist Eliminators
7.3.2.1 Capital Costs. Table 7-8 presents the total
installed capital costs including equipment, additional ductwork,
installation, and startup for mesh-pad mist eliminators applied
to the model hard chromium plating plants. These estimates, with
the exception of the additional ductwork costs, were compiled
from information presented in Table F-20 of Appendix F on the
unit costs.
7.3.2.1.1 New operations. Installed capital costs for the
mesh-pad mist eliminators range from $23,000 for the model small
plant to $124,900 for the model large plant. Capital costs for
the model large plant are about five times higher than capital
costs for the model small plant. For the model small plant,
capital costs for mesh-pad mist eliminators are 37 percent lower
than the capital costs of single packed-bed scrubbers and
3 percent lower than the capital costs of chevron-blade mist
eliminators with a double set of blades. For the model medium
plant, capital costs for mesh-pad mist eliminators are 11 percent
lower than for single packed-bed scrubbers and 33 percent higher
than those for chevron-blade mist eliminators with a double set
of blades. For the model large plant, capital costs for mesh-pad
mist eliminators are 16 percent lower than capital costs for
single packed-bed scrubbers and 25 percent higher than capital
costs for chevron-blade mist eliminators with a double set of
blades.
7.3.2.1.2 Existing operations. Estimated capital costs to
retrofit mesh-pad mist eliminators at the model small, medium,
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and large plants are $28,900, $82,500, and $156,300,
respectively.
7.3.2.2 Annualized Costs. The annualized costs for
mesh-pad mist eliminators for the model hard chromium plating
plants are presented in Table 7-9. The annualized cost
estimates, with the exception of the labor requirements and
indirect costs, were compiled from information presented in
Table F-21 of Appendix F on unit costs. The procedures for
calculating labor requirements, indirect costs, and chromic acid
recovery credits are described in Section 7.2.1.2.2.
7.3.2.2.1 New operations. The net annualized costs
(annualized costs less chromic acid recovery credits) for the
mesh-pad mist eliminator range from $8,000 for the model small
plant to $52,600 for the model large plant.
7.3.2.2.2 Existing operations. The net annualized costs
for retrofitting mesh-pad mist eliminators at the model small,
medium, and large plants are $9,200, $27,300, and $59,000,
respectively.
7.4 MODEL PLANT COSTS FOR DECORATIVE CHROMIUM PLATING OPERATIONS
This section presents the installed capital and annualized
costs of emission control techniques applied to new and existing
decorative chromium plating operations. Table 7-10 presents the
model plant parameters on which the installed capital and
annualized cost estimates of control techniques are based.
7.4.1 Single Packed-Bed Scrubbers
7.4.1.1 Capital Costs. Table 7-11 presents the total
installed capital costs including equipment, installation, and
startup for single packed-bed scrubbers applied to the model
decorative chromium plating plants. These estimates were
compiled from information presented in Table F-6 of Appendix F on
unit costs.
7.4.1.1.1 New operations. Installed capital costs for
single packed-bed scrubbers range from $36,700 for the model
small plant to $124,600 for the model large plant. Capital costs
for the model large plant are about three times higher than
capital costs for the model small plant.
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7.4.1.1.2 Existing Operations. Estimated capital costs to
retrofit single packed-bed scrubbers at the model small, medium,
and large plants are $45,900, $91,800, and $155,900,
respectively.
7.4.1.2 Annualized Costs. .The annualized costs for single
packed-bed scrubbers for the decorative chromium plating model
plants are presented in Table 7-12. The annualized cost
estimates, with the exception of the labor requirements and
indirect costs, were compiled from information presented in
Table F-10 of Appendix F on unit costs. The procedures for
calculating labor requirements, indirect costs, and chromic acid
recovery credits are described in Section 7.2.1.1.2.
7.4.1.2.1 New operations. The net annualized costs
(annualized costs less chromic acid recovery credits) for the
single packed-bed scrubber range from $10,100 for the model small
plant to $40,400 for the model large plant.
7.4.1.2.2 Existing operations. The net annualized costs
for retrofitting single packed-bed scrubbers at the model small,
medium, and large plants are $11,500, $24,400, and $45,200,
respectively.
7.4.2 Mesh-Pad Mist Eliminators
7.4.2.1 Capital Costs. Table 7-13 presents total installed
capital costs including the equipment, additional ductwork,
installation, and startup for mesh-pad mist eliminators applied
at the model decorative chromium plating plants. These
estimates, with the exception of additional ductwork costs, were
compiled from information presented in Table F-20 of Appendix F
on unit costs.
7.4.2.1.1 New operations. Installed capital costs for
mesh-pad mist eliminators range from $23,000 for the model small
plant to $87,200 for the model large plant. Capital costs for
the model large plant are about four times higher than capital
costs for the model small plant. Capital costs of mesh-pad mist
eliminators are 30 to 47 percent lower than the capital costs of
single packed-bed scrubbers.
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7.4.2.1.2 Existing operations. Estimated capital costs to
retrofit mesh-pad mist eliminators at the model small, medium,
and large plants are $28,900, $49,000, and $109,100,
respectively.
7.4.2.2 Annualized Costs. The annualized costs for
mesh-pad mist eliminators for the decorative chromium plating
model plants are presented in Table 7-14. The annualized cost
estimates, with the exception of the labor requirements and
indirect costs, were compiled from information presented in
Table F-21 of Appendix F on unit costs. The procedures for
calculating labor requirements, indirect costs, and chromic acid
recovery credits are described in Section 7.2.1.2.2.
7.4.2.2.1 New operations. The net annualized costs
(annualized costs less chromic acid recovery credits) for mesh-
pad mist eliminators range from $8,300 for the model small plant
to $42,800 for the model large plant.
7.4.2.2.2 Existing operations. The net annualized costs
for retrofitting mesh-pad mist eliminators at the model small,
medium, and large plants are $9,500, $18,900, and $47,300,
respectively.
7.4.3 Chemical Fume Suppressants
Table 7-15 presents the net annualized costs (annualized
costs less chromic acid recovery credits) of fume suppressants
for the model decorative chromium electroplating plants. There
is no capital investment associated with using fume suppressants
as a control technique. For temporary fume suppressants, net
annual costs range from $900 for the model small plant to $11,000
for the model large plant. Net annual costs for permanent fume
suppressants range from $1,000 for the model small plant to
$17,200 for the model large plant. Annual costs associated with
using fume suppressants are the same for new and existing
operations.
7.4.4 Trivalent Chromium Process
7.4.4.1 Capital Costs.
7.4.4.1.1 New operations. The incremental capital costs of
installing the trivalent chromium plating process rather than the
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conventional hexavalent chromium plating process at new
facilities are presented in Table 7-16. Total capital costs are
$44,800 for the model small plant and $306,000 for the model
large plant. Since using the trivalent chromium process
eliminates the need for a hexavalent chromium reduction step in
the wastewater treatment system, a cost savings is achieved. The
capital cost for the hexavalent chromium reduction step was
obtained from a 1985 EPA document.31 Treatment equipment and
ancillary items no longer required for reduction purposes were
identified, and their associated costs were estimated. In
addition, the volume of process wastewater to be treated was
estimated for each model plant based on information presented in
the development document for effluent guidelines and standards.
The cost savings associated with eliminating the hexavalent
chromium reduction step ranged from $19,600 for the model small
plant to $41,400 for the model large plant. After adding in this
savings, the net capital costs of a trivalent chromium process
for the model small plant would be reduced to $25,200, and net
capital costs for the model medium and large plants would be
reduced to $60,000 and $264,600, respectively.
7.4.4.1.2 Existing operations. The capital costs
associated with converting a hexavalent chromium process to a
trivalent chromium process for each model plant are presented in
Table 7-17. These costs range from $66,900 for the model small
plant to $565,500 for the model large plant.
7.4.4.2 Annualized Costs. The difference in annual plating
line costs between the hexavalent and trivalent chromium
processes was calculated for three different end products using
the cost model detailed in Table 7-4. These three end products
were faucets, ratchets, and bumpers. For the purpose of this
analysis, the model small plant was assumed to be plating the
ratchets, the model medium plant the faucets, and the model large
plant the bumpers. Because the plating line costs are highly
dependent on the reject or rework rate for the hexavalent
chromium processes (see Appendix G) and because of the wide range
of rework rates encountered in the industry, three comparative
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cost scenarios representative of the full range of rework rates
were developed. In contrast, rework rates reported for the
trivalent chromium process are fairly uniform. Consequently, for
each scenario, the trivalent chromium rework rate was set at
l percent, while the rework rate for the hexavalent chromium
'process varied. In the first scenario, the rework rates for the
hexavalent chromium process were set at the values provided by
individual plants that actually plate the parts selected. The
corresponding hexavalent chromium rework rates for the first
scenario were 1, 3, and 15 percent for faucets, ratchets, and
bumpers, respectively. In the second scenario, the rework rate
for all parts was set at the average rework rate (7 percent)
provided by the hexavalent chromium plants. In the third
scenario, the individual hexavalent chromium process rework rates
were set at a value that yields a zero cost difference between
the two processes. The hexavalent chromium rework rates for this
third scenario were 2.85, 4.5, and 6.75 percent for ratchets,
faucets, and bumpers, respectively. The results from the cost
model for each of the three scenarios are presented in
Tables 7-18 through 7-20.
The incremental annualized costs associated with the
trivalent chromium process were calculated by adding the capital
recovery costs to the total annual plating cost difference
between the two processes. Since three different scenarios were
used to determine the incremental annual plating cost difference
associated with the trivalent chromium process, there are also
three separate incremental annualized costs based on these
scenarios. The capital recovery costs are presented in
Table 7-21, and the resulting incremental annualized costs are
presented in Table 7-22.
7.5 MODEL PLANT COSTS FOR CHROMIC ACID ANODIZING OPERATIONS
This section presents the installed capital and annualized
costs of emission control techniques for new and existing chromic
acid anodizing operations. Table 7-23 presents the model plant
parameters on which the installed capital and annualized costs of
control techniques are based.
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7.5.1 Chevron-Blade Mist Eliminators and Single Packed-Bed
Scrubbers
7.5.1.1 Capital Costs. Table 7-24 presents total installed
capital costs including equipment, installation, and startup for
chevron-blade mist eliminators with a single set of blades and
single packed-bed scrubbers applied to the model chromic acid
anodizing plants. These estimates were compiled from information
presented in Tables F-4 and F-6 of Appendix F on unit costs.
7.5.1.1.1 New operations. Installed capital costs for the
model small plant range from $22,500 for the chevron-blade mist
eliminator with a single set of blades to $36,700 for the single
packed-bed scrubber. Capital costs for the model large plant
range from $48,600 for the chevron-blade mist eliminator with a
single set of blades to $78,700 for the single packed-bed
scrubber. Capital costs of either control device for the model
large plant are about twice those of the model small plant.
7.5.1.1.2 Existing Operations. Estimated capital costs to
retrofit single packed-bed scrubbers are $45,900 at the model
small plant and $98,400 for the model large plant.
7.5.1.2 Annualized Costs. Table 7-25 presents the
annualized costs for chevron-blade mist eliminators with a single
set of blades and single packed-bed scrubbers for the model
chromic acid anodizing plants. The cost estimates, with the
exception of labor requirements and indirect costs, were compiled
from information presented in Tables F-8 and F-10 of Appendix F
on the unit costs. Procedures for calculating labor
requirements, material cost, indirect costs, and chromic acid
recovery credits are described in Section 7.2.1.1.2.
7.5.1.2.1 New operations. The net annualized costs
(annualized costs less chromic acid recovery credits) for the
single packed-bed scrubber are $10,100 for the model small plant
and $25,500 for the model large plant.
7.5.1.2.2 Existing operations. The net annualized costs
for retrofitting single packed-bed scrubbers are $11,500 for the
model small plant and $28,600 for the model large plant.
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7.5.2 Mesh-Pad Mist Eliminators
7.5.2.1 Capital Costs. Table 7-26 presents the total
installed capital costs of mesh-pad mist eliminators for the
model chromic acid anodizing plants. These estimates, with the
exception of the additional ductwork costs, were compiled from
information presented in Table F-20 of Appendix F for unit costs.
As discussed in Section 7.2.1.2.1, additional ductwork is
required to accommodate the low air flows associated with mesh-
pad mist eliminators.
7.5.2.1.1 New operations. Installed capital costs for
mesh-pad mist eliminators range from $23,000 for the model small
plant to $91,700 for the model large plant. Capital costs for
the model large plant are about four times higher than capital
costs for the model small plant. Capital costs of mesh-pad mist
eliminators for the model small plant are about 40 percent lower
than capital costs of single packed-bed scrubbers. For the model
large plant, capital costs of mesh-pad mist eliminators are about
20 percent higher than capital costs of single packed-bed
scrubbers.
7.5.2.1.2 Existing operations. Estimated capital costs to
retrofit mesh-pad mist eliminators are $28,900 for the model
small plant and $114,900 for the model large plant.
7.5.2.2 Annualized Costs. Table 7-27 shows the annualized
costs for mesh-pad mist eliminators for the model chromic acid
anodizing plants. The annualized cost estimates, except for
labor requirements and indirect costs, were compiled from
information presented in Table F-21 of Appendix F on unit costs.
Procedures for calculating labor requirements, indirect costs,
and chromic acid recovery credits are described in
Section 7.2.1.2.2.
7.5.2.2.1 New operations. The net annualized costs
(annualized costs less chromic acid recovery credits) for mesh-
pad mist eliminators range from $8,300 for the model small plant
to $39,800 for the model large plant.
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7.5.2.2.2 Existing operations. The net annualized costs
for retrofitting mesh-pad mist eliminators are $9,500 for the
model small plant and $44,400 for the model large plant.
7.5.3 Chemical Fume Suppressants
Table 7-28 presents the net -annualized costs (annualized
costs less chromic acid recovery credits) of permanent fume
suppressants for the chromic acid anodizing model plants. Cost
data were provided only for permanent fume suppressants. There
is no capital investment associated with using fume suppressants
as a control technique. Net annual costs for permanent fume
suppressants range from $1,600 for the model small plant to
$4,300 for the model large plant. Annual costs associated with
using fume suppressants for new and existing operations are the
same.
7.6 TOTAL INDUSTRY COSTS
This section presents estimates of total aggregate costs,
both capital and annualized, associated with applying each
control option industrywide. Nationwide capital and annualized
costs for each control option are based on a combination of new
facility and existing facility costs for the model plants, the
estimated number of operations nationwide of each size model
plant, and the percentage of operations controlled by a specific
control technique.
For operations controlled by a specific control technique
under Option I, model plant costs representative of new facility
costs were used to determine the nationwide baseline control
costs. For the other control options, existing facility costs
(retrofit costs) were used for operations that went from one
control technique under Option I to another control technique
under one of the other options. New facility costs were used for
operations that went from uncontrolled under Option I to a
specified control technique under one of the other options and
for operations for which the specified control technique is the
same under Option I as it would be under other options.
Cost effectiveness is the annual cost to control 1 Mg of
hexavalent chromium. The cost effectiveness of a control option
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is determined by dividing the incremental annualized cost
estimate by the incremental annual hexavalent chromium emission
reduction. Cost effectiveness values were computed for each
control option compared to the baseline level and compared to
each of the next-less-stringent control options.
The profile of this industry is dynamic, so no attempt was
made to quantify fifth-year costs. It is anticipated that the
total number of operations nationwide will not change in the next
5 years. If anything, a number of existing small operations may
be replaced by new larger operations. Because new facility costs
are less than existing facility (retrofit) costs, this
replacement could result in lower nationwide costs in the fifth
year.
7.6.1 Hard Chromium Electroplating
7.6.1.1 Capital and Annualized Costs Attributable to Each
Control Option. Nationwide capital and annualized costs
attributable to each control option are presented in Table 7-29.
Control Option I is the no-action, or baseline, option that would
require no additional controls over existing levels. Table 7-5
presents the hard chromium plating model plant parameters and
baseline conditions upon which Option I was based.
Costs associated with Control Option I are based on new
facility costs for the operations controlled by a specified
control technique. For example, for the small hard chromium
plating model plants under Option I, 30 percent of the operations
(324 operations) are uncontrolled, 30 percent of the operations
(324 operations) are controlled by chevron-blade mist eliminators
with a single set of blades, and 40 percent (432 operations) are
controlled by single packed-bed scrubbers. The total new
facility capital cost of a chevron-blade mist eliminator with a
single set of blades and a single packed-bed scrubber for the
model small plant is $22,500 and $36,700, respectively. The net
annualized costs for these control techniques are $4,800 and
$9,800, respectively. The nationwide capital and net annualized
costs for small hard chromium plating operations are calculated
as follows:
7-34
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Capital Costs:
(324 operations)($0.00) = $ 0.00
(324 operations) ($22,500) = $ 7.29 million
(432 operations) ($36,700) = $15.85 million
Total capital costs = $23.14 million
Annualized Costs:
(324 operations) ($0.00) = $0.00
(324 operations) ($4,800) = $1.56 million
(432 operations) ($9,800) = $4.23 million
Total net annualized costs = $5.79 million
Similar calculations were performed for the model medium and
large plants. The total nationwide capital and annualized costs
for hard chromium plating operations under Control Option I are
the sums of the nationwide totals for each plant size, which are
$49.57 million and $11.93 million, respectively.
Costs associated with Control Option II are based on the use
of chevron-blade mist eliminators with a double set of blades
that reduce uncontrolled emissions by 95 percent. For the model
small plants under Option II, the 30 percent (324 operations)
that were uncontrolled under Option I would install chevron-blade
mist eliminators with a double set of blades, and new facility
costs would apply. For the 30 percent (324 operations) that were
controlled under Option I by chevron-blade mist eliminators with
a single set of blades, retrofit costs for chevron-blade mist
eliminators with a double set of blades are used. The other
40 percent (432 operations) are controlled by single packed-bed
scrubbers under Option I. Because scrubbers reduce uncontrolled
emissions by 97 percent, these operations would not convert to
chevron-blade mist eliminators with a double set of blades and,
therefore, new facility costs for single packed-bed scrubbers are
used.
For a chevron-blade mist eliminator with a double set of
blades, the total new facility capital cost is $23,800, and the
total retrofit capital cost is $29,800. The net annualized costs
are $5,500 and $6,400, respectively. The total new facility
capital cost for a single packed-bed scrubber is $36,700. The
7-35
-------
net annualized costs are $9,800. Therefore, the nationwide
capital and net annualized costs for small hard chromium plating
operations under Control Option II are calculated as follows:
Capital Costs:
(324 operations)($23,800) = $ 7.71 million
(324 operations) ($29,800) = $ 9.66 million
(432 operations) ($36,700) = $15.85 million
Total capital costs = $33.22 million
Annualized Costs:
(324 operations) ($5,500) = $1.78 million
(324 operations) ($6,400) = $2.07 million
(432 operations) ($9,800) = $4.23 million
Total net annualized costs = $8.09 million
Similar calculations were performed for the model medium and
large plants.
Costs associated with Control Option Ilia are based on the
use of single packed-bed scrubbers that reduce uncontrolled
hexavalent chromium emissions by 99 percent. Costs associated
with Control Option Illb are based on the use of mesh-pad mist
eliminators that also reduce uncontrolled emissions by
99 percent. These costs were calculated using the procedures
described above.
7.6.1.2 Cost Effectiveness. The cost-effectiveness values
for the control options are summarized in Table 7-30.
7.6.2 Decorative Chromium Electroplating
7.6.2.1 Capital and Annualized Costs Attributable to Each
Control Option. Nationwide capital and annualized costs
attributable to each control option are presented in Table 7-31.
Table 7-10 presents the decorative chromium plating model plant
parameters and baseline conditions upon which Option I was based.
Costs associated with Option Ila are based on the use of single
packed-bed scrubbers, and costs associated with Option lib are
based on the use of mesh-pad mist eliminators. Single packed-bed
scrubbers and mesh-pad mist eliminators are assumed to reduce
uncontrolled hexavalent chromium emissions from decorative
chromium plating operations by 97 percent. Costs associated with
7-36
-------
Option III are based on the use of chemical fume suppressants,
which are assumed to reduce uncontrolled chromium emissions by
99.5 percent. Cost impacts for fume suppressants were based on
the cost of the permanent fume suppressant presented for the
model plants in Table 7-15. Costs associated with Option IV are
based on the use of the trivalent chromium plating process, which
reduces uncontrolled hexavalent chromium emissions by
100 percent. Costs for Option IV are presented for three
production scenarios, each representing different rework rates.
7.6.2.2 Cost Effectiveness. The cost-effectiveness values
for the control options are summarized in Table 7-32.
7.6.3 Chromic Acid Anodizing
7.6.3.1 Capital and Annualized Costs Attributable to Each
Control Option. Nationwide capital and annualized costs
attributable to each control option are presented in Table 7-33.
Table 7-23 presents the chromic acid anodizing model plant and
the baseline conditions upon which Option I was based. Costs
associated with Option Ila are based on the use of single packed-
bed scrubbers, and costs associated with Option lib are based on
the use of mesh-pad mist eliminators. These two control devices
are assumed to reduce uncontrolled hexavalent chromium emissions
from chromic acid anodizing operations by 97 percent. Costs
associated with Option III are based on the use of chemical fume
suppressants, which reduce uncontrolled emissions by
99.5 percent. Fume suppressant cost impacts are based on the
cost of permanent fume suppressants (presented in Table 7-15).
7.6.3.2 Cost Effectiveness. The cost-effectiveness values
for the control options are summarized in Table 7-34.
7.7 OTHER COST CONSIDERATIONS
7.7.1 Water Pollution Control Act
Water pollution control costs associated with the control
options based on the use of mist eliminators and scrubbers are
not expected to increase over those associated with the
respective baseline options. The scrubber water and mist
eliminator washdown water typically are discharged to the plating
or anodizing tank to make up for evaporation losses. The
7-37
-------
discharging of scrubber water and mist eliminator washdown water
to the plating or anodizing tank reduces plant wastewater
treatment costs and recovers chromic acid lost by misting. Some
operations, especially decorative chromium plating operations,
operate wastewater treatment systems. In decorative chromium
plating operations, the scrubber often has two functions: (1) to
reduce chromic acid emissions from the plating tank and (2) to
evaporate rinse water. The rinse tank following the decorative
chromium plating tank is used as the source of the scrubber
water; as the water evaporates in the scrubber, the chromium
concentration increases. This helps to keep the chromium
concentration in the rinse tanks low but also increases the
chromium concentration in the scrubber effluent before it goes to
wastewater treatment, reducing the overall wastewater treatment
burden of the plant. However, the amount of control device
effluent relative to the total amount of wastewater associated
with the plating operations is low (less than 2 percent).1"3'32
Therefore, treatment costs attributable to the control options
are considered to be insignificant.
7.7.2 Resource Conservation and Recovery Act
Under Control Option IV, decorative chromium plating
operations would incur hazardous waste disposal costs as a result
of replacing a hexavalent with a trivalent chromium plating
process. Replacing of the hexavalent chromium process requires
proper disposal of the hexavalent chromium plating solution. The
hexavalent chromium plating solution is considered hazardous
waste under the provisions of RCRA, and, therefore, the solution
must be sent to a hazardous waste management facility for proper
treatment and disposal. The hazardous waste disposal costs
incurred by the model plants under Option IV are estimated to be:
7-38
-------
Model small plant: $3,700 for 6,500 L (1,730 gal) of waste;
Model medium plant: $7,400 for 13,100 L (3,460 gal) of
waste; and
Model large plant: $41,000 for 86,700 L (22,900 gal) of
waste.
For decorative chromium electroplating operations, there are
2,240 small plants, 420 medium plants, and 140 large plants.
Thus, the nationwide hazardous waste disposal cost attributable
to Option IV is estimated to be $17.1 million.
Implementing the control options based on the use of
packed-bed scrubbers or mesh-pad mist eliminators would also
result in an increase in hazardous waste disposal costs.
Scrubber packing materials are replaced approximately every
10 years and mesh pads every 4 years. The hexavalent chromium-
contaminated packing and pads must be treated and disposed of by
a hazardous waste management facility. The volumes of waste
associated with disposal are shown in Chapter 6, Tables 6-13
through 6-15. Tables 7-35 through 7-37 present the annualized
disposal costs attributable to these control options.
The following example shows how the transportation and
disposal costs were estimated. This example uses Option Ilia
(single packed-bed scrubbers) for the model large plant of the
hard chromium electroplating operations:
The model large plant uses two 990 m3/min (35,000 ft /min)
single packed-bed scrubber units. These units each contain
2.1m3 (74 ft3) of packing material. At 0.21 m3 (7.35 ft3) per
55-gal drum, 11 drums (considering void space) are needed to
contain the bed packing material from each unit. Total disposal
costs are $40 per drum for transportation and $50 (plus
10 percent tax) per drum for disposal, or $95 per drum.^3 The
total transportation and disposal costs for scrubber packing
material for the model 'large plant are:
(2 units)(11 drums/unit)($95/drum) = $2,090.
7-39
-------
Assuming a 10-year life for packing material, the capital
recovery factor is 0.1628. Under Option Ilia for hard chromium
plating operations, there would be 150 large operations using
single packed-bed scrubbers. Therefore, the nationwide
annualized disposal costs for packing material for large
operations would be:
(0.1628)($2,090/operation)(150 operations) = $51,000.
Similar calculations were performed for each plant size in each
control option for hard and decorative chromium plating
operations and chromic acid anodizing operations for scrubber
packing material. For operations using mesh-pad mist
eliminators, calculations were similar, except that the capital
recovery factor is based on a 4-year life and is equal to 0.3154.
At the time of this writing, RCRA legislation is being
considered that would affect the disposal of chromium-
contaminated waste in landfills. At this time, solid debris
(e.g., scrubber bed packing and mesh-pad material) that is
contaminated with chromium may be placed in a Class I landfill
without pretreatment. Implementation of RCRA pretreatment
standards for chromium-contaminated debris could significantly
impact the costs associated with disposal of these material. In
Chapter 6, estimates of solid waste generation associated with
the use of packed-bed scrubbers and mesh-pad mist eliminators
were made using the assumption that the waste material is
compacted to 50 percent of its original volume. While compaction
for disposal is typically practiced in the industry, disposal
costs presented in this document have been estimated without the
compaction assumption. These "worst-case" cost estimates were
made in order to compensate for future increases in disposal
costs attributable to the RCRA legislation.
For hard chromium electroplating operations, nationwide
annualized disposal costs attributable to the use of packed-bed
scrubbers or mesh-pad mist eliminators range from $76,000/yr for
Option I to $190,100/yr for Option Ilia. Because Option I
7-40
-------
represents baseline conditions (i.e., these operations already
incur these disposal costs), costs for Option I are subtracted
from the costs for other control options in order to determine
disposal costs attributable to implementation of a particular
control option. Therefore, disposal costs attributable to
Option II are zero ($76,000/yr for Option II minus $76,000/yr for
Option 1}. Disposal costs attributable to the implementation of
Option Ilia or Option Illb are $114,100/yr or $l04,800/yr,
respectively.
Nationwide annualized disposal costs attributable to the use
of packed-bed scrubbers or mesh-pad mist eliminators for
decorative chromium plating operations range from $126,000/yr for
Option I to $168,000/yr for Option Ila. Subtracting the costs
for Option I, incremental disposal costs attributable to the
implementation of Option Ila are $42,000/yr and of Option lib,
$34,000/yr. For chromic acid anodizing operations, incremental
disposal costs attributable to the implementation of Option Ila
are $36,200/yr and of Option lib, $35,100/yr.
There are hazardous waste transportation and disposal costs
associated with retrofitting or replacing of control devices at
existing operations. The cost to dispose of control devices at
existing operations was estimated as 5 percent of the cost of a
new control device.
No other control options considered in these analyses are
expected to increase costs to the electroplating and anodizing
operations under RCRA because the.pollution control techniques
upon which the control options are based will not increase the
amount of hazardous wastes currently generated by electroplating
or anodizing operations.
7.7.3 Occupational Safety and Health Administration Act
The chromium electroplating and anodizing shops considered
in these analyses are subject to the OSHA general industrial
health and safety standards as well as the OSHA regulation that
limits concentrations of chromic acid and chromates inside the
plant to a ceiling concentration of 0.1 mg/m3
(4.4 x 10"5 gr/ft3).33 Most chromium electroplating and
7-41
-------
anodizing shops already have installed ventilation systems to
comply with OSHA standards.
Costs of capture systems and ductwork necessary to comply
with the OSHA regulation for chromium are included in this
chapter for information only and are not considered to be costs
attributable to the control options. Table 7-38 presents the
capital costs of ventilation hoods and takeoffs for each of the
six tank sizes used in the model plants. Table 7-39 presents the
capital costs of ventilation hoods, takeoffs, and ductwork for
the tank(s) vented to each of the control devices. Vendor A
provided these cost data based on the ventilation hood, takeoff,
and ductwork specifications presented in Chapter 5. Table 7-40
presents the capital costs of ventilation hoods, takeoffs, and
ductwork for the model plants. Vendors B and C did not provide
cost estimates for capture systems and ductwork.
7-42
-------
TABLE 7-1. CONTROL TECHNIQUES UPON WHICH THE CONTROL OPTION
COST IMPACTS ARE BASED
Type of operation/
Control option
Control technique
Hard chromium plating
Option I (no action)
Option II
Option III
Decorative chromium plating
Option I (no action)
Option II
Option III
Option IV
Chromic acid anodizing
Option I (no action)
Option II
Option ID
Existing (baseline) level of control
• 30 percent of operations uncontrolled
• 30 percent of operations controlled by chevron-blade mist eliminators with
single sets of blades that reduce uncontrolled emissions by 90 percent
• 40 percent of operations controlled by single packed-bed scrubbers that reduce
uncontrolled emissions by 97 percent
Chevron-blade mist eliminators with a double set of blades that reduce
uncontrolled emissions by 95 percent
Single packed-bed scrubbers or mesh-pad mist eliminators that reduce
uncontrolled emissions by 99 percent
Existing (baseline) level of control
• 15 percent of operations uncontrolled
• 40 percent of operations controlled by chemical fume suppressants that reduce
uncontrolled emissions by 97 percent
• 40 percent of operations controlled by a combination of chemical fume
suppressants and packed-bed scrubbers that reduces uncontrolled emissions by
97 percent
• 5 percent of operations controlled by single packed-bed scrubbers that reduce
uncontrolled emissions by 95 percent
Single packed-bed scrubbers or mesh-pad mist eliminators that reduce
uncontrolled emissions by 97 percent
Chemical fume suppressants applied in accordance with vendor
recommendations. Uncontrolled emissions reduced by 99.5 percent
Trivalent chromium plating processes that reduce hexavalent chromium
emissions by 100 percent (technology forcing)
Existing (baseline) level of control
• 40 percent of operations uncontrolled
• 30 percent of operations controlled by chemical fume suppressants that reduce
uncontrolled emissions by 97 percent
• 10 percent of operations controlled by chevron-blade mist eliminators with a
single set of blades that reduce uncontrolled emissions by 90 percent
• 20 percent of operations controlled by single packed-bed scrubbers mat reduce
uncontrolled emissions by 95 percent
Single packed-bed scrubbers or mesh-pad mist eliminators that reduce
uncontrolled emissions by 97 percent
Chemical fume suppressants applied in accordance with vendor
recommendations. Uncontrolled emissions reduced by 99.5 percent
7-43
-------
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7-44
-------
TABLE 7 - 3 . ANNUAL OPERATING COST FACTORS
Cost categories
Cost factors
Direct operating costs
1. Operating labor
a. Operator-"-"*' -1-
b. Supervisor14
2
3
4
5
Operating materials
Maintenance
a. Labor12"14
b. Materials14
Replacement parts
Utilities
a. Electricity9
b. Water
10
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6
7
8,
9
10
,14
Overhead14
Property taxj
Insurance14
Administration14
Capital recovery14
Credits
Chromic acid recovery11
$8.37/hr
15 percent of la
As required
$9.21/hra
100 percent of 3a
As required
$0.0461/kWh13
$0.77/1,000 gal14
60 percent of la + Ib + 3a
I percent of capital cost
1 percent of capital cost
2 percent of capital cost
11.7 percent of capital
costj
or
16.3 percent of capital
cost
$3.28/kg
f-Based on 110 percent of operating labor.
kfiased on an interest rate of 10 percent and an equipment life of
20 years (for chevron-blade mist eliminators and packed-bed
scrubbers).
cBased on an interest rate of 10 percent and an equipment life
of 10 years (for mesh-pad mist eliminators).
7-45
-------
PRODUCTION FACTORS
A END-PRODUCT PARAMETERS
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7-46
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7-47
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TOTAL
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cAssumed 15.2 cm (6.0 in.)
"See Chapter 5 for derivatio
eMist eliminator with a cont
'Packed-bed scrubber with a
7-51
-------
TABLE 7-6. CAPITAL COSTS OF CHEVRON-BLADE MIST ELIMINATORS
AND SINGLE PACKED-BED SCRUBBERS FOR HARD CHROMIUM PLATING
MODEL PLANTSa
(November 1988 Dollars)
Model plant size
Chevron-blade
mist eliminator
Single set Double set
of blades of blades
Single
packed-bed
scrubber
Small13
Purchased equipment
Installation
Startup0 ,
Total capital cost0
Medium6
Purchased equipment
Installation
Startup0 ,
Total capital cost0
10,100
12,300
100
22,500
24,400
20,800
200
45,400
11,400
12,300
100
23,800
28,700
20,800
300
49,800
19,500
17,000
200
36,700
47,300
26,400
500
74,200
Largji
Purchased equipment
Installation
Startup0 ,
Total capital costa
48,800 57,400 94,600
41,700 41,700 52,900
500 600 900
91,000 99,700 148,400
aCapital costs for chevron-blade mist eliminators are from
Tables F-4 and F-5, and capital costs for scrubbers are from
Tables F-6 and F-7 in Appendix F.
°Small model plant costs for each control device type are from
Column B in Tables F-4 through F-7 in Appendix F.
°Startup costs are based on 1 percent of the purchased equipment
cost.
"Total capital cost is the sum of purchased equipment,
installation, and startup costs. Cost data were rounded to the
nearest $100.
eMedium model plant costs for each control device type are from
Column D in Tables F-4 through F-7 in Appendix F.
fLarge model plant costs for each control device type are two
times medium model plant costs.
7-52
-------
TABLE 7-7. ANNUALIZED COSTS OF CHEVRON-BLADE MIST
ELIMINATORS AND SINGLE PACKED-BED SCRUBBERS FOR HARD
CHROMIUM PLATING MODEL PLANTS
(November 1988 Dollars)3
Model plant size
Chevron-blade
mist eliminators
Single set
of blades
Double set
of blades
Single
packed-bed
scrubber
Small*
Utilities0
Operator and maintenance labor
Maintenance materials
Packing replacement6
Indirect costs
Capital recovery
Annualized cost, $
Chromic acid recovery?
Net annualized costs, $
0
800
200
1,500
2.600
5,100
(300)
4,800
400
800
200
600
1,700
500
200
2,800
4.300
10,100
(300)
9,800
Utilities0
Operator and maintenance labor"
Maintenance materials
Packing replacement6
Indirect costs*
Capital recovery
Annualized cost, $
Chromic acid recovery^
Net annualized costs, $"
Lare&J
Utilities0
Operator and maintenance labor
Maintenance materials
Packing replacement6
Indirect costs*
Capital recovery
Annualized cost, $
Chromic acid recovery^
Net annualized costs, $
1,200
1,100
500
2,800
5.300
10.900
(2.400)
8,500
4,200
1,900
1,700
5,800
10.600
24,200
(9.100)
1-5,100
2,400
1,100
500
2,900
5.800
12,700
(2.500)
10,200
8,300
1,900
1,700
6,100
11.700
29,700
(9.600)
20,100
12,900
3,900
3,600
800
10,400
17.400
49,000
(10.000)
39,000
aAnnualized costs for mist eliminators are from Tables F-8 and F-9, and annualized costs for the single packed-bed scrubber
are from Table F-10 in Appendix F.
"Small model plant costs for each control device type are from Column Bj in Tables F-8 through F-10 in Appendix F.
^Utility costs for mist eliminators were rounded to zero if utility costs were less man or equal to $50 per year.
"Includes operator, supervisor, and maintenance labor.
ePacking replacement costs include the cost associated with purchasing new packing material and disposal of the old
material.
'Includes overhead, property tax, insurance, and administration.
^Chromic acid recovery credit for the mist eliminator with a single set of blades is based on a control efficiency of
95 percent. Chromic acid recovery credit for the mist eliminator with double sets of blades is based on a control efficiency
of 95 percent. Chromic acid recovery credit for the packed-bed scrubbers is based on a control efficiency of 99 percent.
Parentheses indicate negative values.
^Numbers may not add exactly due to independent rounding. Cost data were rounded to nearest $100.
iMedium model plant costs for each control device type are from Column Dj in Tables F-8 through F-10 in Appendix F.
JLarge model plant costs for each control device type are two times the annualized costs from Column DT in Tables F-8
through F-10 in Appendix F.
7-53
-------
TABLE 7-8. CAPITAL COSTS OF MESH-PAD MIST ELIMINATORS FOR
HARD CHROMIUM PLATING MODEL PLANTSa
(November 1988 Dollars)
Model plant size
Total purchased equipment (TPE)
Incremental ductwork cost6
Installation cost
Startup (1 percent of TPE)
Total capital cost, $
Smallb
13,900
0
9,000
100
23,000
Medium0
45,600
4,900
15,000
500
66,000
Larged
91,200
9,800
23,000
900
124,900
aCost data were rounded to the nearest $100.
^Small model plant costs are from column D of Table F-20 in
Appendix F.
GMedium model plant costs are equal to the sum of Columns A and B
plus two times Column C in Table F-20 in Appendix F.
^Large model plant costs are twice the costs of the medium model
plant.
eEstimated costs of additional ductwork required to modify
existing capture system to accommodate installation of mesh-pad
mist eliminator.
7-54
-------
TABLE 7-9.
ANNUALIZED COSTS FOR MESH-PAD MIST ELIMINATORS FOR
HARD CHROMIUM PLATING MODEL PLANTS3
(November 1988 Dollars)
Model plant size
Small
Medium
Large
Hard chromium plating
Utilities
Operator and maintenance
500
2,700
9,400
labor13
Maintenance materials
Mesh pad replacement0
Indirect costs^
Capital recovery6
Annualized cost, $
Chromic acid recovery^
Net annualized cost, $
1,000
400
900
1,700
3.800
8,300
(300)
8,000
2,400
2,600
2,600
5,600
10.800
26,700
(2.600)
24,100
5,300
8,900
5,100
13,500
20.400
62,600
(10.000)
52,600
f-Cost data are rounded to the nearest $100.
^Includes operator, supervisor, and maintenance labor.
GMesh pad replacement costs are based on a 4-year life for the
pad material. Includes cost of mesh pad replacement and
transportation and disposal costs of used pads.
dlncludes overhead, property tax, insurance, and administration.
eCapital recovery includes cost of capital for mesh-pad mist
eliminator unit(s) plus cost of capital for incremental
ductwork.
Chromic acid recovery credits are based on a removal efficiency
of 99 percent for mesh-pad mist eliminators used in hard
chromium plating processes. Parentheses indicate negative
values.
7-55
-------
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7-56
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7-57
-------
TABLE 7-11. CAPITAL COSTS OF SINGLE PACKED-BED SCRUBBERS
FOR DECORATIVE CHROMIUM ELECTROPLATING MODEL PLANTS
(November 1988 Dollars)a
Single
packed-bed
Model plant size scrubber
Small*3
Purchased equipment 19,500
Installation 17,000
Startup0 200
Total capital costd 36,700
Medium6
Purchased equipment 39,100
Installation 34,000
Startup0 400
Total capital costd 73,500
Large
Purchased equipment 70,200
Installation 53,700
Startup0 700
Total capital costd 124,600
aCapital costs for single packed-bed scrubbers are from Table F-6
in Appendix F.
bSmall model plant costs are presented in Column B in Table F-6
in Appendix F.
°Startup costs are based on 1 percent of the purchased equipment
cost.
dTotal capital cost is the sum of purchased equipment,
installation, and startup costs. Cost data were rounded to the
nearest $100.
eMedium model plant costs are two times small model plant costs.
^Large model plant costs are two times the control device costs
in Column C plus the control device costs in Column A from
Table F-6 in Appendix F.
7-58
-------
TABLE 7-12. ANNUALIZED COSTS OF SINGLE PACKED-BED SCRUBBERS
FOR DECORATIVE CHROMIUM ELECTROPLATING MODEL PLANTS3
(November 1988 Dollars)
Model plant size Single packed-bed scrubber
Smallb
Utilities
Operator and maintenance labor0
Maintenance materials
Packing replacement
Indirect costse
Capital recovery
Annualized cost, $
Chromic acid recovery*
Net annualized cost, $8 10,100
Medium
Utilities
Operator and maintenance laborc
Maintenance materials
Packing replacement
Indirect costs6
Capital recovery
Annualized cost, $
Chromic acid recovery
Net annualized cost, $8
Large1
Utilities
Operator and maintenance labor0
Maintenance materials
Packing replacement"
Indirect costs6
Capita] recovery
Annualized cost, $
Chromic acid recovery'
Net annualized cost, $8
aAnnualized costs for packed-bed scrubbers are from Table F-10 in Appendix F.
Small model plant costs are from Column Bj in Table F-10 in Appendix F.
clncludes operator, supervisor, and maintenance labor.
'racking replacement costs include the cost associated with purchasing new packing material and transportation and disposal
of the old material.
elncludes overhead, property tax, insurance, and administration.
'Chromic acid recovery credit for single blade chevron-blade mist eliminators is based on a control efficiency of 90 percent.
Chromic acid recovery credit for double blade chevron-blade mist eliminators is based on a control efficiency of
95 percent. Chromic acid recovery credit for packed-bed scrubbers is based on a control efficiency of 97 percent.
Parentheses indicate negative values. Costs were rounded to nearest $100.
^Numbers may not add exactly due to independent rounding. Costs were rounded to nearest $100.
.Medium model plant costs are two tunes the costs presented in Column 82 in Table F-10 in Appendix F.
'Large model plant costs are two times the costs in Column C plus the costs in Column A in Table F-10 in Appendix F.
7-59
-------
TABLE 7-13. CAPITAL COSTS OF MESH-PAD MIST ELIMINATORS FOR
DECORATIVE CHROMIUM ELECTROPLATING MODEL PLANTSa
(November 1988 Dollars)
Model plant size
Smallb Medium0 Larged
Total purchased equipment (TPE)
Incremental ductwork cost6
Installation cost
Startup (1 percent of TPE)
Total capital cost, $
13,900
0
9,000
100
23,000
27,900
0
11,000
300
39,200
62,700
6,800
17,000
700
87,200
aCost data were rounded to the nearest $100.
bSmall model plant costs are equal to the costs presented in
Column D of Table F-20 in Appendix F.
cMedium model plant costs are two times the costs presented in
Column D of Table F-20 in Appendix F.
^Large model plant costs are equal to five times the costs
presented in Column C in Table F-20 in Appendix F.
eEstimated cost of additional ductwork required to modify typical
capture system to accommodate installation to mesh-pad mist
eliminator
7-60
-------
TABLE 7-14. ANNUALIZED COSTS OF MESH-PAD MIST ELIMINATORS
FOR DECORATIVE CHROMIUM ELECTROPLATING MODEL PLANTSa
(November 1988 Dollars)
Utilities
Operator and maintenance labor*3
Maintenance materials
Mesh pad replacement0
Indirect costs^
Capital recovery6
Annualized cost, $
Chromic acid recovery^
Net annualized cost, $
Model
Small
500
1,000
400
900
1,700
3.800
8,300
0
8,300
plant size
Medium
2,100
1,700
1,500
1,900
3,500
6,400
17,100
(200) (
16,900
Large
7,800
3,800
5,600
3,800
9,100
14,200
44,300
1.500)
42,800
fCost data were rounded to the nearest $100.
^Includes operator, supervisor, and maintenance labor.
GMesh pad replacement costs are based on a 4-year life for
the pad material. Includes cost of mesh pad replacement and
transportation and disposal costs of used pads.
^Includes overhead, property tax, insurance, and
administration.
eCapital recovery includes cost of capital for mesh-pad mist
eliminator unit(s) plus cost of capital for incremental
ductwork.
^Chromic acid recovery credits are based on a removal
efficiency of 97 percent for mesh-pad mist eliminators used
in decorative chromium and chromic acid anodizing
operations.
7-61
-------
TABLE 7-15. ANNUALIZED COSTS OF TEMPORARY AND PERMANENT
FUME SUPPRESSANTS FOR DECORATIVE CHROMIUM
ELECTROPLATING MODEL PLANTS
(November 1988 Dollars)
Model plants
A. Model Tank Dataa
1 . Surface area of tank, fr
2. Temporary fume suppressants
a. Average makeup cost, $"
b. Average maintenance, cost, $/yrl
3. Permanent fume suppressants
a. Average makeup cost, $"
b. Average maintenance cost, $/yr)
4. Operating time basis, hr/yrc
B. Model Plant Data
1. No. of model tanks
2. Operating hours, hr/yrc
3. Temporary fume suppressants
a. Makeup cost, $° (A2a x Bl)
b. Maintenance cost, $yr" "
(A2b x B1)(B2/A4)
c. Annual cost, $/yre (B3a + B3b)
d. Chromic acid recovery, $/yre
e. Net annual cost, $/yr
4. Permanent fume suppressants
a. Makeup cost, $° (A3a x Bl)
b. Maintenance cost, S/yr3'^
(A3b x B1)(B2/A4)
c. Annual cost, $/yre (B4a + B4b)
d. Chromic acid recovery, $/yre'*
e. Net annual cost, S/yr6
Small
42
20
1,200
170
1,060
1,600
1
1,200
20
900
900
_Q
900
170
800
1,000
0
1,000
Medium
42
20
1,200
170
1,060
1,600
2
2,400
40
3,600
3,600
(200)
3,400
340
3,180
3,500
(200)
3,300
Large
72
40
3,280
460
4,360
4,800
5
3,600
200
12,300
12,500
(1.500)
11,000
2,300
16,350
18,700
(1.500)
17,200
aFume suppressant cost basis (original model tank parameters).
^Cost data were rounded to the nearest $10.
c Operating time of tanks = (operating time of plant, hr/yr) multiplied by (percent time electrodes are
energized).
^Maintenance cost-is adjusted by applying a ratio that corrects for the difference between the
operating time of the model tanks upon which the cost data are based and the revised operating time
of the model tanks.
eCost data were rounded to the nearest $10.
f Chromic acid recovery credits for fume suppressants are based on control efficiency of 99.5 percent.
Parentheses indicate negative values.
7-62
-------
TABLE 7-16. INCREMENTAL CAPITAL COST ASSOCIATED WITH INSTALLING
A TRIVALENT CHROMIUM PROCESS INSTEAD OF A HEXAVALENT CHROMIUM
PROCESS AT NEW DECORATIVE CHROMIUM ELECTROPLATING FACILITIES
(November 1988 Dollars)
Model plant size
Component
Small
Medium
Large
Startup (plating tank[s]) cost4'*
Initial passivation solution '°
Subtotal
Purchased equipment cost
2,800
500
3,300
5,500
1.000
6,500
27,500
6.500
34,000
Ampere-hour controller"
Anode boxes0'
Chillersd'6
Filterd'5
Subtotal
Taxes and freighte>25
TOTAL
Installation >
Indirect costsS'2
Total cost
Wastewater treatment cost savings^'
Net costk
1,600
7,800
9,300
7.600
26,300
2.100
28,400
4,300
8.800
44.800
-19.600*
25,200
3,200
15,600
18,600
15.200
52,600
4.200
56,800
8,500
17.600
89.400
-29.400)
60,000
8,000
39,000
71,000
54.500
172,500
13.800
186,300
27,900
57.800
306.000
-41.400)
264,600
aStartup cost for new plants would only consist of the incremental cost of the trivalent chromium bath
solution over the hexavalent chromium bath solution. The cost differential between the trivalent
chromium plating solution and the hexavalent plating solution is $1.60 per gallon of plating solution for
the small and medium model plants and $1.20 per gallon for the large model plant.
Passivation solution is required for some trivalent chromium processes.
cAnode boxes are required for all double-cell processes.
Optional equipment.
^axes and freight are estimated to be 3 and 5 percent, respectively, of the base equipment cost.
Installation costs are based on 15 percent of the purchased equipment costs.
^Indirect costs include costs associated with engineering and supervision (10 percent), process startup
(1 percent), and contingencies (20 percent) and are based on 31 percent of the purchased equipment
costs.
Represents the capital cost of a hexavalent chromium reduction unit for the wastewater volume
associated with each model plant.
^Batch process. .—
J Continuous process.
^The total capital cost is not solely attributable to air pollution control but also to process
improvement.
7-63
-------
TABLE 7-17. CAPITAL COST OF CONVERTING A HEXAVALENT CHROMIUM
PROCESS TO A TRIVALENT CHROMIUM PROCESS AT EXISTING
DECORATIVE CHROMIUM ELECTROPLATING FACILITIES
(November 1988 Dollars)
Component
Startup (tank conversion)3
Initial trivalent chromium
solution purchase
Initial passivation solution
purchase8
Waste disposal cost of hexavalent
chromium solution
Subtotal
Purchased equipment cost
o
Ampere-hour meter
Tank liner5
Replacement anodes and hangers
Anode boxes
Chillerb'8
Filter13'5
Subtotal
Taxes and freight0'25
TOTAL
Installation/modification '
Indirect*5'25
Total cost
Model
Small
10,900
500
3,700
15,100
1,600
2,200
3,300
7,800
9,300
7.600
31,800
2.500
34,300
6,900
10,600
66,900
plant size
Medium
21,800
1,000
7,400
30,200
3,200
4,400
6,600
15,600
18,600
15.200
63,600
5.100
68,700
13,700
21,300
133,900
Large
136,500
6,500
41.000
184,000
8,000
18,000
43,500
39,000
71,000
54.500
234,000
18.700
252,700
50,500
78,300
565,500
aStartup costs include the initial makeup of the trivalent chromium solution and the disposal cost of the
hexavalent chromium plating solution.
Optional equipment.
''Taxes and freight are estimated to be 3 and 5 percent, respectively, of the base equipment cost.
Installation/modification costs are based on 20 percent of purchased equipment costs.
Indirect costs include costs associated with engineering and supervision (10 percent), process startup
(1 percent), and contingencies (20 percent) and are estimated to be 31 percent of the purchased
equipment cost.
total capital cost is not solely attributable to air pollution control but also to process improvement.
7-64
-------
TABLE 7-18. SCENARIO 1: PLATING LINE COSTS FOR EACH MODEL PLANT
BASED ON THE ACTUAL HEXAVALENT CHROMIUM REWORK RATES
PRODUCTION FACTORS
A END-PRODUCT PARAMETERS
PART PLATED
PLATING TIME, MIN
CURRENT DENSITY, A/FT2
SURFACE AREA OF PART, FT2
PLATING THICKNESS, MILS
AMPERE-HOURS/FT2
AMPERE-HOURS/PART
B MODEL PLANT PARAMETERS
NO. OF PLATING LINES
OPERATING TIME, H/YR
% TIME ELECTRODES ARE ENERGIZED, %
FAN HORSEPOWER REQUIREMENT, HP
CHROMIUM WASTEWATER FLOW RATE, GPM/PLATING LINE
C. COST PARAMETERS
CR+6 WASTEWATER TREATMENT COSTS, 5/1000 GAL
CR+3 WASTEWATER TREATMENT COSTS, $/1000 GAL
CR+6 CHEMICAL COSTS, $/AH
CR+3 CHEMICAL COSTS, $/AH
FAN ELECTRICAlreOSTS, S/KWH
MODEL PLANT SIZE
SMALL
Ratchets
3.00
50.00
0.128
0.011
2.50
0.32
1
2000
60
10
6
0.75
0.34
0.00052
0.007
0.0461
MEDIUM
Faucets
3.55
125.00
0.540
0.00031
7.40
3.99
2
4000
60
20
6
0.75
0.34
0.00052
0.007
0.0461
LARGE
Bumpers
2.25
200.00
12.810
0.014
7.50
96.08
5
6000
60
35
12
0.75
0.34
0.00052
0.007
0.0461
7-65
-------
TABLE 7-18. (Continued)
PRODUCTION FACTORS
D. PRODUCTION PARAMETERS
1. REWORK RATES
a) Hexavalent Chromium Process, %
b) Trivalent Chromium Process, %
2. TRIVALENT CHROMIUM PRODUCTIVITY INCREASE, %
3. HEXAVALENT CHROMIUM MAXIMUM
PRODUCTION RATE, PARTS/YR
E. PRODUCTION RATES
1. HEXAVALENT CHROMIUM PROCESS
a. Maximum surface area per year, ft2/yr
b. Total # of parts produced, parts/yr
c. No. of once-through parts, parts/yr
d. No. of rework parts (parts processed twice), parts/yr
2. TRIVALENT CHROMIUM PROCESS
a. Maximum surface area per year, ft2/yr
b. Maximum # of parts plated per year, parts/yr
c. Total # of parts produced, parts/yr
d. No. of once-through parts, parts/yr
e. No. of rework parts (parts processed twice), parts/yr
F. CHEMICAL COST
HEXAVALENT CHROMIUM SOLUTION, $/FT2
HEXAVALENT CHROMIUM SOLUTION, J/PART
TRIVALENT CHROMIUM PROCESS, $/FT2
TRIVALENT CHROMIUM PROCESS, $/PART
MODEL PLANT SIZE
SMALL
1.000
1.0
20
5.20E+06
6.66E+05
5.15E+06
5. 10E-K)6
5.20E+04
7.99E+OS
6.24E+06
6.18E+06
6. 12E+06
6.24E+04
0.0013
0.0002
0.0175
0.0022
MEDIUM
3.000
1.0
20
4.04E+05
2.18E-K15
3.92E-HD5
3.80E-K15
1.21E+04
2.62E-K)5
4.85E+05
4.80E-K)5
4.75E-K)5
4.85E-K)3
0.0038
0.0021
0.0518
0.0280
LARGE
15.000
1.0
20
2.70EMD6
3.46E+07
2.30E+06
1.89E+06
4.05E+05
4.15E+07
3.24E+06
3.21E+06
3.18E+06
3.24E-H34
0.0039
0.0500
0.0525
0.6725
7-66
-------
TABLE 7-18. (Continued)
PRODUCTION FACTORS
G. ANNUAL PLATING COST
1 UNIT PLATING COSTS
a Hexavalent Chromium Process
1 (plating cost, S/part
2)plating cost, $/ft2
3 (rework plating cost, $/part
b Trivalent Chromium Process
Dplating cost, $/part
2)plating cost, $/ft2
3)rework plating cost, $/part
2. ANNUAL PLATING COSTS
a. Hexavalent Chromium Process
l)plating costs — once-through parts, $/yr
2)plating costs — rework, $/yr
3 (annual plating costs, $/yr
b. Tnvalent Chromium Process
Opiating costs — once-through parts, $/yr
2)plating costs — rework, $/yr
3 (annual plating costs, $/yr
H. WASTEWATER TREATMENT COSTS
1. HEXAVALENT CHROMIUM PROCESS
a) Wastewater volumes, gal/yr
b) Treatment costs, $/yr
2. TRIVALENT CHROMIUM PROCESS
a) Wastewater volumes, gal/yr
b) Treatment costs, $/yr
MODEL PLANT SIZE :
SMALL
$0.100
$0.780
0.200
$0.102
0.796
0.204
$508,581
$10,379
$518,960
$623,139
$12,717
$635,856
720,000
$540
720,000
$240
MEDIUM
$0.421
$0.780
0.842
$0.447
0.828
0.894
$160,085
$10,218
$170,303
$212,592
$4,339
$216,931
2,880,000
$2,160
2,880,000
$970
LARGE
$9.992
$0.780
19.984
$10.614
0.829
21.229
$18,884,502
$8,093,358
$26,977,860
$33,702,843
$687,813
$34,390,656
21,600,000
$16,200
21,600,000
$7,290
7-67
-------
TABLE 7-18. (Continued)
PRODUCTION FACTORS
1. FAN ELECTRICAL COSTS
HEXAVALENT CHROMIUM PROCESS
a) Fan electrical usage, kWh/yr
b) Fan electrical costs, $/yr
J. PLATING LINE COSTS
1. HEXAVALENT CHROMIUM PROCESS
a)annual plating costs, $/yr
b)wastewater treatment costs, $/yr
c)fan electrical costs, $/yr
d)total plating line costs, $/yr
e)total plating line costs, $/part
2. TRIVALENT CHROMIUM PROCESS
a)annual plating costs, $/yr
b)wastewater treatment costs, $/yr
c)total plating line cost, $/yr
d)total plating line costs, $/part
COST DIFFERENTIAL BETWEEN THE PROCESSES, S/PART (a)
COST DIFFERENTIAL BETWEEN THE PROCESSES, $/FT2 (b)
ANNUAL COST DIFFERENTIAL, $/YR (c)
MODEL PLANT SIZE
SMALL
14,920
$688
$518,960
$540
$688
$520,188
0.1010
$635,856
$240
$636,096
0.1030
-0.0020
-0.0156
($10,300)
MEDIUM
59,680
$2,751
$170,303
$2,160
$2,751
$175,214
0.4467
$216,931
$970
$217,901
0.4536
-0.0070
-0.0130
($2,700)
LARGE
156,660
$7,222
$26,977,860
$16,200
$7,222
$27,001,282
11.7653
$34,390,656
$7,290
$34,397,946
10.7239
1.0410
0.0813
$2,389,100
(a) Obtained from G.l.e minus G.2.d. Numbers were independently rounded.
(b) Obtained by dividing the $/part value by the surface area of the part.
(c) Based on hexavalent chromium production rate*.
7-68
-------
TABLE 7-19. SCENARIO 2: PLATING LINE COSTS FOR EACH MODEL PLANT
BASED ON THE AVERAGE HEXAVALENT CHROMIUM REWORK RATES
PRODUCTION FACTORS
A. END-PRODUCT PARAMETERS
PART PLATED
PLATING TIME, MIN
CURRENT DENSITY, A/FT2
SURFACE AREA OF PART, FT2
PLATING THICKNESS, MILS
AMPERE-HOURS/FT2
AMPERE-HOURS/PART
B. MODEL PLANT PARAMETERS
NO. OF PLATING LINES
OPERATING TIME, H/YR
% TIME ELECTRODES ARE ENERGIZED, %
FAN HORSEPOWER REQUIREMENT, HP
CHROMIUM WASTEWATER FLOW RATE, GPM/PLATING LINE
C. COST PARAMETERS
CR-t-6 WASTEWATER TREATMENT COSTS, S/1000 GAL
CR+3 WASTEWATER TREATMENT COSTS, J/1000 GAL
CR+6 CHEMICAL COSTS, $/AH
CR+3 CHEMICAL COSTS, $/AH
FAN ELECTRICAL COSTS, $/KWH
MODEL PLANT SIZE j
SMALL
Ratchets
3.00
50.00
0.128
0.011
2.50
0.32
1
2000
60
10
6
0.75
0.34
0.00052
0.007
0.0461
MEDIUM
Faucets
3.55
125.00
0.540
0.00031
7.40
3.99
2
4000
60
20
6
0.75
0.34
0.00052
0.007
0.0461
LARGE
Bumpers
2.25
200.00
12.810
0.014
7.50
96.08
5
6000
60
35
12
0.75
0.34
0.00052
0.007
0.0461
7-69
-------
TABLE 7-19. (Continued)
PRODUCTION FACTORS
D. PRODUCTION PARAMETERS
1. REWORK RATES
a) Hexavalent Chromium Process, %
b) Trivalent Chromium Process, %
2. TRIVALENT CHROMIUM PRODUCTIVITY INCREASE, %
3. HEXAVALENT CHROMIUM MAXIMUM
PRODUCTION RATE, PARTS/YR
E. PRODUCTION RATES
1. HEXAVALENT CHROMIUM PROCESS
a. Maximum surface area per year, ft2/yr
b. Total # of parts produced, parts/yr
c. No. of once-through parts, parts/yr
d. No. of rework parts (parts processed twice), parts/yr
2. TRIVALENT CHROMIUM PROCESS
a. Maximum surface area per year, ft2/yr
b. Maximum tf of parts plated per year, parts/yr
c. Total M of parts produced, parts/yr
d No. of once-through parts, parts/yr
e. No. of rework parts (parts processed twice), parts/yr
F. CHEMICAL COST
HEXAVALENT CHROMIUM SOLUTION, S/FT2
HEXAVALENT CHROMIUM SOLUTION, S/PART
TRIVALENT CHROMIUM PROCESS, $/FT2
TRIVALENT CHROMIUM PROCESS, J/PART
MODEL PLANT SIZE
SMALL
7.000
1.0
20
5.20E+06
6.66E+05
4.84E+06
4.47E+06
3.64E+05
7.99E-K35
6.24E+06
6.18E+06
6.12E+06
6.24E+04
0.0013
0.0002
0.0175
0.0022
MEDIUM
7.000
1.0
20
4.04E+05
2.18E+05
3.76E+05
3.48E+05
2.83E+04
2.62E+05
4.85E+05
4.80E+05
4.75E+05
4.85E-M)3
0.0038
0.0021
0.0518
0.0280
LARGE
7.000
1.0
20
2.70E+06
3.46E+07
2.51E-K)6
2.32E+06
1.89E+05
4.15E+07
3.24E+06
3.21E+06
3A&E+O6
3.24E-KJ4
0.0039
0.0500
0.0525
0.6725
7-70
-------
TABLE 7-19. (Continued)
PRODUCTION FACTORS
G. ANNUAL PLATING COST
1. UNIT PLATING COSTS
a. Hexavalent Chromium Process
l)plating cost, $/part
2)plating cost, $/ft2
3)rework plating cost, $/part
b. Trivalent Chromium Process
l)plating cost, $/part
2)plating cost, $/ft2
3)rework plating cost, $/part
2. ANNUAL PLATING COSTS
a. Hexavalent Chromium Process
l)plating costs — once-through parts, $/yr
2)plating costs — rework, $/yr
3)annuaJ plating costs, $/yr
b. Trivalent Chromium Process
l)plating costs — once-through parts, $/yr
2)plating costs — rework, $/yr
3)annual plating costs, $/yr
H. WASTEWATER TREATMENT COSTS
1. HEXAVALENT CHROMIUM PROCESS
a) Wastewater volumes, gal/yr
b) Treatment costs, $/yr
2. TRIVALENT CHROMIUM PROCESS
a) Wastewater volumes, gal/yr
b) Treatment costs, $/yr
MODEL PLANT SIZE
SMALL
$0.100
$0.780
0.200
$0.102
0.796
0.204
$446,306
$72,654
$518,960
$623,139
$12,717
$635,856
720,000
$540
720,000
$240
' MEDIUM
$0.421
$0.780
0.842
$0.447
0.828
0.894
$146,461
$23,842
$170,303
$212,592
$4,339
$216,931
2,880,000
$2,160
2,880,000
$970
LARGE
$9.992
$0.780
19.984
$10.614
0.829
21.229
$23,200,960
$3,776,900
$26,977,860
$33,702,843
$687,813
$34,390,656
21,600,000
$16,200
21,600,000
$7,290
7-71
-------
TABLE 7-19. (Continued)
PRODUCTION FACTORS
I. FAN ELECTRICAL COSTS
HEXAVALENT CHROMIUM PROCESS
a) Fan electrical usage, kWh/yr
b) Fan electrical costs, $/yr
J. PLATING LINE COSTS
1. HEXAVALENT CHROMIUM PROCESS
a)annual plating costs, $/yr
b)wastewater treatment costs, $/yr
c)fan electrical costs, $/yr
d)total plating line costs, $/yr
e)total plating line costs, $/part
2. TRIVALENT CHROMIUM PROCESS
a)annual plating costs, $/yr
b)wastewater treatment costs, $/yr
c)total plating line cost, $/yr
d)total plating line costs, $/part
COST DIFFERENTIAL BETWEEN THE PROCESSES, S/PART (a)
COST DIFFERENTIAL BETWEEN THE PROCESSES, $/FT2 (b)
ANNUAL COST DIFFERENTIAL, $/YR (c)
MODEL PLANT SIZE
SMALL
14,920
$688
$518,960
$540
$688
$520,188
0.1076
$635,856
$240
$636,096
0.1030
0.0050
0.0391
$24,200
MEDIUM
59,680
$2,751
$170,303
$2,160
$2,751
$175,214
0.4660
$216,931
$970
$217,901
0.4536
0.0120
0.0222
$4,500
LARGE
156,660
$7,222
$26,977,860
$16,200
$7,222
$27,001,282
10.7532
$34,390,656
$7,290
$34,397,946
10.7239
0.0290
0.0023
$72,800
(a) Obtained from G.l.e minus G.2.d. Numbers were independently rounded.
(b) Obtained by dividing the $/part value by the surface area of the part.
(c) Based on hexavalent chromium production rates.
7-72
-------
TABLE 7-20. SCENARIO 3: PLATING LINE COSTS FOR EACH MODEL PLANT
BASED ON THE BREAK-EVEN HEXAVALENT CHROMIUM REWORK RATES
PRODUCTION FACTORS
A END-PRODUCT PARAMETERS
PART PLATED
PLATING TIME, MJN
CURRENT DENSITY, A/FT2
SURFACE AREA OF PART, FT2
PLATING THICKNESS, MILS
AMPERE-HOURS/FT2
AMPERE-HOURS/PART
B MODEL PLANT PARAMETERS
NO. OF PLATING LINES
OPERATING TIME, H/YR
% TIME ELECTRODES ARE ENERGIZED, %
FAN HORSEPOWER REQUIREMENT, HP
CHROMIUM WASTEWATER FLOW RATE, GPM/PLATING LINE
C. COST PARAMETERS
CR+6 WASTEWATER TREATMENT COSTS, S/1000 GAL
CR+3 WASTEWATER TREATMENT COSTS, S/1000 GAL
CR+6 CHEMICAL COSTS, $/AH
CR+3 CHEMICAL COSTS, $/AH
FAN ELECTRICAL COSTS, J/KWH
MODEL PLANT SIZE ;
SMALL
Ratchets
3.00
50.00
0.128
0.011
2.50
0.32
1
2000
60
10
6
0.75
0.34
0.00052
0.007
0.0461
MEDIUM
Faucets
3.55
125.00
0.540
0.00031
7.40
3.99
2
4000
60
20
6
0.75
0.34
0.00052
0.007
0.0461
LARGE
Bumpers
2.25
200.00
12.810
0.014
7.50
96.08
5
6000
60
35
12
0.75
0.34
0.00052
0.007
0.0461
7-73
-------
TABLE 7-20. (Continued)
PRODUCTION FACTORS
D. PRODUCTION PARAMETERS
1. REWORK RATES
a) Hexavalent Chromium Process, %
b) Trivalent Chromium Process, %
2. TRIVALENT CHROMIUM PRODUCTIVITY INCREASE, %
3. HEXAVALENT CHROMIUM MAXIMUM
PRODUCTION RATE, PARTS/YR
E. PRODUCTION RATES
1. HEXAVALENT CHROMIUM PROCESS
a. Maximum surface area per year, ft2/yr
b. Total # of parts produced, parts/yr
c. No. of once-through parts, parts/yr
d. No. of rework parts (parts processed twice), parts/yr
2. TRIVALENT CHROMIUM PROCESS
a. Maximum surface area per year, ft2/yr
b. Maximum # of parts plated per year, parts/yr
c. Total n of parts produced, parts/yr
d. No. of once-through parts, parts/yr
e. No. of rework parts (parts processed twice), parts/yr
F. CHEMICAL COST
HEXAVALENT CHROMIUM SOLUTION, $/FT2
HEXAVALENT CHROMIUM SOLUTION, $/PART
TRIVALENT CHROMIUM PROCESS, $/FT2
TRIVALENT CHROMIUM PROCESS, S/PART
MODEL PLANT SIZE
SMALL
2.850
1.0
20
5.20E+06
6.66E+05
5.05E+06
4.90E+06
1.48E+05
7.99E+05
6.24E+06
6.18E+06
6.12E+06
6.24E+04
0.0013
0.0002
0.0175
0.0022
MEDIUM
4.500
1.0
20
4.04E+05
2.18E+05
3.86E+05
3.68E+05
1.82E+04
2.62E+05
4.85E+05
4.80E+05
4.75E+05
4.85E+03
0.0038
0.0021
0.0518
0.0280
LARGE
6.750
1.0
20
2.70E+06
3.46E+07
2.52E+06
2.34E+06
1.82E+05
4.15E+07
3.24E+06
3.21E+06
3.18E+06
3.24E+04
0.0039
00500
00525
06725
7-74
-------
TABLE 7-20. (Continued)
PRODUCTION FACTORS
G. ANNUAL PLATING COST
1. UNIT PLATING COSTS
a. Hexavalent Chromium Process
l)plating cost, $/part
2)plating cost, $/ft2
3)rework plating cost, $/part
b. Trivalent Chromium Process
l)plating cost, $/part
2)plating cost, $/ft2
3)rework plating cost, $/part
2. ANNUAL PLATING COSTS
a. Hexavalent Chromium Process
l)plating costs — once-through parts, $/yr
2)plating costs — rework, $/yr
3)annual plating costs, $/yr
b. Trivalent Chromium Process
l)plating costs — once-through parts, $/yr
2)plating costs — rework, $/yr
3)annual plating costs, J/yr
H. WASTE WATER TREATMENT COSTS
1. HEX AVALENT CHROMIUM PROCESS
a) Wastewater volumes, gal/yr
b) Treatment costs, J/yr
2. TRIVALENT CHROMIUM PROCESS
a) Wastewater volumes, gal/yr
b) Treatment costs, $/yr
MODEL PLANT SIZE
SMALL
$0.100
$0.780
0.200
$0.102
0.796
0.204
$489,379
$29,581
$518,960
$623,139
$12,717
$635,856
720,000
$540
720,000
$240
MEDIUM
$0.421
$0.780
0.842
$0.447
0.828
0.894
$154,976
$15,327
$170,303
$212,592
$4,339
$216,931
2,880,000
$2,160
2,880,000
$970
LARGE
$9.992
$0.780
19.984
$10.614
0.829
21.229
$23,335,849
$3,642,011
$26,977,860
$33,702,843
$687,813
$34,390,656
21,600,000
$16,200
21,600,000
$7,290
I
7-75
-------
TABLE 7-20. (Continued)
PRODUCTION FACTORS
I. FAN ELECTRICAL COSTS
HEXAVALENT CHROMIUM PROCESS
a) Fan electrical usage, kWh/yr
b) Fan electrical costs, $/yr
J. PLATING LINE COSTS
1. HEXAVALENT CHROMIUM PROCESS
a)annual plating costs, J/yr
b)wastewater treatment costs, $/yr
c)fan electrical costs, $/yr
d) total plating line costs, $/yr
e)total plating line costs, $/part
2. TRIVALENT CHROMIUM PROCESS
a)annual plating costs, $/yr
b)wastewater treatment costs, $/yr
c)total plating line cost, $/yr
d)total plating line costs, $/part
COST DIFFERENTIAL BETWEEN THE PROCESSES, $/PART (a)
COST DIFFERENTIAL BETWEEN THE PROCESSES, $/FT2 (b)
ANNUAL COST DIFFERENTIAL, $/YR (c)
MODEL PLANT SIZE
SMALL
14,920
$688
$518,960
$540
$688
$520,188
0.1030
$635,856
$240
$636,096
0.1030
0.0000
0.0000
$0
MEDIUM
59,680
$2,751
$170,303
$2,160
$2,751
$175,214
0.4538
$216,931
$970
$217,901
0.4536
0.0000
0.0000
$0
LARGE
156,660
$7,222
$26,977,860
$16,200
$7,222
$27,001,282
10.7244
$34,390,656
$7,290
$34,397,946
10.7239
0.0000
0.0000
SO
(a) Obtained from G. 1 .e minus G.2.d. Numbers were independently rounded.
(b) Obtained by dividing the $/part value by the surface area of the part.
(c) Based on hexavalent chromium production rates.
7-76
-------
TABLE 7-21. CAPITAL RECOVERY COSTS FOR EACH MODEL PLANT
REPRESENTATIVE OF BOTH NEW AND EXISTING FACILITIES
Model plant size
Capital recovery costs, $/yr Small Medium Large
Existing facility 13,200 26,300 108,900
New facility 6,000 3,400 54,000
7-77
-------
TABLE 7-22. MODEL PLANT INCREMENTAL ANNUALIZED COSTS
ASSOCIATED WITH THE USE OF THE TRIVALENT CHROMIUM PROCESS
Annual ized cost components
Capital recovery values, $/yr
1 . Existing facility
2. New facility
Process cost differential, $/yr
1. Scenario 1
2. Scenario 2C
3. Scenario 3"
Model plant size:
Small:
ratchets
13,200
6,000
10,300
(24,200)
0
end-product3
Medium:
faucets
26,300
13,400
2,700
(4,500)
0
Large:
bumpers
108,900
54,000
(2,389,100)
(72,800)
0
Incremental annual ized costs. $/yr
1. Scenario 1
2.
3.
a. Existing facility
b. New facility
Scenario 2
a. Existing facility
b. New facility
Scenario 3
a. Existing facility
b. New facility
23,500
16,300
(11,000)
(18,200)
13,200
6,000
29,000
16,100
21,800
8,900
26,300
13,400
(2,280,200)
(2,335,100)
36,100
(18,800)
108,900
54,000
Parentheses indicate a cost savings.
^lexavalent chromium reject rate was set at the value given by the plants that produce the end
product selected.
cftexavalent chromium reject rate was set at the average of the values given by the plants.
^exavalent chromium reject rate was set so that a process cost differential of zero was obtained.
7-78
-------
TABLE 7-23. CHROMIC ACID ANODIZING MODEL PLANT
PARAMETERS AND BASELINE CONDITIONS
Model plant size
Small
Large
Model plant parameters
Operating time, hr/yr
Percent of operating time electrodes are energized
Time electrodes are energized, hr/yr
Uncontrolled emission factor, kg/hr/m2 (Ib/hr/ft2)8
Uncontrolled emission rate per plant, kg/yr (Ib/yr)"
No. of tanks
Tank dimensions (1, w, d), m (ft)
Total surface area of tanks, a? (ft2)
Total tank capacity, L (gal)'i
Ventilation rate per tank, nr/nrin (fr/min)
Packed-bed scrubbers
No. of control devices
Inlet gas flow rate per control device, m^/min (ft^/min)
Mesh-pad mist eliminator
No. of control devices
Inlet gas flow rate per control device, nr/min (ft^/min)
Baseline conditions"
No. of operations nationwide:
Level of control, percent:
Uncontrolled
Mist eliminator6
Chemical fume suppressant
Packed-bed scrubber^
Total
No. of operations nationwide:
Uncontrolled
Mist eliminator6
Chemical fume suppressant
Packed-bed scrubber^
Total
2,000
70
1,400
6xlCY
(1.23 x 10"4)
3.3 (7.2)
1
3.6, 1.1, 1.8
(12.0, 3.5, 6.0)
3.9 (42)
6,500 (1,730)
297 (10,500)
1
340 (12,000)
1
340 (12,000)
515
40
10
30
_20
100
206
51
103
155
515
6,000
40
2,400
6X10-4
(1.23 x lO^4)
40 (88)
9.1, 1.5,2.7
(30.0, 5.0, 9.0)
28(300)
72,190 (19,070)
2 @ 531 (18,750)
1
1,130 (40,000)
4 @ 283 (10,000)
165
40
10
30
M
100
66
16
33
-5Q
165
aKg/hr/m2 Qb/hr/ft2) of tank surface are*.
Uncontrolled emission rate = (total tank surface area) (emission factor) (time electrodes are energized).
cAssumed 15.2 cm (6.0 in.) of freeboard space between surface of tank and surface of plating solution.
See Appendix F for derivation of number of operations nationwide and baseline level of control.
eChevron-blade mist eliminator with a single set of blades with control efficiency of 90 percent.
Fume suppressant with control efficiency of 97 percent.
^Packed-bed scrubber with control efficiency of 95 percent.
7-79
-------
TABLE 7-24. CAPITAL COSTS OF CHEVRON-BLADE MIST
ELIMINATORS AND SINGLE PACKED-BED SCRUBBERS
FOR CHROMIC ACID ANODIZING MODEL PLANTS3
(November 1988 Dollars)
Model plant size
Chevron-blade
mist eliminators
with a single
set of blades
Single packed-bed
scrubber
Small0
Purchased equipment
Installation
Startup0
Total capital costd
Large6
Purchased equipment
Installation
Startup0
Total capital costd
10,100
12,300
100
22,500
27,700
20,600
300
48,600
19,500
17,000
200
36,700
52,100
26,100
500
78,700
aCapital costs for mist eliminators are from Table F-4 in
Appendix F, and capital costs for scrubbers are from Table F-6
in Appendix F.
DSmall model plant costs for each control device type are from
Column B in Tables F-4 and F-6 in Appendix F.
GStartup costs are 1 percent of the purchased equipment cost.
dTotal capital cost is the sum of the purchased equipment,
installation, and startup costs. Cost data were rounded to
nearest $100.
6Large model plant costs for each control device type are
from Column E in Tables F-4 and F-6 in Appendix F.
7-80
-------
TABLE 7-25. ANNUALIZED COSTS OF CHEVRON-BLADE
MIST ELIMINATORS AND SINGLE PACKED-BED SCRUBBERS
FOR CHROMIC ACID ANODIZING MODEL PLANTS3
(November 1988 Dollars)
Model plant size
Chevron-blade mist
eliminator with a single
set of blades
Single
packed-bed
scrubber
Small"
Utilities
Operator and maintenance labor0
Maintenance materials
Packing replacement"
Indirect costs6
Capital recovery
Annualized cost, $
Chromic acid recovery
Net annualized cost, $8
5,100
10,100
Large
Utilities
Operator and maintenance labor0
Maintenance materials
Packing replacement"
Indirect costs6
Capital recovery
Annualized cost, $
Chromic acid recovery
Net annualized cost, $8
0
1,400
800
—
3,300
5.700
11,200
(200)
11,000
5,000
3,100
1,900
400
6,200
9.200
25,800
(300)
25,500
aAnnualized costs for mist eliminators are from Table F-8 in Appendix F and capital costs for scrubbers are
from Table F-10 in Appendix F.
^Small model plant costs for each control device type are from Column Bj presented in Tables F-8 and F-10 in
Appendix F.
clncludes operator, supervisor, and maintenance labor.
^Packing replacement costs include the cost associated with purchasing new packing material and transportation
and disposal of old material.
Includes overhead, property tax, insurance, and administration.
Chromic acid recovery credit for chevron-blade mist eliminators is based on a control efficiency of 90 percent.
Chromic acid recovery credit for packed-bed scrubbers is based on a control efficiency of 97 percent.
Parentheses Indicate negative values. Costs were rounded to nearest $100.
Clumbers may not add exactly due to independent rounding. Cost data were rounded to nearest $100.
\arge model plant costs for each control device type are from Column E in Tables F-8 and F-10 in
Appendix F.
7-81
-------
TABLE 7-26. CAPITAL COSTS OF MESH-PAD MIST ELIMINATORS FOR
CHROMIC ACID ANODIZING MODEL PLANTS3
(November 1988 Dollars)
Model plant size
Total purchased equipment (TPE)
Incremental ductwork cost°
Installation cost
Startup (1 percent of TPE)
Total capital cost, $
Smallb
13,900
0
9,000
100
23,000
Largec
50,100
26,100
15,000
500
91,700
aAnnualized cost data were rounded to the nearest $100.
bSmall model plant costs are equal to the costs presented in
Column D of Table F-20 in Appendix F.
cLarge model plant costs are equal to four times the costs
presented in Column C in Table F-20 in Appendix F.
Estimated cost of additional ductwork required to modify a
typical capture system to accommodate installation of a
mesh-pad mist eliminator.
7-82
-------
TABLE 7-27. ANNUALIZED COSTS OF MESH-PAD MIST ELIMINATORS
FOR CHROMIC ACID ANODIZING MODEL PLANTSa
(November 1988 Dollars)
Model plant size
Small Large
Utilities
Operator and maintenance labor*3
Maintenance materials
Mesh-pad replacement0
Indirect costs^
Capital recovery6
Annualized cost, $
Chromic acid recovery^
Net annualized cost, $
500
1,000
400
900
1,700
3.800
8,300
0
8,300
6,200
3,200
4,400
3,000
8,300
15.000
40,100
(300)
39,800
fCost data were rounded to the nearest $100.
^Includes operator, supervisor, and maintenance labor.
cMesh pad replacement costs are based on a 4-year life for the
pad material. Includes costs of mesh pad replacement and
transportation and disposal costs of used pads.
"Includes overhead, property tax, insurance, and administration.
eCapital recovery includes cost of capital for mesh-pad mist
eliminator unit(s) plus cost of capital for incremental
ductwork.
"chromic acid recovery credits are based on a removal efficiency
of 97 percent for mesh-pad mist eliminators used in chromic acid
anodizing operations.
7-83
-------
TABLE 7-28. ANNUALIZED COSTS OF PERMANENT FUME SUPPRESSANTS
FOR CHROMIC ACID ANODIZING MODEL PLANTSa
(November 1988 Dollars)
Model plant size
Small
Large
A. Model Tank Data*3
1.
2.
3.
4.
Surface area of model tanks, ft2
Average makeup cost, $
Average maintenance cost, $/yr
Operating time basis, hr/yrc
42
110
520
500
150
620
4,050
5,760
B. Model Plant Data
l.
2.
3.
4.
_5.
6.
7.
8.
No. of model tanks
Surface area of model tanks, ft2
Operating hours, hr/yrc
Makeup cost, $ (A2 x Bl)
Maintenance cost, $/yc
(A3 x Bl) (B3/A4)
Annual cost, $/yre (B4 + B5)
Chromic acid recovery, $/yre '
Net annual cost, $/yre
1
42
1,400
110
1.460
1,600
0
1,600
2
150
2,400
1,240
3.380
4,600
(300)
4, 300
aCost data were rounded to the nearest $10.
^Fume suppressant cost basis (original model tank parameters).
C0perating time of tanks = (operating time of plant, hr/yr)
multiplied by (percent time electrodes energized).
Maintenance cost is adjusted by applying a ratio that corrects
for the difference between the operating time of the model tanks
upon which the cost data are based and the revised operating
time of the model tanks.
eCost data were rounded to nearest $100.
^Chromic acid recovery credits for fume suppressants are based on
a control efficiency of 99.5 percent. Parentheses indicate
negative values.
7-84
-------
TABLE 7-29. NATIONWIDE CAPITAL AND ANNUALIZED COSTS FOR EACH
CONTROL OPTION FOR HARD CHROMIUM PLATING OPERATIONS
(Millions of Dollars)3 "
Control option
Small Medium Large
plants plants plants
Total
Option Ic
Capital cost
Annualized cost
Chromic acid recovery credit1^
Net annualized cost
23.14 13.42
6.02 3.65
(0.23) (0.55)
5.79 3.11
13.00 49.57
4.03 13.70
(1.00) (1.78)
3.03 11.93
Option IIe
Capital cost
Annualized cost
Chromic acid recovery creditc
Net annualized cost
33.22 19.64
8.41 5.19
(0.32) (0.79)
8.09 4.40
19.01 71.86
5.79 19.39
(1.45) (2.56)
4.34 16.83
Option IIIaf
Capital cost
Annualized cost
Chromic acid recovery creditc
Net annualized cost
42.62 24.73
11.36 6.87
(0.32) (0.81)
11.04 6.07
23.93 91.28
7.61 25.85
(1.50) (2.63)
6.11 23.22
Option
Capital cost
Annualized cost
Chromic acid recovery creditc
Net annualized cost
32.67 23.01
10.13 7.91
(0.32) (0.81)
9.81 7.10
21.56 77.24
8.86 26.90
(1.50) (2.63)
7.36 24.27
^November 1988 dollars.
Numbers may not add exactly due to independent rounding.
C0ption I is the baseline, or no-action, alternative that is
based on the existing level of control.
^Parentheses indicate negative values.
eOption II represents 95 percent level of control and is
based on the use of chevron-blade mist eliminators with
double sets of blades.
^Option Ilia represents 99 percent level of control and is
based on the use of single packed-bed scrubbers.
^Option Illb represents 99 percent level of control and is
based on the use of mesh-pad mist eliminators.
7-85
-------
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7-86
-------
TABLE 7-31. NATIONWIDE CAPITAL AND ANNUALIZED COSTS FOR EACH
CONTROL OPTION FOR DECORATIVE CHROMIUM
ELECTROPLATING OPERATIONS a b
(Millions of Dollars)
Control option
Option Ic
Capital cost
Annualized cost
Chromic acid recovery credit"
Net annualized cosr5
Option Hae
Capital cost
Annualized cost
Chromic acid recovery credit"
Net annualized cost
OptionIIbf
Capital cost
Annualized cost
Chromic acid recovery credit
Net annualized cost"
Option HIS
Capital cost
Annualized cost
Chromic acid recovery credit
Net annualized cost
Option IVh
Capital cost
Annualized cost1
Annualized cost)
Annualized cost*
Small
plants
36.99
11.97
0.00
11.97
49.32
15.37
0.00
15.37
44.72
14.76
0.00
14.76
34.94
11.86
0.00
11.86
149.86
52.64
(24.64)
29.57
Medium
plants
13.89
5.30
(0.07)
5.23
18.52
6.67
(0.08)
6.59
16.36
6.37
(0.08)
6.29
13.08
5.35
(0.08)
5.26
56.24
12.18
9.16
11.05
Large
plants
7.85
4.73
(0.18)
4.56
10.47
5.61
(0.21)
5.40
9.68
5.66
(0.21)
5.45
7.35
5.08
(0.21)
4.87
79.17
(319.23)
5.05
15.25
Total
58.73
22.00
(0.25)
21.76
78.31
27.65
(0.29)
27.36
70.76
26.80
(0.29)
26.51
55.37
22.28
(0.29)
21.99
285.26
(254.41)
(10.43)
55.86
aNovember 1988 dollars.
"Numbers may not add exactly due to independent rounding.
cOption I is the baseline, or no-action, option that is based on the existing level of control.
^Parentheses indicate negative values.
eOption Ha represents 97 percent level of control and is based on the use of single packed-bed scrubbers.
Option lib represents 97 percent level of control and is based on the use of mesh-pad mist eliminators.
^Option HI represents 99.5 percent level of control and is based on the use of chemical fume
suppressants.
"Option IV represents 100 percent level of control and is based on the use of trivalent chromium plating
process.
'Annualized costs are based on Scenario 1 for the trivalent chromium process. This scenario assumes
reject rates of 1, 3, and 15 percent, respectively, for each model plant.
JAnnualized costs are based on Scenario 2 for the trivalent chromium process. This scenario assumes a reject
rate of 7 percent for each model plant.
''Annualized costs are based on Scenario 3 for the trivalent chromium process. This scenario assumes reject
rates of 2.85, 4.5, and 6.75, respectively, for each model plant.
7-87
-------
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7-90
-------
TABLE 7-33. NATIONWIDE CAPITAL AND ANNUALIZED COSTS FOR EACH
CONTROL OPTION FOR CHROMIC ACID ANODIZING OPERATIONS
(Millions of Dollars)3 b
Control options
Option Ic
Capital cost
Annual ized cost
Chromic acid recovery credit^
Net annual ized cost''
Option IIae
Capital cost
Annual ized cost
Chromic acid recovery credit
Net annual ized cost'3
Option IIbf
Capital cost
Annual ized cost
Chromic acid recovery credit"
Net annual ized cost'3
Option HIS
Capital cost
Annual ized cost
Chromic acid recovery credit^
Net annualized cost"
Small plants
4.93
1.55
0.00
1.55
13.68
3.96
0.00
3.96
9.99
3.48
0.00
3.48
0.00
0.82
0.00
0.82
Large plants
3.37
1.26
(0.02)
. 1.24
9.37
3.25
(0.05)
3.20
10.49
4.44
(0.05)
4.39
0.00
0.76
(0.05)
0.71
Total
8.30
2.81
(0.02)
2.78
23.05
7.20
(0.05)
7.15
20.48
7.93
ffl.05)
7.88
0.00
1.58
(0.05.)
1.53
November 1988 dollars.
lumbers may not add exactly due to independent rounding.
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7-92
-------
TABLE 7-35. ANNUALIZED HAZARDOUS WASTE TRANSPORTATION AND
DISPOSAL COSTS ATTRIBUTABLE TO THE CONTROL OPTIONS BASED ON
THE USE OF SINGLE PACKED-BED SCRUBBERS OR MESH-PAD MIST
ELIMINATORS FOR HARD CHROMIUM PLATING OPERATIONS3
(November 1988 Dollars)
Packed-bed scrubbers6
Plant size
Option I
Small
Medium
Large
Total
Option n
Small
Medium
Large
Total
Option IHa
Small
Medium
Large
Total
Option fflb
Small
Medium
Large
Total
No. plants
using PBS
432
124
_60
616
432
124
_6Q
616
1,080
310
150
1,540
432
124
_60
616
Cost per
plant, $
80
170
340
80
170
340
80
170
340
80
170
340
Total cost,
$d
34,600
21,100
20.400
76,000
34,600
21,100
20.400
76,000
86,400
52,700
51.000
190,100
34,600
21,100
20.400
76,000
Mesh-pad eliminators0
No. plants
using MPME
0
0
Q
0
0
0
Q
0
0
0
Q
0
648
186
.90
924
Cost per
plant, $
0
0
0
0
0
0
0
0
0
60
180
360
Total cost,
$d
0
0
0
0
0
0
0
0
0
0
0
0
38,900
33,500
32.400
104,800
Total
nationwide
cost, $d
34,600
21,100
20.400
76,000
34,600
21,100
20.400
76,000
86,400
52,700
51.000
190,100
73,400
54,600
52.800
180,800
aCosts are based on estimates of $40 per 55-gal drum for transportation, $55 per 55-gal drum (including
10 percent tax) for disposal and capital recovery factors of 0.1628 for packed-bed scrubbers and 0.3154 for
mesh-pad mist eliminators.
"Frequency of packing material replacement is estimated to be 10 years. Volumes of packing material for each
plant size are given in Table 6-13 in Chapter 6.
cFrequency of mesh pad replacement is estimated to be 4 years. Volumes of mesh pads for each plant size are
given in Table 6-13 in Chapter 6.
dNumbers may not add exactly due to independent rounding.
7-93
-------
TABLE 7-36. ANNUALIZED HAZARDOUS WASTE TRANSPORTATION AND
DISPOSAL COSTS ATTRIBUTABLE TO THE CONTROL OPTIONS BASED ON
THE USE OF SINGLE PACKED-BED SCRUBBERS OR MESH-PAD MIST
ELIMINATORS FOR DECORATIVE CHROMIUM PLATING OPERATIONSa
(November 1988 Dollars)
Packed-bed scrubbersb
Plant size
Op "on I
Small
Medium
Large
Total
Option Ha
Small
Medium
Large
Total
Option nb
Small
Medium
Large
Total
Option in
Small
Medium
Large
Total
Option IV
Small
Medium
Large
Total
No. plants
using PBS
1,008
189
63
1,260
1,344
252
84
1,680
1,008
189
63
1,260
0
0
0
0
0
0
0
0
Cost per
plant $
80
160
240
80
160
240
80
160
240
0
0
0
0
0
0
Total cost,
$d
80,600
30,200
15.100
126,000
107,500
40,300
20.200
168,000
80,600
30,200
15.100
126,000
0
0
0
0
0
0
0
0
Mesh-pad mist eliminators0
No. plants
using MPME
0
0
0
0
0
0
Q
0
336
63
21
420
0
0
0
0
0
0
0
0
Cost per
plant, $d
0
0
0
0
0
0
60
120
300
0
0
0
0
0
0
Total cost,
$d
0
0
0
0
0
0
0
0
20,200
7,600
6.300
34,000
0
0
Q
0
0
0
Q
0
Total
nationwide
cost, $d
80,600
30,200
15.100
126,000
107,500
40,300
20.200
168,000
100,800
37,800
21.400
160,000
0
0
0
0
0
0
0
0
aCosts are based on estimates of $40 per 55-gal drum for transportation, $55 per 55-gal drum (including
10 percent tax) for disposal and capital recovery factors of 0.1628 for packed-bed scrubbers and 0.3154 for
mesh-pad mist eliminators.
Frequency of packing material replacement is estimated to be 10 years. Volumes of packing material for each
plant size are given in Table 6-14 in Chapter 6.
cFrequency of mesh pad replacement is estimated to be 4 years. Volumes of mesh pads for each plant size are
given in Table 6-14 in Chapter 6.
Numbers may not add exactly due to independent rounding.
7-94
-------
TABLE 7-37. ANNUALIZED HAZARDOUS WASTE TRANSPORTATION AND
DISPOSAL COSTS ATTRIBUTABLE TO THE CONTROL OPTIONS BASED ON
THE USE OF SINGLE PACKED-BED SCRUBBERS OR MESH-PAD MIST
ELIMINATORS FOR CHROMIC ACID ANODIZING OPERATIONS3
(November 1988 Dollars)
Packed-bed scrubbers'1
Plant size
Option I
Small
Large
Total
Option Ha
Small
Large
Total
Option lib
Small
Large
Total
Option HI
Small
Large
Total
No. plants
using PBS
103
J3
136
360
115
475
103
.33
136
0
0
0
Cost per
plant, $
80
190
80
190
80
190
0
0
Total cost,
$d
8,200
6,300
14,500
28,800
21.900
50,700
8,200
6.300
14,500
0
0
0
Mesh-pad mist eliminators0
No. plants
using MPME
0
0
0
0
0
6
257
_82
339
0
Q
0
Cost per
plant, $
0
0
0
0
60
240
0
0
Total cost,
$d
0
0
0
0
Q
0
15,400
19.700
35,100
0
0
0
Total
nationwide
cost, $d
8,200
6.300
14,500
28,800
21.900
50,700
23,700
26.000
49,600
0
Q
0
aCosts are based on estimates of $40 per 55-gal drum for transportation, $55 per 55-gal drum (including
10 percent tax) for disposal and capital recovery factors of 0.1628 for packed-bed scrubbers and 0.3154 for
mesh-pad mist eliminators.
Frequency of packing material replacement is estimated to be 10 years. Volumes of packing material for each
plant size are given in Table 6-15 in Chapter 6.
°Frequency of mesh pad replacement is estimated to be 4 years. Volumes of mesh pads for each plant size are
given in Table 6-15 in Chapter 6.
Numbers may not add exactly due to independent rounding.
7-95
-------
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7-96
-------
7.8 REFERENCES FOR CHAPTER 7
1. Cost Enclosure for Control Equipment Vendors: Vendor A.
Prepared for U. S. Environmental Protection Agency, Research
Triangle Park, North Carolina. December 31, 1986. pp. 1-2.
2. Letter and cost enclosure from Vendor I to R. Barker,
Midwest Research Institute. November 24, 1988. pp. 3-6.
3. Letter and cost enclosure from Vendor I to R. Barker,
Midwest Research Institute. January 24, 1989. pp. 1-4.
4. Telecon. Barker, R., MRI, to Vendor I. February 21, 1989.
Information on mesh-pad mist eliminator cost data.
5. Cost Enclosure for Decorative Chromium Electroplating
Processes: Vendor D. Prepared for U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
June 18, 1987. p. 4.
6. Cost Enclosure for Decorative Chromium Electroplating
Processes: Vendor E. Prepared for U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
June 5, 1987. p. 4.
7. Cost Enclosure for Decorative Chromium Electroplating
Processes: Vendor F. Prepared for U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
June 22, 1987. p. 4.
8. Cost Enclosure for Decorative Chromium Electroplating
Processes: Vendor H. Prepared for U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
June 22, 1987. p. 4.
9. Monthly Energy Review. Energy Information Administration.
Department of Energy. Washington, D.C. October 1988.
10. Telecon. Caldwell, M.J., MRI, with Kraft, G., American
Water Works Association. March 13, 1989. Information
regarding nationwide residential and commercial water rates
for January 1989.
11. Telecon. Barker, R., MRI, to Jones, R., Ashland Chemical
Corporation. Raleigh, North Carolina. June 1, 1989.
Information concerning industrial-grade chromic acid costs.
12. Supplement to Employment and Earnings, Bureau of Labor
Statistics. August 1988. p. 55.
13. Monthly Labor Review, Bureau of Labor Statistics,
Volume 112, Number 1. January 1989.
7-99
-------
14. EAB Control Cost Manual (Third Edition), U. S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
Publication No. EPA 450/5-87-001A, February 1987. pp. 2-1
through 2-33.
15. Cost Enclosure for Fume Suppressant Vendors: Vendor D.
Prepared for U. S. Environmental Protection Agency, Research
Triangle Park, North Carolina. February 20, 1987. p. 2-3.
16. Cost Enclosure for Fume Suppressant Vendors: Vendor E.
Prepared for U. S. Environmental Protection Agency, Research
Triangle Park, North Carolina. February 2:6, 1987. p. 2-3.
17. Cost Enclosure for Fume Suppressant Vendors: Vendor F.
Prepared for U. S. Environmental Protection Agency, Research
Triangle Park, North Carolina. January 20, 1987. p. 2-3.
18. Cost Enclosure for Fume Suppressant Vendors: Vendor G.
Prepared for U. S. Environmental Protection Agency, Research
Triangle Park, North Carolina. January 20, 1987. p. 2-3.
19. Cost Enclosure for Fume Suppressant Vendors: Vendor H.
Prepared for U. S. Environmental Protection Agency, Research
Triangle Park, North Carolina. February 9, 1987. p. 2-3.
20. Cost Enclosure for Control Equipment Vendors: Vendor B.
Prepared for U. S. Environmental Protection Agency, Research
Triangle Park, North Carolina. February 18, 1987.
21. Cost Enclosure for Control Equipment Vendors: Vendor C.
Prepared for U. S. Environmental Protection Agency, Research
Triangle Park, North Carolina. August 25, 1987.
22. Telecon. Barker, R., MRI, to Welch, P., Duall Industries,
Owosso, Michigan. March 30, 1989. Information regarding
scrubber packing lifetime and replacement costs.
23. Telecon. Caldwell, M.J.,, MRI, with Glovernor, S., Chemical
Waste Management. April 11, 1989. Information regarding
disposal and transportation costs for solid hexavalent
chromium wastes.
24. Memo from Barker, R., MRI, to Smith, Andrew, EPA/ISB.
May 20, 1988. Trip report for Universal Gym and Nissan
Company, Cedar Rapids, Iowa.
25. Neveril, R. B., Card, Inc. Capital and Operating Costs of
Selected Air Pollution Control Systems. Prepared for U. S.
Environmental Protection Agency, Research Triangle Park,
North Carolina. Publication No. EPA-450/5-80-002. December
1978. p. 3-3.
7-100
-------
26. Telecon. Barker, R., MRI, to Sharpies, T. , OMI™/Udylite
International Corporation, Michigan. December 4, 1989.
27. Telecon. Barker, R., MRI, with Welch, P., Duall Industries.
April 28, 1989. Retrofit costs as a percentage of new
facility costs.
28. Telecon. Caldwell, M. J., MRI, with Hankinson, K., KCH
Services. May I, 1989. Retrofit costs as a percentage of
new facility costs.
29. Telecon. Caldwell, M. J., MRI, with Zitko, L., ChromeTech,
Inc. May 1, 1989. Retrofit costs as a percentage of new
facility costs.
30. Telecon. Barker, R., MRI, to Glovernor, S., Chemical Waste
Management, Anaheim, California. September 16, 1987.
Information about hexavalent chromium plating solution
disposal costs.
31. Environmental Pollution Control Alternatives: Reducing
Water Pollution Control Costs in the Electroplating
Industry. U. S. Environmental Protection Agency,
Washington, B.C. EPA Publication: 625/5-85-016.
September 1985. p. 7.
32. Development Document for Effluent Limitations Guidelines and
Standards for the Metal Finishing Industry. U. S.
Environmental Protection Agency, Washington, D.C. EPA
Publication: 440-1-83-091. June 1983. p. V-12.
33. U.S. Department of Labor. Code of Federal Regulations.
29 CFR 1910.1000. Washington, D.C. July 1, 1986. p. 659.
7-101
-------
8 . ECONOMIC IMPACTS
This chapter describes the economic profile for chromium
electroplating operations and the anticipated economic effects of
setting a National Emission Standard for a Hazardous Air
Pollutant (NESHAP) for hard and decorative chromium
electroplating and anodizing operations. The information
provided earlier in Chapter 7 (Cost of Pollution Control) and
below in Section 8.1 (Industry Economic Profile) is the basis for
a formal analysis of the economic effects of the control options
on chromium electroplaters and anodizers. This analysis is
presented in Section 8.2. The references for Chapter 8 are
provided in Section 8.3.
6.1 INDUSTRY ECONOMIC PROFILE
8.1.1 Background
In general, the process of chromium electroplating involves
submerging the object to be plated in a chromic acid solution and
then applying an electrical current to make the chromium adhere
to the object. Anodizing refers to a similar process for
aluminum parts where an oxide is created on the surface of the
part. Thousands of different products are chromium plated in the
United States. Chromic acid anodizing operations are
predominately used in the aircraft industry. Products are
chromium plated either by firms specializing in hard and/or
decorative electroplating operations (job shops), or byfirms that
have electroplating operations as one stage of production within
a larger manufacturing operation (captive shops).
Chromium electroplating is better defined as a process than
as an industry. Firms specializing in electroplating are
primarily job shops and are classified as a distinct industry
group (Standard Industrial Classification [SIC] Code 3471). A
8-1
-------
larger number of firms in other industry groups also perform
electroplating operations. Based upon data from a Bureau of the
Census report and other data sources, more than 200 different
industry groups (4-digit SIC codes) engage in electroplating
operations.:
Chromium plated or anodized products are either
intermediate products, capital goods used in the production
process, or final products. These different stages in the
production process in which electroplating services might be
performed are illustrated in Figure 8-1. Electroplating services
may be provided at any stage of production.
How a product is used determines whether it is an '
intermediate or final product. Generally, if an item is a
component of, or attached to, another unit, it is classified as
an intermediate product. By this definition, automobile bumpers
and other items that are attached to an automobile are considered
intermediate products because they are parts of the final
product, i.e., the automobile. Similarly, industrial rolls and
hydraulic cylinders are intermediate products be;cause they are
component parts of capital goods. On the other hand, a kitchen
faucet (or any other plumbing fixture) can be classified as
either an intermediate or final product. For example, faucets
sold as part of a house are considered intermediate products,
while faucets sold separately in home improvement markets are
categorized as final products.
Most chromium plated or anodized products are either
intermediate products or capital goods. Consequently, any costs
associated with the regulation of chromium electroplating and
anodizing will have much less of an effect on the price of final
products than on the price of intermediate products or capital
goods.
8.1.2 Chromite Ore Supply and Demand
The chain of production that eventually leads to chromium
electroplating starts with the mining of chromite ore. The major
world producers of chromite ore are the Republic of South Africa
8-2
-------
Final
Product
Intermediate
Products
Capital Goods
E
L
E
C
T
R
0 or
P
L
A
T
I
N
G
A
N
0
0
I
z
I
N
G
Labor, Raw Materials,
ana Other Inputs
Figure 5-1. Electroplating, Anodizing, and the Production Process,
-------
and the Union of Soviet Socialist Republics. Together, these two
countries accounted for about 67 percent of total world
production of chromite ore in 1988. Other countries that produce
far smaller but still significant amounts of chromite ore include
Albania, Finland, India, Turkey, and Zimbabwe.2 According to the
U.S. Bureau of Mines, world chromite reserves, especially those
in Africa, are more than adequate to meet forecast world demand
through the year 2000 and beyond.3
The United States imports all of the chromite ore that it
uses. The Republic of South Africa provides about half of the
chromite ore used by the U.S., with the other half divided among
6 to 12 other countries.4 Although the total world supply of
chromium is more than adequate, potential interruptions in
supplies to the U.S. have been a source of longstanding concern.
This concern is an outgrowth of changing world political
conditions, as well as the long and vulnerable nature of the
supply routes in a time of military emergency. Exporting of
chromite ore in various forms from the U.S. does occur, but is
not a major factor.
Most chromite ore is used in the steel industry to produce
stainless steel. Other industries that use chromite ore include
the refractory industry and the chemical industry. Only about 3
to 4 percent of the total chromium consumed in the U.S. is used
for plating and anodizing.5 Table 8-1 presents the amounts of
chromite ore consumed by various end-uses.
Table 8-2 shows that the amount of chromite ore used for
plating ranged from 13,000 metric tons (14,000 short tons) in
1971 and 1975 to 18,000 metric tons (20,000 short tons) in 1979
and 1980, and averaged about 15,600 metric tons (17,500 short
tons) per year.5 After 1981 the U.S. Bureau of Mines stopped
keeping aggregate information about the total amount of chromite
ore used in plating because plating represents such a small
volume and percentage of the total U.S. deraand for chromite ore.
Total demand figures for 1982 through 1989 were gathered from the
U.S. Salient Chromium Statistics.678
8-4
-------
TABLE 8-1. CHROMITE ORE END-USES (1981)*
Plating
Refractories
Chemicals
Other
Metallurgical
Total
Percent of total
amount demanded
4
5
12
13
66
100
Amount demanded**
16 (18)
26 (29)
56 (62)
59 (65)
306 (336)C
463 (510)
aAfter 1981, the U.S. Bureau of Mines stopped reporting demand by end-use.
^Amount demanded is given in 103 metric tons, followed by the English
system eauivalent (103 short tons) in parentheses.
cAmoua* demanded by metallurgical ena-uses is broken down as follows:
Transportation 94 (103)
Construction 86 (95)
Macninery 82 (90)
Housenold Appliances 44 (48)
8-5
-------
TABLE 8-2. U.S. DEMAND FOR CHROMIUM PLATING
AS A PERCENT OF TOTAL U.S. DEMAND FOR CHROMITE ORE
Year
Total demana* Plating of metals* Plating as % of total
1971
1972
197.3
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
310 (341)
462 (508)
498 (548)
509 (560)
338 (372)
430 (473)
473 (520)
495 (544)
500 (550)
486 (534)
413 (455)°
545 (600)
325 (358)
510 (561)
242 (266)
315 (346)
338 (372)
366 (403)
384 (422)a
13 (14)
16 (18)
16 (18)
15 (17)
13 (14)
U (16)
16 (18)
17 (19)
18 (20)
18 (20)
16 (18)
NAC
NAC
NAC
NAC
MAC
NAC
NAC
NAC
4
4
3
3
4
3
3
3
4
4
4
NAC
NAC
NAC
NAC
NAC
NAC
NAC
NAC
aF1gures are given in
eauivalent (103 snort
^These figures differ
snort tons) snown in
snort ton) secondary
ana -inaustnal wastes
to the marxet.
cAfter 1981. the U.S.
cnromue ore used in
a£sfi mated
103 metric tons, followed by the English system
tons) in parentheses.
from the total of 463,000 metric tons (510,COO
Table 8-1 because the 50,000 metric ton (55.000
suooiy is excluded. Recycled chromium alloys
return small quantities of secondary chromium
3ureiu of M'ines stopped reporting the amount of
Dlating.
-------
8.1.3 Chromic Acid Supply and Demand
The next step in the chain of production leading to
chromium electroplating is the production of chromic acid.
Currently, two companies, American Chrome and Occidental Chemical
Company (formerly owned by Diamond Shamrock Corporation), are the
only domestic producers of chromic acid.9 American Chrome
produces chromic acid at its plant in Corpus Christi, Texas. The
plant has a capacity of 21,000 metric tons (23,100 short tons)
per year. Occidental Chemical produces chromic acid at its plant
in Castle Hayne, North Carolina. The Occidental Chemical plant
has a capacity of 42,000 metric tons (46,200 short tons) per
year. Until 1985, Allied Corporation produced chromic acid at a
plant in Baltimore, Maryland, with a capacity of 20,900 metric
tons (23,000 short tons) per year. In July 1985, Allied
Corporation closed its plant in Baltimore and withdrew from the
market. Allied's withdrawal from the market has helped to
alleviate domestic overcapacity.
There is no direct relationship between chromic acid demand
and economic conditions in the metal finishing industry. This is
due in part to increased recycling of chromic acid by this
industry in response to water pollution control regulations.
Moreover, other industries also use chromic acid. Of the 34,500
metric tons (38,000 short tons) of chromic acid demanded in 1984,
the metal finishing_industry accounted for about 39 percent of
consumption, the wood preservatives industry accounted for about
44 percent, other industries accounted for about 6 percent, and
exports accounted for about 11 percent. Growth in demand for
chromic acid by the metal finishing industry was expected to
range from 0 to 2 percent per year through 1989.10
The price of chromic acid remained stable at $2.52 per kg
($1.10 per Ib) through 1989.9 Among the various cost components
for electroplating or anodizing (labor, utilities, etc.), the
cost of other components is greater than the cost of chromic
acid, although any item that affects operating cost is important.
1-7
-------
8.1.4 Suppliers of Electroplating and Anodizing Chemicals
After production by chromic acid manufacturers, the acid is
sold by suppliers of electroplating chemicals to chromium
electroplating and anodizing operations. The suppliers of the
acid sell it primarily in flake form and occasionally in
combination with other chemicals in their proprietary plating and
anodizing solutions. There are over 100 firms in the U.S. that
supply chemical solutions for chromium electroplating and chromic
acid anodizing. Table 8-3 lis;ts nine of the major suppliers (in
alphabetical order) and their headquarters locations.11 Most of
the major suppliers have branch locations throughout the U.S.
8.1.5 Chromium Electroplating and Anodizing Firms and Plants
The following discussion presents estimates of the number
of chromium electroplating firms nationwide. Because the number
of chromium electroplaters is large, a brief overview is
presented below to provide a framework for considering the total
number of firms.
8.1.5.1 End-Use Industries for Chromium Electroplating.
Chromium plated products are used in a large number of
industries. For example, the market for chromium plated products
covers 17 two-digit SIC codes. Each two-digit SIC code category
includes such a broad group of industries that the code's
usefulness is limited for an economic analysis of chromium
electroplating, specifically. Therefore, the information that
follows is presented at the more detailed four-digit SIC code
level.
In September 1985, the Bureau of the Census released a
report covering captive metalworking operations, including
electroplating establishments, that are present in various
industries.1 The Census report defines 184 industries involved
in metal work that perform electroplating operations. This
report does not include job shops (SIC 3471), i.e.,
establishments specializing in electroplating operations, in
contrast to the regular Census; report which does provide
statistical data on job shops. Instead, the September 1985
-------
TABLE 8-3. MAJOR SUPPLIERS OF CHROMIUM ELECTROPLATING CHEMICAL SOLUTIONS
Company name
Headquarters location
American Chemical & Refining Co., Inc.a
C.P. Chemicals, Inc.
Enthone, Inc.b
The Lea Manufacturing Co.
Lea-Ronal, Inc.
The O.T. MacOermid Grouo
M&T Chemicals, Inc.
McGean-Rohco, Inc.c
Shipley Co., Inc.
Waterfcury, Connecticut
Sewaren, New Jersey
west Haven, Connecticut
Watertury, Connecticut
Freeport, New York
Plymouth, Connecticut
Rahway, New Jersey
Cleveland, Ohio
Newtown, Massachusetts
*A Handy i Hannon Company.
^Subsidiary of ASARCQ. Inc.
cOuPont sold its Business ta this company.
P-Q
-------
Census report defines the number of establishments in other
industry categories engaged in electroplating operations as a
part of a larger process. The Census report is useful because it
covers a large number of SIC groups, identifies the total number
of establishments for each SIC group, and identifies the subset
of establishments that perforir. electroplating.
8.1.5.2 Number of Chrorr.e Electroplating Establishments.
There are no sources that provide an industry-wide estimate of
the number of chromium electrcplaters. However,, there are three
sources that provide information about the percentage of all
electroplaters that perform chromium electroplating. The first
source is the American Electrcplaters and Surface Finishers Shop
Guide, which indicates that of 1,103 firms listed, 521 firms or
47 percent perform chromium electroplating. The second source is
the EPA report developed for the electroplating pretreatment
standards, which indicates that about 40 percent of all
electroplaters perform chromium electroplating.12 The third
source is Finishers/ Management, which reports that of the 4,022
metal finishing job shops in the U.S., 2,092 or 52 percent are
engaged in chromium electroplating.13 Finishers' Management
gathered their data by surveying the yellow pages along with SIC
codes. Combining the Finishers' Management data with data from
the 1982 Census of Manufactures for electroplating operations
shows the estimated nationwide number of chromium plating
operations to be 4,340.a About 52 percent of the chromium
operations are captive and the remaining 48 percent are job
shops. About 58 percent of the job shops are engaged in
decorative chromium plating, and about 71 percent of the captive
shops perform decorative electroplating.
8.1.5.3 Chromium Anodizing Plants. For chromic acid
anodizing, the total number of operations nationwide is estimated
to be 680, of which 74 percent are classified as job shops and 26.
'See Tables in Chapter 7.
8-10
-------
percent are classified as captive shops.b
8.1.6 Size and Geographical Distribution of Chromium
Electroolaters and Anodizers
Chapter 5 presents a breakdown of the estimated number of
hard chromium plating, decorative chromium plating, and anodizing
operations by plant size. Of the estimated 1,540 hard chromium
plating operations, small plants constitute 70 percent, medium
plants 20 percent, and large plants 10 percent. Of the estimated
2,800 decorative chromium plating operations, small plants
constitute 80 percent, medium plants 15 percent, and large plants
5 percent. Of the estimated 680 chromic acid anodizing
operations, small plants constitute 75 percent and large plants
25 percent.
Before discussing specific employment data as the indicator
of size, a brief discussion of terminology is necessary.
Depending on the source of the information, employment data are
typically presented using any one of three definitions: firm
employment, establishment employment, and electroplating
production worker employment. Firm employment refers to total
employment for a company, including all company divisions and all
locations if a company has multiple locations. Establishment
employment refers to an individual plant, even though a single
company might have multiple plants. Electroplating production
worker employment refers to only those employees directly
involved with electroplating, even though a given plant might
have numerous additional employees engaged in other operations,
and it excludes all supervisory personnel.
Most electroplating establishments are small. The number
of production workers required to operate a single electroplating
operation, either a captive operation or a job shop, is typically
less than 100 employees. Frequently the electroplating operation
involves less than 50 employees, and often less than 20. In the
case of job shops, many firms have 10 or fewer employees. The
'See Table in Chapter 7.
8-11
-------
use of automated electroplating production lines can obscure the
relationship between an operation's size and the number of its
employees. Even taking automation into consideration, however,
there are many small operations.
Products Finishing14 provides size distribution information
based on employment specific to chromium electroplating. Table
8-4 presents total employment of the firm data. The Products
Finishing information shows that in 1985, 52 percent of the
chromium firms had less than 100 employees.14
The Census report covering SIC 3471 includes employment
data on an annual basis from 1972 through 1987. The data for the
years 1972 through 1987 show that employment in plants employing
20 or more reached a peak in 1987 with 71,100 total employees and
55,900 production employees.15
Electroplaters are geographically dispersed across the U.S.
with most electroplaters located near population and
manufacturing centers and not near the sources of raw materials.
In 1987, the top eight States in terms of number of workers were
California, Ohio, Michigan, Illinois, New York, Texas,
Pennsylvania, and New Jersey.16 Collectively, these States
represent 62 percent of the total of electroplating production
workers in the U.S. The top four States have 42 percent of the
total of electroplating production workers. Table 8-5 shows the
1982 distribution by State of electroplating production workers
(at all types of electroplating establishments) across the U.S.
8.1.7 Substitutes
In many industrial hard plating applications, there is no
satisfactory substitute for chromium. In selected applications,
chromium alloys can take the place of hard chromium plating. For
plating applications that emphasize corrosion resistance,
electroless nickel can be substituted for chromium, based on
technical performance. In plating applications that emphasize
wear or abrasion resistance, hard chromium typically has superior
performance characteristics and, in these cases, the ability to
substitute electroless nickel ::or chromium is not as great.
8-12
-------
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State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
District
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
-------
TABLE 8-5. (continued)
Bureau of
the census (1982)
Electroplating
production workers
(all types of
State establishments)
Pennsylvania 1,500
Rhode Island 1,700
South Carolina NR
South Dakota NR
Tennessee 1,200
Texas 1,900
Utah NR
Vermont NR
Virginia 200
Washington 500
West Virginia NR
Wisconsin —&
Wyoming NR
U.S. Possessions NR
Total 49,700C
aNR«not reported.
tuithneld by Census.
clnatvici;al states co not sum to total due to withheld information.
-------
Also, electroless nickel is significantly more expensive than
chromium and, consequently, economics imposes a constraint on
substitution.17
Examples of applications where electroless nickel is a
potential substitute for hard chromium include cylinders and
rolls used in the printing and textile industries.18 Other
examples include components used in the petroleum and chemical
process industries, where corrosion protection is a major
concern.19 Specific components include blow-out preventers,
chokes, heat exchange equipment, pumps, compressors, tubing,
vessels, packers, and various valves (ball, gate, plug, and
check) ,17
The potential for substitution is much greater in
decorative plating applications, where nickel, cadmium, trivalent
chromium and zinc can be substituted for hexavalent chromium in
some end-uses (see Chapter 5). For selected decorative plating
applications, materials that are not metals can be substituted
for chromium. In some instances paint or a plastic coating can
substitute for chromium plating.
The principle substitute for chromic acid anodizing is
sulfuric acid anodizing.
8.1.8 Imports and Exports
Quantitative information about the import or export of
manufactured products solely for the purpose of chromium
electroplating or anodizing is not available. In general,
however, it appears to be uncommon for products manufactured in
one country to flow to another country solely for the purpose of
chromium electroplating. This is not to say that products
manufactured in the U.S. are never sent to foreign countries for
chromium electroplating and then returned to the U.S. for sale,
but in most cases the possible savings in the cost of
electroplating would be more than offset by transportation costs.
Shipping of automobile parts to Canada may be an exception to
this pattern.
One relatively recent development with potential economic
8-16
-------
implications for domestic electroplaters is the introduction of
water pollution control regulations with various compliance
deadlines that ranged from 1984 through 1986.21 Because the
regulations are a recent development, actual results have not
yet been measured. Preliminary indications, however, do not
suggest that these water pollution regulations have led to an
increase in the use of foreign chromium electroplating.
8.1.9 Profile of Selected Product Markets in Chromium
Electroplating
Because so many products are chrome plated, it is not
feasible to describe and analyze them all. Therefore, this
section provides economic profile information for several
specific markets for five chromium plated products.
The five products were selected based on the following
criteria:
o Representation of a variety of industries
o Consideration of a relatively broad price range
o Emphasis given to products having a high chromium plating
cost relative to the final price of the product (when the
information available permitted the identification of
such products)
o Representation of both decorative and hard chromium
plated products
o Inclusion of at least one capital good, at least one
intermediate product, and-at least one final end-product
o Representation of a relatively large share of the total
number of firms that perform chromium electroplating
o Inclusion of a mixture of job shops and captive
operations.
Given these criteria, the five products examined in detail
are plumbing materials, hand tools, automobile parts, industrial
rolls, and hydraulic cylinders.
The characteristics of the products are discussed in the
8-17
-------
following subsections. Plumbing materials and hand tools are
decorative chromium plated products. Some automobile parts are
decorative chromium plated products, while others are hard
chromium plated products. Industrial rolls and hydraulic
cylinders are hard chromium plated products.
8.1.9.1 Plumbing Materials. The plumbing material market
is an end-use market for decorative chromium plating. This
market is classified under SIC 3432, "plumbing fixture fittings
and trim (brass goods)." It includes items such as plumbers'
drains, metal faucets, nozzles, and lawn sprinklers. Plastic
pipe fittings are not included in this SIC group.
Table 8-6 presents data on the value of shipments of
plumbing fixtures for the years 1982 through 1987.x 22 As the
table shows, thetotal value of shipments for the industry was
$2.2 billion in 1987.
Although the industry includes several types of products,
chromium plated metal faucets represent one of the major
products. A majority of all metal faucets are plated with
chromium. Faucets are available with a polished brass finish or
zinc plating as alternatives to chromium plating. Also, plastic
faucet handles are available. In 1989, the faucet market is
estimated to have increased by about 8 percent, from
approximately $404 million in 1988 to $436 million in 1989.23
In the past, faucets have usually been sold almost
exclusively through plumbing wholesalers, who then sell to
plumbers, builders, and remodelers. More recently, an increasing
share of faucets has been sold, directly to consumers through
retail outlets that cater to the do-it-yourself market.
The demand for faucets depends on both new construction and
the replacement/remodeling market. Approximately 45 percent of
all faucets sold are for new construction, while the remaining 55
percent are sold in the replacement/remodeling market. Of the 45
percent sold for new construction, 30 percent are for residential
construction (based on five fs.ucets in each new single-family
unit) , and the remaining 15 percent are for new commercial,
8-18
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institutional, and industrial construction.
8.1.9.2 Hand Tools. Another significant market for
chromium plating is the manufacture of hand tools. Hand tools
can be chromium plated for decorative or functional purposes.
The hand tools category includes products such as pliers and
wrenches. The principal SIC group is 3423, "hand and edge tools,
except machine tools and hand saws." Hand tools are the
principal products of interest, but there are also three other
closely related SIC categories that are applicable: SIC 3421,
"cutlery"; SIC 3425, "saw blades and hand saws"; and SIC 3429,
"hardware, not elsewhere classified."
For the majority of tool manufacturers surveyed, the best
selling hand tools (in terms of number of units sold
domestically) are ratchets and sockets. Both of these products
are decorative chromium plated to prevent tarnish, produce an
abrasion resistant surface, and coat the product with an
appealing mirror finish. Sockets and ratchets are made of
low-carbon steel which is nickel plated for corrosion resistance.
Tape measures are also sold in large numbers. A tape measure
case is typically ABS plastic which is then chromium plated.
Hand tools might be more sensitive to pollution control
costs than the other four products selected for analysis because
they are final products and their price is generally lower than
that of the other products.
The market for hand tools is segmented into two broad
categories: a professional market and a do-it-yourself market.
These markets overlap to some extent. The size of the United
States' market for all hand tools was estimated to be about $3.6
billion in 1987 (based on value of shipments) ,24
8.1.9.3 Automobile Parts. The automobile; industry is
commonly considered to be the most important end-use market for
decorative chromium electroplating. The automobile industry uses
chromium electroplating for a variety of parts, including
automobile bumpers (SIC 3465, automotive stampings), grilles,
headlamp and tail-light bezels, door handles;, side-view mirrors,
8-20
-------
stick shifts, wheels, and wheel covers. Also, some engine parts
and other parts, such as piston rings, MacPherson Struts, and
shock absorber components, are chromium plated. Engine parts,
such as air filter covers, are chromium plated for decorative
purposes, while other engine parts, such as piston rings, are
chromium plated for functional purposes.
The demand for chromium plating in the U.S. automobile
industry is influenced by the quantity of automobiles produced in
the U.S., as well as by other forces, such as the desire for
greater fuel efficiency and changes in the tastes of consumers.
As shown in Table 8-7, the total domestic production of
automobiles reached its peak in 1973 at 9.7 million cars and
declined to as low as 5.1 million cars in 1982."
The volume of domestic truck and bus production is
substantially smaller than (i.e., less than one-half) the volume
of domestic passenger car production. While the market for
trucks and buses has experienced growth, the import share varies
from .3 percent for the heavy duty (over 15,000 kg [33,000 Ib])
trucks to 12.8 percent for the light-duty (0-6,400 kg [0-14,000
Ib]) trucks to 13.7 percent for the medium duty trucks.26
Therefore, the truck and bus market which is subject to the same
import pressure as the passenger car market, results in a
fluctuating domestic demand for chromium plating. Exporting of
automobiles and trucks produced in the U.S. does occur, but is
not a major factor.
Measures to promote fuel efficiency have also influenced
the demand for chromium plating. During the past decade,
government directives, such as the corporate average fuel economy
(CAFE) requirements, have imposed fuel efficiency standards on
automobiles produced and sold in the U.S. Consequently, more
plastics, less steel, and more aerodynamic designs have been used
in automobile production in the U.S. Whereas most automobile
bumpers were formerly chromium plated steel, an increasing number
of them are now made of plastic. While some of the plastics now
being used by the automobile industry are chromium plated
8-21
-------
TABLE 8-7. ANNUAL U.S. MOTOR VEHICLE PRODUCTION
. Year
1988
198*7
1986
1985
1984
1983
1982
1981
i960
1975
1978
1977
1375
1375
137.1
1972
1372
1371
1 970
Passenger
cars
(number of units)
7,110,728
7,098,910
7,828,783
8,184,821
7,773,332
6,781,124
5,073,496
6.253,133
S.J75.5C5
3,433,552
9,176.525
9,213,554
8,497.333
6,716,351
7,324,5:4
9,667.152
8,828.2:5
8,583,553
5,550.123
Motor trucks
and buses Total
(nutnoer of units) vehicles
4,079,704
3,825,776
3,505,992
3,465,500
3,151.449
2,443,637
1,912,099
1,689,778
1,634,335
3,046,331
3,722.567
3,489,128
2.999,703
2,269,552
2,746,538
3,014,351
2,482,503
2,088,001
1.733,821
11.190,432
10,924,686
11,334,775
11,650,321
10,924,781
9,224,821
6,985,595
7,942,916
8,009,841
11,479,993
12.899,202
12.702.782
11,497,596
3,986,513
10,071,042
12,581,513
11.210,708
12,571,654
3,283,949
Source: Motor
vehicle Manufacturers Association of the U.S., Inc.
8-22
-------
(examples are plastic grilles and knobs), overall there has been
a decline in the amount of chromium plating performed by the
automobile industry.
Finally, the preference of consumers for more or less
chromium plating on automobiles may be another important
determinant of the demand for chromium plating in the automobile
industry. In general, the taste of consumers over approximately
the last 10 years has shifted to a desire for less chrome on
automobiles. For example, in 1974, 90 percent of the automobiles
produced in the U.S. had chromium plated bumpers, but in 1985 the
number had declined to only 50 percent.27 Despite these trends,
the automobile industry is probablystill the largest user of
chromium plated products in the U.S.
8.1.9.4 Industrial Rolls. Numerous industries use rolls,
including foil, food processing, magnetic tape, metal forming,
paper, plastics, printing, textiles, and wallpaper. Rolls can be
used for a wide variety of purposes, depending on the particular
industry. They can be used for heating, cooling, pressing,
coating, and drying. The plating and replating of industrial
rolls represents a sizable market for hard chromium plating.
Rolls are typically made of steel, stainless steel, or aluminum.
The rolls are available in a wide size range, i.e., lengths of
from only a few inches to over 12 m (40 ft), diameters of from
only a few inches to about 2 m (8 ft), and weights up to 50 tons.
There is no "standard size" roll because the size of the roll
varies depending on the industry involved and the application.
Defining the size of the market for industrial rolls is
difficult because the rolls are used in many different
industries, and because the function of the rolls can vary among
the industries. Additionally, an industrial roll is only one of
many components entering into the production of a finished piece
of equipment.
Over 100 firms plate industrial rolls with chromium. The
industry includes a mixture of firms, some of which only plate
rolls manufactured by others, while others both manufacture and
8-23
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plate rolls. The firms are dispersed across the United States.
Approximately 6 to 10 firms account for a major share of the
domestic market, perhaps greater than 50 percent. The larger
firms cover a marketing territory that includes the entire U.S.
and occasionally other countries. The smaller firms are
typically regional.
Rolls are both imported and exported. Sweden, Germany, and
Brazil are among the countries that export rolls to the U.S. The
U.S. exports rolls to Japan and other countries. The exact
quantity and value of imports and exports is not available.
However, in general, the import: and export activity for rolls
does not appear to be significant. Most rolls used in the U.S.
are manufactured and chromium plated in the U.S.
With respect to hard chromium plating, industrial rolls are
significant for two reasons. First, the number of rolls
manufactured is large; therefore, rolls are an important source
of demand for hard chromium plating. Second, existing industrial
rolls are rechromed periodically, thus providing an additional
source of demand for hard chronium plating. The frequency of
rechroming varies depending on the application.
8.1.9.5 Hydraulic Cylinders. An important market for hard
chromium plating is the manufacture of hydraulic cylinders.
Hydraulic cylinders are one of the products manufactured by firms
in SIC 3593, "fluid power cylinders and actuators." Because
other products, in addition to hydraulic cylinders, are produced
by firms in SIC 3593, information about this SIC group that might
be available from other sources is frequently not a direct
representation of the hydraulic cylinder market.
Information about the hydraulic cylinder market is scarce
because a hydraulic cylinder is; only one of many components
entering into the production of. a finished piece of equipment.
Hydraulic cylinders are frequently reported within a broader
category of items commonly referred to as fluid power products.
For example, the principal trade association for the
manufacturers of hydraulic cylinders is the National Fluid Power
8-24
-------
Association.
Many industries use equipment having hydraulic cylinders.
Among users of hydraulic cylinders are the construction, nuclear,
mining, oil drilling and marine industries/ agriculture, and the
military.
Hydraulic cylinders have a variety of functions, including
pushing, pulling, lifting, compensating, tensioning, positioning,
and absorbing. The sizes of hydraulic cylinders can vary over a
wide range, from a length of only a few inches to over 6 m (20
ft) and from a diameter of only a few inches to more than 1 m (3
ft). Cylinder sizes vary from industry to industry depending on
the application. Therefore, there is no standard size cylinder,
but most cylinders are probably only a few inches in diameter.
There are approximately 80 firms that manufacture hydraulic
cylinders.28 As shown in Table 8-8, in 1987 the total value of
shipments of hydraulic and related items was $1.4 billion.29
Hydraulic cylinders are widely used in the construction
machinery industry. Construction machinery is included in SIC
group 3531. The construction machinery industry had an estimated
value of shipments in 1988 of $13,090 million and a 1989 forecast
of $13,352 million.30 The expected growth rate is 2.5 percent
for the rest of the decade. The low expected growth is mainly
due to the unfavorable trade balance for this industry that began
in the late 1970s.
Imports and exports of cylinders do exist. In general,
however, the import and export market for cylinders is not a
major factor in the market. Most cylinders used in the U.S. are
manufactured and chrome plated in the U.S. Cylinders usually are
not rechromed.
8.1.10 Chromic Acid Anodizing
As much as 10 percent of chromium use is for chromic acid
anodizing. Unlike chromic acid electroplating, chromic acid
anodizing is a process wherein an oxide is created on the surface
of an aluminum part in an electrolytic bath of chromic acid.
Military aircraft manufacturers are the largest user of the
8-25
-------
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8-26
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chromic acid anodizing process. Depending on the type of
aircraft, major portions of the airplane's "skin" may be anodized
using chromic acid. Other parts of the aircraft may also be
anodized, e.g., the inside diameter of the hydraulic cylinders.
Because the Department of Defense (DOD) specifically requires
chromic acid anodizing, private contractors to DOD should be able
to pass on all cost increases due to the proposed control options
in the form of higher costs. Thus the impact on the individual
chromic acid anodizers of military products is expected to be
negligible.
The impact of the proposed control options on several
nonmilitary anodized parts will be assessed in Section 8.2.4.6.
8.2 ECONOMIC IMPACT ANALYSIS
8.2.1 Introduction
The principal objective of the economic impact analysis is
to estimate the effects of various control options on the prices
and output of chromium plated or anodized products and
substitutes, as well as on prices, output, and employment in
electroplating and anodizing establishments (either captive or
job shops) . Another set of objectives is to estimate total
control costs for each control option and to estimate any
distributive impacts, such as on small businesses. As explained
in Section 8.1, chromium electroplaters and anodizers are not a
cohesive industry, but a group of firms engaged in a similar
process spread across a variety of industries. Because chromium
electroplating or anodizing is viewed as a process rather than as
a well-defined industry, a methodology which focuses on industry
behavior will not render a useful economic analysis. Therefore,
this section provides ranges of probable values of the price and
output effects for specific products for which the chromium
electroplating or anodizing process is an integral and separable
stage of production.
Five product groups for which chromium electroplating is an
important component were analyzed to illustrate a range of
8-27
-------
probable impacts. The five product groups chosen for analysis
are plumbing materials, hand tools, automobile parts, industrial
rolls, and hydraulic cylinders. This combination of products
covers both hard and decorative plated products. For each of the
product markets, estimates of the impact of the control options
on both the cost of electroplating and the final price were
calculated. The increase in the cost of chromium electroplating
illustrates the potential for substitution away from chromium
electroplating at the input stage. The increase in the final
price of the product allows estimation of output reduction and
the concomitant effects on revenue.
Aggregate economic impacts for all chromium electroplating
processes were expressed as total control costs based on the
estimated number of plants, "he methodology does not permit
direct extrapolation of process-wide price effects or output
reductions because the five product markets are only illustrative
of chromium electroplating activities and not representative of
all chromium electroplating operations.
Chromic acid anodizing was analyzed by examining several
nonmilitary aircraft parts to determine the increase in anodizing
costs for the small and large plants.
8.2.2 Overview
Five product groups were: selected to illustrate the
economic impacts associated with the control options for the
chromium electroplating operations. The product groups selected
include plumbing materials (represented by faucets)/ hand tools
(represented by sockets, ratchets, and tape measures); automobile
parts; industrial rolls; and hydraulic cylinders (represented by
backhoes) . The product groups; were selected to illustrate the
effect of each control option on both hard and decorative plated
products and on both capital and consumer goods. The impact
results are summarized in Table 8-9.
The impacts are greater for products that are hard chromium
plated. Table 8-9 displays worst-case quantitative results from
the most costly control option for the model plant sizes
8-28
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8-29
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incurring the greatest control costs per unit of output, i.e.,
Control Option II or Scenario 1 for trivalent chromium for the
small decorative model plants and Control Option III for the
small hard model plants. (The percentage increases in price for
each control option and each model size plant are presented in
Section 8.2.4.) The estimated increase in the final price of the
selected electroplated or anodized products was always 0.1
percent or less for even the most costly control option.
Substitution away from hard chromium electroplating appears
very unlikely, even though control costs are higher than for
decorative plating, because comparably priced hard chromium
substitutes are not available. Therefore, it is likely that the
costs of the control options for hard chromium electroplating
will in large part be passed on to consumers which as indicated
above results in minimal price increases of 0.1 percent or less.
For the decorative plated products studied, substitution away
from hexavalent chrome to, for example, trivalent chrome or
paint, is likely to accelerate for a product like tape measures.
This is based on the 0.8 percent electroplating cost increase of
the most costly control option and the recent extent to which
tape measures are being successfully decorated by substitute
processes. For the other decorative coated products, the control
costs will in large part be passed on to consumers and will not
lead to substitutes for electroplating or to diminished purchases
of those consumer products.
For purposes of illustration, faucets can be used to
describe the two different effects, summarized above, resulting
from implementation of a control option. The first effect is the
increase in electroplating costs and the second effect is the
increase in the final price of the product for which
electroplating is generally an intermediate process. Assume a
faucet sells for $62.65 and costs $0.42 to electroplate. The
most costly Control Option II results in an approximate $0.015
(3.6 percent) increase in chromium electroplating cost, which
raises the cost of chromium electroplating to $0.435. At this
8-30
-------
cost increase level, faucet manufacturers would have little
incentive to substitute other products for chromium plating
because the closest substitutes cost more than the increase due
to the control options.
Assuming that the $0.015 increase in chromium
electroplating cost is therefore passed on to consumers, the
price of the faucet would increase from $62.65 to $62.67, or by
approximately 0.03 percent under Control Option II. In this
case, the small increase in price for the final product (the
faucet) is not likely to result in a significant reduction in the
number of faucets purchased, nor will it have a significant
impact on the revenues earned by faucet manufacturers.
Cost and price increases for each product studied are
calculated in Section 8.2.4. Section 8.2.5 examines potential
quantity and revenue effects for each of the five products. For
the final products studied, changes in revenues and output are
always well below one percent. Section 8.2.6 reports that the
nationwide costs are a maximum of $88.0 million under the most
costly combination of control options. Section 8.2.7
investigates the possibility of differential impacts on small
businesses. Some small chromium electroplating operations,
particularly hard chromium operations, will face capital
availability difficulties for some regulatory alternatives.
Also, up to 15 of the uncontrolled hard chromium operations are
expected to close if the most stringent control option (i.e.,
Ill) is implemented under worst case conditions.
8.2.3 General Methodology of the Analysis
This section presents the methodology used in estimating
the price and output impacts for chromium electroplating
operations and" chromium plated products. The methodology for
estimating small business impacts is presented in Section 8.2.7.
The analysis first isolates and quantifies the cost of the
control options. Second, it compares the control costs for a
particular control option per unit of model plant output to the
direct costs of chromium electroplating a unit of output to
8-31
-------
determine if electroplating could be replaced by competitive
coatings, materials, or processes. Third, this analysis compares
the same control costs per unit of output to the final (i.e.,
manufacturer's) list price of the product to determine, along
with a demand elasticity coefficient, any likely changes in the
quantity demanded of that product. This step permits estimation
of product-wide output and revenue effects, while the first two
steps provide an assessment of employment and small business
impacts for chromium operators, particularly job shops.
This particular approach implicitly assumes that chromium
electroplating applied to an individual product can be performed
by any size model plant. The primary advantage of adopting this
method is that cost increases associated with a control option
and its subsequent effects on output and revenue can then be
analyzed in the same manner regardless of the product, the firm,
or the market in which the electroplating occurs.*
For each of the five product markets studied, the following
detailed description of the analysis supplements the above
summary. In order to calculate the potential increase in final
price, the increase in the marginal control cost due to each
control option must be estimated for each model plant.b This
calculation consisted of dividing the annualizecl control costs
for a particular size plant by the number of units of output for
that size of plant.
Chapter 5 identifies seven control options for chromium
electroplating, four for decorative chromium electroplating, and
three for hard chromium electroplating. Table 8-10 gives the
capital costs and the annualized control costs for each
aAn implicit assumption is that the electroplating is
performed by the least cost technique consistent with profit
maximization.
bThroughout this analysis,, the average total cost curve is
assumed to be horizontal for a particular size plant; hence the
marginal cost is equal to the average cost (i.e., the cost per unit
was assumed to be constant).
8-32
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TABLE 8-10.
DECORATIVE CHROMIUM PLATING MODEL PLANT COST4 DATA
(1988 $)
Control
Options
Small Model Plant
Capua) Annual Uea
cost, 5 cost, $
Medium Model Plant
" Capital Afrnual lzeo>
cost, S cost. $
Larqe Model Plant
Capital Annual 1zeab
cost, $ cost, S
I
Baseline
or no action 0
uc
Single oaclced-
sea scruocer 45,900
or mesn-oad
mist el inn- 28,900
nators
91,800 24,600 155,900
49,000 19.100 109,100
ChemTcal fume
suocressant,
permanent
:va
Trivalent
Chromium
0 l.CCO 0
Ratchets
66,SOO 23,500 133,900
(11,000)
13,200
3,500
Faucets
29,000
21,800
26,300
0 18,700
Bumoers
565,500 (2,280.000)
36.100
108,900
costs,
~These c:sts were not adjusted for chromic acid recovery costs.
:'Jncerl :nea values reoresent the least-cost controls for Control Option II.
"Three scenarios of annualized costs are presented as a function of product
"eject "ates wnen using the tnvalent cnromium process. Scenario 1 1s
*or a reject rate given cy the plants
Scenario 2 reflects a reject rate set
:y f.e olants. Scenario 2 reflects a
::st Differential is zero.
that produce the specified product.
at the average of the values given
reject rate set so that the process
-------
decorative chromium electroplating alternative. The control
options for hard chromium electroplating are shewn in Table 8-11.
Each model plant has a unique set of capital and annualized
control costs based on its production capacity. The annualized
control costs were computed using a 10 percent discount rate and
an equipment life of 20 years except for mesh-pad mist
eliminators which have a 10-year life.
The costs shown in Tables 8-10 and 8-11 are those for
retrofitting an existing plant. Chapter 7 contains two sets of
costs; retrofit and incremental costs for compliance if building
a new electroplating facility. Retrofit costs are always higher
and were chosen for calculations in all subsequent tables because
retrofits to existing plants is expected to be the most common
form of compliance.
The calculation of the potential increase in final price
was done by first converting the model plant parameter of Ah/yr
to number of units of output for each of the model plants and
each of the five product markets. Tables in Chapter 5 list the
production capacity of each of the model plants in terms of
Ah/yr. The parameters of the products 'selected to illustrate the
impact of the control options were obtained from manufacturers of
the products. These parameters included surface area plated,
current density applied during the plating process, and plating
time. These parametric values allowed an estimation of the Ah
per part needed to plate the surface area efficiently. Because
the model plants' capacities were measured in Ah/yr, and the
products analyzed were measured in Ah per part, an estimate of
the potential output per plant could then be calculated. In
order to allow for the loading of parts in the tanks and general
maintenance of the electroplating facilities, the model plants
were assumed to operate at less than 100 percent of their
capacity. The capacity utilization rates for each plant size are
displayed in Chapter 5.
Next an estimate of the cost per unit output of the
selected product due to chromium electroplating was obtained.
8-34
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TABLE 8-11. HARD CHROMIUM PLATING MODEL PLANT COST* DATA
(1988 $)
=====
Control
Options
I
Ba-sel me or
no action
Smal
Capi
cost
1 Mode
} Plant
tal Annual
, $ cost
0
izea°
, $
0
Medium
Capital
cost, $
0
- — '
Model Plant
Annual
cost
izeau
, S
0
••MBMBM^BVNBBV
Large
Model Plant
Capua!
cost, $
0
Annuahze
cost, $
aj
0
Chevron-olade 29,800
mist eliminator
(dounle)
LLLC
S1nc;e cached- £5,9C3
tea scrucoer
or mesn-oaas
-rust el irrn- 23,900
natcrs
5,700
1,500
62,400 14,700 124,800 33,600
92.800 2.4,200 185,500 54.800
;,EGO 82.500 29,900 156,300 69,000
*Retr:fit costs.
-These ccsts were not aajustea for cnrcmic ac:a recovery costs.
cUncsrl in.ea values reoreseni the least-cost controls for Control Option III
-------
The cost was defined as the direct cost of chromium
electroplating the product or part exclusive of all other costs.
Finally, by dividing the annualized control cost by the
firm's potential output, an estimate of the control cost increase
per unit was derived. This increase in the final price was then
used, along with an assumed or estimated price elasticity, to
obtain an estimate of the reduction in output and the
accompanying effect on the firm's revenue.
Overall, the economics of plating operations is a poorly
understood subject.31 The actual cost of the deposited metal is
generally considered to be a minor factor in the total cost of
plating, and power cost is even less important. Overhead and
labor are the major costs. Hence, it is more important, in a
cost minimizing sense, to deposit the required plating thickness
in the shortest time with the fewest rejections than it is to
economize on chromic acid, plating solution supplies, or power.
Since the proposed pollution control devices are intended
to reduce the emissions from the electroplating operation, the
entire burden of the control costs must first be placed on the
additional cost of electroplating, and not spread over the entire
manufacturing operation. Hence, the analysis first had to
determine if the manufacturers would continue to use chromium
plated parts or switch to a substitute process. If manufacturers
do substitute, the potential impact of the regulation would then
be felt on chromic acid manufacturers and suppliers and
electroplating operators. Substitution away from chromium
electroplating can only occur if a technically and economically
suitable substitute is available. Furthermore, the degree of
substitution possible is significantly less for hard chromium
applications than for decorative chromium.
Control Option II for decorative chromium plating has two
alternatives; each with the same control effectiveness - single
packed-bed scrubbers or mesh-pad mist eliminators. Control
Option III for hard chromium plating also contains the same two
alternatives. Regarding Control Option IV for decorative
8-36
-------
chromium electroplating (substitution of trivalent chromium),
preliminary estimates indicate that the use of trivalent chromium
may confer cost savings or cost increases, depending upon the
reject rate. Three different scenarios are depicted in Table
8-10. Scenario 1 contains costs commensurate with a reject rate
given by the plants that produce the end product shown. The
costs for Scenario 2 reflect a reject rate of the average values
given by the plants and the costs for Scenario 3 reflect a reject
rate that produces a process cost differential of zero over the
costs of the hexavalent chromium process.
8.2.4 Economic Analysis of the Selected Products
This section discusses the economic impact associated with
applying each of the control options to each of five products:
plumbing materials (represented by faucets)/ hand tools
(represented by sockets, ratchets, and tape measures); automobile
parts; industrial rolls; and hydraulic cylinders (represented by
backhoes). The analysis focuses on the effects on the final
price of the product being studied and on the electroplating cost
associated with the control costs of each of the control options.
The two decorative chromium electroplated products — faucets and
hand tools — are presented first. The impact of the control
options on automobile parts, which include both decorative and
hard chromium plated parts, follows. Then, two capital goods
that are hard chromium plated — industrial rolls and hydraulic
cylinders (hydraulic cylinders in backhoes) — are analyzed.
Finally, aviation parts are analyzed for chromic acid anodizing
impacts.
8.2.4.1 Plumbing Materials. The particular product chosen
to represent the plumbing fittings industry was a kitchen faucet.
The particular faucet is single-handled, sells for approximately
$62.67, and is one of the best selling faucets in this market.
At retail outlets, the price range for faucets is $30 to $75 per
unit.
As stated in the general methodology section, two values
had to be calculated to assess the economic impact of the control
-------
options: first, the cost of electroplating the product and
second, the compliance cost per unit produced due to the
pollution control device used.
A computer program was used to assist in calculating the
unit cost of chromium electroplating per faucet based on surface
area, current density, production rate, and plating time.32 The
faucet used for the analysis is assembled from four separate
chromium plated parts with a total surface area of 500 cm2 (77.5
in.2). The component parts are plated to a thickness of 0.25 to
0.51 pjn (0.01 to 0.02 mil). The plating time is 3.55 minutes
with a current density of 1,350 A/m2 (125 A/ft2). Using the
above parameters and assuming reasonable production rates, wage
rates, and overhead, an estimared cost of 42 cents per faucet was
established. This value represents 0.67 percent, of the $62.67
list price for the faucet.
Using the above parameters, a reasonable estimate of the Ah
per part is 3.98. Given the model decorative plant parameters
from Chapter 5, the model plants are estimated to have the
following yearly potential outputs per plant: 753,258 faucets
for a small sized plant; 3,013,031 faucets for a medium sized
plant; and 30,130,314 faucets for a large sized plant. These
figures assume a current density of 1,350 A/m2 (125 A/ft2) .
Table 8-12 displays the estimated percent increase in
electroplating cost for the candidate control options, assuming a
baseline electroplating cost of $8.40/m2 ($0.78/ft2) (see
Appendix G, Section G.5). As displayed in Table 8-12, the
additional cost of chromium electroplating a single faucet could
be as much as 3.64 percent for a small model plant using a single
packed-bed scrubber. With sucn an increase in cost, substitution
away from chromium plating is unlikely to occur for two reasons.
First, most of the large plumbing fitting companies are full-line
suppliers with their own captive electroplating departments. As
a result, a firm would be more inclined to look at the effect on
the final price of faucets rather than on an intermediate
electroplating cost. Second, there is presently no low cost
8-38
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process with the corrosion resistant properties of hexavalent or
trivalent chromium plating. Further, without a significant
change in consumers' tastes for chromium plated faucets,
substitution away from chromium plating at the input stage is
unlikely to occur.
Even though the worst-case cost increase for chromium
electroplating a faucet could be 3.64 percent for the small model
plant under Control Option II, the impact on the final price
would be extremely small. Table 8-12 presents both the estimated
dollar amount and percent change in the final price. Control
Option II would increase the price of a kitchen faucet about
1 cents over the present cost of $62.65 or a 0.03 percent
increase (rounded up).
On the other hand, Control Option III, the use of permanent
chemical fume suppressants, would result in electroplating cost
increases of only 0.3 percent for a small plant and a product
price increase of l/10th of one cent. The impact of trivalent
chromium conversion is close to that of Control Option II.
8.2.4.2 Hand Tool_s. The hand tool market was selected
primarily to illustrate the economic impact of the control
options on a commonly used but relatively low priced product.
Most hand tools are sold in either the professional or the
do-it-yourself markets, and are sold at retail stores for less
than $25. (The final price is much lower than the other products
under investigation.) Also, unlike most other products selected
for analysis, hand tools are sold directly to consumers. The
hand tools analyzed are sockets, ratchets (socket wrenches), and
tape measures.
The surface area of one socket is about 72.3 cm2 (11.2
in.2) , The socket is chromium plated to a thickness of 0.15 jim
(0.006 mil). The plating time is 3 min at 2,150 A/m2 (200
A/ft2) . The cost of chromium electroplating a socket is
estimated at six cents per socket. Given this estimate, the
electroplating cost is 0.3 percent of the final price of $19.95.
The second hand tool selected for study was a 0.95 cm (3/8
8-40
-------
in.) ratchet. As sockets and ratchets are used together, adverse
effects on either one would clearly impact the other. Because
ratchets and sockets are often sold separately, however, they can
be analyzed as distinct products. The surface area of one
ratchet is 118.9 cm2 (18.43 in.2). The ratchet is chromium
plated to a thickness of 0.15 ^m (0.006 mil) . The plating time
is 3 minutes at 540 A/m2 (50 A/ft2) .
The estimated cost per ratchet of chromium electroplating
is ten cents. The electroplating cost is estimated as 2.7
percent assuming a final price of $3.69. The third hand tool
investigated is a tape measure. The product is the common steel
tape enclosed in a chromium plated ABS plastic case. The case
undergoes a two-stage chromium plating process in which it is
first etched and then decorative plated to a thickness of 0.26 |J.m
(0.01 mil). The surface area of the plastic case is 90 cm2 (14
in.2) . The plating time is 4 min. at 810 A/m2 (75 A/ft2) . The
manufacturers' estimated cost of chromium plating is 25 cents per
tape measure. Thus, the chromium plating of this product is
approximately 3.5 percent of the final price of $7.15, which is
higher than the plating costs for either the ratchet or the
socket.
Table 8-13 presents the parameters used to calculate annual
production rates for the three selected hand tools for the model
plants. The right-hand column of Table 8-13 displays the
calculated Ah per part for each of the selected products.
The potential output for each model plant was calculated by
dividing the production capacity (Ah/yr) by the Ah per part. The
production capacities of the model plants are displayed in
Chapter 5.
Table 8-14 summarizes the percent increases in
electroplating cost per unit of output for each of the selected
products under the control options. The numbers suggest that
there are some economies of scale for the larger model plants.
The lower percent increase in the electroplating cost for larger
model plants reflects the ability of these plants to process the
8-41
-------
TABLE 8-13. PARAMETRIC VALUES OF THREE HAND TOOLS
Hana tool
Socket
Ratchet
Tape Measure
Surface
area
on2
(in*)
8 (3)
64 (25)
36 (14)
Current
density
A/rn*
(A/ft2)
540 (50)
6!>0 (60)
810 (75)
Plating
time,
mm.
4
3
4
Ah
per part
0.0694
0.5208
0.4861
8-42
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8-43
-------
chromium emissions from two tanks through a single pollution
control device, thereby reducing a company's cost per tank.
In the case of the tape measure, the probability of
substituting away from hexavalent chromium plating appears likely
for two reasons. The increase in cost for Control Option II and
Control Option III ranges from 0.07 percent to 0.78 percent for
the small model plant. While this increase is not dramatic when
compared to the other hand tools analyzed, tape measure cases may
have a viable substitute in trivalent chromium (Control Option
IV). Under Scenario 2, for example, the use of trivalent
chromium would yield lower control costs. Also,, there are
suitable substitutes for chromium plating ABS plastic, for
example, painting and pigmentation.
The likelihood of eliminating chromium electroplating for
sockets and ratchets would appear to be very small for Control
Option III and moderate for Control Option II. Chromium plating
provides a much valued tarnish- and abrasive-resistant surface,
however, the estimated additional electroplating cost for sockets
would be more than four percent for the most costly Control
Option II for the small plant. As indicated by the small plant
data, trivalent control costs for ratchets vary from creating a
savings to being costlier than Control Option II and Control
Option III.
Table 8-14 also shows the estimated price changes for each
of the selected products (both percent change and dollar amount
of change). For sockets, ratchets, and tape measures, the
economic impacts associated with the control options range from a
slight savings to a maximum price increase of less than 3/10 of a
cent.
8.2.4.3 Automobile Parts. Domestically produced
automobiles are equipped with a wide variety of chromium plated
parts. Table 8-15 provides a list of most of the automobile
parts that typically- are either decorative or hard chromium
plated. To assess the economic impacts associated with the
control options, an estimate of the total additional cost from
8-44
-------
TABLE 8-15. LIST OF AUTOMOBILE PARTS TYPICALLY
CHROMIUM ELECROPLATEO
Decorative
Hard
Sumoer
Bumper Guards
Grilles
Grille Surrounds
Heaa Limo Bezels
3oor Hanoles
Siie view Mirror
Trun* L:CK Assemoly
I.itencr Coor Tnm
Racic
-------
all the chromium plated parts of a typical automobile must be
established.-
The first portion of this section presents a discussion of
the decorative plated parts, and the latter part focuses on the
hard chromium plated parts. The trend in recent years has been
to reduce or eliminate certain decorative chromium plated
automobile parts. There are several major factors simultaneously
influencing the substitution away from chromium plated parts.
The primary cause is the production of lighter cars in order to
comply with Federal fuel economy regulations and to satisfy
consumer demands for more fuel efficient automobiles. The weight
of steel used in the average new domestic car decreased from 966
kg (2,129 Ib) in 1978 to 793 kg (1,748 Ib) in 1988, an 18 percent
decline.33 Second, higher chromium electroplating pollution
control costs due to water pollution regulations have induced
producers to seek lower cost substitutes for chromium
electroplated parts where possible (e.g., urethane, rubber, and
paint). Also, the advent of superior substitutes for steel, such
as the heat, weather, and impact resistant arylon46, have
obviated the need for chromium electroplating.3< An additional
impetus for substitution is the damageability of steel and
aluminum parts, e.g., bumpers, during low impact accidents.
Finally, another explanation for the trend away from brightwork
may be a change in consumers' tastes toward the European or
Japanese style of black trim in place of chromium trim.
Six of the major chromium plated parts have been examined
in detail in an effort to document further this dramatic trend
away from chromium plated automotive parts. These parts include
bumpers, bumper guards, grilles, grille surrounds, head light
bezels, and door handles. The major source of data concerning
these parts is an extensive survey of external automotive trim
conducted by International Nickel, Inc.35 The survey is
conducted each year at the Annual Auto Show in Detroit, Michigan.
The information used in this section covers model years from 1980
to 1986.
8-46
-------
In 1980, 66 percent of all domestically produced
automobiles were equipped with chromium plated bumpers. By 1986,
the number of new models with chromium plated bumpers had been
reduced by 32 percent. The use of elastomeric bumpers
^elastomers are polymers possessing rubbery properties) has
increased by 141 percent during the seven years from 1980 to
1986. The movement away from chromium appears to be slowing down
with respect to passenger cars, while for recreational vehicles
the trend may have actually begun to reverse itself.
The trend away from chromium plated bumper guards is more
dramatic. In the last seven years, there has been a 65 percent
reduction in the number of new models sporting chromium plated
bumper guards. The elastomeric bumpers have done away with the
necessity of bumper guards. Over the last seven years, 68
percent of new passenger cars have eliminated bumper guards
altogether.
For grilles, chromium plated plastic remains the primary
choice of manufacturers. There has been a gradual movement
toward plastic coating. In 1986 a substantial number of new
models, perhaps as many as 10 percent, had no grilles at all.
While there is no clear trend, most grille surrounds are
either chromium plated or have been eliminated. The popularity
of brightwork reemerged as an important choice in 1986, when 44
percent of the new models had chromium plated surrounds as
opposed to 37 percent without any surrounds.
Two areas where chromium plated parts have maintained some
popularity are head lamp bezels and door handles. From 1980 to
1986, the survey shows that chromium plating has remained
dominant over either plastic or zinc as the metal coating of
choice. However, over the last seven years there has been a
slight trend away from chromium plating the bezels. Further,
approximately 23 percent of the 1986 models have removed the
bezel trim altogether.
Door handles have also experienced a movement away from
chromium plating. The alternatives to chromium are plastic and
8-47
-------
painted zinc. In 198Q/ 95 percent of the domestic models were
equipped with chromium plated door handles, and by 1986 the
number had dropped to about 70 percent.
To investigate the economic impacts associated with the
control options on domestic automobiles, one model was chosen for
an in-depth analysis. The largest selling domestically-produced
automobile for six consecutive years in the 1980s was the
Oldsmobile Cutlass/Ciera. In 1985, the Cutlass/Ciera accounted
for 51.7 percent of Oldsmobile's unit sales, 12 percent of
General Motors' unit sales, and 6.7 percent of total retail sales
of domestically produced automobiles. In each of the six years,
an average of 489,875 units of the Cutlass/Ciera was sold.36 The
Cutlass/Ciera usually is equipped with a wide variety of chromium
plated parts, including bumpers, bumper guards, grilles, grille
and rear window surrounds, head lamp and tail light bezels, hood
medallions, wheel covers, and door handles.
The total amount of decorative chromium plating is assumed
to be about 4.9 m2 (53 ft2), with approximately 2.4 m2 (26 ft2) of
the decorative chromium plated parts provided by the front and
rear bumpers. Information provided by Section 114 letters
indicate an average electroplating cost of $8.40/m2 ($0.78/ft2)
for all plated parts. Assuming this cost the automotive
decorative chromium plating may be as high as $42, or 0.46
percent of the total value of the car. The bumpers are plated by
large plants, while the other decorative parts are plated by
small and medium plants.
Table 8-16 presents the estimated percent change in
decorative electroplating cost for each of the control options,
assuming a baseline electroplating cost of $42 per automobile.
The changes- range from a cost: savings for Control Option IV,
Scenario 1 to a 1.84 percent increase for Control Option II
single packed-bed scrubber for the small model plant.
Table 8-16 also shows the estimated price changes for the
representative automobile (both percent change and dollar amount
of change). Control Option II, single packed-bed scrubber, would
8-48
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8-49
-------
increase the final price by 52 cents (0.007 percent of the final
price). These price changes will be combined in Table 8-18 with
the price changes associated with the control options for hard
chromium parts to assess the total effect on the retail price of
the automobile.
The parts of an automobile that typically are hard chromium
plated are listed on the right hand side of Table 8-15. As much
as 0.69 m2 (7.4 ft2) of total surface area is hard chromium
plated. The electroplating cost may be as high as $106 (1.6
cents/cm2 [10 cents/in.2]), or 1.2 percent, of the total retail
price of the automobile.
Applying the same methodology used for decorative chromium
automobile parts, Table 8-17 displays the percent increase in the
cost for the hard chromium plated parts under e>ach control
option. The ability of firms to substitute for hard chromium
plated parts is severely limited, even though electroplating cost
increases for Control Option El and Control Option III range from
5.55 percent to 9.43 percent for the small plant.
Table 8-17 also presents the estimated price increase for
hard chromium parts used in automobiles (both percent increase
and dollar amount of increase). Because chromium plated parts
constitute a small portion of the total cost of manufacturing an
automobile (i.e., less than two percent), the impact associated
with any of the control options on the final price is quite
small, i.e., generally less than 1/lOth of one percent.
Since automobiles contain both decorative and hard chromium
plated parts, the impact on final price must include the control
costs from both sources. Because both impacts were measured by
estimating the additional cost from separate processes, the total
additional cost attributable to chromium plating can be
calculated by combining the individual effects. Table 8-18 shows
the total estimated change in the final price of the automobile
for each of the control options. Various combinations of the
control options were paired to determine the total effect of the
control options for both hard and decorative automobile parts.
8-50
-------
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C Ul 4)
4J *-l"C
u oic
O. «J
—
1
^B
o c
w o
e -1-1
o o.
<_> a
O */* f*^l ^
a en uti en
a o — < —
a t/^ ^r 1 ^^
a >f> ui| "~
O — evil «
a ^ a u>t
O CO O (MJ
... .1
O Ul O CDI
O — CDI <->
0 — — 1 CM
O O Ol O
. • . t •
a a at a
a •*» w vo
O •" ( »
O CD ^^ 1 ^3
O C OJ T
o o — i c*
0 ^ «| "
o ^5 S| S
» • • * •
o — CMI rsi
a o -* — •«
o ^ **^ ^ l
C3 tf^ *^ ^^ 1
• • * • |
^3 ^^ ^O ^^ 1
W W
* •
*L "2.
•_ m zz
PHM ••• •>« Mii«
e
a
i-
^«
o
e
o
0
„,
e
o
H
o
^^
0
*^
e
o
4^
A^
^^
o
•i
V. ^
«J • «J
ja L. — .
J3 O
U, (O JS
0 C •*«
•a- c
OJ ^- «J
^3 ^^ ^v
^J V^ CL
0) & 3
*~* > *~
C irt >
— g ^
01
c e e
00 —
T3 •« ^1
a> ci u
w^ t^ ^3
ra >a c
en co 3
a _s
-------
TABLE 8-18. ESTIMATED CHANGE IN THE FINAL PRICE
PER AUTOMOBILE DUE TO THE VARIOUS CONTROL OPTIONS:
SUM OF BOTH HARD AND DECORATIVE CHROMIUM
PARTS FOR REPRESENTATIVE AUTOMOBILE
Control Opt1
decorative
k
I
II
III
II
III
IV-1
W-l
IV-2
IY-2
IV- 3
IV-3
on
nara
I
II
II
III
III
II
III
II
III
II
III
Percent
model
price
olant
small medium
0.00
0.07
0.07
0.10
0.10
NA
NA
NA
NA
NA
NA
0.00
0.02
0.02
0.03
0.03
NA
NA
NA
NA
NA
NA
change
size
large
0.00
0.01
0.01
0.02
0.02
(0.04)
(0.02)
0.01
0.02
0.01
0.02
Dollar
price
model
amount
chanqe
Of
olant size
small medium
0.00
6.30
5.91
8.69
8.30
NA
NA
NA
NA
NA
NA
0.00
1.77
1.58
2.76
2.57
NA
NA
NA
NA
NA
NA
large
0.00
0.99
0.98
1.56
1.55
(3.65)
(1.74)
1.01
1.58
1.12
1.69
8-52
-------
The combined, impact on the final price resulting from the most
stringent control options is estimated to be $8.69, or
approximately 0.10 percent of the final price. This estimate
applies to the small model plant size for decorative and hard
chromium plated parts under Control Option II and Control Option
III, respectively, both with single packed-bed scrubbers.
8.2.4.4 Industrial Rolls. The price of industrial rolls
can vary from a low of several hundred dollars to as much as
$20,000, with most rolls in the price range of about $5,000 to
$9,000. The cost of chromium electroplating industrial rolls is
largely a function of surface area (diameter x 7t x length) and
the thickness of the chromium to be deposited. Most industrial
rolls are chromium plated to a thickness of between 25 and 130 p.m
(1 and 5 mil), using a current density of approximately 0.31
A/cm2 (2 A/in.2) . Based on data obtained during emission
testing, the average surface area of an industrial roll is
approximately 6,500 cm2 (1,000 in.2). Table 8-19 shows this
information applied to an industrial roll with a surface area of
6, 500 cm2 (1, 000 in.2) .'
The electroplating cost as a percentage of the price of the
final product, in this case a capital good, may differ for rolls
with the same plating costs because of variations in roll
thickness (not plating thickness) prior to plating or in the
quality of the steel substrate. For most industrial rolls, the
cost of chromium electroplating is generally less than 10 percent
of the final price.
A more specific approach to estimating the electroplating
cost is to assume a cost factor per cm2 (in.2) . This cost factor
is the cost of chromium plating excluding any increase associated
with the control options. The cost factors used for the analysis
aAny reasonably sized roll (e.g., a roll from 3,200 to 51,6000
[500 to 8,000 in.2]) would serve equally well for purposes of
illustration because the plating time and, therefore, the Ah per
part can be approximated as a linear function of the surface area.
cm2
-------
TABLE 8-19. PARAMETRIC VALUES: INDUSTRIAL ROLLS
Plating Surface Current Plating
thickness area density - tlmt,, Ah
ym (mil) on2 (1n.2) A/m* (A/ft') mln. per part
25 (1) 6,500 (1.000) 3,100 (288) 108 3,600
1-30 (5) 6,500 (1,000) 3,100 (288) 540 18,000
6-54
-------
were 1 and 2 cents/cm2 (6 and 10 cents/in.2) for industrial rolls
plated to 25 ^im (1 mil) thickness, and 5 and 6 cents/cm2 (30 and
40 cents/in.2) for industrial rolls plated to 130 UJH (5 mil)
thickness. These cost factors were obtained from telephone
interviews with domestic manufacturers of industrial rolls and by
reviewing data obtained from information requested in Section 114
letters.
Table 8-20 presents the potential output of 6,500 cm2
(1,000 in.2) rolls plated to a thickness of 25 and 130 pm (1 and
5 mil) for the model plants based on the production capacity
(Ah/yr) of these plants. The small plant can produce 1,390 rolls
and the large plant can produce 44,440 rolls at a plating
thickness of 25 ^im (1 mil) . At a plating thickness of 130 |im (5
mil), small model plants can produce 280 rolls and the large
plants can produce 8,890 rolls. Table 8-21 presents the
potential electroplating cost for hard chromium plated rolls for
each size model plant under four distinct cost assumptions: 1, 2,
5, and 6 cents/cm2 (6, 10, 30, and 40 cents/in.2) .
Table 8-22 contains the estimated percentage increase in
the electroplating cost associated with the control options. The
percentage increase in the cost is inversely related to the
assumed hard chromium finish cost factor (i.e., higher cost
factors would have smaller percentage increases in cost due to
the compliance costs).
Even though the increase in the electroplating cost could
be as high as 13.79 percent for the small plant for the most
stringent control option, it is unlikely that substitution away
from hard chromium plating will occur for the majority of
industrial rolls. The newest potential substitute for hard
chromium plating is electroless nickel, but this process is not
satisfactory for most applications and is more expensive than
hard chromium plating.1' Moreover, the demand for industrial
rolls is a derived demand, that is, a firm purchases the roll as
an intermediate good to produce its own product. The demand for
rolls is derived from the profitability of selling the final
8-55
-------
TABLE 8-20. ANNUAL PLANT OUTPUT:
INDUSTRIAL. ROLLS*
Surface
area
cm2 (in. 2)
§,500
(1.000)
6,500
(1,000)
Plating
thickness
ym (ml 1 )
25 (1)
130 (5)
Plating
time,
mm.
108
540
Ah
per part
3,600
18,000
Model plant size
small meal urn large
(cutout of 6.500 crnz
[1,000 1n.z] rolls)
1,390 11,670 44,440
280 2,330 8,890
Production capacity 1s 5,000,000; 42,000,000; and 160,000,000 Ah/yr
for the small, meaium, and large model plants, respectively.
8-56
-------
TABLE 8
21 ESTIMATED ELECTROPLATING COST PER PLANT PER YEAR:
"' INDUSTRIAL ROLLS
meal urn large
0.01
(0.06)
0.02
(0.10)
0.05
(0.30)
0.06
(0.40)
6,500
(1.000)
6,500
(1,000)
6,500
(1,000)
5.500
(1,000)
60
100
200
400
25 (1)
25 (1)
120 (5)
120 (5)
83,000 700,000 2,667,000
139,000 1.167,000 4,444,000
84,000 699,000 2,667,000
112.000 932,000 3,556,000
-------
TABLE 8-22. ESTIMATED PERCENT CHANGE IN THE HARD CHROMIUM
ELECTROPLATING COST DUE TO THE VARIOUS CONTROL
OPTIONS: INDUSTRIAL ROLLS WITH DIFFERING COST FACTORS
Plating
Control thickness
Option ura (mil)
I 25
II 25
III*.c 25
III°'C 25
! 25
II 25
' i;ia-c 25
130
: 120
::a-c 130
::=-c no
130
II 130
IIIa'c" ' 130
:::°'c 120
(i)
(i)
(i)
(i)
(i)
(i)
(i)
(5)
(5)
(5)
(5)
(5)
(5)
(5)
(5)
Percent
cost at
small
0.000
8.040
13.790
11.397
Percent
cost at
smal l
0.000
4.824
8.274
6.838
Percent
cost at
smal 1
0.000
8.040
13.790
11.397
Percent
cost at
smal 1
0.000
6.030
10.343
8,548
Increase In electroplating
1 cent/cm* (6 cents/in. 2)
model plant
medium
size
large
0.000 0.000
2.124 1.261
3.457 2.055
47271 27357
increase 1n electroplating
2 cents/cm2 (10 cents/in. 2
model plant
size
medium large
0.000 0.000
1.260 0.757
2.076 1.233
27575 T7533
Increase in electroplating
5 cents/cm*1- ^30 cents/In.2
model olarit
medium
0.000
2.124
3.457
47273
increase in
6 cents/cm2
moael olant
meai urn
0.000
1.574
2.594
size
larae
0.000
1.261
2.055
27587
electroplating
(40 cents/in.2
size
large
0.000
0.946
1.541
)
}
)
aSasea en single packed-bee scrubber.
-Baseo en mesh-oad mist eliminator.
ClJnaerlined values represent least-cost
Opf.cn :*.I.
control option for Control
8-58
-------
good, for example, newspapers. In other words, the willingness
of a firm to pay for an additional unit of an intermediate good
can be thought of as the marginal revenue expected to result from
its use.37 Because the impact on the final goods associated with
the control options is very small, the incentive to search for
more economical substitutes is small.
8.2.4.5 Hydraulic Cylinders — Backhoes. Hydraulic
cylinders used in backhoes were selected for the economic impact
analysis because backhoes are widely used in the construction
industry and backhoe hydraulic cylinders are typical of hard
chromium plated cylinders classified in SIC Code 3531.
Table 8-23 presents a list of the hard chromium plated
cylinders found in a typical backhoe and the diameter, length,
and surface area of each cylinder that is chromium plated. Unit
prices for hydraulic cylinders range from $55 to hundreds of
dollars. A very common backhoe has a list price of a little more
than $37, 000.38
As with industrial rolls, the manufacturing cost of
chromium plating hydraulic cylinders is largely a function of the
surface area of the parts. The 11 hydraulic cylinders in a
typical backhoe are chromium plated to a thickness of 25 [im (I
mil). Approximately 8,160 Ah (at a current density of 3,100 A/m2
[288 A/ft2]) are needed to plate all 11 cylinders.
Table 8-24 shows the potential output for the model plants
producing chromium plated cylinders for an individual backhoe.
The large model plant could produce approximately 32 times the
output of the small model plant.
Through interviews with industry representatives, a
reasonable estimate of the cost of chromium plating the hydraulic
cylinders ranges from to I cent/cm2 (3 to 6 cents/in.2) . Table
8-25 provides the potential electroplating costs per each size
plant per year based on these cost factors.
Table 8-26 contains the estimated percent increase in
electroplating cost for the two different cost factors. The most
stringent Control Option (III, single packed bed scrubber) could
8-59
-------
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at
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-------
TABLE 8-24. OUTPUT PER PLANT PER YEAR
AT 80 PERCENT CAPACITY: BACKHOE CYLINDERS
Surface Plating Output of cylinders
area thickness Ah model plant size
cm2 (in.2) \m (mil) per part small meat urn large
14,600 (2,300) 25 (1) 8,160 620 5,150 19,610
-------
T«u e-
a«cnmAT,». COST:
Price per
Ctn2 (in.2)
0.005
(0.03)
0.01
(0.06)
Cost
per set of
Surface backhoe
area cylinders
on2 (1n.2) ($) small
14,600
(2,300)
14,600
(2,300)
68
136
»«» n»r plant ($)
moaei plant size
medium
arge
$42,200 $350,000 $1.333.000
$84,300 $700,000 $2.667,000
8-62
-------
TABLE 8-26. ESTIMATED PERCENT CHANGE IN THE COST OF
HARD CHROMIUM ELECTROPLATING
DUE TO THE VARIOUS CONTROL OPTIONS:
HYDRAULIC CYLINDERS FOR BACKHOES WITH
DIFFERING COST FACTORS
Control
Option
I
II
ma.c
Hjb.c
I
II
riIa.C
IIIb'c
Cost factor
$/cm2 ($/1n.2)
0.005 (0.03)
0.005 (0.03)
0.005 (0.03)
0.005 (0.03)
0.01 (0.06)
0.01 (0.05)
0.01 (0.06)
0.01 (0.06)
Percent
small
0.000
15.877 •
27.251
22.512
0.000
7.948
13.642
11.259
Increase in electrocuting cost
model olant size
medium
0.000
4.200
6.914
8.543
0.000
2.124
3^457
4.271
Urge
0.000
2.521
4.111
5.176
0.000
1.260
2.055
2.587
a5ased en single packed-bed scrubber.
^Sased on mesn-pad mist eliminator.
cUriaerl ined values represent least-cost control options for Control
Option III.
8-63
-------
increase the cost by about 28 percent.
Manufacturers have been attempting to discover a suitable
substitute for hexavalent chrome. Given the sizable potential
increases in the cost of manufacturing hard chromium plated
cylinders, the quest for a substitute for hexavalent chrome will
certainly continue, but, at this time, there is no close
substitute.
Table 8-27 provides estimates of the potential dollar and
percentage increases in the final price of the backhoe. Because
the only parts of a backhoe that are chromium plated are the
hydraulic cylinders, and the total dollar value of chromium
plated parts is small relative to the final price of the backhoe,
the impact of the control options on the final price would also
be quite small, i.e., less than 1/10 of one percent.
8.2.4.6 Analysis of Anodized Products
In order to assess the economic impact: of Control Option
IIs and Control Option IIIb on anodizing operations, several
products from the aviation industry (e.g., wing skins, jet engine
parts, housings, flanges, and miscellaneous aircraft parts) were
examined. These were the only chromium anodized products for
which Section 114 letters had complete process and cost
information. Anodizing operations fall into one of two
categories, small or large, defending on the chromic acid
consumed annually by the plant.
For large model plants, Table 8-28 shows that the anodizing
cost was estimated to increase by up to 0.72 percent for Control
Option II mesh-pad mist eliminator to 0.08 percent for Control
Option III. For small model plants, the estimated increase in
aSingle packed-bed scrubbers with annualized costs of $10,000
for small model plants and $25,800 for large model plants or mesh-
pad mist eliminators with annualized costs of $8,300 for small
model plants and $40,100 for large model plants.
bPermanent chemical fume suppressants with annualized costs of
$1,600 for small model plants and $4,600 for large model plants.
8-64
-------
TABLE 8-27. ESTIMATED DOLLAR (1988 $) AND PERCENT CHANGE IN THE
FINAL PRICE DUE TO THE VARIOUS CONTROL
OPTIONS: BACKHOES
Dollar orlce increase
Control
Option
I
II
ma,c
Hlb.c
moa el
small
0.00
10.93
18.76
15.50
olant
medium
0.00
2.85
iili
5.82
size
large
0.00
1.71
2.80
3.53
Percent orlce increase
moeei
small
0.000
0.031
0.054
0.045
plant size
meaiurn
0.000
0.009
0.013
0.016
large
0.000
0.006
0^08
0.010
aSased on single packeo-bea scruober.
DSasea on mesn-paa mist eliminator.
Cllnaerl1ned values represent least cost control options for Control
Option III.
8-6!
-------
TABLE 8-28. ESTIMATED PERCENT CHANGE IN THE COST
OF CHROMIC ACID ANODIZING DUE TO
THE VARIOUS CONTROL OPTIONS
Percent Increase 1n
Control Cost; anodizing cost
Anodizing cost Small Large: model plant size"
Small Large ($) ($) Control Option Small Large
144,000 5,550,000 10,100 25,800 II 7.0 0.46
Single packed-
bed scrubber
144,000 5,550,000 8,300 40,100 Mesh-pad mist 5.8 0.7
eliminator
144,000 5,550,000 1,600 4,600 III 1.1 0.08
Permanent chem-
ical fume sup-
pressant
8-66
-------
anodizing cost for a mesh-pad mist eliminator was approximately
5.8 percent for Control Option II and 1.1 percent for Control
Option III. Although the large model plants are approximately 10
times larger in capacity than the small model plants, the small
plants have higher percent increases in anodizing costs. This is
because the annualized cost of the control option is only
approximately three times greater for the large model plants than
for the small model plants.
The impacts on the price of final products containing
anodized products are expected to be negligible because the
anodized products constitute such a small percentage of the price
of the final airplane product and an even smaller percentage of
the price of a trip.
On the other hand, the price increase at the intermediate
stage of anodizing could be large enough to cause small plant
owners to explore the substitution of chromic acid anodizing with
sulfuric acid anodizing.
8.2.5 Quantity and Revenue Effects
To estimate the impacts associated with the control options
on quantity and revenue, the concept of price elasticity of
demand was applied to the five electroplated products. Price
elasticity is defined as the percentage change in the quantity
demanded divided by the percentage change in price. Goods with a
price elasticity of demand that is greater than -1.0 are
insensitive to price change and have increases in revenue as a
result of a given price increase. Goods with price elasticities
less than -1.0 are sensitive to price change and have decreases
in revenue as a result of increases in price.
The estimated effect on revenue was derived from the
following equation:
%AR = %AP (1 + E)
8-67
-------
where,
%AR = percentage change in revenue
%AP = percentage change in price.
E = price elasticity
Table 8-28 displays the estimates of the percentage changes in
price, quantity, and revenue for the selected products. The
percentage change in price used in this section was drawn from
the largest price change of each of the selected products in
Section 8.2.4. The largest price change was typically associated
with the most costly control option for the small model plant.
Because the analysis in Section 8.2.4 did not present estimates
of price elasticity for each of the selected products, price
elasticities ranging from -0.01 to -1.2 were assumed.
The first four products listed in Table 8-29 (i.e.,
faucets, sockets, ratchets, and tape measures) are usually final
products that are not capital goods. These products are all
composed of decorative chromium. The remaining four products
(i.e., decorative chromium automobile parts, hard chromium
automobile parts, industrial rolls, and hydraulic cylinders used
in backhoes) are considered either intermediate products or
capital goods.
As the costs of the capital goods and intermediate products
surveyed for this study represent only a fraction of the cost of
the final products to which they contribute, the derived demand
for these goods and products should be highly inelastic, i.e.,
greater than -0.25.39 Consequently, in such cases,
electroplating firms are likely to be able to pass on a cost
increase without affecting the quantity of electroplating
demanded.
The data presented in Table 8-29 supports this assumption.
As shown in this table, the price elasticities for the first four
products generally range from -0.25 to -1.2, whereas the price
elasticities for the remaining four products generally range from
8-68
-------
TABLE 8-29. ESTIMATED PERCENT CHANGES IN QUANTITY AND REVENUE
FOR EACH OF THE PRODUCTS SELECTED FOR ANALYSIS •**
Assumed size of elasticity
Type of Plate/
Product/change -0.01
DECORATIVE CHROMIUM
FAUCETS
Price Change (%)
Quantity Change (%)
Revenue Change (%)
SOCKETS
Price Change (%)
Quantity Change (%)
Revenue Change (%)
RATCHETS
Price Change (%)
Quantity Change (%)
Revenue Change (%)
TAPE MEASURES
Price Change (%)
Quantity Change (%)
Revenue Change (%)
AUTO DECORATIVE
Price Change (%) 0.065
Quantity Change (%) -0.001
Revenue Change (%) 0.064
HARD CHROMIUM
AUTO HARD
Price Change (%) 0.111
Quantity Change (%) -0.001
Revenue Change (%) 0.1 10
INDUSTRIAL ROLLS
Price Change (%) 0.820
Quantity Change (%) -" -0.008
Revenue Change (%) 0.812
BACKHOES
Price Change (%) 0.054
Quantity Change (%} -0.001
Revenue Change (%) 0.053
-0.10 -0.25 -0.50
0.024 0.024
-0.006 -0.012
0.018 0.012
0.015 0.015
-0.004 -0.008
0.01 1 0.008
0.033 0.033
-0.008 -0.017
0.025 0.017
0.026 0.026
-0.007 -0.013
0.020 0.013
0.065 0.065
-0.007 -0.016
0.059 0.049
0.111 0.111
-0.01 1 -0.028
0.100 0.083
0.820 0.820
-0.082 -0.205
0.738 0.615
0.054 0.054
-0.005 -0.014
0.049 0.041
-0.75 -1.00 -1.20
0.024 0.024 0.024
-0.018 -0.024 -0.029
0.006 0.000 -0.005
0.015 0.015 0.015
-0.011 -0.015 -0.018
0.004 0.000 -0.003
0.033 0.033 0.033
-0.025 -0.033 -0.040
0.008 0.000 -0.007
0.026 0.026 0.026
-0.020 -0.026 -0.031
0.007 0.000 -0.005
- To determine the percent change in price industrial rolls, an initial price of $5,000 per industrial roll is used.
b Price changes used in thisiaWe-are-fdr highest cost eoTiFrel-Gptfori-for-model-plant size with htghesT-eostSr-
- Only the most applicable elasticity coefficients were used to calculate the percentage changes in the table.
8-69
-------
-0.01 to -0.25. This indicates that the latter four products'
demands are relatively inelastic compared to those of the first
four products. However, as the percentage price changes for the
first five products are much less than those for the remaining
three products, the revenue effects with respect to all eight
products studied are very small. The revenue changes range from
0.110 percent to -0.005 percent for final goods, including those
final goods associated with the intermediate products and capital
goods studied.
8.2.6 Total Industry Impacts
See Chapter 7 "Cost Analysis of Control Options" for
details of the derivation of total costs.
Nationwide annualized costs for chromium emissions control
are separated into three categories: decorative plating sources,
hard plating and anodizing.
For decorative plating the annualized costs are as follows:
Millions
Control Option II, single packed bed scrubber $12.30
Control Option II, mesh pad mist eliminator 11.45
Control Option III, chemical fume suppressants 6.04
Control Option IV, trivalent chromium
Scenario 1 (254.41)
Scenario 2 (10.43)
Scenario 3 55.87
For hard chromium plating, the annualized costs are as
follows:
Control Option II, Chevron blade mist eliminator $16.83
Control Option III, single packed bed scrubbers 23.22
Control Option III, mesh-pad mist eliminators 24.27
For anodizing the annualized costs are as follows:
Control Option II, single packed-bed scrubbers $7.16
Control Option II, mesh-pad mist eliminators 7.87
8-70
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Control Option III, chemical fume suppressants 1.53
The most costly combination of controls would total $88.0
million: decorative, Control Option IV-3 ($55.86); hard, Control
Option III, mesh-pad mist eliminator ($24.27); and anodizing,
Control Option II, mesh-pad mist eliminator ($7.87) .
It should be noted that the above annualized expenditures
data for Control Option I (the baseline) shows costs greater than
zero whereas the model plant analysis tables for each product
presented earlier in the chapter shows zero costs. The
explanation is that the above greater than zero aggregate costs
for Control Option I represent incremental costs for the small
portion of operations that are presently uncontrolled (25 percent
of the hard chromium electroplating operations and 15 percent of
the decorative operations). The earlier model plant analysis
designates Control Option I as the most prevalent baseline
control situation in the industry which is that the majority of
operations have scrubbers, mist eliminators or fume suppressants.
Therefore the incremental cost for achieving Control Option I is
zero .
8.2.7 Small Business Impacts
Section 8.2.4 demonstrates that the control costs
associated with the various control options would be several
times larger for hard chromium electroplaters than for decorative
platers. Thus, if small businesses are going to be
differentially impacted, the effects would more readily be found
in hard plating operations. In addition, the average
electroplating job shop is a small business with annual sales in
1986 of $1,134,900. Estimates indicate there are presently 885
hard chromium job shops in the U.S.13
The Small Business Administration (SBA) defines SIC 3471,
job shops, by an employee size of 500 or less. Number of
employees is not always a good criterion for designating small
business for this analysis, because electroplating and anodizing
are processes and most reported data on number of employees
8-71
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includes people from other manufacturing processes. In addition,
many large capacity operations are automated and only require a
small number of employees. As shown in Table 8-4, 1635 of the
2159 firms, or 75.7 percent, in the Products Finishing list had
500 employees or less. The level of 500 employees is used herein
as the definition of a small business.
The small size model plant in this report has a 5,000,000
Ah capacity. For hard chromium electroplating operations, which
will be the focus of the small business impacts analysis, 1,170
(or 76 percent) of the 1,540 chromium electroplating operations
fit the small model plant category. This means there is a high
likelihood that a small hard chrome electroplating plant will
also be a small business.
The Regulatory Flexibility Act (RFA) requires that special
consideration be given to the impacts of all proposed regulations
affecting small businesses. As just shown, there is a
substantial number of small businesses performing hard chromium
electroplating, many of which are job shops. The EPA has issued
RFA guidelines containing the following criteria for use in
determining what is a "significant adverse economic impact" and
what would therefore require the performance of a Regulatory
Flexibility Analysis.
o Annualized compliance cost increases total cost of
production by more than 5 percent.
o Compliance costs as a percentage of sales for small plants
are at least 10 percentage points higher than for large
plants.
o Capital costs of compliance represent a significant portion
of capital available to small entities, where
available
capital is measured by pretax cash flow minus annual
capital expenditures.
o The requirements of the regulation are likely to result in
closures of small entities.
8-72
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The impacts associated with the control options will have a
negligible effect on the price of any final good, as shown in
Section 8.2.6. Clearly, the cost of the hard chromium components
of a final good (e.g., industrial rolls) is insignificant
relative to the cost of other materials involved in the
manufacture and distribution of the final good. Thus, the first
criterion listed above for significant impacts is not satisfied.
Table 8-30 presents control costs as a percent of net sales
for the three sizes of model plants. The control costs used to
calculate these figures are from Table 8-11. Net sales figures
are derived form the RMA Annual Statement Studies 1991. Table 8-
30 indicates that control costs as a percentage of net sales for
a small model plant are not ten percentage points higher than for
large model plants for any control option. The greatest
differential that could occur would be 1.7 percentage points if
the single packed bed scrubber control option is implemented.
There are two ways in which capital availability arises as
an issue (third criterion). The first concern is the ability of
small decorative plants to raise capital to make a conversion to
trivalent electroplating that in some instances will save annual
costs. Decorative chromium ; laters have the option of converting
to trivalent electroplating (Control Option IV), whereas hard
chromium platers do not have this ability. However, the
conversion requires more capital for decorative platers than the
installation of add-on controls such as for Control Option II.
The second question arises as to whether capital can be obtained
to finance the other add-on controls at hard or decorative plated
shops.
Table 8-31 was constructed from financial data reported by
Robert Morris Associates for the electroplating industry.40 A
small firm with annual sales of $500,000 was selected. This size
firm is at the lower end of the range of small firms. The table
shows how profits before taxes would be impacted by the various
costs of controls and also shows how several financial ratios for
the firm would be affected by the RAs. These ratios are used by
lenders to determine whether to loan money. (Outside financing
8-73
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TABLE 8-30. HARD CHROMIUM ELECTROPLATING CONTROL COST AS
PERCENT OF SALES FOR SMALL, MEDIUM AND LARGE
MODEL PLANTS
Model plant size
Control option small medium large
II
Chevron blade mist eliminator (double)
Control Costs $ 6,700 $ 14,700 $ 33,600
Sales $600,476 $3,650,496 $28,118,286
Control Costs Divided by Sales (%) 1.1 0.4 0.1
III
Single packed-bed scrubber
Control Costs $ 11,500 $ 24,200 $ 54,800
Sales $600,476 $3,650,496 $28,118,286
Control Costs Divided by Sales (%) 1.9 0.7 0.2
Mesh-pad mist eliminator
Control Costs $ 9,500 $ 29,900 $ 69,000
Sales $600,476 $3,650,496 $28,118,286
Control Costs Divided by Sale:s ('/.) 1.6 0.8 0.2
8-74
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TABLE 8-31. CAPITAL AVAILABILITY ANALYSIS FOR
SHALL CHROMIUM ELECTROPLATING FIRM
Sales
Profit Before Taxes without controls
(93.6% of sales)
Profits After Taxes (3.01 of Sales)
»
Profit Before Taxes with Controls
Chevron blade mist eliminator
Single packed-bed scrubber
Mesh-pad mist eliminator
Fume Suppresant
TMvalent Chromium
Scenario 1
Scenario 2
Scenario 3
Depreciation (4.2% oi sales)
Cash Flow (Profits i Oepr.)
Current Maturities tong-Term Debt (CMLTD)
Total Assets (Sales/Assets « 2.571
Total Debt (56.9% of Assets
Net Worth (43.1% of Assets)
Current Assets (60.8% of assets)
Current Liabilities (CA:CL»1.8)
Interest
Capital
AnnuaHzed Cost
5 6,700
11.500
9,500
1,000
23,500
(11,000)
13,200
Debt:
Outlays Net Worth CA:CL
Baseline Ratio
New Ratios
Single packed-bed $ 45,900
scrubber
Mesn-pad mist- 28,900
eliminator
Chevron blade mist 29,800
eliminator
Trivalent Scenarios 1 66,900
2
3
1.32 1.80
1.87 1.S7
1.67 1.65
1.68 1.65
2.13 1.50
2.13 1.50
2.13 1.50
$500,000
18,000
15,000
11,300
6,500
8,500
17,000
Negative
29.000
4,800
21,000
36,000
17,143
194,500
110,865
83,635
118,256
65,698
13,304
E3IT CFrCMLTO
2.35 2.10
1.45 1.15
1.60 1.32
1.76 1.43
0.83 0.71
2.55 1.76
1.33 1.01
8-75
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would be needed by many small chromium electroplating firms
because the profits before taxes plus the depreciation cash flow
would generally be insufficient to pay for most sets of
controls.) As Table 8-31 shows, the debt-to-net-worth ratio
increases substantially for a firm of this size under all add-on
and trivalent control alternatives. The ratio is 1.32 before
controls and anywhere from 1.67 to 2.13 with controls. Ratios
above 1.0 are considered high to begin with and ratios above 1.5
are very high. The ratio is highest for trivalent chromium.
The current ratio (i.e. current assets divided by current
liabilities) is 1.8 before controls and reduces to between 1.5
and 1.65 after controls. This ratio is less affected because the
assumption was made herein that the controls are financed by
long-term debt. The reduction in the ratio is due to the current
portion of the long-term debt being carried as a current
liability. The performance of this ratio would not deter firms
from obtaining financing for control systems.
Cash flow over current maturities of long-term debt (CF:
CMLTD) is a ratio that lenders examine to determine the assurance
that cash flow will be sufficient to repay debt principal. The
small size firm's baseline ratio is 2.1. A similar ratio is
earnings before interest and taxes (EBIT) over interest (baseline
2.35) . Lenders look to this ratio to evaluate the adequacy of a
company's earnings to cover interest payments.
The baseline CF: CMLTD ratio drops from 2.1 to between 0.7
and 1.76. A ratio below 1.2 is considered insufficient. Two of
the three trivalent chromium scenarios produce insufficient
ratios. The SPBS also produces an insufficient ratio. The EBIT
ratio changes from 2.35 to 0.8 to 2.6. For the same
insufficiency Jlevel for this ratio the same control systems
produce insufficient ratios as for CF:CMLTD.
In conclusion, some of these very small firms aren't likely
to be granted capital for add-on controls particularly for SPBSs .
For conversions to trivalent chromium the ability for these very
small firms to obtain capital will depend upon their reject rate
8-76
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and its effect on annualized control costs.
It should be remembered that the above static analysis is
performed with statistics that have a great deal of variability
within them. The performance of firms varies from year-to-year
and a certain number of firms enter or leave the business each
year causing the data to change along with effects from business
cycles. The analysis above used median data for the financial
ratios. As an example of the variation, although the median for
the debt worth ratio was 1.3 the values for the 25th and 75th
percentiles were 2.8 and 0.5. Still using 1.5 as the ratio of
acceptability for lenders, the variation in data for this ratio
shows that over 25 percent of all firms start off with a ratio
unacceptable to lenders. Some of these firms may be already
headed for business closure or some may be in temporary
difficulty where an infusion of equity capital may be planned.
Likewise for the ratio cash flow to current maturities of
long-term debt the median is 2.1 while the other two quartiles
are 1.7 and 5.6
For firms with sales above $500,000 the capital
availability ratios quickly begin to improve. Only a few firms
with sales above $500,000 are likely to face capital availability
problems.
Closure potential (the fourth criterion) ties in directly
with the availability of capital (the third criterion) and the
impact of differential control costs. As Table 8-30 showed, a
differential control cost exists between the small and medium
hard chromium plating model plants, and between the small and
large hard chromium plating model plants. Furthermore, many
small hard chromium job shops would experience even larger
differential cost impacts because they operate their tanks at
lower capacity utilization rates than medium and large size model
plants. Plants operating at low utilization rates would incur
the same annualized capital costs as plants operating at high
percentages of production capacity, causing higher per unit
output control costs.
8-77
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Because the large and medium plants have more discretion
over price than the small plants, small plants that do not have
their own market niche will bear a portion of the control cost
differential in the form of re:duced profitability. Table 8-30
showed that the small plants may only be able to pass on 10 to 20
percent of the control costs in the form of higher prices,
because the industry price will be established by the more
efficient firms.
The concern is whether the control cost that cannot be
passed on to consumers by small hard chromium plants would be
significant enough to cause closures. A limited survey of job
shops revealed that the majority of small job shops compete
vigorously with large job shops for hard chromium plating.41
Thus, it cannot be claimed that all small plants have their own
market niche and can pass these differential costs on to their
customers. On the other hand, it was revealed that competition
is based more on quality of service and delivery time than it is
on price. For small plants that have their own market niche,
some or all of the differential is likely to be passed on as
price increases due to the competitive -advantage of the plants.
On balance, however, it is likely that many small plants will
have to absorb some compliance costs, causing profits to
decrease. Whether or not the profit decrease would cause small
plant closure requires an analysis of existing profit rates, cash
flows, and net present values of small firms before and after
effects associated with the control options.
Two approaches were used to estimate this closure potential
for small plants. In the first approach, a formula was used
whereby the net present value (NPV) of the plant could be
estimated with_.and without the control costs of the control
option. Allowing for chromium electroplating operations to earn
their cost of capital, the decision to close occurs when the
control cost causes a plant' s NPV to go from positive to
negative.
The formula is:
8-78
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20
NPV = I r(1-.4) (E3Tt-CCt)1 + .8(WC) + .2(FA)
t = l (l + r)t (1 + r)20 (1 + r)20
where,
CC = Annual control costs absorbed by the hard
chromium
plating operations
EBT = Earnings before taxes chromium plating operations
WC = Working capital
FA = Fixed assets
r = Cost of capital
.4 = Combined federal, state, and local corporate
income
tax rate.
The assumptions inherent in the above formula are:
o Depreciation cash flows of the operation will be used
for sustaining capital expenditures
o 80 percent of the operation's working capital value
will be recovered at the end of 20 years
o 20 percent of the operation's fixed asset value will
be recovered at the end of 20 years
o The cost of capital is 10 percent. This assumption is
consistent with the discount rate used in Chapter 7.
This formula is particularly sensitive to the level of
control costs absorbed. As shown earlier in this section, the
small plants should be able to recover approximately 10 to 20
percent of the control costs through the price increases of the
larger job shop price leaders.
Because there are so many operations with controls already
in place, thus threatening potential price increases, the NPV
8-79
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calculations were made with and without some control costs being
passed on.
Ninety-one companies with $1 million or less in assets in
SIC codes 3471 and 3479 reported median earnings before tax
profit rates (EBT) on sales of 3.6 percent for these companies'
fiscal year 1989. For the same companies, the median sales to
working capital (WC) ratio was 13.6 and the median sales to net
fixed asset (FA) ratio was 7.1.40
The NPV calculations revealed that firms of $245,000 sales
or less which could not pass on any control costs under Control
Option III would close. For plants which could pass on one-tenth
of their control costs, the closure point was about $220,000 in
sales.
There are about 116 hard chromium job operations with sales
less than $500,000.n The number of operations with sales of
$220,000 or less is 51 assuming proportional representation.
Because 70 percent of the small hard chromium operations already
have packed-bed scrubbers (Control Option III) or Chevron blade
mist eliminators (Control Option II), the number of plants likely
to close is 0.3 x 51 or about 15 plants.
The 70 percent of already-controlled plants includes plants
with Chevron blade mist eliminators. In reality if Control
Option III is selected these plants will also incur'incremental
control expenditures. For example for the small hard chromium
plant the incremental annualized cost is $2800 (see Table 8-11)
which is enough to cause closure for plants of $70,000 or less
assuming a pass forward of one-tenth of the control costs. The
number of plants affected would be 5 (0.3 x 16 plants) . These 20
plants constitute approximately 1.7 percent of the total of 1,170
small hard chromium job operations.
The estimate of 20 total closures under Control Option III
is likely a worst-case estimate for three reasons. First, the
above calculations assume that all plant sales are attributable
to direct electroplating only, and exclude sales revenue of
ancillary operations such as polishing, grinding, etc. Because
8-80
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revenue and earnings before taxes would, in reality, be higher
than revenues exclusively from the electroplating process, the
above estimate represents an upper limit. The second reason is
that some small firms have their own market niche and will be
able to pass on the differential control costs. The third reason
is that even though the number of electroplating plants is
depicted herein as being stable over the next five years, there
is a trend toward large operations as opposed to smaller
operations. An unknown percentage of small operations would be
expected to cease operations for economic reasons over the impact
time frame, some of them possibly overlapping with the above
estimated closures. Fourth, this estimate only applies for the
most costly Control Option III, for hard chrome electroplating.
An alternative method to determine the number of potential
plant closures can be performed based on the data presented in
Table 8-32. This data shows that the bulk of the industry
capacity is provided by large operations. As a result, large
operations will most influence the price for hard chromium
products and so will be able to pass on their increased costs to
the consumer. However, the smaller operations will be less able
to pass on their full cost increases. It is, therefore, assumed
that closures will occur only in the smaller, less efficient
operations. The number of closures would equate to the reduction
in industry output expressed in Ah, divided by the average Ah
capacity of the small model plant.
Table 8-33 presents a range of percent price increases
compared against two elasticity values (i.e., -0.05 and -0.15)
that represent the derived demand for hard chromium plated
products. The numbers in the center of the matrix indicate the
number of plant closures for each percent price increase and
elasticity value combination for Control Option III. The most
likely percent price increase would be a weighted average percent
price increase based on a plating cost of 40 cents per square
inch, plated to a thickness of 0.005 inches and calculated as
-------
TABLE 8-32. NUMBER OF PLANTS, PLANT SIZE, INDUSTRY CAPACITY,
AND PERCENT OF INDUSTRY CAPACITY — HARD CHROMIUM ELECTROPLATERS
Model
plant
size
Number
of plants
Ah
Industry capacity
(Ah)
Percent
of Industry
capacity
Small
Medium
Large
1,080
310
150
5,000,000
42,000,000
160,000,000
5,400,000,000
13,020,000,000
24,000,000,000
12.73
30.69
56.58
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TABLE 8-33. NUMBER OF SMALL PLANT CLOSURES BASED ON PERCENT
PRICE INCREASE AND ELASTICITY VALUE COMPARISONS
Elasticities
Percent
price Increase -0.05 -0.15
0.25 1 3
0.50 2 6
0.75 3 10
1.00 4 13
1.15 5 15
1.50 6 19
8-83
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follows:
3
W = E (Mi Pi) . NC
where:
W = Weighted average percent price increase
M = Market share for each model plant size
P = Percent price increase for each model plant size
i = Small, medium and large size plants
NC = Percent noncompliance in industry (.30 percent)
The value of such a weighted average percent price increase
is 1.12 percent and is comprised of 0.83 percent for those
without controls and .29 for those with Control Option II.
Next the number of closures was estimated using the
following formula:
N = (W * E * 0)/S
where
N = Number of closures
W = Weighted average percent price increase/100
E = Price elasticity
0 = Industry wide capacity for hard chromium electroplaters
S = Ampere hours of capacity for a small model plant
Thus a percentage price increase of 1.12 and a price elasticity
of -.15, coupled with an industry wide capacity of 42,420,000,000
Ah and an Ah capacity of 5,000,000 for a small model plant would
produce an estimated fourteen closures.
Based on the two closure analyses presented above, this
report assumes that 14 to 20 plant closures will potentially
8-84
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occur as a result of the most stringent Control Option III. The
capital availability analysis performed earlier suggests that
those who close are likely to be those who have difficulty
raising capital.
In summary, none of the four economic impact criteria
examined for small business impacts are triggered by the control
options. The price increases and control costs as a percent of
sales do not produce significant impacts on small firms. Capital
availability difficulties discussed earlier will be felt by the
smallest of the small firms but not a substantial number of all
small entities. The 14 to 20 plant closures estimated are also
not a substantial portion of the total number of small hard
chromium electroplating plants.
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8.3 REFERENCES FOR CHAPTER 8
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14. Chromium Plating: Operations Crosshatch by SIC and
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28. Iron Age Data Bank Market Guide. Radnor, PA, Chilton
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41. Telephone survey conducted by Donate, S.A., JACA Corp.,
to contacts at the following companies: Accurate
Electroplating (Philadelphia, Pennsylvania), Armolog
Company (Croydon, Pennsylvania), Easton Plating and
Metal Finishing (Easton, Pennsylvania), Frankford
Plating (Philadelphia, Pennsylvania), and Garnet
Chemical (Allentown, Pennsylvania). April 30 - May 1,
1987. Information about small job shop operations.
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