PB  198  348

SYSTEMS ANALYSIS  OF  EMISSIONS AND EMISSIONS  CONTROL IN THE IRON
FOUNDRY INDUSTRY.   VOLUME I.   TEXT

A. T.  Kearney  and Company
Chicago,  Illinois

February 1971
                  NATIONAL TECHNICAL INFORMATION SERVICE
                                                            Distributed , , .'to foster, serve and promote the
                                                                         nation's economic development
                                                                         and technological advancement.'
                                                                      U.S. DEPARTMENT OF COMMERCE
                               This document has been approved for public release and sale.

-------
                                                PB  198  348
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                          NATIONAL TECHNICAL
                          INFORMATION SERVICE
                                  V«. 23151
                                                                                                                SYSTEMS ANALYSIS OF EMISSIONS
                                                                                                                AND EMISSIONS CONTROL IN THE
                                                                                                                   IRON FOUNDRY INDUSTRY
                                                                                                                      VOLUME I TEXT
                                                                                                                      FEBRUARY, 1971
                                                                                                                           For
                                                                                                           Division of Process Control Engineering
                                                                                                                Air Pollution Control Office
                                                                                                               Environmental Protection Agency
                                                                                                                 Contract No. CPA 22-69-106
                                                                                                                      Prepared by
                                                                                                             A. T. Kearney & Company, Inc.
                                                                                                                   Chicago, Illinois

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          AIR POLLUTION CONTROL OFFICE
   SYSTEMS ANALYSIS OF EMISSIONS AND EMISSIONS
       CONTROL  IN THE IRON FOUNDRY INDUSTRY
                 VOLUME I TEXT
                 FEBRUARY.  1971	
II
    TABLE OF CONTENTS


INTRODUCTION
  Acknowledgements
  Purpose of the Study
  Scope of the Study
  Literature Search and Bibliography
  Glossary of Terms
SUMMARY AND RECOMMENDATIONS
  Scope and Objectives
  Description of the Iron Foundry
    Industry
  Emissions Produced and Control
    Capability
  Quantification and Evaluation of
    Emissions
             Projection of Trends
             Definition of Iron Foundry Air
               Pollution Problems
             Recommended Research & Development
                                                        PAGE
                                                         I  -  1
                                                         I  -  1
                                                         1-2
                                                        II -  1
                                                        II -  1
                                                        II -  3
                                                        II -  4
             Technical Analysis of Control Technology   II -  6
             Economic Analysis of Control Equipment     II -  6
             Potential Modifications to Foundry
               Practices and Emissions Producing
               and Control Equipment
                                             II - 8
                                             II - 10

                                             II - 13
                                             II - 14
                                                                                                                                 2  -

                                                                                                                                    PAGE
                                                                            IV
AIR POLLUTION AND THE IRON FOUNDRY
  INDUSTRY
  Description of the Iron Foundry
    Industry
      Iron Castings Production
      Iron Foundry Population
      Geographical Location  of  Iron
        Foundries
      Iron Foundry Melting Equipment
      Other Equipment in  Iron Foundries
  Basic Characteristics of the  Iron
    Foundry Industry
      Compilation of  Foundry Data
      In-Plant  Foundry Visits
  The Air  Pollution Problem

 DESCRIPTION OF  BASIC  FOUNDRY PROCESSES
   Introduction
   Process  Flow  for Gray,  Ductile and
    Malleable Iron
   Process  Flow  and Descriptions of Basic
     Foundry Operations
       Raw Material Storage and Furnace
         Charge  Preparation
           Raw Material  Receiving and
             Storage
           Scrap Preparation
           Furnace Charge Preparation
III - 1
III - 1
III - 2

III - 3
III - 4
III - 9

III - 11
III - 11
III - 12
III - 13


  IV  -  1

  IV  -  2

  IV  -  3
  IV  -  3

  IV  -  3
  IV  -  4
  IV -  5

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                                                       - 3 -
                                                                                                                                              -  4 -
SECTION
                  Iron Melcing
                     Cupola  Furnaces
                     Electric  Arc  Furnace
                     Induction Furnaces
                     Reverberatory Furnace
                  Inoculation
                     Ductile Iron  Production
                     Improvement of Mechanical
                      Properties
                  Duplexing
                  Molding, Pouring, Cooling and
                    Shakeout
                      Green  Sand Molding
                      Centrifugal  Casting
                      Dry Sand Molding
                      Shell  and Hot Box Molding
                      Full Mold Process
                      Rheinstahl Process
                      Pouring  and  Cooling
                      Shakeout
                  Sand Conditioning
                      Receiving and Storage
                      Sand Preparation
                      Sand Reclamation
 PAGE
 IV - 6
 IV - 7
 IV - 15
 IV - 19
 IV - 23
 IV - 23
 IV - 24

 IV - 24
 IV - 25

 IV - 25
 IV - 26
 IV - 27
 IV - 27
 IV - 28
 IV - 29
IV - 29
IV - 29
IV - 30
IV - 30
IV - 31
IV - 31
IV - 33
SECTION                                                    PAGE
                  Cleaning, Heat Treating  and
                    Finishing                               IV -  33
                      Cooling and Sorting                   IV -  34
                      Castings Cleaning                     IV -  34
                      Heat Treating                         IV -  36
                      Casting Finishing                     IV -  36
                      Casting Coating                      IV -  37
                  Coremaking                                IV -  37
                      Core Processes                        IV -  37
                      Core Department Process  Flow         IV -  40
                  Pattern Making                            IV -  42

    V       EMISSIONS PRODUCED AND EMISSION CONTROL
              CAPABILITY
              Emissions Produced  in  the  Basic  Processes     V -  1
                Raw Material Storage  and Charge
                  Makeup                                     V -  1
                Melting                                      V -  3
                Magnesium Treatment  for  Producing
                  Ductile Iron                               V -  5
                Molding, Pouring  and  Shakeout                V -  6
                Sand Conditioning                           V -  8
                Cleaning and  Finishing                      V -  9
                Coremaking                                   V -  10
                Pattern Making                               V -  11

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                                                        -  5  -
SECTION                                                   PACE
              Emission Control Capability                  V -  11
                Emissions Controllable with Existing
                  Equipment Design                        V -  12
                Farticulate Emissions  Uneconomical
                  to Control                              V -  12
                    Cupola                                V -  14
                    Electric Arc Furnace                  V -  14
                    Magnesium Treatment for Producing
                      Ductile Iron                        V -  15
                    Mold Pouring                          V -  15
                    Coremaking                            V -  15

   VI       QUANTIFICATION AND EVALUATION OF EMISSIONS
              Description of Sampling and Analytical
                Techniques                                VI - 1
                  General Atmosphere Sampling             VI - 1
                  Stack Sampling                          VI - 5
              Necessity for Stack Sampling Program        VI - 8
                  Test Reports Gathered and Analyzed      VI - 8
                  Need for Additional Data                VI - 9
              Evaluation of Cupola Emissions              VI - 10
                  Nature of Data Gathered                 VI - 10
                  Classification of Melting Processes
                    by Type and Design Parameter          VI - 13
                  Variables Affecting Emissions           VI - 14
                  Analysis of Emissions Data              VI - 19
                  Discussion of Results                   VI - 26
                    Introduction                          VI - 26
                    Variables with  Proven Effect on
                      Emissions                           VI - 27
                                                                                                                                   - 6 -
SECTION                                                   PAGE
                    Cupola Design Variables               VI - 29
                    Variables with Probable Effect
                      on Emissions                        VI - 30
                    Variables with Expected Effect
                      on Emissions                        VI - 32
                    Conclusion                            VI - 33
              Evaluation of Emissions from Other
                Sources                                   VI - 37
                  Electric Arc Melting and Holding        VI - 39
                  Magnesium Treatment for Producing
                    Ductile Iron                          VI - 43
                  Mold Pouring and Cooling                VI - 46
                  Coremaking                              vi - 48

    VII     TECHNICAL ANALYSIS OF EMISSION CONTROL
              TECHNOLOGY
              Analysis of Emission Control Techniques    VII - 1
                Dry Centrifugal Collectors               VII - 1
                  Historical Background                  VII - 1
                  General Characteristics of
                    Equipment                            VII - 2
                  Description of Specific Types          VII - 2
                  Advantages of Dry Centrifugal
                    Collectors                           VII - 7
                  Disadvantages of Dry Centrifugal
                    Collectors                           VII - 7
                  Limitations of Dry Centrifugal
                    Collectors                           VII - 8
              Wet Collectors                             VII - 9
                  Historical Background                  VII - 9
                  General Characteristics of Equipment   VII - 9
                                                                                            A T KEARNEV 6k COMPANY

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                                                      - 7 -
                                                                                                                                        - 8  -
SECTION
                 Description of Specific Types
                 Advantages  of Wet Collectors
                 Disadvantages of Wet Collectors
                 Limitations of Wet  Collectors
              Fabric  Filters
                 Historical  Background
                 General  Characteristics of
                   Equipment
                 Description of Specific Types
                 Advantages  of Fabric Filters
                  Disadvantages of Fabric Filters
                 Limitations of Fabric  Filters
              Electrostatic Frecipitators
                Historical Background
                General Characteristics  of Equipment
                Description of Specific  Types
                Advantages of Electrostatic
                  Precipitators
                Disadvantages of  Electrostatic
                  Precipitators
                Limitations of Electrostatic
                  Precipitators
               Collection  Efficiency  of  Emission
                 Control Equipment Systems
                 Weight
                 Particle  Size Count
                 Opacity
                 Ground Level Concentration
 PACE

VII - 11
VII - 18
VII - 19
VII - 20
VII - 20
VII - 20

VII - 22
VII —24
VII - 27
VII - 28
VII - 28
VII - 30
VII - 30
VII - 30
VII - 32

VII - 34
VII - 35
VII - 36

VII - 36,
VII - 37
VII - 39
VII - 40
VII - 41
SECTION                                                     PAGE
                 Factors Affecting Control Equipment
                   Collection Efficiency                   VII - 41
                 Combustion Devices                        VII - 52
                   Afterburners                            VII - 52
                   Catalytic Afterburners                  VII - 54
              Application of Emission Control Equip-
                ment Systems to Foundry Processes          VII - 55
                  Raw Material Handling, Preparation
                    and Charge Makeup                      VII - 56
                  Cupola Melting                           VII - 57
                    Wet Caps                               VII - 58
                    Dry Centrifugal Collectors             VII - 59
                    Wet Collectors                         VII - 60
                    Fabric Filters                         VII - 60
                    Electrostatic Precipitators            VII - 61
                    Other Techniques                       VII - 61
                  Electric Arc Melting                     VII - 62
                    Emission Collection Equipment          VII - 62
                    Furnace Hoods                          VII - 63
                    Other Methods                          VII - 64
                  Electric Induction Melting               VII - 64
                  Other Types of Melting                   VII - 65
                  Inoculation                              VII - 66
                    Ductile Iron Production                vll - 66
                    Mechanical Property Improvement
                      by Inoculation                       VII - 66
                A.T KEARNEY & COMPANY. l»c

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SECTION
  VIII
      Mold  Pouring,  Cooling and Shakeout
      Sand  Preparation  and Handling
      Cleaning and  Finishing
      Coremaking
      Miscellaneous  Areas
  Case Histories of Attempts  to Control
    Emissions in Iron Foundries
      Melting Processes
      Non-Melting Processes

ECONOMIC ANALYSIS OF EMISSION CONTROL
  TECHNOLOGY
  General
  Capital Costs of Control  Systems
    Cupola Melting
    Electric Arc Melting
  Relation of Capital Costs  of Control
    Systems to Design Variables
      Cupola Melting
      Wet Scrubber Efficiency -
        Pressure Drop Relationship
      Electric Arc Melting
      Other Melting Methods
  Operating Costs of Control Systems
  Relation of Operating Costs of  Control
    Systems to Design Variables
- 9 -

  PAGE
  VII -  66
  VII -  68
  VII -  69
  VII -  70
  VII -  71
  VII -  71
  VII -  72
  VII -  87
                                                       VIII - 1
                                                       VIII - 2
                                                       VIII - 8
                                                       VIII - 9

                                                       VIII - 10
                                                       VIII - 10
                                                       VIII - 14
                                                       VIII - 16
                                                       VIII - 18
                                                       VIII - 18
                                                       VIII - 24
                                                                                   SECTION
                                IX
Effect of Emissions Control on Capital
  and Operating Casts in Model Foundries
   Model Foundry Development
     Melting Systems Studied
     Sizes of Foundries Studied
     Levels of Operation Studied
   Qualifications Regarding Model Foundry
     Design Data
   Equipment and Building Specifi-
     cations
       Melting Equipment
       Emission Control Equipment
       Buildings
   Capital Costs
   Operating Costs
     Direct Material Costs
     Conversion Costs
     Emission Control Costs
   Summary of Capital and Operating
     Costs
Benefits of Emission Control
  Installations
                                         TECHNICAL AND ECONOMIC ANALYSIS OF
                                           POTENTIAL  MODIFICATIONS TO FOUNDRY
                                           PROCESSES  AND EQUIPMENT
                                           Improvement of Emissions Control
                                             Capability
                                           Potential  Modifications to Foundry
                                             Practices and Emissions Producing
                                             Equipment
                                           Potential  Modifications to Cupolas
                                             and Cupola Operations
10 -
PAGE

VIII -  26
VIII -  26
VIII -  26
VIII -  27
VIII -  27

VIII -  28
VIII -  28
VIII -  29
VIII -  29
VIII -  31
VIII -  31
VIII -  32
VIII -  33
VIII -  34
VIII -  35
VIII -  37
VIII -  37
                                                IX - 1

                                                IX - 2
                                                IX - 3

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                                                            -  11 -
SECTION
   XI
   XII
                                              PAGE
      Decrease Stack  Gas  Volume                IX -  3
      Decrease Coke Charge                     IX -  8
      Preparation of  Charge Materials          IX -  11
      Cupola Design Changes                   IX -  14
      Change Melting  Method                   IX -  15
    Potential Modifications to Other
      Melting Furnaces                        IX -  16
    Modifications to  Magnesium Treatment for
      Producing Ductile Iron                  IX  -  17
    Modifications to  Sand Hand]lag Systems     IX  -  18
  Potential Modifications to Emissions
    Control Equipment                         IX -  20
  Impact of Potential Modifications to
    Foundry Equipment and Practices            IX -  22
PROJECTION OF TRENDS
  Growth of the Iron  Foundry Industry            X -  1
  Equipment Trends                              X -  4
  Effects on Emissions                          X -  7
DEFINITION OF THE IRON FOUNDRY AIR
  POLLUTION PROBLEM
  General                                     XI -  1
  Nature of Foundry Emissions                 XI -  1
  Inventory of Foundry Emissions              XI -  4
  Industry Problems                           XI -  8
OPPORTUNITIES FOR RESEARCH AND
  DEVELOPMENT
  Needs  for Research and Development          XII -  1
                                                                                                                                               - 12 -
SECTION                                                    PAGE
                Fundamental Knowledge                     XII -  1
                Economic Factors                          XII -  2
                Materials                                 XII -  3
                Processes                                 XI1 -  3
              Ongoing Research  and Development
                Projects                                  XII -  3
                  Melting  of  Iron                        XII -  4
                  Emissions Collection                   XII -  5
              Proposed  Research and Development
                Projects                                  XII -  6
                  Fundamental Research Projects          XII -  7
                     No.  1.  Stack Sampling Program       XII -  7
                     No.  2.  Iron Oxide Formation
                              Program                    XII -  8
                     No.  3.  Fine Oxide - Opacity
                              Relationship Program       XII -  9
                  Economic Research Projects             XII -  10
                     No.  5.  Waste Heat Utilization       XII -  10
                     No.  7.  Centralized Scrap Pre-
                              paration Development       XII -  11
                     No.  10. Waste Product Utilization    XII -  12
                  Materials Development Projects         XII -  13
                     No.  4.  High Temperature Fabric      XII -  13
                     No.  8.  Low Emission Core Binder
                              Materials                  XII -  14
                  Development of New Equipment           XII -  15
                     No.  6.  Continuous Melting           XII -  15
                              Furnace
                     No.  9.  Agglomeration of Fine        XII -  16
                              Emissions
                                                                                                       A T KEARNEY & COMPANY  INC

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                VOLUME II - LIST OF EXHIBITS
III-l
III-2

III-3
I1I-4
III-5
III-6
III-7

IV-1
IV-2

IV-3
IV-4
IV-5
IV-6
IV-7
IV-8

IV-9
IV-10
         Title
Iron Foundry Production Trends
Population Trends in the Foundry
Industry
Distribution of Iron Foundries,  1969
Geographical Distribution of Iron
Foundries
Iron Foundry Cupola Trends
Iron Foundry Electric Furnace Trends
Characteristics and Sources of Emissions
in Various Foundry Departments
Iron Foundry Process Flow
Process Flow Diagram - Gray, Ductile  and
Malleable Iron
Summary of Gray Iron Specifications
Summary of Ductile Iron Specifications
Summary of Malleable Iron Specifications
Iron Foundry Scrap Specifications
Pig Iron and Ferroalloy Specifications
Process Flow Diagram - Raw Material
Storage and Charge Makeup
Process Flow Diagram - Melting Department
Electric Arc Furnace -  Heat and  Material
Balance
                                                                                                                                             -  2  -
IV-12

IV-13

IV-14
IV-15
IV-16

IV-17
IV-18
IV-19
IV-20

IV-21

IV-22
IV-23
IV-24
IV-25
IV-26
IV-27
         Title
Coreless Induction Furnace - Heat and
Material Balance
Process Flow Diagram - Molding, Pouring
and Shakeout
Process Flow Diagram - Cleaning and
Finishing
Process Flow Diagram - Sand Conditioning
Process Flow Diagram - Coremaking
Illustration of Conventional Lined
Cupola
Illustration of Water-Cooled Cupola
Illustration of Cupola Reaction Area
Illustration of Electric Arc Furnace
Illustration of Channel Induction
Furnace
Illustration of Coreless Induction
Furnace
Illustration of Reverberatory  Furnace
Illustration of Magnesium Treatment
Methods for Producing Ductile  Iron
Illustration of Pouring Station with
Horizontal Draft, Cantilevered Hood
Illustration of Shakeout Station
Illustration of Sand Muller
Illustration of Blast Cleaning Unit

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                                                          - 3  -
Number
VI-1

VI-2

VI-3
VI-4
VI-5

VI-6

Vl-7

VI-8

VI-9

VI-10

VI-11
VI-12

VI-13

VI-14

VI-15

VI-16
          Title
Ringelmann Scale for Grading Density of
Smoke
Pertinent ASME Items Which Must  Be
Conformed to by Parties Conducting a
Stack Sampling Test
Design Features of the Cupola
Design Features of the Electric  Arc
Design Features of the Induction
Furnace
Classification of Lined and Unlined
Cupola Furnaces Found in Practice
Chemical Composition of Cupola
Particulate Emissions
Particle Size Distribution - Cupola
Emissions
Parameters of Cupola Furnaces -
Linear Regression Analyses of Emissions
Affected by Furnace Design Factors
Multiple Linear Regression Correlation
Matrices
Linear Regression Analyses Observations
Particulate Emissions vs Specific  Blast
Rate for Acid Lined Cupolas
Effect of Specific  Blast Rate  and  Coke  Rate on
Particulate Emissions  from Unlined Cupolas
Effect of Type of Scrap on Amount  of
Iron Oxide Present
Results of Size Distribution and
Chemical Analysis for Three Electric
Arc Installations
Emissions Data from Electric Arc
Melting Furnaces
Number
VI-17

VI-18

VI-19

VI-20
VI-21

VI-22

VI-23

VI-24

VII-1
VII-2
VI I-3
VII-A
VII-5
VII-6
VII-7

VII-8
VII-9
VII-10
          Title
Relationship between Rate of Emissions
and Heat Cycle for Electric Arc  Melting
Treatment Agents for Producing Ductile
Iron
Magnesium Treatment Systems Emissions
Report for Ductile Iron Production and
Gray Iron Desulfurization
Molding Sand Gas Analyses
Molding Sand Gas Evolution and Hot
Permeability
Gas Volume Evolved as  a Function of
Volatiles Contained in Molding Sand
Effect of Baking Time  on Gas Generated dur-
ing Pouring for Various Baking Temperatures
Effect of Sand to Oil  Ratio on Amount
of Core Gas Generated  during Pouring
Cyclone  Collector
High Efficiency Centrifugal Collector
Dry Dynamic  Precipitator Collector
Wet Cap  Collector
Wet Dynamic  Precipitator Collector
Vane-Type Centrifugal Wet Collector
Multiple Tube-Type Centrifugal Wet
Collector
Orifice-Type Wet Collector
Centrifugal  Spray Wet Collector
Marble Bed-Type Wet Collector

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                                                                                                                                         - 6 -
VII-12

VII-13


VII-14


VII-15


VII-16

VII-17


VII-18


VII-19


VII-20


VII-21


VII-22

VII-23


VII-24


VII-25



VII-26
          Title

 Impingement Baffle Grid-Type Wet
 Collector

 Venturi Collector

Wet Collector Particle Collection
 Limitations and Design Capacities

 Cutaway View Showing Fabric Filter,
 Flat or Screen-Type Bag

 Cutaway View Showing Fabric Filter
 Tubular-Type Bag

 Intermittent Fabric Filter Collector

 Continuous Automatic Fabric Filter
 Collector

 Reverse Jet Continuous Fabric Filter
 Collector

Wet-Type Electrostatic Precipitator
 Effluent Cleaning System

 Dry-Type Electrostatic Precipitator
 Effluent Cleaning System

 Collection Efficiency of Emission
 Control Equipment Systems

Grading of Test Dust

Overall Collection Efficiency on Test
Dust

Chemical Composition of Cupola Oust
by Weight

Grade Efficiency Curve, Dry Electro-
static Precipitator, High Efficiency
Cyclone

Calculation of Collector Efficiency
VII-28



VII-29



VII-30



VIII-1


VIII-2


VIII-3


VIII-4


VIII-5


VIII-6


VIH-7


VIII-8



VIII-9
          Title

Grade Efficiency Curve for Fabric
Filter, Effect of Particle Size and
Length of Bag in Service on Fabric
Filter Efficiency

Relationship between Collection
Efficiency, Particle Size and  Pres-
sure Drop for Venturi Scrubbers

Cupola Afterburner, Catalytic  After-
burner Applied to Core Bake Oven
Process

Application of Emission Control Equip-
ment Systems to Foundry Processes
Conditions Affecting Installation Cost
of Control Devices

Investment Cost Equations for Equipment
Installed on Cupolas

Total Investment Cost vs Gas Volume
for Wet Scrubber on Cupolas

Total Investment Cost vs Gas Volume  for
Fabric Filters on Cupolas

Total Investment Cost vs Gas Volume
for Mechanical Collectors on Cupolas

Approximate Melting Rates and Gas
Volumes for Lined Cupolas

Approximate Melting Rates and Gas
Volumes for Unlined Cupolas

Comparison of Gas Take-Off above
Charge Door and Below Charge Door.
Lined Cupola, Coke Ratio 8/1

High Energy Wet Scrubber Total Invest-
ment Cost vs Melt Sate for Unlined Cupola
8/1 Coke Ratio

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                                                      -  7  -
                                                                                                            - 8 -
Number

VIII-10



VIII-11



VIII-1Z



VIII-13



VIII.-14



VIII-15

VIII-16


VIII-17


VIII-18


VIH-19


VIII-20


VIII-21


VIII-22


VIII-23
          Title

High Energy Wet Scrubber  Total  Invest-
ment Cost vs Melt Rate for Lined  Cupola,
8/1 Coke Ratio

Low Energy Wet Scrubber Total Investment
Cost vs Melt Rate for Unlined Cupola,
8/1 Coke Ratio

Low Energy Wet Scrubber Total Investment
Cost vs Melt Rate for Lined Cupola,  8/1
Coke Ratio

Fabric Filter Total Investment  Cost  vs
Melt Rate for Unlined Cupola, 8/1 Coke
Ratio

Fabric Filter Total Investment  Cost  vs
Melt Rate for Lined Cupola, 8/1 Coke
Ratio

Total Investment Costs for Wet  Caps

Calculation of Wet Scrubber Efficiency
for Various Pressure Drops

Comparison of Cupola Outlet Dust  Load-
ing and Pressure Drop for Wet Scrubbers

Approximate Exhaust Volumes for Electric
Arc

Installed Cost of Fabric  Filter on
Electric Arc

Total Annual Costs for High Energy Wet
Scrubbers on Cupolas

Total Annual Costs for Low Energy Wet
Scrubbers on Cupolas

Relative Changes in Total Annual  Costs
vs Pressure Drop for Wet  Scrubbers

Total Annual Cost for Fabric Filters on
Cupolas
VIII-25
VIII-26
VIII-27
VIII-28
VIII-29
VIII-30
VIII-31
VIII-32
VIII-33
          Title

Total Annual Cost  for Fabric  Filters  on
Electric Arc

Comparison of Cost  per Ton  of Melt  for
High Energy Wet Scrubber  on Unlined
Cupola at Different Levels  of Operation,
5/1 Coke Ratio

Comparison of Cost  per Ton  of Melt  for
High Energy Wet Scrubber  on Lined Cupola
at Different Levels of Operation, 8/1
Coke Ratio

Comparison of Cost  per Ton  of Melt  for
Low Energy Wet Scrubber on  Unlined
Cupola at Different Levels  of Operation,
5/1 Coke Ratio

Comparison of Cost  per Ton  of Melt  for
Low Energy Wet Scrubber on  Lined Cupola
at Different Levels of Operation, 8/1
Coke Ratio

Comparison of Cost  per Ton  of Melt  for
Fabric Filter on Unlined  Cupola at  Dif-
ferent Levels of Operation, 5/1 Coke
Ratio

Comparison of Cost  per Ton of Melt  for
Fabric Filter on Lined Cupola at Different
Levels of Operation, 8/1  Coke Ratio

Summary of Capital Costs  to Produce
Iron under Various Production and
Operating Conditions

Summary of Operating Costs  for Produc-
ing Iron under Various Production and
Operating Conditions

Capital and Operating Costs per Ton
versus Operating Hours per Year for
Cold Blast Cupola with Fabric  Filter
(Alternate No.l)

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                                                         - 9 -
Number

VIII-34




VI1I-35




VIII-36
          Title

Capital and Operating Costs per Ton vs
Operating Hours per Year for Hot Blast
Cupola with Wet Scrubber (Alternate
No. 2)

Capital and Operating Costs per Ton vs
Operating Hours per Year for Electric
Arc Furnace with Fabric Filter (Alternate
No. 3)

Capital and Operating Costs per Ton vs
Operating Hours per Year for Cureless
Induction Furnace with Afterburner on
Preheater (Alternate No. 4)
                VOLUME  III -  LIST OF APPENDICES


APPENDIX                      TITLE

    A            Bibliography

    B            Data Bank

    C            Material  and Heat Balance

    D            Detail Economic Cost Curves

    E            Emission  Test Procedures

    F            Glossary  of  Terms
IX-1
Modifications to Cupola Melting Prac-
tices to Reduce Emissions
XI-1


XI-2


XI-3

XII-1
Inventory of Iron  Foundry Emissions from
Melting Operations,  1969

Inventory of Iron  Foundry Emissions from
Non-Melting Operations, 1969

Priority Rating Chart

Proposed Research  and  Development  Projects

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           NATIONAL AIR POLLUTION  CONTROL OFFICE
                 CONTRACT HO.  CPA  22-69-106
          SYSTEMS ANALYSIS OF  EMISSIONS AND EMISSIONS
             CONTROL IN THE  IRON FOUNDRY INDUSTRY
                        VOLUME I TEXT
          	FEBRUARY.  1971	
                      I - INTRODUCTION

ACKNOWLEDGEMENTS
     A. T. Kearney & Company,  Inc. gracefully acknowledges Che
many people and organizations  who  cooperated and assisted in this
study.
     We acknowledge the cooperation  and assistance provided by
the'American Foundrytnen's Society  and the Gray and Ductile Iron
Founders' Society in furnishing information and in obtaining the
cooperation of their member  foundries.  In addition, A.F.S. pro-
vided the use of its headquarters  for review meetings with the
Industry Liaison Committee.
     We acknowledge the assistance provided by the members of
the Industry Liaison Committee who were helpful in reviewing the
progress of the study and providing  a critique of the report.
     We acknowledge the assistance and cooperation of the many
iron foundries who provided  A. T.  Kearney & Company the courtesy
of plant visits and furnished  data for this study and for the
data bank.
     We acknowledge the assistance and cooperation of the various
manufacturers of foundry equipment and the manufacturers of
                                                                                                                                        1-2
emission control equipment  for providing  valuable  technical
and economic data.
     Finally, we thank the  staff of APCO  for  their assistance and
guidance.

     This report was prepared by a project  team of A.  T.  Kearney
staff and associated consultants.  The  overall  direction  was un-
der Mr. E. Stuart Files, Vice President of  A. T. Kearney  &
Company, Inc.  The Project  Director was Mr. Joseph H.  Greenberg,
Principal, and the other members of the team  were  Mr.  Robert E.
Conover, Senior Associate;  Mr. Bernard  Gutow, Associate;  and
other members of the Kearney Organization.  The associated con-
sultants who provided valuable assistance in  carrying  out of the
work were Mr. John Kane, Mr. George Tubich, and Mr.  James Ewens,
all independent consultants in air pollution  control and  foundry
operations.
PURPOSE OF
  THE STUDY
     The Air Pollution Control Office has the task of  developing
technology for a national program for control of air pollution
and, as a part of this program, is conducting a series of systems
analysis studies of various industries.   These  studies are being
conducted by the Division of Process Control  Engineering.   This
study is directed at the iron foundry industry,  with particular
emphasis on the melting area.  The primary  goal of the study is
to define the air pollution problems of the iron foundry  indus-
try, and to set priorities  for research and development work that

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                                                       1-3
will lead Co improved emission control capabilities  at reduced
cost.
SCOPE OF THE
  STUDY	
     For the purposes of chis study, the iron foundry industry
was defined as those shops that melt iron (including iron and
steel scrap) in furnaces, pour the molten iron into  molds,  and
alloy and/or treat the iron in either the molten or  cast state,
with processes limited to making gray, malleable, and ductile
cast iron.  This definition excludes blast furnace processes,
including direct casting of blast furnace metal into molds, and
processes for converting iron to steel.
     The following iron foundry facility and operations areas
were included in the study:
          1.  Raw materials receiving, storage, handling, prepara-
tion, and charging.
          2.  Iron melting, duplexing, holding, desulphurization,
inoculation, and magnesium treatment for producing ductile iron.
Equipment includes cupolas, direct and indirect electric arc  fur-
naces, coreless and channel induction furnaces, stationary and
rotary fuel fired furnaces, inoculation and magnesium treatment
units.
          3.  Sand molding, pouring, cooling, shakeout, sand
handling, storage, preparation, and distribution.
          4.  Casting cooling, cleaning, grinding, heat treat-
ing, and painting.
                                                                                                                                  1-4
          5.   Coremaking of oil-bonded, chemically bonded, and
other types of cores.
          6.   Other auxiliary areas in the iron foundry Chat
produce emissions.
LITERATURE SEARCH
  AND BIBLIOGRAPHY
     An extensive search of the literature was conducted to Identi-
fy and list in a single bibliography published material'pertinent
to the subject of this study.  During the course of this litera-
ture search, approximately 191 information sources, including
serial publications, have been identified.
     A total of 735 references of related material were cataloged,
including 511 articles in technical journals, 213 books, and
miscellaneous publications by industry, technical societies,  and
governmental bodies, plus 11 patents.
     Appendix A is a copy of the bibliography which is  arranged
by calendar year and subdivided into categories of books,  reports,
and articles.
GLOSSARY OF
  TERMS
     Standard iron foundry industry and air  pollution terminology
are used throughout  this report.  Definitions of these  terms  are
provided in Appendix F, Glossary of Terms, found in Volume III
of this report.

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              II  - SUMMARY AMD RECOMMENDATIONS

SCOPE AND
  OBJECTIVES
     the Air Pollution Control Office has Che cask of developing
technology for a  national program foe control of air pollution
and, as a part of this program, sponsored a series of systems
analysis studies  of  various  industries which are primary sources
of air pollution.  This study was directed at the iron foundry
industry, with particular emphasis on the melting area, and was
conducted by A. T. Kearney & Company, Inc.

     The primary  goal of the study was to define the air pollu-
tion problems of  the iron foundry industry, and to set priorities
for research and  development work that will lead to improved
emission control  capabilities at reduced cost.

DESCRIPTION OF
  THE IRON FOUNDRY
  INDUSTRY	
     The number of gray, malleable and ductile iron foundries
in the United States hos decreased from about 3,200 in 1947 to
1,670 in 1969, with  a trend  of reducing by about 70 installations
per year.  These  foundries are located in 48 states, although
80% are located in only 13 states.  Of all iron foundries,  only
about 525, or 297., can be classified as medium and large
foundries, employing more than 100 people, and only 91 can  be
called very large.
                                                                                                                                           II  -  2
     The cupola is still by far the moat common method of melt-
 ing  iron,  with  about  1,970 cupolas in service In 1970.  This Is
 a  decline of 2,500 in the past 25 years.  This decline can be
 expected to  continue, as more foundries arc closed, and others
 convert  from cupola to electric melting.  Electric arc installa-
 tions  are  increasing  rapidly as are electric induction
 installations.

     The information  available regarding the other productive
 operations in iron foundries which are sources of emissions is
 not nearly as well documented as the melting area.   However,  we
 know that all foundries  employ some kind of molding practice,
 with most iron  foundries  using sand molding.   The modern trend
 is toward automated or semiautomated molding,  employing con-
 veyors of some  type for moving molds past each of the stations.
 This can be expected  to  increase as more foundries  automate
 or mechanize  their operations.

     Coremaking is  another  area that is  undergoing  rapid
 changes, with the  trend  being away  from  oil-bonded,  baked sand
 cores, toward chemically  bonded,  thermally  cured  cores.

     The widespread distribution of iron foundries,  and the
 prominence of the  cupola  stack in nost communities  in which an
 iron foundry  is located,  have combined to label the  iron foundry
 as a major source of  air  pollution.   It  has  been  estimated  that
 iron foundries produce 243,000 tons  of particulates  in the
United States each  year.  Although  some  of  these  are  now captured

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                                                      II - 3
by che presently used emission  control  equipment, a large per-
centage is being discharged  Co  che  atmosphere, equal Co abouC
0.9% of all participate  matter  emitted  by all sources.
     The pollutants discharged  by Che iron  foundry indusCry can
be classified as:
          1.  Emissions  from melting furnace operations.
          2.  Emissions  from other  dust-producing operations
within the plant.
          3.  Odors and  gaseous compounds from both sources.

EMISSIONS PRODUCED
  AND CONTROL CAPABILITY
     Processes in the iron foundry  can  be divided into six
production areas:
          1.  Raw material storage, preparation  and charging.
          2.  Metal melting.
          3.  Molding, pouring  and  shakeout.
          A.  Sand conditioning and reclamation.
          5.  Cleaning,  heat treating and finishing.
          6.  Coremaking.
     Each operation contains equipment  and  processes capable
of producing air pollutants  in  Che  form of  noxious fume,  and/or
particulate matter.  The latter ranges  from metal dust from
grinding operations, that is relatively easy and inexpensive
to control, to extremely fine  ferrous and nonferrous oxides and
smoke from melting furnaces that are very expensive and diffi-
cult to control.
                                                                                                                                           II -
     Over the years, increasing attention to foundry and other
industry sources of pollution has prompted development of
numerous methods and techniques for control of emissions from
these sources.
     Of all techniques available to control foundry pollutants,
emission collection equipment systems are the most significant.
These systems, which include dry centrifugals, wet collectors,
fabric filters and electrostatic precipitatora, vary widely
in design, capabilities, cose and application.
QUANTIFICATION AND
  EVALUATION OF
  EMISSIONS	
     Although the majority of gray iron  foundries currently
do not have collection equipment systems  for  control  of  emissions
from melting operations, the number of installations  of  these
systems has increased rapidly the last few years.
     By far the majority of the foundries use cupolas, with
only about 15% of production made using  other forms  of melting.
The major components of particulate emissions from  Iron  melting
cupolas can be grouped into three major  categories:   (1) metallic
oxides  (2) silicon and calcium oxides, and  (3) combustible
materials.
     The amounts of metallic oxides occurring in cupola  emissions
are related to the presence of Che respeccive metals  in  Che
scrap charge and their partial vapor  pressures at the temperature
of Che  cupola melting zone.

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                                                      II - 5
                                                                                                                                  II - 6
      The oxides  of silicon and calcium, representing the second
 category, result from  lining erosion, embedded molding or core
 sand on foundry  returns, dirt from the scrapyard adhering to
 scrap, or from the limestone flux.
      The third category of emissions, combustible material,
 includes coke particles, vaporized or partially burned oil and
 grease and other contaminants swept up Che stack by the top
 gases.
      The effects of  15 variables on the type and quantity of
 cupola emissions have  been evaluated by the use of a variety
-of analytical techniques.  The analyses demonstrate that some
 of the variables have  strong and quantifiable effects and
 others have insignificant effects on emission levels.
      Although the cupola has been considered to be the principal
 source of iron foundry emissions which are difficult or costly to
 control, there are other areas in the foundry which also produce
 these types of emissions.  Some of these have been adequately
 and economically controlled with existing designs of equipment,
 while others have proven to present problems which have not
 yet been completely  solved.
      The ease and cost of controllability can generally be re-
 lated to two broad  aspects:   the problems which relate to cap-
 turing the emissions with a minimum of infiltrated air and the
 problems of adequately removing the offending fine particles
 and gases from the captured effluents before releasing them to
 the  atmosphere.   In general,  those operations which in many
 foundries  take  place in open,  nonconcentrated, nonstationary
 locations  are difficult to control although in many cases,
 the  actual costs  of control may not be high once the effluents
 are  captured.   Such operations occur in the scrapyard, mold
 pouring  area, and the shakeout area.

     The other  areas which involve difficulty of capture and
 high cost  of control equipment include melting,  inoculation and
 coremaking.

 TECHNICAL  ANALYSIS
  OF CONTROL TECHNOLOGY
     A detailed analysis was presented of each of the types of
 emission control  equipment  in  use  in each of the areas of the
 iron foundry.  This  included a description of the equipment,
 its  application,  historical background,  and its  relative posi-
 tion as  compared with other equipment.   Case histories of past
 attempts to abate emissions were cited.   In general,  it  was
 demonstrated that equipment and methods  exist  for control of
 almost all foundry emissions,  although in many cases  the
 economics  are unfavorable, particularly  for small foundries.

 ECONOMIC ANALYSIS
  OF CONTROL TECHNOLOGY
     Estimates have  been made  of the capital costs  and annual
 costs of operation of control  systems  based upon  analysis of
 existing and proposed installations.  The cost data obtained
were all basically for  foundries with  cupolas  controlled with

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                                                     II - 7
wet caps, mechanical collectors,  fabric  filters, and high and
low energy wet scrubbers,  and for electric  arc  furnaces con-
trolled with fabric filters.
     The major factor that influences  capital cost is the type
of melting equipment.   The complexity  of control systems is
greatest for the cupola, moderate for  the electric arc, and
least for induction melting.
     A number of design and operating  variables are related
to the total cost of emission control  systems.  These include
melt rate of the furnace,  pressure drop  of  the  system, blast
volume in standard CFM and gas volume  throughput in actual
CFM.  A computerized multiple regression analysis of the
collected data has confirmed that total  costs varied most
directly with actual gas volume throughput.
     A comparison of the impact of annual costs was made for
wet scrubbers and fabric filters.  These were the more popular
and commonly used types of control systems  observed on foundry
melting equipment.  These  operating costs were  given in terms of
cost per ton of metal melted for wet and dry collectors on
cupolas and arc furnaces.
     A series of model foundries developed  as a means of relating
the economics of emission  control installation  and operation to
the total costs of installing and operating iron melting depart-
ments.  These models covered the complete melting department
of foundries with melting  capacities of  5,  IS,  30 and 50 cons
                                                        II  -  8

per hour, and operating at varying  levels, including  500,  1,000,
2,000 and 4,000 hours per year.  Melting methods  included
cupola, arc furnace and induction furnace.  Costs  of  emission
control installation and operation  were identified as a  percentage
of total costs for each of these conditions.
POTENTIAL MODIFICATIONS
  TO FOUNDRY PRACTICES
  AND EMISSIONS PRODUCING
  AND CONTROL EQUIPMENT
     Of all foundry operations causing emissions  to be  released
to the atmosphere in some degree, the melting operation  has  re-
ceived the greatest attention.  The effort to improve collection
capability of a lower cost has been concentrated  on the  problem
of the cupola as the source of the  greatest amount of particulate
matter.  The results of these investigations in recent years
have been a number of modifications offering at least a  partial
solution to the problem.

     Other work has been done in the areas of preheating,
magnesium treatment for producing ductile iron, pouring  and
cooling, sand handling and coremaking.

     Cupolas and cupola operations can be modified in an attempt
to achieve two goals:  to decrease the cost of emissions collec-
tion and to decrease the quantity of emissions requiring
collection.   One method of decreasing the volume of cupola
stack gas is to limit air infiltration by reduction of the
charging door area.   Locating the gas take-off below the top  of
the charge burden is a second method of reducing air infiltration

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                                                       II - 9

 and  thereby decreasing the volume of gas to be cleaned.

     Reduction of coke in cupola charges offers some beneficial
 results.  The evaluation of cupola emissions indicates that
 particulate emissions tend to decrease as the amount of coke in
 the  cupola charge decreases.  Heating of the cupola blast air
 has  been recognized for many /ears as one method of increasing
 the  melting rate with the same coke charge or of maintaining
 the  melting rate with a smaller coke charge.   Oxygen enrichment
 of the blast air also results in a decrease in coke requirements
 by reducing the 60% nitrogen in air which would otherwise
 require heating to the iron meltiitg temperature in the cupola.
 Natural gas injection, like oxygen enrichment,  provides  a means
 by vhich cupola coke requirements can be reduced,  melting rate
 increased, melting costs lowered, and a modest  decrease  in par-
 ticulate emissions can be realized.

     Screening of limestone and coke before loading into the
 charging bucket is an elementary and inexpensive step  to pre-
 vent breeze and dust from being charged into  the cupola.   Scrap
 preparation is more often performed by scrap  dealers than
 foundry personnel due to the equipment cost and labor  require-
ments.   An increasing amount of today's scrap is  automotive,
 consisting of whole or broken engines or fragmented bodies.

     The increase in the number of electric and reverberatory
melting furnaces in recent years,  at a time when  the number of
 iron foundries have decreased dramatically, is  evidence  that
                A T KEARVEY 61 COM PAN Y. Inc.
                                                         II - 10

 one acceptable solution to  the  problem  of the high cost of
 emissions control is to replace  the cupola by a furnace that
 produces less emissions.  Installation  and melting costs of al-
 ternative furnaces are not  always  lower,  but  the total of the ad-
 vantages sometimes tips the scale  in  favor of cupola replacement.
      Improvements in emissions control  equipment  rn  the fore-
 seeable future,  with few exceptions, promise  to  be minor  in
 nature.  These will be results of efforts  by  the manufacturers
 of this equipment to improve quality of manufacturing,  use of
 better materials  and redesign to raise efficiencies and lower
 costs  of their products.
 PROJECTION
   OF TRENDS
     Total iron castings production,  excluding ingot molds made
 from direct blast  furnace  iron,  has been projected to be approxi-
 mately  17 million  tons per year  by  1980, or an average 2%
 increase per year.

     The number of foundries which  will  be in  operation by 1980
 has been projected to be approximately 1,100.   Since the number
 of medium- and large-sized foundries has been  projected to in-
 crease slightly,  the entire  drop  from  the  1969 total  of 1,630
 foundries to 1,100 foundries is expected to take  place among
 the small-sized companies.   The combination of increasing  output
and reduced number of producers is expected to continue to
increase the average output per foundry  to  an  estimated 16,500
tons per year by  1980.
                                                                                                A T KEARS'EY fl. COMPANY. INC

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                                                      II - 11

     The most significant  changes  in the  types and uses of
equipment which are expected to  take place  in Che iron foundry
are in the melting department.   The  cupola, which once was
almost the only source of  molten iron,  has  been rapidly declining
in number of installations,  with the number in 1969 being only
about 45% of tKose In existence  immediately after the war.  This
decline has been projected to continue  at an undiminished rate,
with the number of cupolas in 1980 estimated to be about 1,300.

     In 1969, an estimated 85% of all iron  melted in iron
foundries uas performed in cupolas.   As the replacement of
cupolas by other forms of  melting continues to accelerate, the
amount of iron melted in cupolas will decrease, with the amount
by 1980 projected to be as low as  50£ of  the total.  The electric
methods of melting, both direct  arc  and induction, will account
for almost 50%, with the small remainder  being melted in fuel
fired, reverberatory furnaces.
     The tonnage of malleable iron which  is produced is expected
to remain relatively constant.   On the  other hand, the tonnage
of ductile iron has been increasing  every year and is expected
to be about double the 1969 tonnage  by  1960.  This will result
in a corresponding increase in the amount of magnesium treatment
of iron which will be performed.
     The trend toward mechanization  of  molding, pouring and
shakeout lines has been continuing at an  increasing rate.
There is every reason to believe that within the next 10 years,
                A T KEARNEY 8>  COMPANY [NC
                                                       II - 12

 the majority of iron foundries  will  use some form of mechanized
 molding,  pouring,  shakeout  and  sand  preparation.

      Coremaking has  also  been undergoing a technological change,
 with the  trend being away from  oil-bonded, baked  sand cores,
 toward chemically  bonded, thermally  cured and air cured cores.

      The  entire area of handling and preparation  of materials
 used in the  foundry  is continually being reviewed with respect
 to  the effect  on emissions  production and economy of collection.
 Iron foundries are being  more selective ir purchasing of scrap,
 with more attention  being given to elimination of combustible
 materials from the scrap  before purchase.   Larger foundries
 are installing scrap preparation facilities involving pre-
 burning or cleaning  to remove materials  which will produce
 emissions during melting.

      Many of the trends toward  electric  or fuel fired melting
 furnaces,  mechanized molding, and continuous  sand preparation
 systems will have  important effects  in reducing the quantity
 of  emissions produced, or in making  the  emissions easier or
 less  costly  to collect.   The decisions made in selecting new
 equipment are,  therefore, being made  to  an increasing degree
with  reference to  the effect on reduction  of  emissions,  or on
economy of emissions collection.

     The  use of a  greater amount of pre-cleaned or  burned scrap
will  reduce  the  quantity  of emissions  from combustibles  now
charged into furnaces along with the scrap.  The  trend away
                                                                                                 A T KEARNEY & COMPANY, rue

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                                                     II - 13

from cupola melting and  toward electric or fuel fired melting
furnaces will have a significant effect in reducing emissions.
     The mechanization of molding, pouring, shakeout and sand
preparation facilities has  not reduced the quantities of
emissions which are produced, but has resulted in confining
their production to fixed  locations.  Thus, it is relatively
simple In many cases to  construct enclosures which can be used
as a means of collection of emissions with a minimum of in-
filtrated air.
DEFINITION OF
  IRON FOUNDRY
  AIR POLLUTION
  PROBLEMS
     The principal areas in which  emissions which are difficult
or uneconomical to collect in the  iron  foundry have been
identified as iron melting, particularly in the cupola, and
in coremaking.  Particulate emissions from all iron melting
operations have been estimated to  total 243,000 tons per year,
of which approximately 182,000 have  been estimated to be dis-
charged to the atmosphere.  Emissions from each foundry source
were evaluated with regard to variables of quantity, particle
size, difficulty of collection, availability and cost of
equipment, economics, and reliability of equipment.  A rating
system was developed to identify the areas of highest priority
with regard to additional development work required.
                A.T KEARNEY ft COMPANY. INC
                                                       II - 14

RECOMMENDED RESEARCH
  AND DEVELOPMENT
     The gaps between existing knowledge, equipment  and
techniques and the necessary levels  required  to efficiently and
economically control emissions in the  iron  foundry were
identified in the areas of fundamental knowledge, economics,
materials, and processes.  Ongoing research and development
in these areas was identified, as far  as  information was avail-
able.  A group of 10 research and development projects was
recommended to bridge the gap between  existing  and required
technology.  For each of these projects the goals, procedure,
estimated time and costs, and priorities were developed.  The
recommended projects are summarized  as follows:
          No. 1.  Controlled stack sampling program  of emissions
from cupolas to determine effects of design and operating
variables on the quantity and type of  emissions.
          No. 2.  An extension of Project No. 1 to provide
quantitative data on effect of variables on iron oxide formation
in the cupola.
          No. 3.  An extension of Project No. 1 to provide data
on relationship between quantity of  fine metallic oxides in
cupola gases and opacity of stack plume.
          No. 4.  Development of fabric materials for fabric
filters, which will be resistant to  high temperatures and
corrosive gases.
          No. 5.  Development of Improved means for  efficient
utilization of sensible heat and heat  of combustion  of cupola
                                                                                                       A T KEARNEY & COMPANY INC

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                                                      II - 15

stack gases.
          Ho.  6.   Development of continuous Iron melting fur-
nace as a replacement for the cupola, using fuel firing or
electric power for economical, low emission melting.
          Ho.  7.   Development of economical, centralized scrap
preparation facilities to serve iron foundries.
          Ho.  8.   Development of core binder materials with low
level of acrid or noxious gas evolution during  curing.
          Ho.  9.   Development of sonic  or other method of
agglomeration of fine particles to make them easier  to collect.
          No.  10. Development of uses  for waste products from
iron foundry melting operations.
                 A T KEARNEY & COMPANY. INC
              III - AIR POLLUTION AND THE IRON
              	FOUNDRY INDUSTRY	
DESCRIPTION OF THE
  IRON FOUNDRY INDUSTRY
Iron Castings
  Production
      Annual castings production in Che United States has varied
widely, depending on the economy, with the ranges during the
postwar period as follows:
                                         1  2
                 Iron Foundry Production  '
Production Tons per Year
Type of Metal
All Metals
All Reported Cast
Iron
Cast Iron from
Iron Foundries
Gray Iron
Malleable Iron
Nodular Iron
Minimum
13,200,000
11,032,000
10,000,000
9,340,000
661,000
-
Maximum
20,800,000
17,084,000
14,486,000
11,936,000
1,227,000
1,570,000
Last 5-Year
Average
20,000,000
16,329,000
13,817,000
11,650,000
1,075,000
1,092,000
                                                                                    The  complete  castings  production picture has been shown
                                                                               graphically  in  Exhibit III-l.  The  data,  as reported by the
                                                                               Department of Commerce,  included the production of ingot molds.
                                                                               However,  only about  30%  of  ingot molds are produced from gray
                                                                               iron melted  in  cupolas,  with the rest being produced from
                                                                               direct  blast furnace metal.   Since  castings production from
                                                                               direct  metal was excluded from this study by definition, and
                                                                               additionally has already been covered by  the iron and steel
                                                                               industry  study, the  estimated portion of  ingot mold production
                                                                                                A.T.KEARNEY a> COMPANY. INC

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                                                     Ill - 2

produced from this source was  deducted  from total iron castings
production.
     Iron castings produced in foundries have accounted for
approximately 691 of total weight  of castings production from
all metals.  Nonferrous metals have  accounted for approximately
8%, steel castings were approximately 10%, and ingot molds
from blast furnace iron accounted  for the remaining 13%.  From
these figures, it is evident that  iron  castings  are by  far the
most important classification  of metal  cast on a tonnage basis.
The rate of increase of iron castings production has been
found to be closely related to three industries—steel, con-
struction and automotive.  Ingot mold castings production
amounts to approximately 8% of iron  foundry production and
varies with steel industry production rates.  Pressure pipe,
soil pipe and fittings production  amount to approximately 201
of total iron foundry production and varies with domestic,
industrial and public construction levels.  Miscellaneous
castings production covers the balance  of 72% of iron foundry
output and varies most closely with  automotive,  truck, bus,
and agricultural vehicle production. This  last  item includes
gray iron, ductile iron and malleable iron castings.

Iron Foundry
  Population
     The population trends in the  foundry industry have been
developed  in Exhibit III-2.  The total  number of foundries of
all types  has remained relatively  constant during the postwar
                                                                                                                                           III -  3
period, ranging from  5,000  to  5,800  and averaging approximately
5,400.  However,  the  iron foundry  population has shown a steady
decline, from 3,200 in  1947, to  1,670  in 1969.   If this decline
continues,  the number of iron  foundries is projected to be approxi-
mately 1,100 by 1980.   However,  the  average size of iron foundries
has been increasing steadily,  with average annual production per
foundry going from 3,800 tons  in 1947,  to 5,300 tons in 1959, and
to 8,700 tons in  1969.  By  1980, the average production per iron
foundry is  projected  to be  approximately 16,500 tons per year.

     An analysis of the population of iron foundries with
respect to size of foundry  has shown that  almost the entire
decline in  foundry population  has  been  among the small foundries,
with employment of under 100 per foundry.   The  number of medium-
sized foundries has remained almost  constant, while the number
of large foundries has  increased slightly.   The number of
small foundries had declined by  one-third  from  1959 to 1969,
and is expected to further  decline to only about half of the
1969 population by 1980.

Geographical Location
  of Iron Foundries
     The distribution of iron  foundries  by states and by major
metropolitan areas is shown in Exhibit  III-3.   The highest
concentration is in the states which border on  the Great Lakes,
namely, Pennsylvania, Ohio, Michigan, Illinois,  Wisconsin,
New York and Indiana.  This group  of seven states contains

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                                                     Ill  - 4

almost half of all of the iron foundries  in the United States
and more than half of the iron castings capacity.  The State
of California contains the greatest concentration of  iron
foundries in the western half of the country, with one-third
of the iron foundries in that 17-state area being in  California.
Other areas of high iron foundry concentration are in the
southeastern states and in the northern states bordering on
the west bank of the Mississippi River.
     The location of the principal concentrations of  iron
foundries has been pinpointed into major  metropolitan areas.
A total of 50 such areas accounts for more  than two-thirds of
the iron foundries.  Here again, the principal concentration
is in the industrial cities in the seven  Great Lakes  states,
with two-thirds of these centers being in,  or bordering on,
those states.  It is of further interest  to note that the
decline in number of iron foundries in these areas was a con-
siderably lower rate than for the balance of the country,
emphasizing the fact that the greatest mortality in iron
foundries has been among the smaller companies located in  the
smaller metropolitan areas.
     The variations which have occurred in  the distribution
of iron foundries by states during the period of 1963-1969 are
given in Exhibit III -It.
Iron Foundry
  Melting Equipment
     Trends in use of iron foundry melting  equipment  are given
for the postwar period on Exhibit III-5.   The cupola has shown
                                                       III - 5

 the most dramatic  change, with  the  number  of cupolas  installed
 in the United States  declining  steadily  from 4,470 in 1947,
 to 1,930 in  1969.3  This decline  can  be  attributed to a com-
 bination of  several factors:
           1.  The decline in the  number  of iron  foundries,
 particularly the small foundries.   For the most  part  the
 foundries which ceased to exist were  operators of  cupolas.
          2.  The replacement of  cupolas by electric  melting
 furnaces.
          3.  The replacement,  in many foundries,  of  two or
more small cupolas by one 'larger  unit.

     The trend toward decline in  the  number of cupolas  is
expected to  continue  for the foreseeable future, with the pro-
jected number being reduced to  approximately  1,000 by 1980.
Although the reasons given above  are  expected to continue to
be the principal factors in this decline,  other  major factors
are most certainly the relatively high cost of installing
effective emission control equipment on cupolas  and the  20-year
history of rapidly increasing cost of coke which is the  source
of fuel as well as carbon in the cupola.

     There have also been changes in the types of  cupolas in
operation with an increasing percentage of  the new installations
being hot blast units, many of them of the unllned, water-cooled
type.   The percentage  of new installations which are  of  the hot
blast type has increased from 24% during Che period of 1947-1956,
to 26% from 1957 to 1962, and to 47% from  1963 to  1968.  At the
same time the number of unlined, water-cooled, hot blast cupolas

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                                                      Ill - 6
has been increasing from its beginnings in the mid-1950's
Co approximately 15% of all cupolas in service in  1969.

     Trends in cupola installations have varied with the sizes
of the foundries.  The small foundries have  invariably installed
hot or cold blase, lined cupolas,  but few water-cooled, unlined
cupolas.  Medium-sized foundries have installed both lined and
unlined cupolas.  The very large foundries have not installed
cold blast cupolas in recent years,  although some  lined, hot
blast cupolas have been erected.  For the most part, the in-
stallations in the large foundries have been water-cooled, un-
lined, hot blast cupolas.   These trends also have been greatly
influenced by the method of operation of the foundry.  Contin-
uous tap melting for one or two shifts per day is well adapted
to hot blast cupola operation,  either lined  or unlined.  On
the other hand,  intermittent, batch melting  is more suitably
served by a cold blast cupola.

     The trend toward electric  melting in iron foundries has
been accelerating rapidly, as shown on Exhibit 1II-6.  Although
some scattered electric melting installations  existed in iron
foundries prior to the mid-1950's,  the great majority of the
installations were made during  the period of 1960-1970.  The
most recent census of foundries, taken in 1969, has revealed
that there were some 374 electric  arc furnaces installed in
176 iron foundries in the United States.   However, an analysis
of these installations has shown that more than half of these
foundries also produce steel castings, utilizing many arc
furnaces for this purpose.  Since  many foundries which produce
                                                        III  - 7

 both iron and steel castings use the same melting  furnace  for
 both purposes, the actual number of arc furnaces used  for  iron
 melting has been estimated to be approximately 200,  located in
 some 100 foundries.  Most of these are used for melting, but
 there are about 35 installations in which the arc  furnaces  are
 used for holding,  duplexing and superheating of iron.

      The number of arc furnace installations for iron melting
 has  been increasing at a rate of about 15 furnaces per year.
 If this  rate  were  to continue,  the number of such  furnaces
 could be expected  to reach approximately 350 by 1980.  However,
 as previously noted,  the combined effects  of high costs of
 installing  emission controls  on existing cupolas,  and the
 rapidly  rising costs  of coke, will in  all  probability accelerate
 the  rate of replacement of cupolas  by  electric  melting furnaces.
The  number  of arc  furnaces melting  iron will, therefore,  be
 higher than the straight  line projection,  possibly in the range
 of 400 to 450 furnaces  by  1980.   For the most part, the electric
 arc  furnace installations  have  been replacing cupolas in
existing  foundries, although there have been several new -
 foundries built in  recent  years  in which arc furnaces were
installed.

     In  1969, there also were 495 coreless Induction furnaces
installed in  191 Iron foundries.   Approximately half of  these
furnaces were in foundries which also produced steel castings.
Since many of these Iron and steel foundries use the same
furnaces for melting both metals, the actual number of  these

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                                                      Ill  -  8
coreless induction furnaces which are used for melting  iron  is
estimated to be approximately 300, located in some  125  foundries.
Most of the coreless induction furnaces are used for melting,
but about 50 of them have been used for holding,  superheating
and pouring of iron.  The number of coreless induction  furnace
installations has been increasing at a rate of approximately
50 per year.  As was the case for the arc furnaces, this  trend
will probably accelerate, resulting in an estimated 700-800
furnaces in iron foundries by 1980.

     In 1969, there were reported to be 489 channel induction
furnaces installed in 134 iron foundries.  Although a few of
these are used as melters, most of them are used for holding,
duplexing, superheating and pouring of iron.   These have  been
increasing at a rate of about 25 installations per year.   If
this rate continues, there will be an estimated 600 units in
service by 1980.

     Fuel fired melting and duplexing furnaces which are  used
in iron foundries generally fall into two classifications:
the reverberatory-type, tilting furnaces used for melting and
the stationary, reverberatory, air furnace used for duplexing
of malleable iron.  There has been an increase in the number
of reverberatory melters in recent years, with the  number in
service now estimated to be approximately 100, in about 80
foundries.  These are increasing at a rate of about SO  per year
and may be expected to reach a total of about 250 installations  by
1980, if this rate were to continue.
                                                                                                                                           Ill - 9
     The reverberatory air furnace was once  found  in  every
malleable iron foundry.  However, no new furnaces  of  this type
are now being built, and the existing installations have de-
clined to about 75, located in about 55 foundries.  These can
be expected to continue to decline as they are  replaced by
electric furnaces.  By I960, the number in service is estimated
to have declined to about 40 units.

     Preheaters, a type of fuel fired equipment associated with
electric arc and electric induction melting  furnaces,  have
found increasing application in the iron foundry.  These units
are used to both preheat scrap and to burn off  combustible
materials that nay be embedded in or coated  on  the scrap,
before charging into the melting furnace.  The  number of such
units Is still relatively few--no more than  50—but their use
is increasing rapidly, and many of the induction melters will
be equipped with preheaters in the future.
Other Equipment
  in Iron Foundries
     Most of the iron foundries employ a form of sand or
ceramic molding, utilizing a variety of molding equipment
ranging from manual to fully automated and mechanized.  The
principal exceptions to this are those foundries producing
cast iron pipe by pouring metal into rotating metal molds and
those using rotating or stationary permanent molds.  Although
a large tonnage of iron is produced in the pipe foundries,
there are relatively few such foundries by comparison with the

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                                                     Ill - 10
total number of iron foundries.  There  are approximately 35
foundries in this category who produce  about 20% of total iron
foundry production.
     The remaining iron foundries, with few exceptions, use
sand as a molding material,  and  are  therefore equipped with
sand handling storage and conditioning  facilities; mold pour-
ing, cooling and shakeout facilities; casting cooling, cleaning
and finishing facilities; and, in many  cases, coremaking
facilities.   Because of the wide variety of types, arrangements,
sizes and utilization of the equipment  in these areas of the
iron foundry, it is  impractical  to attempt to classify or
tabulate facilities  in all of the foundries, and this has not
been done in this report.
     In general, the increasing  costs of labor, and the prob-
lems of recruiting and training  foundry labor, have resulted
in a trend toward mechanization  as a means of reducing the
labor content in iron casting costs.  An increasing number
of iron foundries are installing continuous or mechanized
molding lines,  sand  preparation, casting cleaning, coremaking,
and other facilities.   This  trend, which increases the facilities
cost in the foundry, has also been a  factor in the continuing
reduction in the number of small foundries.
                                                       Ill - 11

BASIC CHARACTERISTICS
  OF THE IRON FOUNDRY
  INDUSTRY	
Compilation of
  Foundry Data
     The large number of  iron  foundries  in  existence,  reported
to be 1,670 in 1969, and  the general  lack of detailed  informa-
tion on each of these foundries made  impractical  a complete
detailed tabulation of data on every  foundry.
     Detailed information on approximately  170  foundries,  10%
of the total number, is compiled  in a data  bank included in
Appendix B.  The nature of the data compiled includes:
          1.  Coded identification of foundry.
          2.  Type and number of  furnaces.
          3.  Melt rate of each furnace.
          4.  Type of air pollution control equipment  on the
furnaces.
          5.  Collection efficiency of the  air  pollution con-
trol equipment.
          6.  Types, capacities,  and  number of  molding,  sand
conditioning, coremaking, shakeout, cleaning, painting,  and
other emissions producing equipment.
          7.  Emission test data  resulting  from stack  testing
done at the foundry where available.
     Because of the confidential nature of  some of  the informa-
tion which was provided by many companies,  all  of the  foundries
are identified by a code number so that the  information  is
presented on a basis of non-identification with any individual
company.

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                                                       Ill - 12

In-Plant Foundry
  Visits	
     Pace of the information for the data bank was developed
from in-plant foundry visits made in 1970 by A.  T. Kearney &
Company, Inc. and also in 1967 as a part of a survey made
jointly by the Department of Commerce and NAPCA.  A total of
approximately 100 foundry visits was made in these two surveys.
The purpose of the visits was twofold:
          1.  To obtain emissions data to be used in a mathe-
matical analysis that will identify the effect of certain
design and operating variables on the type and quantity of
particulate emissions.
          2.  To obtain firsthand reports from users of control
equipment as to the effectiveness, and the operating or main-
tenance problems experienced with different types and manufacture
of equipment.

     A careful analysis of iron foundries in the United States
was made to insure that the total emissions data collected
reflected, to the degree possible, the effects of all identified
variables in the melting systems design and operation.  The
steps preliminary to the selection of foundries  to be visited
were based on an analysis and classification of melting
facilities, which is described in detail in Section VI.

THE AIR POLLUTION
  PROBLEM	
     The pollutants discharged by the iron foundry industry
can be classified as:
          1.  Emissions from melting furnace operations.
                                                       Ill - 13

          2.  Emissions from other dust-producing operations
within the plant.
          3.  Odors and gaseous compounds  from both  sources.
     Exhibit III-7 has been prepared to identify the principal
sources of emissions in iron foundries and to indicate  the
types of emissions which are produced in each.  A more  detailed
description of these processes, the emissions produced,  and the
methods of collection and control will be  found in subsequent
sections of this report.

     The physical difficulties of satisfactory collection of the
emissions are not easily solved and, in most cases,  costs of
satisfactory collection are quite high.  Gases from  foundry fur-
naces are hot and must be cooled before collection.  If  recircu-
lated water is used for cooling and dust collection, corrosion
problems may be introduced.  Cost of fresh water is  high, requir-
ing recirculation in most cases.  Most metallic oxides  from melt-
ing operations are extremely small in size and require  very effi-
cient equipment for collection.  In some cases, condensed metals
present explosive hazards which must be considered.

     Particulate emissions have been a point of focus for concen-
trated efforts in the control of air pollution.  However, gaseous
emissions and odors from the foundries have not been given much
attention, and the foundry industry now has to take steps to sup-
press these discharges into the atmosphere.  Most of the odors  xn
foundries result from core baking and shell molding operations,

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                                                        Ill - U
but the common gaseous emissions also include vapors  from melting
oily metal scrap, painting operations, inoculation  of metal,  and
from metal pouring into molds.

     Air pollution control equipment has been generally  considered
a nonproductive expense, involving a major investment on the  part
of the industry without benefit of payback.   The  operation and  the
maintenance costs can be high and the equipment is  generally  con-
sidered to have a relatively short life.  All these factors have
an effect on the selection of the type of equipment to be used  in
a foundry installation and usually require a high level  of man-
agement decisions.

     These factors, which represent the nature of the air pollu-
tion problem for the iron foundry industry, indicate  the need for
a detailed study of the problems facing the iron  foundry industry
and development of technology for control of air  pollution from
these  sources at reduced cost.
                                                                                                                                     Ill - 15
                        REFERENCES

     1.  Foundry Magazine. "Foundry  Census," July,  1970,
pp. 94-5.
     2.  U.S. Dept. of Commerce.  "Iron  and  Steel  Foundries
and Steel Ingot Producers, Summary for  1968," July,  1970.
     3.  Foundry Magazine. "Inventory of Foundry  Equipment,"
1968, 1960, 1954, 1957.

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                  IV -  DESCRIPTION OF BASIC
                  	FOUNDRY PROCESSES
INTRODUCTION
     The Iron foundry consists of a number of distinct but
strongly interconnected operations.  All foundries  utilize
certain basic operations consisting of:
          1.  Raw material storage and handling.
          2.  Melting.
          3.  Pouring into molds.

     Other processes present in most, but not all,  foundries
include:
          1.  Molding.
          2.  Sand preparation and handling.
          3.  Mold cooling and shakeout.
          4.  Casting cleaning, heat treating, and finishing.
          5.  Coremaking.
          6.  Pattern making.

     A  simplified, schematic flow diagram encompassing most of
these processes is presented in Exhibit IV-1.

     Each operation contains equipment and processes capable
of producing emissions  which may  include gas, fume, smoke,  vapor
and particulate matter.  The latter  can range from metal dust
from grinding operations,  that is  relatively easy and in-
expensive to collect, to extremely fine ferrous and nonferrous
oxides  from melting  furnaces that  are  very expensive and
                                                                                                                                          IV - 2
difficult to collect.  The sources of these emissions  are
schematically indicated in Exhibit IV-1, and the operations  are
described in the following paragraphs of this report.

PROCESS FLOW FOR
  CRAY, DUCTILE AND
  MALLEABLE IRON
     The basic process flows for gray, ductile, and malleable
iron are shown in Exhibit IV-2.  In general the flow is  similar
for each of the three types of iron, except for the variations
shown in the exhibit.

     The most common flow pattern in the iron foundry  industry
is the one for gray iron production.  The process  flow for
ductile iron differs from gray iron principally by the addition
of two operations—the magnesium treatment to nodularize the
graphite in the iron and the press straightening which is
sometimes required.

     Malleable iron process flow is also similar to gray iron
flow with the exception of an annealing operation  required  to
convert the as cast "white" iron into malleable iron,  and the
press straightening sometimes required to correct  the  warping
that results from the annealing process.  In other regards  the
process flow for malleable iron is the saute.

     Specifications for various classes of gray, ductile, and
malleable iron are tabulated in Exhibits IV-3, IV-4, and IV-5.

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                                                      IV  -  3
PROCESS FLOW AND DESCRIPTIONS
  OF BASIC FOUNDRY OPERATIONS
     Detailed process flow diagrams  for each of  the basic iron
foundry production operations are depicted in referenced exhibits,
except for cupola melting.   Heat and material balances for cupolas
are included in Appendix C with a description of the mathematical
model developed for calculating the  heat and material balances.
Brief descriptions of the operations are given on the following
pages.  More detailed information on the basic operations can be
obtained from referenced sources.

Raw Material Storage
  and Furnace Charge
  Preparation	
     (a)  Raw Material
     	Receiving and Storage
     The raw materials used for iron production  fall into Che
following classifications:
          1.  Metallics:
              (a)  Pig iron.
              (b)  Iron and steel scrap.
              (c)  Turnings and borings (loose or briquettes).
              (d)  Ferroalloys.
              (e)  Foundry returns.
              (f)  Alloys such as  nickel, copper, tin and
                   magnesium.
          2.  Fluxes:
              (a)  Carbonate type  (limestone, dolomite, soda
                   ash).
              (b)  Fluoride type (fluorspar).
              (c)  Carbide  type  (calcium carbide).
                                                                                                                                           IV - 4
          3.  Fuels-Coke (for cupolas).
          4.  Refractories.
     These materials, except for foundry  returns,  are received
by railcar or truck, and are unloaded and stored  in the foundry
scrapyard.  Although open scrapyards are  still  common,  the use
of covered storage areas is becoming more widespread to reduce
che rusting of ferrous scrap and the weathering and degradation
of coke and limestone.  Covered storage is also desirable for
induction melting scrap which must be dry when  charged  into the
furnace.  Scrap metals, pig iron, and foundry returns are usually
stored in piles which may be unconfined, but are  often  separated
by walls to form open bins.  Coke and stone may also be stored
in piles, but are commonly stored in confined bins  to facilitate
charge makeup.
     There are no industry standards for  foundry  coke.   Size
classifications up to 6" x 8" are available depending on the
requirements of each foundry.  The range  of proximate analysis
values for foundry coke are as follows:
          Volatiles       0.77. - 1.257.
          Ash               4% -   12%
          Fixed Carbon     867. -   95%
          Sulfur          0.5% -  1.0%
Specifications for ferrous scrap metals are tabulated in
Exhibit IV-6.  Pig iron and commonly used ferroalloy specifica-
tions are shown in Exhibit IV-7.

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                                                      IV - 5

     (b)  Scrap Preparation
     For Che most part, scrap materials, including  foundry
returns, are used In the as-received  form.  Many scrap dealers
prepare scrap to foundry specifications, thus  eliminating any
need for additional preparation by the  foundry.  Where scrap
preparation la required, the operations may involve any  com-
bination of the following:
          1.  Cutting to size by flame  torch,  shear,  breaking,
or fragmentizing.
          2.  Cleaning by degreasing, by steam or by  shot-
blasting.
          3.  Burning of surface coatings  or  oils.
          A.  Drying or preheating.

     With the exception of the cutting  operations,  scrap
preparation is not widely performed for cupola melting,  or  for
top charged electric arc furnaces.  However,  for electric in-
duction furnaces, a greater degree of preparation  is  necessary
to obtain dry, clean scrap of Che proper size.

     (c)  Furnace Charge
     	Preparation
     The methods of makeup and handling of melting furnace
charges vary widely from completely manual systems  where all
materials are hand shoveled or carried, to highly  mechanized
systems where one man can control the handling, weighing, and
loading of  all rav materials.
     Charges are normally loaded directly  into the furnace
charging bucket, skip, or similar container.   The  prescribed
                                                                                                                                            IV -  6
combination of metallics, flux, and coke  (for cupolas)  is  weighed
either before loading or while loading.

     Where preheating or drying operations are performed,  they
are commonly done directly in the charge containers.  This can
be accomplished by heating from above with a  flame  or radiant
burner, or by use of a double-walled bucket in which combustion
is accomplished within the wall cavity.  Other methods  include
the use of rotary dryers, heated conveyors, and preheat  furnaces.
Process flow for scrap preparation and change makeup is  shown
in Exhibit 1V-8.

Iron Melting
     The process flow in the foundry melting  department  is
depicted in Exhibit IV-9.  Four types of melting  furnaces  rep-
resenting over 98% of the installed melting systems are
considered in the flow diagram.  A 1968 study, covering  about
75% of all foundries, showed the following distribution  of
melting furnaces in the iron foundry industry.
           Iron Foundry Melting Furnaces - 1968
Furnace Type
Cupola
Electric Induction
Electric Arc
Other Types
Total
Number Installed
1,232
73
42
29
1 .376
Percent of Total
89.5%
5.3%
3.1%
2.1%
100.0%

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                                                       IV - 7
     The furnace census does  not show  the number of reverbera-
tory furnaces In use, but it  would be  expected that they
constitute the majority of the 2.U  indicated as "Other Types."
Despite the low incidence of  use, this method of melting is of
interest because of its reported  low emission of particulate
matter, and its increasing use in small  foundries.
     The process flow diagram shows  the  metallic and flux
materials charged into each type  of  melting  furnace.  The
reverberatory furnace is heated by coal, natural gas or oil,
while the induction and arc furnaces obtain  their heat from an
electric induction coil or an electric arc.  In the cupola,
coke is a portion of the furnace  charge  and  the heat required
to melt the iron is derived from  the combustion of the coke
in contact with the metallic and  fluxing charge materials.
     The molten metal from the furnaces  is tapped directly into
a ladle for direct mold pouring,  into  a  transfer  ladle for
conveying to the molding area, or into a heated or unheated
holding device.
     From a cupola, the hot metal can  be transferred to a
forehearth, or an electric induction or  arc  furnace for holding,
or  into a reverberatory duplexing furnace  if the  final product
is  to  be malleable iron.  With the exception of the forehearth,
a similar selection of holding or duplexing  furnaces is avail-
able for electric or  fuel fired melting  furnaces.  As the metal
is  available and required, it is  removed from  the holding or
duplexing  furnaces for transfer to the molding area.
                                                                                                                                          IV - 8
     (a)  Cupola Furnaces
     The cupola is a vertical furnace with  a  normally  circular
cross section which is charged alternately  with  metal  to be
melted, fuel in the form of coke, and a  fluxing  material,  to
produce molten iron of a specified analysis and  temperature.
Many fundamental cupola designs have evolved  through the years,
two of which are widely in use at this time--the conventional
refractory lined cupola and the more recent development,  the
unlined, water-cooled cupola.
          1.  Conventional Lined Cupola.  For all cupola designs,
the shell is made of rolled steel plate.  In  the conventional
design, an inside lining of refractory material  is  provided to
protect the shell from the operating temperature.   The cupola
bottom consists of two semicircular, hinged steel doors,
supported in the closed position by props during operation,  but
able to be opened at the end of a melting cycle  to  dump the
remaining charge materials.  To prepare  for melting, a sand bed
6 to 10 inches deep is rammed in place on the closed doors  to
seal the bottom of the cupola.
          Combustion air is blown into the  wind  box, an annular
duct surrounding the shell near the lower end, from which it
is piped to tuyeres or nozzles projecting through the  shell
above the top of the rammed sand.  The tap  hole  through which
the molten iron flows to the spout is located at  the level
of the rammed sand bed.   For nearly all continuous  tap operations,
the slag also is discharged through the  tap hole  and separated
from the iron by a skimmer in the runner.   For intermittent

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                                                      IV  - 9

capping, molten Iron collects  in  the well with the slag  float-
ing on its surface, and a slag hole is  located at the  level
representing the height of the maximum  amount of iron  desired
to collect in the well.  An opening is  provided in the cupola
shell 15-25 feet above the bottom plate for  charging the cupola.
The charging door opening varies  in size according to  the  in-
tended method of charging and the diameter of the cupola.  The
upper stack is extended sufficiently to pass through the building
roof and provide the required, natural draft. On open  top  cupolas,
a spark arrester is fitted to the top of the stack to  reduce
the hazard of fire.
          The shell of a conventional  lined cupola  is  protected
with a  refractory  lining.  The lining  is usually  built up  using
high-duty fireclay shapes for acid melting and magnesite shapes
for basic melting.  An Illustration of a typical  conventional
lined cupola is depicted in Exhibit IV-16.
          2.  Water-Cooled Cupola. The unlined,  water-cooled
cupola  utilizes a  steady flow of cooling water  on the  outside
of the  unlined shell generally from below  the charging door to
the tuyeres, and an inside lining of carbon blocks  below the
tuyeres  to the sand bed, to protect the shell  from the interior
temperature.  Conventional lining is used  at the  charging
door level and in  the upper stack.  In other regards,  the  water-
cooled  cupola is essentially the same  as the lined  cupola.
Exhibit  IV-17 shows two types of water-cooled cupolas.
          3.  Blast Air.  Combustion air is  supplied  to  the
cupola  in appropriate amounts depending upon the  desired melting
rate and the size of the coke charge,  at a  pressure  related to
                                                       IV - 10

the volume and height of the burden.  The air is piped from the
blower, which can be a centrifugal or positive displacement
type, to the wind box, and thence to the tuyeres, spaced equally
around the cupola shell.   In a normal design, a single row of
tuyeres is used.  In the balanced blast cupola, the blast air
is divided between three rows of tuyeres with the provision for
adjusting the flow of air through each tuyere.  Varying the flow
in a regular sequence prevents bridging of the charge at the
tuyere and results in greater combustion efficiency and higher
melting rate.
          The temperature of the blast air has a strong effect
on coke requirements, melting rate, and cost of melting.  The
heat supplied by warm or hot blast decreases the BTU's required
from the coke and therefore permits the coke charge to be de-
creased, or the melting rate to be increased.  Where the cost
favors natural gas or oil over coke, the heating of the blast
air with these fuels can lower the cost of melting.  Early
efforts at heating the blast air resulted in temperatures of
300°-400° F.  Later, temperatures of 1000°-1200° F were used
successfully and, recently, a successful installation with
1800° F blast air has been reported.
          Most air preheater installations in the United States
are externally fired, although many attempts have been made to
successfully recover the latent and sensible heat of the cupola
with varying results.  Some of the problems in developing
successful units were maintaining the heat exchanger, keeping
the heat transfer surfaces clean while passing dirty gas through

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                                                      IV  -  11
them, and designing a system low enough  in cost to make the
installation economically feasible.
          4.  Fuel Injection.   Numerous  attempts have been made
to inject coal, oil, or gas into cupolas to  replace a portion
of the coke required to melt the iron.   Successful results have
been reported for natural gas injection  resulting in  lower
melting costs.  No tests using coal  or oil have been  reported
in recent years.
          5.  Oxygen Enrichment.  A  number of  foundries are
injecting oxygen into the cupola with resulting increased melt-
ing rates.  One potential advantage  of this  technique is that
the stack gas volume is decreased, since the oxygen used for
combustion does not carry with it the inert  volume of nitrogen
found in air.
          6.  Closed Top Cupolas.  In either recuperative hot
blast cupolas, or where there  is a requirement that cupola
stack gases be cleaned before  releasing  them into the atmosphere,
the normal practice is to close  the  top  of the cupola and draw
the gases off either just below  the  cap,  or  below the charging
door.  If collection is above  the charging door and the door
is always open,  air is infiltrated through the opening sub-
stantially increasing the volume to  be handled, and therefore
increasing the cost of the control system.   If the door is
normally closed, the infiltrated air volume will be lower but
oxygen present in the gases  may  be insufficient to bum the CO
to CC^.   A compromise is sometimes reached where doors are
provided that permit infiltration of enough air to aid in
complete combustion of the CO.
                                                                                                                                             IV  -  12
          7.  Afterburners.  The cupola  gas  rising  from the
top of the burden is rich in carbon monoxide.  When mixed with
air infiltrated through the charge door  opening,  this  gas
becomes a combustible mixture and it is  desirable that it be
ignited at this point.  Combustion normally  occurs  here because
of the gas temperature, but the flame is sometimes  extinguished
when the charge is discharged from the charging bucket.   To
assure reignition, a gas torch, or afterburner, is  often
installed in the cupola just above or below  the charging door.
The afterburner performs the additional  function  of incinerating
oil vapors, coke particles and other combustibles.
          8.  Cupola Operation.  At the  beginning of the melt-
ing cycle, a coke bed is placed on the rammed sand  bottom and
ignited, preferably with a gas torch or  electric  igniter.
Additional coke is added to a height of  four or five feet above
the tuyeres after which regular layered  charges of  metal,
limestone and coke are placed on the coke bed up  to the normal
operating height.  Typical cupola charges for gray,  ductile,
and malleable iron are included in Appendix  C.  The air blast
is turned on and the melting process begins.  As  the coke is
consumed and the metal charge is melted, the furnace contents
move downward in the cupola and are replaced by additional
charges entering the cupola through the  charging  door.
          As the metallic charge moves downward,  it is preheated
by the hot gases resulting from combustion.  These  gases con-
sist of carbon monoxide, carbon dioxide, nitrogen,  hydrogen,
and sulfur dioxide, the latter principally from the sulfur

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                                                       IV - 13
contained in che coke.  Aa the metal enters the melting zone,  the
atmosphere is of a highly reducing nature with no free oxygen.
The molten iron, trickling down over the incandescent coke and
increasing in temperature, reaches the combustion zone where the
atmosphere becomes oxidizing in nature, due to the presence of
oxygen from the blast air.  In this part of che cupola, the
iron reaches the desired tapping temperature.
          Blast air entering the cupola through the tuyeres
contains 21% oxygen which combines quickly with the carbon in
the coke as follows:
          C + 02-» C02 + 175,900 BTU/pound mole
The oxidizing zone in which this reaction occurs is designated
the combustion zone.  It is the zone of highest temperature and
extends from the tuyeres to a level where the  following reaction
occurs:
          C +• 2 -» 2 CO - 69,700 BTU/pound mole
The reduction of C02 to CO starts before all oxygen in the
blast air is consumed.  The maximum COj concentration is be-
lieved to be approximately 147.-187. at the boundary of the
oxidation and reduction zones at a maximum temperature of 2,800°
-3400° F.  Both reactions noted are reversible and proceed in
both directions depending upon conditions at different levels.
The reactions almost cease in che preheat zone as  energy is
used to preheat the charge materials and the gas temperature
ia lowered to the reaction temperature  below which further
reduction of carbon dioxide to carbon monoxide will not occur.
A pictorial description of a cupola reaction area  is  shown in
Exhibit IV-IB.
                                                        IV -  W
          '•  Cupola Furnace Operations  Model.   Approximately
300  iron  foundry melting systems  in  the  United  States  are
currently equipped with some type  of air pollution  control
equipment, ranging from wet caps to  fabric  filters, wet
scrubbers, and electrostatic precipitators.  A  detailed  investiga-
tion of about 170 of the cupola systems  included in this  total
showed that they could be characterized  by only 32 classifica-
tions, each one representing a specific  combination of cupola
design factors.
           In Appendix C,  the heat and material balances  for each
class are tabulated and the classifications are depicted
pictorially.  The heat and material  balances were derived by
the use of a computerized mathematical model designed  to  cal-
culate these balances for a given  set of cupola operating
conditions.  Input data were obtained from the  records of about
50 foundries visited in 1970 and from test data  In  the files
of various city and state air pollution  control boards.   Details
of the computer program developed  to make the calculations are
included in Appendix C.
           In addition to the description of the heat  and
material balance model, Appendix C includes the following data:
              ~  Specific Inputs Required for the Model.
                 Input data required tor the calculations
                 are tabulated.
              -  Chemical Reactions  Considered  in the
                 Model.Chemical  reactions considered to
                 have a qualitative  and  quantitative effect
                 on emissions produced in a cupola used
                 to produce iron are listed.
              -  Material and Heat Balance Relationships
                 Considered in the Model'.  Theoretical and
                 empirical material balance relationships
                 upon which the model is based are listed.
                 Similar relationships for the heat balance
                 calculations are  shown.

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                                                      IV - 15
                 Sample Outputs  for Material and Heat
                 Balances.  Sample outputs for material
                 and heat balances are included in the
                 appendix.  The  appendix indicates the
                 format of the computer output.  Material
                 balance inputs  are acceptable either in
                 pounds of charge materials or a percentage
                 of total charge weight.  The model cal-
                 culates the balance and prints the outputs
                 in pounds per ton of molten iron.
                 Heat  balance outputs are printed out in
                 thousands of BTU s per hour.  The pro-
                 gram  also computes the volume of the top
                 gases, and a theoretical analysis of the
                 stack gases including air infiltrated
                 through the charging door if the input
                 indicates that  the cupola is operated
                 with  the door open.
                 Composition of  Materials.  To simplify
                 the computation, the model makes use of
                 standardized material compositions for
                 metallic charge materials and products,
                 fluxes, coke ash, and cupola refractory
                 linings.
     (b)  Electric Arc
     	Furnace
          1.  Description.  The direct arc electric furnace
consists of a refractory  lined, cup shaped, steel shell with
a refractory lined roof through which three graphite or carbon
electrodes are inserted.  The  shell is arranged for tilting to
discharge the molten metal.  Charging of the metal is accom-
plished by chuting through  a door  opening in the side of the
shell, for fixed roof furnaces, or by raising  the roof and swing-
ing it aside to permit  the  use of  a bottom dump charge bucket
for removable roof furnaces.   Foundry size furnaces generally
range in diameter from  about 3'0"  to 12'9" with holding capa-
cities of 500 pounds to 25  tons, and melting rates from 250
                                                                                                                                             IV - 16
pounds to 12 tons per hour.  Larger furnaces have  recently been
installed for melting iron, one large  production foundry having
recently put into service a 65-ton capacity arc furnace  with
a melting rate of about 22 tons per hour.  For iron melting
with light scrap, the inside depth of  the  furnace  is  approximately
757. of the inside diameter.  Furnace shells are of welded con-
struction, often with a water-cooled section at the top  edge.
The furnace roof is provided with a circumferential water-cooled
ring, and water-cooled electrode glands.   Tilting  mechanisms
are mechanical or hydraulic, the latter  being of later and more
satisfactory design from the standpoint  of precise controllability.
The furnace is provided with a  tapping spout and a working door,
with a second door for large furnaces.
          The electrodes, supported by water-cooled holders,
are provided with a hydraulically or mechanically  operated
raising and lowering mechanism  to maintain the arc, especially
during meltdown.  The electrodes and roof  on a top charge
furnace are supported Independently from the shell and are
arranged to permit raising to clear the  shell and  rotating to
one side for charging.
          A transformer vault adjacent to  the furnace is re-
quired to house the current and potential  transformers,  circuit
breakers, high and low voltage  wiring, low voltage bus bars,
secondary furnace cable connections, and instrument panel.  A
control panel and operator's console are required  near the
furnace.  Multi-voltage, tap charger transformers  are used to

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                                                      IV -  17
make voltage changes as necessary during the  melting  cycle.
          The furnace bottom refractory lining can be either
acid with a rammed ganister mix over silica brick, or basic
with a rammed magneaite mix over silica brick, although acid
lined furnaces are generally used for melting iron.  Sidewall
lining is generally a high alumina fire brick.  The bottom
lining is subjected to abrasion and crushing during charging,
but commonly  remains serviceable for months.  The sidewall is
subjected to  both abrasion and the effect of the molten iron
and slag and  requires  patching between heats.  The roof lining
made  of  high  alumina brick is subjected  Co high temperature and
effects  of  metal and slag splatter from  the arc.  A  typical
electric arc  furnace with supporting equipment is  illustrated in
Exhibit  IV-19.
           2.   Electric Arc Melting.  For top  charge  furnaces,
 the charge materials are usually weighed into  bottom dump buckets.
 When charge preheating is  used,  the  heating  may  be accomplished
 in a specially designed, refractory  lined bucket,  a  double
 walled bucket, or the  charge transferred to  a preheating chamber,
 and then moved to the  furnace.   A cost-saving potential exists
 in preheating the charge in the charge bucket, by substituting
 a lower cost fuel to raise the charge temperature to 1200°-
 1400° F.
           In charging a side charge furnace, the metal charge
 is often weighed Into a trough-shaped bucket, which  is trans-
 ferred  to  the furnace and tilted to permit the charge materials
 to slide into the furnace door opening.  When using  the arc
                                                                                                                                            IV  -  18
furnace as a hot metal holder, the hot metal from the primary
melter can be transferred to the arc furnace by  ladle, or  by
refractory lined launder, and discharged into the charging
opening.
          Exhibit IV-10 shows the composition of a typical
charge, heat, and material balance.  The carbon  required in
addition to the carbon content of the scrap is derived from
the petroleum coke added to the charge and from  the electrode
material consumed during the melting cycle.  Since there is no
coke ash requiring fluxing as in the cupola, only small
quantities of flux materials are needed.  Chemical reactions
occurring within the furnace also are few compared to the
cupola, since there is little combustion.  The fume generated,
particularly at the start of meltdown, is the result of locally
intense heat caused by arcing of the electrodes  before a molten
pool of metal is formed.  Oxides of iron and other elements
contained in the charge materials are formed at  this time,
                                 4
by vaporizing some of the charge.
          3.  Indirect Arc Furnace.  The indirect arc or rocking
arc furnace is more commonly used for nonferrous and high  alloy
melting than for iron melting, but is found in many smaller
iron foundries.  It consists of a refractory lined horizontal
drum which rotates about its longitudinal axis for charging
and tapping.  One electrode is located in each end, with the
resultant arc being struck above the charge, resulting in
melting from an indirect arc as contrasted with  the direct arc

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                                                        IV -  19
in the more commonly used arc furnaces.  These  furnaces  are
builc only in small sizes, from a few hundred pounds  Co  four-Con
capacities.
     (c)  Induction Furnaces
          1.  Description. The induction  furnace  is  a cup- or
drum-shaped vessel that converts electrical energy into  heat to
melt the charge.   Unlike the  electric arc  furnace, no electrodes
are required.  The induction  furnace converts electrical energy
into heaC by utilizing Che transformer principle in which a
magnetic field is set up when the primary  coil  of  the transformer
is energized.  The magnetic field at a high flux density induces
eddy currents in the charge which are converted to heat  by the
electrical resistance of the  charge  itself.
          The heat is developed mainly in  the outer rim of the
metal in the charge, but is carried  to the center  by  conduction
until the metal is molten. The electrical energy  is  converted
into heat by induction in two ways.   In the channel induction
furnace, the metal charge surrounds  the transformer core,
thereby forming a loop or channel.   In the coreless induction
furnace, the metal heated is  both the core and  secondary coil.
Furnace coils are water-cooled to prevent  heat  damage.
          The amount of heat  developed in  the furnace is a
function of the electrical current frequency  and the  intensity
of the magnetic field.   Theoretically, there  is no limit to the
temperature attainable; however,  a practical  limit exists due
to material limitations such  as refractory lining of  the furnace.
                                                                                                                                     IV  -  20
At present, commercial linings are available  for temperatures
somewhat over 3000° F.
          2.  Operating Characteristics.  The  induction furnace
lends itself to either semicontinuous or  batch-type  operations
and can be used as a melting furnace or for holding  or duplex-
ing operations.  Generally, the coreless  furnace is  better
adapted to melting and superheating, whereas  the channel furnace
is better suited to superheating, holding, and duplexing,
although it is also sometimes used for melting.   Exhibits  IV-20
and IV-21 illustrate channel and coreless induction  furnaces.
          Coreless furnaces are available in high, medium  and
low frequency types.  Installations for iron melting and hold-
ing are generally limited to the low or line  frequency of  60
cycles, and medium frequencies of 180 cycles.
          The coreless design permits melting  of a cold charge for
each cycle, allowing frequent analysis change.   The  energy is
constantly induced into the entire charge so that temperature
differentials within the melt are minimal.  This is  not the
case in a channel induction furnace where energy is  induced
only in the molten metal actually in the channel.  Despite
the ability of the coreless furnace to melt cold charges,  most
production foundries maintain a heel of molten metal in the
furnace to increase efficiency and lower thermal shock to  the
refractory lining.  The scrap charge must be dry for this
method of operation to prevent explosions that would result
from addition of moisture to a molten metallic bath.

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                                                       IV - 21
          3.   Charging.   Melting losses are low and  the  recovery
of alloying additions Is  high In induction melting of gray  iron.
The charge may consist of a single lump of metal, a  number  of
small pieces  of selected  scrap,  or even turnings.  Charges  are
usually made  up of steel  scrap,  cast iron scrap,  foundry returns,
and ferrosilicon and carbon in suitable quantities to adjust
composition.   Pig iron is seldom used.   Turnings  and borings
are readily melted in a coreless furnace, although care  must
be taken to avoid oxidation before melting has  occurred.
          When available, turnings or borings can comprise  up
to 20% of the charge in a coreless furnace.  Carbon  adjustment  is
accomplished  by the addition of pelletized coke.  Preheating of
the charge is considered  beneficial from the standpoint  of  re-
moving moisture and oil as well as reducing melting  costs and
shortening the melt cycle.
          Charge materials are commonly weighed into a bottom
dump charging bucket, although small furnaces can be charged
manually.  In some cases, the charge is collected in pans placed
on the working platform and is dropped into the furnace  either
by tipping the pan or by  raking the pieces out  of the pan and
into the furnace.  Charging into the furnace is from the top.
Additions of carbon and ferrosilicon are made directly into
            it
the furnace.
          4.   Melting. The induction furnace is basically
a batch melter.  Continuous melting is possible with a recently
developed coreless furnace and approximated in  the conventional
design by partial tapping of a melt followed by a makeup charge
of cold scrap.
                                                        IV - 22
          A strong stirring action from electromagnetic  forces
is exerted on the molten bath in a coreless furnace.  The
stirring action helps to obtain a homogeneous melt when  ladle
additions for carburizing and analysis correction are made.
The mixing action is less in a channel-type furnace.
          The analysis of the iron from induction melting is
highly reproducible due to the general lack of unpredictable
or undesirable reactions in the furnace.  Induction melting
does not alter the chemical composition of the molten metal
from the original charge.  However, since it is not a refining
process, care must be exercised in the makeup of the charge.
The process flow for coreless induction melting is shown in
Exhibit IV-11.
          Induction furnaces are more efficient superheaters
than cupolas or arc furnaces.   For this reason, high tapping
temperatures are more practical with coreless and channel
induction furnaces, and these units are often used for super-
heating, and where hot metal must be held for an extended period
of time, induction furnaces have been used for feeding automated
casting lines with the metal being tapped as required, and
often held at pouring temperature when molding is delayed for
some reason.
          5.  Furnace Sizes.  Coreless induction furnaces are
found in an extremely wide range of sizes, from under 100 pounds
capacity, to recently designed installations of 70 tons  and
larger.  Similarly, channel induction furnaces vary widely in
size, from a few hundred pounds to 260 tons in holding capacity.

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                                                       IV  - 23
Power inputs range from under 100 kw,  Co 17,000 lew  for coreless
furnaces, and up to 4,000 kw for channel furnaces.
     (d)  Reverberatory
     	Furnace	
     The reverberator? type of fuel  fired  furnace is found in
two types of applications in the iron foundry.  The large,
stationary reverberatory or air furnace  is associated with
malleable iron foundries, where it has long been used as a
duplexing unit in conjunction with a cupola.  These furnaces
are generally powdered coal fired, although oil and gas are
also used.  Host are not melters, but are used to receive
molten iron from the cupola, and to  refine and superheat it
for pouring.  These furnaces are long, rectangular units with
arched or suspended roofs, generally fired from one end, and
with waste gases exhausting into a stack from the opposite
end.  Temperatures of 2900° F and higher are reached in these
furnaces.  Holding capacities range  up to 40 tons. *    A
typical furnace of this type is shown in Exhibit TV-22.
     the second type of reverberatory fuel fired furnace is
used for melting.  It is generally small in size, up to two
tons capacity, and tilts for pouring.  Furnaces of this  type
are found in small foundries, where  economical installations
and low emission melting are desired.

Inoculation
     Inoculation is a process applied either in the production
of -ductile iron, where it is known as magnesium treatment, or
                                                                                                                                        IV - 24
 to improve the mechanical properties of castings.
                                                                                      (a)   Ductile Iron
                                                                                     	Production
       In the production of ductile iron, agglomeration of
 spheroidal graphite is accomplished by treatment of the base
 iron while in the ladle.   A number of inoculating agents in-
 cluding  magnesium,  calcium, cerium, and yttrium are suitable,
 although magnesium is  most widely used.  The relative economics
 and availability  of these  materials have resulted in the common
 use of magnesium  for this  purpose.   Many techniques have been
 developed to place  the inoculant  in the molten iron using
 magnesium in the  pure  form, in  a  variety of alloys, and im-
 pregnated in coke.   No single form has been universally accepted,
 although  nickel-magnesium,  copper-magnesium,  magnesium-silicon-
 iron, nickel-silicon-magnesium  alloys, and magnesium impregnated
 coke are  frequently  employed.   The  speed and  violence of the
 reaction  is  due in part to  the  concentration  of magnesium in the
 alloy or  coke.  Some of the treatment  techniques used to produce
                                         g
 ductile iron are shown  in Exhibit IV-23.
      (b)  Improvement of
      	Mechanical Properties
      The inoculation process is applied to molten  gray  iron
to obtain a desired shape, size, and distribution of graphite
in the finished casting.  The effect of an inoculant depends
on the type and amount used, the temperature and condition of
the molten iron at the time of addition, and the amount  of time
that elapses between inoculation and pouring.

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                                                       IV  -  25

      Inoculants contain various  amounts  of carbon, silicon,
chromium, manganese,  calcium,  titanium and other elements.
Inoculant effects include decreasing chill depth and increasing
tensile strength.

      An inoculant can be introduced Co the molten metal in  the
cupola spout, forebearth, transfer  ladle, pouring ladle or mold.4
Duplexing
     Where large tonnages are  needed,  or  where  a continuous
supply of molten iron Is required to  pour conveyorized  molding
lines, duplexing melting systems  are  often employed.  In duplex-
ing, iron is melted in one furnace, usually a cupola, and  refining
and temperature control are achieved  in a second furnace.  The
melter is continuously tapped  into  the second furnace (an  air
or electric unit) which is then tapped intermittently into
transfer ladles for pouring into  molds.  The second furnace
accomplishes carbon adjustment and  serves to decrease analysis
variations of metal coming from the cupola.  Duplexing  is also
used In the production of malleable iron.

Molding, Pouring,
  Cooling and Shakeout
     Many molding materials and types  of  equipment have been
developed for the production of iron castings.  Techniques found
in current practice include green sand, dry sand, shell, hot box,
the full mold process, permanent  metal molds, and the Rheinstahl
process where stationary molds are  used with both lined and  un-
lined rotating molds  for centrifugal casting.
                                                        IV -  26
      Exhibit IV-12 illustrates the process flow for molding,
 pouring, and shakeout.

       (a)  Green Sand
            Molding,
       Of all the types of molding in use today, by far the
 greatest tonnage of castings is produced from green sand molds.
 They are commonly made of silica sand, clay, water, and  organic
 binders such as cereal binders mulled together to form a  moist
 mixture suitable for use with manual or automated molding
 machines and sand slingers.  Green sand molds are the  least
 costly of all molds to produce.

       A typical molding operation is done with the aid of jolt-
 squeeze draw machines.   The complete operation is often performed
 in two separate machines.   A jolt-squeeze-rollover-draw machine
 for drag molding and a  jolt-squeeze-draw machine for cope mold-
 ing are  used.   Holding  machines capable of molding cope and
 drag simultaneously in  one  molding  cycle are  also utilized.

       Mold production by a  single machine can also be performed
 by match plate  molding  machines or  on  an automatic molding line.
 In automatic molding lines,  the entire  green  sand  molding
 sequence is automatic with preset time  cycles.

      Very large green  sand molds, beyond the capacity  of con-
 ventional molding machines, are often made with a  sand  slinger.
This machine propels small amounts of sand Into the mold with
enough force to eliminate the need for machine jolting.

      Green sand molds are occasionally skin dried or air  dried
to produce better finish.   Drying removes moisture or other gas

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                                                        IV -  27

forming materials In che sand at the mold-metal  interface.
Molds which have to be akin dried are either faced with sand
mixtures containing thennosetting additives  or they  are washed
or sprayed with a refractory mold coating  to prevent metal
penetration.
     (b)  Centrifugal
    	Casting
    Cast iron pressure and soil pipe is normally made  in
permanent molds.  The molds are rotated rapidly  about  their
longitudinal, horizontal axis during che pouring and cooling
cycles producing a dense, high quality casting.   A dry sand or
shell sand core is inserted in the mold to form  the bell end of
the pipe only.   Cast iron pipe tannage represents approximately
20% of the total iron casting production.  Centrifugal casting
is also used for production of other types of castings, generally
of a symmetrical design.
    (c)  Dry Sand
         Molding
    Dry sand molding is usually applied to thick section
castings of fairly large size or weight such as machine beds,
cylinders, and heavy gears.   The sand mixes for this type of work
contain certain additives such as pitch, sodium silicate,
gilsonite, cereal, molasses,  dextrine, gluten, and resins.
These additives set at  the drying temperature employed, or by
chemical reaction with  curing agents, and produce a high dry
strength and rigid mold walls.
                                                        IV - 26

      In general,  dry sand molding Involves assembling the mold
 through the use of a number of parts of the mold which have been
 prepared using a  dry sand mix.  These smaller mold parts are
 prepared in the same type of equipment as used in green sand
 molding where  the dry sand mix is poured into the permanent metal
 mold  and compressed to form a section of the larger mold.  These
 sand  molds  are then baked in an oven where drying or baking takes
 place at temperatures of 300°-600° F.  After cooling, the baked
 dry sand molds are assembled to form the complete mold for the
 casting.
       (d)  Shell and Hot
      	Box Molding
      The shell molding process  for making castings is used
where dimensional accuracy  and surface finish of the part is
important.  This molding technique  has found  wide acceptance
in the foundry industry.  The sand  used consists of a mixture
of dry sand grains and synthetic  resin binder.   The resin muse
be a thermosetting type since the strength developed by Che mold
depends entirely on the strength of the binder  after the mold
has been heated.

      The equipment used for molding consists of a metal box
which houses the pattern plate and  is  heated  to a temperature
of 350° to 700° F.   The sand mix is  then blown  into this hot
box where the resin partially thermosets and builds  up  a coherent
sand shell next to pattern.  A mold  release agent  or a  parting
agent is necessary so that the ejector  pins can push the shell

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                                                      IV  -  29
off the patterns.   The cleaned shell  halves,  thus produced, may
be assembled and poured.   Shell molds may  require cores  and the
                                                          9
core setting is done prior to the assembly of shell  halves.

      (e)  Full Mold
      	Process
     The full mold process is a patented recent  development which
Involves the use of materials such as polyurethane or  polystyrene
foam to fabricate patterns where small runs  of complicated
designed castings are to be made.  In this process,  the  pattern
is either machined from a single block, or indivual  pattern pieces
are cut and then glued or fastened together.   These  patterns,  with
attached gating system, are then buried in sand.  Various cold
setting sand mixes are commonly used.  Some  work has been done
with unbonded sand.  Little success has been achieved  with green
sand since the ramming pressures deform the  patterns.  Metal  is
poured into the mold, vaporizing the  pattern and replacing it
with metal.  An advantage of full molding  is that pattern design
does not have to consider pattern removal  from the sand  since
each pattern is destroyed in the pouring process.
      (f)  Rheinstahl
           Proceaa
      Another recent development, the Rheinstahl process,  con-
sists of using cement as a binder and a fluidizing  agent  that
promotes a high density casting mix that results in a  cement-
bonded, fluid molding sand.  The fluidizer is  added to the sand
as it is being prepared in a muller or paddle-type  mixer.   The
                                                                                                                                    IV - 30
reported advantage of the Rheinstahl process is that ramming
time is practically eliminated since pouring can occur almost
                                             10
immediately after sand is placed in the mold.
      (g) Pouring and
          Cooling
      In a high volume production foundry, finished molds are
set out on continuous car-type or indexing mold conveyors, or
on pallet conveyor lines.  In smaller production and jobbing
foundries, completed molds are set out on the foundry floor
or on gravity roller conveyors.
      In mechanized production foundries  the molds  are  usually
poured within minutes of completion.  Most small  foundries,
however, may pour only a few hours a day, or only two or three
days a week.  In these cases the molds are usually set  out  on
the  foundry floor until  hot metal is available.   A pouring
station  in a mechanized  foundry  is illustrated  In Exhibit IV-24.

       (hi  Shakeout
       In many foundries  the casting  is separated  from the mold-
ing  sand manually.  Even in partially mechanized  foundries  where
completed molds are set  out on gravity roller conveyors for
pouring  and cooling,  the molds are dumped manually and  the
castings  picked or hooked  out of the sand and placed in a tote-
box  for  further cooling  and moving to the cleaning room.
       Larger and more mechanized foundries tend to use  a heavy-
duty vibrating screen for  shaking-out.  The  sand  flows  through

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                                                     IV -  31
the screen openings Co Che return,  or shakeout  sand  system,  for
transfer Co Che sand condicloning system.  The  cascings  are
removed from the shakeout grid manually,  by  a hoisC,  or  by action
of Che vibracing screen, for cooling and  sorting.  Exhibit IV-2S
shows a shakeout work sCat ion.

Sand Conditioning
      Sand is a basic foundry material used  in  substantial volume
by almost all foundries as a molding medium.  The complete sand
system consists of receiving and  storage  facilities, molding
sand preparation,  and the handling  equipment required to transfer
the sand to its points of use,  preparation,  and discard.  In
addition, some high production foundries using  very  large amounts
of sand have reclamation systems  for returning  used  sand to  its
original condition, or as near to it as is practical and
economical.
      The sand conditioning process flow  diagram is  given in
Exhibit IV-14.
      (a)  Receiving and
      	Storage	
      Raw materials requiring handling and storage after re-
ceiving include the silica sand and various additives such as
clay, carbonaceous materials, synthetic  resins, and cereal
binders.  In addition,  some foundries doing shell molding pur-
chase premixed shell sand.  Silica sand  is received by car or
truck, unloaded and conveyed manually, mechanically, or
pneumatically, and stored in covered areas or in enclosed bins
or silos.  Shell premix may be shipped in bulk or in multiwall
                                                                                                                                   IV -  32
bags depending  on  usage.   Solid  additives are received in bags
or  fiber drums,  and  liquid additives  in metal barrels.

       (b)  Sand  Preparation
       In past times,  naturally bonded molding sand was univer-
sally  used for green  sand  molding.  Preparation of the sand for
reuse  consisted  of adding  water  and some new sand to replace
the amount sticking to, or embedded in,  the  surface of the
castings.  This  sand  has been almost  completely replaced by
clean  silica sand  to  which is added water and the various
binders required to produce the  desired molding characteristics.

       Sand preparation in  the majority  of today's foundries is
accomplished on  the foundry floor by  adding  moisture, binders,
and new sand to  the used sand.   A number of  types of mobile and
portable equipment are used to cut, screen,  mix,  and aerate the
sand to prepare  it for reuse.

       Mechanized foundries  are generally equipped with fixed
sand preparation equipment  to which the  shakeout  and spill sand
is transported by  conveyors  and  elevators.   After preparation,
including magnetic separation of tramp  iron,  screening,  addition
of binders and moisture, mulling, and possibly  aeration,  the
prepared sand is conveyed  to the molders.  Exhibit IV-26
illustrates a typical sand mulling unit.

      High production foundries normally  reuse  the molding sand
a number of times each shift.  If the sand is not  effectively
cooled after each use, the temperature builds up  to  the point

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                                                       IV - 33
where evaporative cooling of the prepared  sand  occurs.  A
significant amount of moisture added in  the miller can  be  lost
before the sand can be formed into a mold  resulting  in  a change
in che characteristics of the sand.   This  condition  plus the
heat remaining gives rise to casting defects.   Conventional
cooling is accomplished in the muller by directing a flow  of
cool air through the mixer.   A new concept, absorption  cooling,
has recently been patented and is in use in several  foundries
with reported success.  This process is  described in Section
   LI
IX.
       (c)   Sand Reclamation
       Three basic types of sand reclamation units are available--
dry, wet,  and  thermal.  In the dry system the sand is first
screened  and crushed  to reduce the lumps and is Chen discharged
into a dry scrubber where the grains are subjected to the
blowing action of  low pressure, high velocity air.   The result-
ing  impaction  and  scrubbing  action between Individual grains
cleans the sand.   For wet reclamation the sand, after screening
and  crushing,  is  slurried with water end pumped into a. wet
scrubber  equipped with a  rapidly  revolving propeller.  The sand
is agitated violently, causing multiple collisions  of the grains.
The  slurry is  next  pumped into a  classifier where the fines are
 removed.   Finally,  after draining,  the  sand is dried and cooled.
The thermal reclaimer consists  of a  multiple hearth furnace
 into which the screened  and  crushed  sand  is fed.  The sand is
 heated to about  1300° F  and  plowed from shelf  to shelf within
 the gas fired chamber.  Cooling and screening  to remove the
                                     9,  13
 sand fines complete the  reclamation.
                                                                                                                                    IV -  34
Cleaning,  Heat Treating
  and Finishing
      Cleaning and finishing of castings are the final opera-
tions performed in the foundry.  Cleaning of castings generally
refers to  the operations involved in the removal of sand and
scale; sprues, gates, and risers; and fins, wires, chaplets or
other metal not & part of the casting.  The castings, after
they have  been separated from sand at the shakeout screen, are
cooled in boxes or on a conveyor which moves them to the cleaning
and finishing area.  For gray iron castings, the gating system
may be broken off by impact in the shakeout, or they may be re-
moved on the casting delivery conveyor.  Heads and gates on
ductile iron castings may require burning or sledging.

      These operations ace shown on Exhibit IV-13.
      (a)  Cooling and
      	Sorting
      Following shakeout and sprue removal, castings  are  cooled
before being sent to the cleaning and finishing area.   Cooling
can be accomplished in a variety of ways, depending on the  size
and shape of the castings, the rate at which castings  are pro-
duced, and the degree of mechanization in the  foundry.  Several
types of conveyors—pallet, flat chain, belt,  and  overhead
chain—are used in high production shops, while other  shops cool
in boxes or simply by piling the castings on the floor.   Sorting
is generally done after a sufficient amount of cooling and  in-
volves separating the different products into  handling containers.

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                                                       IV - 35
      (b)  Castings Cleaning
      The removal of sprues, gates  and  risers Is usually the
first operation in the cleaning  room.   This is done by impact,
shearing, abrasive cutoff,  band  or  friction sawing, or torch
cutting depending upon the  size  of  the  casting and the type of
iron.  Abrasive cutoff wheels can be used for removing gates
and risers on castings made of hard- or difficult-to-saw alloys.
Gates and risers on large ductile castings are most conveniently
removed by gas cutting.  Band or friction sawing may be used
where it is desirable to follow  the contour of the casting.
      Surface cleaning operations ordinarily follow removal of
the gating system for all foundry castings except malleable iron
castings which are heat treated  before  surface cleaning operations.
Abrasive operations such as shotblasting, sand blasting, and
tumbling are normally used.  Wire brushing, buffing, pickling,
and polishing operations may also be performed in some cases.

      Shotblasting the casting surface  is a rapid means of re-
moving sand and scale.  The abrasive  action removes the mold
sand, scale, and burrs.  There are  several methods  for propelling
the abrasives used in blast cleaning  and a great variety of
abrasive mediums may be used.  The  common abrasive mediums used
in foundry application are sand, grit and shot.  Grit consists  of
angular metallic particles and the  round metallic particles form
the  shot.
                                                        IV  - 36
      Two basic methods employed for blasting  are:
           1.  Mechanical blasting, in which the  abrasive is pro-
pelled by means of a power-driven,  rapidly  rolling  bladed wheel.
           2.  Air blasting, in which the abrasive  is  propelled
through a nozzle by compressed air.
     Of the  two methods, mechanical blasting is  the more widely
used in foundries.

      Various shot blast machines  are available  including rotary
tables, tumbling units, rotary drums, continuous  cabinet types,
portable hand-operated units, and  cleaning  rooms  for very large
castings.  An illustration  of a commonly used  cabinet type shot-
blast unit is shown in Exhibit 1V-27.

      (c)  Heat Treating
      Iron castings are heat treated to  improve  physical
characteristics and to improve machineability.  Typical heat
treating temperature ranges for gray iron are:
               Stress Relief        1000°-1250°  F
               Anneal               1250°-1725°  F
               Normalize            1725° F
               Quench and Temper    1550°-1600  F
Annealing of white iron castings to produce malleable iron is
done at 1600°-1750° F.  Batch-type or continuous  furnaces may
be used depending upon the type of heat  treating  and production
requirements.

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                                                     IV  -  37
      (<0  Casting Finishing
      Following surface cleaning and heat treating, castings
are finished to remove gate and riser pads,  chaplets, wires,
parting line flash not a part of its final dimensions.  Chipping
hammers and grinders are used for these operations.

      Castings that can be handled manually  are  trimmed or
ground on bench,  floorstand, or portable grinders.  Swing-frame
or portable grinders are used for trimming castings that are too
heavy to be carried or held by hand.

      Tumble finishing may be used in providing  final finish on
some castings. This process involves the tumbling or rolling of
parts in rotating barrels or the agitation of parts in shaker
containers.  Vibratory tubes or other comparable equipment  for
cleaning, shine rolling and burnishing are also  used.

      (e)  Casting Coating
      The large majority of iron castings are  ready  for ship-
ment after finishing operations are completed.   Some casting
specifications, however, require that a surface  coating be
applied for rust proofing or other reason.  Rust preventive
paints are usually applied by spraying, fogging, or dipping,
depending upon the type of coating, casting  size and shape, and
production requirements.

      The painting facility may include conveyors, spray booth,
dip tank, a conveyor system, and a drying oven.
                                                                                                                                      IV - 38
Coremaking
      Cores are normally made of silica sand and organic or
inorganic binders.  The selection of the core formulation and
process best suited to a particular application requires consid-
eration of many factors Including green strength, dry strength,
porosity, core complexity, quantity of cores required, and raw
material, equipment and production costs.

       (a)  Core Processes
      The major coremaking processes in current use  for  castings
are;
               -  Oil Sand Cores
               -  Shell Cores
               -  Silicate Bonded Cores
               -  Furan Cores
                  Hot Box Cores
               -  Alkyd - Isocyanate Cores
                  Phenol - Isocyanate Cores

      Oil sand cores are widely used although silicate and resin
bonded cores are being used in greater numbers each  year.
Vegetable or mineral oils are commonly used as binders.  Cereal
binders and clay are often used in conjunction with  core oils.
The cereal binders, mostly derived from corn, are added  to im-
prove green and dry bond, decrease the oil required, and improve
collapsibility of the core.  Clay is often added in  small amounts
to increase the green strength.

      Shell cores for iron casting are usually made  with phenol-
formaldehyde resin and round grain silica sand.  Large users of

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                                                     IV - 39
shell core sand find It economical  to buy bulk resin and coat
Che silica sand themselves.   Premixed sand and resin is avail-
able commercially for the smaller user  for whom this is not
economical.
      Hollow shell cores are made by the investment process,
and small, solid cores can be made  in a hot box machine.  No
oven is required for shell cores  since  they cure quickly in the
coremaking machine.
      Silicate bonded cores are made in a molding or core blow-
ing machine, end set by the application of carbon dioxide in a
manner that permits  the gas to completely permeate the core.
Since the storage life of silicate  bonded sand is short when
exposed to the air,  due to absorption of C02, the mixed sand
must be stored in covered containers.
      Furan air-set  cores employ  resins made from furfuryl
alcohol, ureas, and  formaldehydes.   The resins are mixed with
core sand and a phosphoric acid activator in conventional mix-
ing equipment.
      Hot box core resins include furfuryl alcohol, urea-
formaldehyde and phenol urea-formaldehyde.  The liquid resin
is mixed with the core sand and activated in conventional
mixing equipment. An exothermic  reaction between the resin
and the activator progresses quickly when the mixture enters
the heated core box  in a core blower.
      The alkyd-isocyanate process  involves the use of a synthetic
oil binder which, when mixed with sand  and activated chemically,
                                                                                                                                                    IV - 40
produces cores that cure at room temperature.  The key to the
process is the polymerization reaction  that  provides  advantages
in terms of time and thoroughness of set.
      Phenol-isocyanate Is a new no-bake process  that was in-
troduced in 1970 and Is based on a urethane  resin system.  One
type of process consists of a binder and catalyst used In equal
portions.  An advantage of this process is that strength and
hardness properties are obtained at binder levels'lower than
with other systems.
      (b)  Core Department
      	Process Flow
      Exhibit IV-15 illustrates  the  process flow Cor the making
of sand cores.  Sand is purchased  in bulk quantities and ship-
ments are stored In silos or  bins.   Small quantities of core
premixes, resins, binders and other  additives are received in
bags or drums and stored indoors.
      The sand storage bin  is often  located above the mixer to
permit discharge to a weigh hopper directly above the mixer
inlet.  Other dry and liquid  materials  are measured by weight
or volume and added to the  mixer at  the appropriate point in
the mixing cycle.  The core sand mix is discharged from the
mixer and transferred to the  core  machines by conveyor or tote-
box.
      The selection of the  proper  machine for forming the core
will be determined, in part,  by  the  type of sand mix employed,
such as shell or hot box mixes which require specially designed
equipment for core box investment  and heating.  Other processes

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                                                      IV - 41
permit the use of a variety of machines.   Simple  cores  required
in small quantities are made manually at  a core bench using  a
wooden or metal core box.   Cores  with a constant  cross  section
can be made in the desired length in a povered or hand-operated
extrusion machine.  Molding machines of all types including
rollover, jolt and squeezer machines, and sand slingers  are
Still in use in many foundries, but  the use of core blowing  and
shooting machines has become more widespread in recent  years
except for large cores.

      After forming, those cores  that achieve a primary or com-
plete set while in the core machine  require no special  handling
since they have sufficient structural strength to permit placing
on storage racks or in tote pans  for storage or further process-
ing.  Cores requiring an oven bake or gasing are  placed on a
flat core plate or a formed core  dryer providing  rigid  support.

      Oil sand cores requiring baking are transferred to gas or
oil-fired ovens.  Light oil fractions and moisture in the sand
are evaporated, followed by oxidation and polymerization of  the
core oil.

      Core finishing operations consist of cleaning, sizing,
and assembling.  The cleaning operations  include  trimming,
brushing, coating, mudding, and venting.   The trimming  and
brushing removes fins and  excess  sand.  Core coatings,  or
washes, improve the surface of the casting and insulate  the  cores
from the molten metal.
                                                                                                                                     IV - 42
      Holes or depressions in a core are  filled  and,  if addi-
tional vent holes in the core are  required,  they are  made at
this point.

      Sizing of cores includes gaging of  the core  and filing or
grinding to the required dimensions.

      Complex cores sometimes require that they  be made in
separate parts and assembled into  final form with  core  pastes.
Occasionally other methods of fastening cores together  are used
                13
such as bolting.

Pattern Making
      Foundry patterns are normally made  of wood or metal.
Patterns for small production runs tend to be the  former and for
large production runs, the latter.  Wood  patterns  generally
have a shorter useful life, although they can be repaired more
easily than the metal patterns which usually have  a higher first
cost.  A large production requirement, however,  often results
in a lower pattern cost per mold with metal molds.

      Typical  pattern making  steps include  cutting the wood or
metal pieces  to size, fastening  the  pieces  together,  and paint-
ing, varnishing and mounting where required.   Match plates are
often cast from the original patterns.

      Wood pattern shop equipment  includes  different  types of
saws, planers, joiners, lathes,  edgers,  routers  and drill
presses.   Metal pattern making equipment  includes typical machine
shop tools.

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                                                         IV - 43
                         REFERENCES

       1-  U.S. Department of Commerce  Neve. Business and Defense
Services Administration, BD 69-14, March 13, 1969.
       2.  A Systems Analysis Study of  the Integrated Iron and
Steel  Industry. Division of Process Control Engineering, National
Air Pollution Control Administration,  Department of Health,
Education and Welfare, Battelle Memorial Institute, May 15, 1969.
       3.  The Cupola and Its Operation, published by the American
Foundrymen's Society, 3rd ed., 1965.
       4.  Metals Handbook;  Volume 5 Forging and Casting, pub-
lished by the American Society for Metals,  8th ed., 1970.
       5.  "Continuous Iron Melting," R. S.  Amala and J. B.
Walker, Modern Casting. May, 1970, p. 45.
       6.  "Some New Factors Affecting Cupola Operation," H. W.
Lownle, Modem Casting. 1966.
       7.  Principles of Metal Casting. R. Heine, McGraw-Hill
Book Co., 1955, pp. 550-553.
       8.  "Comparing Processes foi Making Ductile Iron," Dr. E.
Modi, Foundry. July, 1970,  pp.  42-48.
       9.  Molding Methods and Material, published by the American
Foundrymen's Society, 1st ed.,  1962.
     10.  Casting Materials Company.
     11.  "Beat Hot Sand Problems with Absorption Cooling,"
A. J. Wagner,  Modern Casting.  August, 1970,  p.  46.
     12.  "Progress in Coremaking," W.  0. Ferguson,  Foundry.
August, 1970,  pp.  53-59.
                                                                                                                                          IV - 44
     13•  Foundry Core  Practice.  H.  Dietere, published by  the
American Foundrytnen's Society,  3rd ed. ,  1966.

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                    V -  EMISSIONS  PRODUCED AND
                    EMISSION CONTROL CAPABILITY
EMISSIONS PRODUCED IN
  THE BASIC PROCESSES
     Emissions consisting of particulace matter,  fume, smoke,
or gas are a by-product of every  foundry process  and almost
every foundry operation.   It is necessary  that the source of
these emissions and the factors affecting  their type and quantity
be identified so that the foundry emissions problem can be
evaluated.

     The type, concentration, and size  of  typical foundry emissions
are tabulated in Exhibit III-7 by department  and  operation.  These
emissions are identified in the following  paragraphs and evalu-
ated in a later section of the report.
Raw Material Storage
  and Charge Makeup
     The handling, preparation, and charge makeup of the basic
foundry  raw materials — scrap metal, coke,  and limes tone--may
produce  emissions in a variety of ways.  The  storage of  coke  and
limestone over extended periods  may result in the disintegration
of these materials from the action of the sun,  rain, and repeated
freezing and  thawing.  Ferrous scrap rusts rapidly.  Subsequent
handling during the makeup of furnace charges may cause  lime-
stone dust, coke breeze and small quantities  of rust to  be  re-
leased into the environment.  At  conveyor transfers, as  well  as
storage  bins, weigh hoppers and  the location  where  these
                                                                                                                                    V -  2
materials are placed in charge buckets, emissions  tend  to
increase due to tumbling of the material.  Rehandling of coke
results in additional disintegration and, to a  lesser degree,
this Is also true of limestone.
     The preparation of metallic charge materials  including
the breaking and cutting of large scrap, removing  cutting  oil
residue from machine shop turnings and borings  in  preparation
for briquetting, and cleaning of foundry returns represent an
additional potential source of emissions.  The  industry trend,
at least for the larger foundries, is Co purchase  scrap to
definite specifications to eliminate Che need for  scrap pre-
paration by the foundry, except for foundry returns.  A few
foundries make briquettes from internally generated  turnings
and borings, but most companies in this position sell  the
turnings and borings and purchase briquettes according  to  their
needs.  For the foundry that does convert its machine  shop
scrap into briquettes, the removal of oil on the turnings
represents a source of potential emissions if the  scrap is in-
cinerated, and to a much lesser degree if the scrap  is  centrifuged.
Shot blasting of foundry returns may produce emissions  in  the
form of dust from the embedded sand and from broken  shot.   Shot
blast machines are normally furnished with dry  mechanical  col-
lectors or fabric filters.

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                                                     V - 3
                                                                                                                                  V - 4
Melting
     The melting department  is responsible for the greatest
amount and heaviest concentration of emissions in the foundry,
producing the need for control equipment on cupolas, electric
arc furnaces, preheaters  and dryers.  Emissions from coreless
induction furnaces are insignificant due to the quality of
scrap and the fact that no combustion takes place in the units.
Channel induction furnaces also produce minimum amounts of
emissions and are seldom  provided with emission control equip-
ment •
     The cupola is the largest single source of emissions,
producing fume, smoke, particulate matter and gas.  Concentra-
tions are affected by the quality and quantity of charge materials,
Che use of techniques such as oxygen enrichment and fuel injection,
the volume and rate of combustion air, and the melting zone tem-
         3
perature.
     The electric arc furnace produces somewhat less emissions
than the cupola because no fuel or combustion air is required.
Combustion in an arc furnace is limited and results from the in-
clusion of combustible elements in the charge and from burning of
the electrodes.  Concentrations may be great enough, when used as
a prime melter, to require emission control equipment.   Emissions
Include smoke, fume, dust, and possibly some oil vapors in con-
centrantions that are affected by the quality and composition
of charge materials and the temperature of the bath.   Emis-
sions are greatest during the melt-down phase of  the  cycle,
and less after melting is completed, when the molten  metal  is
covered with slag.
     Induction melting produces light concentrations  of  emis-
sions consisting of fume, smoke, and oil vapor.   Control
devices are usually not provided or required.  The  smoke and
oil vapor usually derives from small amounts of cutting  oil
adhering to the steel or iron scrap, and can be eliminated by
preheating prior to charging into the induction furnace.
     The reverberatory or air furnace for melting or  duplexing
produces light to moderate concentrations of emissions.   Com-
bustion occurs within the furnace but the gas or  oil  fuel is
burned in highly efficient burners above the metal  bath.
Smoke and fume are produced in this type of furnace.   The
smoke results from combustion of oil on the scrap and other
combustible materials in the charge.  Metallic oxides appear
in the emissions as in any melting furnace, and are the  result
of nonferrous contaminants in the charge material,  vaporized in
the molten bath with a portion of the iron scrap.   The concen-
trations are related to the partial pressures of  the  oxides  at
the melting temperature.
     Preheaters or dryers for furnace charges are another
source of emissions in the melting department.  They  are
rarely used in conjunction with cupolas or reverberatory

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                                                     V  - 5
furnaces since these are highly efficient preheaters  in  them-
selves.  The use of a preheater as a means of increasing
melting capacities of electric arc and induction  furnaces,
and to insure dry furnace charges essential to the  induction
furnace, transfers the majority of the emissions  production
from the furnace to itself by burning combustibles  which
would otherwise burn in the furnace.  The resulting emissions
are therefore the same type and appear in the same  quantity
as would be found In these furnaces without preheating.4

     Coreless induction furnaces used as holding  or super-
heating furnaces charged with molten iron emit minor  amounts
of metallic oxide fume and are rarely provided with emission
control equipment.

Magnesium Treatment for
  Producing Ductile Iron
     Treatment of molten iron with magnesium compounds to
produce ductile iron is a significant source of foundry  emis-
sions.  Emissions from this operation consist primarily  of
magnesium oxide representing up to 65% of the metal injected.
The high loss occurs since the boiling point of magnesium is
far below the temperature of the molten iron.  The  reaction
is often violent, depending on the form of magnesium  used,
and shielding or enclosing of the ladle at this time  is  re-
commended for this reason as well as to insure maximum col-
lection with a minimum dilution with Infiltrated  air.
                                                                                                                                     V -  6
     Molten metal  in a  furnace or ladle produces a shimmering
 heat wave  above  its  surface which is often mistaken for emis-
 sions  rising  from  the bath.   The phenomenon is an optical
 illusion resulting from the varying index of refraction of
 the unequally heated air strata,  and is present where molten
 metal  is used.

 Molding, Pouring
  and  Shakeout
     The molding operation  is not a major contributor to
 foundry emissions.   In  green sand molding,  moisture in the
 sand acts  as  a dust  suppressant.   Small quantities of dry
 parting compound are emitted when the mold halves are dusted
 with this material.   Liquid  partings used to prevent molding
 sand from  sticking to metal  patterns or match plates have a
 kerosene base.   When sprayed on the patterns,  a portion of
 the vehicle vaporizes,  and  the  solids such as  stearic acid
 are sprayed into Che air  in  the immediate environment.   Sea
 coal is also  used  as a  mold  spray and is released into the
 atmosphere.   Concentrations  are very light.

     Emissions from  the pouring operation are  much more severe
 than from molding  and are usually more  difficult  to capture.
 The hot metal, when  poured into the  mold,  first  ignites  and,  as
 oxygen in the mold is exhausted,  thermally  degradates such
materials in  the sand as sea coal, cereal and  synthetic  binders,
 and core binders.  Steam is  formed in green sand molds  from the
moist sand.

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                                                     V  -  7
     In che full mold process,  the complete pattern is consumed.
Concentrations are usually relatively low  for a single mold, but
the multiplicity of molds produced increases the severity of the
problem.  Most of the emissions are steam, vapor, and smoke.
In the full mold process and for many of the synthetic binders,
emissions may be toxic,  and only the low concentration per mold,
coupled with general foundry ventilating systems, prevents phys-
iological reactions in molders, pouring crews and shakeout men.
Examples of potentially  toxic emissions are styrene, low mole-
cular weight polystyrene, ethylbenzene, methyl chloride, chlorine,
hydrogen chloride and decomposition of evaporative products in
addition to CO, CO. and  HjO.

     The pouring of ductile iron results in further emissions
of magnesium oxide from  the magnesium treatment process.  The
concentration of smoke,  fume, gas, and vapor is related to the
hot metal temperature, length of time between pouring and shake-
out, and the quantities  of binders,  moisture and parting com-
pounds in the molding sand.

     At the shakeout, the action of separating castings from
molds brings hot castings into  contact with moist molding sand
not adjacent to the sand-metal  interface at the time of pour-
ing.  This results in additional smoke, steam and vapor of
the same type emitted during the pouring operation.  Concen-
tration of emissions is  momentarily high, but the casting is
cooler than the molten metal while pouring, the sand is quickly
separated from the casting, and the emissions are often able
to be contained and removed through the use of ventilated hoods.
                                                                                                                                    V - 8
Sand Conditioning
     New molding and core sand are ordered to a  desired screen
test for specific use and always include some fines.   The es-
cape of fines into the atmosphere varies with the method of
handling.  Closed systems such as pneumatic conveyors  release
only small amounts and are provided with exhaust connections
at the inlet and the receiver.  Systems using belt  conveyors
and bucket elevators for dry sand may release fines and dust at
transfer points between conveying units.  Many smaller foundries
unload and transfer sand to floor level bins manually,  or with
front-end loaders.  Load and unload points are generally un-
controlled.  The handling of conditioned molding or core sand
presents fewer problems than new sand because of the moisture
content and binder additives and therefore control equipment
and hoods are generally not required.  Shakeout  or return sand
produces more emissions because it has been partially  dried
from contact with the hot metal.  Introduction of fresh spill
sand from the molding floor and excess prepared  sand helps
considerably in cooling, moistening and decreasing dust and
fines from being released to the atmosphere.  It is considered
good practice to enclose the transfer points of  conveyor systems
handling dry sand, and to provide exhaust connections  at these
locations and at the vibrating or rotating screen and  the return
sand storage bin.
     Moderate concentrations of fines, dust and  binder materials
are emitted at the sand mixer.  Concentrations are increased if

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                                                      V  -  9
the muller is equipped for sand cooling.  This  is  accomplished
by directing a blast of cooling air either  over or through  the
sand while it Is being mixed.   The air blast  entrains  small
particles and must be exhausted to a control  device to separate
Che dust from the air blast

Cleaning and
  Finishing
     Cleaning and finishing operations produce  emissions  less
troublesome than other foundry processes.   Particulate matter
is generally larger and easier to capture and separate from
the air stream even though concentrations can occasionally  be
moderate to heavy.  The metallic dust and particles removed
from grinding operations have a high density  permitting the
use of less expensive dry mechanical collectors but require
higher entralnment velocities for removal from  the working
surface.  Particulate concentration is dependent upon  type
and surface speed of the grinding wheel and the amount of
pressure exerted by the grinder.  Chipping  operations  produce
such large particles that control equipment is  not required
except when chipping castings with burnt-in sand.   In  this
event, good foundry practice dictates the wearing  of a face
mask.  Abrasive shotblastine produces high  concentrations of
metal particles, sand dust, and broken shot but modern blast
machines are provided with high efficiency  fabric  filters
designed for the purpose.  The concentration of these  emis-
sions is a function of the quantity of embedded sand on the
castings, fracture strength of the shot, and length of time
                                                                                                                                    V - 10
in the blast cabinet or room.  Sand blasting, now seldom used,
produces high concentrations of sand dust with concentrations
related to air pressure, blast sand characteristics and length
of time required for cleaning.  Sand blast operators wear ven-
tilated hoods to prevent inhalation of sand dust.
     Emissions from annealing and heat treating furnaces are
minimal except when the castings have previously been oil
quenched.  Concentration of the resulting smoke is a function
of the amount of oil residue on the casting surfaces.  Paint-
ing is infrequently done by foundry departments.  Emissions
from this operation consist primarily of vapors from thinners
and concentrations depend on the type and quantity of the
volatiles.

Coremaking
     Emissions problems in the core department are similar  to
those encountered in the handling of molding  sand.  No major
difference exists for the handling and storing of new sand.
The coremaking operation using synthetic binders and heated
core boxes often results in vapor and gases;  some of them
may be toxic or acrid in nature.  A similar situation exists  in
some of the synthetic binders that set at room temprratures,  and
to a lesser degree with oil sand coremaking.  Oil sand cores
require oven baking to dry and polymerize the oil binders.
Core oven emissions can be highly odorous.  Incineration is the
most satisfactory way to control these emissions, using after-
burners or catalytic combustion chambers.  Concentrations of

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                                                     V - 11
                                                                                                                                  V - 12
Che emissions vary with Che Cype  of  binder used.   Wlch che
wide variety of binders now available  and others in Che develop-
ment stage, conservacive and flexible  design criteria for col-
lection ductwork and concrol systems would be recommended.

Patcern Malting
     Wood pattern shop emissions  consist primarily of wood
dust and chips.  Concentration can be  high for  each machine
tool but normal utilization factors  of the machines reduce
the system capacity.  The wood dust, having a low density
and-laree surface area, is easily entrained.

EMISSION CONTROL
  CAPABILITY
     The current state of the art of foundry emissions  control
does not fully satisfy the needs of  the industry.  Although,
on a purely technical basis, virtually all particulate  and
most gas, smoke and fume emissions can be controlled, the cost
of such control for several basic foundry  processes  is  often
beyond the  financial ability of the small-  and medium-sized
foundries, which comprise the large  majority of the industry,
to support.  The current foundry need is for  the development
of equipment to control emissions from cupolas, electric arc
furnaces, ductile  iron production by magnesium treatment,
mold pouring stations, and coremaking operations at costs  that
do not threaten the profitability, and even the existence,  of
 the small  foundry.
Emissions Controllable
  with Existing Equipment
  Design	
     Relative controllability of foundry emissions  is  indicated
in Exhibit III-7 on a comparative basis.  Emissions more  dif-
ficult to collect are by and large Chose with  large concentrations
of very fine particles, five microns and smaller.   Conversely,
emissions easier to collect are those consisting  entirely of
large particles.

Particulate Emissions
  Uneconomical to
  Control	
     Generally, all foundry emissions are uneconomical to
control, since the collected material has little  or no value,
and its collection adds no value to the foundry's product.
The installation and operating costs of control systems vary
over a wide range, and it is necessary to identify  those
operations requiring highly uneconomical systems  beyond the
financial capability of the majority of foundries.

     The cost of an emissions control system depends on the
following variables:
             Properties of emissions, including size distri-
bution, density, chemical composition, corrosiveness,  solu-
bility, combustibility, and concentration.
             Difficulty of capturing the emissions  in  an  air,
gas, or water stream of moderate temperature and  volume.
             Difficulty of separating emission particles  from
the captor medium.

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                                                     V  -  13
     Properties of Che raaCCer to be collected are generally
fixed by the process and raw materials,  although modification
of the equipment could possibly alter the  properties.  Assum-
ing them to be fixed for a given operation,  the first  consid-
eration Is Che cost of capture.  If the operation occurs  In  an
enclosed and fixed location such as a melting  furnace  or  oven,
capture may be relatively simple and may be  accomplished  at
low cost although emission collection and  separation costs
could be high.  If the location of the operation  Is not fixed
and occurs  in  Che open, such as pouring of molds  set out  on
the foundry floor, then capture Is difficult and more  expensive.
In the  latter  case, with pouring emissions dispersed through-
out the plant, much of the air  in  the building must be pro-
ceased  trough the control system  to collect the emissions.
A system  of this  capacity would be expensive to Install and
operate.
     The  third factor  of  system cost is the difficulty of
 particle  separation from the captor  medium.  Large, dense
 particles,  such as  metallic  fragments  from grinding operations,
 can usually be separated by  the use of relatively  low cost  dry
 centrifugal collectors.   Submicron-slzed  metallic  oxide particles
 from a melting furnace,  however,  require  more costly  collection
 equipment such as high energy wet scrubbers or fabric filters.
      An analysis of foundry operations identifies  processes
 combining difficulty of emission capture  and  collection  with
                                                                                                                                    V - 14
high cost of the control equipment.  These are briefly  dis-
cussed below while an evaluation of these emissions are pre-
sented In Section VI and relative costs are  tabulated In
Exhibit III-7.

     (a)  Cupola
     Iron melting in a cupola produces heavy concentrations
of particulate emissions in a gas stream up  to 2000° F.   In
most cupolas, large amounts of air are infiltrated through
the open charging door greatly increasing the cost of the
control system, since the size and cost of a collector  is
directly related to the volume of gas to be  handled.
     (b)  Electric Arc
      	Furnace
     The electric arc furnace when melting iron  produces
moderately heavy concentrations of particulaces  with a  large
percentage of the total particles below five microns in size.
The gas stream is well over 2000° F, requiring cooling  by
infiltrating air or by water sprays.

     (c)  Magnesium Treatment
          for Producing Ductile
          Iron	
     This process results in heavy concentrations of extremely
fine metallic oxides, principally magnesium oxide.
     (d)  Mold Pouring
     Mold pouring produces only moderate concentrations  of
emissions, but in many foundries capture is very difficult.
In addition,  the emission may be toxic or acrid.

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                                                      V -  15
     (e)  Coremaktne
     Coremaking and baking or heating for  setting  of the
binders result In moderate concentrations  of  sometimes  toxic
and acrid emissions.  Smoke and vapors from floor  or core-
making operations are difficult to capture with  only moderate
dilution and are therefore expensive to control.   Core  baking
oven emissions can be controlled with afterburners or cata-
lytic combustion chambers.
     These five processes represent the sources  of foundry
emissions not readily controllable, or highly uneconomical to
control.
                                                                                                                                    V  -  16
                         REFERENCES

     1.  Conference on Foundry Ventilation  and Dust Control,
Harrogate, England, 1965.  British Cast  Iron  Research
Association, Alvechurch, Birmingham.
     2.  Foundry Core Practice. H. W.  Dletert,  American
Foundrymen's Society, Des Plaines, Illinois,  3rd ed., 1966.
     3.  The Cupola and  Its Operation.   American Foundrymen's
Society, Des Plaines, Illinois, 3rd  ed.,  1965.
     4.  Air Pollution Engineering Manual.  U. S. Department
of Health, Education and Welfare, Publication 999-AP-40, 1967.

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                   VI  -  QUANTIFICATION AND
                   EVALUATION  OF  EMISSIONS
DESCRIPTION OF SAMPLING AND
  ANALYTICAL TECHNIQUES
     Measurement or sampling of emissions  from a  foundry
source can be conducted in the general  atmosphere near  Che
suspected source or in a specific stack.   The sampling  alter-
native used depends on the objectives of  the measurement which
Include:
          1.  Determining whether stack emissions are  in vio-
lation of existing ordinances.
          2.  Providing a guide in selection  of  proper  control
equipment.
          3.  Evaluating the effectiveness of control  equip-
ment after installation.
     Various  techniques and methods are available for  sampling
emissions in  the atmosphere or stack,  and Che adequacy and
effectiveness of these methods vary widely depending on which
one  is  employed. *•
General Atmosphere
   Sampling
     Many  different area or atmosphere sampling methods are
used in various sections of the  country.  Normally, the con-
centration of dust collected  by  area sampling methods  Is re-
ported  in  micrograms  per cubic meter and coarse  dust fallout
                 A T KF-KRVFY ft rOMPAVY Ivr
                                                                                                                                    VI - 2
in tons per square mile per month, pounds per 1,000 square
feet per 30 days, or as a soiling Index.  Such samplings are
conducted off the premises of a particular plant and a local
agency procedure is followed rather than one related to a
specific Industry.
     Various factors such as frequency of sampling, wind,
humidity, topography and analytical procedures are  important,
no matter which method is used to sample contaminants  in  the
general atmosphere.
     Usually, particle fall  is best determined by  frequent
short  time cumulative samplings  rather  than  one  continuous
cumulative sampling over a  long  period  of  time.   The  summa-
tion of a series  of samples  can  produce data approximately  as
accurate as, and more  economically  than, a continuous sample.
     Meteorology factors  such  as wind and  humidity, and also
topography  observations  including the relation of differences
in surface  elevation  of  the surrounding area, hills,  valleys,
terrain and buildings, must be recorded when atmosphere sam-
pling of emissions is  made.
      How the sample data will  be analyzed, and the type of
 equipment used, must be  determined prior to sampling so that
 the proper sampling procedure  is pursued.   The adequacy of any
 quantitative general atmosphere sampling method is limited

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                                                      VI  -  3
                                                       VI -
because of the effects which diffusion,  turbulence, wind  veloc-
ity, wind direction and various other factors have on measure-
ment results.
     In addition to the quantitative  methods discussed, dis-
charge quality can be estimated by observing the opacity  or
discharge appearance from a stack. Opacity scales of light
obscuring degree, an adaptation of the Ringelmann Scale,  are
often referred to in air pollution codes.
     The Ringelmann Scale shown in Exhibit VI-1 is a chart for
grading the black density of s-nc'.cc- from  exhaust stacks and has
been used in the United States since  the early 1900's.  The scale
was originally designed for the purpose  of indicating the degree
of combustion control in coal burning equipment.  It was  not
designed to cover metal melting emissions.
     With Che Ringelmann Scale, an observer compares smoke
emission to the chart and estimates black density of the
smoke.  This method relies entirely on the personal evaluation
of an observer when viewing stack discharge.  Because smoke
emission colors other Chan black also occur, variations of
the Ringelmann Scale have been developed which refer to an
equivalent opaciCy rule.  This rule scates that if an emis-
sion, regardless of color, obscures an observer's view to
such an extent Chat smoke of a given  Ringelmann number would,
the emission is equivalent to a smoke plume of that number.
     Metallurgical processes such as iron melting  often emit
particulate matter down to one micron or less  in diameter.
These small particles often exhibit light scattering effects,
and cause the appearance of a high level of opacity  when emitted
from an exhaust stack in a gaseous stream.  When the Ringel-
mann Scale is used to determine concentration  or weight of  parti-
culates in metallurgical process exhausts, the presence of  these
submicron particles tends to lead to erroneous conclusions.

     Some air pollution control regulations specifically limit
the discharge of visible emissions in addition to  limiting  par-
ticulate concentrations of those emissions.  For these  regulations
Che legal criterion is the Ringelmann equivalent opacity test,
even though the application of a visual test for compliance  is
subjective and its reproducibility subject to  atmospheric con-
ditions.  Some other state air pollution boards have adopted
statements such as the following regarding the use of a Ringel-
mann Scale:  "The Ringelmann chare shall be used for grading the
light obscuring power of smoke.  It shall not  be used for
determining metallurgical fume emissions or measuring the opac-
ity of non-combustion process emission."  However, it is a
simple and rapidly applied test that will probably continue  to be
used for judging compliance to visible emissions standards  until
such time as test devices are developed that provide reliable,
inexpensive and reproducible results.

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                                                      VI  -  5
Stack Sampling
     The collection of representative samples  of gaseous  and
partlculate matter flowing through a stack requires  specialized
equipment, skills and knowledge and therefore  is a more compli-
cated procedure than general atmosphere sampling.  More than
one sampling method is usually used when sampling mixtures  of
particulate matter and gaseous compounds,  especially if sepa-
ration of the sample is required.
     Of the number of methods presently in use for stack  sam-
pling, those developed by the American Society of Mechanical
Engineers are the most widely employed.  The ASME has published
two Power Test Codes--(1) PTC 21-1941 "Dust Separating Apparatus"
and (2) PTC 27-1957 "Determining Dust Concentration  in a  Gas
Stream"—which are followed when the effectiveness of an  emis-
sion control equipment system is evaluated and/or  to determine
if an ordinance has been violated.  An adaptation  of the  ASME
Codes with special emphasis on the specific problems of  testing
foundry cupolas has recently been adopted by the American
Foundrymen's Society and the Gray and Ductile  Iron Founders'
Society,  Inc.  The recommended practice is discussed later
in this section, and a copy is included in Appendix  E.  The
data presented in  this report are from cupola tests  made
according to  the provisions included  in the ASME Codes and
were run  before  the adoption of the recommended practice.
     The  ASME lists four basic steps  to follow in evaluating
 the  effectiveness  of  an  emission  control  equipment system:
           1.   Secure  a representative emission sample.
                                                      VI  -  6

          2.  Filter and measure the dust contained  in the
sampled gases.
          3.  Measure the sampled gas volume.
          4.  Measure dust conditions such as  temperature,
pressure, composition and various other  factors.
     In  following this four-step procedure,  agreement must  be
reached  by  the parties to the  test  on certain  pertinent  items.
A  listing of  these  items appears in Exhibit  VI-2.
     The ASME provides a number of  tables to report and
analyze  test  results, major  headings of which appear below.
              General Information.
           -  Description,  Dimensions,  etc.
           -  Test Data  and Results.
           -  Pitot Tube and Dust Samples Data.
           -  Dust Caught by Separator.
           -  Size Analysis of Dust Samples.
           -  Efficiencies.
           -  Fuel and Gas Analyses.
           -  General Data
There are 69  lines  of data called for in the above nine
tables.  The  code manual, PTC  21-1941,  can be  referred  to
for a complete description of  all test  procedures  including
                              1  2
tables for  reporting results.'
     The ASME procedures described  in PTC 21-1941  and
PTC 27-1957 were followed by the foundries visited where
emission test results were obtained.

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                                                     VI - 7
     The ASME test procedures on dust  concentration and dust
separating equipment are adequate and  will produce accurate
results If followed by a trained team  of specialists.
     Of particular importance in any stack sampling method
is determination of emission particle  size since these data
will largely determine overall collection efficiency of a
control equipment system.  Considerable care must be exercised
in collection of samples so that agglomeration and shattering
of particles will not occur.  Particles 44 microns and larger
in size are normally separated by standard screens.  Particles
passing through the 325-mesh screen (44 microns or smaller)
can be estimated or quantified by one  of several methods.
          1.  Microscope Counting - A  small portion of the
dust sampled is suspended in a suitable liquid medium and
placed in a dust counting cell where the particles in each
size range are counted.  The ranges vary but separations of
up to 5, 6-10, 11-20 and 21-44 microns are usually made.
          2.  Settling Method -  A sample of the collected dust
is suspended in alcohol in a beaker.   Separation is then made
by filling the beaker to a mark 8 or 10 centimeters from the
bottom, stirring until completely mixed, letting stand for a
specified time and quickly siphoning off the liquid down approxi-
mately 6 centimeters below the starting level.  The settling
time is computed to give the size range desired and the opera-
tion is repeated approximately three times.  The particle size
range is then checked by microscope in a dust counting cell and
the dust particles are separated either by filtration or by
centrifuging for drying and weighing.
                                                                                                                                          VI - 8
           3.   Centrifuge  Separation -  This technique essen-
tially consists of  separating one-gram samples of dust into
sizes.  The specialized test  equipment required is manufactured
in Sweden.
          4.   Air Elutriation -  This method consists of separat-
ing microscopic particles  into size ranges by air elutriation.1
NECESSITY FOR
  STACK SAMPLING
  PROGRAM	
Test Reports Gathered
  and Analyzed
     Emissions data from 45 stack sampling tests  tabulated in
the foundry data bank were available for  the  evaluation of
cupola emissions as functions  of furnace  design and operating
variables.  The data were obtained  from foundry operators
during plant visits, testing  laboratories, equipment manufac-
turers, state  pollution control boards, and published litera-
ture.  Stack sampling tests were not conducted specifically
for this study.  The collected data were  not  adequate to
completely define and quantify the  effect of  all  melting
variables on emissions levels.  The analyses  did,  however,
identify certain design variables that have no significant
effect on emission levels and  a number of variables having
either a quantifiable effect or a definite, if not completely
defined, effect on emissions levels.

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                                                      VI - 9
Need for Additional
  Data	
     Additional testing of cupolas would be required  to  defi-
nitely establish mathematical relationships between all  opera-
ting variables and emissions rates.  The program  to achieve
this purpose would require the use of experimental cupolas of
several different sizes operating under laboratory conditions.
It has been determined that the results of such a program,
while of considerable future interest, are not essential for
the formulation of the recommended research and development
projects developed in this study, and for the completion of
this report.
EVALUATION OF
  CUPOLA EMISSIONS
Nature of Data
  Gathered
     The evaluation of cupola emissions and the development
of emission levels as a function of cupola design factors and
operating practices required analysis of three types  of Input
data: the design criteria for each cupola considered, the
actual operation at the time the stack tescs were made, and
the emission data at the cupola outlet, or control system
inlet.
     Detailed information on a total of 481 Iron melting
systems in 1968 foundries is tabulated in the foundry data
bank.  Cupola furnace installations represent 329 of  this
total.  The cupolas are classified according to type  of lining,
blast air, charging, gas take-off, and use of afterburners,
                                                      VI  -  10

oxygen enrichment, and fuel injection.  In addition,  the  data
bank lists cupola dimensions, capacities, blast air volumes
and temperatures, afterburner sizes and locations, and  other
appropriate data required to specifically describe the  instal-
lation.  Operating practices, including charge makeup,  type
and condition of scrap, and coke, are also shown.
     Partlculate emission levels, while commonly  reported in
various ways, are tabulated in the data bank  in  terms of
grains per standard cubic foot of gas, and for the analysis,
are converted to pounds per ton  of metal melted.  This  form
removes the effect of varying amounts of  infiltrated  air  on
concentrations  of partlculates.   Emissions listed in  the  data
bank show control equipment  inlet and outlet  concentrations
as follows:
          Test  Location                       Number  Reported
           Inlet concentrations  only                31
          Outlet  concentrations  only               70
           Inlet and Outlet concentrations         22
     The amount of emission  data available  from the foundries
 included  in  the data bank is limited even though the foundries
 were selected on  the basis of either having  control systems
 already installed or  in  the  late planning stage.
     A number of factors  result in the limited amount of data
 available.
           1.   Foundries  are  often reluctant to disclose  the
 results of stack testing, even on a non-identification basis,
 when the results Indicate that the control equipment is  either
 not meeting the applicable code, or is just barely meeting  it.

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                                                      VI  -  11
                                                                                                                                 VI - 12
          2.  Because of the high cost,  few  foundries  care  Co  pay
for stack testing co determine particulate concentrations from
uncontrolled cupolas already known to violate  the  code,  preferring
instead to invest those funds in the control equipment.
          3.  Equipment manufacturers do noc,  as a rule, re-
quire cupola emission levels when quoting control  systems.
Equipment designs are generally based on years  of  experience
and rules of thumb,  with design contingencies  usually  large
enough to cover variations in type and quantity of emissions
from one installation to the next.   Testing  of only the  final
emission is performed following equipment installation to
prove that contract guarantees have been met.
          4.  Stack sampling tests are expensive,  and  few
tests are made without a compelling need.
          5.  Stack testing required by  the  various emissions
control boards to prove compliance with  local  or state codes
are at the expense of the foundry.   Since the  control  board
is concerned only with emissions from the control  system,
this is by and large the only location in the  entire melting
and control system that is tested.
     For certain systems, such as fabric filters and high
energy wet scrubbers known to be operating properly in the
9W. efficiency range, the inlet concentration can be  esti-
mated very closely from the collector outlet emission  level,
or the amount of material collected.  This is  not  feasible
with dry centrifugal, low and medium wet scrubbers, or wet
caps where the total efficiency can vary as  much as 20%
 depending on the type and particle size distribution  of the
 particulate matter.

 Classification of Melting
   Processes by Type and
   Design Parameter	
      The features of melting furnaces are organized in  an
 orderly format to provide a basis for evaluating the  foundry
 data gathered from various sources.  The furnaces are classi-
 fied initially by type—cupola, electric arc, electric  induc-
 tion,  and reverberatory or air furnace.  The first three  types
 of melters are further divided by design parameters to  produce
 the  "family tree" patterns indicated in Exhibits VI-3,  VI-4,
 and  VI-5.   Each path from the top to the bottom of the  exhibits
 represents a theoretical classification.  An eleven-digit code
 describing each possible classification is used in order to
 facilitate identification of the system, and for ease in re-
 trieval  of information from a computerized data bank.   A
 description of  the  code  is  included in Appendix B.

     Most  theoretical  combinations  of furnace design parameters
 are  either impractical or mutually  exclusive, and do not exist
 in practice.  Exhibit  VI-6  shows  the  32  cupola classifications
 identified as practical  designs  in  current use.   The tally
marks indicate  the  distribution of  existing  cupola  designs
among these  32  classes,  for  the furnaces  in  the  data bank for
which emissions data were obtained.   The  tally marks are not
necessarily additive.

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                                                     VI -  13
Variables Affecting
  Emissions	
     Exhibit VI-7 portrays the major components  of particulate
emissions from iron melting cupolas and the percentage by
weight of the various materials determined by chemical analysis
of emissions from seven cupolas.  The nine components  can be
grouped into three major categories:  (1)  metallic oxides,
(2) silicon and calcium oxides, and (3) combustible materials.

     It has been reported that the amount  of metallic  oxides
occuring in cupola emissions is related to Che presence of the
respective metals in the scrap charge and  their partial vapor
pressures at the temperature of the cupola melting zone.    All
metallic oxides except those of iron indicate the presence of
nonferrous contaminants or alloying additions in the metallic
scrap.  For example, zinc oxide could result from the  presence
of galvanized scrap or from die castings,  lead oxide from
terne plate, aluminum oxide from aluminum  scrap, and chromium,
copper and cadmium oxides from plated materials.  Iron oxides
are always to be found in cupola emissions, the concentration
dependent on such factors as scrap thickness, degree of sur-
face corrosion, and temperature in the melting zone.
     The oxides of silicon and calcium, representing the second
category, result from lining erosion, embedded molding or core
sand on foundry returns, dirt from the scrapyard adhering to
scrap, or from the limestone flux.
                                                                                                                                VI -
     The third category of emissions,  combustible material,
includes coke particles, vaporized or patially burned oil and
grease,  particles from fabric coatings from automotive scrap,
and other similar contaminants swept up the stack by the top
gases.
     The range of concentrations of the emission components
reported by the seven foundries listed in Exhibit VI-7 is  in
                                                           4
general agreement with other reported data as shown below.
                Chemical Composition of Cupola Dust
Component
S102
CaO

MgO
FeO(Fe203,Fe)
MnO
Mean Range
20%-40%
3- 6
2- 4
1- 3
12-16
1- 2
Scatter Values
2 -18
0.5 -25
0.5 - 5
5 -26
0.5 - 9
     In addition  to  the presence  of  these materials in the
 furnace charge and the temperature of  the oxidizing atmosphere
 in  the melting zone,  other  variables would  be expected to in-
 fluence the  amount of cupola  emissions.   Specific blast rate,
 when increased, would be  expected to result in greater emis-
 sions by  entrairanent of metallic  oxides  and mechanical dusts,
 such as coke and  limestone.  A portion of the entrained par-
 ticles  is filtered out  of the gas stream by the burden, with
 a higher  burden offering  greater  opportunity of particle
 capture.   It is well recognized that emission rates are greater
 during  burn-down, due in  part to  increased temperatures re-
 sulting in larger gas volumes, higher gas velocity, lower

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                                                     VI - 15
collecting ability of the smaller burden height, and possibly
greater formation of metallic oxide  vapors in the melting
zone.  Furthermore, the height of the  reducing zone is shorter,
with less potential for reduction of the already formed oxides.

     It would be further expected that cupola emiss'ions would
vary directly as the percent of coke in the charge, and some
researchers have reported such a trend.   This is a reasonable
theory since degradation of the coke while weighing, charging,
and moving downward in the cupola shaft will result in an in-
crease of coke dust in the furnace.  Therefore, any change in
operating practice resulting in a decrease in the coke charge,
including heating of the blast air,  or injection of an auxil-
iary fuel, should have a beneficial  effect on the amount of
particulates emitted.
     The use of an afterburner, properly designed and installed,
will decrease the quantity of combustible particles released to
the atmosphere or control system.  Sufficient oxygen must be
provided through the charging door to  permit complete combus-
tion, and the upper cupola stack must  extend far enough to per-
mit time for comubstion before the particles are exhausted to
the atmosphere or to the emissions control equipment.  Defi-
ciency in either factor will tend to negate the potential ad-
vantage of the afterburner.
                                                      VI - 16

     Operating practices have noticeable effects on emissions
t.v.1..   The use of wood or paper produces for igniting the coke
hed results in smoke during this part of the operating cycle.
FluctUating burden height can result in higher mission rates^
Coke and limestone should be handled carefully  to  li.it degrad
tion, and should be  screened prior  to weighing  in  order to limit
che  addition  of dust to the  charge.   Shotblasting of foundry
returns  and cleaning of oily scrap 111 result  in lower missions.

      It has been theorized that design of the cupola can  have
 an effect on the type and quantity of paniculate emissions.
 An objective of the study was to determine whether  test  data
 analyzed on  this basis  substantiate the  theory.   The effort
 expended to  investigate possible  relationships between e^s-
 Si0ns  levels and  cupola design  includes  the identification of
 32  design  classifications representing a large majority
 of  cupola installations in this country, the visits to found-
  rles representative of these classifications, and collection
  of detailed design, operating and emissions data.   "~™
  daca for  this analysis are shown  in the  table  on the
  page.
                                                                                                       T KEARNEY & COMPANY.

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                                               VI  -  17
Sources of Foundry Data for Determination of  Effect
    of Cupola Design Parameters  on  Emissions	
         	Melting Systems
                    Electric
         Cupola     Induction
Electric
  Arc       Total
                      (D
              33
               8
Source
Foundry Visits    29
Interview Guide    8
Only A/P Control
  Boards           9         _z_
   Total          46         (D*          	          	
Note:  * This foundry has both electric  induction
         and arc furnaces as primary melters, and
         is counted only once.
     Particle size distribution of cupola emissions  indicated
by both respondent foundries and by installations  reported in
the  literature are tabulated in Exhibit  VI-8.   A definitive
relationship between size distribution and chemical  composition
of emissions has not been discovered in the literature search,
nor  is Investigation of the possible relationship  within  the
scope of the study.  It would be expected, however,  on the
basis of other  information, that a high percentage of particles
less than five microns in size would coincide with a finding
of a substantial percentage of metallic oxides.  Similarly,  a
high percentage of  particles greater than 44 microns in size
would correspond to large amounts of Si02 from foundry returns
and  dirty scrap, and combustibles such as coke breeze.
                                                                                                                                 VI  -  18
Analysis of
  Emissions Data
     Cupola design parameters and particulate emission  rates
for 17 furnace classifications are tabulated in Exhibit VI-9.
This is a condensed summary of the melting systems,  reported
in sufficient detail to permit complete classification  of  the
furnaces.  Data from foundries reporting  identical,  or  nearly
identical, emission rates from two or more cupolas  of the  same
classification are averaged and the data  are reported only once
in the exhibit.  This averaging prevents  undue emphasis being
placed on any particular foundry and testing technique. Lining
characteristics, blast air temperature and method of heating,
charge opening, location of gas take-off, and use of after-
burners are considered in the multiple regression analysis to
determine the relative effect of design  parameters on  cupola
emission rates.   In certain cases where  data are  limited  and
furnaces differ only in one or  two  parameters,  forced  compari-
sons  are made.
      The results  of the linear  regression analyses show no
clear relationships between furnace emissions  and any  of  the
cupola design  parameters.  Two  trends,  possibly warranting
further  investigation  in  the  future,  are apparent:
           1.   Eight of  the 12 unlined cupolas  have emissions
above the median  rate  of  20.8 pounds/ton of melt, while the
emissions  of  the  13 acid  lined  cupolas are below the median

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                                                     VI -  19
rate.  The two reported emissions  rates  Cor basic  lined cupolas
permit no conclusions to be drawn  since  one was above and  the
other below the median.
          2.  Those cupolas reported as  using briquettes in
the metallic charges all have emissions  rates greater than
average of all foundries for which emissions rates are avail-
able.

     Exhibit VI-10 portrays two correlation matrices from a
second series of multiple linear regression analyses.  In  this
setice, specific melt rate, specific blast rate, metal to coke
ratio, and blast temperatures are  compared to particulate  emis-
sions to determine the possible existence of correlations.  The
following units are employed in the analysis:
          1.  Specific melt rate - Melting rate in tons per
hour per square foot area of the melting zone.
          2.  Specific blast rate  - Blast rate in standard
cubic feet per minute per square foot area of the melting zone.
          3.  Metal to coke ratio  - Pounds of metallic charge
per pound of coke charge.
          4.  Blast temperature -  Degrees Fahrenheit.  Exhibit
VI-11 tabulates the data for the variables used in the analyses.

     The first matrix is the result of data from acid lined
cupolas and the second from unlined cupolas.  Insufficient
data are reported from basic lined furnaces to permit a similar
analysis for this classification.
                A T KEARNEY & COMPANY. INC
                                                                                                                                   VI - 20
     The acid lined cupola matrix  indicates  a  significant.
correlation between emissions and  blast  rate expressed by
the formula
          E = .05 + .07 B
where E = particulate emissions  in pounds  per  ton of melt,
and B = specific blast rate  in SCFM per  square foot furnace
area.  The line represented  by this equation is shown on
Exhibit VI-12.
     The matrix indicates that specific  blast  rate provides
the best correlation with particulate  emissions of all varia-
bles considered, followed by specific  melt rate,  blast air
temperature, and metal to coke ratio in  descending order.
     The regression analysis program,  after  calculating the
correlation index of the individual variables, calculates  the
combined index of the two variables with the highest individual
indices.  The process is continued by  adding variables one  at a
time in descending order of  their  individual indices until  all
have been included, or until the index Improvement by the ad-
dition of one fails to increase  the combined effect by a sig-
nificant amount.
     In this case, the correlation index of  0.6530 for specific
blast rate is not improved significantly by  the inclusion of
specific melt rate in the analysis.  This  implies that specific
melt rate is not an important factor in  the  generation of par-
ticulate emissions.

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                                                      VI  -  21
     The second correlation matrix listed on Exhibit  VI-10 Is
for unllned cupola data and Indicates a significant correlation
between emissions and the two variables, coke rate and specific
blast rate, expressed by the formula
          E •» 57 - 6.6 C + 0.1 B
where E = participate emissions In pounds per ton of  melt,
C - metal to coke ratio,  and B - specific blast  rate  in SCFM
per square foot furnace area.
     The regression analyses indicate that specific blast rate
has a significant effect on emission rate for both  acid lined  and
unlined cupolas.  Coke rate, however, is of greater importance
than blast rate for unlined cupolas and insignificant for acid
lined cupolas.  No reasonable explanation can be offered  for this
difference between acid lined and unlined cupola emissions.  Ad-
ditional observations could possibly show a stronger  correlation
between coke rate and emissions for acid lined cupolas.
     Oxygen  enrichment and natural gas  fuel injection have been
presented  in recent  years as  techniques  to reduce coke require-
ments, or  to increase melting  rates when using the same metal
 to coke  ratio.  These techniques have been partially accepted
by the industry because of their substantial advantages but
 little research and  development work has been done to date
 that establishes  their effect  on cupola  emissions.   It is
possible at  this  time to  report on only  one research effort
 for oxygen enrichment and one  for gas  injection.  No broad
 conclusions  can be drawn  from these  limited data, but trends
 demonstrated are  believed to  be valid.
                                                      VI - 22

     Over 20 cupolas are identified In the general foundry
data as making use of oxygen enrichment to increase  the  total
Oj content in the blast air from 21% to 257., commonly reported
as 4% enrichment.  Only one foundry, however, has reported
emissions levels with and without the use of additional oxygen
as follows:
          Emissions with 4% 02 enrichment - 1.84 gr/SCF
          Emissions without 02 enrichment -  .71 gr/SCF

     These emission levels are reported for an 88-inch lined
diameter cold blast, acid lined cupola melting 52 tons per
hour with an exhaust gas volume of 40,000 SCFM and a coke
rate of 9.3 to 1.  The data are inconclusive since they are
not complete, but they do show an increase in emissions re-
sulting from oxygen enrichment.  Information from other  sources
indicate that although total emissions are increased, the
improvement in the melting rate with oxygen enrichment results
in a slightly lower emission rate per ton of metal melted.
Additional testing is required to definitely establish the
effect of oxygen enrichment on emission levels.
     Several research programs are currently in progress  to
determine the effects of natural gas injection as a  replace-
ment for part of the coke charge.  The results of one such
program  are shown below.
                    Coke
Burner Height    Replaced with    Production    Emissions
   Inches         Cas Percent      Tons/Hour    Pounds/Ton
_
50
50
0%
30
40
14.8
20.1
20.3
67.8
57.1
58.5

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                                                    VI - 23
     The tests were run on a 90-inch diameter, cold blast
cupola lined to 72-inch diameter,  using a 4,000-pound metallic
charge, 600-pound coke charge and  130 pounds of limestone.
During the tests, the blast air was  kept constant at 8,000
CFM, even though coke was replaced by natural gas on equivalent
BTU content basis.  The combustion air for  the gas was provided
stoichiometrically at a 10 to 1 ratio.  The data show decreases
in stack emissions of 15.75% for a 30% reduction in coke
charged, and 13.7% for a 40% reduction in coke charged.

     The emission rate of 67.8 pounds per ton reported for
the control condition with no coke replacement is several
times higher than shown in Exhibit VI-12 for a specific blast
rate of 272 CFM/SF.  Two special conditions, one inherent in
the test program and the other a factor of  weather conditions,
could account for the discrepancy.
     First, in the cest program, the blast  air was held constant
at 8,000 CFM although the coke charge was decreased by as much
as 60%.  This quantity of air was  further increased 36.5% by
the natural gas and combustion air for replacement at 30% of
the coke charge and 54.8% by the gas and air for the 40%
replacement.  It is reasonable to  expect this increase in
gas volume to augment entrainment  of sand and small coke
particles thereby increasing emission rates.  Second, in answer
to a query regarding the unusually high reported emissions,
                                                                                                                                   VI  - 24
the author reported  that the tests were  performed at a time
when the scrapyard was wet and muddy  resulting in the proba-
bility of significant amounts of soil adhering to the scrap
charge, thereby adding to the stack emissions.

     Although the emissions appear to be excessive,  the data
can be accepted as demonstrating the  relative  effect of the
injection of natural gas on emissions levels.
     The injection of other hydrocarbon  fuels  including coal
and fuel oil has been reported in the literature.  Less im-
portance is attached to these efforts than  the injection of
natural gas, and no data pertaining to the  effect of these
fuels on emissions have been reported.

Discussion of Results
     (a)  Introduction
     The effect of a number of variables on the  type and quantity
of cupola emissions has been evaluated by the  use of a variety of
analytical techniques.  These variables  include  the  following:
          Cupola Design Variables
              Lining - acid, basic, or unlined.
              Blast Temperature - cold,  warm or  hot.
              Blast Heating - external or recuperative.
              Charging - side or top charge.
              Gas Take-Off - below charge,  above charge, top
                               of stack
              Afterburner - with afterburner or  without after-
                              burner

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                                                     VI  -  25

              Charge Door - open or closed.
              Fuel Injection - wlch or without  fuel injection.
              Oxygen Enrichment - with or without  oxygen
                                    enrichment.
          Cupola Operating Variables
              Specific Melting Rate
              Specific Blast Rate
              Metal to Coke Rate
              Blast Air Temperature
The analyses demonstrate that some of these  variables have strong
and quantifiable effects and others have statistically insig-
nificant effects on emission devices.  Six of the  variables
evaluated show evidence of the existence of  relationships  but
lack of data prevents determination of the degree  of correlation.
Finally, for two variables, no proof of correlation can  be found,
although logic demands that a causal relationship  exist.

     (b)  Variables with
          Proven Effect
          on Emissions
     The established correlation between emission  quantities
and coke rate suggests that any operating procedure resulting
in changing the coke rate will affect the quantity of partic-
ulate emissions.  This includes heating of the  blast air and
oxygen enrichment or fuel injection with an  attendant decrease
in the coke requirement.  The analysis for unlined cupolas
calculated the effect of coke ratio and specific blast rate
on emission quantities as E = 57 - 6.6 C + 0.1  B.   If only
                A T KEARNEY & COMPANY Ivr
                                                        VI - 26

the coke rate is considered,  the relationship is E = 106.4 - 8.6 C.
The index for the latter is lower than when both variables are
considered jointly, but the equation can be used to approximate
the single effect of coke rate on the emissions level.  This
effect for unlined cupolas is to decrease emissions by 8.6 pounds
per ton of melt for each unit increase in the metal to coke ratio.

     It is not possible to state the exact effect of oxygen
enrichment in conjunction with changes in the coke rate be-
cause of limited data.  It appears probable that the potential
beneficial effect of the increase in coke rate permissible with
four percent enrichment will be partially offset by an  increase
of very small,  difficult to collect metallic oxides,  resulting
from increased  oxidation in the melting  zone.
     The injection of natural gas with combustion  air provided
at a 10 to 1 ratio does not alter Che oxidizing atmosphere  in
the melting  zone.  It would therefore be expected  that  emission
rates with gas  injection would  approximate  the  results  of the
regression analysis  as  the coke charge  is decreased,  for a
constant blast  air to  coke ratio.
      The  decrease  of coke  in  the  charge, while  beneficial from
 the  standpoint  of  emissions  rates and overall melting cost,
 presents  some metallurgical  problems  that must  not be over-
 looked.   The coke  in addition to  providing heat for melting
 also serves  as  a source of carbon often required to meet the
 desired analysis.   This need is minor when the metallic charge
 consists primarily of foundry returns,  cast iron scrap, and

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                                                    VI  - 27

pig iron.  In recent years,  Che increasing cost  of pig iron
has resulted in a shift away from this material  toward steel
scrap with drastically lower carbon content.   This kind  of
charge requires a compensating carbon source  such as graphite
or the substitution of Cabot coke or Carbo-coke  for the  stand-
ard coke.  No data are available to show the  effect of these
materials on emission levels.
     The second major factor bearing a  strong relation to
emission levels is specific  blast rate.   Exhibit VI-11 shows
that the specific blast rate varies over a range from 194 to
462 cubic feet per minute, per square foot of furnace area.
Maximum blast rate is determined by the  capacity of the  blower
and Its motor.  Rates below  the maximum  can be adjusted  to
suit the hot metal requirements since a  decrease in airflow
slows Che coke combustion rate and the melting rate.  Converse-
ly, an increase in blast rate increases  the temperature  in the
melting zone and the melting rate.  The  higher melting zone
temperature will tend to increase vaporization resulting in
greater amounts of metallic  oxides, and  the increase in  air-
flow rate will increase its  entrainment  capability.

     Specific blast rate gives no indication  of  the maximum
rate of gas flow in the cupola, which is strongly affected by
channeling within the burden.  However,  it is reasonable to
expect that as the blast rate increases, the  maximum potential
gas flow rate will be directly affected, increasing the  cap-
ability for entrainment of particulate matter.
                A T KEARVFY & fOVPAVY
                                                       VI - 28

     (c)  Cupola Design
          Variables
     The analyses show that cupola  emissions  rates are not
significantly affected by design  factors  of the furnaces with-
in the parameters established by  current  United States design
practices.  These factors include the method  of blast heating,
top or side charging, charging door size  and  whether or not
the opening is closed or open, the  location of  the gas take-
off above or below the door, or an  open stack permitting Che
gases Co escape out the top.  In  addition,  no significant
effect on emissions rates was found for specific melting rates.
     (d)  Variables with
          Probable Effect
          on Emissions
     Quantitative determination of  correlation  has not been
possible from the available data  for six  factors showing prob-
able effect on emissions levels.  Results of  test programs
have been presented for oxygen enrichment and fuel injection,
but additional data are required  for quantifying the effects
of these practices.  Comparison of  emission data from cupolas
with charges including briquettes,  or not including briquettes,
shows that wich ocher factors being equal,  the  use of bri-
quettes results in larger emissions rates.  Examination of
emissions from acid brick lined cupolas shows lower average
levels than do unlined cupolas but  it is not  established
whether this condition results from the acid  lining icself or
Che fact Chat coke races are generally higher for lined cupolas.

     A condicion difficult Co assign quantitative values to
                                                                                                  A T KF^RVFY * r o M P» W

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                                                      VI  -  29

is the degree of degradation of coke and limestone when these
materials are charged.  Care in handling, degree of weathering,
and efficacy of screening, when done at all,  are all factors
determining the quantity of breeze and dust charged into the
cupola.  There is general agreement that a direct relationship
exists between the quantity of fine particles of these materials
in the charge and cupola emissions.  Only visual observation of
stack plumes bears out Che supposition, since no test data are
available for positive verification.
     A final variable with a strong indication of a causal
relationship perhaps requires no proof of existence--that of
the presence in cupola emissions of nonferrous oxides result-
ing from charge contamination.  The quantities of oxides of
zinc,  lead, tin, copper, manganese, and  the  like can only
derive from contaminants  or alloying materials in the metallic
scrap  charge.
      Even  though scrap is purchased to specification, and
 Che analysis is quoted by the  dealer,  it is  possible that
 significant quantities of undesirable  alloys or contaminants
 can be included  in a  shipment.   In many  cases, the  existence
 and quantity of  these materials  can be determined  only by  an
 analysis of  the  cupola emissions,  slag,  and  iron.
      It  would  pose an almost  impossible  probe 1m  to  obtain  a
 completely representative sample of scrap charge  to determine
 a relationship of  composition of input to that  of  the  col-
 lected particulate matter.   There are  strong indications  that
                 A T KT^PS'FY ft fOMP^VY
                                                      VI - 30

inclusion of burned-m sand on foundry returns and dirt from
the scrapyard results in increased S102 concentrations in the
emission.  Here again the collection of data is extremely
difficult—both the determination of the quanciCy of sand in
the charge and Che discribuCion of the sand in Che particulate
emissions and the slag.  A similar indication of probable
correlation, without sufficient data Co establish an index
of correlation, exists for the scrap metal thickness and
degree of surface corrosion with iron oxide concentration in
cupola emissions.  The problem again relates to the difficulty
of measuring corrosion and determining a reasonably accurace
figure for surface area per unic weighc of Che metallic charge.
Exhibit VI-14 shows Che approximate surface area per ton and
pounds of rust per ton for various ferrous scrap materials.
An additional uncertainty exists in the amount of iron oxide,
if any, converted to elemental iron in the reducing zone and
melted, or being trapped in the slag.

     (e)  Variables with
          Expected Effect
          on Emissions
     Two variables expected to show large indices of correlation
with emissions levels surprisingly did not.  Blast temperature
shows in Exhibit VI-10 an expectedly high correlation of 0.874
with coke rate, indicating that the percentage of coke in the
charge is usually decreased when the blast temperature is in-
creased.  Unpredictably,  however, neither the coke rate with
an index of 0.223 nor the blast temperature with an index of
0.294 correlated strongly with emissions levels.  For unlined
                                                                                                A T KF«iR"-'FV ft

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                                                      VI - 31

cupolas, practically no correlation exists between blast rate
and any of the independent  variables or  the emissions level.
No justification for this situation can  be established.

     No decrease in emissions clearly  attributable to the use
of afterburners was recognized by  the  analyses.  A properly
designed and installed system of afterburners will,  in addition
to burning carbon monoxide  to carbon dioxide, reduce combus-
tibles to ash, provided sufficient oxygen  is available and
the residence time is long  enough  for  complete combustion.
The unexpected lack of correlation between the use of after-
burners and emissions level can only be  explained by one or
more of the following:
          1.  Afterburner not large enough or improperly
installed.
          2.  Afterburner not operating  at time of reported
tests.
          3.  Insufficient  retention time.
          4.  Insufficient  oxygen.
          5.  No combustibles in stack.
The last two items are highly improbable,  but any or all of
the other alternatives are  possible.

     (f)  Conclusion
     The lack of correlation between standard furnace design
factors and emissions levels requires  that the explanation
for the wide variance in type and  quantity of emissions lies
with cupola operating factors.  This is  borne out by the fact
                  T i, r \ o v r v q, rn v p \
                                                      VI  -  32

that all variables proven to affect emissions  levels, or  in-
dicating a probability of affecting emissions  levels, relate
more to the operation of the cupola than  to  its  design.   These
operating factors can be easily divided into two quite  distinct
groupings with some cross effects  from one group to the other

     The first group consists of variables related  directly  to
cupola operation, including specific blast rate,  blast  tem-
perature, type of lining, and operating variables of the  after-
burner.  The afterburner itself is an emission control  device
but adjustment of gas and combustion air  is  considered  here  as
a variable for the melting system.  These variables are rela-
tively inflexible and are determined by required, or desired,
operating characteristics.
     The second group of variables concerns  the  quantity  and
quality of charge materials.  These include  coke rate,  oxygen,
natural gas, coke and limestone dust, briquettes often  contain-
ing oil or cementitious materials, and contaminants or  alloying
materials in the metallic charge.  These  factors are highly
variable, often from minute to minute, and are more controllable.

     Insufficient data prohibit the quantitive evaluation of
the total effect of all variables  in the  first group compared
to all variables in the second group.  The data  suggest,  how-
ever, that the type and quantity of cupola emissions are
affected more by the quantity and quality of charge materials.
Certainly little or no limestone dust, coke  particles,  or oil
vapor and other combustibles will appear  in  the  emission  unless
                                                                                                    A T K F. * R V F Y A r O M I • \ VV I v r

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                                                      VI - 33
these materials are charged Into the cupola.   Similar  state-
ments can be made for zinc, lead,  aluminum, chromium,  cadmium,
copper, silicon and other oxides,  particularly when  their  for-
mation is abetted by the injection of oxygen,  or high  blast
rates.
     Certain relationships expected to be  identified by  the
analyses were not discovered.   Blast air temperature,  with a
demonstrable effect on coke rate,  was expected to show a
secondary effect on the emissions  level.  The  use of after-
burners in the cupola stack has been shown to  aid in the in-
cineration of combustibles, the result of  which would  be to
lower the emission levels to at least a noticeable degree.
The fact that these relationships  were not identified  might be
attributed to two factors possioly affecting all the analyses:
the quantity and quality of the test data.
     The limited availability of data has  been documented, as
well as the reasons for the short supply.   The variable  quality
of Che information is due first to the lack of understanding
by foundry operators of the accuracy required  of data  for
analytical purposes, and second to the several stack testing
techniques in use by different testing laboratories.  Where
possible, questionable data were confirmed, and if verification
was not possible, the data were discarded. The greater  problem
is in the results of stack sampling tests.
     Stack testing is not an exact science at  this time  and no
single technique has been accepted by the  industry.  Methods
and equipment used to obtain the data listed  in the  foundry
                » T i r > p M F v (v r- n v P * w i v <•
                                                      VI - 34

data bank have been discussed earlier.  Repeatability of re-
sults is difficult with any given technique by a single testing
firm, even for & stable emissions producing system.  With
relatively unstable conditions in cupola furnaces, and the
generally poor working conditions existing at the top of
cupola stacks, variation in results would be expected.  With
this situation further compounded by  the use of different tech-
niques, equipment, and testing companies to obtain data for
comparison and analysis, the confidence level of the data must
suffer, despite the high degree of professionalism of the
laboratories performing the tests.  As a result of this con-
dition, all data used in the analyses have undergone critical
evaluation before acceptance.  Even with this method of re-
viewing data, it is believed that identification of less strong
relationships might be missed  in the  evaluative processes,  and
that only strong relationships will be recognized.
     The problem of comparing  stack test results obtained with
different test procedures  is expected to end with  industry
acceptance of the recently published  "Recommended  Practice  for
Testing  Particulate Emissions  from  Iron Foundry  Cupolas."   The
procedure was developed by a joint  industry committee  sponsored
by  the American Foundrymen'a Society  and the Gray  and  Ductile
Iron Founders' Society, Inc.   The committee  investigated  the
theorectical  and practical aspects  of stack  testing and held
discussions with representatives  of the various  testing lab-
oratories to  gain additional  insight  before writing  the pro-
cedure.
                                                                                                         A T KE-iRVFY * COMPANY

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                                                      VI - 35


     The recommended practice,  included in Appendix  E,  is
based upon the American Society of Mechanical  Engineers
Performance Test Code 27-1957,  Determining Dust Concentration
in a Gas Stream with certain modifications to  satisfy  the
special conditions existing in  the iron melting cupola  instal-
lation.  Three special conditions  are  identified  as  follows
and recommended test procedures are established for  each:
          1.  Sampling raw particulate emissions  in  the  cupola
stack where gas flow fluctuates, flow  rate is  low, gas  tem-
perature is high, and dust loading is  extremely uneven.
          2.  Sampling raw particulates emissions  in the inlet
duct to the dust collector where velocities and loadings are
more uniform, flow rate is greater,  temperatures  are more
moderate, and humidity is high.
          3.  Sampling cleaned  gases at the dust  collector
outlet where velocities and flow rates are nearly  uniform,
and dust loadings are low.

EVALUATION OF EMISSIONS
  FROM OTHER SOURCES
     Although the cupola has been  considered to be the princi-
pal source of iron foundry emissions which are difficult or
costly to control, there are other areas in the foundry  which
also produce these types of emissions.  The earlier  discussions
in this report covered the equipment and operations  in the iron
foundry which produce emissions.  Some of these have been  ad-
equately and economically controlled with existing designs of
               A  T KEARNEY & COMPANY. IMC
                                                      VT - 36
equipment, while others have proven  to present  problems which
have not yet been completely solved.  In  Exhibit  V-l,  chcse
emissions sources are classified according  to  the case and
economy with which they can be controlled.
     The ease and cost of controllability can generally be
related to two broad aspects:  the problems  which relate to
capturing the emissions with a minimum of infiltrated  air and
the problems of adequately removing  the fine particles and
gases from the capture medium before their release  to  the atmo-
sphere.  In general, those operations which  in  many foundries take
place in open, nonconcentrated, nonstationary locations are
difficult to control although, in many cases, the actual coses
of control may not be high once the  emissions are captured.
These operations take place in the scrapyard, mold  pouring area,
and the shakeout area.

     The other areas w'.iich involve difficulty  of  capture and
high cost of control equipment include arc melting, magnesium
treatment to produce ductile iron and coremaking,  The dis-
cussion in this section concentrates on these areas.

     A general problem encountered in analyzing these  areas,
other than the cupola, is that relatively little  quantitative
information is available regarding the quantity and nature of
emissions generated.  As a result, much of  the  data in the
following paragraphs were developed  by analytical methods
                                                                                                  A T KEARNEY & COMPANY I x e-

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                                                      VI  -  37
and by adaptation from similar operations  in  other  Indus Cries,
racher Chan from accual field information.

Eleccric Arc
  Me1Cing and
  Holding
     The number of electric arc melting installations  in  iron
foundries is relatively small, with less Chan 50 known to
exisC in 1959, and approximacely 200 in 1969.  This is a  small
faccor when compared with che cupola.   However,  Che Crend co-
ward elecCric melting, both arc and induccion,  is increasing
rapidly, and Che elecCric arc furnace will most cerCainly be
a growing faccor in che iron foundry.

     Because of ics greaCer importance in Che melcing  of  sCeel,
much accenCion has been given Co che emissions problems from
arc melcing in Che sCeel indusCry and in che  sCeel  foundry.
Practically all of Che emissions daCa which have been  gathered
have been in chese induscries as discinguished from che iron
foundry indusCry.  SCeel producclon and melcing in  electric
arc furnaces can be classified inCo Cwo broad groups.   The
first involves basic melting practice in which refining as
well as melcing is performed and in which one or Cwo slags are
formed Co eliminate impurities.  The second involves acid
melcing practice, in which almost no refining is done  and in
which only a minimal slag is produced.
     Acid sceel melcing is very similar Co iron melcing in Che
arc furnace, with che principal difference being che common use
                                                      VI  -  38


of oxygen  injecced inCo Che molcen  sCeel  as  a  means  of rapid
reducclon  of carbon content, while  iron  is melced without  che
use of oxygen and, in face, usually must  have  the carbon con-
Cent raised by carbonaceous additions.  With che excepcion of
Che gases  evolved during oxygen  lancing,  che emissions evolved
in both Cypes of acid melcing are similar.

     The emissions from iron melcing  in  Che  arc  furnace  come
from Cwo principal sources--the  burning or vaporization  of
combustible materials which may  be  in the charged raw materials,
and the burning of the electrodes and some of  Che charge metal-
lies during meltdown.  In both cases,  the greatest evolution
of gases occurs during the early part of  the cycle,  when melt-
down takes place and when the electric power consumption is
highest.  Although the type and  quantity  of  emissions from
combustion of impurities in the  charged maCerials is highly
variable depending on Che nature and  cleanliness of  Chese
materials, Che gases produced from  combustion  of Che electrodes
are a known and comparatively conscanC and calculable source
of emissions.  Approximacely 9-11 pounds  of  electrodes are con-
sumed per  con of iron melted, producing approximacely 30 pounds
of CO and C02 gases, plus 150 pounds  of N'2 which comes from the
air induced inCo che furnace.  Additionally, a small quanCiCy
of Che mecallics,  principally iron, is oxidized  and  emitted as
oxide fumes.
                                                                                                  A T KF«iRVEY * COMI'\VY

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                                                     VI - 39

     Four of Che iron  foundries visiced during the course of
this study were electric  arc melting  installations, all having
fabric filter collectors  for emission control.  Samples from
the collectors of three of these were anlayzed for particle size
distribution and for chemical  analysis.  The results of these
tests, together with reported  emission rates per  ton of iron
melted, are given tn Exhibits  VI-15 and VI-16.  Data on the
furnace sizes and dust collector  system size are  also given.

     Although the collected data are  insufficient for Che
type of analysis which was conducted  for Che cupola, they can
be combined with other uata for acid  steel melting as well as
iron melting Co form cerCain general  conclusions.  Exhibit
VI-16 gives these additional results  for a variety of installa-
tions ranging from 2-  to  25-ton capacities, all melting in aci v

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                                                       VI  -
 representing about 10% of Iron Connage  cast.   Despite  this,
 there has been relatively little information  gathered  regarding
 the nature and quantity of emissions produced during this
 practice.  The treatment agent is commonly a  form of magnesium
 which can be introduced into the molten iron  to produce the
 desired effect.  Exhibit VI-18 illustrates the various methods
. by which this can be accomplished.
      The reaction produced during the magnesium treatement
 process is a violent one, but of short  duration, although
 the degree of the violence varies with  the form and method
 of introduction of the magnesium.  Because of this, only a
 relatively low percentage of the magnesium which is introduced
 is actually involved in the reactions which produce ductile
 iron.'Vh-L'.i .-lie remainder being vaporized and expelled as a
 fume.  The actual yields vary from as low as  15% to as high  as
 75%, depending on the treatment agent used and the rapidity
 with which it is added to the iron bath.  The yield factor which
 is most generally accepted is about 30% to 357..
      Although several ductile iron foundries have installed
 emissions control systems on the treatment stations, none  has
 attempted to measure the quantity of emissions per ton of  iron
 treated, or to analyze the emissions to determine the particle
 size distribution or the chemical composition.  The analysis,
 therefore, is based on an analysis of the known reactions
 which occur, and the normal yields which are expected during
 the process.
                 A T KF \RS-FY S. TOMPIXY 1 - r-
                                                                                                                                        VI  - 42
     Magnesium is the principal agent resulting in emissions,
since the alloying materials which are used as carriers of
the magnesium either dissolve in the iron or oxidize  to form
slag.  A major exception to this is the use of magnesium  im-
pregnated coke which evolves CO and C02 gas as well as MgO
fume.  The boiling point of magnesium is about 2,025° F,  which
is well below the temperature of molten iron and accounts for
the violence of the reaction which takes place.  The  magnesium
in the inoculant is used up in three ways:
          1.  Some magnesium will react with any sulfur pre-
sent to form MgS, and become part of the slag.  Although  iron
which is to be used for ductile iron production is generally
pretreated with a basic material such as Na2C03 or CaC03  to
remove sulfur, there is usually about .02%  to  .03% of sulfur
remaining.  This will be effectively eliminated by the mag-
nesium, using about 0.5 pounds of magnesium per ton  of  iron.
          2.  A small quantity of magnesium will dissolve in
the iron, to the extent of about .04%.  This amounts  to about
0.8 pounds of magnesium per ton of iron.
          3.  The remaining magnesium will  boil off,  forming
MgO upon contact with the air.  The amount  of  magnesium added
will vary from 0.12% to 0.30% of the iron  treated  or from 2.4
to 6.0 pounds of magnesium per ton of iron. Deducting  the
1.3 pounds of magnesium which was consumed by  sulfur reaction
or dissolved  in the  iron leaves from 1.1  to 4.7 pounds  of
magnesium per ton of iron treated to form  MgO  fume.   This
will result  in about 2  to 8 pounds of MgO  fume generated  per
ton  of  iron  treated.

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                                                 VI - 43

     The  fume from the magnesium treatment process will be
largely MgO, with this material accounting for from 60% to
80% of the total, depending on the form  In which the magnesium
was Introduced and the violence of the reaction.  The more
violent reactions, particularly when silicon-magnesium alloys
are used, will also produce SlOj particles In the emissions.
Iron oxide, as Fe203, will also be found in the emissions and
will constitute the second most important material present,
after MgO.

     Particle size of the emissions will be fine  for the MgO
and Fe203 portions, with the silica and  alumina particles
generally of larger size.  These particles are under or>°
micron in size and are difficult to collect,  requiring the
use of fabric filters or high energy wet scrubbers.
     Exhibit VI-19 gives the reported results from the magne-
sium treatment station of a large gray and ductile iron foundry.
This station was used for ductile Iron treatment, desulfuri-
zation and ferrosilicon inoculation, which explains the pre-
sence of  such elements as sulfur and calcium in the catch.
The amount of magnesium in the inoculant was 2.25 pounds per
ton of iron treated.  At a yield of 35%, this resulted in 1.45
pounds vaporized, giving 2.4 pounds per  ton of MgO.  This
amounts to 73% of the emissions actually captured.
Mold Pouring
  and Cooling
     Molding sands consists of silica, zircon,  olivine, chamotte,
and occasionally other mineral grains bonded with clay, ben-
tonlte, Portland cement, plaster of paris, petroleum residues
               A T KEARNEY & COMPANY Ivr
                                                                                                                         VI - 44
                                     wood
r:~=~



Wood flour
Sea coal
Cereal binder
Silica flour
                                      0.5%-
                                      2.5%- 8.0%
                                      0.5%- 1.0*
                                      0.0%-15.0%
                                      :r:::— rr
   into the surrounding atmosphere.  The natur
                          -20.  While these data refer to

    :;::::;:,;;«
                                                                                                                              -
                                                                                            A r K ¥

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                                                      VI  -  45

from decomposition of water vapor,  while the CO comes  from
combustion of organic materials.
     The volume of gas formed is  illustrated in Exhibits  VI-21
and VI-22, for various mold materials.   Gas evolved ranges  from
74.4 to as high as 824 cubic feet per cubic foot of sand  at
1,800° F.  Only a small portion of the  sand adjacent to the
sand-metal interface approaches this temperature and gas  forma-
tion drops off rapidly as the distance  from the interface in-
creases.  Although relatively small amounts of participates are
involved, the potential toxicity  of the unburned combustibles makes
collection an important factor.  The high temperatures associated
with pouring often result in burning of gas as it leaves  the
molds.  This afterburning is desirable  to completely convert the
combustibles to COj and water vapor and to eliminate explosion
and toxicity hazards, particularly if the mold contains oil sand
cores.
Coremaking
     Emissions resulting from coremaking operations are general-
ly in the form of vapor, dust and gas,  the type and amount  depend-
ing on the nature of the core mix and the coremaking process.
The core mix is typically comprised of  silica sand, binder  and
moisture.  The binders used in coremaking include linseed oil,
core oil, wheat flour, sulphite,  pitch, oiless binders, resins,
silica flour, fire clay, wood flour, iron oxide,  bentonite,
and silica sand.
                A T KFM«N-EY et COMPAN-Y
                                                       VI  -  46

     Core binders that generate a considerable volume  of  gas
on pouring of the mold are undesirable.  A  typical  core mix
for malleable iron castings might be as  follows:
     Sand       Cereal     Moisture      Oil      Binder
   92%-98    .75%-!. 257.     0%-57.        07.-17.    0%-,5%
     Core mixes for gray iron castings vary greatly according
to Che general size of the casting and the  specific application
for the part.  The rate of gas volume generated  in  a core
during the pouring process is largely a  function  of baking
time and temperature.  Exhibit VI-23 illustrates  the effect of
baking time on the volume of gas generated  at various  baking
temperatures.  A review of the curves quickly points out  that
the gas content is reduced by baking at  higher temperatures.

     Resin binders of the type normally  used  in shell  cores
present varying degrees of hazards due to the toxicity of the
decomposition products.  Dermatitis is the  principal effect
caused by an excess of free phenol, formaldehyde, hexamethylene-
tetramine or alcohol.  The extent of the hazard depends upon
the specific agent and the tolerance level  for that agent.
Phenol, for example, can cause dermatitis and do  organic  damage
to the body at levels exceeding five parts  per million.   Form-
aldehyde is a nuisance at levels exceeding  five parts  per
million.  Hexamethylenetetramine can cause  skin irritations
with direct contact.
     Other toxic and irritating materials include furfuryl
alcohol,  ethyl alcohol, methyl alcohol,  urea, carbon monoxide
                                                                                                      A T KFARVEY ft COMPANY  Ivc

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                                                      VI  - 47
and silica dust.  These can be released during shell  operations.
Each has varying minimum levels of concentration  before  Its
toxicity or Irritation are critical or a nuisance.  Ventila-
tion becomes the important factor in minimizing these hazards.
The sand to oil ratio has a bearing on the volume of  gas
generated in a core during pouring.  The effect of  sand  to
oil ratio on the amount of core gas given off  during  pouring
is Illustrated in Exhibit VI-24.  The relative amounts of
gas produced by various core binders is given  in  the  following
table.
           Core Binder
           Linseed
           Petroleum
           Urea resins
           Cereal
Cubic Centimeter
 Gas per Gram
 380 - 450
 350 - 410
 300 - 600
 550 - 660
                 A T KEARNEY 8= COMPANY, lie
                                                                                                                                         VI - 48
                                                                                                            REFERENCES
                                                   1.  Foundry Air Pollution Control Manual.  American
                                              Foundrymen's Society, 1967.
                                                   2.  jr,n-
                                                                       Anoaratus. American Society of
Mechanical Engineers, PTC 21-1941.
     3   "Influence of Melting Method  and  Charge Composition
on Cupola Effluent," Mark M.  S.  Chi and F. EKman, paper pre-
sented before  1970 AFS Casting Congress and Exposition,
Cleveland,  Ohio.
     4.   -,.T-i~*— tstaubunK.  G. Engels and E. Weber,
 Giesserie-verlag G.m.b.H. , Dusseldorf, translated by  P.  S.
 Cowen, Gray and Ductile Iron Founders' Society,  Cleveland,
 Ohio.
      5   -Gas injection Lovers  Cupola Melting Costs,  Increases
 H.ltin. Rates," J. A. Davis, e^al, J-ndrv,  June,  1969,
 pp. 66-73.
      6    "Readers  Comment.  Letter from Institut fur
  CiessereitechniU," Dusseldorf,  Germany, Foundrv, December,
  1969, p.  «.
                                                                                                     A  T  KEARNEY & COMPANY. I

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                   VII - TECHNICAL ANALYSIS OF
                   EMISSION CONTROL TECHNOLOGY
ANALYSIS OF EMISSION
  CONTROL TECHNIQUES
     Over the years, increasing attention to foundry and other
industry sources o£ emissions has prompted development of
many types of equipment for control of the emissions from
these sources.  As the significance, complexity and scope
of the  problem grew, new designs were introduced or existing
ones modified.
     The problems arising from each type of foundry emissions
and the equipment best suited for control vary with the
nature  of  the specific problem.  These systems, which include
dry centrifugals, wet collectors, fabric filters and electro-
static  precipitators, vary widely in design, capacities,
capabilities, cost  and application.

Dry Centrifugal
   Collectors
      (a)   Historical
     	Background
     Low  pressure  drop centrifugal  collectors were  first developed
 In about  1880  to remove dust  from the secondary circuit  of dust
 louvres.   Higher pressure  loss centrifugal  collectors were in-
 troduced  in the  1920's in  Europe.   At about this time,  small
 diameter  cyclones  connected  in parallel were being  used  in the
 United  States.   Although first applied to  boiler fly ash pro-
 cessing,  they  were to become  the usual application  for  grinding
                   T hi « T» V F V ft I- O V V •,
                                                        VII - 2

  and chipping operations.  Design  improvements  increasing the
  collection efficiency were made in  Che  1940's  and  early 1950's
  making it possible to apply centrifugal collectors  to cupolas,
       (b)  General Characteristics
      	of Equipment	
      Dry centrifugal collectors are essentially  low energy
  units operating on the principle of mass force action  on
  individual dust particles.  Gravity, inertia, and centrifugal
  force act to separate the dust particles from an airstream.   It
  is iiroortant that this type of collector operate within design
  limitations  to  maintain proper efficiencies.  If the gas flow
 drops below  normal,  inertia  or centrifugal forces are reduced
 and collection  efficiences are lowered.   Excess moisture in the
 gas stream also results  in reduced effectiveness by clogging
 the system.

      Physical characteristic of the  dust is an important factor
 in the application of centrifugal  collectors.   Particle size,
 shape  and  density determine, in large  part,  the ability of
 these collectors to function properly. The  collection  efficiency
 required for a  particular  application  is also  a major  factor
 in selection of a centrifugal collector.  High  efficiency
 requirements may preclude  the use of this type  of collector
with its limited effectiveness.1

     (c)  Description of
     	Specific Types
     Four basic  types  of dry centrifugal collectors currently
in use are:  cyclone,  high efficiency cyclone, high efficiency

                A T KEARNEY & COMPANY 1 v <-

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                                                      VII - 3

centrifugal and dynamic precipitator.
          1.  Cyclone - This unit  type  is  essentially a conical
chamber with a dirty air inlet on  the periphery, a clean air
exhaust at the top, and a dust removal  opening at the bottom of
the cone.  In a common cyclone design,  contaminated gases are
tangentially led into the unit so  that  a  rotational gas flow
is produced.  The dust particles travel towards the outside and
bottom of the chamber under the influence  of centrifugal force.
The particulate matter enters a collection bin or hopper and
settles, while the cleaned gases,  which also traveled to the
bottom of the cone during the centrifugal  action, leave we
cyclone through a pipe or tube located  in  the middle of the
system.
          The dust collection efficiency of cyclones depends on
the pressure drop which increases  with  the inlet velocity
of the dust gas mixture in the collector.   The larger the pressure
drop, the smaller the Limiting dust grain size, and the higher
the collection efficiency.  As gas velocity increases,  collection
efficiency will increase rapidly.   However, at a-certain point,
a further increase in gas velocity will not raise efficiency by
any noticeable amount.  Collection efficiency of cyclones also
depends on other factors such as the quantity and nature of the
dust, their surface properties, electrical charge and moisture
content.
           Electrical charge is important with regard to submicron
particles.  If emissions are  charged similarly,  they  tend  to  re-
pel each other with the result that collection efficiency drops.
                 A T.KEARVEY & COMP".VY 1 «. f
                                                                                                                                     VII - 4
Conversely, agglomeration takes place and efficiency  increases
when positively and negatively charged particles are  present.
          In addition to the dirty gases being  tangentially led
into the cyclone collector, there are other  input methods  used.
Inlet spiral or axial and radial guide vanes, on the  inlet side
of the dust collector, can also be utilized.    An example  of a
cyclone is shown in Exhibit VII-1.
          2.  High Efficiency Cyclone - This type of  unit  is
similar to regular cyclones in design and operation.   Differences
exist in Che diameter and shape of the two units.   High  effi-
ciency cyclones usually have a smaller diameter chamber  and a
longer cone than regular cyclones.
          Pertaining to the collection operation of these  units,
higher efficiency can be obtained in comparison to  regular cy-
clones.  This is achieved by the increased velocity that exists
with high efficiency cyclone units and greater  centrifugal
force resulting from the smaller diameter.   Energy  requirements
of high efficiency cyclones are somewhat greater than regular
cyclones.  Pressure drop is in the 3- to 6-inch water gauge range
with high efficiency units whereas regular cyclones obtain
approximately a 1.5- to 3-inch level.  With  the greater  energy
requirements of a high efficiency unit, a more  powerful  fan and
drive are needed.
          With these units, dust discharge must be  continuous  to
a dust storage bin that is often equipped with  an air lock or
flap gate discharge device.  Collected dust  must not  be  stored
in the cone bottom since reentrainment and loss of  efficiency

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                                                      VII  - 5

would resulc.  High efficiency units  generally  operate on suction
but can also operate on the pressure  side  of  the  fan.
          Maintenance of these units  requires periodic inspection
of interior surfaces for wear.  The discharge device should also
                                 It
be examined for proper operation.
          3.  High Efficiency Centrifugal  - High  efficiency
centrifugal collectors consist of a series of small cyclone-type
units in a  single housing.  Different designs of  this unit  type
are  available.  One type utilizes swirl rings that help  produce
a cyclone motion in the airstream.  The cleaned air is exhausted
out  the center section of the cyclone and the dust settles  into
a storage hopper.  Another type utilizes multiple tubes  and a
secondary air circuit to achieve a higher collection of  small
particulate matter.  In the operation of this system, dirty air
enters through an inlet that has a slot for maintaining  a uniform
distribution of the air.  The incoming air moves  tangentially  to
provide the cyclonic action to hurl the particles to the outer
periphery of the tube.  The dust and a portion of the primary  air
are  bled off.  The clean air passes out through the end  of  the
tube into a main duct.  Larger dust particles then fall  into a
hopper and  the remaining dust and secondary air are drawn  through
another set of tubes.  The air also enters tangentially  in  these
tubes and the remaining dust particles move outward and  exit into
a hopper.   The clean air passes back through the  center  of  the
tubes and reenters on the inlet side of the unit.  If this  type of
unit is used on cupolas, other equipment such as  cupola  caps,
pressure relief vents, gas burners, cooling towers and high tem-
perature ductwork is required.
                  A T  KK\HM:Y & COMPASS  i^c
                                                       VII - 6

          Due to the high internal velocity of the air, various
component parts may tend to wear.  This requires inspection of
all tubes, wall surfaces and hoppers to assure proper function-
    4
ing.   Pressure drops are in the range of four to six inches
water column, and collection efficiencies somewhat higher than
for high efficiency cyclones.  The small dust outlet size can
be plugged more readily and poor distribution within che
collector can cause short-circuiting within the dust hopper
which will reduce collection efficiency.
          An example of a high efficiency centrifugal unit is
illustrated in Exhibit VII-2.
          4.  Dynamic Precipitator - This dry centrifugal col-
lector consists of three main components:  an impeller, housing,
and a dust chamber.  The impeller's purpose is to move  the
air, guide the airflow and force the dust particles to  the pe-
riphery by centrifugal force.
          The housing has two compartments--one for cleaned
air which comes from the impeller and is projected out  the dis-
charge, and the other for dirty  air which is discharged from  the
impeller.  This dirty air goes into a hopper after which a
decrease in velocity takes place that allows the particles to
settle.  The cleaned air is then returned into the outer compart-
ment.  Collected material is usually emptied from hoppers and
disposed of in the dry state.
          There are modifications which can be made to  the sys-
tem described in the previous paragraph.  If larger particles
or heavier concentrations exist, a skimmer may be used.  The
                 A T KEARNEY & COMPANY I Mc

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                                                      VII - 7

operation of a skimmer  Is  similar  to  that of a low energy
mechanical collector.   In  addition, aftercleaners are sometimes
used if the dust Is  nontoxic.  Aftercleaners assist in removing
small participate matter and  also  allow  filtered air to be
returned to the plant.  Maintenance of the  system is required
                                                4
for such areas as internal surfaces and  bearings.
          An example of a  dynamic  precipitator is  shown  in
Exhibit VII-3.
      (d)  Advantages of Dry
          Centrifugal Collectors
      Certain dry centrifugal designs such as cyclones  and  high
 efficiency cyclones are relatively simple in operation and do
                                    2
 not  require a large investment cost.
      Common cyclones are simple to maintain although inspection
 of portions of the system are required.  Furthermore,  dynamic
 precipitator installations can be modified in the future with
 the  addition of skimmers or aftercleaners.  This permits a
                                   4
 more flexible collection operation.
      Finally, protective devices can be installed on some  designs
                                                          6
 of these  systems to enable gas bypass in case of failures.

      (e)  Disadvantages of
          Dry Centrifugal
      	Collectors	
      These systems are subject to abrasion and therefore require
 periodic  inspection to operate properly.  Common cyclones  require
 inspection usually to a lesser degree than other dry mechanical
 systems because of their larger scale application to coarse
 particle  problems.
                                                       VII - 8

     If dry centrifugal collector systems are not  operated
within their airflow design specifications, collection efficien-
cies achieved will be lower than what  the system is capable of
capturing.  Furthermore, compared to the other three  basic
emission control systems, dry centrigual collectors achieve the
lowest collection efficiency on fine and medium-sized particle
dust.
     With dry centrifugal collectors,  a dry dust disposal
problem exists depending on the type of refuse handling equip-
ment utilized by the particular foundry.  Dry dust is difficult
to wet, and disposal often results in  secondary  pollution.

     Certain systems such as high efficiency centrifugal units,
when installed on cupolas, require additional equipment for
dust handling and disposal which adds  to investment requirements.

     (f)  Limitations of Dry
     	Centrifugal Collectors
     Dry centrifugal collectors have the greatest  limitation
of the four emission control systems under consideration regard-
ing particle size that can be captured.  The smallest particle
dynamic precipitators and high efficiency centrigual  units can
effectively collect is approximately 10 microns  in size.  Common
cyclones have a greater limitation in  that the smallest particle
                                                            4
size they effectively collect is in the 20-40 micron  range.

     These limitations prevent their effective application to
a number of foundry processes.  Dry centrifugal  collectors are
                                                                                                     A T KEIRN'EV & COMPAVY Ivr

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                                                      VII  - 9
not applied to electric melting processes,  mold  cooling,  pour-
ing, core and paint ovens or oil burn-off furnaces.   Finally,
these collection systems are normally not capable  of  operating
at temperatures above 750  F unless special heat resisting alloys
are employed.
Wet Collectors
      (a)  Historical
     	Background
     Wet collectors have been applied in foundries to control
emissions since the late 1930's.  Low energy units were first
introduced,  including the \^~ cap which became popular during
World War II.
     As residential areas developed closer to foundry operations,
nuisance complaints from dust settlements increased.   Conven-
tional medium energy wet scrubbers such as centrifugal units
were introduced in the 1950's to help solve this problem.
     Later,  the public demand for removal of finer particles
from cupolas encouraged the application of high energy scrubbers
such as Venturis.  With the advent of the venturi  scrubber, a
substantial  increase in wet cleaning efficiency was introduced.
      (b)  General Characteristics
     	of Equipment	
     Wet collectors all utilize water, or a water  solution, as
a means of capturing and removing dust particles from an air-
stream.  In  general, three  basic principles are involved:
          1.  Saturation of the Airstream - A wet  collector
must  first saturate the airstream to retain dust particles
                  A T KEIRN'EY 8t COMPANY  INC
                                                       VII  - 10

captured.   If  the water use 1  for  collection is allowed to cv.ipn-
ratc,  the dust patticles w. ..1  be  released.
          2.  Wetting - Wetting of  dust  particles  is necessary,
since  the particles cannot be  captured unless  their surface is
wet.
          3. Separation - After thorough wetting jnd i.ipi.in
of the dust, the water droplets containing  the dust  particles
are separated from the airstream.

     Wet collectors can safely handle high  temperatures,  iijjli
moisture cgntent and fine clay bond particles  without obstruc-
tion to air moving or particle collective functions.   Further-
more,  this  type is most practical for foundries having an  exist-
ing supply of low cost water and  the ability to dispose of col-
lected waste in slurry or sludge  form.   In  fact, collector de-
signs will be determined to a considerable  extent  by the foundr<<
water  supoly and water clarification system being  employed.  Urn
systems will incorporate self-contained water  circulating  systems
with either integral or auxiliary settling  tanks for dewatering
and removing collected sludge.

     For large production foundries, central sluicing systems
are sometimes employed to eliminate multiple disposal points
and in-plant haulage of the collected sludge.   Collectors  drain
continuously to the sluicing system.  Collected material is
settled out in large settling tanks or tailing ponds  with  water
usually recirculated after clarification.
                 A T hEARNEY & COMPANY IMC

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                                                        VII  -  11
      (c)  Description of
      	Specific Types
      Seven specific types of wet collectors used are:   static
washer, dynamic precipitator, centrifugal,  orifice,  centrifugal
spray, flooded bed and venturi.
          1.  Static Washer - Static washers,  the siiiplest  form
of wet collectors, are used where moderate  to  heavy  concentration
of dust particles and lower efficiencies are expected.   This
design usually consists of a shell or housing  containing banks
of water  sprays, simple scrubber plates, additional  sprays, and
moisture  separators.  Spray towers or stacks equipped with water
sprays fall in this classification.  The lower section  of the
collector is cone-shaped to collect and drain  the collected
liquid.   Additional equipment required for  these collectors in-
cludes pumps and/or piping for circulation  of  water, a  means of
disposing of the collected sludge and fans  in  all cases except
the wet cap which relies on natural draft.   The basic principle
for cleaning with a static washer is that the  dirty  gases come
in direct contact with sheets or sprays of  water which  flow in
the opposite direction of the gases.
          The most common type of cupola static  washer  is a wet
cap which is shown in Exhibit VII-4.   Designed  relatively simply,
wet caps usually consist of one or more inverted cones  surrounded
by a collection trough.   By directing a stream  of water over one
or more of the cones,  placed above the top  of the cupola, a water
curtain is formed through which cupola gases must pass and by
which heavier particles  of dust are removed from the gas stream.
          Water in a wet cap operation can  be applied in numerous
ways:   an open waterline can be centered above  the apex of the
                  A T KF«iRVFY ft rOMPIN'V  INT
                                                       VII  - 12

cone flow by gravity; a spray nozzle can be mounted  above  the
apex of the cone; sometimes clusters of the cone  arc arranged
horizontally and vertically; a ring of nozzles may be used;
water can be discharged from a hole in the cone apex and flow
downward by gravity; a continuous plate is also used whereby
water enters in sheets; with the cone hollow, water  can be
discharged from nozzles mounted at the periphery; and finally,
a small receivable water distributing head is sometimes mounted
above the main cone and water enters from an  adjustable slot at
the periphery of the small cone.
          2.  Dynamic Precipitator - This type is used to collect
light to heavy concentrations of  fine particles  such as found
in shakeouts and other sand-handling applications.   Essentially,
the dynamic precipitator is a combined exhaust  fan  and collector.
This design consists of a  prepackaged unit made  up  of an inlet
duct with a spray nozzle,  a multi-bladed  impeller and a special
housing that separates the cleaned air  from  the  dirty slurry.
          The basic cleaning  process consists of dirty gases
entering the inlet duct where  they are mixed  with water.
Specially designed blades  then  remove  particles  by capturing  the
dust on a moving film of water  on the  blade  surfaces.  The
force of the moving wetted blades provides  the  energy to wet  the
particles,  and  the centrifugal  force  discharges  and separates
the collected dust in  the  form of a  slurry  while exhausting  the
cleaned air.  An example  of  a wet dynamic precipitator is  shown
in  Exhibit  VII-5.
           Dynamic  precipitators must  be periodically inspected
to  assure  that  the fan  rotor and spray nozzles are not clogged.

                  A T KEARNEY &  COMPANY l»c

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                                                      VTT - 13

The rotor must also be checked  for  wear and buildup on blades.
This could cause an unbalanced  operation and  excessive loads on
fan bearings.
          3.   Centrifugal  -  Centrifugal wet collectors are  used
to remove dust from sand conditioning  equipment,  casting  lines
and cupolas.   The two basic  designs available in  this caccgorv
are the vane type and multiple  tube type.  The vane-type  collec-
tor consists of a vertical cylindrical housing and ono or marc
stationary vanes and impingement plates.  The tube type utilizes
a rectangular housing surrounding inlet collector tubes,  a  water
eliminator section and a clean  air section.   Both types utilize
simple water piping to produce  a film of water on the surface  of
the vanes.  Additional equipment includes pumps and/or piping
for vater circulation, a method of disposing  of sludge and  an
exhaust fan.
          With a vane-type centrifugal collector, dirty gases
enter the bottom of the main housing at a tangent which provides
the centrifugal force to impinge the larger  particles  against
the lower section of a shell.  The gases and  smaller  particles
flow upward through vanes  which produce a turbulent action.
Dust is removed by coming in contact with the wetted  impingement
plates and water droplets.  The gas then passes through  a. separa-
tor where the free moisture is removed.  An example  of a  vane-
type centrifugal collector is shown in Exhibit VII-6.
          In the operation of the tube-type centrifugal,  dust-
laden gases are led in tangentially at the upper end  of  the
collector and then move through multiple tube-type canals.
Centrifugal force hurls the dust particles against the wetted
peripheral surface of the unit.  The slurry is then separated
                            FY & COMP^VV l-ic
                                                    VII - 14

from the clean air by being forced down and out the bottom of
the collector.  The clean gases move parallel to Che water
stream towards the outlet at the lower end of the dust collector.
Exhibit V1I-7 illustrates a tube-type wet centrifugal collector.
          4.  Orifice - This collector type is used in sand
handling and cleaning processes.  Orifice units are rectangular
and employ one or more impeller orifices that are submerged in
water.  The clean air side of the main housing is equipped with
baffle plates to separate entrained moisture.  Orifice collectors
utilize the principle of centrifugal force and the mixing
action of dust-laden gases and water to achieve cleaning.
          The first step of the cleaning cycle consists of con-
taminated air entering the collector horizontally after which
ic is violently pulled down through water.  Fan suction con-
tinuously draws water and air up where it impinges against a
plate and sprays off.  This action causes great turbulence, which
in turn wets  the dust particles.  The gases are then  exhausted
out the collector after which a drag conveyor continuously
removes the settled sludge.  An orifice-type unit is  shown in
Exhibit VII-8.
          Water is continually reused and since a water curtain
is produced by airflow, no pumps and nozzles are required.
Furthermore,  orifice collectors normally do not require extensive
maintenance because the only moving device is an exhaust  fan.
In addition to fan maintenance, occasional inspection and clean-
                                                             4
ing of the impeller and moisture separator are also  required.
          An  important operating requirement of baffle-type
4
                                                                                                      A T KFMIVFY A COMPANY

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                                                      VII - 15

orifice collectors is  that  the water  level must be synchronized
with the amount of air flowing through  the unit if constant col-
lection and reasonable pressure  drop  are  to be maintained.
Recent orifice designs automatically  adjust operating water
                                     Q
levels when the exhaust volume varies.'
          5.  Centrifugal Spray  - This  unit is used on a wide
range of foundry applications from shakeouts  to cupolas.  The
centrifugal spray collector consists  of a cylindrical shell in
which are mounted a pump, spray  generator, and fan, all on  a
common shaft.  A separator is irounted on  the  upper section  of
the shell.
          Collection is achieved by combining high kinetic
energy water droplets with the contaminated gas.  Dirty gas
enters the unit and is directed  under a stationary impinger
where heavy particles are impacted and  carried off by  liquid
water.  After this, the air is drawn  up through a high velocity
water spray, where impingement of the smaller dust particles
takes place.  The cleaned gases  continue  upward through a moisture
separator and finally are exhausted from  the  unit.   Exhibit VII-9
illustrates a centrifugal spray wet collector.
          A variation of the design described above  is a  scrub-
bing  unit consisting of a cone bottom housing and a  pump  spray
generator device.  This unit is usually coupled with other  units
such  as  separate  exhausters, hot gas quenchers, moisture  elimina-
 tors,  etc.  to make a  cupola cleaning system.  The cone bottom
unit  operates on  the  same principle as the cylindrical shell
                                                        VII -  16

for the removal of airborne water which is handled  by the mois-
ture eliminators.
          These units utilize much of  their  input horsepower  to
create a high energy water spray.  This is different than other
wet-type units which overcome static pressure  drop  across the
collector.
          Centrifugal units require periodic inspection and ser-
vicing of pumps, spray generator cage, bearings, the main shaft
                4,
and drive motor.
          6.  Flooded Bed - The two basic types of  flooded bed
collectors are marble bed and impingement baffle grid.   Both
designs have common characteristics and also some differences.
Each employs a cylindrical shell with  a cone-shaped bottom
section, fixed blade moisture separators at  the top of the shell
and spray nozzles below the first stage of scrubbing.  Further-
more, both types operate on the principle of direct contact of
dirty gases with water spray in conjunction with venturi-designed
induced turbulence.  In a typical marble bed collector, gases
enter the collector near the bottom and then turn upward into a
water spray.  These water sprays are used to wet the lower
portion of the bed.  This causes the larger  dust particles to
separate and drop down.  The gases and water are then drawn
up by an exhaust fan through a bed of  glass  or other type balls
where smaller particles are captured by the  restricted flow.
The cleaned gases ascend further and move across moisture
separators and then out the collector.  The  dust-laden slurry
is drained down and into a sludge hopper.  An  example of a
                                                                                                   A T KF".RVFY

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                                                     VII - 17
marble bed collector is shown in Exhibit VII-10.
          Efficiency of this unit can be increased by  additional
layers of balls.  Spheres packed in contact with  each  other
constitute a multiplicity of Venturis to achieve  this  result.
          The impingement baffle grid collector uses one  to
three grids which consist of a perforated plate and impingement
plate above each perforation.  An essential difference of the
impingement baffle grid from the marble bed unit  is in the water
supply.  Each scrubber section of the grid type has an individual
water supply in addition to the water spray located in the cone
section.  Exhibit VII-U shows a grid-type flooded bed
          4
collector.
          7.  Venturi  - This unit is usually applied where heavy
concentration of both  coarse and extremely fine particles exists
and high efficiencies  on subraicron particles are desired.  In
a  typical cupola system, hot gases move from the  furnace to a
quencher where  they are cooled by a water spray.   Here, the
large particulate matter is removed.  From the quencher, gases
are directed to the venturi where they are accelerated to a high
velocity and brought into contact with multiple jet streams of
vater.  The water and  gases are  drawn through  the constricted
throat  of  the venturi  at such a  high velocity  that the water
atomizes into minute droplets and dust  particles collide with
the droplets and become  wetted.  This wetting  occurs  in the dif-
 fusion  area  downstream from the  venturi  throat.  The  dirty water
 is carried out  the  bottom and the gases  pass through  a moisture
                                                                                                                                     VII - 18
separator, are cooled and Chen exit through n saturated gas  stack.
A high pressure exhaust fan, piping and electrical controls  an-
part of the system.  Exhibit VI1-12 illustratcs n venturi
collector.
          Venturi scrubbers achieve a high efficiency by virtue
of a high pressure drop occurring across the venturi throat.
Some Venturis are designed with variable throats so that a more
uniform pressure drop can be maintained with variable gas flow.
          A variation of the venturi described above combines  a
marble flooded bed collector with a venturi section mounted  un-
derneath.  Nearly all of this system is encompassed in one large
chamber.  In the operation of a flooded bed venturi, dirty gases
enter the collector where they are met by a cooling water spray.
The gases then turn upward into the venturi and the large par-
ticles drop out of the airstream into a cone section.  Gases
and fine particles pass across the venturi and the particles
become wetted.  The marble bed and moisture eliminator act to
                                                                  4
further clean the gases and remove water drops from the effluent.
     (d)  Advantages of
          Wet Collectors
     Wet collectors can be applied to a variety of foundry  appli-
cations.  Certain designs, such as wet caps, require a relatively
low iiitial investment cost, limited space needs, no induced
draft fan and are rather simple to maintain.
     Venturi scrubbers have good collection efficiencies down
to particles of 0.1 or 0.2 microns in size but also have high
                                                        £,
energy requirements to achieve this cleaning capability.
                                                                                                A T KEARNEY & COMPANY  Isc

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                                                       VII -  19
     In addition, wet  collectors are capable of handling hot
gases, sticky dust  and high moisture content.  In some cases,
disposal of sludge  can be  achieved if foundries have slurry
pumps, settling ponds  or tanks, drag chain sludge removal
                                    1
conveyors or other  similar equipment.
     Finally, these system types are safer from fire hazards
than fabric filter  collector  designs.

     (e)  Disadvantages of
          Wee Collectors
     One major disadvantage is that operating costs can be high
for wet collectors  in relation to other  collectors due to water
usage, corrosion, and the  chemical  treatment needed for water.
Also, the high energy units,  such as Venturis, require a high
power usage.
     Another disadvantage  is  that since  the cleaned gas exiting
from the foundry is saturated with  moisture, a plume of condensed
steam develops which is visible until  the vapor trail evaporates
This condition can be mitigated through  the use of additional
de-misters.  Furthermore,  submicron dust sizes are difficult to
extract in dewatering equipment.  Acid pickup from burning coke
and oil from scrap also occur.
     If complete control of all solid  emissions is required at
a  later date,  it is often impractical  to make certain equipment
modifications  to wet collectors such as  use of aftercleaners.
However,  there have been instances  where medium energy systems
have  been  designed with the intent  of  making  future equipment

                 A  T *r»n^rv ft i- o M P s vs I •. r-
                                                                                                                                         VII - 20
modifications to increase cleaning capabilities.   Finally,  duo
to Che need for conservation of water, additional  equipment for
                                          2
circulation and clarification is required.

     (f)  Limitations of
     	Met Collectors
     Exhibit VII-13 indicates the smallest particle  that can
be collected by the seven types of wet collectors.   As  shown,
static washers are not capable of collecting dust  particles
under 10 microns in size and thus have the greatest  limitations
in this regard.  Conversely, venturi scrubbers, being able  to
collect particles as small as O.S microns in size, have the
                 4
least Limitation.
     Wet collectors are not applied for collection in certain
foundry areas such as boiler fly ash, pouring, mold  cooling
and pulverizing.  Also they are rarely used on woodworking  and
oil burn-off furnaces.
     Capacity ranges available for the different types  of
                                                4
vet collectors are also shown in Exhibit VII-13.

     Wet collectors have no practical limitation regarding
temperature or moisture conditions that may exist  during opera-
tion.6
Fabric Filters
     (a)  Historical
     	Background
     Until the mid-1930's, foundry fabric collectors consisted
                 A T KEMI^FY & COMP"lVY

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                                                    VII -  21

of large U-shaped frames,  originally of wood,  Co which  a cotton
cloth or canvas was cacked or otherwise attached to both sides
of the structure.  Panels  were installed vertically with the
top sealed to an adjacent  header so dust-laden air was  forced
through the fabric with the cleaned air gathered in the inside
of the support structure and exhausted through the open top.
Periodically, the collector was stopped and  the accumulated dust
load dislodged by vibration.
     During the early 1930's, design improvements were  intro-
duced tc provide more effective vibration of the filter cloth,
more positive seals between fabric and support, and faster  media
replacement.  It was during this period that Che current concepts
of the envelope and cloth  tube types were developed.  Sectional-
ized, continuously operated collectors were  a  logical refinement
for larger foundry applications where the collector could not
be stopped with the frequency needed to maintain the desired ex-
haust flow.
     It was the pressure on the industry by  the Los Angeles Air
Pollution District that generated the use of glass fabric for
cupola gas cleaning during the late 1940's and early 1950's.
Typical early installations consisted of relatively crude de-
signs where long tubes were suspended from a mechanism  that was
manually operated to "rock" the cubes during shutdown.  Produc-
tion of glass cloth with a silicone lubricant  permitted this
mild flexing action without rupture of the glass fibers.  The
                A T h r » n v r v
                                <-OM p \ \ v
                                                         VII  -  22

sensitivity of glass fabric to flexing encouraged  the  develop-
ment of collectors of the reverse flow concept  to  provide  more
effective collected dust removal and continuous operation  of
uie collector.

     Fabric filters for electric arc furnaces in the gray  and
malleable iron foundry use exhaust control methods and generally
orlon or dacron fabric based on practices developed in steel
foundries.  Local exhaust hood concepts date back  to development
work by the farm implement industry foundries in the mid-1940's.
While medium pressure loss wet scrubbers were used on  early in-
stallations, they gave way to the higher efficiency of the fabric
                                                                   c
filter by the mid-1950's for electric arc furnace  fume collection.*
     (b)  General Characteristics
     	of Equipment	
     The basic principle of fabric collection  consists  of dust-
laden air passing through a filter media.  The media  acts as a
base to build a mat of the collected material  on  the  dirty air
side.  As the dust builds up on the fabric, resistance  to airflow
increases.  Periodically, the airflow must be  stopped and the
accumulated cake removed.  This can be done by vibrating the bag
and letting the dislodged material fall into a hopper.   It can
also be accomplished by using reverse or secondary  airflows.
     Fabric filters are quite versatile in their  contaminant
removal capabilities.  Since particles as small as  0.2  microns
in size can be captured,  excellent collection  efficiencies can
be achieved.  Furthermore, dust concentrations can  be heavy
                                                                                                   A  T KFMJVEY A roMP^VV T-

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                                                       VII - 23

or light and capacity ranges can also vary with minimum effect
on efficiency.

     A significant factor regarding operation of fabric filters
is the ratio of cubic feet per minute of  air handled in the  sys-
tem to the square feet of cloth area of the collector.  This  is
usually referred to as the air to cloth ratio.  By lowering  the
ratio, less air velocity through the fabric is achieved, and
bag wear decreases.  However, economic factors also need to be
                                    4
considered in determining the ratio.
     The filter cloth is usually a specially woven cotton.  How-
ever, dacron or orlon is used for temperatures reaching 225°  F,
and glass for 550° F temperatures.   The units must be operated
above the dew point temperature of the airstream so that moisture
does not form to produce a mud cake to hamper air passage  through
the media.1' *' 5
     Two basic types of cloth filters are available—the flat-
or envelope-type bag and the tubular-type bag.  The flat- or
envelope-type bag generally provides  a more compact filter and
better cleaning because the flat bag  is kept taut.  Dust is
collected on the outside surface of flat bags.  They also require
a rigid framework so that collapse  of the bag can be prevented.
Exhibit VII-14 illustrates a flat-type bag used on a fabric
filter.
     The tube- or stocking-type bag is suspended from the shaker
mechanism at the top and fastened on  the bottom.   Dust is
               A  T KEARNEY & COMPANY
                                                                                                                                             VII  - 24
captured on the inside of the  tube.'
tube unit.
Exhibit VII-15 shows  a
     The key to successful operation  and  continued efficiency
of fabric collectors  is  planned maintenance.   Bags need to be
inspected for leaks and  cleaned.   Shaker  mechanisms and baffle
plates have to be checked for  proper  cleaning action and wear.
The valves and fan also  require inspection to determine if they
are functioning properly.

     The results of numerous investigations  performed on dust
separation processes with fabric  filters  can be summarized as
follows:
          - With increasing temperature,  the  collection
            efficiency drops and the  filter  resistance
            increases.
          - The separation of particles larger  than 0.5
            microns takes place through an impingement
            and a sieving effect.   Particles  smaller than
            0.5 microns are separated mainly  by diffusion
            and electrostatic forces.
          - The separation of particles takes place mainly
            on the outer surface of the filter  fabric.
            The filter resiseance naturally  increases with
            thicker filter fabric, but the collection
            efficiency does not improve in the  same propor-
            tion.
          - The smaller the diameter  of the  fibers,  the
            smaller the particles which can be  separated.
            Stronger fibers have to be incorporated into
            technical filter fabrics  for  strength.
          - The filter resistance of  fabrics  is directly
            proportional to the air or gas throughput.2

     (c)  Description of
          Specific Types
     Three types of fabric filters used are:  intermittent, con-
tinuous automatic, and reverse jet continuous.  The basic
                 A T K J- "iRVE Y  & COMP^S•Y l^r

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                                                     VII  -  25

principle of fabric collection previously  described applies,
in general, to each of the three systems except  for bag clean-
ing.
          1.  Intermittent - This unit  type  lends  itself to
collection of widely scattered dust of  an  intermittent nature
where the entire system can be shut down periodically to be
cleaned.  This type of collector can be used on  any system that
can be interrupted or bypassed during the  cleaning cycle.
Either the fabric filter, vibrating mechanism and  exhaust  fan
arc packaged in one unit or the exhaust is separate.
          The intermittent-type collectors in the  smaller  sizes
often are factory assembled, eliminating the need  for field
erection.  Larger fabric collectors are available  that contain
up to 12,000 square feet of cloth area. Field erection of these
                                «i 5
units is required in many cases.
          Exhibit VII-16 shows an example  of an  intermittent
collector.
          2.  Continuous Automatic - With  a  continuous automatic-
type collector, one section of the collection system can be  shut
down and remaining sections will continue  to operate.  The
system consists of multiple collection sections, usually not
less than four or six, each of which can be  programmed to  clean
for a desired time period, progressing through the entire  collec-
tor automatically.  High concentrations of dust  can normally be
handled and a fairly uniform pressure drop is achieved with  this
type of unit. '
r n M i* \ v ^
                                                                                                         VII - 26

                                                             Some reverse flow designs rely on flexing during
                                                   collapse and reinflation to dislodge collected dust without
                                                   mechanical vibration.   In these designs, the reverse flow of
                                                   air through the bag has to be carefully controlled or it could
                                                   damage the bags.  A sudden full reinflation of Che collapsed
                                                   bag could result in bag failures at the points where severe
                                                   fiber flexing occurs such as along the edge of a seam.  One manu-
                                                   facturer handles this  problem by gradually introducing the flow
                                                   of reverse air.  Then, the reverse air valve is kept open tempo-
                                                   rarily when the filtering process begins, to allow a gradual
                                                   buildup of pressure.  Once the proper pressure is restored, the
                                                                               5, 10
                                                   reverse air valve is closed.
                                                             Continuous automatic-type systems require additional
                                                   equipment such as spare sections, damper assemblies, multiple
                                                   shaker units and field assemblies.
                                                             Also, the damper and shaker units require additional
                                                   maintenance.   An example of a continuous automatic system is
                                                   shown in Exhibit VII-17.
                                                             3.  Reverse  Jet Continuous - Reverse jet continuous
                                                   units are used where a high concentration of fine particles
                                                   is being collected or  where the material must be continually
                                                   collected.   This unit  utilizes a. secondary source of air to dis-
                                                   lodge the dust cake.  As  the dust particles accumulate,  airflow
                                                   resistance through the filter increases.  At a predetermined
                                                   resistance level,  a high  velocity air jet penetrates the filter
                                                   tube  through a blow ring  moving along the tube.   This air jet,
                                                   combined with the  flexing action of the filter tube, dislodges

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                                                    VII  - 27

                                                             1, «
the accumulated dust  which is  then carried down into a hopper.
          Secondary air is provided  through use of an attached
blower.  One manufacturer's design utilizes an externally located
pressure blower that  is connected to the main collecting unit
by a flexible heavy-duty,  industrial-type hose.  With the pres-
sure blower, various  types of  air intake filters are used to
control incoming air.  Environmental dust conditions and  the
specific maintenance  requirements of the system are two factors
determining the type  of air intake filter to use.
          The advantage of this system  is that cleaning is
usually more efficient than shaking. Also, less cloth area per
cubic foot per minute is required compared to other fabric-type
collectors.  Operating costs and maintenance expenses are
                                                    1» 4
reportedly higher than shaker-type fabric collectors.
          Exhibit VII-18 illustrates a  reverse jet continuous
fabric collector.
     (d)  Advantates of
          Fabric Filters
     Well-designed fabric filter installations  provide excellent
collection efficiency on dust particles  down  to 0.2 microns  in
size and can be designed to handle large gas  volumes.  In
addition, dispersion of exit gases into  the atmosphere does  not
present a steam plume problem.
     Fabric filters normally operate with a low pressure drop,
three-inch to five-inch, and, therefore, have low power require-
ments.  Fabric units are not normally subject to  corrosion,
                A T KEARVEY & COMPANY lie
                                                      VIT  - 28

                                                         L, 4
and furthermore, no disposal of waste water is  required.

     (e)  Disadvantages of
          Fabric Filters
     Initial equipment and erection cost can  be high and  large-
space requirements are usually necessary.  Filter  bags  need
periodic replacement, adding to the maintenance costs.  Added
safety precautions are sometimes necessary for  cleaning in-
flammable gases.  Furthermore, there is the danger of tempera-
tures sinking below the dew point as a result of evaporative
cooling which would cause moisture to form and  clog filters.
Carry-over of glowing particulate matter represents a danger
to natural or synthetic fiber bags.
     Dry material disposal can be a problem as  particle sizes
of collected material decrease.  Refuse handling and secondary
dust dispersion are factors that must be considered in this
      . 1. 2, 4
regard.
      (f)  Limitations of
     	Fabric Filters
     In a normal installation, the smallest particle size that
can be effectively captured by a fabric  filter  collector is
approximately 0.2 microns in size.  Special equipment modifi-
                                                4
cations could result in increased efficiencies.
     There are  temperature  limitations  that must be maintained
with respect to different fabrics as shown  on the  following
      49
page.

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                                                   VII  - 29
    Fabric
    Cotton
    Wool
    Nylon
    Dacron
    Nomex
    Orion
    Creslan
    Dynel
    Poly-
       propylene
    Teflon
     Fiber glass
     Filcron
Melting Temperature
Decomposes at 302° F
Chars at 572° F
      480° F
      482° F
Decomposes at 700  F
              o
Softens at 482  F
              o
Softens at 475  F
Softens at 325° F
      333° F
                 o
Decomposes at 750  F
Emits toxic gas at
  4 SO0  F
         o
     1,470
Softens at 505° F
      Recommended
  Maximum Continuous
Operating Temperature
        180° F
        200° F
        200° F
        275° F
        350° F
        260° F
        250° F
        160° F
        200° F
        400° F
        550° F
        270° F
     Fabric  filters are  not  applied  for collection in certain
foundry areas such as  boiler fly  ash,  pulverizing and oil burn-
off furnaces, nor are  they suitable  for handling emissions from
oily scrap and phenols from shell molds and cores.
     Pertaining to capacity ranges,  small  intermittent fabric
collectors are designed  to handle from 300 to  2,000 cubic feet
per minute.   Capacity  rates can be  varied  quite widely for large
intermittent, continuous automatic  and reverse jet continuous-
type fabric collectors.
                A T kFM»V|-Y & rOMPAVY
                                                                                                                                         VII - 30
     Fabric materials have certain limitations that appear note-
worthy.  Wool is not suitable when dirty gases contain  tar or
have an acidic effect.  Glass fabrics are  less flexible than wool
and cannot withstand strong mechanical  stresses.   Finally, glass
is not suitable  for handling  fluoride compounds  since the lubri-
cants  and  fibers are subject  to  chemical  attack.

Electrostatic
   Precipitators
      (a)   Historical
     _ Background
     The  first  effective  electrostatic  precipitator was designed
 in 1883  for cleaning top  gases  from a blast furnace.   Since
 production of direct voltage through friction was unsatisfactory,
 further application was not attempted at that time.  In  1906,
 an electrostatic precipitator was introduced that used a
 mechanical high voltage rectifier.  In 1916, a dry-type
 itator was designed followed by wet systems shortly  thereafter.
      The  electrostatic precipitator for  cupola gas  cleaning has
 been more widely accepted  in Europe than in  the  United States
 where the trend in recent  years has been strongly in favor  of
 high  energy wet scrubbers.  Only two precipitator installations
  in foundries have been reported in this country in  the  last  two
  years-one in Texas and the most recent in Indiana.
       (b)  General Characteristics
       _ of Equipment __
       This type of collector utilizes high voltage,  low amperage
  direct current for operation.   A complete system usually consists
                                                                                                     A T KEARSFY & COMPANY  \-.<~

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                                                     VII  - 31
of the following:   precipitator housing,  discharge electrode,
collecting electrodes, gas distribution system, cleansing de-
vices, dust and sludge removal and electric power supply facili-
ties.  Wires or rods are suspended from an overhead high voltage-
charged grid between grounded plates.  These wires are hung on
approximately 2- to 3-foot centers and carry 50,000 to 100,000
volts.  When the voltage reaches the corona stage, the gases
passing through are ionized, forming negative  and positive ions.
With the wires negative and the plates positive, the  negative
ions travel across to the positive collecting  plates  and in the
process negatively charge the dust particles which also then are
attracted to the positive plates.   Removal of  dust particles
varies depending on whether the unit is a wet- or dry-type pre-
cipitator.
     Performance of electrostatic  precipitators essentially de-
pends on the characteristics and relationship of the  suspended
particles, velocity of the gas passing through the collector
and electrical resistivity of the  material deposited  on the elec-
trodes.
     Pertaining to the suspended particles, it is important to
know their size, amount of particles in suspension and chemical
analysis.  Particle size will have a bearing on whether primary
collection preceding the precipitator is  required.  The amount
of particles in suspension has an effect  on design efficiency
required to meet emission codes.  Chemical composition relates
to particle size since some nonferrous metals  product fine par-
ticles.
                 * T K F M» V F Y (* f n w «" S VY !>»•
                                                                                                                                           VII  -  32
      The  velocity of the gas passing through the collector is
determined  by  the length of time the particulate matter must
remain  in an electrical  field.   This period determines the
number  and  size  of collection tubes needed to treat the total
volume  of gas  at this  velocity.

      Electrical  resistivity pertains to the measurement of the
ability of  a particle  to resist  an electrical unipolar charge.
This  measurement indicates  the amount  of conditioning necessary
and the length of time a particle  needs to remain under the
influence of the electrical  field.   Resistivity varies over a
wide  range  depending on  the  temperature and moisture content
of the gases.1'  2' *

      (c)  Description of
     	Specific Types
      Electrostatic precipitators can be either  wet- or dry-
type  collectors:
          1.  Wet Type - These units usually consist of a  cir-
cular shell or casing that is divided  into two  gas  compartments
by a header plate.  Suspended from the header plate are a  number
of tubes that form gas ducts.  Discharge electrodes are suspended
in the tubes from an insulated framework.   Dirty gases pass from
the lower compartment through the  tubes for  cleaning and  then
into the upper compartment.  Dust  particles  are  then removed  from
the surface of the collecting pipes  by water flushing.
          The discharge  electrodes  are energized by electrical
equipment consisting of  a manual or  automatic control  unit,
high voltage transformer and rectifying equipment.   Control

                 A T  KEARVEY & COMPtVY l^<-

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                                                     VTI  -  33

equipment is usually all electronic.   Power  level or  sparking
rates act as electrical feedback signals  that  activate  the
control equipment.  With this type  of equipment  system, electri-
cal input under varying process conditions such  as  temperatures,
flow rates, dust particle size and  resistivity is optimized.
Rectifying equipment can be either  mechanical, motor  driven,
electronic or solid state.
          Wet-type units are frequently built  vertically.
In this arrangement, gas flows through the filter in  a  vertical
direction and normal1;, from bottom  to top.   This results  in a
longer period of stay for dust particles  in  the  collector be-
cause of the gravitational force and produces  better  separation
                    1  2  A
of coarse particles. '  '
          Exhibit VII-19 indicates  a wet-type  electrostatic
precipitator gas cleaning system.
          2.  Dry Type - The basic  structure of  these units con-
sists primarily of a rectangular shell or casing from which are
suspended a number of collecting electrode plates.   These plates
are  parallel to each other and equally spaced to form channels
through which gases pass.  High tension discharge  electrodes are
suspended vertically in the center of the channels.  Collected
material is removed from  the surface of the collecting electrodes
by a continuous rapping device.
          Dry process electrostatic precipitators  are usually
built on a  horizontal basis.  A horizontal arrangement allows the
gas  to move in  this direction which  facilitates the cleaning o£
                 A T h r MI ** E Y & f O M P \ V ^
                                                       VII  -  34

collecting electrodes by means of rapping or shaking.  Dust docs
not fall against the gas stream but only at right angles to it.
          The rapping mechanism usually consists of a number of
hammers that are driven pneumatically or by means of impact
shafts striking against the electrodes in regular intervals.
The electrodes can also be deflected horizontally out of their
normal position over a cam shaft and then made to strike against
an anvil.  The discharge electrodes are rapped with hammers
that are lifted by tie rods and then released.  Regular mainte-
nance is necessary for the electrode rapping equipment.
          The collecting electrodes should represent a freely
oscillating system with a minimum damping capacity.  This  allows
a uniform distribution of the oscillations over the  plate  sur-
face, so that particles of all sizes can be removed  from the
                          124
electrodes during rapping.  '   '
          A dry-type electrostatic precipitator gas  cleaning
system is illustrated in Exhibit VII-20.
      (d)  Advantages of
          Electrostatic
     	Precipitators
     These unit types provide  excellent removal of  solid
particles when the collector  is properly designed  to enable such
performance.  Power  requirements are substantially  less  for
electrostatic precipitator units than  for other induced  draft
collection systems.
      Furthermore, these collector types can be  designed  to
handle moisture, oil and similar conditions that are unsuitable
                                                                                               A T KEARVEY 8. COMPANY Ivr

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                                                    VII  -  35

for certain other collector designs.  Finally, these units  are
flexible in that additional cells  can be  added to existing
equipment to meet changing process requirements or more
                124
demanding codes. '  '
     (e)  Disadvantages of
          Electrostatic
     	Precipitators
     For small gas volumes—50,000 CFM or less—costs are dis-
proportionately high on a per CFM  basis because of power equip-
ment and engineering cost requirements if the unit is not an
"off che shelf" design.  Maintenance expense Is greater than units
having a lower order of collection.
     Gas temperatures  and water  vapor content need to be closely
controlled due to the  resistivity  characteristic of particles.
Fluctuations of cupola stack temperature  can make it difficult
to maintain proper temperature of  gases going to the collector.
     If the effluent emitting from the cupola contains iron and
silicon oxide and the  collector  is operating at temperatures of
300° F or above, problem' could  develop.   At these temperatures,
the resistivity oE silica will increase to the point where  it
is necessary to condition the gases, by adding moisture.  This
moist condition will accommodate silica,  but the iron oxides
will tend to coagulate on the collector plate and be difficult
Co remove.
     Other disadvantages are chat  a precleaner is sometimes
necessary for heavy loads and a  dry dust  disposal problem may
                                                                                                                                VII  - 3f>
develop.  Finally, there is a potential risk  involved  with
using high voltage equipment. '   *   '    '
      (f)  Limitations of
          Electrostatic
     	Preeipitators
     The smallest  particle that can  be collected with a normal
electrostatic precipitator installation  is  0.1  microns in size.
Increased efficiencies are possible  through equipment modifi-
cations .
     These collectors are  limited  in their  application to
different' foundry  processes and consequently  have been very
rarely  used.  Furthermore, these units should not normally be
                                                o   1, 2,  4
used when temperatures exceed  approximately 700  F.

Collection Efficiency
  of Emission Control
  Equipment  Systems
     The success of  a control  equipment  system  will depend upon
its ability  to  remove sufficient emissions  to provide an
acceptable order of  cleanliness.   Criteria  for  evaluating
collection efficiency will be  determined by the objective of
the system and  often by  regulations  defining  acceptable emis-
sion levels.
     Accurately defining equipment efficiency is difficult
since  inlet  loadings vary  widely in  concentration, particle size
ranges  and dust composition  for most foundry  operations.   This
occurs  not only between  similar operations  in different plants,
but also with any  given  application, almost minute by minute
                                                                                          A T KF \nvrv ft

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                                                     VII  -  37

during a normal working day.   Consequently,  designers of control
equipment find it difficult to define exit or  cleaned gas  con-
ditions other than as a function of incoming particulates.   The
lower the order of collector performance,  the  more  difficult
it will be to predict exit conditions except in  terms of over-
all percentage of removal or percentage removed  by  particle
size fraction.
     Yardsticks used to express collection efficiency of
emission control equipment include-  (a) weight, (b) particle
size count, (c) opacity and (d) ground level concentration.

     (a)  Height
     The most acceptable yardstick for expressing collection
performance is on the basis of the weight of emissions  collected.
Different scales are used  in this regard including pounds  per
hour, pounds  per unit of process weight (tons  melted,  and
sand conditioned), pounds  per  1,000 pounds of  gas and  grains
per standard  cubic foot of gas.
     Regarding the grains  per  standard cubic foot of gas  scale,
performance Is calculated  on the basis of the  ratio of weight
of particulate per unit of gas entering the collector to the
weight  of particulate per  unit of gas  trapped in the collector.
This ratio is then expressed as a  percentage.   An example of
how efficiency is calculated in this manner is given in the
tabulation shown on  the  following  page.
                  A T Kr»BVrV 5.
                                                      VII  -  38

          Dust entering collector  -- 1.0 grain/cubic foot
          Dust leaving collector   -- O.I grains/cubic foot
          Dust trapped in collector-- 0.9 grains/cubic Coot
Thus, 0.9 grains/cubic foot divided by 1.0 grain/cubic foot  =
                              4
90% dust collector efficiency.
     Exhibit VII-21 indicates relative efficiencies of collector
systems based on outlet loadings in grains per cubic  foot  of
gas for various foundry applications.  These are  typical per-
formances that can vary based on differences in melt  charge,
dust characteristics, particle size distribution,  collector
design and numerous other factors.   By referring to  the figures
on Exhibit VII-21, collectors can be ranked according to effi-
ciency as shown on the following tabulation.
        Type  Collector               Collection Efficiency
        Fabric Filter                        Highest
        30"-70" wet scrubber and
        electrostatic  precipitator
        6"-30" wet scrubber
        Low  efficiency cyclone
        Wet  cap                             Lowest
      These  efficiency rankings  are general,  overall indications
 that are not related  to  costs,  collector design,  specific appli-
 cations or  other factors.   They  are simply an indication of the
 relative performance  that  has been experienced with these sys-
 tems.
                                                                                                   A T KFARWEY St COMPANY Ivr

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                                                   VII  - 39

     (b)  Particle
     	Size Count
     A count of particle sizes collected  is  another method wide-
ly used to express efficiency of collection  equipment.   This
requires knowing the fractional efficiency of a collector at
various micron size ranges and also the particle size distribu-
tion.
     Particle size efficiency curves are  available for most
commercial collector designs, although any such base curve
must be modified for the influence of particulate concentration,
particle shape, specific gravity, chemical characteristics and
various other factors to fit a specific situation.  Where inlet
conditions cannot be accurately specified because of variable
composition and rate of contaminant release, new processes not
yet in operation, or high cost of data development, specifica-
tion of collector performance on a fractional basis is usual.

     A convenient way of comparing relative  performance  of
various collectors by this method is to determine overall col-
lection efficiency based on a standard test  dust.  This  was
accomplished by 1956 and the test results are presented  in the
following paragraphs.
     The test was conducted on a silica powder which has a grad-
ing about the same as typical fly ash from a pulverized  fuel
boiler.  The grading of this dust is shown in Exhibit VII-22.
As shown in the exhibit, the largest percentages of dust were
in the 20- to 75-micron size ranges and also under 2.5 microns.
                                                      VII - 40

     Based on this standard dust,  collection efficiency was then
calculated for various collectors,  the  results of which appear
in Exhibit VII-23.
     The efficiencies shown at  five microns  were taken from
grade efficiency curves developed  for each collector.     A
ranking of overall collector efficiency based on these results
is shown in the following  tabulation.
         Type Collector               Collection Efficiency
         Fabric filter                       Highest
         Venturi scrubber
         Wet impingement scrubber
         Electrostatic Precipitator
         Spray tower
         Self-induced spray deduster
         High efficiency cyclone
         Medium efficiency cyclone           Lowest

     As discussed previously, these figures  serve to place  the
collectors in order of merit in terms of collection efficiency
only.  A more meaningful assessment includes consideration  of
costs and other relevant factors.

     (c)  Opacity
     Opacity, or discharge appearance from a stack, is  another
yardstick often used to measure collection efficiency of  control
equipment.   The Ringelmann Scale shown  in  Exhibit VI-1  is one
of the most commonly used measures  of this type.
                                                                                                 A T KFM»VFV

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                                                     VII -
     A major limitation of opacity measures, which were discussed
in Section VI,  is that discharge appearance  from a stack will
seldom indicate the degree of collection.  For example, where
only coarse particles are released,  such  as  snag and portable
grinding, there would be no visible  escapement if exhausted dust
were discharged to the atmosphere without collection equipment.
On the other hand, removal of 90% of the  metallic oxides
generated by the electric arc furnace could  make little or no
reduction in the visible plume.
     Because acceptable discharge appearance for most  foundry
processes occurs where solid concentrations  do not  exceed  0.05
grains per cubic foot of gas, this weight measure  is often sub-
stituted  for performance in terms of equivalent opacity.

      (d)  Ground Level
          Concentration
     The  objective of air pollution and public  nuisance
legislation is,  in part, one of controlling the  air quality  at
ground level.  However, measured in terms of tons  per  square
mile, micrograrss per cubic meter, or as a soiling index,  it  can
only indirectly  be related to the condition of a  discharged
quantity  of process  air because of diffusion, turbulence,  wind
velocity  and direction, and contributions from other sources.

Factors  Affecting
   Control Equipment
   Collection Efficiency
      A number  of operating conditions and other factors affect
gas  cleaning performance.  Certain  of these have more effect
                   T i\r » n vr v
                                                     VII  - 42

on efficiency than others while some conditions are difficult
to evaluate because of limited factual knowledge on their
influence.  Furthermore, some conditions appear to affect all
control systems while others affect only one or a few systems.
          1.  Melting Operations - The cupola melting operation
results in exhausting large volumes of high temperature gas
laden with dust particles and fume.  It is difficult to arrive
at valid generalizations on how melting operations affect
collection efficiency as evidenced from the following statements-
              It would be helpful  to the average
              foundryman if an average emission
              load  from the cupola melting opera-
              tion  could be established.  This
              is impossible, however, due to  the
              varied operations  from one foundry
              to another, and due  to the complex
              melting cycle, metal composition
              and operations of  various  foundries....
              The volumes of gas  exhausted  and the
              quantities of coarse and  fine materials
              making up  the total  emission  vary in
              cupola operations  depending on  melting
              rate, charging methods and cleanliness
              of materials.  "
          This  conclusion was also reached  in an  analysis of
cupola  furnace  metallurgy.  It was found  that values for  coke
rate, blast  volume, and blast temperature generally  applied in
practice  result in  such widely varying melting  conditions,  that
a  universally valid statement on the effect of  chemical con-
stituents in charge materials on the characteristics of the
reaction  products,  namely gas dust, cannot  be made.
          This  problem  is further  exemplied  from  the following
findings:
              The raw gas contents ascertained  during
              the...survey did not show  any relationship
                                                                                                        A T KFM»VFY ft rOMPVVS

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                                                     VII  - 43
              between dust concent  on  Che  one hand and
              coke race and specific melting race on the
              other....  The dust content  of the waste
              gas from basic hot blast cupolas was es-
              pecially high on account of  the large
              proportion of small-sized  steel scrap
              material in the burden.  If  one calculates
              the corresponding dust emission per ton
              of iron from the top  gas dust contents,
              there appears to be an increase with in-
              creasing coke rate....   Because of uncer-
              tainties in the calculation  of top gas
              and waste gas quantities per ton of iron
              in each case, many of these  values are not
              very reliable.2
          It can be established chat one of the factors affect-
ing collector efficiency is the raw gas  dust content.  Further-
more, it has been shown that data are  incomplete on the effect
of melting operations on dust content, except for the general-
ization that dust content is influenced.   Therefore, ic can be
concluded that melting operations affect collector efficiency,
but the exact degree of influence is unknown at this time.
          2.  Gas Flow Rate - Gas flow rate variations result
in velocity changes and thereby influence  control equipment
efficiency and pressure drop.  The  influence on efficiency
varies with the control system being considered.
          With dry centrifugal cyclones, the degree of particle
collection is proportional to the amount of centrifugal force
exerted on dust particles in a waste gas stream.  In conical
portions of a cyclone, centrifugal  force,  and thereby collection
efficiency, is greatest at high gas velocity and with a small
cyclone diameter.  However, there are  limitations to this appli-
cation.  In a cyclone operation, there is  an inlet velocity
beyond which turbulence increases more rapidly than particle
migration to the wall.  When such conditions are reached, with
                A T KFMJVFY « ^OVP^S-Y l^r
                                                                                                                                       VTT -
further increases in flow rate, collection  efficiency actually
          16
decreases.
          Pertaining to wet collectors,  the following statement
indicates the effect of gas flow on efficiency.
              The faster the particle  is  traveling,
              the less likely it is to avoid colli-
              sion.  Therefore, the efficiency  in
              scrubbers is a function  of  the velocity
              in the collection area,  which in  turn
              is related to the overall  pressure  drop.
              So, high energy scrubbers  in  general are
              more efficient than low  energy scrubbers.1-
                                       • *
          In the operation of fabric filters, Che velocicy at
which the gas passes through the fabric must be low.  "This is
because higher velocities lead to compaction of the dust  cake,
which results in high pressure drop, or worse,  in breakdown of
the filter bed, allowing coarse parcicles to pass.  Therefore,
to enable normal bag filters to operate  at  high efficiency, it
is necessary to provide large areas for  filtration and avoid
frequent cleaning.  The reverse jet filter  overcomes  this
limitation to a great extent by removing  deposited dust by a
reverse current of air.  Thus, the buildup  of dust is avoided
                                                  14
which eases the limitation on operating  velocity.
          Fabric filters are adaptable to gas rate variations
because a barrier for particulate removal is developed.  How-
ever, these systems are subject to pressure drop  variations
and generally speaking, the cleaning system will  not  deliver at
a constant rate when the pressure drop increases.
          Gas flow rates affect electrostatic precipitator
performance in that the higher the migration velocity of  the gas,
                                                                                                    T >• r < n v r v
                                                                                                                 r- n M p v vv ' • r

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                                                     VII - 45



the larger the Increase in collection efficiency.   Further

factors must be considered in this regard,  though,  including:

                 Surface area.

                 Particle composition and chemical  analysis
                 of dust.

              -  Characteristic curve of current and voltage.

                 Flashover frequency.

              -  Velocity and pressure in precipitator.

                 Gas composition,  temperature  and moisture.

                 Dust resistance.

          Finally, optimum gas flow velocities have not generally

been established with certainty for any of  the control processes

because they are greatly influenced by properties of dust and

carrier gas as well as by the design of the collection equipment.

          3.  Carrier Gas Temperature - Gas temperature has a

principal influence on the volume  of carrier gas.   This, in turn,

influences the size and cost of the collector  and the concentra-

tion of the contaminant per unit of volume.  Furthermore:

              In electrostatic precipitation,  both  dust
              resistivity and the  dielectric strength
              of the gas are temperature dependent.

              Wet process cannot be used at temperatures
              where the liquid would either freeze, boil,
              or evaporate too rapidly.  Filter media can
              be used only in the  temperature  range within
              which they are stable.  The structure must be
              of materials that retain their integrity at
              their operating temperatures.

              Last, low temperature gases from a stack
              following control equipment disperse  in the
              atmosphere less effectively than high tempera-
              ture gases.  Consequently, benefits derived
              from partial cleaning accompanied by  cooling
17
                A T KEARNEY & COMPANY I
                                                      VTI - 46


                 may be offset if the cool  stack  gas  cannot  be
                 well dispersed.  This  is a factor  of impor-
                 tance in wet cleaning  processes  for  hot  gases,
                 where the advantage gained by  cleaning  is
                 sometimes offset near  the  plant  by downwash
                 from the stack because the stack gas is
                 cooled. 17

          4.  Carrier Gas Pressure - Pressure of  the  carrier

gas is not of prime importance in particuLate collection  ex-

cept for its effect on gas density, viscosity,  and  electrical

properties.  It could be a factor, however,  in  deciding whether

a high energy wet scrubber or another type  of control system is

best suited for a particular application.   An available source

pressure can be used to overcome the high pressure  drop across

the scrubber, reducing the high power requirements  that could

limit the use of scrubbers.

          5.  Carrier Gas Viscosity - This  gas  property has  an

effect on efficiency as shown below:

              Viscosity is of importance to collection
              techniques in two respects.   First, it
              is important to the removal mechanisms
              in many situations  (inercial  collection,
              gravity collection, and electrostatic
              precipitation).  Particulate  removal
              techniques often involve  migration  of the
              particles through the gas stream  under
              the influence of some removal force.  Ease
              of migration decreases with increase  in viscosity
              of the gas stream.  Second, viscosity in-
              fluences the pressure drop across the col-
              lector and thereby becomes a  power  con-
              sideration.17

          6.  Carrier Gas Humidity - Gas humidity affects the

performance of control systems as evidenced in  these  statements:

              High humidity may contribute  to accumula-
              tions of solids and lead  to the caking  and
              blocking of inertial collectors as  well as

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                                                     VII - 47
                  caking on  a filter medium.  It can also re-
                  sult  in  cold spoc condensation and aggrava-
                  tion  of  corrosion problems.  In addition,
                  the presence of water vapor may influence
                  the basic  mechanism of removal in electro-
                  static precipitation and greatly influence
                  resistivity.  In catalytic combustion, it
                  may be an  important consideration in the
                  heat  balance that must be maintained.  Even
                  in filtration, ic may influence agglomeration
                  and produce subtle effects.!'
          7.  Electrical Properties of Carrier Gas  -  This  is  a
 factor regarding electrostatic  precipicators because  the rate
 or ease of ionization influences  particle  removal.  The in-
 tensity of Brovnian motion, which states  that particles in motion
 in the neighborhood of the collecting  droplets  diffuse to  them
 and are intercepted, and gas viscosity, both increase  with gas
 temperature.  These factors are  important  characteristics  that
 relate to the sonic properties of the  gas  stream.   Increase in
 either property will tend  to increase  the  effectiveness with
 which sonic energy can  be  used to produce  particle  agglomeration.
          8.  Dust Composition -  An analysis  of cupola dust
 composition from different foundries is tabulated in Exhibit
 VII-2A.  As indicated by these results, dust  composition varies
 quite widely.  This is  important  with  respect to collector
 efficiency since dust constituents  with higher specific weights
will sink down easily in air as a  result of mass forces.  Also,
 the carbon content of dust makes  wetting more difficult and thus
                                          2
 puts higher requirements on wet scrubbers.
          9.  Dust Loading - Dust  loading  will influence differ-
ent types of collectors in different ways.  For example, cyclone
efficiency will  increase at  higher  dust loadings, but  extremely
17
                                                                                                                                        VII  -  48
high loading may overtax  the  rapping  and  shaking mechanism of
fabric filters ?nd electrostatic  precipitators.   Furthermore,
processes such as sonic agglomeration are quite  sensitive to
changes in dust loading.^
          10.  Dust Solubility -  This factor  is  important re-
 garding absorption and scrubbing.  In absorption, which relates
 to uet collectors, the degree of solubility  is  an indication
 of the ease of removal of the contaminant.   In  scrubbing,  solu-
 bility will provide a secondary  removal  mechanism to  assist
 the basic separating forces.
          11.  Dust Sorbabilitv - Sorbability, or the  ease  with
 which a contaminant can be removed in wet collectors  by absorp-
 tion,  is a function of temperature,  pressure of  the system,
 chemical composition of the dust and  sorbent and also solubility.
 The effect on efficiency varies depending on the interaction of
 these factors.
          12.  Electrical Properties  of Dust - Electrical and
 sonic  properties are an influence in  collector performance as
 the following evidence indicates:
               Electrical properties are considered to be
               a contributing factor  influencing the build-
               up of solids in inertial collectors.  In
               electrostatic precipitators, the electrical
               properties of the contaminant are of paramount
               importance in determining collection efficiency
               and influence the ease with which it is removed
               by periodic cleaning.    In fabric filtration,
               electrostatic phenomena may have direct and  ob-
               servable influence upon the process of cake
               formation and the subsequent ease of cake removal.
               In spray towers or other forms of scrubbers  in
                                                                                                  A T KEARVEV & COMPANY

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                                                      VII  - 49
                which liquid droplets ace formed  and  contact be-
                tween these droplets  and  contaminant  particles  is
                required for particle collection, the electrical
                charge on both particles  and droplets is  an  im-
                portant process variable.   The process is most
                efficient when the charges on the droplet attract
                rather than repel those on the particle.   Sonic
                properties are significant where  sonic agglomera-
                tion is employed."

          13.  Dust Toxicity - The degree of dust toxicity

will influence collector efficiency requirements  and  may  neces-

sitate the use of equipment that provides exceptionally high

efficiency.  However, the removal mechanism of the collector

is not affected hy toxicity.

          14.  Particle Size. Size Distribution.  Shape and

Density - The size, shape and density of  particles are the pro-

perties that determine the magnitude of forces resisting  move-

ment of a particle through a fluid.  These forces are a major

factor in determining the effectiveness of removal by collection

systems.  Furthermore, these forces are balanced against  some

removal force applied in the control device and the magnitude

of the net force  for removing the particle will determine the

effectiveness of  the collection equipment.

           Size, shape and density of particles are related to

terminal settling velocity which is significant in selecting

control equipment.  This relationship is expressed by Stokes

law which  equates the velocity at which particles fall at a

constant speed because of a balance of the  frictional drag

force and  the downward force of gravity to  the properties of

the particle and  the viscosity of the fluid  through which it
                 A T KFM»"EY 8. rOMI'*VY Isr
                                                                                                                                            VII  - 50
settling.  The equation for Stokes law is:

              Vt - Ppgdp2/18uf

     where:   Vt = terminal settling velocity  in centimeters/
                   seconds

              Pp - particle density in grams/cubic centimeter


              g = acceleration due to gravity  in centimeters/
                  seconds 2

             dp » particle diameter in centimeters

             uf = fluid viscosity, poise  in grams/centimeter
                  second

          This equation is for particle sizes  less than  100

microns.

          Particle size and size distribution  are especially

significant with regard to collection efficiency as shown below;

              Any dust collector, operating under specific
              flow conditions and with a  given gas, will
              have a collection efficiency corresponding
              with each particle size or  particle size-  ,g
              distribution passing through the collector.

Particle size distribution of dusts found in air pollution work

satisfies the normal standard distribution curve.

          Additional conclusions on the effects of particle  size

on efficiency appear relevant.

              The effect of particle size on efficiency
              of a collector can be demonstrated by col-
              lecting dust samples on the inlet and out-
              let of the operating collector.  Knowing
              the Inlet and outlet dust concentration
              and the inlet and outlet size distributions,
              collection efficiency can be plotted as a
              function of particle size on arithmetic
              coordinates.  The resulting plot, known as
              a. "size-efficiency" curve,  describes the
              performance capabilities of the  collector
              in question when operating  at stated gas
              flow conditions (velocity,  viscosity, etc.).
                                                                                                     A  T K F * P V I? •>

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                                                      VII  -  51

              The collector would have a different "size-
              efficiency" curve for each new gas flow
              condition, but the curve would remain un-
              changed  for different dust concentrations
              and different size distributions.  Thus,
              for any  particle size passing through a
              given collector, a definite and predictable
             - collection efficiency will be observed, flow
              conditions remaining constant.  "Size-
              efficiency" curves are especially useful in
              predicting overall collection efficiency for
              a  specific dust having known size-distribution
              characteristics.17
          Typical examples of how particular gas  cleaning
equipment efficiency is affected by particle size and particle
size distribution is presented  in the following discussion.
          Exhibit VII-25 gives  the typical  grade  efficiency
curves for a high efficiency cyclone and electrostatic  precipi-
tator.  The density of dust that the curves are based on is  2.7
grams per cubic centimeter.   Fractional  efficiencies  for various
micron size ranges were then read from these curves and applied
to a standard test dust shown in Exhibit VII-22.   These results
are shown in Exhibit VII-26.
          As shown in Exhibit VII-26,  the percent of  dust dis-
tribution in each micron size range times the percent efficiency
for that range gives an overall  collection  efficiency per range.
The sum of these individual  range efficiencies  equals the over-
all efficiency for the collector.   In  this  particular test,  the
cyclone collector was  followed by an electrostatic precipitator
in one total installation rather than  each  system tested in-
dividually.
          Particle size has  an interesting  effect on  efficiency
of fabric filters, as  Exhibit VII-27 indicates.   Theoretically,
                 A T KF^RVFY ft r n M P \ VY 1 * <•
                                                       VII - 52

efficiency is approximately  100% at zero micron  size  but dips
down to 10% for 0.9-micron particles  and then  increases back to
1007. again at 1.6 microns.   The reason  for  the dip is that
impingement and diffusion effectiveness is  lowest  at  approxi-
                           14
mately the 0.9-micron size.
          Another interesting effect  that particle size (and the
length of time a fabric is in use) has  on fabric filter per-
                                         18
formance is also shown in Exhibit VII-27.
          When new fabric has been placed in service, efficiency
will be low until dust cake  builds up.  After  cleaning, once
the fabric is loaded, there  is still  sufficient  dust  adhering
to the fabric to maintain the dust mat  needed  for  efficient
collection and the collector will perform in the normal operat-
ing range.
          The relationship of particle  size, pressure drop and
efficiency of venturi scrubbers  is shown  in Exhibit VII-2B.
          As shown,  pressure drop has a significant effect on
efficiency with respect to all  particle sizes

 Combustion
   Devices
      In  addition to basic emission control equipment systems,
 combustion devices can be used to control foundry pollutants.

      (a)  Afterburners
      This  equipment, used on cupolas, can consist of a combustion
 chamber, gas burner, burner controls and temperature indicator.
 In an afterburner operation, contaminated gases are mixed thor-
 oughly with the flames and the burner combustion gases in the

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                                                    VII  -  53
afterburner throat.   Next,  the gases  pass  into  the main section
of the afterburner where velocity is  reduced.   Combustion re-
action is Chen completed and the incinerated  air  contaminants
and combustion gases pass out of the  cupola.
     It is important to position afterburners properly so that
complete mixing of gases will be achieved.  In  addition, suf-
ficient oxygen must be available to burn all  combustible con-
taminants completely and ignition time  has to be  provided in the
cupola stack.  A distance from the top  of  the charging door to
the top of the stack of at least 25 feet is usually  required for
proper combustion.

     Afterburners are used to complete  oxidation  of  combustible
contaminants in cupola melting operations. In  this  regard, the
burning of carbon monoxide into carbon  dioxide  reduces the ex-
plosion hazard.  Afterburners also reignite gases that may be
extinguished by a cupola charge or charging bucket.   The  ad-
vantage from a public relations standpoint of a reduced  discharge
appearance by using atterburners usually will outweigh  the  for-
mation of some additional dust particles through the reduction
of coke cinders to ash.
      Efficiency  of afterburners  essentially  depends on the de-
 gree of mixing of contaminated gases with the  flames and burner
 combustion gases within the afterburner unit.  Also important
 in this regard are operating temperature,  retention time of
 gases within the 'afterburner and concentration and  types of
 contaminants to be burned.
                                                     VII - 54

     Afterburners are often used in conjunction with basic
emission control equipment systems.  They are especially useful
when the cupola charge contains oils, as the greater portion of
visible smoke comes from unburned oils.
     Afterburners have limitations in that cupola exhaust gases
with carbon monoxide in certain concentrations need  to be in a
temperature range of approximately 850°  to 900°  F.   This is
important since exhaust gases must be heated  to  approximately
1200°  to 1400°  F to initiate oxidation which  means  that  fuel
costs  for operating afterburners  can be  excessive  if too much
heating is required.1'  6>  l9   Exhibit  VII-29 illustrates a typi-
cal afterburner unit.

      (b)  Catalytic
          Afterburners
      This  process,  used on bake ovens,  consists of an after-
burner housing containing a preheating section, if required,  and
a catalyst  section.   Frequently,  contaminated gases are delivered
 to the catalytic afterburner by the fan exhausting the oven.
The gases  then pass into the preheat zone where they are heated
 to the temperature required to support catalytic combustion.
 Here, some burning of contaminants usually occurs.  The preheated
 gases then pass through the catalyst bed where  the remaining
 combustible contaminants are burned.
      The purpose of the afterburner is  to complete  the oxi-
 dation of combustible gases to an odor- and color-free condition
 before exhausting them to the atmosphere.  These gases will
                                                                                                  n, T I r • P V 1- V

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                                                    VII - 55
burn at a temperature of 650 -1000°  F,  in  Che presence of a
suitable oxidizing catalyst, such as platinum.  A significant
savings in fuel cost can be realized in the preheating of com-
bustible gases to this lower temperature instead of the
1500°-2000° F required without  a  catalyst.

     Efficiency of catalytic combustion units depends on several
factors.  Contact of gases with the  catalyst, uniform flow of
gases through the catalyst bed, temperature, catalyst surface
area, nature of materials being burned  and oxygen concentration
are important in this regard.
     A limitation of catalytic  units is that, because of some
materials of construction, these  devices cannot be operated at
                                                     1  19
temperatures necessary to produce complete combustion. '
Exhibit VII-29 depicts a catalytic combustion device venting a
core baking oven.

APPLICATION OF EMISSION
  CONTROL EQUIPMENT SYSTEMS
  TO FOUNDRY PROCESSES
     Although the majority of gray iron foundries currently do
not have collection equipment systems for control of emissions
from melting operations, the number  of  installations of these
systems has increased rapidly the last  few years.  The 1967
survey conducted by the Business  and Defense Services Adminis-
tration and the National Air Pollution  Control Administration
indicated that 204 of 1,376 foundries had  some type of emission
control system for melting processes.  Current estimates appear
                                                      VII - 56

                                                   20
to indicate this figure has approximately  doubled.     A
tabulation of different emission collection  equipment designs
and their particular application to  foundry  processes is shown
in Exhibit VII-30.
     In addition to the many dust collection equipment systems
in use, a variety of hoods, ventilating and  exhaust  systems
and various other techniques are employed  to capture or exhaust
foundry emissions.

     For purposes of discussion, the iron  foundry  has been
divided into areas of activity in which characteristic emission
control problems occur.  These are as  follows:
          - Raw material handling, preparation  and charge makeup.
          - Cupola melting.
          - Electric arc melting.
          - Electric induction melting.
          - Other types of melting.
          - Inoculation.
          - Mold pouring, cooling and  shakeout.
          - Sand preparation and handling.
          - Cleaning and finishing.
          - Coremaking.
          - Miscellaneous areas.
Raw Material Handling,
  Preparation and Charge
  Makeup	
     The charge yard and charge makeup areas  in most  iron

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                                                      VII  -  57
foundries have not normally been considered important  sources
of air pollution and therefore, with rare  exceptions,  have not
had air pollution control systems installed.   This has occurred
for two reasons.  Most of the emissions  which come from  these
areas are dusts of relatively large particle  sizes which settle
readily.  Second, few "ixed emission points exist in typical
yards where control can easily be applied.   In a  few cases,
ventilation systems and dry centrifugal  collectors have  been
installed in the charge makeup area, where  it is  located inside
an enclosed building.
     The one area which has been receiving  attention in  recent
years Involves those foundries in which  metallic  charge  materials
are either burned to remove nontnentallic coatings or accompany-
ing nonmetallic debris, or are preheated to remove moisture or
oily coatings.  Since these operations are  almost always per-
formed in a fixed combustion unit of some  type, emission
control systems are relatively easy to apply.  Medium  energy wet
collectors have been used where oil fume and  vapor were  present,
and dry centrifugal collectors were applied where dry  dusts
existed.

Cupola Melting
     Because of the widespread use of cupolas for melting, the
severity and complexity of the cupola emissions problem, the
difficulty of determining the nature and amount of emissions,
and the generally high collection equipment costs, more  attention
has been devoted to emission control of  this  foundry process
                                                                                                                                           VTI - 58
than any other.   The presence of these factors as well as other
variables such as the wide range of cupola operating character-
istics has resulted in more control methods and techniques being
employed on cupolas than on any other foundry process.  In fact
every known method, from simple spark screens to complicated
systems such as electrostatic precipitators , has been tried
with varying degrees of success.  Although selection of clean-
ing equipment varies with the purpose of the installation,
recent attention has centered on those techniques which have
been most successful in high efficiency control of emissions,
such as high energy wet scrubbers and fabric filter baghouses.

     The problem of selecting gas cleaning equipment for cupolas
depends essentially on the degree of efficiency required, need
to meet existing pollution codes, and the economic factors of
capital and operating costs.
     Vet caps, dry centrifugal collectors, wet collectors,
fabric filters and electrostatic precipitators are the different
collection systems which have been used for cupola emission
control.

     In the following paragraphs, the principal types of equip-
ment in use on cupolas are briefly described.
      (a)  Wet Caps
     These collectors, used more frequently on cupolas than any
other type, are placed directly on top of cupola stacks and thus
do not require any gas-conducting pipes and pressure-increasing

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                                                      VII  -  59
blowers.   Wet caps are most practical in plants having an
existing supply of low cost water and the ability  to dispose
                                 4
of collected dust in sludge form.   Furthermore, some type of
wet cap system is often employed in conjunction with high energy
wet collector installations on cupolas.

     Approximately 95 gray iron foundries were reported to have
                        20
cupola wet caps in 1967.

     Once the most popular type of cupola emission control, the
low efficiency of the wet cap has caused  it  to decline in use
in recent years.   Progress is now being made in developing
higher efficiency wet caps with multiple  spray sections.

     (b)  Dry Centrifugal
          Collectors	
     These low energy units are designed  for light to moderate
particulate concentrations.  In a cupola  installation, ductwork
and an exhaust fan to draw gases to the collector are required.
These systems also necessitate capping the cupola and install-
ing a cooling spray to reduce the temperature of exhaust gases
flowing to the collector.   Often, dry centrifugal units are used
as precleaners of hot blast cupola top gases prior to feeding
                   21
into a recuperator.    Furthermore,  this  type of collector is
an integral part  of most high efficiency  emission collection
systems.  In 1967, approximately 15 gray  iron foundries re-
portedly had dry  centrifugal installations which were not part
of a larger cupola emission collection system.  The low effi-
ciency of the dry centrifugal collector has  resulted in almost
                                                                                                                                       VII  -  60
no new installations on cupolas  in  recent  years,  unless they
were part of a  larger system.

     (c)  Wet Collectors
     Several different medium  and high energy designs have
been applied on cupolas.  A wide range of  capacities and
collection efficiences is available.   These  systems  are usually
used where moisture and/or high  temperature  are  present in the
emission.  A complete installation  requires  ductwork, an exhaust
fan and capping of the cupola.   As  with wet  caps,  these systems
are most practical where low cost water and  sludge disposal
                        4, 21
equipment are available.       Although only  30 gray iron found-
ries were reported to have cupola wet  collectors in  1967,  recent
trends indicate that installations  of  this type of system are
increasing more rapidly than any other.

     (d)  Fabric Filters
     When cupola collection efficiencies of  99% or higher are
required, fabric filters are often  selected.   Although various
fabric materials are available,  glass  fabric  is typically chosen
because of its resistivity to  high  temperatures.   Complete
installations can include numerous  components  such as a baffle,
raised cupola stack and lid, ductwork,  exhaust fan,  spray
coolers and other items in addition to the fabric  filter unit.
Another type of installation involves  using heat exchangers
instead of spray coolers.   Fabric filter units can be installed
                                          21
to handle more than one cupola if desired.     Approximately 39

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                                                     VII - 61
gray iron foundries were  reported  to  be equipped with fabric
                           20
filters on cupolas in 1967.
     (e)  Electrostatic
     	Precipitators
     Rare applications of these  systems have been made on
cupolas.  Excessive co ts, and operating  and maintenance problems
have limited the use of  these  systems.     Only one gray iron
foundry was reported to  have a cupola electrostatic precipitator
                     2O
installation in 1967.    Additional installations have been made
in the past few years.
     (f)  Other Techniques
     In addition to application  of the major classes of collec-
tion equipment, afterburners and preheaters can be used to
control emissions from cupolas.
          1.  Afterburners - In  cupola installations, after-
burners or gas igniters  can be employed for burning the com-
bustible top gases, thereby reducing  the  opacity of particles
discharged from the stack and  for  eliminating explosion hazards
from cupola gases.  Afterburners are  located just below or
                           21
opposite the charging door.
          2.  Preheaters - Burning of unburned products of
combustion can also be accomplished at times with a type of
blast air preheater which burns  exhaust gases from the cupola.
Not only is thermal efficiency of the cupola capable of improve-
ment, but the preheater  acts as  a  settling chamber for collect-
ing coarse dust.
                21
                 A  T  K r v P «c r v * r n M p» v > ? ^ -
                                                     VII  -  62
Electric Arc
  Melting
     Compared with the cupola, electric arc melting has  in the
past received a great deal less attention regarding air  pollution
control for several reasons.  Many of the emission  problems for
this process had already been substantially resolved with
existing designs of equipment.  Furthermore,  electric arc melt-
ing accounts for a relatively small portion of  total foundry
melting in the United States, although this percentage is
increasing rapidly.  Finally the emissions from electric furnaces
are substantially less than from the cupola.
     A number of differences exist between the  electric-  arc
and cupola air pollution problem which are significant regard-
ing control techniques.  First, the electric  arc melting process*
and emissions problem are less complex.  Second, since the
average particle size of electric arc emissions is  considerably
smaller than that of the cupola, different collection objectives
exist.  Finally, more uniform electric arc operating condifiioio
and lower total emissions tend to simplify the  design of control
equipment for this process.
      (a)  Emission Collection
     _ Equipment _
     In 1967, approximately 24 gray iron foundries  were  reported
to have some type of air pollution control equipment for
electric arc melting processes,   but the number of installations
has increased substantially in the last few years.

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                                                      vir - 63
          1.   Fabric Filters  - Of the major categories  of
emission collection equipment, fabric filters are  best  suited  for
electric arc  furnaces and have been most frequently applied.   This
is due to the extremely fine  particle size of dust and  fume
emitted from electric arc furnaces.  Complete installation of  a
fabric filter unit to w*ie furnace includes ductwork,  an exhaust
fan to draw gases to the collector and a means of  collecting
the gases from the furnace. l  Approximately 20 gray iron  foundries
reportedly had fabric filter  installations on electric  arc melt-
ing in 1967.
          2.   Wet Scrubbers and Electrostatic Precipitators  -
These collection systems are  rarely used on electric arc furnaces.
Wet scrubber limitations include the existence of  too much  fine
dust and high energy requirements.  Electrostatic  precipitators
can encounter exhaust volumes too low for their design  require-
ments.   Four foundries were reported to have wet  scrubber instal-
                                                  20
lations in 1967 on electric arc melting processes.

      (b)  Furnace Hoods
     Electric arc furnaces are also equipped with various types
                              19
of hoods to capture emissions.    Arrangement of electrodes  and
gear above the furnace  top as well as the charging and  operating
method  largely determines  the hood type applied.  Often, some
type of hood is used  in conjunction with an  emissions collection
system.
          1.  Full Roof Hood  - This  type of  hood is attached to
the  top  ring of  the  furnace.  It  requires stiffening to prevent
sagging  at high  temperatures  and  protection  of electrodes to
                                                                                                                                        VII - 64
prevent short-circuiting.
          2.  Side Draft Hood - Another design often employed  is
the side hood.  This unit is located on the side of the roof
close to the electrodes to produce a lateral type of control.
An overhead hood at the charging door is also often used with
the side hood.
          3.  Canopy Hood - Canopy hoods are located above  the
craneway, and do not interfere with furnace operating  procedure.
Effectiveness of these units is limited though, due to equip-
ment requirements needed to handle the large volumes of infiltra-
ted air.21
     (c)  Other Methods
          1.  Fourth Hole Ventilation - In this system, a  water-
cooled probe is directly connected to the furnace roof.  The
probe maintains a carefully controlled draft in the  furnace
body.
          2.  Snorkel  - This technique is similar to  the  fourth
hole ventilation method except that the extra hole  serves  as  a
natural  pressure relief opening for the furnace.

Electric Induction
  Melting	
     Very little attention has been directed toward  control of
emissions from electric induction melting furnaces.   Since no
combustion  and only  limited metal oxidation occur in  this  type
of  furnace  and because relatively clean scrap is used  for  charge

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                                                     VII  - 65
material, no serious emissions problem exists  for  induction
melting of iron.   Induction furnaces  normally  operate with a heel
of liquid metal,  and for this reason, metal  scrap  must be dry  and
free of oil.  Gas fueled dryers and preheaters have  been used  to
achieve this condition, often with operating cost  benefits
resulting from the use of the lower cost fuel  to preheat the
charge.  The burning of oil residue on the scrap produces ob-
jectionable emissions requiring the use of emission  control equip-
ment.  Afterburners and wet scrubbers, either  separately or in
combination, are often used to reduce these emissions  to accept-
able levels.  With oil and other combustibles  removed  from  the
furnace charge, emission control equipment is  not  required  on
induction melting furnaces to satisfy current  codes.

Other Types
  of Melting
     The other principal type of furnace used  for  melting  of
duplexing of iron is the stationary or rotating, fuel  fired,
reverberatory furnace.  The stationary furnace, often  referred
to as the *ir furnace, was once universally used for duplexing
when producing malleable iron.  Its use has declined with  the
increase in production of ductile iron, but it is  still found  in
malleable iron foundries.  The emissions from this type of furnace
come principally  from  the combustion of coal oil or gas fuel,
plus some slag and  iron oxide which  is carried up the  stack with
the  products of combustion.  The older installations all exhausted
into the atmosphere  through a  stack  or chimney.  Medium energy
wet  scrubbers and fabric filter bag  collectors have been applied
in a few cases.
                                                                                                                                         VII - 66
     The rotary reverberatory furnace has been only recently
utilized in small installations in iron foundries.  Since a
small quantity of emission in the form of waste products of com-
bustion and slag particles is given off, these installations  are
not equipped with collectors.

Inoculation
     (a)  Ductile Iron
     	Production
     Original installations for producing ductile  iron  by mag-
nesium treatment either exhausted directly into the foundry build-
ing, or were equipped with a ventilation hood which then exhausted
into the atmosphere.  In recent years, these stations have been
equipped with collecting hoods, or have been installed  in
enclosed rooms, and the resultant gas is drawn off by means of
an exhaust fan, into a dust collection unit.  Medium energy wet
scrubbers and fabric filter baghouses have been used  for emission
collection in this area.
     (b)  Mechanical Property
          Improvement by
     	Inoculation	
     Since inoculation in this area  produces no major  emissions
problem, emission control techniques have not been applied.

Mold Pouring, Cooling
  and  Shakeout	
     Control of emissions resulting  from pouring  and  cooling  of
molds  has been common for several decades for those  high  volume
production foundry installations where  finished molds  are  set out

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                                                      VII - 67
on continuous car-type mold conveyors, providing fixed locations
for pouring, cooling,  and  shakeout  operations.  With this type of
equipment, side draft  hoods are  often provided for the pouring
area and side or bottom draft  hoods at the  shakeout, with the mold
cooling conveyor between these two  points fully hooded with sheet
metal.  Ducting is commi nly provided from each area to a single
control device, usually a  wet  scrubber or dry centrifugal
collector.
     Collection systems have been,  and still are, uncommon for
those smaller production and jobbing foundries where completed
molds are set out on the foundry floor or on gravity roller
conveyors, and where the pouring and cooling utilize a sub-
stantial percentage of the molding  floor.   The problem for this
type of operation is related more to the cost of capture of the
emissions with a minimum amount  of  infiltrated air, than to
separation of the emission. With pouring and cooling in non-
fixed locations, without hoods to capture emissions, a large part
of the air in the foundry would  require handling.  The cost
would be prohibitive due to the  volume to be processed.  A
partial solution to the problem in  the pouring area of non-
ferrous foundries has been provided by a  traveling vent attached
to the pouring ladle bail, and ducted by means of flexible tubing
and  specially designed connecting ducts  to  a suitable emission
control unit.  This technique  permits capture of emissions result-
ing  from mold pouring with a minimum of  infiltrated air.  It is
possible  that similar methods  could be used in iron foundries.
                                                                                                                                             VII - 68
Additional  venting is required during subsequent cooling, how-
ever,  and this  is  not practical when the ladle is moved on to
pour the next mold,  with the result that significant emissions
are still not collected.

     Large  casting?. such as automotive dies and machine beds,
can be cast by  the full mold process.   Generally, no central
pouring station is provided  and the smoke generated is released
directly into the  foundry building, creating an in-plant
problem.
     The current method for  controlling the smoke is through
the use of  ventilating fans.   A properly designed arrangement
of fans and makeup air systems may  produce a relatively clear
shop environment,  but as  the  emissions are exhausted from the
foundry, an air pollution problem is created.   The problem is
further complicated  by the fact that ventilating fans exhaust
large volumes of air and  are  not designed to be connected to a
duct and collector arrangement.

Sand Preparation
  and Handling
     Processes  such  as mechanical sand handling systems and sand
mixing or reconditioning  produce emissions that have received
attention over  the years.  Since most  gray iron foundries make
green sand  molds that  produce  moisture when the mold is poured,
medium energy wet  collectors are best  suited for effluent
control.  Occasionally, cotton or wool fabric  filters are
employed only when dry  sand conditions  exist.   Also,  medium

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                                                    VII - 69

energy dry centrifugal collectors  are  sometimes used.  Often,
some type of hood is used to capture emissions in sand con-
veyor systems especially at transfer points.  As with many
other processes, ductwork and an exhaust  fan are required in a
complete collection system.

Cleaning and
  Finishing
     The various cleaning and finishing operations  produce a
significant emissions problem that has received considerable
attention regarding control.
     Dusts from gate and riser removal are  generally controlled
with local exhaust systems connected to dry centrifugal collec-
tors, medium energy uet collectors, or possibly fabric filters.
Sometimes exhaust hoods are provided above  the work station.
Other cleaning processes such as abrasive shotblasting and
tumbling are commonly controlled with  fabric  filters or medium
energy wet collectors.  Applications of dry centrifugal
collectors are also made for abrasive  cleaning processes.
     Most of the trimming and finishing operations  generate
emissions and require control.  Chipping  and  grinding operations
are normally provided with local exhaust  hoods connected to
either high efficiency centrifugals or fabric  filters.  Wet
collectors are used if central sluicing systems are employed
or where grinding exhaust is combined  with  other cleaning room
operations.
                                                                                                                                         VII - 70
     Surface painting requires ventilation to reduce the hazard
due to volatile materials being atomized in the air.  Exhaust
systems are generally used where dip painting is performed.
Open tank installations are also provided with local ventilation
hoods.
     Heat treating furnaces for malleable!zing or  for other
treatments of iron castings present the usual problem of
emissions from combustion of liquid or solid fuels except  where
electric or gas fired radiant tube heating is concerned.   In
most foundries, these are exhausted into the foundry building,
or through a stack to the atmosphere.  Medium energy wet
scrubbers are an  effective means of cleaning coal  burning
exhaust gases, but have not been applied in many cases.

Coremaking
     Efforts have been made to  control certain coremaking
emissions, but the gases emitted from bake ovens  and  shell
core machines are a  serious problem difficult  to  control.
Usually these gases  are permitted  to exhaust  to  the atmosphere
through a ventilation system.   Sometimes, catalytic combustion
devices are used  on  core ovens  to  burn gases  to noncotnbustible
analysis.
      Other coremaking processes present  a  less  serious  air
pollution problem capable of control.  In coreblowing or core-
shooting, fabric  filters are usually selected  if  control equip-
ment  is desired.  In rare instances, medium  energy wet  collectors

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                                                     VII - 71
are used.  For core grinding, fabric filters and medium energy
dry mechanical collectors and wet scrubbers are frequently
selected.
Miscellaneous
  Areas
     Finally, emission control equipment is applied in certain
non-manufacturing areas in foundries including pattern shops and
crating  or boxing for shipping, where woodworking operations
occur.   Dry centrifugal collectors are commonly used to collect
wood dust and chips  from  these operations.  Machine shops and
metal  pattern shops  usually  present problems of collecting
dust from machining  or grinding of cast iron.  Dry centrifugal
collectors are  commonly used for  this purpose.

CASE HISTORIES OF
  ATTEMPTS TO CONTROL
  EMISSIONS IN IRON
'  FOUNDRIES _
     Although there were individual attempts to eliminate or
control  foundry emissions before World War II,  the serious
efforts  at emission control  started about 1945.  Initial efforts
concentrated on removal of undesirable dust and fume from
Inside the foundry buildings and from work a teas where large
           of emissions were -generated.  Tbe principal means of
accomplishing  this was  to simply ventilate the buildings and to
eXhaust  the emissions to £he atmosphere.  As Che problem
           in severity,  many foundries begarv -to -appiy existing
         of dust colLecttDH-«^ai-pment to individual emissions
.producers _in the  foundry.  Gradually, the designs of dust
                                                                                                                                           VJI -_Z2_
collectors began to be directed toward  the  individual foundry
requirements, and the present types  of  equipment began to
evolve.
     The history of the development  of .foundry emission control
has been traced fr -m actual case  histories  which were obtained
from .reports "f p.iM'if ig°n"1°r,  -\»t? -from  equipment manu-
facturers, published articles, and  private  sources.
     Because of the differences in  the  historical development
of emission control equipment for various foundry processes
over the years, .tne-dlsciission is diuided into t-we sections:
(a) melting  processes and  (b) non-melting processes.

Melting Processes
     Prior to the  1940's,  emission  control  techniques for the
cupola, which was  the principal melting practice employed at
the time, essentially consisted of  screen cage spark and dust
arresters or chain  barriers.  The screen cages, placed on top
of cupolas,  were simple and inexpensive designs, primarily
used for reducing  the emission  of cinders that caused damage to
fraiynliy rojofs, g"«•«•»«•«= .aaJ rifTMnTr""""" -asd uhioh were also a
nuisance to  the immediate .area.   Some cinders were removed,
but since screen cages were coarse  to  prevent excessive resis-
tance  to gas  flow,  this technique did  little in catching the
          -also emitted.  r)**i*r,c suspended from weather caps
located near the top.of the cupola were even, less -effective.
                                                             21, 23

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                                                      VII - 73
     One of Che first emission  control equipment systems
employed on cupolas and the  most widely used in the 1940's
was a wet cap.   These collectors came into prominence because
they were simple,  economical systems and a major improvement
over screen cages  and chains in reducing cupola emissions that
led to roof damage and neighborhood nuisance problems.
     Success in controlling  cupola emissions with early wet
cap designs varied widely.   Some foundries fabricated their
own wet caps while others bought commercially available units.
Some foundries ex^tilanced increased cleaning efficiency with
larger amounts of  water.  Others were less successful and had
excessive corrosion and prohibitive maintenance costs when water
usage was increased in efforts  to obtain higher cleaning
efficiencies.  Furthermore,  a successful wet cap design for one
cupola installation did not  always produce similar results on
another cupola having the same  outward size and characteristics,
due to Che many variables in cupola operating condicions and the
                             21
wide range of solids emitted.
     Although the first reported  installation in  the United
                                                          24
States occurred in  1936 on a midwestem automotive foundry,
wide use of wet caps actually appear  to be an outgrowth of black-
out efforts in England during the early part of World War II.
Another reported installation occurred in  1941, but shutdown of
the foundry because of the war  prevented testing  the wet cap
system.    Many of  the initial  wet cap installations which
occurred in the early 1940's consisted of a shell and one to
three spray nozzles located near  the  top of the shell.
                                                                                                                                          VII - 74
     The first wet cap installation where  effectiveness of the
gas cleaning system was reported occurred  in  L945.   Six cupolas
at a midwestem automotive foundry were  each  equipped with a
double-cone wet cap system consisting of 70 water spray nozzles.
Although no quantitative test data were revealed,  the instal-
lation was considered successful from the  standpoint of reduced
emissions deposited on adjacent roofs and  grounds.^*
     Because of the success of the automotive foundry wet  cap
installation in 1945, the exact same wet cap  design was employed
on six new cupolas at a gray iron foundry  located in the Mid-
west in 1947.  On the first day of operation, the blast on one
cupola was turned on before the pump supplying water to the
collector could be started.  This caused the  cone of the scrubber
to become thoroughly heated, and when water entered between the
cones, the pressure pulled one of the stays out  of  the lower cone,
forcing a stream of water down into the  cupola stack.   Water to
the collector was not cut off for fear of  damage, so the bottom
on the cupola was dropped and the operation discontinued.

     Due to this unfortunate experience, the  hollow cone multi-
spray wet cap was discarded.  The difficulties with the multi-
sprays were attributed mainly to dirt, pipe scale and  boiler
scale in the mill water.   Maintenance cost was also considered
prohibitive.
     Later, the original  wet cap design  was remodeled  by
removing the upper cone and multiple nozzle arrangement and

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                                                       VII  -  75
installing a single large nozzle over the apex  of  the  remaining
lower cone.  Tests made on the cupolas with  the remodeled wet
caps showed that .09 to .13 grains per cubic  foot  of particulates
were collected.  The resulting emission levels  were lower than
that experienced by many other foundries with wet  cap  installa-
tions.

     An analysis of particle sizes was made  as  a further check
on the performance of these wet caps, and it  was found  that
about 1% by weight of the escaping particulate  matter  exceeded
40 microns in diameter.  Of the remaining 99% by weight, over
99% of the particles, by count, were  less  than  5 microns.
                                                         24
     Wet cap designs introduced in the mid-1940's, such as those
consisting of a steel cone, nozzles discharging water in a
curtain and a deflector ring,  were an improvement over the shell
design and are basically the same  as current concepts.

     In the late 1930's, attempts  were made to design other
wet-type cupola gas cleaning systems to prevent disgruntled
neighbors from bringing suits  for  property damage.  One such
attempt occurred at a New England  gray iron foundry in 1937.
Gases from two capped cupolas  were drawn downward through duct-
work by a fan to the collector.  The heavy particles sank
downward by gravity and some of the lighter particles were
removed when passed through a  water spray.  It was reported that
125 pounds of particulates per hour, consisting of coke particles,
iron oxide particles, and silicious material, were removed from
               26
the gas stream.
                                                                                                                                           VII - 76
     During  the  late  1930's and  1940's,  various  dry centrifugal
collector designs were also used on cupolas  but  less frequently
than wet caps.   Some  attention was directed  in this area,  how-
ever, because of the  advantage of gravity  and centrifugal  forces
in these systems.  Particles  too heavy to  be supported by  the
upward velocity  of the waste  gas settled back into the stack,
or into expansion-type dry collection chambers.   Fine dust
collection was poor,  and overall collection  efficiencies of
these dry centrifugal systems were in the  range  experienced with
wet caps.

     Dry centrifugal  systems  used during this period included
cyclones, impact chambers, zigzag baffle arrangements and  down-
up expansion chambers.  Problems with high temperature, corrosion
and handling the collected dust prevented  more widespread  use
of dry mechanical or centrifugal collectors  on cupolas at  that
time.

     Dry centrifugal cleaning principles proved  to be more
effective when combined with a wet cap system.   A combination dry
centrifugal, wet cap system installed on eight cupolas in  a
midwestern automotive foundry in 1948 was  reported to be approxi-
mately 90% efficient.  This system type  consisted of a flame
suppressor that introduced an atomized mixture of water and air
into the rising gases.  Then a combination cyclone-type blower
unit, conical cap and water sprays further wetted dust particles
                                           27
and washed them down into discharge pipes.

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                                                       VII  -  77
                                                                                                                                VII - 78
     During the early 1940's,  systems  to control  electric  arc
furnace emissions made use of  building roof monitors,  roof fans
and exhaust hoods.  These techniques helped reduce  fumes in the
plant by exhausting them to Che atmosphere  but  no dust collection
was achieved.

     In the mid-1940"s, foundries began to  apply  emission  control
equipment to electric arc melting processes as  the  following
case describes.  A roof-type ventilating system was installed
above an electric arc furnace  in a midwestem steel foundry in
the 1940's.  During warm weather, the  system worked adequately,
but gases and dust collected in the building during cold weather
and made working conditions unpleasant.  In an  attempt to  over-
come this problem, foundry management  Installed a wet  centrifugal
unit with a cyclone precleaner in 1945.  In 1950, oxygen began
to be used in the melting practice and this increased  contamina-
tion during injection.  When the local smoke code could not be
met due to this contamination, a battery of spray nozzles  was
added to the precleaner.  This modification reduced dust in the
airstream, but wind carried the contaminated water  over nearby
homes, causing a nuisance.  A  water eliminator  was  then added
                                                         28
to the system and it was reported that complaints stopped.
     During the middle and late 1940's, further improvements in
cupola emission control involved use of afterburners in the
cupola stack to reduce the visible black plume  from unburaed
volatiles, largely oil from scrap. Also, gas or  electric  ignit-
ers were frequently substituted for traditional wood fire  for bed
coke ignition.  The burning wood often produced an objection-
able pungent odor and smoke from partial combustion of the
residuals.
     Until the late 1940's, very few foundries had any effective
type of dust collection equipment system for control of melting
emissions.  The systems that had been installed, mostly wet
caps, were largely due to aroused public opinion of residents
located near foundries.  In the late 1940's though, the dramatic
air pollution difficulties at Donora, Pennsylvania, the adoption
of the Los Angeles Air Pollution Control District Code, increased
neighborhood complaints, publication of the American Society of
Mechanical Engineers smoke regulation and ordinance model, and
other factors prompted development of additional emission control
equipment and refinement of existing techniques.  This was the
first major concerted effort to develop high efficiency emissions
control equipment.
     Efforts to meet the strict Los Angeles County code with
wet caps and other designs previously employed during  the 1940's
proved unsuccessful.  The foundry industry and control equip-
ment manufacturers were not aware that cupola emissions contained
a large percentage of particles too small to be effectively
collected by the equipment in current use.  After many tests, it
was determined that the fabric filter was best suited  to meet
the code provisions for foundry emissions.  Fabric filters had
been used successfully for many years in other industries, but
this was the first application to foundry melting processes.

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                                                      VII  -  79
     The dramatic increase in collection  efficiency  that could
be experienced with fabric filters  is  demonstrated by  the report
on a cupola installation in Los  Angeles in  1952.  Close to  1007
of all dust was collected with a fabric filter  consisting of
crlon bags.
     However, only rare applications were made  subseqently  of
fabric filters with orIon bags due  to  temperature  limitations.
Since orlon usually could not be used  as  a  filter material  when
temperatures exceeded 275  F and because  cupola -gas  temperatures
are much higher, attention focused  on  other filter material that
could withstand higher temperatures, such as fiber glass fabric.
     Pressure on the foundry industry  by  the Los Angeles Air
Pollution District resulted in the  development  and use of glass
fabric for cupola gas cleaning In the  late  1940's  and  early 1950's.
Typical early installations consisted  of  relatively  crude designs
where 15-foot-long, 11-1/2-inch-diameter  tubes  were  suspended  to
a mechanism that was manually operated to "rock" the tubes  during
shutdown.  Production of glass cloth with a silicons lubricant
permitted this mild flexing action without  rupture of  the glass
fibers.  However, problems with bag wear  and the sensitivity
of glass fabric to flexing encouraged  development  of fabric
collectors of the reverse flow concept in the early  1950's. This
provided more effective dust removal and  continuous  operation  of
the  collector.  However, visible plumes emitting from  the
foundry stack still presented a problem.
                                                        VII - SO
      Experimental  tests  on electrostatic precipltators in the
 late  1940'8 were successful in the Los Angeles area and the
 system was in  use  in  other industries, but attempts to apply
 precipitators  to cupolas  were  unsuccessful at the time due to
 maintenance and other problems.

     Meanwhile, intensified Interest  in melting emissions con-
 trol also had  effects on  electric  arc furnaces which,were being
 installed in increasing numbers  during the 1950's.   The full
 roof hood concept  that was  used  in the raid-1940"s was  modified
 to that of a local side hood which improved control of electric
 arc emissions.  Fabric filters also began to be used for higher
 collection efficiencies.
     Nationally, there waa  a reluctance to follow the  glass
 fabric practice of Los Angeles for cupola emission control,
 especially in  the colder northern  climates.    The multiple dry
 centrifugal was introduced  for such systems  in the  mid-1950's
 and tests conducted in 1956  at a Wisconsin foundry  equipped with
 this type collector resulted in efficiencies ranging from 59%
 to 84%.29

     Some attention was directed toward other dry centrifugal
designs also,  such as  high efficiency cyclones.   Tests conducted
on this system type in the early 1950's produced  cleaning
efficiencies of 65% to 83%.    Generally  speaking,  less  success
was achieved with high efficiency  cyclones  than multiple dry
centrifugals and this  latter type was  used on cupolas  more

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                                                      VII  -  81
frequently when mechanical systems  were  selected.   Dry centrifugal
collector design concepts in use  during  the early  1950 's  for
cupolas are basically the same as current  concepts.

     In the late 1940's and early 1950's,  considerable attention
continued to focus on wet cleaning  systems for  emission control.
Even though a number of these systems  could not meet  the  strict
Los Angeles code, continued refinements,  such as capping  the
cupola to confine the gases and prevent  combustion in the stack,
and development of more complex control  techniques increased
cleaning capabilities.  For example, in  1949, a Los Angeles
foundry was able to meet existing codes  with a  cleaning system
involving a charging bell, dry centrifugal and  wet scrubber.

     In other sections of the country, many foundries were con-
tinuing to use wet caps, but performance was generally below
that obtained by foundries meeting  the strict Los  Angeles code.
A northern foundry, in 1951, installed a wet cap and  the  major
benefit was the reduction in deterioration of the  foundry build-
ing roof.  Complaints from housewives  stopped also, but some
problems were experienced with the  pump  because of the acidic
condition in the water system.

     In the mid- and late 1950's, continued public demand for
better cleaning efficiencies prompted  development  of  medium
energy wet scrubbers.  These systems were more  successful than
the lower energy wet caps, but not  as  effective in dust removal
as fabric filters.  An installation of this type on a 96-inch
                                                      VII  - 82

cupola in the early 1960's produced dust outlet  loadings of
.035 grains per standard cubic foot which was well  below exist-
ing code levels.

     Development of medium energy wet scrubbers  also  led to
applications on electric arc furnaces where  efficiencies of
approximately 75%-857. for solid particles were achieved.
Problems experienced with these systems included Little altering
of discharge appearance because of the large percentage of sub-
micron dust and corrosion from oil scrap.

     Even though dust collection efficiency was  increasing with
the development of new systems, complaints still persisted for
removal of the visible plumes from cupolas.  This encouraged
application of the high energy wet scrubber.  Although used in
other industries since the early 1950's, it appears that the
first cupola installations were put in service by an  automotive
foundry in the mid-19601 s, using below charge door  gas take-off.
At least one installation of that time period condensed the
water vapor ahead of the exhaust fan to provide  for a smaller
fan and drive motor and, at the same time, eliminated the  dense
steam plume.^

     Actual results that could be achieved with  this  system
type were demonstrated by a high energy venturi  scrubber instal-
lation in an Indiana foundry in 1967.  Emissions were controlled
to about .1 pounds/1,000 pounds of gas or  .05 grains  per standard
cubic foot.33
                                                                                                  A  T  k F \ n v r v

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                                                       VII - 83
     In another example, a medium energy  flooded bed wet  scrubber
tested early in 1969 showed that  New Jersey air pollution codes
probably could not be met.  The results of 5 tests averaged
274 pounds/hour of emissions whereas code standards allowed 205
pounds/hour.  The problem cited was  that  the cupola was not
                                                    y
functioning according to design operating conditions.     In
an effort to correct the problem, the collector was upgraded to
a high energy unit in August, 1969.  Collector modifications
made were:
           - Addition of a high energy fume agglomerating section
 in the original scrubber housing.
           - Provision for the  use of 15  to 20 GIW liquor per
 1,000 CFM of gas.
           - Installation of a  new fan impeller.
      Tests made after the modifications  Indicated emission
 levels of approximately 125 pounds/hour--we11 below the exist-
 ing code.
          35
      In the 1960's, foundries  continued installing wet caps be-
 cause of their simple,  inexpensive design and collection capabili-
 ties regarding larger dust particles.  Replies to a survey con-
 ducted by the American Foundrymen's Society, which was documented
 in 1967, indicated that some  foundries were satisfied with per-
 formance of their wet caps while  others were not.  Most of these
 wet caps were installed to prevent nuisance or damage to the
 immediate plant property.1
      Some foundries that previously Installed wet caps modified
                                                                                                                                           VII - 84
 their  cleaning systems  when local codes became more strict.  For
 example,  management  of  a  large midwestern production foundry was
 faced  with a  problem of reducing emissions from its 2 60-inch
 hot  blast cupolas  that  were already equipped with wet caps.
 In 1968,  a variable  annulus  scrubber was added to the system
which, when tested,  resulted in an  emission level of .12 grains/
 standard  cubic  feet  (.23 pounds dust/1,000 pounds gas).   The wet
 caps were  provided with high efficiency non-clogging multiple
 flight nozzles  and corrosion resistant  deflectors to augment
 the oeripheral water curtain.   The  modified collection system
 increased  previous efficiency  levels by 50% in terms of weight
                     36
of solids  collected.

     Fabric filters were also  often applied on cupolas during"the
1960's.  Many of these were  on the  West Coast  where  codes were
strict.  This system was an  improvement over initial designs, and
glass bag  material, because  of its  higher  temperature resistiv-
ity, was  the usual selection.   Reports  from two California  foun-
dries and  one in the Midwest,  that  installed fabric  filters in
the 1960's, indicated collection efficiencies  of  over 98%.   One
of these cases cited high maintenance costs  due to bag  replace-
ment, but  another reported maintenance  costs to be low.1'"  37» 3B

     Replies to questionnaires distributed by  the American
Foundrymen's Society, and documented in 1967,  indicated  that
foundry management felt fabric  filter performance was good.  One
case was reported where bags could not  be kept  in repair  because
of seam splitting and the foundry intended to replace  the fabric
collector with a wet scrubber.

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                                                      VII  -  85
     Renewed interest developed In the 1960's  regarding  electro-
static precipitacors for cupola emission control.  One report
on a California foundry, documented in 1967, indicated collection
efficiencies of 96.6%.   Another installation  though, on a
large automotive foundry in the Midwest, proved to be unsatis-
factory and was eventually discontinued.  High maintenance costs
                                     22
were cited in this latter case study.     Until recently, because
of high costs, maintenance problems, and operating problems,
electrostatic precipitators were rarely used  to control  cupola
emissions.  Two precipitators have been Installed in the last
18 months.  The most recent installation is reportedly  operating
satisfactorily.  No maintenance cost data are  available  because
of their short operating history.
     Some attention was directed toward use of a dry multiple
cyclone collector on cupolas in the 1960's.  Replies to the
American Foundrymen's Society questionnaire indicated that found-
ries were obtaining efficiencies from 61%-75% with such equip-
ment.  These were results from five tests on  different  installa-
tions .

      Current  trends  appear  to indicate  that high energy wet
scrubbers and fabric  filters are the  types of emission control
equipment systems usually selected  for  cupolas because of their
high efficiency  and  success  in meeting  existing codes.
      Even though present wet cap designs do not appear  to satisfy
most air pollution codes, these  systems are still being purchased
by foundries.
                                                                                                                                     VII  -  86
     In the 1960's, increasing fabric filter installations were
also made on electric arc furnaces.  An example of such an in-
stallation pertained to an eastern railway signal foundry in
the early 1960's.  The electric furnace in this foundry melted
about 3 tons per hour and was equipped with an exhaust hood
that had a 24-inch-diameter telescoping and swivel connection
to provide constant ventilation throughout melting and tapping.
The dust collector was equipped with approximately 4,800 square
feet of orIon filter cloth which provides a 1.7 to 1 air to
cloth ratio.  To safeguard the orIon bags, a bypass damper was
installed in the exhaust piping at the collector inlet.  Al-
though no exact collection figures were made available, dust
and fumes were no longer considered a problem.
                                              39
     The American Foundrymen's Society survey disclosed  that
fabric filters did a very good job of emission control for elec-
tric arc furnaces.  In one foundry, dust collected per ton of
charge was 8.8 pounds when scrap was handled manually.   After a
magnet crane was installed to  handle scrap, the dust collected
per ton of charge was 13.4 pounds.  When scrap was handled man-
ually, much of the dirt would  fall to the ground and accumulate,
while with the magnet, the dirt would enter the furnace  and exit
as dust.  Complaints concerning these fabric filter installations
included:
          -  Dry dust disposal.
          -  Bag failure.
          -  Dust buildup on the clean air side of bag.

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                                                      VII - 87
           -   Dust  sticking to the side of collection hoppers.
 Finally,  the  survey disclosed that a roof-mounted hood with
 baghouse  was  preferred to a roof tap and baghouse system.1
     Because  of the problems with controlling cupola emissions
 and other factors, some foundries turned to other melting
 processes, such as electric induction.   This trend began in the
 early 1960's and it was the general belief that  induction fur-
 naces offered relief from air pollution legislation pressures.
 At this writing, no control equipment installations have been
 reported on €?"»»dry induction furnaces.   A series of tests
 conducted at an East Coast foundry in 1968 indicated that
 coreless induction melting and a charge  preheater could  be
 operated in most installations without  pollution control devices
                                                        40
 and yet comply with existing or pending  emission limits.
 Non-Melting
  Processes
     Contrary to the many developments and refinements in melt-
 ing emission control equipment systems during  the past 25 to 30
 years, emission control of non-melting processes  such as  shake-
 out, sand handling, cleaning,  finishing,  coremaking and  pattern
 shopwork is substantially the  same now  from a  technology  stand-
 point as in the mid-1940's.   Practically  all of  the  major
emission control problems in these areas  had been resolved by
World War II except for a few improvements  which  were made in
 later years.   This appears to  have occurred for a number  of
reasons.
     First, emission control of non-melting processes has proven
                                                                                                                                    VII  -  88
to be more economical and less complicated.  Also,  these  process-
es, when compared to melting, do not contribute  as  much on an
individual basis to the foundry emissions problem.   Consequently,
less attention has recently been directed toward non-melting
processes regarding emission abatement.  Reports regarding past
attempts to control emissions in these areas are limited  in
comparison to the widespread interest in solving melting  air
pollution problems.

     Foundry cleaning room operations were among the earliest
non-melting processes where attempts were made to control or
capture emissions.  Prior to the 1930's, sand blast rooms and
tumbling mills were in extensive use and local exhaust systems
removed the dust, quantities of burned sand, scale  and spent
abrasive.  This produced a number of advantages.  First,  visi-
bility for the blast room operator was improved  and also,  since
the fractured dust fines were removed, better cleaning efficiency
of the abrasive was possible.  In addition, a shorter tumbling
mill cleaning cycle was obtained by preventing accumulations of
dislodged dust from cushioning the impact forces  of the tumbling
barrel stars.  However, it was recognized by some foundries that
discharge of such quantities of dust to the atmosphere without
collection equipment would cause a neighborhood  nuisance.
     The hollow trunion design of early tumbling mills made dust
collection feasible and dry mechanical, low energy  cyclones as
well as fabric filters were used for this purpose.   Fabric
filters were probably more frequently applied and early designs

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                                                      VII -  89
were crude, usually made of wood.   Dust collection was fairly
good but there were problems with  cloth vibration, dust escap-
ing between the fabric and the support  and  also filter media
replacement.
     Prior to the 1930's, local exhaust systems were used  for
various grinding processes especially where sand grinding  was
employed.  Dust particles torn from the cast metal surfaces
by the grinding wheels were relatively  large and low energy
cyclones or fabric filters were used during this early period.
Fabric filters were often employed when a single system was
used to exhaust grinders and abrasive cleaning or tumbling mill
operations.  Fabric filter emission cleaning efficiency was
fairly good but the use of cyclones was marginal.  Although
there were no visible particulates in the cleaned air from the
collector, oxidation of the settled material discolored buildings
and walkways in the area.  When higher  efficiency cyclones were
introduced, this became less of a problem.

     The introduction of mechanical sand handling systems  and
central shakeout equipment in the larger foundries in the  early
1930's made dust control through local  exhaust ventilation feasi-
ble.  Dust was released in great quantities in specific locations
as compared to the more general release in smaller foundries
where floor molding was usually employed.  As long as the  sand
was dry, dust could be collected with fabric filters.  However,
dry sand required baked sand molds or the storage of the poured
flask in an outdoor storage yard for cooling.  Most gray iron
castings were, and still are, made in a green sand mold and shaken
                  A  T  *F»"VrY* ' 'i "I F' \ V Y  F « r
                                                                                                                                   VII  -  90
out of the flask as the hot casting has solidified.  Under  these
conditions, steam in quantities was released by  the  hot, moist
sand.  This moisture, picked up by the exhaust air heated by
the hot castings and sand, made application of fabric  filters
impractical for most gray iron foundry shakeout  and  sand systems.
Moisture would condense on the filter surface and combine with
the sand fines to prevent an effective flow of exhaust air.
This condition was dealt with in  latter years when wet scrubbers
were introduced.
     Early foundry wood pattern shops used exhaust systems  and
later  low  energy dry mechanical cyclones  for  dust collection.
Since  particle sizes from sawdust, wood chips  and slivers  are
large,  and also because low velocities  are required, collection
was  good and  no significant problems  existed.  Through the years,
cyclones continued  to be used and are the usual  selection today
for  woodworking processes.
      Fabric  filters  have  also been employed  over the years in
woodworking  areas,  often  as a  final cleaner  when cleaned air is
returned  to  the work space during the heating season.
      The  introduction  of  wet  scrubbers in the mid-1930's improved
dust collection capabilities  in most non-melting areas including
 cleaning,  grinding,  shakeout  and sand handling.   This was  espe-
 cially significant in shakeout and sand handling processes where
 wet sand created dust collection problems.  A midwestern malle-
 able iron foundry that installed a wet dynamic  precipitator re-
 ported a collection efficiency of 99% in  1937.  This  test  occurred
                                                                                              A T K F \ R V r
                                                                                                                •I I" > N N  F ^ r

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                                             41
                                                      VII  -  91

on a shakeout operation handling four large castings per minute.
Another foundry reported a 98% collection efficiency on a  sand
mixing process with a wet dynamic precipitator.   This test
occurred in the late 1930's on the East Coast with a collector
                                     41
rated at 5,400 cubic feet per minute.    In a cleaning room
application, a wet dynamic precipitator was  reported to have
collected 99% of the dust emitted from a tumbling mill operation.
                                                        41
This occurred in 1939 at a foundry located  in Tennessee.
Successful application of wet scrubbers during the mid- and
late 1930's stimulated substantial product  development although
by the mid-1940's, designs had stabilized along  the lines  of
current four-inch to seven-inch pressure loss collectors.

     Early cleaning room practices underwent changes that  had
a favorable impact on dust collection capabilities in this area.
Tumbling mills were rapidly replaced by airless  blasting, in  the
1930's.  Also, sand as an abrasive was replaced  by grit or shot,
originally chilled cast iron but currently  cast  steel pellets.
Metal abrasive created less dust from shattered  abrasive fines
and had a higher cleaning efficiency than sand.   This became
increasingly significant when airless blast  equipment was
introduced.  The abrasive development was a  major stimulant
toward automatic cleaning devices-which by  the late 1940's had
largely replaced the manually directed hose  in a sand blast
room, except for large or occasional parts,  and  the tumbling
mills.  Most abrasive cleaning units, such  as tumbling mills,
were originally discharged to fabric filters, but when four-inch
A 7  K K * II M"
                                                                                                                    VII - 92
to seven-inch pressure loss wet collectors were  developed,  these
systems were frequently used.  The wet collectors  had advantages
especially in the larger production foundries where  central
sluicing systems were in use.
     By the late 1940's and early 1950's, advances in wet collector
designs made collection efficiencies of  97%  or higher typical
for sand handling systems.  These systems consisted  of conveyors,
elevators, screens, lines and mixers.  From  150  to 500 pounds of
dust per hour were collected.

     Over the years, many non-melting processes  were equipped
with various types of hoods to prevent emissions from discharging
into the plant.  Often, they were used in conjunction with a
dust collector.  Enclosing hoods and side hoods  are  two types
used in shakeout processes and these have demonstrated a 97%
and 90% efficiency respectively.  This was reported  in the early
1950's.42
     Reports in the early 1950's on the  use  of dry centrifugal
collectors on metal grinding processes indicated that particu-
lates were reduced to .002 grains per cubic  foot.  These processes
were usually two-wheel grinding stands and collectors captured
                                                            approximately 15 pounds of cast iron dust  per hour
                                                                                                                42
                                                                 In the early 1950*s, medium energy wet  scrubbers and fabric
                                                            filters were the usual installation on grit  blast and airless
                                                            blast abrasive cleaning processes.  Particulates  were reduced to
                                                            approximately .02 grains per cubic foot which resulted in approxi-
                                                                                                              42
                                                            mately 800 pounds of dust being captured  per hour.

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                                                       VII -  93
                                                                                                                                    VII -
     As pressures on industry to increase air pollution efforts
persisted in the 1950's and early 1960's,  foundries  stepped up
application of emission control techniques to non-melting process-
es.  More attention began to be directed to such areas  as mold
lines, coreraaking, scrap preparation and magnesium treatment  for
ductile iron production.

     In the mid-1960*s, mechanically energized wet collectors
were installed in a production gray iron foundry in an  attempt
to improve mold line ventilation.  Outlet samples obtained
yielded dust loading results that were considered lower than
usually achieved in a relatively uncontaminated factory atmos-
phere.*3

     One large foundry had suffered extensive damage when the
core ovens exploded due to exhaust stacks becoming plugged with
organic residues.  A centrifugal spray collector was installed
with facilities for adding chemicals Co react with the  organic
airborne residues.  It was reported tn 1965 that the stack
hazard was eliminated and the combustible and polymerized resins
        44
removed.

     Another example of coremaking fume control pertains to the
experience of a midwestern foundry.  In this case, a catalytic
combustion system was installed to complete oxidation of contam-
inants that had been giving off objectionable odors. Complaints
that had been raised by nearby residents ceased after the system
              45
was installed.
     In preparing scrap for melting, centrifuges were  often used
to reduce excess oil.  Driers or kilns were applied  also by a
number of foundries to drive off moisture and burn off oil  from
scrap before processing.  Furthermore, abrasive cleaning equip-
ment was used to remove burned sand from foundry returns.   This
reduced dust loss in transferring these returns between different
points in the foundry.'

     A West Coast foundry reported in the late 1960's  that  plant
conditions improved and emissions were reduced as a  result  of  a
fabric filter installation on a ductile Iron magnesium treatment
station.  Less emissions were captured when ductile  Iron was not
being produced.  This system was also controlling desulphurization.5

     Efforts continued to be directed in the 1960's  toward  con-
trol of heavy dust producing areas such as cleaning, finishing,
grinding and shakeout.

     A centrifugal spray collector controlled outlet loadings  in
a cleaning department to .003 grains/standard cubic  feet.  This
result was obtained by an outside testing laboratory in the mid-
1960 's in a high production gray Iron foundry.*

      An orifice wet scrubbing collector was installed in the
 grinding and cleaning area of a midwestern foundry in the mid-
 1960 's.   The dirty air was drawn via suction pipes from points
 near each piece of equipment.   The breathing area around each
 grinder was reported co be substantially dust free and workers
 did not require masks.   Much of the exhaust piping formerly

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                                                      VII  -  95
                                                                                                                                  VII - 96
employed at each grinding station continued  to be  used,  but
required alteration.

     A large midwestern automotive foundry recently  reduced
emissions in their finishing department to  .05 grains per stan-
dard cubic foot.  Wee collectors, centrally  located  on the plant
roof, achieved this performance.   The central location was re-
ported to permit ease of maintenance and repair.
     A midwestern foundry recently equipped  its shakeout area
with an orifice wet scrubber.  The collector was mounted on  an
overhead steel structure Chat allowed headroom in  working areas.
Dust was drawn into the collector by two fans and  after scrub-
bing, the sludge deposited onto a conveyor and then  dropped  Into
a drum for removal.  The collector, rated at 20,000  CFM  was re-
ported to have Improved operations and working conditions in the
plant.46
     In another shakeout example, tests performed  by an indepen-
dent laboratory showed outlet loadings from  a centrifugal spray
collector to be .0006 to .0007 grains per standard cubic foot.
This test was documented in 1965.**
     Dust collection equipment also continued to be  used in
pattern shops.  An East Coast foundry, attempting  to control dust
from woodworking equipment operations, installed a roof-mounted
bag collector in the 1960's.  Although no quantitative collec-
tion figures were available, it was reported that  the desired
level of air cleanliness was being achieved.   Each woodworking
machine was equipped with a hood which the dust traveled through.
before being captured by the collector.
                            REFERENCES
     L.  Foundry Air Pollution Control Manual.  American
Foundrymen's Society, 1967.
     2.  Cupola Emission Control,  translated by P.S.  Cowen
published by the Gray and Ductile  Iron Founders'  Society, Inc.
     3.  "Dust, Fume and Smoke Suppression," A. Grlndle,
Iron and Steel Engineer. July, 1951,  p.  92.
     4.  Dust Collectors. American Foundrymen's Society, 1967.
     5.  Personal Notes of John Kane.
     6.  "Available Control Equipment for  the Foundry Cupola
and Their Performance, Operations, and System Characteristics,"
John Kane, presented at American Foundrymen's Society Annual
Meeting, May 7, 1956.
     7.  "Dust Control," R. Whit lock., Ceramic Age.  October, 1965.
     8.  "Foundry Cupola Dust Collection," W. Witheridge,
Heating and Ventilating. December, 1949, pp.  70-84.
     9.  American Air Filter, Rolo-Clone-Type N.  Bulletin No.
277E, February, 1967.
    10.  Pangborn Division, The Carborundum  Company,  Air
Pollution Control by Pangborn.
    II.  American Air Filter, Reverse Jet  Fabric  Dust Collector,
Bulletin No. 279E.
    12.  "A Discussion of Some Cupola Dust Collection Systems-
Part 3," C. R. Wledemann, Modern Casting.  January,  1970,
pp. 72-74.

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                                                       VII - 97
                                                                                                                            VII  -  98
     13.  "Choosing Your Electrostatic Precipitator," E.P.
Stansny, Power. January, 1960, p.  62.
     14.  "The Design and Performance  of Modern Gas Cleaning
Equipment,"  C. J. Stairmand, Journal  of the Institute of Fuel.
February, 1956.
     15.  The Cupola and Its Operation, published by the
American Foundrymen's Society, 1965.
     16.  Introduction to Air Quality  Management. Training Course
Manual in Air Pollution, U.S. Department of Health, Education
and Welfare, pp. 8-10.
     17.  Air Pollution Manual, published by American Industrial
Hygiene Association, 1968.
     18.  Torit, Dust Collectors,  Series 130, January, 1966.
     19.  Air Pollution Engineering Manual. U.S. Department of
Health, Education and Welfare, Public  Health Service, Publication
No. 999-AP-40, 1967.
     20.  Private communication.
     21.  Control of Emissions from Metal Melting Operations.
American Foundrymen's Society.
     22.  Personal notes of James Ewens.
     23.  "Cupola Dust Collection," W. Witheridge, The Foundry.
March,  1950, p. 88.
     24.  Cupola Gas Scrubbers.  0. J. Brechtelsbauer, American
Foundrymen. February, 1955, pp. 34-37.
     25.  "Collectors on Cupolas Clean Waste Gases," 0. Allen,
The Foundry. November, 1945,  p. 89.
  26.   "Control of Cupola Stack Emissions," J. Drake and T.
nard,  The Iron Age. April, 1949, p.  88.
  27.   "Around Detroit," 0.  H. Allen, The Foundry. March, 1949,
124.
  28.   Control Emissions from the Electric Furnace. L. Krueger.
  29.   American Air Filter,  Case History Report, March, 1959.
  30.   "A Study of Cupola Design and Operating Factors That
luence the Emission Rates from Foundry Cupolas," R. C.
gies,  reprinted from American Foundrymen's Society Transactions,
5.
  31.   Cupola Fly Ash Suppression. R. M. Overstried, pp. 550-

  32,   The Study of the CVX Wet Gas Scrubber in Its Applications
Power Stations. Foundries, and Iron Ore Mills. John Tailor.
  33.   "Computerized Hot Blast Cupola Serves Induction Holding
nace in Production of Milton Iron," Industrial Heating.
ober,  1967.
  34.  National Dust Collector Corp.,  Report  No.  201, May  19,
9.
  35.  National Dust Collector Corp.,  Report  No.  216,
tember 16, 1969.
  36.  Foundry Facts, published by the American Coke  &  Coal
micals Institute,  No. 5,  October, 1968.
  37.  "Costs, Efficiences and  Unsolved Problems  of Air Pol-
ion Control Equipment,"  B. D. Bloomfield, APCA Journal.
. 17, No.  1,  January, 1967,  pp. 28-32.

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                                                      VII - 99
     38.  "Capturing Cupola  Emissions," Modern Castings. October,
1969, pp. 54-56.
     39.  "Controlling Dust  and  Fumes from an Electric Funace,"
Foundry. September,  1960.
     40.  "Induction Furnaces, Preheaters and Air Pollution,"
T. Steffora, Foundry. August,  1968,  pp. 82-86.
     41.  American Air Filter, Roto-Clone Efficiency Studies on
Foundry Dust Control, August,  1945.
     42.  "Foundry Dust Problems and Air Pollution Control,"
John Kane, Foundry.  October, 1952.
     43.  "Performance Testing Data  on Mechanically Energized
Spray Wet Type Dust Collectors," R.  Jamison, Air Engineering.
June, 1965.
     44.  Performance of Centri-Spray Wet Type Dust and Chemical
Fume Collectors, Orlan Arnold, Ajem  Labs, June 11, 1965.
     45.  "Air Pollution Problem Solved," Foundry, no date.
     46.  "Controlling Foundry Dust," G. Medley, Foundry. June,
1966, pp. 203-204.
     47.  "A Total Approach," Metal  Progress. May, 1969.
     48.  "Foundry Dust Gets The Air," Iron Age. January 21,
1965.
     49.  "Cooling Hot Gases," S. A. Keigel and L. Rheinfrank,
Jr., Pollution Engineering.  November/December, 1970.
                     VIII - ECONOMIC ANALYSIS
                  OF EMISSION CONTROL TECHNOLOGY
GENERAL
     This section deals with the costs of air  pollution  control
systems in the iron foundry industry.  Estimates have  been made
of the capital costs and operating costs of emission control
systems, based upon analysis of existing and proposed  installa-
tions.  Additionally, the capital and operating costs  of melting
departments have been developed for a variety  of types and sizes
of installations, and the effects of costs of  emission control
on the overall costs have been determined.
     The basic data used in the development of the  cost  esti-
mates were obtained from the following sources:
          1.  The in-plant surveys which were  conducted  as part
of this study.
          2.  Information supplied by selected manufacturers of
pollution control and melting equipment.  This information was
generally in the form of bid figures.
          3.  Cost information and operating data obtained in
the process of developing the foundry data bank.
          4.  Cost information and operating data from the
engineering files of A. T. Kearney & Company,  Inc.  based on
assignments in development of iron foundries.
     The cost data obtained are basically for  foundries  with
cupolas controlled with wet caps, mechanical collectors, fabric
                                                                                               A T KEARNEY «t c OMP1NV l-.r

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                                                       VIII  -  2

filters, and high and low energy wet scruubers,  for  electric arc
furnaces controlled with fabric filters,  and for induction furnaces
with preheat systems.

CAPITAL COSTS OF
  CONTROL SYSTEMS
     An emission control system was considered  to include all
items of equipment and their auxiliaries  whose  sole  purpose is
to abate atmospheric pollution from a cupola or electric furnace
in an iron foundry.  The capital costs associated with the
estimates included the following cost categories:
          - Basic Equipment
          - Auxiliary Equipment
          - Engineering Cost
          - Installation Cost
     The summation of these cost categories for a control system
constituted the total investment cost.  The cost of land upon
which the control system is located has not been included.
     The specific items included within each cost category are
as follows:
          1.   Basic  Equipment  - This cost includes all taxes
and  shipping charges in addition to the "flange-to-flange"
price of the basic equipment.
          2.   Auxiliary Equipment  - The cost for auxiliary equip-
ment includes  the cost of  all  items essential to the successful
operation of a control system.  This category has been further
                                                       VIII - 3

divided into the following subdivisions-
              (a)  Air movement equipment costs including:
                   - Fans and blowers.
                   - Motors, starters, wire, conduit,
                     switches, and other electrical
                     components.
                   - Hoods, ductwork, gaskets, and dampers.
              (b)  Liquid movement equipment costs including:
                   - Pumps.
                   - Motors, starters, wire, conduit,  switches,
                     and other electrical components.
                   - Piping and valves.
                   - Settling  tanks.
              (c)  Storage and disposal  equipment  costs
                   including.
                   - Dust  storage hoppers.
                   - Sludge pits.
                   - Draglines, trackway, and  roadway.
               (d)  Support construction costs  including-
                   - Structural steelwork.
                   - Foundation, and  piers.
                    - Insulation.
                    - Vibration and  antiwear materials.
                    - Protective cover.
               (e)   Instrumentation  costs including the
                   measurement and  control  of:
                    - Air and  liquid flow.
                    - Temperature  and  pressure.
                    -  Operation and  capacity.
                  A T KF^RVFY Sc
                                                                                            A T KEAHNTY 8c COMPANY

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                                                       VIII  - 4

              - Power.
              - Opacity of the flue gas (smoke meters,  etc.).
          3.  Engineering Cost - This cose allocates the  research
and engineering expenditures required for the selection of the
specific control system, including such items as:
              (a)  Material specification.
              (b)  Gas stream measurements.
              (c)  Pilot operations.
          A.  Installation Cost - This cost  includes the  follow-
ing items when applicable:
              (a)  Labor to install.
              (b)  Site preparation.
              (c)  Building modification.
              (d)  Design contingency.
              (e)  Field office charges including  supervision
                   and engineering.
              (f)  Inspection.
              (g)  Protection of existing facilities.
              (h)  System start-up.
              (i)  Profit reduction  attributable to  plant
                   shutdown for installation.

     Exclusive of the value of the land the  equipment is  located
on, the summation of the foregoing items represents  the total
investment required to purchase and  erect  the  pollution control
equipment, connect it to the furnace,  and  bring it into operation.
This total investment cost is the figure used  in analyzing capital
coses of Installations.
                                                        VIII - 5
      fne different installations  for which cnpit.il cost dnta
were  obtained represent  systems whose ages range from the
present to 20 or more years.  To  compensate for differences in
installation dates, investment costs were converted to a common
base  of 1969 dollars.  This adjustment was made by using the
material, construction,  and labor indices published by Engineer-
ing News-Record, March,  1970.

      The basic and auxiliary equipment costs  are the main com-
ponents of the total capital cost.   These equipment costs varied
on the average from 42%  to 66% of the total capital cost.

      The collection equipment costs  for wet scrubbers (limited
to the collector, exhauster and motor)  varied more widely as a
function of pressure drop.  These component prices are affected
by the energy required.  Increases in pressure  drop for example,
result in larger horsepower needs  which are reflected in greater
investment costs in the motor, starter, and all other electrical
components.  In the following chart,  the  relative  variation is
shown.  The reference index is unity  for  20-inch pressure drop.
      3-
           10    20    30   40    50    60
                          PRESSURE DROP
70
      80
                                                                                                     ' •» x- p % c f r« *

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                                                       VIII  -  6

     The curve illustrates that the cost  of the basic  control
equipment is more than twice as great for a 40-inch pressure drop
system than for a 20-inch pressure drop.   The relative change  from
40-inch to 80-inch is about 20%.   In addition to the basic control
equipment cost increase, there will be increases in the necessdrj
appurtenances such as electrical starters, wiring,  controls, etc.
Not included in the above curve are the costs for water clari-
fication, quencher, engineering,  cupola caps, and erection.
     The total equipment costs for scrubbers represent on the
rverage about 65% of the total investment costs. Erection costs
are about 35% of the total cost and approximately 54%  of the
total equipment price.
     The overall impact of the basic equipment costs (collector,
exhauster, and motor) on the total investment cost  is  less
significant and well within the shaded range of the investment
cost curves discussed later.  The impact of the range  in pressure
drops does, however, affect operating costs, due in part to
higher electrical energy requirements.  This will be further
covered in the discussion on operating costs.
     The following information illustrates the average ratios
and ranges observed for cupola installations.
                 A T K F \ R V F Y
                                                                                                                                      VIII  -  7
                Equipment Costs as a Percentage of
                      Total  Investment Cost	
     Control  System
     Wet Caps
     Mechanical Collectors
     Low Energy Wet Scrubbers
     High Energy Wet Scrubber
     Fabric Filter
Equipment Cost/Total Investment
AverageRange
  42%
  55%
  65%
  66%
  65%
367. - 677.
367, - 797,.
48% - 80%
487. - 85%
417, - 827.
     The ratio of equipment to total investment varies consider-
ably on an individual foundry basis.  The wide variance in the
range of equipment cost as a percent of total investment is
caused by several factors.  The data represent installations at
many foundries which have many different requirements.  Some
foundries had available space for the control equipment while
others required some plant modifications to install the equipment.
The age of.the foundry affects the cost.  In some new foundries,
the pollution control equipment was designed as an integral part
of the facility, while in old foundries, additional costs must
be incurred for adaptation of facilities.
     These factors and others, as reviewed in Exhibit VIII-1,
represent unique differences between one foundry and another.
The differences affect the total investment cost, as represented
by the ranges given in the previous table.
     The major factor that influences capital cost is the type
of melting equipment.  The complexity of control systems is
                                                                                                 A T KE«iRVFV & ro.MP*VV

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                                                      VIII - 8

 greatest  for  the cupola, moderate for the electric arc, and
 least  for induction melting.

 Cupola Melting
     Air  pollution capital costs are most varied for this method
 of melting, and control solutions encompass a wide variety of
 collector designs.  Often, the collector type will determine
 the required  system components.  Separate studies were made of
 each of the four major control methods.   The factors that have
 the greatest  influence on the investment costs include those
 listed as  follows:
           1.  Number of Cupolas Served on a Single System.
           2.  Materials of Construction  - Corrosion is a  major
 problem in cleaning cupola gases by wet  methods.   Temperature
 is another major factor.  Service factors influence the selection
 of materials  of construction.  Investment costs  will vary signifi-
 cantly when the unit is constructed of corrosion-resistant  metals
 such as stainless steel or when the ductwork is  refractory  lined.
           3.  Water Supply and Solids Disposal -  Investment in-
 creases for wet systems when drain water is clarified in  a  separate
 settling tank, chemically treated, and recirculated by pumps  back
 to the collector.  These costs are obviously less  for systems
 using dry  collection methods.
           4.  Erection Costs - Costs vary greatly  with prevailing
 labor  rates.  In addition,  the location  of the control system,
whether on a new or existing site, plant arrangement,  and special
 rigging required, will affect costs.
                 A T KEARNEY & COMP\XY
                                                        VIII - 9

Electric
  Arc Melting
     A typical air pollution control  system  for  thi«  method of
melting consists of a local exhaust hood  on,  or  at, the furnace
roof, duct connections from the hood  to the  collector,  and n
fabric filter collector.  The factors which  influence the  major
components of an electric arc control installation  include the
following-
          1.  Exhaust Hood - The exhaust  hood will  vary with the
diameter of the furnace.  Also influencing costs are  the problems
'-~f .attaching or supporting the hood to the furnace  structure and
the ease of providing a suitable fixed exhaust point  that  will
permit the furnace roof and hood to swing for charging and tilt
for slagging and pouring.
          2.  Duct Connections - The cost of  ducts  will vary
with the size of the ducts, which are a function of exhaust volumes,
the length of duct run and the amount of  interference encountered.
          3.  Dust Collector - These costs are essentially a
function of exhaust volume.  The cost of  power supply for  col-
lector motors depends upon the collector  location and the  plant
power system.
          4.  Installation - Erection costs  vary with prevailing
labor rates, and problems of adapting to  existing conditions.
     Factors which contribute to cost variations are  summarized
in Exhibit VIII-1.
                                                                                                         * P V r V A- r- o V

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                                                      VIII - 10

 RELATION OF CAPITAL COSTS
   OF CONTROL SYSTEMS TO
   DESIGN VARIABLES	
      A number of design and operating variables are related to
 the  total cost of emission control systems.  These include melt
 rate of the furnace, pressure drop of the system, blast volume
 in standard CFM and gas volume throughput in actual CFM.  A
 computerized multiple regression analysis of the collected data
 has  confirmed that total costs varied most directly with actual
 gas  volume throughput.
      The  greatest differentiation in capital costs due to outlet
 dust  loading existed with wet scrubbers, for low energy systems,
 under 30-inch static pressure drop, and high energy systems, over
 30-inch static  pressure drop.  The costs of these two categories
 have  been  considered separately.
 Cupola
  Melting
      The total investment costs of high and low energy wet
 scrubbers, mechanical collectors, and fabric filters vary directly
 with  gas volume throughput in actual cubic feet per minute.   Invest-
ment  cost equations were obtained by multiple regression analysis,
 in which the equations obtained were the best approximation of
 total investment costs from the available data.  The investment
cost  equations for pollution control equipment  installed on
cupolas are presented in Exhibit VIII-2.  The column in Exhibit
VIII-2 entitled "Limits of Observation" gives the ranges of gas
volumes for which each equation.is validfr -
                 A T KEARNEY * COMPtNY Ivr
                                                                                                                                       VIII -  11
      As  shown in this exhibit,  excellent correlations were ob-
 tained with  high energy wet  scrubbers and fabric filters.  A
 perfect  correlation coefficient is 1.0.   Although the correlation
 coefficients for low energy  wet scrubbers and mechanical collectors
 were  lower,  they were considered to be extremely good.  Graphs
 of  each  equation are plotted in Exhibits VIII-3 through VIII-5.
 The range shown  on  each graph represents the standard deviation
 of  the statistical  analysis.

      The total investment curves all relate total investment?
 costs in 1969 dollars  to gas  volume throughput.   Gas volume
 throughput is related  to cupola operating condition* and—£unaee-
 design.  The significant factors which influence gas volume in a
 cupola are the following:
          -  Blast volume.
          - Size of  charging  door.
          - Method of cooling exhausted  ga-ses. •
          - Location of exhaust  gas take-off.
          - Gas temperature at  the  collector and  fts~exhatzstez*.-
     Blast volume is a function of the oxygen needed  to burn  the
coke.  Metal to coke ratios can be-increased- to produce-higher.
melt rates by preheating the blast air, by oxygen enrichment -of•
the blast-air, and by the -us* of-& snpplemeanT fuel.  Houupgt,~
in present-day practice with an open charging -door and wtefr^gas
take-off above the door, the variation in- blast volume -caaecd by -
these factors will become a less significant factor in the total
gas throughput handled by the control system than the amount of
infiltrated air drawn in through the charging door.
                 A T KEARNEY & COMPANY Ivc

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                                                      VIII - 12
     Charging door openings  require  an  inward flow of air to
confine cupola gases  and  contaminants.  Many designers of air
pollution abatement equipment  specify an indraft based upon 300
FPM through the door  opening,  which  results in significant addi-
tional exhaust volumes that  must  be  handled by the exhauster and
collector.  Even such volumes  are subject  to wide variations where
charge door openings  are  exposed  to  aspirating crosswinds.
Charge door openings  are  determined  by  the method of charging and
the size of charging  equipment,  and  consequently may have little
relation to melting rate.  The effect of air infiltration may
increase gas volumes  to as much as 2007. where gas take-off is
above the charge door.
     Hot gas in the cupola stack must be cooled to safe  tempera-
tures for the control equipment and exhauster.  The degree of
cooling will differ with the type of system  but the exhaust gas
is normally cooled down to about 500° F for  mechanical  or glass
fabric collectors and below 200° F for  wet scrubbers and synthetic
fabric collectors.  The usual methods of cooling  are by water
sprays or air cooled ducts.  However, cooling  of  gases  by use  of
water  from  the high temperatures in the cupola stack introduces
another  significant gas  volume,  that of the  water vapor generated.
Water  vapor can increase  the  total gas volume  handled  by the  con-
 trol  equipment by 20%  to 357..
      The location of  the gas  take-off  also contributes to the
 overall  cost of the control system.  The  placement of  the take-
off ,b»low the  charge  door reduces the  total gas volume handled

                  A T KFM^r^ & COMPANY l^r
                                                      VIII  -  13

 since  indraft  air is at a minimum.  The cost for control equipment
 for  any  given  type of control system is also subject to a  number
 of other factors  that have less correlation with melting rate than
 the  gas  volume.

     Exhibits  VIII-6 and  VIII-7 give the approximate melt  rates
 and  gas  volumes for lined and unlined cupolas.   The increase in
 gas  volume due to a gas take-off above the charge door is  quite
 apparent when  compared to a  below the charge door take-off.
 Exhibit  VIII-8 presents a single comparison of  gas volumes for
 gas  take-offs  above the charge door  and below the charge door for
 a lined cupola.

     Operating a  cupola with an open charge door with an above
 the  door gas take-off  results  in a greater total gas volume.
 The  cost of the control equipment  is then based upon this higher
 gas  volume.  Efforts  to reduce the total gas volume have been
 successful in several  ways,  as described in the following list:
          1.  Providing doors  to partially seal the charge open-
 ing  except during  the  charging period.
          2.  Reducing the charge  opening through the use of  a
vibrating feeder  instead  of  a  bottom drop or skip bucket charger.
          3.  Enclosing the  skip hoist  to eliminate the wind
effect and reduce  the  net open area.
          It.  Exhausting  the cupola  gases  from  below the charging
door level.
          5.   Using a  top charge double  door design.
                 A T KFARNTY gt roMI'\» \

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                                                      VIII - 14
     The amount of water  vapor  in  the  exhaust gas can be reduced
by use of indirect heat exchangers which use the heat in the exhaust
gas for heating the blast air.   With a below the door take-off,
some wet collector systems quench  the  gases without burning off
the CO.  This results in  exhaust gas temperatures of 400° F-700° F
instead of the more usual 1500° F  found with afterburning, and
also results in a corresponding reduction  in the volume of water
vapor produced.
     The total investment costs can be approximated by first
determining the total gas volume generated from Exhibits VIII-6
and VIII-7 and applying this  volume to Exhibits VIII-3 through
VIII-5 for the cost of the specific system type.  However, for
ease of interpretation, Exhibits VIII-9 through VIII-14 have
been prepared to relate installation costs for high and low energy
wet scrubbers and for fabric  filters directly to melting rate
of cupolas in tons per hour.  The  melting  rates were based on an
average metal-coke ratio  of 8:1.  Wet  cap  installations are
directly related to cupola diameter with relatively little
relationship to melting rates or gss flow. Total investment
costs for wet caps as a  function of cupola size are given in
Exhibit VIII-15.
Wet Scrubber Efficiency-
  Pressure Drop Relationship
     The wet scrubber curves have  been separated  into high
energy--over 30-inch pressure drop--and low energy—under 30-
inch pressure drop.  The  relative  effectiveness of  each is shown
in Exhibit VII-21.  High  energy scrubbers  on cupolas are up to

                 A T KTMISFY  «. COMPANY  i^~
                                                       VIII - 15

six times more effective than low energy systems, with n tvpicnl
outlet loading of 0.05 gr/SCF for 30-inch to 70-inch pressure
drop systems compared to 0.3 gr/SCF for systems under 30-inch
pressure drop.
     The degree of gas cleaning obtained at various pressure
drops is illustrated in Exhibit VII-28.  Wet scrubber efficiencies
in capturing  particles exceeding  1 micron in size  are 90%  or  more
for pressure  drops of 10 inches and above.  At  30-inch  pressure
drop  the efficiency exceeds  99% for particles of  1 micron  and
larger.  However,  for fine particle sizes,  in the  range of 0.2
micron  and  below,  a  30-inch  pressure  drop  system is only 957.
efficient.
      The overall collection efficiency is  determined by the par-
 ticle size  distribution in the effluent gas and the ability to
 capture these particles.   For a constant pressure drop, a scrub-
 ber has a different collection efficiency for each particle size.
 The overall efficiency is the weighted sum of efficiencies for
 each particle size.
      Exhibit VIII-16 has been derived as a theoretical  presenta-
 tion of overall collection efficiencies of wet scrubbers  at  various
 pressure drops.  This was done for a typical particle  size distri-
 bution and is based upon data found in the available literature.
 As shown in  the exhibit, the efficiencies in percent of weight
 collected  range from 95.4% at 5-inch pressure  drop to  99.8%  at 60-
 inch pressure drop.  The results obtained are  theoretical and  not
                   A T KEARNEY Sc COMPNVY 1-.

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                                                     VIII - 16
representative of actual  efficiencies which may be obtained at
these pressure drops.   However,  the  exhibit does illustrate the
trends in increased collection efficiency  at increased pressure
drops.

     Increased collection efficiencies due to higher pressure
drops result in a decreased outlet loading.  The amount of the
outlet loading or discharge is influenced  by local air pollution
codes.  Many codes provide for a maximum allowable discharge.
     A plot of the outlet loading versus pressure drop for found-
ries for which data were  available is given in Exhibit VIII-17.
The outlet loading is  expressed  in pounds/ton which factors the
melt rate into the total  allowable discharge of pounds/hour
expressed in process weight tables of many air pollution codes.
     This exhibit illustrates the expected increase in pressure
drop required to reduce outlet loading.  An approximation can
easily be made to determine the  energy necessary to satisfy the
maximum allowable discharge for  a foundry  for those codes which
utilize process weight tables.   The  Los Angeles County Code, for
example, limits the maximum discharge to 10 pounds/hour for a
process weight of 10,000  pounds/hour (5 tons/hour).  The result-
ing outlet loading is  2 pounds/ton,  and from Exhibit VIII-17
the pressure drop necessary to satisfy this condition is 30
inches.
Electric Arc
  Melting
     Although the electric arc furnace is  used in the iron foundry

                  A.T  KEARNEY & COMPANY. IMC
                                                        VIII -  17

for both melting and for holding, the economic analysis has been
directed only at the melting application.   The reason for this is
that only a few holding furnaces have been  equipped with emissions
control systems because the level of emissions for holding only
is relatively low when compared with melting.   The economic
analysis was also limited to fabric filter  collectors on arc
furnaces, again because only a feu installations  have been made
using other methods.
     Fabric filter installations on electric  arc  furnaces have
been related to the diameter of the furnace,  rather than the tons
per hour melted.  Exhaust volume and furnace  diameter relation-
ships approximate the figures in the table  below  and in Exhibit
VIII-18.
         Exhaust Volumes for Electric Arc Furnaces
ROOf
Diameter
6 feet
8 feet
10 feet
12 feet
14 feet
CFM
Local Hood
20 ,000
26,000
30,000
33.000
36,000
CFM
Canopy Hood
55,000
70,000
90,000
115,000
150,000
     Fabric filters can be of the  intermittently cleaned,
single section design, or the compartmented,  continuous duty
design.  When each melting furnace has  its own fabric filter, the
collector can be stopped and serviced at the  end of each melting
cycle.  For multiple furnaces controlled by a single collector
                  A T KEM*VFY fie rriMfivv i.

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                                                      VIII -  18

and for large exhaust volumes,  the continuous  duty  desLgn  is
usual.  On this basis, cost estimates could be approximated as
shown in the tabulation below.
                   Approximate Installed Cost,
                     S/ACFM for Electric Arc

Roof
Diameter
6 feet
8 feet
10 feet
12 feet
U feet
Local
Intermittent
Operation
$2.10 -
1.90
1.85
1.85
l.BO
Hood
Continuous
Service
$2.50
2.50
2.35
2.30
2.25
Remote Canopy Hood
Intermittent
Operation
$1.25
1.25
1.25
1.25
1.25
Continuous
Service
$1.85
1.75
1.70
1.60
1.60
 Exhibit VIII-19 gives the approximate total installed cost of
 fabric filter collectors on electric arc furnaces.  This cost has
 been  related to furnace size and has also been converted to melt-
 ing rates usually associated with various furnace diameters.

 Other Melting
   Methods
      Induction melting  furnjces, as well as induction holding
 units, have  only rarely been equipped with emission control sys-
 tems. This  is also  true for reverberatory methods of melting.
 For this  reason, information has been lacking regarding costs of
 installations on this type of  equipment.  Therefore, data on
 costs have  not been  prepared for this study for these types of
 installations.   However, the cost of induction melting will be
 discussed in a  later section dealing with melting department
 costs.
                  A T KEARNEY & COM HANY
                                                       VIII - 19

OPERATING COSTS OF
  CONTROL SYSTEMS
     A comparison of the impact of operating costs has been made
for wet scrubbers and fabric filters.  These were the more popu-
lar and commonly used types of control systems observed  on found-
ry melting equipment.

     The annual operating costs associated with  air  pollution
abatement equipment are comprised of several components,  includ-
ing the following:
          - Fixed charges
          - Maintenance
          - Operating costs
          - Water treatment
          - Depreciation
     Fixed charges are calculated on the  basis of total  invest-
ment cost.  A  rate of 13% per year has been used to  account  for
interest, insurance and taxes.
     Maintenance includes labor costs and routine replacement
costs, such as bags in a fabric filter.   Maintenance expenditures
are not necessarily uniform from year to  year and will  increase
after  the passage of time.  New equipment may require little or
no maintenance but maintenance requirements will generally in-
crease as the  system grows older.
     Data collected have Indicated that an annual expenditure of
four to five percent of the original equipment cost  for  wet
scrubbers provides an adequate amount for good maintenance.   In
                                                                                              A T KEARNEY & COMPANY  IKC

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                                                      VIII - 20
                                                                                                                               VIII  - 21
the case of fabric filters,  the maintenance  figure was estimated
to be about five percent per annum of the  original equipment cost.
These percentages were reduced to about  two  percent  for  smaller
foundries which melted less  than 1,000 hours per  year, with
lower pollution control system utilization.
     In addition, a separate amount was  added for bag replace-
ment.  This vas based on a 100X bag replacement each year  for
foundries with continuous melting and reduced to  a 100%  bag
replacement each third year  for foundries  with intermittent
melting.  The replacement cost was $10 per bag.   Manufacturers
of fabric bags have indicated that In a  large number of  cases,
the replacement of filter bags has been  less frequent than once
a year, with bags sometimes  lasting five years or more.
     The number of filter bags required  for  cupolas  and  electric
arc furnaces with local hoods was calculated for  an  air  to cloth
ratio of two to one.  For electric arc furnaces with a canopy
hood, the air to cloth ratio used was four to one.
     The maintenance costs used in the analysis do not include
costs associated with equipment modifications after  installation.
A few foundries visited reported a large expenditure for changes
early In the life of the control equipment,  and some reported a
cost for modifications after several years.
     A disproportionate Increase in maintenance costs may  possibly
occur in systems with large pressure drops.   The  increased horse-
power and system requirements due to greater pressure drops may
create conditions that accelerate the maintenance  costs.   This
has not been determined for this study.

     Operating costs include electrical power and  makeup  water.
For wet scrubbers, these are the major costs.  Electrical power
is required for the fans and pumps.  Power requirements vary with
the equipment size and pressure drop.  The total power require-
ments for high and low energy scrubbers are 15 HP/1,000 ACFM and
S HP/1,000 ACFM respectively.  These formed the basis for cal-
culating operating costs for scrubbers.  Power requirements  for
fabric filters were based upon 2 HP/1,000 ACFM.

     Requirements for makeup water in gas cooling  and scrubbing
are related to equipment size.  The data collected have Indicated
a correlation of makeup water to equipment size for wet scrubbers
at about 2 gallons/1,000 ACF.

     Electrical energy and demand costs were calculated at
rates based upon the prevailing power rates in the Midwest for
process industries.   Water costs were also based upon rates  in
Large midwestern cities.  The water cost used in the analysis  is
$.275/1,000 gallons.

     Many foundries  utilize afterburners in cupolas to insure
:he ignition of the  top gases.  The combustion of  the top gases
burns off any carbonaceous matter present in the exhaust gases.
Dther foundries rely on afterburners to specifically burn off
:arbonaceous material.   A review of the capacities of the burners
jtllized indicates that the selection is somewhat independent  of
                  A. T. KEARNEY ft COMPANY INC
                                                                                         A T KEARNEY » COMPANY. INC

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                                                       VIII  -  22
cupola size or melt rate and is rather arbitrary.   Several
foundries had afterburners of such size and capacity  to provide
substantially more energy than required for complete  combustion.
The use of afterburners has not been considered  in the  total
annual costs.  However, an approximate cost per  operating hour for
each million BTU's of gas burned Is $.60,  based  on midwestern
gas costs.
     Water treatment includes the chemical treatment  to the
scrubber water in the sludge tank.  This includes  flocculation
and neutralization.  Foundries requiring water treatment indi-
cated a range of $.03 to $.085 per ton of iron for chemical
costs.  For the purpose of this analysis,  $.05 per ton  was  used.

     Depreciation was calculated on a straight line method  based
upon total investment.  The useful life of control equipment
was taken as 10 years.  In several foundries,  however,  the  equip-
ment was found to have a longer service life,  but  rapid advances
in technology and more stringent local codes may tend to accelerate
technical obsolescence of these older units.
     The annual calculations of cost for wet scrubbers  are  based
upon four levels of foundry operation:  500, 1,000, 2,000 and
4,000 hours/year.  It is reported that in large  foundries operat-
ing 4,000 hours or more per year, rather than  shutting  down
cupolas during "off" shifts and over a weekend,  they  may be  run
at a reduced level.  This results in additional  operating hours
for the control equipment, which may cause a slight increase in
the cost estimates.
                                                      VIII - 23

     Exhibits VIII-20 and VIII-21 present approximate total
annual costs for high and low energy scrubbers on cupolas and are
presented for operating levels of 500, 1,000, 2,000 and 4,000
hours/year.   The curves relate total dollar costs versus gas
volume for a single system pressure drop.  As the pressure drop
of a control system increases, the power requirements will in-
crease.  A doubling of the pressure drop, for example,  results
in a doubling of the required horsepower.
     Exhibit VIII-22 presents the  relative change in total .
annual costs as  pressure  drop increases.  These  were calculated
for  each operating level.  It becomes  readily apparent  from this
exhibit how a change in  pressure drop affects wet  scrubber annual
costs.
      If  pressure drop increases from 30 to 40 inches for a 5-ton-
 per-hour melt rate and a 500-hour/year operating level, the in-
 crease in annual costs would be from an index of 1 to about 1.04
 or a 4* rise.  The corresponding increase in theoretical removal
 efficiency, from Exhibit VIII-16, would be a rise of 0.1%.  A
 larger foundry operating at 4,000 hours per year and at  30-ton-
 per-hour melt rate would experience an annual cost  increase of
 approximately 6%  for a pressure drop  increase from  40  to 50 inches.
 The increase removal efficiency for this example would be  about
 0.1%.
      The detailed information to make up Exhibit VIII-22 has
 been plotted as total annual costs in dollars,  versus  gas  volume
 for a family of pressure drop curves.   This  was done for each
                 A  T KEARNEY & COMPANY INC
                                                                                            A T KEARNEY «> <
                                                                                                                     INC

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                                                     VIII - 24

 operating l&vel.   These  curves  are  presented in the detail
 economic cost  curves  in  Appendix  D.

     Tn the case of fabric filters,  it was  assumed  that gas
cooling is accomplished by air and not by a water quench.  This
removes the need for makeup water and water treatment.  The  total
annual operating costs for baghouse  installations on cupolas are
illustrated in Exhibit VIII-23.   These costs are presented for
4,000 hrvirs/year, 2,000 hours/year and 1,000 hours/year.  The
comparable costs for fabric filter installations on electric arc
furnaces are given in Exhibit VIII-24 for canopy hood  and local
hood exhausts.  Operating levels of 4,000 hours/year,  2,000
hours/year and 1,000 hours/year are  also presented.

RELATION OF OPERATING
  COSTS JF CONTROL SYSTEMS
  TO DESIGN VARIABLES
     The annual costs of wet scrubbers and  fabric filter
collector;; on cupolas, as presented  in Exhibits VIII-20 through
VIII-23. £.re all based on gas volume throughput expressed in
ACFM.  acwever, there is a relationship between gas volume and
melt raci for different metal to coke ratios.  Exhibits VIII-6
and VIi:-~ gave this relationship for lined and unlined cupolas.

     By 'j-ambining Exhibits VIII-6 and VIII-7 with Exhibits
VIII-20  rrroueh VIII-23, the annual  cost of wet scrubbers and
fabric f.trers on cupolas are expressed as  a function  of melt
rate for i variety of metal to coke  ratios.  Also included are
                 A T KF.ARNI V A € <>P>
                                                       VIII - 25

 comparative  costs  for gas  take-offs above and below the charge
 door.

     The  curves  of annual  cost versus melt rate are presented in
 Appendix  D.   Sets  of  curves  are given for operations of 4,000
 hours/year,  2,000  hours/year and 1,000 hours/year for low and
 high energy  wet  scrubbers  on cupolas and for fabric filters on
 cupolas.   Both lined  and unlined cupolas are considered.

     As expected,  installations with gas take-offs 'above the
 charge door  have higher annual costs than similar control equip-
 ment installations  but with  gas take-offs below the charge door.
     The  total annual costs  for scrubbers and fabric filters on
 cupolas,  as  illustrated in Appendix D,  have  also been modified
 to present the costs  on a  basis of  cost per  ton of melt.  Esti-
 mates of  cost per ton of melt  are given in Appendix D for the
 various operating conditions and operating hours discussed
 earlier.

     A summary of the cost-per-ton  curves, comparing 4,000-hour/
 year, 2,000-hour/year and  1,000-hour/year levels of operation,
 are given in Exhibits VIII-25  through VIII-30.   These summary
 curves are given for  low energy and  high energy wet scrubbers
 and fabric filters on cupolas  for a  constant  metal to coke ratio.
     From these exhibits,  it becomes apparent that the cost  per
 ton of melt rises rapidly as the size of the  foundry operation
decreases.  The cost increases,  for example,  for a high  energy
scrubber from S3/ton at a 4,000-hour year to  over  $8/ton at a
                                                                                            A T KhARMEY * COMP*NY I-

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                                                     VIII  -  26
                                                                                                                                 VIII - 27
at a 1,000-hour year.   Lower levels  of  operation would  exceed
$12/con or more.

EFFECT OF EMISSIONS
  CONTROL ON CAPITAL AND
  OPERATING COSTS IN MODEL
  FOUNDRIES	
Model Foundry
  Development
     The effect of adding emission controls,  on  the  capital  and
the operating costs of the melting department in the iron foundry,
was developed for a variety of different melting methods,
different sizes of foundry, and different Levels of  operation.
The various alternates which were evaluated are  described below.
     (a)  Melting Systems
          Studied	
          1.  Cupola melting, cold blast, lined,  below door gas
take-off, with unheated forehearth, with fabric filter emission
control.
          2.  Cupola melting, hot blast, unlined, water-cooled,
below door gas take-off, using channel-type induction holding
furnace, with a high energy wet scrubber emission control system
on the cupola.
          3.  Arc furnace melting, using channel-type induction
holding furnaces, and provided with a fabric filter emission
control system on the arc furnace.
          4.  Induction furnace melting, crucible type, no
holding furnace, using scrap preheaters, and with afterburners
provided in the preheater stack for emission control.
     (b)  Sizes of Foundries
          Studied	
     Sizes of foundries in terms of tons per hour melting capacity
were selected at levels of 5, 15, 30, and 50.  The range included
in these melting rates covers most of the foundries operating in
this country with the exception of a few very large captive plants
and some very small operations.

     (c)  Levels of Operation
          Studied	
     The operating levels included in the study, in terms of hours
per year of melting operation, were selected as 500,  1,000, 2,000,
and 4,000.  These correspond respectively to melting  2  hours per
day, 4 hours per day, 8 hours per day, and  16 hours per day.
     Because of practical operating limitations on some types  of
melting equipment, not all melting methods  were analyzed at all
melt rates and operating  levels.
                 A T KFARS'EY * COMPANY lie
                                                                                             A T KEARNEY & COMPANY I •« o

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                                                      VIII - 28
 Qualifications  Regarding
   Model  Foundry Design Data
      The intent of  the model foundry economic development in
 this  study was  to provide comparative figures relating the capital
 and operating costs of melting departments of foundries of varying
 sizes and rates of operation, and utilizing different methods of
 melting, to  the requirements and costs of emission control.  The
 actual design and operating data were based on commonly utilized
 equipment and raw materials, for the foundry sizes and rates of
 operation which were selected,  and thus represent average con-
 ditions  rather  than actual operating foundry cases.   It was recog-
 nized th»»t further refinement of these design and operating data
vould probably  result in cost figures which would more closely
 approximate actual costs in many foundries.   However,  the figures
which were developed are believed to be reasonably representative
 and are useful for comparative  purposes.
Equipment and
  Building Specifications
     The model foundry melting  departments  which  were  developed
 for this economic analysis were intended to represent  typical
conditions for the methods of melting and the sizes of foundries
which were evaluated.   For purposes  of comparison,  similar facil-
ities for auxiliary operations  and services  were  used  in each
case.   The only exception  was that the smallest size melting
department did not contain a full complement of auxiliary items,
in accordance with usual design practice in  these  small  instal-
lations.
                 it. T KEARNEY St COM PAN-.  I »,
                                                      VIII •• 29

     The melting department was considered to encompass  the
facilities and operations from raw materials receiving through
molten iron holding.  This included raw material  unloading,
scrapyard, charge makeup, charging, melting, scrap preparation,
emissions collection, slag handling, water system, holding
furnace or forehearth, buildings and services.

      (a)  Melting
     	Equipment
     The melting systems covered were  those in  principal use:
cold blast, lined cupola; hot blast, unlined water-cooled cupola;
electric arc  furnace; and coreless  induction furnace.  Channel
induction holding furnaces were used for  the water-cooled cupola
and the electric arc  installations, unheated forehearth  was
used  for the  lined  cupola, and no holding furnace was used for
the induction furnaces.  High energy wet  scrubbers were  applied
to unlined  cupolas, fabric  filters  to  the arc  furnaces,  and a
minimum afterburning system  on  the  scrap  preheater for the induc-
tion  furnaces.  An  alternate of  fabric filter  collectors was also
considered  for the  lined cupolas.

      (b)   Emission  Control
      	Equipment
      Emission control equipment selected was based on those
 items normally used to control emissions for a particular melting
 method and includes basic as well as auxiliary equipment.
      Melting  alternate Ho. 2 is equipped with a wet
 scrubber emission control system.  A wet scrubber's capability
 to capture particulate matter is a function of the amount of

                  A T KEARNEY &  COMPANY. IMC

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                                                       VIII  -  30

energy expended in the system which is measured by  pressure
drop.   The higher the pressure drop,  the greater  the  amount  of
particulate matter collected and the higher  the capital and
operating cost for the system.
     Wet scrubber designs were selected  that would  satisfy the
more stringent air pollution codes.  For the purpose  of this
study, the air pollution code for Los Angeles County  was selected
as a basis for determining wet scrubber  efficiency  cost require-
ments.
     The Los Angeles Code establishes a  maximum allowable dis-
charge per hour based upon process rates.    Exhibit VIII-17
indicates the minimum pressure drop required to capture various
emission discharge levels.  From this information,  it is possible
to determine the pressure drops required to satisfy the Los
 Angeles Code  according to melting rates established  for  this
 study.   These figures are shown below:
      Melt Rate, Ton/Hour            5        15     30       50
      L.A. Code Maximum Discharge
        (pounds/hour)
10
        22.22   40
                        40
      Outlet Loading (pounds/ton)
                                             1.48
                                                     1.33
                                                              .8
      Wet Scrubber Pressure Drop
        Required to Meet L.A. Code  30 in.   40 in.   45  in.   60  in.
      Melting alternate Nos. 1 and 3 are equipped with fabric
 filters.  Since fabric filters collect nearly 100% of all  par-
 ticulates and therefore meet existing air pollution codes  in
 analysis of their relative capabilities and efficiencies  for
                                                       VIII -  31

this investigation uas not required.  The only point that needs
clarification is that the fabric filters selected for the arc
furnaces are equipped with a local hood rather than a canopy type.

     (c)  Buildings
     A determination was made of the appropriate amount of
building space which would be required to melt iron based on  the
five alternates selected.  This included provision for  all  aux-
iliary building requirements such as transformers and similar
equipment.  No provision was made for cost of  land.

Capital Costs
     This consists  of all melting, holding,  auxiliary equipment
and buildings as well as emission control  systems required  for
a  typical melting department.

     Melting and holding equipment capital costs are current
figures obtained from equipment suppliers  and  data  from foundry
installations.  Costs of equipment installations including
foundations and services, such as engineering, have  been based on
percentages of original new  equipment cost.   Building costs per
square  foot are based on midwestern construction  figures and
vary according to the type of melting method employed.   Emission
control equipment capital costs were obtained  from  information
previously  developed which is shown in  Exhibits  VIII-3, VIII-4,
VIII-18 and VIII-19.
     Exhibit VIII-31 summarizes capital  costs  required  to install
melting departments for  the  various alternate  melting methods
                   A T KEARNEY & COMPANY. INC
                                                                                            A T KF^PS-FY* <- o V r> vv

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                                                       VIII - 32
                                                                                                                                      VIII - 33
and foundry sizes which were considered.   The details of these
capital costs are given in estimates in Appendix D.   That portion
of total capital costs accounted for by emission control ranges
from 0.5% to 19.41 depending on the production and operating
conditions involved.  More specifically,  these ratios vary by
the conditions defined as shown in the table.

                         Percent of Emission Control Tost
                   Hi 1C Inn <'o«t« - EVr Tno i'f I rnii
Alternate Number Lowest
1 11. 61
2 12.11
3 5.91
* O.S1
Operating
Costs
Melt Rate Operating
Tons/Hour Hours Highest
5 2.000 19.47.
IS 2.000 16. 3'/.
4.000
50 2,000 12. 11.
4,000
30 2,000 0.6S
50 4,000
Melt Rate
Tons /Hour
SO
50
5
S
IS
Operating
Hours
2.000
A, 000
2,000
4,000
SOO
1,000
2.000
WO
1.000
2.000
4.10(1
     These costs were developed per ton of hot metal at the
 spout  of  the melting or holding furnace and include direct
 materials, all conversion costs and emission control equipment
 operating costs related to the various methods established.

     Exhibit VIII-32 gives a summary of total operating costs
 per ton required to produce iron based on the alternates under
 investigation.  These figures are briefly summarized in the
 table  on  the following page.
'itfn'/II.'iur
KiniK'r lu r W.ir
1
2
J
*
,,
son
5IJ7

.MI
182
1 .000 J.OOO 4.000
•IlOJ S TO
81 S7<1
lij 106
128 101
l-i
i .onii
$ 88

125
93
J.ono 'i
S!"
Jh
lJh
82
.{Hill
s;-.
UK
no
74
10
J.OMO 4.IIOl>
•US f(."
71 • >
0" 7t,
80 71
MI
1 «lOi» 'Mil
,;i .,-
i-
-.
i« i •>
     (a)  Direct Material
     	Costs	
     The metal to be produced was selected  as  gray cast iron hav-
ing 35,000 PSI tensile strength which  is  a  grade commonly produced.
To provide a meaningful comparison,  all alternatives were studied
on the same basis.  The direct materials  used  for the various
melting furnaces were selected as representative charge propor-
tions which would provide  the desired  grade of iron.  Prices of
direct materials are based on published  quoted prices for the
second quarter of 1970, Chicago area.   For  both the cold blast and
hot blast cupola melting methods, a metal to coke ratio of 8 to
1 has been used in  the  study.  The  direct material costs per
ton for the five melting methods  are shown in the table below.
           Melting Method
     Lined Cupola - Cold Blast
     Unlined Cupola - Hot  Blast
     Electric Arc
     Induction Coreless Type
Direct Materials  S/Ton
        $51.09
         47.14
         44.69
         47.06
These direct material costs have been applied to all melting
rates and all production  levels studied.   No attempt was made
                 A.T.KEARNEY & COMPANY INC
                                                                                                A T KEARNEY 8> COMPANY. Ixc

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                                                        VIII - 34
                                                                                                                                       VIII - 35
                                                                                                          ion Costs - IVr Toil of L run
 to  evaluate  the  effect  on  scrap prices  of  volume  buying  by  the
 larger foundries which  would operate  2,000 or 4,000 hours  per
 year.   Also,  the type of casting  being  produced affects  the
 yield  and the available percentage  of casting returns.   Approx-
 imately one-third of the metallics  were assumed to be  r.-turns.

     The details of the direct material proportions and  per ton
 costs  are shown  in Appendix D.

      (b)  Conversion
     	Costs	
     Conversion  costs consist of  all  direct and indirect labor,
 supervision,  supplies,  maintenance, depreciation, capital  charges,
 utilities and allocated expense required for charge makeup,
->_lic,..£i-ng, scrap  handling and preparation if required,  melting
 and holding.   Allocated expense consists of that  portion of
 other  foundry functions such as general management, quality
 control and administration which  are  necessary to operate a
 foundry melting department.
      Conversion costs,  calculated for each of the alternatives,
 were based on operating data obtained from foundries.   The data
 were modified as required  to fit  the  particular operating con-
 dition.
      Conversion costs  per ton for  the various conditions in-
 vestigated are  shown in the  table on the  following page.
AllrrnntL Opi-rnrinR.
1
2
3
4

S 66
_
144
144
1 ,000
$45
-
85
•b
2.000
535
38
55
S6
4.000
.
$29
-
-
1 .11(10
$33
-
7S
57
2 .0(1(1
S2ft
27
'.8
>8
4 .000
$20
1'P
11
IK
> .11110 '. .0(1(1
$J2 Sid
22 II-
4 1 i«
V. "•
2,0(10 '. ,(l(l(>
JI9 -1^
!•> 1 .
17 •'
10
Conversion cost details are shown in Appendix D.

     (c)  Emission Control
     	Costs	
     This consists of all costs  associated with operating an
emission control  system and includes  capital charges, maintenance,
utilities and  depreciation.
     Emission  control  operating costs were derived from data
previously  developed which are depicted in Exhibits VIII-20,
VIII-23 and VIII-24.
           1.  Alternative costs.  Emission control equipment
 operating costs per ton for the different conditions  investigated
 are shown in the table.
ltolt Uace 	 ]
"

-
4
,10 00 S 6 00 S3 50
3 50 S2 50
22 40 12 10 6 30
46 27 17
15 	 .
1 ,000 2 .000
S4 00 S2 33
2 00
5 '.7 3 27
20 1'
4.000
51 33
1 25
2 13
30 3
?2 33
1 83
2 45
II
4.000
SI 33
1 17
1 60
10
2 ,000 - .010
51 ;n _-' no
1 65 °»
1 <* 1 :=
11 "
                  A T KEARNEY 6t COMPANY l-it-
                                                                                                   A  T  KFM5VFY «c rOMP*VV

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                                                      VIII  -  36
                                                                                                                                     VIII - 37
          That portion of total operating costs  accounted  for
by emission control ranges from 0.1% to 10.6% depending  on the
alternative condition.  More specifically, these ratios  vary by
the conditions established as shown in the table below.
                          Percent of Emission Control  Cost
                             to Total Operating Costs
Alternate
Number
I
2
3
4

Melt Rate
Lowest Tons/Hour
I
1
I
0
2
.si so
.61 SO
.81 50
.11 50
. Wet scrubber
Operating
Hours
4,000
4,000
4,000
2,000
4.000
costs and
Highest
7.97.
3.9%
10.6%
0.37.
Melt Rate Operating
Tons/Hour Hours
5
5
5
5
efficiencies.
soo
2,000
500
500
To properly
evaluate wet scrubber performance for this investigation,  It is
necessary to determine the relationship between costs,  efficien-
cies and pressure drops.  As mentioned previously,  the  Los
Angles County Air Pollution Code formed the basis for wet scrubber
requirements.
          Exhibit VIII-16 indicates  theoretical wet scrubber particu-
late removal efficiencies and corresponding pressure drops for a
typical particle size distribution.   Based on these figures, the
efficiencies developed are presented  below:
     Melt Rate Tons/Hour	5     15      30
Pressure Drop
Particulate Removal
Efficiency
30
96.5%
40
98.9%
45
99.5%
60
99.8%
          An  increase  in  the  pressure drop for each melt rate
would result  in  an  increase in  removal efficiency.  This con-
dition would  also increase wet  scrubber operating cost as shown
in Exhibit VIII-22.  In developing Exhibit VIII-22, a pressure
drop of 30 inches was selected as  an  index.   Curves are  given
for each of the  four operating levels;  i.e.,  500,  1,000,  2,000
and 4,000 hours  per year.
          As shown in Exhibit VIII-22,  a  pressure  drop increase
from 30 to 40 inches would result  in  an increase  in the  wet
scrubber annual  costs index from 1.0  to 1.05  for  the 2,000-hour-
per-year operating condition.  This represents  a  cost increase
of 5%.  Therefore, the 5-ton, 2,000-hour  wet  scrubber operating
cost previously  shown would increase  from $3.50 to $3.71 if  a
40-inch, instead of a 30-inch, pressure drop  scrubber was
selected.
Summary of Capital
  and Operating Costs
                 A T.KEARNEV & COMPANY. INC
     Exhibits VIII-33 through VIII-36 depict  the  relationships
of capital costs to operating costs per  ton for the  various
production and operating conditions investigated.  These  figures
were obtained from Exhibits VIII-31 and  VIII-32.

BENEFITS OF EMISSION
  CONTROL INSTALLATIONS
     The major emphasis of this chapter  has been  directed to-
ward estimating the costs associated with  purchasing,  erecting,
and operating emission control equipment.  In this section,  the
direct and indirect benefits to the foundry for installing
emission control equipment are discussed.
                 A T KEARNEY & COMPANY Ivc

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                                                       VIII  -  38
      During  che  field  interviews for obtaining data, foundries
 were  asked to  identify any benefits they had experienced from
 controlling  air  pollution.   In a vast majority of the cases
 the installations were new, and it was too early for the foundry
 to ascertain if any benefits would accrue.   Several of these
 foundries expressed an anticipated savings  in roof maintenance
 due to less frequent cleaning.

     Roof raaintenanace and gutter cleaning  was  the mosC  fre-
 quent benefit listed.  The reduction in particulars emissions
 also resulted in less frequent cleanup in other areas of the
 plant.  Maintenance and building deterioration  were reduced,
 resulting in less cleaning and painting.  One foundry reduced
 the cleanup required at the air intakes, heater coils,  and
 ductwork.

     Many foundries expressed a direct savings  in plant  main-
 tenance costs.   The reported savings ranged from $600 to
 $5,000 per year.   A large foundry,  producing 30,000 tons per
month, indicated a savings in equipment and building maintenance
 as great as $200,000 per year.  The manpower requirements for
maintenance were reduced.  Where one man was required constantly
at one'tounary  without control equipment, the installation  of
pollution control equipment reduced the manpower needs for
pollution-related maintenance to one man every  four  weeks.
     Other foundries indicated a general improvement in  the in-
 plant environment due to the elimination of cupola gases escap-
 ing at the charge door and dispersing through the plant.  The
                                                        VIII -  39
atmosphere on the charging floor has become clearer and the
generally cleaner foundry atmosphere resulted in better light
conditions.  As a result of the generally healthier working  con-
ditions, employee relations were improved.  Several foundries
indicated that as a by-product of the cleaner foundry environ-
ment, employee complaints and personnel  turnover have been
reduced.  One large foundry reportedly experienced a  savings
of as much as $200,000 per year due  to fewer personnel problems.
     Most foundries located close to residential and  commercial
areas stated that with control equipment, atmospheric conditions
in the neighborhood improved to degrees  that neighbors'  com-
plaints virtually ceased.
     Other benefits attributed to the installation of control
equipment were that potential hazardous  areas of toxic gases
were eliminated and refractory replacement  in cupola  stacks  were
reduced.
     Although no sound economic use  of the  particulate matter
has been stated, many foundries use  the  by-product  for land  fill".
                                                                                               A T KEARNEY fie COMPANY INC

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                                                      VIII  - 40
                     REFERENCES
     1.   County of Los Angeles, California. Air Pollution Con-
trol District,  Rules  and Regulations, Regulation IV,  Prohibitions.
                 A T KEARNEY & COMPANY. INC
IX - TECHNICAL AND ECONOMIC ANALYSIS
      OF POTENTIAL MODIFICATIONS TO
     FOUNDRY PROCESSES AND EQUIPMENT
                                                                                IMPROVEMENT OF
                                                                                  EMISSIONS CONTROL
                                                                                  CAPABILITY	
                                                                                      Three Approaches  are  possible in the effort  to improve
                                                                                foundry emissions  capability  at  a  lower cost:   the modification
                                                                                of emissions producing equipment to reduce emissions, changes in
                                                                                operating practice, and improvement of emissions control equip-
                                                                                ment.   Modification of emissions producing equipment often
                                                                                requires a change  in operating practice.   Because of this
                                                                                condition, potential changes  in  these two areas are discussed
                                                                                together, and improvements  of collecting equipment are discussed
                                                                                separately.
                                                                                      A systems concept must  be  applied to the analysis, par-
                                                                                ticularly with regard to costs.  An increase in scrap metal cost,
                                                                                for example, resulting from a change in quality specifications,
                                                                                or special pretreatment, may  have  an overall cost benefit if
                                                                                a less costly control device  can be used to collect the emissions.

                                                                                      An overview  of industry efforts Coward this  basic problem
                                                                                shows no major technological  breakthrough, but rather an ongoing
                                                                                effort to better existing equipment through improved design and
                                                                                the use of new materials.

                                                                                      Some results of innovative thinking are  apparent such as
                                                                                 the reverse draft, "upside-down cupola," and  a cupola emissions

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                                                     IX - 2
cooling system using a counterflow of a granular material  such
as sand.  The successful operation of these particular  systems
has not yet been proven, although a full-size test of the  new
cupola design is now under way with published results expected
in the near future.
     Due to the proprietary and often confidential nature  of
research and development effort by equipment manufacturers,
detailed information on various projects under way at this time
cannot  be discussed unless public disclosure has already been
made.  The material in  this section  is therefore limited to
 recent  developments not yet fully accepted by the industry,
or  to concepts  advanced by industry  representatives outside the
 equipment manufacturing companies.

 POTENTIAL MODIFICATIONS
  TO FOUNDRY PRACTICES
  AND EMISSIONS PRODUCING
  EQUIPMENT	
      Of all  foundry  operations  causing  emissions  to be released
 to  the  atmosphere in  some  degree,  the melting operation has re-
 ceived  the  greatest  attention from emissions control boards,
 the general public,  foundry operators, and equipment manufac-
 turers.
       The effort to improve collection capability at a lower
 cost has been concentrated on the problem of the  cupola as  the
 source of the greatest amount of particulate matter.   The result
 of these investigations in recent years has been  a number of
 modifications offering at least a partial solution to  the prob-
 lem.
                     r i. r « l> NT"
                                                           IX  -  3

        Other work has been done tn che areas of preheating,
  magnesium treatment for producing ductile iron, pouring  and
  cooling, sand handling and coremaking.
  Potential Modifications
    to Cupolas  and Cupola
    Operations	
        Cupolas and cupola  operations  can be modified in an
  attempt  to achieve two  goals-to  decrease the  cost of emissions
  collection and to decrease  the  quantity  of emissions  requiring
  collection.   With collection equipment and operating  costs
  directly  related  to the amount  of gas to be processed,  a  direct
  approach  to the cost problem is to decrease the gas volumes.
 A regression analysis, described in Section VI, showed  no
 significant relationship between cupola  design factors  and
 emission quantities.  The analysis did,  however, indicate that
 emission would be lessened by modifications to operating
 practices resulting in decreasing  the coke charge and eliminating
 contaminants  from the  charge material.
       (a)   Decrease Stack
            Gas  Volume
       One  method  of decreasing the volume of cupola stack  gas
 is to  limit air infiltration by  reduction of the charging  door
 area.  This requires a change in the charging equipment  since a
 large door  opening is required for the entrance of  drop  bottom,
core bottom, and end or side dump charging buckets.  In place
of buckets, the charge materials can be discharged  into  the CUpola
by chute or oscillating conveyor.  Some concern over possible

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                                                       IX  - 4

charge segregation was expressed when this  modification was
first proposed, but evidence from several systems  now  in opera-
tion shows that the problem is not serious  with  the  lighter
density charges in general use at this time.   Cupolas  up to 48
inches in diameter have been charged successfully  by means of
a chute, and cupolas up to 84 inches in diameter by  means of an
oscillating conveyor, using a standard skip hoist  to raise the
charge materials from the yard level.

      One foundry has recently installed a  new water-cooled
cupola with the charging opening reduced from  a  normal 96
square feet in area to 16 square feet.   Charging equipment
consists of a conventional skip hoist,  and  a 42  inch wide
vibrating feeder.  The feeder is arranged so that  it can be
moved forward into the charge door opening  for charging and
retracted when the material is completely discharged into the
cupola.  Reduction of the door opening has  reduced the in-
spirated air 83% and total gas volume  59%.

      A cost comparison of systems using conventional  and con-
veyor charging methods was prepared to aid  in  final  selection
of equipment.   The analysis included equipment and operating
cost estimates for the two systems furnished with emission
control equipment to limit emissions to 0.15 and 0.05  grains per
standard cubic foot of exhaust gas.  The comparison  shows equip-
ment cost savings of approximately $80,000 using the small
charging door and conveyor charging.  Annual operating cost
savings are about $7,500 for the 0.15 gr/scf system, and $18,500
                 A T KEARNEY & COMPANY I»c.
                                                        IX - 5

 for  the  .05  gr/scf system using the small charging door opening.
 The  system is  reported  as working satisfactorily with no adverse
 effects  due  to charge distribution or segregation.

       Locating the gas  take-off below the top of the charge
 burden is  a  second method of reducing air infiltration and
 thereby  decreasing the  volume of gas to be cleaned.   This method
 requires the use of an  induced draft fan to substitute for the
 stack  effect and is used  on  cupolas with emission, control equip-
ment.  Placing the take-off  approximately 3 feet below the top
of the charge  effectively limits air pulled down through the
burden to  about 10% of  the blast air volume,  independent of the
charging door  area.

      There are two alternative  methods of processing the gas
after  removal  from the  cupola.   In one,  the gas  passes through
a combustion chamber where secondary combustion  occurs with the
assistance of  a gas burner and with only sufficient  air added
to support the combustion.   Combustibles including carbon
monoxide are completely burned,  after which the  gas  is cooled,
cleaned, and discharged to the atmosphere.   For  the  other
alternative,  the gas is immediately cooled,  cleaned,  and dis-
charged back into  the cupola  stack below the  level of the
charging door, where it can  be ignited  by afterburners to remove
the carbon monoxide content,  if  desired.   A portion  of the
cleaned gas,  which contains essentially  no oxygen, is drawn  into
the gas take-off and recycled  through the flooded  disc scrubber.
A certain hazard exists in cooling  the gas  after take-off prior
                                                                                                  A  T  KFM3NFY & COMP'kVV 1 v«-

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                                                      IX - 6

to immediate ignition in a combustion chamber.  The negative
pressure in the take-off enhances  the possibility  of  inward air
leakage through any opening,  and also of drawing air  downward
through the burden, to form an explosive mixture of CO and 02.
Discharge of the cleaned and cooled gas into the cupola  below
the charging door insures against  inspiration of air  through
the charging door, but extra care  must be taken to insure that the
take-off ductwork is airtight when installed.  A good preventive
maintenance program is desirable to insure that it remain so.
      Reduction of charging door size with conveyor or chute
charging and below charge door gas take-off systems are  effective
in reducing the quantity of infiltrated air.  However, they  lend
themselves more readily to new installations than  to  modifica-
tions of existing cupola melting systems.  The expense of
relocating an existing skip loader or charging machine and
possibly altering or installing a  charging floor  for  the feeder
usually offsets the operating cost savings.  Only  if  the exist-
ing cupola is charged by crane or monorail is it  probably
economically feasible.  Installation of a below charge door
take-off on an existing cupola can also be too costly to result
in an early payback.  Lack of space adjacent to the existing
cupola may not permit installation of a combustion chamber  or
cooling device to quickly lower the gas temperature to a safe
level.
      One manufacturer of emissions control equipment has  re-
cently reported on a system with the gas take-off located  opposite
                      « r « P v~ v •• r
                                                       IX - 7

the charging door opening.  The total gas volume, including
inspirated air, is reportedly reduced about 507. by the special
design of the take-off.  The infiltrated air sweeping across
the cupola stack from the door opening to the gas tak«--off acts
as an air curtain preventing escape of the off-gases out the
open charging door or vertically into the upper stack.  This
system, if technically successful, has the advantage of re-
quiring relatively simple and inexpensive alterations to an
existing cupola.  The gas take-off should be somewhat less
expensive at the charging door  level than near  the  top of  the
cupola since it will be  smaller  and require  less  supporting
structure than at the higher elevation.  Furthermore, the  re-
sulting gas volume  requiring cleaning  is independent  of  charge
door  area and whether  the charge door  opening  and cupola top
are open or closed.
       A  fourth technique for  reducing  air  infiltration is pro-
viding doors  for the charging  inlet.   This method has been in
use  for  some  years  with indifferent results, due to mechanical
 and electrical problems with  door operating controls, and with
warping  and lining problems with the doors themselves.   Severe
 operating conditions have inhibited the development of reliable
mechanisms  for opening and closing the doors at the desired
 times.  Furthermore, sudden increases in gas volumes when the
 doors are opened either overload the collection system, or
 require that it be designed for the full open door capacity.
 The result of the first is puffs of incompletely cleaned gases
                                                                                                    A T KEARNEY Sc COMPANY

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                                                       IX - 8

and  of  the second, no savings In Che system cost.

      The problems related to charging doors have resulted in
the  discontinuance of many installations after repeated damage
to the  doors by charging buckets.  The most successful and long-
lived have been those installations with the simplest of
mechanical controls.  In order to permit sufficient air in-
filtration for secondary combustion, doors are either provided
with openings in the bottom half, or are made shorter than the
cupola  door opening.  Installation costs ranging from $1,500 to
$3,500  per cupola have been reported depending upon the cupola
size and type of operating mechanism and control.
      (b)  Decrease Coke
      	Charge	
      Reduction of coke in cupola charges offers  some  beneficial
results.  The evaluation of cupola emissions,  described  in
Section VI, indicates that particulate emissions  tend  to decrease
as the amount of coke in the cupola charge decreases.  In addi-
tion, the replacement of the coke with lover cost fuels  results
in lower melting costs under certain conditions.
      Foundry operators contacted in the course of the study
expressed considerable dissatisfaction with the increasing cost
of coke coupled with a reported  decrease in quality.   In several
cases a distinct credibility gap exists with regard to proximate
analyses submitted by vendors.   An experienced cupola  operator
can quickly judge the coke quality by the furnace operation and,
in many cases, his judgment varies substantially  from  the
                 A T KFM»S'FY ft r•0^1P^VV 1^*-
                                                        IX  -  9

analysis submitted with each shipment.
      Heating of the cupola blast air has been recognized for
many years as one method of increasing the melting rate with
the same coke charged or of maintaining the melting rate with a
smaller coke charge.  Use of hot blast for only the latter
reason, however, is rarely practiced.  The economic benefit
of increasing the melting rate with hot blast is  too much
greater than the more moderate savings obtained by using less
coke at the same melting rate.  Neither have installations of
air heating units been made for the specific purpose of reducing
emissions level.  Only two hot blast cupolas listed in Exhibit
VI-11 are reported as having emissions below the  median of
36.5 pounds per ton of melt.  All unlined cupolas in the exhibit
use warm or hot blast to overcome the greater heat loss from  the
unlined shell and to increase the melting rate.
      Hot blast is universally achieved by means  of a fuel  fired
heat exchanger.  Natural gas is readily available in many parts
of the country for about $0.06/therm (100,000 BTU) for the
medium-sized user.  The coke replaced by the gas  costs approxi-
mately $45.00/ton delivered, representing a cost  of $0.155 per
100,000 BTU.  The operating cost savings amounts  to approximately
one dollar per million BTU of heat in the blast air.
      Oxygen enrichment of the blast air also results in a
decrease in coke requirements by eliminating the  80% nitrogen
in air which would otherwise require heating to the iron melting
                                                                                              A  T KFARS'FY & COMPANY  I - r

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                                                       IX - 10

temperature in the cupola.   Like  blase heating, however, oxygen
enrichment is invariably used  to  increase melting rate by in-
creasing the amount of oxygen  available  to  the coke.  An
accompanying benefit of the  80% reduction in volume of the
oxygen compared to the air  it  replaces is that specific blast rate
as related to melting rate  is  reduced.   The earlier emissions
analyses showed the correlation between  specific blast rate and
emissions rate.
      Enrichment of blast air  with 4% oxygen has been reported
to re."."1'- in savings up to  $1.50  per ton of mct^l melted by
permitting the use of less  costly metallies in the charge and
by increasing the melting rate up to 25%.   Test data quantifying
the reduction of particulate emissions resulting from oxygen
enrichment are not available.   The facts suggest, however, that
the installation of such a  system only for  the purpose of re-
ducing emissions would be uneconomical,  if  the cupola were
operated at the normal melting rate and  full advantage were taken
of decreased coke charge.
      Natural gas injection, like oxygen enrichment, provides
a means by which cupola coke requirements can be reduced, melt-
ing rate increased, melting costs lowered,  and a modest decrease
in particulate emissions realized.   The  major research effort
in this field has been briefly described in Section VI.  Results
of tests 12 and 11 in the research program  showed melting rate
increases of 37%, melting cost savings of 51.22 and $2.01 per
ton, and emissions rates down  about 15%  when 30% and 60% of the
                 A T hFARVFY
                                                        IX -  11

coke was replaced by natural gas.  The reported  cost  savings
include only the following unit operating costs:
           Coke              $40.00/ton
           Natural Gas         0.06/therm (100,000  BTU)
           Carbon              0.04/pound
           Silicon             0.159/pound
Amortization of the estimated $20,000-$35,000  equipment  invest-
ment is not included.  The discussion in Section VI emphasizes
the fact that emissions rates would probably be  lowered  more if
blast air had been reduced approximately in proportion to the
decrease in coke charge, but no test data are  available  for  this
condition.
      (c)  Prepartion of
      	Charge Materials
      The evaluation of cupola emissions  in  Section IV points
out that many of the emissions can derive from the presence of
undesirable materials in the charge.  These  materials  include
coke and limestone dust, sand, nonferrous metals,  and  a variety
of combustibles such as oil, grease, and  synthetics.   These
materials can be more or less completely  removed from  the charge
by more effective preparation of the coke, limestone,  and
metallic scrap, with a resultant decrease in cupola emissions.
      Screening of limestone and coke before loading into the
charging bucket is an elementary and inexpensive step  to prevent
breeze and dust from being charged into the  cupola.  A simple
grizzly bar screen for the mechanized foundry,  or  the  use of a
fork rather than a shovel in the manual foundry, will  suffice.
This precaution is commonly taken, but an occasional foundry,

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                                                      IX - 12
                                                                                                                                   IX - 13
Large or small,  is found  where  Che  absence of screening is
obvious from Che puff of  black  dust  from  the top of the cupola
as each charge is dumped.   The  investment is extremely nominal
and there is almost no operating cost.

      Removal of embedded molding and core sand from foundry
returns can be effected with a  shotblast  machine at an estimated
cost of $2.00 to $2.50 per ton.   This is  infrequently done,
however, due to its cost,  or the lack of  available equipment.  A
five-minute blast cycle is sufficient to  clean the returns.

      Other scrap preparation is more often performed by scrap
dealers than foundry personnel  due  to the equipment cost and
labor requirements.  More and more  of today's scrap is auto-
motive, consisting of whole or  broken engines or fragmented
bodies.  Charging of whole engines  into cupolas, as a significant
number of foundries do, results in  emissions problems from the
engine oil, grease, nonferrous,  and alloying materials from the
engine components.  Whole engines are available from scrap dealers
at a reported cost of $24-530 per ton.  Engines that have been
fragmented and stripped of the  large majority of nonferrous
components reportedly sell for  about $50  per ton.  Some scrap
dealers are equipped co break,  wash, and  strip engines on con-
tinuous lines consisting  of a breaker, detergent washing tank
and a supporting conveyor system including a picking or sorting
conveyor where nonferrous materials are removed.  This operation.
which removes all oil and grease from the scrap, adds $3.50-$4.00
per ton to the cost of the material.
      Cupola scrap as purchased from dealers contains  a minimum
of nonferrous materials, in large part because these materials
command a higher price, and it is to the dealers'  interest  to
separate them out for sale for the larger amount.  Nevertheless,
a certain amount of copper alloys and even more of the lower
value nonferrous metals find their way to the foundry  scrapyard.
The large mechanized foundry is not generally able to  sort  out
undesirable scrap due to the volume and method of  handling
employed.  On the other hand, the operator of a smaller foundry,
particularly one with manual or semi-mechanized charge makeup,
can instruct scrapyard personnel to set aside questionable  scrap
for little additional labor cost.
      Another problem, gaining importance with the increased
use of automotive scrap, is the inclusion of synthetic fibrous
material in shredded steel scrap derived  from auto bodies.  This
material, if not consumed in the furnace or by the afterburners,
tends to clog the collection equipment.  Except for the possi-
bility of this type of contaminant and its relatively  low
density, shredded automotive scrap offers an advantage for
cupola use in that the analysis is nearly constant, with little
nonferrous metallic inclusions.  Specifications for this
material should limit nonmetallic inclusions, by requiring
incineration or other suitable process.
                 A T
                                                                                            A  T KF1RVEY

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                                                       IX  -  14
                                                                                                                                IX  -  15
      (d)  Cupola Design
      	Changes	
      While minor design changes of conventional  cupolas  have
been shown to have little effect on cupola  emissions  rates,  one
newly developed cupola design is so revolutionary as  to warrant
special mention.
      The cupola is top charged through two charging  bells
roughly similar to a blast furnace.  Blast  air, preheated to
approximately 1100° F, enters the cupola through  tuyeres  located
somewhat below the bottom bell, raising the temperature of  the
coke to the ignition point.  The metal charge is  melted in  this
oxidizing zone and the molten metal along with the products
of combustion flow downward through the coke bed  in a reducing
atmosphere.  A portion of the particulate matter  in the gas is
absorbed by the coke and the molten metal and slag.  At the
bottom of the cupola, the molten metal, slag and  gas  flow into
an enclosed forehearth where outside air is mixed with the  gas
and secondary combustion is achieved.  At this point, particulate
and gaseous combustibles are burned.  At the same time, the
velocity of the gas stream is sharply decreased as it flows into
the forehearth, and additional particulate  matter settles out  on
the slag layer where it is absorbed.  The hot gases pass  through
a recuperative blast air heater and are exhausted to the  atmos-
phere.
      The design is currently being tested  on a full scale in-
stallation.  Preliminary test results show  emissions levels
rell below 0.05 grains per standard cubic  foot,  although  some
•perating problems are still being worked  on.  No  installation
>r operating cost data have yet been developed.
      (e)  Change Melting
          Method	
     The increase in the number of electric and  reverberatory
citing  furnaces in recent  years, at a time when  the  number of
ron  foundries have decreased  dramatically,  is  evidence that
ne acceptable solution to  the problem of  the high cost of
missions control is to replace the cupola by a furnace that
reduces less emissions.  Installation and melting costs as
hown in Section VIII are not  always lower,  but the total of
he advantages sometimes tips  the scale  in favor of cupola re-
lacement.   Exhibits  III-5  and III-6 show  the population changes
n types of  melting systems in recent years  and projections for
he next ten years.
     Growth patterns in the population  of electric arc and in-
action  furnaces have been  well documented.   In addition,
eported sales of reverberatory furnaces for iron melting are
eported to  be increasing as the result  of the  recent clean
ir laws.  Stack sampling test results for a reverberatory
jrnace  without any emissions  control equipment melting one ton
ar hour of  gray iron show  emissions of  0.82 pounds.   This
 nissions rate is well  below current minimums and explains the
 nterest of  the smaller foundries in the use of reverberatory
 jrnaces despite problems of superheating  the molten iron.  This
 ype  of  furnace in capacities  of  500, 1,000, 2,000 and 4,000 pounds
                  A  T  KFARVFY 8e rOMPXNY I •. f

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                                                      IX - 16
per hour are sold completely wired, piped and lined ready for use.
Installed costs including shipping charges, hood, stack, skip
loader, and reasonable connection costs are estimated to be as
follows:
          500 pounds/hour    -   $15,000
        1,000 pounds/hour    -   18,000
        2,000 pounds/hour    -   22,500
        4,000 pounds/hour    -   28,000
Capacities given are for melting and  superheating gray iron to
2750° F.  Capacities for melting malleable iron to 2650° F are
double those shown.  Manufacturers of reverberatory furnaces
estimate that sales of these  units will total 50-75 in 1970,
and that at least this many will also be sold in 1971.
      The reverberatory furnaces described above are all batch-
type melters.  A continuous type of fuel fired furnace has been
designed and installed on an  experimental basis in an operating
foundry.  Test data were not  available at the date of issue of
this report, but the designers  were hopeful of achieving the
dual benefits of lower cost melting than is possible in the
cupola and reduced emissions  generation.

Potential  Modifications
   to Other Melting Furnaces
     It  has  been demonstrated that melting emissions  from
induction  and  reverberatory furnaces  are generally  below
minimums established  by the various control bodies.  No modifica-
tions  to these types  of furnaces,  for the  purpose of reducing
emissions, have been  reported.   Electric melting is a batch
                                                         IX - 17

process requiring a  forehearth or  holding furnace to provide
the continuous supply of molten metal  possible from a cupola.
One major manufacturer has  reported  the  development of a con-
tinuous melting coreless induction furnace permitting a better
basis for comparison with cupola melting.   The furnace is "U"-
shaped with a horizontal coil located  in the center.   Preheated
charge materials are placed  in the charging leg and the molten
metal is discharged  from the top of  the  other leg.   No decrease
in melting emissions results from  the  new  design.
     Emissions -f-om  electric arc furnaces  tabulated in the
general foundry data range from 6  to 28  pounds  per  ton of metal
melted.  The variation in rate is  related  to operating practice
rather than to details of furnace  design.   For  this reason,  no
investigations into  possible design modifications  to  reduce
emissions are being  carried out as far as  is known.   Clean,
uncontamlnated scrap will, however, tend to decrease  emissions
as it does in the cupola.  The use of  an afterburner  to burn
combustible materials is particularly  beneficial,  since fabric
filters are almost universally used with arc furnaces.

Modifications to
  Magnesium Treatment
  for Producing Ductile
  Iron	
     Inoculation of  molten iron with some  form of magnesium
for producing ductile iron is inherently a violent  process
that is enhanced by  the need to provide  a  strong stirring action
for insuring complete mixing of the  inoculant with  the iron.
While the process is basically the same  today as when it was

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                                                      IX -  18
first introduced to the industry,  much progress has been made
in the development of different carriers for the magnesium and
methods of introduction of the inoculant into the metal bath
to slow the reaction, promote greater retention, and decrease
the resulting emissions.  Despite these advances the problem
is severe, particularly when the process is performed in the
open foundry area.  Attempts have been made to contain the
emissions in order to decrease environmental hazards as well as
to lower the cost of capture of the emissions.   These have
included the use of pressure ladles,  pressure chambers, ladle
covers with or without connections to an exhaust and collecting
system, and enclosed inoculation stations.   The pressure
systems are relatively expensive and time-consuming.  Compared
to less costly systems, they can usually be justified only when
the pressure is used to improve the effectiveness of the
nodularization.  Ladle covers at specific inoculation stations
have a nominal cost compared to pressure systems.  Inoculation
station enclosures can be installed for $2,500 or less, com-
plete with ductwork to an existing collector and prevent the
magnesium oxide and other fume from blanketing the whole
melting, pouring and mold making area.

Modifications to
  Sand Handling
  Systems	
     Foundry molding sand when moist does not produce emissions
while being conveyed from the mixer to the molding machines.
After pouring, however, the heat absorbed from the molten metal
evaporates a large part of the moisture, and sand fines become
                 A T KEM*SEY & COMP*XV I - «-
                                                                                                                                     IX - 19
airborne at the conveyor transfer points.  Conventional control
for this condition is to enclose these points with hoods and
connect all transfers to a dust collector.  A new concept of
dust control, recently patented, blankets the return sand with
moist prepared sand, effectively limiting the dusting normally
encountered.  The dust eliminating feature of the system is
actually an added benefit, since the concept was developed to
solve the problem of hot molding sand.

     In operation, excess molding sand is mixed and circulated
through the system with the overflow from molding requirements
discharged onto the return sand conveyor immediately following
the shakeout.  The ratio of sand prepared to metal poured is
in the range of 20 or 30 to 1.  Several benefits result  from
this excess of sand.  The heat of the shakeout sand is absorbed
by the prepared sand that blankets it, resulting in a very
nominal total temperature rise in the total mass.  Convection
cooling on the conveyor system dissipates most of the heat.
Because the proportion of shakeout sand to the total mass is
small, only small amounts of additives, such as bonding
materials and water, are required, and mulling time can  be
sharply decreased.  Additives are metered to the shakeout sand
immediately after the shakeout, and before the overflow  prepared
sand is discharged on the conveyor.  With moist sand forming the
top layer on the belt, no dusting occurs, and no dust collection
is required except at the shakeout.  The decrease in dust
collection requirements not only results in lower investment
needs, but also lowers operating and maintenance costs,  and

                 A T KFMJVFY Sc rOMP\VV I N «-

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                                                       IX  - 20

air makeup and heating costs.   Sand storage facilities  can be
reduced by as much as 80% since the majority of the sand is
constantly recirculating and being cooled.   Installations  have
been cited where savings of 50% in investment for the sand
storage bin, sand coolers and  aerators,  and dust collectors
have been realized for this process compared to conventional
sand systems.  Some additional capacity for millers and
conveying equipment may, however,  be required which will tend
to offset some of the savings.  A  highly variable cost  not
included in the above must also be considered.   Due to  the patents
outstanding for this process,  royalty payments  are required for
its installation and use.  Molding sand dust control systems for
conventional installations located in existing  foundries are often
extremely costly due to the necessity of fitting ductwork  into
crowded areas and around obstructions.   A cost  estimate for an
"average" installation of this kind is not  possible due to the
possible variations for each specific case.

POTENTIAL MODIFICATIONS
  TO EMISSIONS CONTROL
  EQUIPMENT	
     Improvements in emissions control equipment in the fore-
seeable future, with few exceptions,  promise to be minor in
nature.  These will be results of  efforts by the manufacturers
of this equipment to improve quality of manufacturing,  use of
better materials and redesign  to raise efficiencies and lower
costs of their products.  Three modifications have been
                A..T KEARNEY & COMPANY. Ivc
                                                       IX -  21

 reported  that  could  be  of  significant importance:   the develop-
 ment  of a high temperature metallic fabric for fabric filters,
 the use of a granular filter bed,  and a system of  cooling
 cupola emissions  in  a rain of sand particles  followed by a
 fabric filter.  No economic  analysis  is possible for these  de-
 velopments  since  cost data are not yet available.
      Patent applications have been reportedly filed for a
 metallic  fabric suitable for use as a dry filter system with a
 maximum gas temperature approaching 2000° F.   Few  additional
 details are available at this time.   The reported  expanded
 temperature range would permit installation adjacent to the fur-
 nace with little or no gas cooling by water sprays  or a convec-
 tion cooler.  The system drastically  reduces  the danger of  des-
 truction  by the heat or glowing particles  carried over into the
 filter.   In addition, the metallic  fabric  would  be  relatively
 immune from action of hydrofluoric  acid  resulting from fluorspar
 additions to the charge.  The  system  is  presently in the experi-
mental and pilot model stage  and has  not been  tested in a full
scale installation.
     A foreign manufacturer  of control equipment has developed a
control device using a granular material as a  filter bed for
cleaning   furnace gas.  The filter  bed material is reported  to
be a nearly spherical natural material with a  close diameter
tolerance that will  clean furnace gas  to 0.05  gr/scf.   Some
systems are reportedly working satisfactorily  in Europe.  Sales
representation in the United States is now supposedly  being
                                                                                                   A T KEARVEV & COMPANY INC

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                                                      IX  - 22
negotiated.  Full disclosure of details is expected within  a
feu months.

     Another emissions control device utilizing granular material
like sand for cooling cupola gas has recently been  announced  in
this country.  The use of sand size material as a heat  transfer
medium is effective because of the extremely large  surface  area
per unit weight.  This patented system uses a rainfall  of sand
in an enclosed tower through which the cupola emissions rise.
The cooled gas is cleaned in a conventional fabric  filter,  and
the heated sand is discharged into a second tower in which
fresh air rising in counterflow cools the sand to its original
temperature.  The cooling air also passes through a fabric
filter before being exhausted to the atmosphere.  The cooled
sand is conveyed to the upper level for reuse.  All equipment
utilized in the system is standard and has been proven  in
operation for many years.  While sand is abrasive and equipment
used for its transport requires regular maintenance, the prob-
lems are familiar to foundry personnel and require  no special
maintenance skills.
IMPACT OF POTENTIAL
  MODIFICATIONS TO
  FOUNDRY EQUIPMENT
  AND PRACTICES
     Exhibit IX-1 tabulates ten potential modifications to
cupola melting practices or equipment resulting in  either de-
creased cost of emissions collection or lower emissions rate.
Operating cost savings are significant for those items  that reduce
the volumes of stack gas required to be cleaned.  The first

                A T hEARVEY & COMPANY I •>. c
                                                      IX - 23

modification, small charging door and conveyor or chute charging,
is reported by cupola manufacturers as gaining wide acceptance,
and the majority of recent orders specify this feature.  It is
often, however, not an economical modification to an existing
installation.   The second item in the exhibit also is effective
but usually it is too costly to adapt an existing cupola to be-
low charge door gas take-off.  The "at charge door" take-off,
listed third, has not yet been proven from a technical stand-
point.  Since it can easily be installed on an existing cupola,
its success means that any foundry using a cupola for melting
can take advantage of one of three economical methods to sub-
stantially decrease the cost of collecting cupola emissions.
     The second and third categories of modifications listed in
Exhibit 1X-1 include methods to reduce cupola emissions up
to 25%.  The modifications to reduce coke requirements offer
operating cost savings up to $2.00 per ton of melt but result
in only moderate decreases in emissions.  Preparation of
charge materials to reduce or eliminate certain emissions com-
ponents results in additional operating costs up to $4.00 per
ton of melt.  None of these modifications, however successful
in reducing specific emissions, will result in the ability  to
use lower cost collection equipment, since they do not affect
the release of all fine metallic oxide particles.  Thus,
despite the additional cost of up to $6 or $7 per ton, the
same high energy systems will be required.
     It can therefore be said that it is less costly to provide
                                                                                                  A T KEARNEY & COMPANY INC

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                                                      IX  -  24

equipment to collect whatever emissions  are produced  in a rupol,-:
than to control the input of materials causing the emissions,
particularly when steps are taken to keep  gas volumes  to  a
practicable minimum.

     The other practical approach to the problem of the cost
and difficulty of collecting cupola emissions is to replace the
cupola with a different kind of melting  furnace.  Foundries
of medium size and larger, depending upon  local cost  and
availability of raw materials and fuel,  often find electric
induction or arc furnaces economically advantageous.   The small
foundry, and even some medium-sized foundries, for whom electric
melting investment requirements are too  great, may well find
reverberatory furnaces a low cost answer to the problem.  Cer-
tainly the entrepreneur with limited capital, wanting  to  enter
the industry, will find the reverberatory  furnace with its  low
first cost, and low emissions rate,  the  most practical approach
to the choice of iron melting equipment.
     The excess prepared molding sand system is expected  to have
relatively widespread effects on sand preparation in  iron found-
ries since it seems to solve the ubiquitous problem of hot  moid
ing sand.  Other potential modifications in non-melting applica-
tions are not expected to result in rapid  changes in  normal oper?t.-
ing methods or emissions collection capability.  Similarly  no r.aji.L
technological breakthroughs in emissions control systems, other
than those already discussed, are known  at this time.
                A T KFARKEY
                    X -  PROJECTION OF TRENDS
GROWTH  OF  THE
   IRON  FOUNDRY
   INDUSTRY
     The previous  discussion in Section III,  as well as
Exhibits III-l  through  III-6,  presented the historical
development of  the iron foundry industry,  particularly during
the postwar period.   The situation can be  described as one
in which the  small,  individually owned entrepreneurships
which once characterized the industry, are rapidly ceasing
to exist,  and are  being replaced by larger, corporately owned
foundries, with an ever-increasing percentage of the latter
being captive foundries.  The  growth of iron  castings output,
combined with the  reduction  in number of foundries by 50%
in a period of  less  than 25  years,  has resulted in more than
doubling the average  output  per foundry.

     It is particularly  significant  that the  reduction in
number of  iron  foundries  has been  almost entirely among the
small-sized companies.   While  the  medium-  and large-sized
foundries  have  remained  relatively  constant in number,  the
small foundries have  declined  to under half of their number
during the postwar period.  The  reasons  for this  are not
difficult  to trace.  The  increasing  costs  of  labor and  the
greater difficulty in recruiting and  holding  skilled foundry
                                                                                               A T KEARNEY & COMPANY  INC

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                                                     X - 2


labor have resulted in a. continuing increase  in  the degree of
mechanization in foundries.   It was once possible  to operate a
foundry on a very small investment in equipment, and to use
the same crew to perform all of the functions of melting,
molding, pouring, cleaning,  etc.  The modern  foundry requires
a high investment cost, with labor being fixed in  single  area
jobs, necessitating relatively continuous operation of the
shop.
     To all of these problems, the additional consideration of
environmental control is now being added.  This generally
requires  the installation of relati-ely high cost air, water,
noise,  and  other control systems, which further add to the
capital and operating costs without, by themselves, contri-
buting  to production or earnings.  This has caused many
marginal  operators to go out of  business, and can be expected
 to continue to  have this effect  in the  next  decade.  An
 analysis  of the iron  foundry population in the  state of
 California  during the  postwar  period has  shown  that the periods
 when strict enforcement of  air pollution  codes  were introduced
 were also the periods  of most  rapid decline  in  the number of
 iron foundries.
      The growth of production in the iron foundry industry
 has been projected by estimating the growth  rates for each of
 the principal segments identified previously, based on the
                 A T KEARVEY & COMPANY INC
                                                      X  -  3

growth of the user industry identified with that segment.  The
three were then combined to provide the input for  the total
estimated growth.  Total iron castings production,  excluding
ingot molds made from direct blast furnace iron, has been
projected to be approximately 17 million tons per  year by
1980, or an average of 27. increase per year.

     Iron castings production growth, as measured  by tons  per
year of output, has been somewhat behind the trends of some
of the other Industries, and has not kept up with  the trends
shown in the early 1950's.  This has probably been caused,
in part, by competition from other products and materials, such
as steel weldments, nonferrous castings and nonmetallics.  The
relatively moderate Increase in tonnage of output  has also
been caused by the improvement in technology which has enabled
thinner wall iron castings to be produced, resulting in  an
increase in the number of castings per ton of weight.  On  a
basis of quantity of castings, therefore, the growth of  output
of the iron foundry industry has more than kept up with  the
national gross product growth.
     The number of iron foundries which will be in operation by
1980 has been projected to be approximately 1,100.  Since  the  num-
ber of medium- and large-sized foundries has been  projected to
increase slightly, the entire drop from the 1969 total of  1,630
foundries to 1,100 foundries is expected to take place among the
                                                                                                  A T KEARWEY & COMP\VY I ..-r-

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                                                      X - 4


small-sized companies.   The combination of increasing output and
reduced number of producers is expected to continue to increase
the average output per  foundry to  an  estimated 16,500 tons per
year by 1980.   This is  almost four times  the average production
immediately after the war.

EQUIPMENT TRENDS
     The most significant changes  in  the  types and uses of
equipment which are expected to take  place in the iron
foundry are in the melting department.  The cupola, which
once was almost the only source of molten iron, has been
rapidly declining in number of installations, with the number
in 1969 being only about 45% of those in  existence immediately
after the war.  This decline has been projected to continue
at an undiminished rate, with the number  of cupolas in 1980
estimated to be about 1,300.  Although part of this decline
has been traced directly to the reduction in the number of
small-sized foundries,  it has also been related to several
other factors.  The principal one has been the replacement of
the cupola by other methods of melting, electric arc,
electric induction, and fuel fired reverberatory furnaces.
An additional factor has been the replacement, in many foundries,
of two or more cupolas by a single, larger-sized unit.
     In  1969, an estimated 85% of all iron melted in  iron
foundries was performed in cupolas.  As the  replacement of
                A.T KEARNEY &  COM PAN Y. INC.
                                                      X  -  5


cupolas by other forms of melting continues to accelerate,
the amount of iron melted in cupolas will decrease, with
the amount by 1980 projected to be as low as 50%  of the
total.  The electric methods of melting, both direct  arc
and induction, will account for almost 50%, with  the  small
remainder being melted in fuel fired, reverberatory furnaces.

     The electric arc furnace population has been projected
to be about 350 units by 1980.  Electric induction furnaces
have been projected to total about 1,350 units both coreless
and channel types, by 1980.  Reverberatory  furnaces have been
estimated to  increase to about 250 units by 1980.  All  of these
types of furnaces can be used for holding,  duplexing  and
superheating, as well as for melting of iron.  Therefore,  the
total of 1,950 furnace units other than cupolas  is not  to be
considered entirely as replacements  for cupola melting.   In
fact, probably as much as one-third  of  them will not  be used
for melting,  but will perform the other functions of  holding,
duplexing and superheating.
     Although the tonnage of malleable  iron which is  produced
has remained  relatively  constant, the number of  reverberatory
air furnaces  used for duplexing has  been  declining steadily,
as these types of fuel  fired  furnaces have  been  replaced by
electric furnaces,  principally arc  furnaces.   On the  other
hand,  the tonnage of ductile  iron has been  increasing every
                                                                                                A T KEARNEY 8. COMPANY

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                                                     X  - 6


year, and is expected Co be about double  the  1969  tonnage by
1980.  This will result in a corresponding increase  in the
amount of magnesium treatment of iron which will be  performed.
     The trend toward mechanization of molding, pouring  and
shakeout lines has been continuing at an  increasing  rate.
Most of the large- and medium-sized foundries  employ some
degree of mechanized molding.  With the development  of depend-
able and economical automated molding systems  for  small-sized
molds, many of the small foundries have installed  mechanized
lines.  Similarly, there are an increasing number  of foundries
in which continuous and automated sand handling and  preparation
systems have been installed.  There is every  reason  to believe
that within the next 10 years, the majority of iron  foundries
will use some form of mechanized molding,  pouring, shakeout
and sand preparation.
     Coremaking has also been undergoing  a technological
change, with the trend being away from oil-bonded, baked sand
cores, toward chemically bonded, thermally cured and air
cured cores.  Core processing is becoming mechanized and
automated.  Fuel fired core ovens are being replaced with
dielectric ovens, or with processes in which cores are cured
directly in the core boxes.
     The entire area of handling and preparation of  materials
used in the foundry is continually being  reviewed  with respect
                A T hEARMEY & COM PAW Ivc
                                                      X - 7


to the effect on emissions production and economy of collection.
Iron foundries are being more selective in purchasing of scrap,
with more attention being given to elimination of combustible
materials from the scrap before purchase.  Larger foundries
are installing scrap preparation facilities involving pre-
burning or cleaning to remove materials which will produce
emissions during melting.  Screening of coke and stone, and
use of higher quality briquettes are recognized as a means of
eliminating fines which will tend to blow out of furnaces
during melting.
     It is believed that the next generation will see an
increasing trend toward centralized scrap preparation yards
which will service many iron foundries in a given area.  This
will help to provide cleaner scrap at lower costs.

EFFECTS ON
  EMISSIONS
     Many of the trends toward electric or fuel fired melting
furnaces, mechanized molding, and continuous sand preparation
systems will have important effects in reducing the  quantity
of emissions produced, or in making the emissions easier or
less costly to collect.  The decisions made in selecting new
equipment are, therefore, being made to an increasing degree
with reference to the effect on reduction of emissions, or
on economy of emissions collection.
                                                                                               A T KEARNEY 81 COMPANY INC

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                                                     X  - 8

     The use of a greater amount of pre-cleaned or burned
scrap will reduce the quantity of emissions  from combustibles
now charged into furnaces along with the  scrap.  Screening
to remove fines will also help to accomplish this same goal.

     The trend away from cupola melting and  toward electric
or fuel fired melting furnaces will have  a significant effect
in reducing emissions.  The electric induction furnaces  and
the fuel fired reverberatory furnaces  produce a very small
quantity of emissions.  The electric arc  furnace emissions
are substantial in quantity, but are much tasier and more
economical to collect than are cupola  emissions.

     The mechanization of molding,  pouring,  shakeout and
sand preparation facilities has not reduced  the quantities
of emissions which are produced,  but has  resulted in confining
their production to fixed locations.   Thus,  it is relatively
simple in many cases to construct enclosures which can be used
as a means of collection of emissions  with a minimum of
infiltrated air.  This not only reduces the  size and cost of
the collection system, but makes  it more  effective, reducing
the amount of unconfined emissions  which  are released in the
foundry building.
               A T KEARNEY &  COMPANY INC
           XI - DEFINITION OF THE IRON FOUNDRY
           	AIR POLLUTION PROBLEM
GENERAL
     The widespread distribution of iron foundries and  the
prominence of the cupola stack in most communities in which
an iron foundry is located have combined to label Che iron
foundry as a major source of air pollution.  This opinion is
often strongly held by the downwind neighbors of a foundry
using an uncontrolled cupola for iron melting, and air  pollu-
tion control bodies receiving complaints of foundry  emissions.

     It is estimated that 243,000 tons per year of particulate
matter are generated from iron foundry melting operations, of
which about 182,000 tons are emitted to the atmosphere,  the re-
mainder being collected.  In addition, 1,504,000 tons per year
of particulate matter are estimated from non-melting operations
of which about 77,000 tons are estimated to be emitted  to the
atmosphere.  Total particulate emissions released to the atmos-
phere are therefore estimated at 259,000 tons per year.  Based
upon a 1968 inventory by NAPCA, of emissions from all sources, it
is estimated that the iron foundry contributes about 3.57. of all
particulate matter emitted by industrial sources, and about 0.9%
of all particulate matter emitted by all sources.

NATURE OF
  FOUNDRY EMISSIONS
     Particulate and gaseous emissions result from most iron
foundry operations, with the largest concentrations  being
                                                                                           A T KEARVEY & COMPANY Isc

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                                                       XI  -  2

emitted from cupola and direct electric  arc  furnace  melting.
Cupola emissions, as described earlier,  include  particulate
matter such as coke particles and ash, metallic  fume,  smoke  oil
vapor, and dust from sand and limestone.   Gaseous  emissions  from
the cupola include carbon monoxide from  incompletely burned  coke,
carbon dioxide, water vapor, nitrogen, and small amounts of  sul-
fur dioxide and fluorine compounds.   The last two  emissions
quickly hydrolize to form corrosive  acids.

     Electric arc furnace melting results in similar types of
missions except for those deriving from  the  combustion of coke,
and include metallic fume, oil vapor dust, and smoke and gase-
ous compounds from the combustible materials in the  furnace
charge.  Emissions from reverberatory and electric induction
furnaces are negligible, and control equipment is  rarely
employed on this equipment.
     Drying and preheating cause emissions similar to the
cupola except that the fuel most commonly used is  natural
gas instead of coke.
     Many operations, such as sand handling, raw material
storage and handling, charge makeup, molding and sand condition-
ing produce only mechanical dust emissions.   This  particulate
matter is neither corrosive nor toxic, as some components of
cupola emissions, nor an asphyxiant like carbon dioxide.  A
degree of hazard does exist however.from breathing the dust-
laden air over extended periods of time.  Similar mechanical
dusts result from several cleaning operations including

                  A T KEARN-EY & COMPANY Isc
                                                       XI  -  3
abrasive cleaning and grinding.  These metallic dusts  present
quite the same kind of health hazards if completely uncontrolled.

     The increased use in recent years of chemically bonded
core and molding sands has given rise to an additional type  of
emission.  Both the setting reactions and the combustion of  the
bonding material when the mold is poured result in smoke and
gaseous emissions that can be unpleasant and mildly toxic.
     A small percent of iron castings are painted before ship-
ment.  The process produces gaseous emissions consisting of
thinners and, depending on the equipment used, paint spray.
     Many foundries continue to use oil bonded cores requiring
oven baking for setting.  Gaseous emissions are produced
consisting of the more volatile fractions of the core  oil  and
some particulate matter such as smoke.
     The adverse nature of these various particulate and
gaseous emissions produced by foundry processes has long been
recognized.  Furthermore, to the distinct credit of the indus-
try, much has been accomplished through the years to control
emissions and to improve both the foundry and atmospheric
environment.  It is also important to note that efforts in
this direction were begun many years before air pollution
concerns achieved national prominence.
     It has been stated earlier that control devices for cupolas
were in use as early as 1938, and efforts to control non-
melting processes date back at least to the 1920's.  While
                  A T KEARS'EY & COMPANY INC

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                                                       XI - 4

 early equipment was crude and only  partly effective, industry
 pressure has resulted in steady improvement in efficiency and
 more widespread use of control equipment.

 INVENTORY OF
   FOUNDRY EMISSIONS
      The analysis of cupola and electric furnace emissions and
• the factors affecting the rates of  emissions showed that an
 average of 20.8 pounds of particulate emissions are produced
 per ton of metal melted in an iron  foundry cupola, and that
 an average of 13.8 pounds of parciculate emissions per ton of
netal melted result from direct electric arc furnace iron pro-
 duction.

      Exhibit XI-1 shows the total estimated particulate
 emissions generated by melting operations in foundries using
 cupolas and direct electric arc furnaces in 1969.  The
 exhibit shows total quantities for  each of nine geographical
 regions and the nationwide totals based on the molten iron
 production for the year and the above emission rates.   Based
 on a survey of iron foundries,  considering the number and
 capacity of furnaces equipped with  control systems, the
 effectiveness of the control systems, and the number of un-
 controlled furnaces, it is estimated that 75% of the particu-
 late emissions generated are presently being released  to the
 atmosphere.
                A T KEARNEY 8. COMPANY. Ivr
                                                      XI - 5

     Exhibit XI-1 also shows estimated quantities  of carbon
monoxide generated and emitted.  The  first estimate  is  based
on an average cupola operating with a 7/1 coke  ratio, using
coke with a carbon content of 91%, and with  11.6%  carbon
monoxide in the top gas.  Under these conditions,  276 pounds
of carbon monoxide is generated per ton of metal melted.
     The amount of carbon monoxide emitted to the  atmosphere
is dependent on a number of factors including the  temperature
of the top gas, the availability of infiltrated air  to  provide
oxygen for combustion, the completeness of combustion,  and
the percent of the total time that burning of the  carbon
monoxide occurs.  With sufficient oxygen from the  infiltrated
air and with constant combustion, the carbon monoxide content
should be completely burned.  Several factors tend to work
against this ideal condition, including the  flame  being
extinguished by each charge addition, lack of immediate re-
ignition either without an afterburner, or with an improperly
directed flame from an afterburner, varying  carbon monoxide
content precluding constant combustion, and  variable  air  supply.
A conservative estimate of 50% combustion efficiency  has  been
applied to the quantities of total carbon monoxide generated
to obtain the estimated weight of this gas emitted into the
atmosphere.
                                                                                              A T KEARVEY & COMPAVY 1 *c

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                                                     XI - 6

     The results of the calculations can be summarized as
follows for 1969 nationwide production levels:
          Total castings produced
          Total molten iron produced
          Total particulate emissions
           generated
          Total carbon monoxide
           generated
          Total particulate emissions
           emitted
          Total carbon monoxide
           emitted
16,614,000 Tons
24,367,000 Tons
   243,000 Tons
 2,924,000 Tons
   182,000 Tons
 1,462,000 Tons
     Particulates small enough to remain  suspended  in  air  over
an extended period are defined as aerosols.   The maximum diameter
of such particles h«« h^en variously  identified as  from 20 to  100
microns.  Using 50 microns as a limiting  diameter,  the aerosols
resulting from iron melting operations  amount to approximately
56% by weight of the total emissions  generated.  On this basis,
the suspendible particulate matter generated  by melting opera-
tions in 1969 amounted to 136,000 tons, of which approximately
102,000 tons was emitted to the atmosphere.   Particulates  over
50 microns diameter, totaling 80,000  tons for 1969, being  too
large to remain suspended, settled out  in a short  time depending
on meteorological conditions.
     The above data are derived only  from cupola and electric
arc furnace operation.  Emissions from  other  melting equip-
ment including induction furnaces and reverberatory furnaces
are negligible, not only because of conditions inherent to
these types of furnaces but also because  generally cleaner
scrap metal is used for furnace charges and a relatively
                 A T KEARNEY & COMPANY Ivc
                                                     XI - 7

small percentage of the total iron is melted in these furnaces.
Preheating of less clean scrap for charging into induction
furnaces will add significantly to the emissions inventory
only when the process is substantially more widely used than
it is now.  At its present level of application, preheater
emissions are also negligible.
     Emissions previously described from non-melting foundry
processes, with a single important exception, are often
controlled as a standard practice, generally affect only the
foundry environment, and are released to the atmosphere only
in minor quantities compared to cupola and electric arc
furnace emissions.  The concentration of these  emissions at
their source can be substantial as in the case  of  the  shake-
out, abrasive cleaning, and  griding, but the particles emitted
are  often large with a relatively high settling rate.   The
portion of the  particulate matter escaping  the  normal  collec-
tion ductwork tends to settle out within the foundry building.
     An analysis of non-melting operations  indicates that 114.91
pounds  of  emissions are generated for each  ton  of  metal melted,
but  that  only 5.83 pounds of this total are  released to the  at-
mosphere.   Normal  collection practices and  settling out within
the  foundry building account for  the difference between these
two  quantities.   Exhibit  XI-2 shows  the  total  estimated quantities
generated and emitted  to  the atmosphere  for the same nine geo-
graphical regions  tabulated  in Exhibit XI-1.   The  total estimated
weight  of non-melting  suspendible emissions from non-melting
operations in 1969 is  shown  in the  exhibit to be 76,600 tons.
                 A T  KEAR^CY & COMPANY. Ivc

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                                                     XI - 8

     The non-melting emissions  posing the greatest current
problem are those resulting from coremaking.  A minor problem
existed in the past when practically all cores were made  from
oil sand.  This type of core, however, is thermally cured in
a core oven, and the emissions  are relatively easy co capture
from the core oven stack for afterburning.  The use of  organic
chemical bonding agents, that are becoming more and more widely
used, intensifies the problem since these produce emissions
extremely difficult to capture  due to their method of appli-
cation.
     Molds or cores made from air set sand are often  set  out
on foundry floor or on racks while the sand sets.  The  local
environment in this situation is extremely poor.  Not only  is
it Difficult to capture the emissions over a large floor  area,
but the dilution of the gaseous emissions by the air  makes
the resulting mixture difficult and expensive to burn in  any
type of afterburner.

     The situation in many foundries for thermally cured
chemical binders when making shell or hot box cores causes
similar problems for the local  environment as well as after-
burning.  The resulting odors can be detected beyond  the
foundry property in many cases.

INDUSTRY
  PROBLEMS
     The air pollution laws established in recent years have
created many serious problems for the iron foundry industry
                A T KEARNEY & COMPANY. IMC
                                                      XI  - 9

beyond the determination of the proper emission control  equip-
ment to insure compliance with local codes.

     Code limitations on permissible emissions are anything
but static.  More than a few foundries have invested  substantial
amounts of capital in equipment to meet the first generation
codes, only to discover, a short time later, that restrictions
have been made more severe, requiring costly reworking of the
control equipment.  Current codes do not limit gaseous emissions
but all foundry owners are fearful that st'fingent" limitations
on carbon monoxide, sulfur dioxide and other gases are forth-
coming in the near future.  These conditions mean that the
equipment purchased now must not only insure compliance  with
present laws but also with future laws not yet drafted,  or
at the very least, must be flexible enough to permit  upgrading
in the future.

     The emission control system has been characterized  as a
profit-sharing silent partner that adds nothing to the value
of the foundry product but continually demands its share of
the profit.  This is an unwelcome situation at best for  the
large financially secure production foundry.  It can  be
extremely serious for the typically small, privately  owned
foundry with low profitability and with cash-flow problems.
For these reasons many foundries have been slow to react to
the need for emission controls.  In some states, a minor form
of relief is granted by waiving sales taxes on purchases of
equipment for air and water pollution control.  However,  other
assistance and incentive programs in terms of tax relief,
                A T KEARNEY & COMPANY INC

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                                                     XI - 10
                                                                                                                                   XI  -  11
faster write-offs, low Interest loans, assistance grants,
and similar approaches are necessary to promote rapid and
complete compliance without forcing the smaller firms out  of
business.  A national program applying uniform standards in
all areas that will aid all foundries In installing emission
control systems is required.  The development of a suitable
program requires additional study.

     State air pollution control laws vary widely in the methods
of determining permissible emissions from foundries.   One  of
the methods becoming more widely used is the process  weighc
basis in which permissible emissions are related to Che total
weight of all materials except air Introduced into the furnace
for a given time span.   Some codes differentiate between
existing furnaces and new furnaces,  or between jobbing foundries
and production foundries, and specify different permissible
emission rates for each.   Few of the codes,  however,  differen-
tiate between foundries that nay have the same process weight
per hour but operate widely different total  hours a week.   Thus
the small foundry melting only 10 hours a week requires the same
size and type of control system as another foundry with the same
size cupola, but is melting 80 hours a week.   The financial im-
pact of such a relationship can be seen in the cost per ton curves
and summary of operating costs given in the  exhibits  for Section
VIII.  The economic burden of a fabric filter for cupolas,  with
identical process weights of IS ton per hour,  for example,  but
operating at 1,000 and 4,000 hours per year  can be seen on  Exhibit
VIII-32 to be $4 per ton and $1.33 per ton respectively.
     It is evident that application of the same process weight
standard is not an equitable method and thnt consideration should
be given to the use of a longer time span than one hour.  Addi-
tional study would be required to develop a more reasonable and
equitable basis for applying process weight standards.

     Despite the rapid technological advances in emissions con-
trol techniques and equipment in the past few years,  a gap still
exists between foundry needs and equipment to meet those needs
efficiently and at a cost the foundry industry can afford to pay.

     With improvements in emission control capability desired
for each operation in all foundry departments, a basis for
establishing a degree of need and a priority ranking  for
research and development projects is obvious.  Page one of
Exhibit XI-3 presents a matrix listing the major emissions-
producing operations versus the important characteristics of
the emissions and the control equipment installation  required
for suitable control.  Page two of the exhibit shows  the rating
code appropriate for each characteristic, and the priority
assigned to each of three ranges of the total rating  for each
operation.  The operations indicating the greatest need, and
therefore the highest priority, are cupola melting and core-
making.  Research and development projects for improving
emission control capabilities in these areas are included in
recommendations developed in the following section.
                 A T HEABVEY 8t COMPANY IK c
                                                                                             A T KEA8SEY & COMPAVY INC

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                                                        XI - 12

                        REFERENCES

     1.  Nationwide Inventory of Air  Pollutant Emissions. 1968.
U.S. Department of Health,  Education,  and Welfare, Public Health
Service, Environmental Health Service,  Publication No. AP-73.
                 A T KEARNEY & COMPANY. INC
                   XII  -  OPPORTUNITIES FOR RESEARCH
                   	AND DEVELOPMENT	
NEEDS  FOR RESEARCH
  AND  DEVELOPMENT
     Although  iron  founding  has  been carried on for thousands
of years, the  application  of emission control techniques have
only been made in iron foundries for some 30 years.  Neverthe-
less,  in those few  years,  the techniques and equipment have
been improved  to the point where it  can now be reasonably
stated that means exist for  emission control for practically
all iron foundry operations.   However,  in many cases,  these
emission control methods or  equipment are not ecoi'or.uc-1 tr
install and operate, making  their use economically o.-C'.. jiL- ^.
particularly in small foundries.  The needs for research
development for emission control in  the iron found'-.'  •••uustr>
are therefore  largely economically oriented,  ained •   pt.-vi.di.ng
equipment and methods which can  be used by all SL  -.>  .-:" found-
ries without forcing them  out  of business.
Fundamental Knowledge
     Much of the presently used  control equipsPC  was  adapted
from other industrial uses, or was developed with  little or no
knowledge of the fundamental's  of emission evoli c.ion and the
nature of the emissions.    I-t  is believed that more basic under-
standing of these phenomena will provide necessary input for
development of more efficient and economical  means for control-
ling emissions.
                                                                                                A T KEARNEY & COMPANY. Ixc

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                                                      XII - 2


     The results of the regression analysis which was  conducted
as a part of this investigation clearly demonstrated the  lack
of quantitative data which related emissions to cupola design
and operating features.  Additionally,  the data which were col-
lected from stack tests on cupolas also demonstrated the  lack
of correlation which results when the testing is not done under
controlled conditions, in which all facts relating emissions
produced with operating factors and charge material variations
are not clearly recorded.   The research programs which are dis-
cussed are therefore proposed to be performed by qualified
laboratories under controlled conditions.  Among the questions
which must be answered are the following:
          1.  What are the basic relationships between melting
furnace design and operating features, and the production and
evolution of emissions?
          2.  What are the mechanisms by which very fine metal-
lic oxides are formed, and what variables affect their forma-
tion?
          3.  What causes iron oxide formation, and what varia-
bles affect rate and quantity of production'

Economic Factors
     The economic  factors involving emission control have been
shown  to be the most  important area for  further research and
development, particularly if methods are  to be developed which
can be applied  to  small foundries  and  at  the same time permit
                  A  T KEARNEY & COMPANY
                                                                                                                                 XII - 3
them to survive.   Research and development efforts are needed
to answer the following questions.
          1.   What can be done to reduce costs of collection
of fine particles?
          2.   What means can be developed to reduce costs of
installation and operation of dust  collection systems?
          3.   What means can be developed to economically
utilize waste heat in cupola stack gases7
          4.   Can uses be found for collected waste materials
which will aid in improvement of economy of collection?

Materials
          1.    Can fabric materials be developed for fabric
filter collectors which will resist high temperatures and
corrosive gases, and at the same time not be excessively
costly?
          2.  Can core binder materials be developed which
will not evolve acrid and noxious fumes during curing?

Processes
     What alternates can be developed for cupola melting
which will combine continuous operation with economy of
melting and  low emissions production?

ONGOING RESEARCH AND
   DEVELOPMENT PROJECTS
     Various research and development projects, covering a
number of aspects of iron foundry facilities and operation,
have been publicized or are known to be in progress.   Since
                 A, T KEARNEY & COMPANY INC

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                                                    XII - A

many companies do not publicize their research and development
activities, there are undoubtedly other projects which are now
in progress but which have not been made known to the industry.
Among the known projects, some of which were discussed in ear-
lier sections of this study, are the following.
Melting of Iron
          1.  A reverse draft, or what has been referred to as
an "upside-down cupola," has been developed by Mechanite Metals
Co. and is now in experimental operation at Combustion Engi-
neering Company's Mbnogahela foundry.  The intent of this cu-
pola is to reduce emissions evolution by forcing the blast air
downward through the cupola burden.
          2.  A continuous, gas fired shaft furnace for melting
of iron has been developed by Battelle Memorial  Institute and
is in experimental operation at the Cooper-Bessemer Company
foundry.  The purpose of the furnace Is to provide economical,
low emission melting of Iron.
          3.  A continuous, induction heated tneitiag furnace
for iron has been developed by Ajax Magnethermic Corp.  and
General Motors Corp., for the purpose of providing low emis-
sion, economical melting of iron.
          4.  A gas injection program on a cupola is being
conducted jointly by Battelle Memorial Institute and Campbell,
Wyant and Cannon at their foundry  in Muskegon.   The purpose is
to provide greater economy in melting,  reduced coke consumption,
                 A T KEARNEY & COMPANY. INC
                                                        XII  -  5

 and possibly reduced emissions.  Similar programs arc  also
 being conducted in other iron foundries in the United  States
 and in Europe.

 Emissions Collection
           1.   A new high temperature fabric with a new fabric
 filter collector design is being developed by a commercial
 foundry.
           2.   A new type of sand bed dust collector is being
 developed by  the Lurgi  Company in Germany.
           3.   A new type of dust collector utilizing a rain
 of  sand to collect  dust and heat,  and also to transfer the
 heat  to combustion  blast air,  has  been developed by Butler
 and Kutny.
           4.   A collection  system  utilizing the heat of com-
 bustion of the cupola gases  to preheat blast  air has been
 developed  by Holley, Kenney  &  Schott  and is in operation  at
 Majestic  Iron  Works  foundry.
           5.   A new  low cost method of wet  collection of  fine
 particles  is reported to be  in development  by National  Dust
Collector  Co.
          6.  A program  of waste product utilization has  been
conducted by Zoller Castings Company,  in which collected  cupo-
 la dust has been used as a fertilizer.
                                                                                              A T KEARNEV Sc COMPANY. INC

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                                                     XII - 6
PROPOSED RESEARCH AND
  DEVELOPMENT PROJECTS
     Based on Che needs  for research and development as pre-
viously described, the ongoing projects,  and  the  gap which
exists between available technology and needs,  a  series of
potential research and development projects has been assembled
and is described in the  following paragraphs.   These projects
nave also been summarized in Exhibit XII-1.  The  projects have
been grouped into associated programs involving fundamental
research, materials and  equipment development,  economic im-
provements, and standards development.  A pri.un.cy rating has
been applied to each project.  However, because of the previ-
ously noted fact that control technology and  equipment actually
are available for almost every iron foundry source of  emissions,
although not always at economical conditions, none of  the pro-
grams has been rated as  highest or urgent priority.
     Estimated costs have also been applied to each project.
In general, they were based on the work being performed by  a
research institute, university, or industrial research depart-
ment.  The actual costs  of research projects  are difficult  to
determine with any accuracy.  The costs given are, therefore,
intended only as order-of-magnitude figures to enable  an  assess-
ment to be made of the relative value of benefit of each  pro-
ject to the projected cost.
                  A T KEARNEY 8. COMPANY  INC
                                                                                                                                   XII - 7
Fundamental Research
  Projects _
     Project Nos.  1, 2 and 3 are a series of related programs,
involving research into the relationships which exist between
the quantity and type of emissions which are produced in the
cupola process, and the variables of design, operation and raw
materials used.  These programs are proposed to be carried out
on an experimental cupola by a qualified research institute or
a university with an experimental foundry.  They can also be
carried out in a commercial foundry if a cupola can be set
aside '-~r the work.

     No. 1.  Stack Sampling
     The first project involves a controlled  stack  sampling
program on a cupola to determine the  effect of  cupola design,
operating and raw material variables  on  the type  and quantity
of emissions which ore produced.  The goal of the program will
be to provide quantitative information,  which is  not now avail-
able to enable designers  of  cupolas and  emission  controls as
well as foundry  operators, to optimize design and operating
variables,  to result  in production of a  minimum amount of
emissions and to make them easier  to  collect.  The  stack samp-
ling must be accomplished under controlled conditions in which
the various design, operating and  raw materials factors can be
individually varied,  and  the effects  on  emissions noted.  A
program of  from  six months  to one  year in duration  is believed
to be required  to accomplish the desired results.  The cost of
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                                                     XII - 8
                                                                                                                                 XII - 9
such a program,  including a team of  three or four investigators,
cupola equipment,  test apparatus,  and  raw materials, is esti-
mated to be in the range of $150,000 to $200,000.  A top level
priority has been assigned to this program with relationship to
the other recommended iron foundry programs, since it is funda-
mental in nature and needed to carry out other recommended work.
There is no known research which is  being carried out in this
area.
     No. 2.  Iron Oxide Formation
     ..	Program	
     The second project is an extension of the stack sampling
program and probably should be carried out by the same re-
searchers.  The purpose of the work  will be  to conduct re-
search which will determine the mechanism of iron oxide for-
mation in the cupola, and the effect of operating and raw
materials variables on the quantity  of iron  oxide which was
formed.  Exhibit VI-14 suggested a possible  relationship be-
tween the type of scrap used and the potential amount of iron
oxide which  is present.  This should be confirmed in the pro-
posed research program.  The work has  been estimated to be
able to be carried out in a period of  four to six months by a
team of three researchers.  The estimated cost of such a pro-
gram, including cost of the team, the  experimental cupola,
test apparatus and raw materials, is in the  range of $50,000
to $75,000.  A medium level priority has been assigned to this
work, which  should be valuable in potentially reducing the
amount  of  iron  oxide present in cupola emissions.  There is no
known research  which is  being carried out in this area.

     No. 3.   Fine  Oxide-Opacity
     	Relationship Program
     The third  program is an extension of both the stack samp-
ling program  and the research into iron oxide formation, and
also can be carried  out  by the same researchers.   The purpose
of the work will be  to establish a relationship between the
presence of fine metallic oxides in cupola stack gases and
the opacity of  the gases.   The results of this program can be
used to develop new  opacity test standards which can more
effectively be used  as a means of measurement of emissions
levels than the presently used Ringelmann chart.   The time
required for  this work has  been estimated to be three to four
months, using a staff of two.   The estimated cost for the work,
including the research team,  raw materials and test apparatus
is in the range of $50,000  to $75,000.   There is  no known
research which is being  carried out in this area.

     The total fundamental  research programs which have been
proposed can be combined into a single  program to be conducted
by the same organization.   If  this  is  done,  the work could be
accomplished in about a  year with a team of about  six researchers,
at a cost in the range of $200,000  to  $300,000.
                 A T KEARNEY & COMPANY. INC
                                                                                            A T KEARNEY & COMPANY. Ivc

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                                                      XII - 10

 Economic Research
   Projects	
     We have previously noted that the principal area in which
 new development work remains to be done involves the economic
 effect of emission control on foundry costs.  Rigid enforce-
 ment of present control standards, combined with necessity of
 using existing designs of equipment, would have Che effect of
 forcing many of the smaller sized foundries out of business,
 and seriously affecting the earnings of medium and even large-
 sized foundries.  The group of programs included in the economic
 area includes a variety of approaches to the problem, involving
 improved raw materials, waste heat and waste product utilization,
 and reduced costs of collection.

     No. 5 Waste Heat Utilization
     The purpose of a development project for greater utiliza-
 tion of waste heat in cupola stack gases is to improve the
 economics of cupola melting and emission control.   Two potential
 sources of heat energy are proposed to be investigated.   The
 first covers the sensible heat in the hot cupola stack gases,
which is in the range of 180 to 320 BTU per pound of gas,  while
 the second covers the heat of combustion of the CO in the stack
 gas, which is in the range of 4,350 to 8,700 BTU per pound of
 gas.  The work is proposed to be accomplished by a research
 institute,  or by a builder of melting or emission control
 equipment.   A program of about six months'  duration involving
a staff of three researchers is proposed to investigate  past
 attempts at waste heat utilization,  evaluate them,  and develop
                 A T KEARSEV & COMPAVV  Ivc
                                                     XII - 11
a new method which will combine sensible heat and heat of
combustion recovery.  The estimated cost of such a program is
in the range of $100,000 to $150,000.  The benefit will be
achieved by reduced coke consumption during melting, which
will also reduce costs of melting and reduce emissions levels
from the cupola.  Although the waste heat recuperator, utilizing
the Griffin system, was commonly used in cupola installations
more than 20 years ago, the high costs of maintenance and low
reliability have made it obsolete.  Known development programs
include a proposed system for cleaning gases and recuperation
of heat by use of a sand stream through which the gases pass1
and a combination gas scrubber and combustion unit  for pre-
            o
heating air.
     No. 7.  Centralized Scrap
     	Preparation Development
     The high costs of scrap preparation, with particular ref-
erence to removal of combustibles and nonferrous metals, has
resulted in poorly prepared scrap being used in many  foundries.
The purpose of the proposed development project  is  to enable a
centralized scrap preparation facility to be installed  in a
community, serving numerous iron foundries and providing pro-
perly prepared scrap of minimum cost.  This will promote use
of this scrap and will result in reduced emissions  from melting
operations.  This program can be carried out by an  engineering
firm, or by a large scrap metal organization.  A three  co four
month study using a team of two engineers is proposed, at an
estimated cost of $30,000 to $50,000.  A medium  level priority

                 A T KEARNEY «c COMPAVY Ive

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                                                     XII  -  12

has been assigned to this project.   No known work  is now being
carried out in this area.  However,  a  study was made by the
U. S. Bureau of Mines on dismantling of junk automobiles to
                      3
produce quality scrap.
     No. 10.  Waste Product
     	Utilization
     At present, the collected emissions from  iron foundry
operations are not utilized for any  purpose of value other
than for landfill and,  in fact, are  costly to  remove from
foundry sites for disposition.  The  purpose of this proposed
project-is to develop potential uses for these waste products
which may help pay for the costs of  collection and may even
provide some revenue.  The development project would consist
of an investigation into past and present attemps  to utilize
waste products from iron foundries and similar Industries, an
investigation of the analysis of typical waste products, and
the development of potential uses for  these products.  This
work is proposed to be carried out by  a research institute,  a
university, or an engineering company.  A program  of three to
four months' duration utilizing a staff of one or  two investi-
gators is envisioned, at an estimated  cost of  $20,000 to $30,000.
Because of the marginal possibility  of a positive  result,  a
low level of priority has been assigned to this project.
Development work in this area has been carried out by the
Zoller Castings Company, which has used collected  emissions  as
fertilizer on farmland, and by Swindell Dressier Co., which  has
                                                  ^
conducted a study on the use of steel  plant wastes.
                 A T KEARNEY & COMPANY IHC
                                                      XII -  13

Materials Development
  Projects	
     In certain areas involving evolution  or  collection of
emissions in the iron foundry, equipment exists  for  the required
purpose, but optimum materials have not yet been developed  to
make use of known equipment or techniques.  The  projects in
this group are directed toward development of new or improved
naterials.
     No. 4.  High Temperature
     	Fabric	
     Fabric filter collectors are known to be the most  efficient
n-eans of emissions control.  However, their use  in melting
operations has been limited, and their cost of operation has
been increased by the lack of availability of fabric materials
which will resist high temperatures over 500° F  and  at  the  same
time resist the corrosive action of stack  gases  which result
fron use of fluorspar in the cupola charge.   A program  of de-
velopment of temperature and corrosion-resistant fabrics, re-
lated if necessary to changed design of the baghouse collector
system, is proposed.  Such a new material  will result in an
increased.utilization and reduced cost of  operating  fabric
filter collectors.  This work can be carrie'd  out by  a research
institute, or a manufacturer of fabric materials.  The  program
has been estimated to involve at least six months, using a
staff of three researchers, with appropriate  test equipment.
The cost has been estimated to be in the range of $75,000 to
$100.000.  Because of existence of several research  projects
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in this area, a medium level  priority has been assigned.  Known
development work is being carried out by a  research company and
a. manufacturer on a new fabric material combined with a new
collector design.  Additional work has been conducted by NAPCA
on endurance tests of high temperature  fabrics,5 and endurance
tests on fiber glass fabrics.6
     No. 8.  Low Emission Core
             Binder Materials
     The preparation of oil bonded sand cores,  which were
cured in an oven, results in oil fumes which are relatively
easy to capture, and which can be incinerated by use of a
catalytic combustion unit.  However, the increasing use of
chemically bonded core materials which are cured in the molds
or on racks without use of an oven, produces fumes which are
difficult to capture, are acrid and often toxic in nature,
and which are difficult to convert into harmless, odorless
gases.  The proposed research program involves the development
of new core binder materials which produce the desired physical
properties in cores and which do not give off noxious fumes
during curing.   The goal  of  the work will be to eliminate the
 fumes which are generally associated with coremaking operations
 and with subsequent pouring  of molds.  This work is proposed
 to be  performed by a research institute, or by a manufacturer
 of chemicals  used  in cores.  A  six-month program Involving
 three  researchers  at an  estimated  cost of §100,000  to $150,000
 has  been envisaged.  A medium priority  level has been assigned
                   A  T KEARNEY & COMPANY INC
                                                        XII -  15
  to this work.  Although no research programs in this area have
  been reported, it is believed that some of the manufacturers
  of core additive materials are engaged in such work.
  Development of
    New  Equipment
      The  principal  area  of new  equipment  development is in
 melting of  iron, with  specific  reference  to  replacement of
 the cupola  by other melting methods which will  still provide
 some of the desirable  features  of the cupola, without some
 of the undesirable  features.  The important other area  for
 new equipment development is in new dust  collection  systems
 of lower cost and higher efficiency.  Two such areas  have
 been selected for proposed research and development  projects.
      No.  6.   Continuous Melting
      	Furnace 	
      The  principal  advantages  of the cupola  for iron melting
 are  that  it  is a  continuous nielter and  an  economical melter,
 and  it  is  capable of using a wide variety  of  metallic charge
 materials.   The principal disadvantage, which has  been well
 documented in this study,  is that it produces  a  large quantity
 of emissions which are  difficult and costly to collect.   The
 alternate methods of melting which are now in  use—electric
 arc,  induction and reverberatory are all batch-type melters
 and,  with the exception of the electric arc,  are not capable
 of using a wide range of metal scrap  in the charge.  The
proposed development project  involves the  design and construc-
tion  of  a  continuous, fuel fired  or electrically heated,

               A  T KEARVEY & COSTP-xv>- i.

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                                                    XII - 16
melting furnace,  which will be economical  to operate, and
which will produce a low level of emissions.  It should also
be capable of being built and installed  for a relatively low
costs.  The benefits of such a furnace will be largely felt
by the smaller foundries which are now faced with the com-
bination of high cost melting and emission control installa-
tions.  The development program can be best carried out by
a research institute, a furnace builder, or a large foundry
with a development department.  A program  of up to one year,
utilizing a staff of four people, at an  estimated cost of
$200,000 to $300,000 is believed to be necessary.  In view of
known research now being carried out in  this field, a medium
level of priority has been assigned to the project.  Two pro-
jects of this type are known to exist.   The first involves a
joint development by Battelie Memorial Institute and Cooper
Bessemer Co., covering a gas fired, vertical shaft furnace.
The second involves General Motors Corp. and Ajax Magnethermic
Corp. and covers a continuous induction  heated melting furnance.

     No. 9.  Agglomeration of
             Fine Emissions
     The cost of emission control, particularly on melting
operations, increases rapidly as the particle size to be
captured decreases.  Submicron sized particles are very
costly to collect, requiring high pressure-drop wet scrubbers,
baghouses or electrostatic precipitators.  However, if it
were possible to agglomerate fine particles into coarse
particles, efficiency of collection could  be improved, and
                A T KEARNEY St COMPANY. Im.
                                                     XII - 17

collection costs could be  reduced.   The proposed projects is
directed  toward the development  of  a means of agglomeration
of Cine particles into coarse  particles,  using sonic or
electrical means for accomplishing  this.   This work can be
accomplished by a research institute,  or  by the development
laboratory of an emission  control equipment builder.  A
project involving five to  six  months of time, utilizing a
staff of  three, at an estimated  cost of $75,000 to $100,000
has been  contemplated.  A  low  level of priority has been
assigned  to this work.  No known research is being carried
out in this field.
                A T KEARNEY 8, COMPANY I»c

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                                                     XII - 18
                          REFERENCE

     1.  Butler, Kucny,  "A New Approach for Cupola Emission
Control," Modem Casting. June, 1970.
     2.  "Cupola Off-Gas Scrubbing with Recuperation",  "33"
Magazine. 1969.
     3.  Dean, "Dismantling a Typical Junk Automobile to
Produce Quality Scrap,"  Bureau of Mines,  No. 2350, December,
1969.
     4.  M. A. Osman, "Preparation of Useful Products from
Steel Plant Dusts,"  Swindell-Dressier Company,  1969.
     5.  J. M. Yacher, "High Temperature Fabric  Filter Study,"
NAPGA, 1969-70.
     6.  Spaite, Harrington, "Endurance of Fiberglass Filter
Fabrics,"  Mapea, 1967.
     7.  AraaLa, Walker, "Continuous Induction Iron Melting,"
A.F S. Transactions, 1970.
(IBLIOORAPHIC DAT* <• »'»<" «•• (*•
fHMT APTO-OGad 1
Systems Analysis of Emissions and Emissions Control
Iron Foundry Industry Volume I - Text
In the
?. Auhorh)
». f»«i«va| O>B»iuini «•«* ""I Ad 22. PtictL .
P^raCL»SSiriED ^I?lt70
                A  T KEARNEY S COMPANY I-s c

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This report was furnished to the
A1r Pollution Control Office by
the A. T. Kearney In fulfillment
of Contract No. CPA 22-69-106.

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