United States      Industrial Environmental Research  EPA-600/7-79-045
Environmental Protection  Laboratory         February 1979
Agency        Research Triangle Park NC 27711
Assessment of  the Use
of Fugitive Emission
Control  Devices

Interagency
Energy/Environment
R&D Program Report

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                 RESEARCH REPORTING SERIES


Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, havo been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of  traditional grouping  was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:

    1. Environmental Health  Effects Research

    2, Environmental Protection Technology

    3. Ecological Research

    4. Environmental Monitoring

    5. Socioeconomic Environmental Studies

    6. Scientific and Technical Assessment Reports (STAR)

    7, Interagency Energy-Environment Research and Development

    8. "Special" Reports

    9. Miscellaneous Reports

This report has been assigned to the INTERAGENCY ENERGY-ENVIRONMENT
RESEARCH AND DEVELOPMENT series. Reports m this series result from the
effort funded  under the 17-agency Federal Energy/Environment  Research  and
Development Program. These studies relate to EPA's mission to protect the public
health and welfare from adverse effects of pollutants associated with energy sys-
tems. The goal of the  Program is to assure the rapid development of domestic
energy supplies in an environmentally-compatible manner by providing the nec-
essary environmental data and control technology. Investigations  include analy-
ses of the transport of energy-related pollutants and their health and ecological
effects;  assessments of, and development of,  control technologies  for  energy
systems; and  integrated assessments of a wide-range of energy-related environ-
mental issues.
                        EPA REVIEW NOTICE
 This report has been reviewed by the participating Federal Agencies, and approved
 for publication. Approval does not signify that the contents necessarily reflect
 the views and policies of the Government, nor does mention of trade names or
 commercial products  constitute endorsement or recommendation for use.

 This document is available to the public through the National Technical Informa-
 tion Service, Springfield, Virginia 22161,

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                                               EPA-60G/7-79-C45

                                                     February 1979
                                 of the           of
Fugitive  Emission  Control
                                by

                        D.P. Daugherty and D.W. Coy

                        Research Triangle Institute
                            P.O. Box 12194
                  Research Triangle Park, North Carolina 27709
                         Contract No. 68-02-2612
                             Task No. 48
                        Program Element No. EHE624
                     EPA Project Officer: Dennis C. Drehmel

                   Industrial Environmental Research Laboratory
                     Office of Energy, Minerals, and Industry
                      Research Triangle Park, NC 27711
                             Prepared for

                  U.S. ENVIRONMENTAL PROTECTION AGENCY
                     Office of Research and Development
                          Washington, DC 20460

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                                 ACKNOWLEDGEMENT

     This report presents the results of a study conducted under EPA Contract
68-02-2612, Task 48.  The research was conducted in the Industrial  Process  Studies
Section of the Energy and Environmental Research Division of the Research Tri-
angle Institute (RTI).
     RTI acknowledges the time and courtesy extended by St.  Joe Lead Company
during a visit to their Herculaneum, Missouri smelter and, equally,  the  consid-
eration shown by Kennecott Copper Corporation during a vist to their Hayden,
Arizona smelter.  The Ransburg Corporation and Dr.  Stuart Hoenig of  the  University
of Arizona at Tuscon provided useful information on charged fog spray devices.

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                                TABLE OF CONTENTS

                                                                           Page
ACKNOWLEDGMENT                                                               iv
LIST OF TABLES                                                               v1
LIST OF FIGURES                               •                             v1ji
     1.0  INTRODUCTION AND SUMMARY                                            1
     2.0  CONCLUSIONS AND RECOMMENDATIONS                                     5
     3.0  FUGITIVE EMISSION SOURCES, RATES,  AND COMPOSITIONS       '           6
          Lead Smelting                                                       6
               Process Description of Lead Smelting                           6
               Fugitive Emission Rate Data-for Lead Smelting                 14
               Fugitive Emission Size and Composition Data
               for Lead Smelting                      '                       15
          Copper Smelting                                                    22
               Process Description of Copper Smelting                        22
               Fugitive Emission Rate Data for Copper Smelting               26
               Fugitive Emission Size and Composition Data for
               Copper Smelting                                               26
     4.0  CHARGED FOG SPRAYS FOR CONTROLLING FUGITIVE EMISSIONS              33
          Description of Charged Fog Spray Device                            33
          Collection Efficiency of Charged Fog Sprays                        37
               Impaction/Interception                                        37
               Diffusion                                                     38
               Phoresis                                                      38
               Electrostatic Attraction                                      41
          Basis of Collection Efficiency for Commerical  Devices              47
          Cost Data and Utility Consumption  for Charged  Fog Sprays           50
     5.0  WATER SPRAYS WITH ADDITIVE'S FOR CONTROLLING FUGITIVE EMISSIONS     57
     6.0  BUILDING EVACUATION FOR CONTROLLING FUGITIVE EMISSIONS             59
          Description of Building Evacuation                                 59
          Cost and Utility Consumption for Building Evacuation               61
     7.0  COMPARISON OF CHARGED FOG SPRAYS WITH BUILDING EVACUATION          63
     8.0  REFERENCES                                                         72

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                                   TABLES
                                                                          Page
        Summary of Charged  Fog Spray Comparison With Building               3
        Evacuation
 2       Summary Table  —  Basis for Total Particulate and Elemental
        Lead  Fugitive  Emission Rates:  Primary Lead Smelter                 7
 3       Summary Table  —  Basis for Total Particulate and Elemental
        Lead  Fugitive  Emission Rates:  Primary Copper Smelter               9
 4       Relative  Contributions From Various Emission Sources to
        Fence!ine Concentrations  of Ambient Lead at Primary Lead
        Smelters                                                           15
 5       Emission  Factors  for  Lead Smelting as Measured by MRI              16
 6       Lead  Concentrate  Compositions                                      17
 7       Composition  of Sintering  Emissions                                 18
 8       Lead  Content of Fugitive  Emissions From Lead Smelting
        Operational  Areas                                                 19
 9       Particle  Distribution for Fugitive Particulates From
        Lead  Smelting                                                      20
10       Particle  Distribution for Ducted Lead Sintering Machine
        Gases                                                              21
11       Distribution of Pb, Cd, Zn, and Cu in Respirable Range Near
        Primary Lead Smelter                                              21
12       Airborne  Elemental  Concentrations Near  Primary Lead Smelter        22
13       Composition  of Copper Concentrates Processed in the U.S.           27
14       Elemental Concentrations  in Air by Copper  Smelter Area,
        Industry-Wide  Averages                                            28
15       Composition  of Ducted Copper  Converter  Dusts From Bar,
        Yugoslavia                                                         29
16       Estimated Composition of  Fugitive Particulates by Copper
        Smelter Area                                                      31
17       Percent of  Metal  Aerosols in  Respirable  Range:  Converter,
        Furnace and  Crane Aisle  Employees in  U.S.  Copper Smelters         32
                                         VI

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                                 TABLES  (cont'd)
Number                                                                Page

 18       Particle Distribution for Ducted Copper Converter Gases      32

 19       Particle Distribution for Ducted Copper Reverberatory
          Furnace Gases                                                32
 20       Summary of Total Estimated Costs for Charged Fog Spray
          Device                                                       51
 22       Estimate of  Installation Material Costs for Charged Fog
          Spray Device                                                 53
 23       Estimate of  Installation Labor Costs for Charged Fog
          Spray Device                                                 54
 24       Estimate of Auxiliary Equipment Costs for Charged Fog
          Spray Device                                                 55
 25       Energy Consumption for Operating a Charged Fog Spray
          Device                                                       56
 26       Capital and Operating Costs for B'uilding Ventilation
          System at Typical Copper Smelter                             62

 27       Potential Applications for Charged Fog Sprays in Lead
          Smeltering                                                   64
 28       Potential Applications of Charged Fog Sprays in Copper
          Smeltering                                                   65
 29       Comparison of Charged Fog SPrays With Building Evacuation    68

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                                     FIGURES

Number                                                                Page
  1        Flowsheet of Typical  Lead Smelting Operations                 10
  2       Flowsheet of Typical  Copper Smelting Operations               24
  3       Means of Producing  a  Charged Water Spray                      34
  4       Particle Trajectories Around a Water Droplet.                 39
  5       Diffusiophoretic  and  Thermophoretic Forces                    40
  6       Limiting Charge for Water Droplets       "                  •   42
  7       Typical  Charge  Distribution for Micron Size  Particles         43
  8       Effects  of Particle Size, Droplet Size, Relative  Humidity,
          and Electrostatic Charge on Collision Efficiency              45
  9       Lifetime of Water Droplets  Traveling at Their  Terminal
          Velocity                                                     48
 10       Schematic of "Dead  Spots" in Building Evacuation  System      60
 11        Charged  Fog Spray Application Points in Lead Smelthing        66
 12       Charged  Fog Spray Application Points in Copper Smelting      67
 13       Push-pull  Local Hooding Versus Charged Fog Spray  Curtain     70

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                    ••   1.0   INTRODUCTION AND SUMMARY

      Emissions  from stacks and other so-called "point sources"  have,  in  the
 past,  been  the  main target of pollution control efforts.  Windblown  losses
from storage piles,  dust from material  handling, fumes  from  hot metal  transfer,
and many other sources  in  the metals industry are not considered point sources.
Instead, pollutants  from these diffuse, non-ducted sources are termed
"fugitive emissions."   This report compares three fugitive control  techniques--
building evacuation, charged  fog sprays, and water sprays with addi-tives--as
they might be applied  in lead and copper smelters.
      Fugitive emissions from lead and copper smelters have serious impacts
on more than just  the  total suspended part4culate levels; they may  also
contain toxic metals for which separate ambient standards exist  or  are being
contemplated.   The report  estimates  (from admittedly rough base-data)  the
reduction of total  suspended  particulate emissions and the reduction  of
elemental lead emissions from smelters when fugitive control  is  applied.
Primary lead and copper smelters are considered; secondary smelters are not.
      The control  techniques  of charged fog water sprays are  emphasized in this
report.  (These  sprays  enhance particulate collection by putting an electro-
static charge on fine  water droplets.)  Building enclosure and evacuation is
used as a basis  with which such water sprays are compared.  Secondary hooding
is not evaluated as  a  control method, as it is being studied  by  others.
      Several  limitations  on  the scope of this project need to be mentioned,
No sampling  was  done to measure fugitive emission rates  or compositions;  values
used in' the  report are cited  from prior publications.  Likewise, even though a
copper smelter and a lead smelter were visited to discuss'using  charged fog
sprays with  plant  engineers,  there were no field trials  as part  of  this project.
Instead, available cost and energy consumption data was  used  to  assess whether
charged fog  sprays are competitive with other devices.
      Charged fog  sprays are  only, beginning to be commercially applied;  a
small version with a maximum  spray rate of 0.25 gpm is now commercially available.

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No independent test data of charged fog spray efficiencies in industrial
applications have been presented to date.  In general:  (a)  while  for
uncharged sprays, there is a minimum in the collection efficiency  for about
two micron diameter particles, there is not any such minimum for charged  sprays
and some improvement  in collection of respirable dust is expected  from charging;
(b) the charged fog sprays are best suited to localized sources  of dust,
suspended in a low velocity or stationary gas stream; (c)  the combination
of high temperatures  and excessive gas turbulence rules out charged fog sprays
for areas such as copper converter leakage or furnace taphole emission control;
and (d) at reasonable water application rates, the charged fog sprays are
unlikely to have efficiencies approaching 90 percent—overall collection
efficiencies on the order of 50-60 percent are more likely.
      Capital costs,  utility requirements, and control efficiencies were
estimated for both building evacuation and charged fog spray control  techniques.
The results are summarized in Table 1.  Note that the reduction  of fugitive
emissions cited are on the basis of total fugitive emission  including open
source emissions such as windblown dust which are outside  the control of
either a building evacuation system or a charged fog spray.   The efficiencies
for sources within the control of building evacuation or charged sprays were
taken as 95 percent and 60 percent, respectively.
      While both capital investment and energy consumption are higher for building
evacuation, the reduction of total particulate and elemental lead  emissions are
also greater for building evacuation because of the higher collection efficiency
and the larger number of sources covered by a building evacuation  system.   About
10 to 20 k$ are required for each percentage reduction in  emissions by spray
versus 100 to 200 k$  required for each percent reduction for building evacuation.
Similarly the electrical requirement is much lower for the charged fog sprays--
15 to 30 kW for each  percentage reduction versus 150 to 200  kW for the
building evacuation system.
      However, in spite of the apparent attractiveness of charged  fog sprays,
the authors feel that there are several practical problems which prevent  them
from supplanting building evacuation or secondary hooding  as fugitive control
techniques.  The first and main objection is their limited applicability.
Water sprays are only suitable when the process can tolerate water, when  the
                                                                                    L

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   TABLE 1.   SUMMARY  OF  CHARGED  FOG SPRAY COMPARISON -WITH BUILDING EVACUATION .
Item                                         Lead Smelting     Copper  Smelting

Reduction in  fugitive total  particulate
  emissions
   by application of  charged sprays                30%              20%
   by application of  building evacuation           45%              40%
Reduction in  fugitive elemental  lead
  emissions
   by application of  charged sprays                40%              35%
   by application of  building evacuation           75%              65%
Estimated capital investment
   for application of charged sprays               311  k$           366 k$
   .for application of building evacuation         8,683  k$         6,'808 k$
Electrical  requirement
   for application of charged sprays               417  kW           450 kW
   for application of building evacuation -       9,000  kW         6,000 kW
emissions are from localized sources,  when  there  is  not  a  great deal  of air
turbulence and when the air is  not  at  high  temperatures.   These limitations
rule them out for such major sources of fugitive  emissions as converter leakage,
sintering discharge, and metal  tapping, pouring,  and casting.
     A second major limit on charged fog spray  control  is  the collection of the
agglomerated particles.   It is  usually assumed  that  once  suspended particles
collide with a water droplet,  they  are permanently  removed from the atmosphere.
This is a valid assumption for  such applications  as  conveyor transfer points
in moderately sill air where the agglomerated dust  settles out and is returned
to the process.  However, when  particles from,  say,  a railcar unloading station
are contacted with spray droplets,  they may settle  out  on  the ground, dry
out, and be reentrained.  Particle  control  has  only  been  temporary.  The
severity of this phenomenon is  a major uncertainty  for  future large scale
industrial applications of charged  fog sprays.
     It makes more sense to consider charged sprays  and building evacuation
as complementary control devices instead of mutually exclusive techniques.

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Per high temperature, large scale, turbulent emissions,  either  building  evacuation
or secondary hooding are required to collect the fugitive  emissions.   Charged
fog sprays are better suited for smaller, localized emission  sources.  Two
applications for which charged sprays may be particularly  advantageous over
other controls are:  (a) mobile sources such as  front-end  loaders  (where any
other type of control is impossible), and (b) areas such as sanders or grinding
wheels where personnel  exposure must be reduced  without  impeding access.
     Water sprays with surfactant additives  can  be  used  to reduce  dust entrain-
ment from hard-to-wet solids, but have an advantage over conventional water
sprays only for reducing dust generation from dusts which  have  not already been
suspended.  Surfactants do not substantially improve the collection of particles
which have already become airborne.   Thus, they  are'not  substitutes for  charged
fog spray applications.  The addition of surfactants or  other additives  should
be considered for such applications  as conveying and storage  bins  where  the
product is not water sensitive and can be kept moist to  reduce  dust entrainment
from the solid.  Additives other than surfactants may be used in some cases to
form a "crust" on  storage piles, etc., and  reduce  windblown  resuspension of
dust.
     More detailed discussions of the material above, together  with information
on the smelting processes and the composition and amount of fugitive emissions
are presented in the main body of this report.

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                    2.0  CONCLUSIONS AND  RECOMMENDATIONS

      For equivalent degrees  of control,  charged  fog sprays  require  roughly
one-tenth the capital  investment and utility  requirement  of  building
evacuation.   However,  the nature of charged fog sprays  limit them  to a
maximum of 50-60 percent collection efficiency versus 95  percent for
building evacuation.
      The charged fog sprays  are not expected to  perform  well  in high tempera-
ture, very turbulent,  open areas encountered  in many of the  major  sources  of
smelter fugitive particulates:   converter leakage,  sintering discharge,  and
hot metal tapping and handling.
      There is no data currently in the public domain regarding  the  efficiency
of charged fog sprays  in industrial environments.   The  device cannot be  con-
sidered, at this point, established technology.   The next logical  step  in
development of the product is independent testing done  on some industrial
application of the sprays.  This testing  would define and document the
performance of this device outside the laboratory.  Several  questions
regarding its performance in  evaporating  conditions, cross-drafts, and  rigorous
environments need to be answered.  Should the initial tests  prove  favorable, other
applications such as spray curtains or mobile charged spray  devices  could  be
evaluated.
     It is recommended that field evaluation  and  sampling  of the charged fog
spray device in  an industrial application  be  conducted  as  a  follow-up of this
study.   The  estimated  time required for such  a sampling program is one man  year.

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             3.0  FUGITIVE EMISSION  SOURCES,  RATES,  AND  COMPOSITIONS

     Primary lead and primary  copper smelting are discussed  separately in  this
section.  The sources, rates,  and  compositions of fugitive particulate emissions
are discussed for both.   Neither stack  emissions nor fugitive  gaseous  emissions
such as S02 are included.   The study was  limited to  smelter  operations between
ore receipt and the casting of crude metal  ingots.
     The smelting processes are described briefly, emphasizing factors which
alter the amount or composition of fugitive particulates.  Although no single
flowsheet can represent the variations  between smelters,  technology most common
to United States smelters  has  been depicted.  After  this, the  best available
data for fugitive emission rates,  by processing step, are discussed.   Sadly,
even the best estimates for rates  are just that and  not  very reliable—few
sources have been measured, and the  measurement techniques for fugitive emissions
                                                         2
only yield rates accurate  within a factor of  two to  five.    Emission  rates are
presented solely as a basis for comparing control devices; in  this use, inaccuracy
in their measurement does  not  obviate the comparison.
     Composition data for  the  fugitive  emissions conclude the  discussion of
each smelting process.  This data  was obtained from  several  sources;  references
are given. This composition data was combined with source emission rates to
yield Tables 2 and 3 which show the  base  rates of total  particulate emissions
and of elemental lead emissions.   This  pair of tables is  later used in Section
7 to compare the emissions reduction from installing charged fog  sprays with
that obtained via building evacuation.
LEAD SMELTING
Process Description of Lead Smelting
     Figure 1 depicts the  lead smelting process steps commonly used in the
United States to produce metallic  lead  from the concentrated ore.  The figure
is presented to acquaint the reader  with  the  operations  in primary lead smelting.
                                                    3-7
Several sources were used  to develop this flowsheet.      It  represents no
single smelter, but instead is a composite of the operations in several

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       TABLE 2.   NUMMARY TABLE-BASIS FOR TOTAL PARTICULATE AND ELEMENTAL LEAD FUGITIVE
                 EMISSION RATES:a'b
                 PRIMARY LEAD SMELTER, 100,000 METRIC TONS PER YEAR
Source of Fugitive Emission
1.











2.


3.











4.




5.




6,




7.


Railroad car and truck
unloading
Limestone

Silica sand

Lead ore concentrate

Iron ore

Coke

Btast furnace flue dust
a. Storage
b. Handling and transfer
Limestone
a. Storage
Loading onto pile

Vehicular traffic

Loading out

Wind erosion

b. Handling and transfer

Silica sand
a. Storage

b. Handling and transfer

Lead ore concentrate
a. Storage

b. Handling and transfer

Iron ore
a. Storage

h. Handling and transfer

Coke
a. Storage

Total Paniculate
Operating
Parameter
metric tons/yr


Limestone unloaded
39,700
Silica unloaded
1,800
Lead ore unloaded
158,900
Iron ore unloaded
22,600
Coke unloaded
47,200

-
-


Limestone loaded
39,700
Limestone stored
39,700
Limestone loaded out
39,700
Limestone stored
39,700
Limestone handled
39,700

Silica stored
1,800
Silica handled
1,800

Concentrate stored
168,900
Concentrate handled
158,900

Ore stored
22,500
Ore handled
22,500

Coke stored
47,200
Fugitive Emissions
Uncontrolled
Emissions
metric tons/yr


4

0.19

17

2.5

9.5


Negligible
Negligible
_

1

2.5

1

2

4


0.5

0.5


26

264


14.5

22.5


3.5

Elemental Li
Weight Fraction
Lead Contained
in Emission


0

0

0.60

0

. 0


-
-


0

0

0

0

0


0

0


0.60

0.60


0

0


0

;ad Fugitive Emissions
Uncontrolled
Lead Emissions
metric tons/yr


0

0

10.2

0

0


0
0


0

0

0

0

0


0

0


15.6

158


0

0


0

See footnotes at end of table.

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 TABLE 2. (cont'd)
Source of Fugitive Emission
7, Coke {continued)
h. Handling and transfer
S. Mixing and penalizing'
9. Sinter machine
10. Sinter return handling
11. Sinter machine discharge
and screens
12. Sinter crushing0
1 3. Sinter transfer to dump
area
14. Sinter product dump
area
15. Charge car or conveyor .
loading and transfer of
sinter
16. Blast furnace— monitor
(tatal)d
17. Lead pouring to ladle
and transfer
18. Slag pouring9
19. Slag granulator and
slag piling
20. Dross kettle
21. Rflverberatory furnace
leakage
Total Paniculate
Operating
Parameter
metric tons/yr

Coke handled
47,200
Lead produced
100,000
Sinter produced
349,979
Sinter produced
175,000
Sinter produced
175,000
-
Sinter transferred
175,000
Sinter dumped
175,000
Blast furnace charge
238,600
Lead produced
100,000
Lead produced
100,000
-
-
Lead produced
100,000
Lead produced
100,000
22. Lead casting Lead produced
100.000
SUBTOTAL NOT INCLUDING RESUSPENDEO DUST
23. Resuspended djst3
TOTAL FUGITIVE EMISSIONS

Fugitive Emissions
Uncontrolled
Emissions
metric tons/yr

4
114
58
788
131
c
17.5
1
61
a
47
e
f
24
150
44
1,823
740
2,563
Elemental Lead
Weight Fraction
Lead Contained
in Emission

0
0.40
0.40
0.40
0.40
-
0.40
0.40
0.40
0.35
0.50
-
-
0.25
0.25
0.50

Fugitive Emissions
Uncontrolled
Lead Emissions
metric tons/yr

0
45.6
23.2
315
52.4
c
7
0.4
' 24.4
2.8
23.5
e
f
6
37.5
22
744
74
813
Footnotes
3 Rates are only estimates to be used as a basis for comparing alternate control devices.
b Emission rates are from Reference 2, pp. 2-130 to 2-149 prorated by K to convert from 200 Mg/yr to 100 Mg/yr.
c Emissions for sinter crushing included in emissions from sinter machine discharge and  screens.
  Emissions for charging, blow condition, and tapping included in total.  Emission factor for upset not considered part of normal
  operating conditions and is not included in emission factor for the blast furnace roof monitor.
8 Emissions for slag pouring included' in lead pouring to ladle and transfer emission.
  Granulated slag is wet and, therefore, most likely not a source of fugitive emissions.
3 Resuspended dust contributes additional 10 percent to elemental lead  (Reference 13), Lead content of resuspended  dust assumed
  to be 10 weight percent to calculate total resuspended dust.

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           TABLE 3,   SUMMARY TABLE-BASIS FOR TOTAL PARTICIPATE AND ELEMENTAL LEAD FUGITIVE
                      EMISSION RATES:3'6
                      PRIMARY COPPER SMELTER, 100,000 METRIC TONS PER YEAR
Source of Fugitive Emission
1. Unloading and handling of
ore concent rate1-
2. Ore concentrate storage
Loading onto pile
Vehicular traffic
Loading out
Wind erosion
3. Limestone flux unloading,
handling, and storage
4. Roaster charging
5. Roaster leakage11
6. Calcine transfer
7. Charging reverberatory
furnace
8. Tapping of reverberator/
9, Reverberator/ furnace leakage9
10. Slag tapping8
11. Converter charging
12. Converter leakage
13. Slag tapping from converter
14. Blister capper tapping
1 5. Blister copper transfer
16. Charging blister copper to
fire refining furnace
17. Copper tapping and
casting
Total Participate
Operating
Parameter
metric tons/yr
Ore concentrate
337,000

Ore concentrate loaded
337,000
Ore concentrate stored
337,000
Ore concentrate loaded out
337,000
Ore concentrate stored
Limestone flux
153,000
-
-
-
Copper produced
100,000
-
-
-
Copper produced
100,000
-
-
-
-
Capper produced
100,000
Capper produced
100,000
13. Slag tapping and handling3 -
SUBTOTAL NOT INCLUDING RESUSPENDEO DUST
19. Resuspended dust
TOTAL FUGITIVE EMISSIONS

Fugitive Emissions
Uncontrolled
Emissions
metric tons/yr
1,690

.7.0
22.1
9.0
18.1
25,4
d
d
d
_ 425
e
e
e
602
f
f
f
f
95
126
9
3,020
2,013
5,033
Elemental Lead
Weight Fraction
Lead Contained
in Emission
0.0167

0.0167
0.0167
0.0167
0.0167
0
-
-
-
0.015
0.015
0.015
0.015
0.020
0.020
0.020
0.020
0.020
0.010
0.010
0.010

Fugitive Emissions
Uncontrolled
Lead Emissions
metric tons/yr
28.2

0.11
0.37
0.15
0.31
0
0 •
0
0
6.38
e
e
e
12.0
f
f
f
f
0.95
1.26
g
49.7
1.0
50,7
Footnotes
3 Rate: are only estimate! to be used as a basis for comparing alternate control devices.
b Emission rates are from Reference 2, pp. 2-115 to 2-129.
c Also include] slag handling.
  Emissions from roaster charging, leakage, and transfer ate not included because of clean natures of newer roasting processes
  (e.g., Fluosolids).
1 Emissions from reverberatory tapping and leakage are included in emission factor for reverberatory charging.
f
  Emissions from converter leakage and tapping, and blister copper transfer are included with converter charging emission factor.
^ Emissions from slag to tapping are included in casting building emissions.
  A resuspended dust contribution of 40 percent of total emissions was assumed. Lead content of resuspended dust was assumed
  to be 0.05 weight percent (Reference 27).

-------
                                 HETUMH HAG
                                       TRIPTEH CONVEVOK
              NT'W^xWWWWx^
QRANULAItNC WA|£K
                                       Figure 1.  Flowsheet of Typical Lead Smelting Operations.

-------
smelters.  The  purification  and  transport of lead smelting byproducts such as
silver and zinc are  not  shown  in  this figure.  Neither is the processing of
lead ore  into concentrate.   Ore  processing and concentration is typically
                                                      o
handled at the  mine,  and has been discussed elsewhere.
     Manufacturing lead  metal  from  a concentrate of sulfide ores (mainly galena,
PbS) involves three  steps.   First,  lead sulfide is converted into lead oxide
and lead  sulfate by  burning  80-90 percent of the sulfur in the ore by a process
called sintering.  The oxidized  lead (called sinter) is then reduced to metallic
lead by heating with  coke in a blast furnace.  Finally, the molten crude lead
is refined to remove  any remaining  metals--commonly copper, zinc, antimony,
silver, and tin.
     As mined,  lead  ore  is not concentrated enough to be processed 'in a smelter.
The ore is crushed to a  fine powder which is concentrated via flotation to
between 45 to 75 weight  percent  lead.  This concentrate is shipped to the
smelter via rail cars, trucks,  or  barges where it is unloaded and transferred to
storage bins.   The unloading,  material handling, and storage of concentrate is
a potential source of fugitive emissions with high lead content (typically 60
weight percent  lead.)
     The  concentrate  is  mixed  with  fluxes and return slag to make a feed for
the sintering process.   The  sintering machine is a travelling grate on which
the sulfur in the concentrate  is partially burned.  To control the sulfur
content of the  sinter machine  feed, some of the sinter product is blended with
the fresh feed  to the sintering machine to lower the sulfur content to 5-7
weight percent.   About 10 percent of the total  feed to the sintering machine is
laid down on the  grate and ignited, with the remainder of the feed being spread
on the burning  ignition  layer.
     On the sintering machine, the  heat generated by the burning sulfur fuses
the sinter into  a hard clinker.  The clinker (called sinter) is crushed to less
than five inches  and  screened.  The coarse sinter is the feed for the blast
furnace and the  finer material is returned for blending with fresh feed.
     Material handling,  sinter crushing, and particulate escaping the sintering
machine hoods all contribute to fugitive emissions in the sintering building.
                                        11

-------
Discussions with lead industry engineers  indicated sintering and  the  associated
crushing as probably the largest process  source  of fugitive particulate in  lead
         g
smelting.
     In the next processing step, sinter,  coke,  and  flux are charged  to a blast
furnace.  The coke is consumed in the  blast  furnace  and reduces  the  sinter  to
molten lead.  Fresh sinter and coke  are  periodically added to maintain  the
furnace charge height.  The molten mass  in the furnace bottom is  settled into a
layer of molten lead and a lighter slag  layer.   The  molten material  may be
tapped continuously or on an intermittent  basis.  Typically, the  molten slag is
granulated with a water jet and then dumped  in open  piles.
     Fugitive emissions from the blast furnace are normally low,  but  may become
significant during process upsets.  The  pressure  af  the top of  the blast furnace
normally is sufficiently low that gases  passing  up through the  furnace  are
sucked into the central collection hood  and  do not enter the work space dir-
ectly above the blast furnace.  If the blast furnace charge is  not porous
enough, high pressures can build up  across the furnace charge and in  extreme
circumstances blow particulate into  the  working  area.  Another  problem  occurs
when a "blowhole" develops and the hot gases preferentially bypass the  main
body of the furnace charge through a channel  which has formed.   Very little
visible fugitive particulates are seen from  the  slag granulation.
     Most zinc originally present in the ore concentrate ends up  in  the blast
furnace slag.  When the economics so dictate, and the smelter has the proper
equipment, the zinc can be recovered in  a  zinc fuming furnace.   Only three  of
the six U.S. lead smelters have zinc fuming  furnaces, and  these operate inter-
mittently, depending on the zinc market  conditions.   Fugitive emissions from zinc
fuming furnaces have been reviewed in  another report.    They are not considered
in this report because most lead smelters  do not have zinc fuming furnaces.
     More variation is found in the  refining areas of lead smelters  than in the
other two' processing steps; refining is  designed around the ore source  available
to the smelter.  The content of copper and other trace metals varies between
ores, but in general ores can be classified  as Missouri or non-Missouri lead
ores. Missouri lead ores contain traces  of silver and cadmium,  but little
copper or others impurities.  Accordingly, their refining  is  not as  involved
                                         12

-------
as that  for  the more  complex ores.  Missouri lead ore accounts for over 80
                                    1
                                    5
percent of the ore mined in the U.S.    Accordingly,  the  following  refining
sequence  is from a Missouri smelter.'
     Molten lead bullion  from  the slag settler is moved through a series of 250
ton capacity,  hemispherical refining kettles.  First the bullion is transferred
to a dressing  kettle where sulfur and other additives are added and the metal
is cooled.  At about 430° (800°F), copper and other impurities  solidify and are
skimmed off and transferred to a reverberatory dressing furnace.  In the dressing
furnace,  soda  ash is melted with the dross and causes it to separate into (a)
matte which is solidified and  may be shipped to a copper smelter for recovery
of the contained copper,  and (b) lead bullion which is recycled to the dressing
kettle.   Impure lead from the  dressing kettle is reheated in a  desi-lvering
kettle where zinc is added and a crust enriched in silver and gold is removed
as the metal cools.  To remove zinc remaining in the lead, a subsequent kettle
fitted with a  vacuum hood is used to vaporize zinc from the molten lead.  As a
final refining step, caustic soda and niter are added in a refining kettle.
The remaining  impurities  rise  to the surface and are skimmed off.  The refined
molten lead is then cast  into  pigs or ingots.
     Fugitive  emissions from the refining process consist mainly of fumes from
molten metal handling.
     There are several material handling operations in the smelter which have
not been  specifically mentioned above—an in-plant rail system is typically
used to transport quantities of slag to the dump, baghouse dust to storage
bins, and make other batch materials movements; the molten lead bullion is
moved via ladle cars and overhead crane ladles; and slag, although usually
granulated, may be moved  in wheeled slag pots.  The operation and movement of
front-end loaders, trucks, and other vehicles can create fugitive dust emissions.
     A final source of fugitive particulate, often neglected but quite im-
portant,  is windblown dust resuspended from the ground, storage piles, or open
areas around the smelter.  In  the integrated iron and steel industry, such open
source fugitive emissions have been estimated to be roughly the same magnitude
                                              12
as fugitive emissions from process operations.
                                        13

-------
Fugitive Emission Rate Data for Lead  Smelting   •
     Particulate emissions that are from  fugitive  (i.e., non-ducted)  sources
have not received the same level  of study that  point  sources  (i.e.,  stack
emissions) have.  Accordingly,  emission rate factors  for fugitive  sources  are
not well established; few reliable measurements  have  been made.  Available rate
data is of questionable accuracy, but since the  purpose of  this  report  is  to
compare alternate control methods, rate data is  presented and used as a base
case for comparing charged fog  sprays with building evacuation.  Only with a
clear understanding of its limitations should the  data be used for any  other
purpose.
     PEDCo Environmental, Inc.   has prepared a  list of fugitive  emission factors
for a hypothetical 200k metric  tons per year lead  smelter.  The  average capacity
in 1976 of the six United States  primary  lead smelters   was  only  about 100k
metric tons per year, and the PEDCo factors have been prorated by  one-half to
prepare the emissions rates shown on  Table 2.   The smelting flowsheet used by
PEDCo to estimate fugitive emission rates is not the  same as  that  presented in
Figure 1, but it is felt that the emission factors are not  accurate enough to
justify a complete recalculation  of emission rates.   Some modifications of the
PedCo emission rates were made—the contribution from the silver retort building
and the contribution of the zinc  fuming furnace  listed in the PEDCo tabulation
are not included in Table 2.  Also, a contribution from particulate resuspended
from open areas was added.
        13
     TRC   has pointed out that there may be a  large  contribution  from  resus-
pended particulate deposited on the plant grounds.  They estimated the  effect
of resuspended particulate by comparing ambient lead  measurements  from  periods
of normal smelter operation with  those from times  when the  smelter was  shut
down because of strike or holiday. Their data  are summarized in Table  4 and
are the basis of the resuspended  dust contribution added to the  fugitive
emissions inventory.  Table 4 data indicate that about an additional  10 percent
contribution to elemental lead  (not total particulate) is made by resuspended
particulate.  For the source inventory in Table 1, this resulted in an  extra  74
metric tons per year of elemental lead.   To get an estimate of the total
suspended particulate contributed by  resuspension, the 74 metric tons per year
                                       14

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  TABLE 4.  RELATIVE CONTRIBUTIONS FROM VARIOUS EMISSION SOURCES  TO FENCELINE
            CONCENTRATIONS OF AMBIENT LEAD AT PRIMARY LEAD SMELTERS*
Plant

Bunker Hill
ASARCO, El Paso

St. Joe
ASARCO, Glover
Automobile
3
ug/m
0.5
0.4

0.2
0.4
Resuspension
3

4.6
2.7
h
1.5/0.5°
1.5d
Stack plus
fugitive9
3
wg/m
10
27
h
8/16°
15
Total
3

15
30
h
10/17°
17
Resuspension
as a percent'
age of total
46
10
K
19/3°
10C
*Data is from Reference 13.
aThe numbers presented represent long term averages (i.e.,  if two. years  of
 data are available, the value would be a two-year average).   Individual
 monthly averages would range higher.
 Upwind data/Downwind data.
Insufficient data were available for an accurate resuspension contribution.
 The number presented is based on the assumption that the fall-off rate  is
 similar to that exhibited by the other plants.

of lead were converted to 740 metric tons per year of total  particulate  by
assuming a lead content of 10 weight percent.  It is recognized that this
resuspended contribution is only a gross approximation.   It is included  to
give a truer picture of the total fugitive emissions from a smelter.
                                                                   c
     Fugitive process emission measurements done by Constant et al.   are presented
in Table 5.  Their data considers fugitive emissions from an entire  operation,
such as from the individual processes of a sinter building,  as one source.
Fugitive Emission Size and Composition Data for Lead Smelting
     Several sources were used to obtain composition and size data for
fugitive emissions.  The compositions were used to calculate elemental lead
emission rates from emission factors for total suspended particulates.  This
section discusses the origins of the composition data used in Table  2.
     Galena (PbS) is the major lead-bearing mineral in-the ore concentrate
fed to lead smelters; pure galena contains 86.6 weight percent lead.   Smelter
concentrates vary from around 45 percent up to 75 percent lead and contain
                                       15

-------
         TABLE 5.  EMISSION FACTORS  FOR LEAD  SMELTING AS MEASURED  BY  MRI*
                                 Total  Emission  Rate of Fugitive Particulate
                                  Glover,  MO  Plant    East  Helena, MT Plant
    Operation                          Mg/y                    Mg/y

    Sinter Building                    19.4                    10.3
    Blast Furnace                      19.5             '        5.5
    Dross Kettles                       ---                    „-, cb
                                                              4/ .b
    Reverberatory Furnace               —
    Ore Storage Bins                    1.3                     —
    Plant Total                        40.2                    63.4b

    *Yearly emission rates were  calculated from  Ib/day data in Reference
     6 assuming 350 d/yr of smelter  operation.
    aAverage of dross kettles  and reverberatory  furnace.
     Total  does not include 2.2  Mg/yr from a  zinc fuming facility  or  5.3 Mg/yr
     from a zinc furnace which were  listed in Reference 6.

varying amounts of minor impurities  depending on the ore source.   Table 6
shows the range of lead concentrate  compositions cited in the  referenced
articles.  Sixty percent lead  was used  in  Table  1 for fugitive emissions from
concentrate handling.  No lead enrichment  in  these  fugitive emissions is
expected, since the ores have  not yet been exposed  to temperatures which might
produce fume that is enriched  in volatile  metals.
     The lead content of fugitive emissions around  the sintering machine was
taken as 40 weight percent based on  the data  in  Table 7.  Note that the final
two columns in Table 7 given compositions  of  fugitive emissions from  two
sintering buildings as measured  in Reference  6.  (There are three  values men-
tioned for lead content of sintering building emissions in  Reference  6:  58
percent in Table 11; 27.5 percent in Table 10; and  34.5 percent calculated
from Table 8.  The mid-value has been shown.)
     For lead contents in other  operation  areas, Table 8 of this  report pre-
sents sampling data from Reference 6.   As  is  seen,  there is little consistency
in the numbers.  In this report, the authors  have:   (a) used 35 weight per-
cent lead for fugitive emissions from the  blast  furnace area,  since about  10
                                       16

-------
TABLE 6.  LEAD CONCENTRATE COMPOSITIONS
Weight Percent Unless Otherwise Specified
Constituent
Pb
S
Zn
Fe
Cu
CaO
As
Sb
Bi
Cd
Ag
Au
Reference 8
45-60
10-30
0-15
1-8
0-3
tr-3.0
0.1-0.4
0.01-2.0
tr-0.1
tr
0-50 oz/t
0-"few" oz/t
Reference 14
55-70
13-18.5
0-6.5
0-5
0.5-4
tr
tr
No Data
No Data
tr
tr
tr
Reference 15
70
No Data
1.5
No Data
0.5
No Data
No Data
No Data
No Data
0.2
No Data
No Data
Reference 7
72
No Data
0.8-2.9
No Data
0.9
No Data
No Data
No Data
No Data
No Data
1 oz/t
No Data
Reference 17
76.1
15.6
1.0
3.9
0.04
0.25
0.28
0.12
0.04
No Data
35 oz/t
0.48 oz/t
                                                                                      4

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                                                   TABLE 7. COMPOSITION OF SINTERING EMISSIONS
WEIGHT PERCENT UNLESS OTHERWISE SPECIFIED
CONSTITUENT
Pb
S
Zn
Fe
Cu
CaO
As
Cd
Ag
FEED3
40-46
5-7
no data
no data
no data
no data
no data
no data
no data
FEEDb
32.0
10.6
5.6
9.4
2.0
4.5
no data
0.05
30-150*
FEED0
42.2
4.2
3.6
no data
no data
no data
0.38
0.0020
no data
PRODUCT6
42.0
1.86
3.93
no data
no data
no data
0.36
0.0020
no data
PRODUCT11
35.5
1.4
10.0
9.7
2.9
10.3
no data
0.04
30-150*
PRODUCT11
28-36
0.75-1.6
9.5-12.5
12-15.5
0.6-1.5
9.0-10.5
no data
no data
10-21*
ROOF
MONITORd
34.8
no data
no data
no data
no data
no data
0.033
no data
no data
ROOF
MONITOR6
9.6
no data
no data
no data
no data
no data
0.79
no data
no data
PRODUCT1
48
1.4
no data
12
1
5
no data
no data
no data
a Reference 4, p. 3-183.
b Reference 8, p. 5-13.
c Reference 16, p. 39.
d Reference 6, p. 11.
e Reference 6, p. 20.
  Reference 7.
* ounces/ton

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           TABLE 8.  LEAD CONTENT OF FUGITIVE EMISSIONS FROM
     	            LEAD SMELTING OPERATIONAL AREAS*
     Operation                               Lead/Total Particulate

     Glover, MO, plant
          Ore-storage-bin area                       0.508
          Blast-furnace area                         0.498
          Sinter building                            0.275
          Background at truck-to-rail ore
            transfer point                           0.104
     East Helena, MT, plant
          Background at ore loading                  0.217
          Dross/reverberatory building               0.222
          Sinter building                        "    0.096
          Blast furnace                              0.108

     *Data is from Reference 6.

percent coke is added to the sinter which is initially 40 percent lead;  (b)
used 50 weight percent lead for fugitive emissions  from lead transfer, ladling,
and casting since furnace tapping measurements in Table 11 of Reference  6
averaged 52 percent lead; (c) eliminated slag cooling and piling from the
emissions inventory under the assumption that all slag is granulated with
negligible fugitive emissions; (d) eliminated zinc  fuming emissions from the
inventory; (e) used 25 weight percent lead for fugitive emissions from the
dressing and reverberatory furnace operations, since a measurement  of this
area was 22.2 percent; and (f) eliminated silver retorting emissions from the
inventory.
     Some size distribution data was found for fugitive emissions from lead
smelters.  Midwest Research Institute (MRI) conducted actual plant measurements
of fugitive emissions from two ASARCO primary lead  smelters:  the Glover,
Missouri plant and the East Helena, Montana plant.    Because of the measurement
problems associated with individual sources, fugitive emissions from an  entire
operation (such as the sintering building) were measured as one fugitive
source.
     MRI determined the particle size range of total particulate fugitive
emissions for four locations at the Glover plant:  (1) sintering building, (2)
blast furnace tapping area, (3) blast furnace feed  charging area, and (4) ore

                                       19

-------
storage bin area.  A Sierra, Model  230,  HiVol  cascade impactor was used.  A
Sierra impactor was also used to determine the particle size range for total
fugitive emissions from the East Helena  blast furnace operations.  The results
are summarized in Table 9.

   TABLE 9.  PARTICLE DISTRIBUTION  FOR FUGITIVE PARTICULATES FROM LEAD SMELTING*
                                  'Concentration         Particle size range
                                    o
Location                        ug/m           wt%               urn
Sinter building,
Glover, Missouri




Blast furnace tapping
operations,
Glover, Missouri



Blast furnace charge-feed
area,
Glover, Missouri



Ore-storage bin





Blast furnace operations,
East Helena, Montana




1,420
207
174
112
117
116
44.1
39
32.7
24.7
40.4
75.7
1,301
79.1
82.1
81.2
190
339
372
36.6
54.4
45.1
89.5
177
652
375
242
132
102
71.1
66.18
9.64
8.11
5.2?
5.45
5.40
17.19
15.20
12.74
9.62
15.74
29.51
62.81
3.82
3.96
3.92
9.17
16.32
48.03
4.72
7.02
5.82
11.55
22.86
41.43
23.82
15.37
8.38
6.48
4.52
<0.38
0-.38-0.71
0.71-1.15
1.15-2.3
' 2.3-5.6
>5.6
<0.31
0.31-0.59
0.59-0.95
0.95-1.9
1.9-4.6
>4.6
<0.33
0.33-0.63
0.63-1.0
1.0-2.03
2.03-4.9
>4.9
<0.31
0.31-0.59
0.59-0.95
0.95-1.9
1.9-4.6
>4.6
<0.31
0.31-0.59
0.59-0.95
0.95-1.9
1.9-4.6
>4.6
'tlata is from Reference 6.
                                        20

-------
     Particle  sizes as  determined by Harris and Drehmel    with a Brink impactor
gave the data  in Table  10  for ducted emissions from a lead sintering machine.
   TABLE  10.   PARTICLE DISTRIBUTION FOR DUCTED LEAD SINTERING MACHINES  GASES*
   Particle Size               Particle Loading            Size Distribution
                            mg/nT
            gr/scf
                          wt*
>3.1
1.8-3.1

1.25-1.8
0.62-1.25
0.38-0.62
<0.38
TOTAL
93.30
37.12
0
59.47
135.88
152.77
47.18
525.72
(0.04077)
(0.01622)

(0.02599)
(0.05938)
(0.06676).
(0.02062)
(0.22974)
17.75
7.06

11.31
25.85
29.06
8.97
100.00
   *Data is from Reference 17.

     Some idea of the size distribution of fugitive particulates outside the
                                                                 I 0
boundary of a lead smelter can be gained from data by Dorn et al.     They
measured lead, cadmium, zinc, and copper levels in suspended particulate over
winter, spring, and summer seasons at a site approximately 800 meters north  of a
lead smelter.  An eight-stage Andersen impactor sampler was used.   While they
did not present total particulate weights versus size, a rough idea of the
particles in the respirable range can be gained from the elemental  distribu-
tions in Table 11.  Complete elemental distribution data is given in Table 12.

      TABLE 11.  DISTRIBUTION OF Pb, Cd, Zn, Cu IN RESPIRABLE RANGE NEAR A
      	PRIMARY LEAD SMELTER*	
      Particle Size
          ym
Pb
Element and  Percent
       Cd           Zn
Cu
> 4.7
< 4.7
34.29
65.71
11.69
88.31
27.09
72.91
45.68
54.32
      *Data is from Reference 18.
                                        21

-------
     TABLE 12.  AIRBORNE ELEMENTAL CONCENTRATIONS  NFAR  PRIMARY LEAD SMELTER*
                                   Elemental  Concentration
Size
ym
> n
7-11
4.7-7
3.3-4.7
2.1-3.3
1.1-2.1
0.65-1.1
0.43-0.65

Pb
3
yg/m wt%
0.1064
0.0733
0.1768
0.1655
0.0691
0.1430
0.1651
0.1372
1.0361**
10.26
7.07
17.06
15.97
6.67
13.80
15.93
13.24

Cd
3
yg/m wt%
0.0009
0.0007
0.0013
0.0014
0.0011
0.0064
0.0071
0.0059
0.0248
3.63
2.82
5.24
5.65
4.44
25.81
28.62
23.79

Zn
yg/m3 wt%
0.0194
0.0113
0.0166
0.0163
0.0140
0.0307
0.0343
0.0320
0.1746
11.11
6.47
9.51
9.34
8.02
17.58
19.64
•
18.33

Cu
3
yg/m wt%
0.0042
0.0018
0.0029
0.0026
0.0015
0.0016
0.0008
0.0040
0.0194
2l'. 65
9.28
14.95
13.40
7.73
8.25
4.12
20.62

*Data is from Reference 18.
**Numbers in this column are taken as published.   Individual  values add to
   1.0364, not 1.0361 as is shown.

 COPPER  SMELTING
Process Description of Copper Smelting
     United States copper smelters vary more in their processing steps than do
lead smelters.  Broadly speaking,  (1) part of the sulfur in the ore concentrate
is burned in the roasting process, (2) the calcine produced in roasting is
melted  together with fluxes in a reverberatory furnace which produces a slag
for discard and a copper bearing "matte,"  (3) the matte is transferred to
converters into  which air is blown and iron impurities are periodically
removed as slag, and (4) blister copper from the converter is cast into anodes
which are sent to an electrolytic  refining plant.  Some plants carry out the
roasting in multihearth roasters,  other plants use fluidized beds, and some
feed the concentrate directly to the reverberatory furnace.  Newer smelting
processes are being developed—such as continuous smelting—which differ markedly
from the general  scheme described  above.   Reference 19 provides a good overview
of the .available and developing  smelting technology.   Some detailed engineering
information  on the United States plants, has  been compiled by Pacific Environ-
mental  services,  Inc.20
                                       22

-------
     Figure 2 presents a flowsheet for a copper smelter having Fluosol ids"'feed
roasting and conventional reverberatory furnaces.  A brief discussion of the
processing steps as sources of fugitive emissions follows.
     Concentrate from outdoor storage is fed to a Fluosolids roaster to remove
part of the.sulfur in the concentrate.  Feed to this roaster is via conveyor
belt and hopper.  The roaster offgases pass through primary and secondary
cyclones which remove most of the calcine and discharge it into reverberatory
furnace charging bins through a sealed system.  The roaster exhaust gases are
then scrubbed to remove most of the remaining fine particulates and the clean
exhaust gas stream joins the gas stream from the converters and reports to a
sulfuric acid plant.
     Fugitive particulate emissions from a Fluosolids roasting system are
generated mainly by material handling.  However, the other roasting process,
multihearth roasting, is not as clean.  Multihearth roasters tend to have leaks
which result in fugitive particulate emissions.
     One or more reverberatory furnaces follow the roasters.  Calcine from the
roasting step is fed to the reverberatory furnace from calcine bins through
sealed feeders which feed the furnace for approximately two out of every
fifteen minutes.  The reverberatory furnace is typically fired with natural
gas, but fuel  oil can be used.  Slag and matte are tapped from the reverb
furnace into ladles.  The reverb slag is transported to a slag dump where it is
poured to resolidify.  The copper-containing reverb matte is transferred to the
converters for additional processing.
     Furnace leakage, slag and matte tapping, and hot materials transfer are
the main sources of fugitive emissions around the reverberatory furnace.
Fugitive particulate emissions from this area are relatively small; very little
visible fugitive emissions can be seen in this area, even during the tapping
operation.
     Matte from the reverberatory furnace is transferred by overhead crane and
charged to one of several converters.  Air is blown through tuyeres into the
charge, flux is added, and the slag produced is skimmed into ladles.  The slag
is then transferred by slag hauler to cooling pits.  Water sprays in the pits
(similar to lawn sprinklers) are used to assist cooling the hot converter slag
which is finally broken by a bulldozer equipped with breaker bars.  The broken
                                        23

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1 RAILCAH OUMfING
                                                                                              ORE TO GRINDING,
                                                                                               CCMKINTHATIOM
                                                                                               AHO OEWATIfllHa
         Figure 2.  Flowsheet of Typical Copper Smelting Operations.
                                           -24

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slag is returned to the concentrator where it is reprocessed  with  raw  ore.
Offgases from the converter are collected by hoods and pass through  a  gas
cooler in which the gas stream is treated by a concurrently flowing  ultra-
sonically dispersed water spray.  The cooled gas stream flows through  high
velocity ducts to a scrubbing tower, is blended with the roaster gas stream  and
reports to an acid plant for conversion into sulfuric acid.   The finished
blister copper from the converters is poured into ladles for  transfer  by
overhead crane to an anode furnace, where it is first oxidized by  the  addition
of air and then reduced with propane or natural gas. The finished  anode copper
is poured into anode molds, cooled, and loaded onto rail cars for  shipment to
an electrolytic refinery.
     Converter operations are probably the largest single process  source of
fugitive emissions in a copper smelter.  Access requirements  and high  tempera-
tures around the converter mouth make tight hooding very difficult and there is
a good deal of fume and participate that escapes around the converter  hood and
rises to the roof monitors.  These gases are on the order of  350 to  500 °C
(600 to 930 °F).  There is an area near the converter aisle that is  used to
accumulate and recycle copper scrap; fugitive dust is generated as the crane
clam shell moves this scrap material.  While there is typically no hooding over
the mouth of the anode furnace, there are no visible fugitive emissions from
this operation.  Copper from the anode furnace is tapped into a circular
casting wheel to make anodes for electrolytic refining.  Again, no visible
fugitive emissions are seen from this operation other than steam coming from
water that is used to cool the anodes as they circulate on the wheel.  The hot
anodes are picked off the wheel and dropped into a water cooling bath, and
again, while some steam is emitted, there is no visible particulate.
     In general, aside from the copious fugitive particulates from the copper
converters, the strongest sources of visible fugitive particulates in  a smelter
are materials transfer and vehicular traffic around the plant. Traffic  includes
front-end loaders moving material for recycle, recycle slag handling,  and
general truck traffic in and out of the area.  Some localized sources  such as
conveyor transfer points also generate fugitive particulates  on a  small scale.
                                        25

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 Fugitive  Emission Rate Data for Copper Smelting
                                                              3
      The  sample fugitive emissions inventory prepared  by PEDCo  was  used  as  the
 basis for estimating fugitive emissions from a copper  smelter producing 100,000
 metric tons per year of crude copper.   The following adjustments in  the PEDCo
 table were made to obtain the emission rates shown  in  Table  3:  (a)  roaster
 charging, a fairly large source was omitted because of its declining use  and
 the  small amount of fugitive emissions from the alternatives--greenfeed
 reverberatory charging and Fluosolids  roasting; (b) an additional  40 percent
 was  added to the process fugitive emissions to account for resuspended par-
 ticulates, the 40 percent being the same relative amount of  total  particulate
 as was used for lead smelting in Table 2.
      No sampling of fugitive emissions in copper smelters has been'done which
 compares  in scope to the MRI sampling   of lead smelter fugitive  emissions.
 EPA  is currently doing some sampling of copper smelter fugitive  emissions
                               22
 through a contract to TRW, Inc.    Several  operations  are being  sampled for
 fugitive  emissions with the main emphasis being on  fugitive  arsenic  emissions.
 However,  total particulate levels are  being measured on some of  the  samples.
 Fugitive  Emission Size and Composition Data for Copper Smelting
      The  composition data used to obtain the elemental  lead  emission rates  in
 Table 3 are discussed below. The lead  content of fugitive particulate emissions
 from copper smelting is much lower than the lead content of  fugitive emissions
 from lead smelting.  The elemental lead emission rate  is far lower for copper
 smelting.  However, other trace metals such as arsenic may be concentrated  in
 some fugitive streams from the copper  smelter. Information on the concentration
 of metals other than lead are presented, where available, but estimates of
 overall rates for elements besides lead were not made.
      Fugitive emissions from material  handling of copper concentrate will have
metal contents similar to the concentrate itself.   There is  substantial varia-
 tion in metals content depending on concentrate source.  In  particular, lead
 varies from around 50 ppm to over 10 percent.  Table 13 shows the minimum,
                                                                          23
maximum,  and production-weighted mean  values for U.S.  copper concentrates.
 The  production-weighted mean lead content of 1.67 weight percent was used in
 the  fugitive emissions inventory in Table 3.  Fugitive emissions from concentrate
 storage and handling are the largest single source  of  elemental  lead in the

                                        26

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Inventory.  It is recognized that lead contents vary widely between  smelters
and lead emissions may be orders of magnitude lower for some smelters.

      TABLE 13.  COMPOSITION OF COPPER CONCENTRATES PROCESSED IN THE U.S.
     Metal
Minimum
Composition,  Weight  Percent
                 Mean as weighted by
Maximum      -     1971 production
Cu
Pb
S
As
Sb
Bi
Zn
Sn
Ni
Se
13.8
0.005
22.8
0.0007
' 0.0002
0.005
0.02
0.0003
0.0005
0.0005
36.1
13.2
44.8
12.6
3.26
0.83
12.2
0.1 "
2.4
0.095
26.9
1.67
32.0
0.97
0.10
0.024
1.49
0.0044
0.024
0.0079
     For other areas  in the copper smelter, perhaps the best indication of the
relative concentrations comes from some NIOSH sampling results.   Between 1965
and 1973 NIOSH collected data throughout the copper industry on  trace metal
levels in smelters.    Samples from many smelters were obtained  and used to  get
long term, industry-wide averages of exposure for the following  smelter areas:
(a) reverberatory furnace charging deck; (b) reverberatory furnace operators
deck; (c) converters; and (d) anode casting.  Both personnel and area samples
were collected.  Membrane filters with a 0.8 micron size were used to collect
metal fumes and dusts which were then analyzed by atomic absorption.   Unfor-
tunately, total particulate levels are not given for the various areas, only
ambient elemental concentrations.  Table 14 summarizes the NIOSH data.
     Some composition data for ducted particulate from the Bor,  Yugoslavia
copper smelter is given in Table 15.  The lead contents for the  particulate
streams in the U.S. probably averages higher than those for Bor  because of the
                                        27

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              TABLE 14.   ELEMENTAL CONCENTRATIONS IN AIR BY COPPER SMELTER AREA. INDUSTRY-WIDE AVERAGES*

                                                            3                                             3
          Area                           Area Sampling, mg/m                      Personnel sampling, mg/m

                                  Pb     Zn    Cu    As     Cd      Mo     Pb     Zn    Cu     As      Cd      Mo
          i        -...--	._      • _ - *            ......	_ .-  ->_.^>—._.....-- i v >»—a—r 11- i - *i •.-•.>.	

          Reverberatory           0.07    0.07  1.1    0.04  0.005  0.014    0.07  0.12  3.4  ND**  0.005   0.003
            furnace
            charging deck

          Reverberatory           0.06    0.12  2.3    0.02  0.012  0.015    0.07  0.07  1.3  ND    0.006   0.03
            furnace
            operators deck

          Converter aisle        0.05    0.05  0.22   0.01  0.003  0.004    0.03  0.04  0.11 ND    0.004   ND
(M
00
          Anode  casting           0.01   <0.01  0.13  <0.01  0.001  ND       0.01  0.01  0.07 ND   <0.001   ND


          **ND = No Data

           *Data from Reference 24

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               TABLE 15.  COMPOSITION OF DUCTED COPPER CONVERTER DUSTS FROM BOR. YUGOSLAVIA25
Composition, Weight Percent
El ement
Cu
Pb
Fe
S
Mo
Se
As
Typical
concentrate
16
0.1
32
42
0.005
0.003
0.5
Converter dust from
Matte slag blowing
38.50
0.2785
32.04
25.80
0.0044
0.0275
0.1907
42.0
0.5914
12.05
11.82
0.0130
0.0325
1.1173
Converter dust from
copper blowing
58.26
0.8984
5.26
14.01
0.0055
0.0334
1.0783
Reverberatory
furnace
13
0.5
17
NO*
0.02
0.003
2.0
^        *No Data
LD

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higher average concentrate lead content  In  the  U.S.--1.67 versus 0.5  percent.
To convert the NIOSH data into participate  composition, the copper  content  of
the participate from each sample would  be  needed.  As  this is  not provided,  it
is instead assumed, based on the Bor data,  that typical copper contents  are  40
percent in particulate from the converter  and anode areas and  15 percent in
particulate from the reverberatory area. This was done and gave the estimated
compositions in Table 16.  Based on Table  16, the following lead contents were
used to prepare Table 3: for charging and  tapping of the reverberatory furnace,
1.5 weight percent lead; for converter charging and leakage, 2.0 weight  percent
lead; and for charging blister copper and  anode furnace tapping and casting,
1.0 weight percent lead.
     Little size data is available for fugitive particulate emissions from
copper smelters.   In an attempt to distinguish  between "respirable" and  "non-
respirable" metal  concentrations, the NIOSH workers took some  samples through  a
cyclone before analyzing for metals collected on the filter; the range for
respirable particle size is not given.  Table  17 shows the results  for .23 data
points for converter furnace and crane aisle employees.  Harris and Drehmel
provided the values in Table 18 for ducted particulates from a copper converter
as sampled by a Brink, Model B, five-stage impactor.
                         p£
     Thompson and  Nichols   measured ducted particulates from  two copper rever-
beratory furnaces  with cascade  inertial impactors  and  five-stage cyclones.
Data estimated from two figures they provided  are given in Table 19.
                                        30

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     TABLE 16:  ESTIMATED COMPOSITION OF FUGITIVE PARTICULATES BY COPPPER SMELTER AREA3

Area                               Area Sampling                    Personnel  Sampling

                         Pb    Zn    Cu    As     Cd    Mo       Pb    Zn     Cu     As     Cd    Mo


Reverberatory           2.5   2.5   40b   1.4    0.18  0.51     0.82   1.4    40b     ND** 0.06   0.04
   furnace
   charging deck                      ,                                      .
Reverberatory           1.0   2.1   40°   0.35  0.21  0.26     2.2   2.2    40°     ND   0.18   0.92
   furnace
   operators deck

Converter aisle         3.4   3.4   15b   0.68  0.20  0.27     1.4   1.8    15b     ND   0.18   ND

Anode casting           1.2  <1.2   15b  <1.2   <0.12   ND      0.71   0.71   15b     ND   <0.07   ND

**ND = No Data
Elemental concentration data from Reference 24 converted  to weight percent by assuming forty
 percent copper in particulates from reverberatory furnace  areas and fifteen percent copper
 in particulates from the converter and anode  casting areas.

 Assumed

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  TABLE 17.  PERCENT OF METAL AEROSOLS IN RESPIRABLE9 RANGE: CONVERTER,  FURNACE
             .AND CRANE AISLE EMPLOYEES IN U.S. COPPER SMELTERS	
     Metal
                Pb
                Zn
             Cu
             As
             Cd
Average %c Respirable
          52.1
          59.5
        6.1
       75.2
       49.5
aNo size given for "respirable."  Larger aerosols were removed using  a
 miniature cyclone before collecting remainder on a filter.
 Data adapted from Reference 24.
C23 data points each, except As only has 14.
  TABLE  18.   PARTICLE  DISTRIBUTION  FOR  DUCTED  COPPER  CONVERTER GASES
  f~T -J J - , iTlm. _JI - -------  — 	-"       ~      	   -•--.— -:	  . -•	'"•'—' -^-JTJIE-—"-•--•-"-m.—•--	nr  ...........   	   ._.. ..- ^-.

                              Test  1                         Test 2
Particle Size
    vim
mg/nf
gr/scf
wtl
mg/nT
gr/scf
wt%
>3.1
1.8 - 3.1
1.25 - 1.8
0.62 - 1.25
0.38 - 0.62
<0.38
TOTAL
3.52
13.59
57.02
222.04
16.36
12.58
325.11
(0.00154)
(0.00594)
(0.02492)
(0.09703)
(0.00715)
(0.00550)
(0.14208)
1.08
4.18
17.54
68.30
5.03
3.87
100.00
10.23
15.10
56.09
137.03
42.95
4.71
266.11
(0.00447}
(0.00660)
(0.02451)
(0.05988)
(0.01877)
(0.00206)
(0.11629)
3.84
5.68
21.08
51.49
16.14
1.77
100.00
 TABLE  1-9.   PARTICLE  DISTRIBUTION  FOR  DUCTED  COPPER  REVERBERATORY FURNACE GASES'
                                         PLANT A                    PLANT B
 Particle Size
                                 mg/acm
                              wt%
                              mg/acm
                                    wt%
> 4
2-4
1-2
0.6-1
0:3.0.6
<0.3
10
20
31
27
24
28
7
14
22
20
17
20
80
50
40
38
65
17
28
17
14
13
22
6
                                    32

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           4.0  CHARGED FOG SPRAYS  FOR  CONTROLLING  FUGITIVE  EMISSIONS

     This section describes charged fog spray  devices, discusses  theoretical
and experimental efficiencies  for sprays,  and"presents the efficiency  and costs
used as the basis for evaluating  charged fog sprays.
DESCRIPTION OF CHARGED FOG SPRAY  DEVICE
     The spray of fine water droplets is a well-known means  of  dust  removal.
The various types of scrubbers rely on  water droplets to  sweep  dust  from the
inlet gases, and water sprays  have  often been  used  in mining and  material
handling to reduce dust levels in the air.  Charged fog sprays, as evaluated  in
this report, differ from conventional water sprays  in that the  droplets  carry a
charge of static electricity.   Also, the droplets used for an electrostatic
spray may be of a finer size.   Since most  fine particulates  carry a  natural
                  28
electrical charge,   particle  collection can be improved  via electrostatic
attraction if the water spray  droplets  are charged  to the opposite polarity.
The charged water droplets then exert attractive forces on the  oppositely
charged particles and each droplet  collects more particles as it  travels through
the dust-laden gas.
     The water droplets in a spray  may  be  electrostatically  charged  by several   .
methods.  Droplets may be charged via induction from a metal ring surrounding
the spray (Figure 3a), via a charged needle in the  spray  (Figure  3b),  or by
direct electrical contact with the  water (Figure 3c).  In the third  case, the
spray nozzle must be insulated in such  a way as to  prevent current leakage
                                                            28
through the support structure  or  the water feedline.  Hoenig   mentions  isolating
up to 20kV by injecting air into  a  plastic tubing feedline.   The  injected air
breaks the continuous water column  into segments and prevents electrical
                                                         29
leakage via conduction through the  water column.  Hassler   has reported an
autogenous charging method which  does not  require any voltage source.   Droplet
charges result from water-to-metal  friction in a grounded spray nozzle (Figure
3d).  While not requiring any  voltage source,  the method  does require  very
pure, deionized water.  Autogenous  charging will work only  if the nozzle

                                       33

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         Water
        Feedline
 Insulated
Metal Ring
                                 5-10KV.
                                  - Charge
                       3a. Charge Induced Via Metal Ring.
                                                                  •f Cliarged
                                                              '. \  Droplets
       Water
      Feedline
        5-1OKV
        + Charge     Electrically
                     Isolated
                      Needle
                                        Spray
                                       .Nozzle

                          3b. Charging Via Needle.
                                                             ijllli'  '• "•;.  + Charged
                                                                  ••.' >V;j   Droplets
    Plastic Water
      Feedline
         Insulated
          Spray
          Nozzle
                            Air Injected J
                            to Segment
                          Water Column
                                          5-1 OKV
                                          + Charge

                    3c. Direct Contact Water Charging.
  Feedline for
De-Ionized Water
            Grounded
             Spray
            Nozzle
                                                                        '.-..  + Charged
                                                                        'j.v'.  Droplets
                                                                                   •' •'  + Charged
                                                                                   •;'    Droplets
               3d.  Autogenous Charging to De-ionized Water
                 Figure 3. Means of Producing a Charged Water Spray.
                                                         34

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is grounded and the water acts as  an  insulator;  even  tap water  has  too  many
impurities to produce a charged spray by  this means.
     The only known commercial version of an charged  fog spray  device  is  the
Electrostatic Fogger r^manufactured  by Ransburg Electrostatic  Equipment,   a
division of Ransburg Corporation,  Indianapolis,  Indiana.  The original  work on
the charged fog sprays was done by Dr. Stuart Hoenig  at the  University  of
Arizona under support provided by  the American  Foundry Society.   Dr. Hoenig
approached Ransburg and discussed  the possibility of  Ransburg manufacturing the
Electrostatic Fogger.  Ransburg as a  company has filed application  for  a  patent
on the electrostatic fogging principle, and this patent is now  pending.  Ransburg
has recently begun to commercially market the Electrostatic  Fogger  I.   Their
prior experience has been with electrostatic paint "spraying  equipmen-t.
     The following information was obtained during discussions  with Ransburg.
     The device functions by applying a 5 to 10 kilovolt induced  voltage  on a
metal ring surrounding the spray nozzle.  This changing technique  is the subject
of a U.S. Patent*.  The droplets coming out the nozzle charge either positively
or negatively as controlled by connections in the control box.  The Fogger does
not permit variation of the voltage applied to  the metal ring other than  polarity.
The control box for the Fogger is  mounted separately  from the spray nozzle
itself.  It contains a 40 micron filter on the  water  supply  and a pressure
regulator to maintain constant water supply pressure  to the  nozzle. Likewise
on the air supply to the box there is a 10 micron filter and a  pressure regulator.
The box contains an indicator light which will  dim when the  voltage to  the
spray nozzle is not high enough for one reason  or another.   It  also has a light
which indicates when the unit itself has  power.   Each spray  has its own control
box, although Ransburg can arrange to put multiple boxes  inside one larger
cabinet.  They like the approach of individual  control boxes from the  standpoint
that the entire water spray network is not dependent  on any  single  component.
Electrical requirments are SOW of 115V, 60Hz.
     Ransburg said the droplet size from  the  Fogger I is  typically 25  to 75
microns, but did not provide any further  data on the  droplet size distribution.
*During report preparation (12/78), it was  found that Ransburg had sold all
 market rights, patents, and manufacturing  equipment for the Electrostatic
 Fogger to Ritten Corporation Ltd., 40 Rittenhouse Place, Ardmore, Pa.

                                         35

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The spray device  itself  is  a  fairly  simple looking item consisting of a nozzle
surrounded by  the metal  ring  with  a  plastic case about the device.  Air provided
to the nozzle  is  used mostly  to atomize the water with a small  amount injected
tangentially into the ring  around  the  spray to produce a coanda effect (that
is, a swirling airflow around the  spray) and project the water droplets farther
than would otherwise be  obtained.  Air requirements are up to 13 SCFM at 110
psig.  The Fogger I provides  a water stream which is indeed a "fog" and not a
mist or a spray.  Typically the water  droplets evaporate 2.5-3 meters (4-6
feet) from the spray nozzle and the  width of the spray is about 0.7 meters (2
feet).
     The particular Fogger  I  which is  now being marketed by Ransburg is not
approved for use  in hazardous atmospheres.  However, Ransburg has some patented
technology in  the way of safety equipment whith can be used to make these high
voltage devices sparkproof.   The company has manufactured paint sprayers approved
for NFPA Class 1, Division  D  uses  (applications with hydrocarbon solvents used
in spray painting).  This feature  is provided by using a high resistance element
in the charging circuit  which limits the steady state current flow and by
keeping the mass  (and thus  the capacitance) downstream of this  resistor very
small.
     Ransburg  is  currently  developing  a second electrostatic fog spray to be
called Fogger  II, which  will  be of much larger capacity.  Fogger I is rated for
    O                                                                        O
16cm s (0.25 gpm) of water.   The Fogger II is being designed for up to 190 cm s
(3 gpm) of applied water and  up to 10  meters (30 feet) spray distance.  The
larger flow version of the  Fogger will not have as small a droplet distribution
as the Fogger  I.  The water droplets in it are also charged with a metallic
ring surrounding  the spray  nozzle, but the Fogger II will use hydraulic atomi-
zation as opposed to air atomization used in the Fogger I.  With the much
higher spray rates in the Fogger II, air usage would be excessive using air
atomization in some applications.  However, it will permit an air source to
produce the coanda effect if  needed  to project the spray farther.  In the
Fogger II, the control  box  will include an integral pump to provide the high
pressures of 500  psi required  for hydraulic atomization of the water spray.
                                        36

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COLLECTION EFFICIENCY OF CHARGED  FOG  SPRAYS  '  •
     Two areas important in evaluating  sprays  are collection  efficiency  and
droplet evaporation; several  studies  have  been made  in both areas.   Some of  the
more advanced treatments of single  droplet collection of dusts  have  been in  the
field of meteorology concerning the scavenging of airborne dusts  by  rain
      31 35
drops.       Droplet evaporation  has-  been  treated by researchers  in  combus-
    qc qy                  OQ on
tion  '   and spray drying.  '    (Spray drying  is the production of dry powder
                                              39
by spraying a solution into warm  gas.)  Masters   discusses not only droplet
evaporation, but also types of spray  nozzles,  droplet trajectories,  and  the
effect of suspended or dissolved  solids in the spray.  An overview of the
theory of charged droplet collections follows; for a more detailed discussion,
see the reports by Melcher and Sachar.   '
     For a single water droplet and a single dust particle, there are several
forces acting simultaneously that affect the likelihood of particle  capture.
Fairly good theories exist which  can  predict how the various  forces  affect the
efficiency of dust collection for well-controlled experimental  conditions.  In
a practical application, the theories are  less useful; operating  conditions
vary, and it is very hard to choose representative values for many of the
parameters in the theories—dust  composition,  loading, size,  and  charge; spray
size and charge; ambient temperature  and humidity; etc.
     This work approaches the problem of applying theory to practical cases  by
(a) briefly discussing the different  collection  mechanisms and  their relative
magnitudes, (b) presenting some theoretical predictions of the  effect of electro-
static charge on collection efficiency, and  (c)  showing how droplet  evaporation
and water application rate should affect efficiency  of dust removal.  Thus,  the
emphasis is on using the theory to get  directional trends rather  than absolute
values.
Impacti on/Intercept! on
     These collection mechanisms  are  closely related and are  the  dominant
forces in collecting larger particles with water sprays.  When  a  droplet and a
particle approach each other on a collision  path, the particle  tends to follow
the fluid -streamlines and be swept around  the  larger droplet.  Because of its
                                        37

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Inertia, however, the particle does not exactly follow the fluid path, but
instead cuts across some  streamlines.  Depending on the initial  trajectory and
velocity, it may impact directly on the droplet (Figure 4a), barely graze the
droplet (Figure 4b) or entirely miss the droplet (Figure 4c).   The "direct-hit"
collection of very small  particles is termed impact!on, while  interception
refers to the grazing trajectory of larger particles.  The collision efficiency
(i.e., the fraction of area swept clean of particles by a water droplet)  is
improved by increasing the relative velocities between droplet and particle,
increasing the particle diameter, and increasing particle density.
Diffusion
     Particles of submicron size, and thus low inertia, are rarely captured by
impaction/interception because they follow the gas streamlines around the
particles.  However, some of the very small particles are captured as they move
past a droplet because they diffuse to the droplet surface via the random
bombardment by gas molecules.  This collection mechanism is termed diffusion
and is improved with decreasing particle size.  For particles  one micron  or
larger, this mechanism is negligible.
Phoresis
     Phoresis is the process in which particles move because they are subjected
to a gradient in temperature (thermophoresis) or vapor pressure (diffusiophoresis)
If a liquid is evaporating at one surface and being absorbed at another parallel
surface (Figure 5a) and there is no temperature gradient, the  particles will
experience a net force in the direction of vapor molecule movement.  Similarly,
if one parallel plate is  kept hotter than the other, the more  frequent gas
collisions on the hotter  side of the particle will force the particle toward
the cooler plate (Figure  5b).
     Phoretic forces are  not very strong compared to the other collection
forces for particles larger than two or three microns.  For the particular case
of submicron particles around an evaporating water droplet, phoretic effects
become significant.  However, their net effect depends on the  ambient humidity,
the droplet temperature,  and the ambient temperature, and many researchers
neglect one or both of these forces.
                                       38

-------
            Fluid Streamlines
 Particle
  Path
                        Figure 4a.  Path for Direct Impaction of Pnrticie.
Particle Path  ->  —  —  —  — —
Direction of
    Flow     -y	
                       Figure 4b. Path for Limit of Interception of Particle.
          Particle Path
                       Figure 4c. Path for Particle Not Collected by Droplet.
                       Figure 4. Particle Trajectories Around a Water Droplet.
                                            39

-------
                          FiIter Paper Moistened With H2S
Temperature      t I t j  f t  t t      'ttfft'Mtt
                                                                             Particle Path
                        Filter Paper Moistened With Pure Water
                                                                            /  Air Flow
                        Figure 5a.  Diffusiophoresis in Isothermal System,
                            Plate Held at High Temperature
>l
Heat Flo
1 I \
HI
( I
, Air Flow
e <
^ — """"" Particle Path
                           Plate Held at Low Temperature
                      5b. Thermophoresis Due to Temperature Gradient.
               Figure 5.  Thermophoretic and Diffusiophoretic Forces.
                                               40

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Electrostatic Attraction
     Practically all  aerosols  carry  an  electrical charge.  The  presence  of
charge on the particle  or the  droplet  (or  both) affects the  particle  trajectory
around the droplet and  can improve  (opposite  charges) or reduce  (alike charges)
the collection efficiency.  The interacting forces  increase  as  charges in-
crease.
     The maximum charge a droplet can  carry (termed the Rayleigh  limit)  is
reached when the mutual repulsion of the charges accumulated on  its surface
equals the surface tension holding  the  droplet  together.  The Rayleigh limit  is
typically reached for evaporating droplets.   At the Rayleigh limit, evaporating
droplets eject smaller  charge-carrying  droplets to  dispose of excess  charges.
The Rayleigh limit on water droplet  charging  is shown in Figure  6--for 100 m
                                        - 7                     12
diameter droplets, this limit  is about  5X10 e per droplet (8x10    coulomb).
     For a solid particle, the maximum  charge is limited by  the  point where
ions or electrons are spontaneously  emitted from the surface. However, this
limit is rarely approached. Several workers  have reported the  average charge
of all the particles in a dust sample  to be 5 to 20 electron units  (e) positive
                  -19           29  42  44
per particle (8x10    coulombs). J>^»^   Not all particles  are  positively
charged, however.  There is a  distribution of both  positively and negatively
charged particles within the dust sample as is  schematically shown  in Figure  7.
     Thus far, four collection mechanisms--impaction/interception,  diffusion,
phoresis, and electrostatic attraction—have  been highlighted.   The expected
electrical charges on droplets and  particles  has also been discussed.  How can
this information be applied to the  case of interest—reduction  of large  scale
emissions of fugitive particulates  from smelters?   In an industrial appli-
cation, the water spray droplets are charged  and projected into  the dusty gas
stream.  As the water droplets travel  through the particulate cloud,  they
capture dust particles, and finally, the droplets settle out of the gas  stream.
Small particles which would otherwise  remain  suspended  will  settle  out because
they have either become attached to  the larger  water droplets or agglomerated
                                    35
with other particles.  Grover  et al.   determined the collision  efficiency of a
droplet/particle pair for the  case  of  water droplets falling at their terminal
velocity.  They calculated several  cases while  varying  droplet  size,  humidity,
                                       41

-------
 a
 '5
•S
1
I09
  5
  2
I08
  i

  2
!07
  5
  2
10s
  5
  2
IOJ
  F
  2
I04
  5
    10;
                     i   r
Rayleigh Limit
for Water
(Surface Tension
= 72 Dynes/cm)
                 I
    I    I
                            I	I
I    I     I
      O.I  0.2 0.5
       2_   5  10  20  50 100
       Particle Diameter, Mm
                                               500 1000
             Figure 6. Limiting Charge for Water Droplets.

-------
                                      NEUTRAL
                                          0
                                                 POSITIVE-
                                                 CHARGE
                                                      AVERAGE CHARGE IS
                                                      TYPICALLY 5-20e
                                                          POSITIVE
a
                                       NEUTRAL
                                           0
                     Figure 7. Typical Charge Distribution for Micron Size Particles.
                                           43

-------
electric charge,  etc.   Cross-plots  showing the effects of several  variables are
seen in Figure  8.   This data  can  ultimately be used to calculate overall
collection efficiency  of a  spray.
     At first glance,  the data in Figure 8 appears overwhelming, but on closer
inspection several  important  conclusions can be abstracted.
     Figure 8a  shows how the  collision  efficiency is strongly dependent on
particle diameter,  decreasing from  nearly 1.0 for 100 ym particles to a minimum
value of about  0.001 for particles  2-3  ym in diameter.  This minimum in the
collision efficiency curve  implies  particles in the 2-3 pm size range, as are
commonly found  in  smelters, will  be much more difficult to collect than the
larger particles.   Notice also that for any given size particle, water droplet
size influences the collision efficiency.  Larger" droplets tend to-be more
effective for larger particles, while finer droplets are more effective for the
subtnicron particles.
     Figure 8b  depicts  how  the ambient  relative humidity (or equivalently, the
tendency of the droplets to evaporate)  affects the collision efficiency.  For
particles larger  than  about 3 microns,  humidity has little effect, but for
finer particles,  drier  environments theoretically improve the collision
efficiency.  In a  real  situation, the shorter droplet lifetimes at higher
evaporation rates  might override  the collision efficiency improvements.
     The most pertinent information in  Figure 8 is that shown in Figure 8c—the
effect of electrostatic charge on collision efficiency.
     First, some  background on the  assumptions used to calculate Figure 8c.
                    35
Grover and coworkers    solved the problem in which the droplet and the particle
have equal, but opposite, charges.  The total charge on a droplet (or particle)
was assumed to  increase proportionately with surface area.  They calculated
                                                                 2
three cases: (a) no static charges  present; (b) Q droplet = +0.2a ,  Q particle
      2
= 2.Or  (where Q  is charge expressed in esu, a is the drop radius in centi-
meters and r is the particle  radius in  centimeters); and (c) Q droplet =
     2                    2
+2.0a , Q particle  = 0.2r  .   A fourth efficiency curve is shown which was
                                    45
calculated by a less rigorous  method    to give a rough idea of the curve for Q
             2                      2
droplet = 20a  and  Q particle  = 20r .   For particle sizes typical  in smelting
                                        44

-------
5
2
10-1
1; 5
|
— 2
1 10-2
3
1 5
i
i
J
io-3
5

2
io-4
X^'
/'/ft''
/

OHOPLET
DIAMETER, p;m 1
- """N
\
M
**•«. 'f
x M
212— \ \\
""NjJ/
346-,^ Y/
sis-"""

i i 1 <
i —
-

•
_

-
No tlMTrBiralic cnargt
73% ralotivt tumidity
IQ'C amei«or T
_
-

-
1 , !
O.I  0.2   O.S  1.0  2    S   10   20   50  100
             Piftiele OiifiHiir, ym


 Figure 8a.  Effect of Droplet Diameter


     on Collision Efficiency,
                                        O.I  0,2   0.5  1.0  2     5   10  20   50  100
                                                       Particli Oiamim. ^n


                                        Figure 8b.  Effect of Relative Humidity


                                               on Collision Efficiency.
                                   10°


                                     i


                                     2


                                   10-'


                                -    5
                                S
3    5



t    2

    10


     5
       ELECTROSTATIC CHAHCE
                                                           212/im wottr dn?0l«1

                                                                rvlotiv* humkJtty

                                                            IO°C  ombitiit T
                                     Ql  0.2   0.5   1.0   2    5  10  20   50  100
                                                   Pirricii Oiimnif, ^n


                                    Figure 8c. Effect of Electrostatic Charge


                                            on Collision Efficiency.
                      Figure 8.  Effects of Particle Size, Droplet Size, Relative  Humidity,
                               and Electrostatic Charge on  Collision Efficiency.

-------
applications  (3 micron  particles and 200 micron droplets)  and for a  particle  of
                                                                           g
average excess charge  (lOe) and a water droplet at its Rayleigh limit (2x10 e),
it is estimated that the  collision efficiency curve will  lie between the Q =
    2                2
2.Or  and the Q = 20r   curves  in Figure 8c.
     Disregarding the details  of the assumptions made, and the variations due'
to size, there are two  broad conclusions that are apparent from Figure 8c.
First, the presence of  electrostatic charges increases the collision efficiency.
for all size particles  and eliminates the minimum around  2 microns.   Secondly,
charged sprays in industrial applications would have collision efficiencies
roughly 5-10 times higher than uncharged sprays.  Caution:  these collision
efficiencies are for single droplets only, they do not indicate that the
overall collection of dusts by a spray will be 5-10 times  higher. The rela-
tionship between single droplet collision efficiency and  overall  collection
efficiency is presented next.
     A relationship is  needed  between the collision efficiency and the other
important variables such  as flow rate, spray rate, system  geometry,  etc.  In  a
                                              46
paper on suppressing airborne  coal dust, Cheng   presents  such a relationship
for overall efficiency  of a water spray on a dust cloud:
          Eo • i - ^ir1'  of   •

          where E  = overall number of dust particles
                     collected by the spray
                  = single droplet collision efficiency as
                     discussed above
                D  = droplet diameter
                Qw = water flowrate
                Qg = gas flowrate
                L  = a characteristic length which measures  the length
                     of the spray trajectory through the gas.
                                         46

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     Equation 1  is obviously only an idealized version  of the complex inter-
action between a spray and a moving dust cloud, but the form of the equation is
instructive.   By rearranging, it is seen that log 1/(1-E )  is directly pro-
portional to  n and to Q water, and inversely proportional  to Q gas if the
droplet size  and spray geometry are constant.  These relationships together
with Figure 8 can be used to predict charged spray efficiencies from experi-
mental results for uncharged commercial  sprays.
BASIS OF COLLECTION EFFICIENCY FOR COMMERCIAL DEVICES
     Much of  the experimental measurement of fine particulate removal by water
sprays has been done by researchers attempting to reduce the level of res-
pi rable dusts in underground coal mines.    Uncharged sprays reportedly reduce
respirable dust 20 to 60 percent with 30 percent seeming to be an average
      48
value.    Extrapolating 30 percent efficiency assuming  equivalent geometry,
water rate, and droplet sizes, a charged fog spray with a five times higher
single droplet collision efficiency would remove about  80 percent of the
respirable dust.  Practically, the charged fog efficiency would not be as high
because of much lower water application rates for charged fog sprays compared
to conventional  sprays.              I
     Lab scale experiments and limited commercial applications of charged fog
                         28
sprays as cited by Hoenig   mostly range between 50 to  80 percent collection
efficiency.  This agrees well with the above analysis.
     There is an important limitation on the charged fog spray applications
cited so far—they have been in enclosed areas or on applications in moderately
still air.  Spray performance would not be anticipated  to be very good for
highly turbulent air streams as are often encountered in smelting.  The reasoning
follows.
     The critical parameter in spray performance is the ratio of the spray rate
to the volume of gas treated.  For still air or confined spaces, the water
droplets settle through the gas and collect and agglomerate particles.  All
together, the water from one small spray may be distributed through 2-4 m
                    o
of volume (30-100 ft ).  In an open, highly turbulent situation, both the dust
particles and the water droplets would be dispersed outward and become more and
more diluted  into larger and larger volumes of gas.  The effective volume of
gas that must be treated is no longer just confined to the area around the
                                       47


-------
2          5       10     20        50     100   200      500    1000
                     Initial Droplet Diameter, Mm

 Figure 9. Lifetime of Water Droplets Traveling at Their Terminal Velocity.
                                  48

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spray, but also  includes  the  entire  area of turbulence  which  is  greater by
maybe a factor of 1,000  since volume goes up with the cube of distance.  (That
is, if instead of being  dispersed  three feet, turbulence  disperses  the particles
                                                       3            3
and droplets  thirty feet,  the gas  volume goes from 9 ft  to 9000 ft .)  A
second factor must also  be cosidered in open, turbulent environments.   When the
water droplets that do collect particles eventually settle out of the  air, the
particulate will  be spread over a  large area and in a sense,  not be "collected"
at all.
     A simplifying assumption in the above analyses has been  that of no droplet
evaporation.   When sprayed into air, the small droplets formed by a charged fog
device will evaporate unless  the ambient air is saturated with water.   In most
cases of practical  concern, the air  is not saturated, and a droplet will
completely evaporate after a  certain period.  The droplet lifetime determines
the effective contact time between the spray and the dust-laden stream, and
thus strongly impacts on the  overall spray efficiency-  (a short lifetime droplet
will disappear before collecting very many-dust particles. Some work with
charged fog sprays in high temperature enclosed systems is being done  by Dr.
Hoenig at the University of Arizona  at Tucson, but at this time the under-
standing of the  data is  incomplete.
     The temperature and humidity of the ambient air are the two main variables
affecting evaporation rate.  When a  droplet evaporates  two simultaneous pro-
cesses occur—heat flows toward the  droplet from the surrounding air and water
vapor molecules  diffuse  away from the droplet surface into the surrounding air.
High ambient  temperature increases heat flow to the droplet and hastens evapora-
tion, while low  ambient  humidity increases the rate of evaporation by  speeding
the diffusion of water vapor molecules away from the droplet surface.
     Figure 9 depicts water droplet  lifetime versus droplet diameter for three
cases of practical significance: (a) 20°C (68°F), dry air which represents a
plant compressed air supply;  (b) 27°C (80.6°F) air with a relative humidity of
90 percent which represents a warm,  moist environment;  and (c) 179 C  (388  F)",
dry air which represents the severe  conditions around a copper converter or
furnace taphole.  Notice how, for a  200 ym droplet, the lifetime is of the
order of 0.1  second for the high temperature  (170°C) conditions.   During such a
short lifetime,  the droplets can neither travel very far, nor encounter very
many dust particles, and correspondingly poor dust collection would be expected
under such conditions.  Indeed, a 100 ym drop falling at  its terminal  velocity
in dry 170°C  air will only travel  7  cm  (3 in.) before evaporating.
                                        49

-------
     Summarizing  the  discussions of this section:  (a) while for uncharged
sprays, there  is  a minimum  in  the collection efficiency for about two micron
diameter particles, there is not any such minimum for charged sparys  and  some
improvement or collection of respirable dust is expected from charging;  (b) the
charged fog sprays are  best suited to localized sources of dust, suspended  in  a
low velocity or stationary  gas stream; (c) the combination of high temperatures
and excessive  gas turbulance rule out charged fog sprays for areas such  as
copper converter  leakage or furnace taphole emission control; and (d) at
reasonable water  application rates, the charged fog sprays are unlikely  to  have
efficiencies approaching 90 percent—overall collection efficiencies  on  the
order of 60 percent are more likely.
COST DATA AND  UTILITY CONSUMPTION FOR CHARGED FOG~SPRAYS
     The total  erected  cost for a charged fog spray device consists of:   (a)
purchased equipment cost; (b)  installation materials; (c) installation labor;
(d) auxliary equipment  costs;  and (e) indirect costs.  The estimates  for  each
category are further  discussed below—bases, assumptions, and cost data.  Table
20 summarizes  the cost  calculations.
     The charged  fog  sprays themselves are the largest component of purchased
equipment cost.   A small charged fog spray, having a coverage area of approxi-
mately 2 ft by 6  ft,  is sold for $2,000.30  This includes 50 ft of air hose,
water hose, and shielded high  voltage cable, and does not include any quantity
discount which  may be available for purchasing several devices.  We have
assumed a 25 percent  discount  for buying a large number of spray units,  making
the estimated  price for one unit $1 ,500.
     A larger  scale charged fog device under development, which has a coverage
area of approximately 6 ft  by  20 ft has not been commercialized and no sales
price is available.   Often, prices are extrapolated from one capacity to  another
using the "0.6  power  rule," but since costs for the electrical equipment  and
spray nozzle for  a charged  fog  device are fairly independent of size, a  smaller
exponent is appropriate for the cost-capacity equation.  An exponent  of  0.1
                                                                        4-Q
is typical  for  conventional  spray nozzles in the size range of interest.    An
exponent of 0.2 was used to prorate the costs of the smaller device:   Cost  of
                      2                    2               02
large spray =  (120 ft   coverage area/12 ft  coverage area)    x ($1,500  cost
                                       50

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  TABLE  20.  SUMMARY  OF TOTAL  ESTIMATED  COSTS  FOR  CHARGED  FOG SPRAY  DEVICE*
                                   Cost  per  charged  fog  spray device
Item
Purchased Equipment
Installation
Materials
Total Materials
Installation Labor
Indirect Costs
Construction
Overhead
Engineering
Taxes and Freight
Total Indirects
Direct and Indirect
Excluding Auxiliary
Equipment
15% Contingency
Auxiliary Equipment
GRAND TOTAL
Small
fog
spray
$1,535

97
1,632
318


223
228
130
581

2,531
380
1,453
$4,364
Large fog spray
(with air)
$ 2,454

97
2,551
318


223
357
204
784

3,653
548
7,380
$11,581
Large fog spray
(no air)
$ 4,400

83
4,483
292


204
628
359
1,191

5,966
895
230'
$ 7,091
Mobile
fog spray
$ 2,400

- 0
2,400
75


53
336
192
581

3,056
458
- 0 -
$ 3,514
*See Tables  12-15  and  text for break down of costs and bases used.

of small  spray)  =  $2,400,  quantity discount included.  For the version of the
larger charged  fog spray which uses no atomizing air, an additional  $2,000 is
added to  account for the cost of an integral high pressure water pump needed
for hydraulic atomization.  For a mobile version of the spray (no air source;
D.C. battery powered)  with an intermediate coverage area, a price identical  to
the large spray device was used to allow for additional complexity of con-
struction.
     Since industrial  plant air and water systems usually contain solids that
could rapidly plug the filters, built in sprays, additional cartridge filters
for both  the air and water supply to the sprays have been included.   It is
                                       51

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assumed a  bank  of  four  sprays  is  attached  to each filter.  A prorata share of

the cost of a cartridge filter for  the  water and a combination coalescer/filter

for the air is  charged  to each spray.   Costs for the systems are summarized in

Table 21.


 TABLE 21 .  ESTIMATE  OF PURCHASED EQUIPMENT COSTS FOR CHARGED FOG SPRAY DEVICES*
Item
  Cost per
Spray Device
Basis for Calculations
Small Charged  Fog            $1 ,500
  Device
Large Charged  Fog            $2,400
  Device with  Air
  Atomization
Large Charged  Fog            $4,4
  Device with  Hydraulic
  Atomization
Mobile Charged  Fog           $2,400
  Device
Share of Air
  Coalescer
    Small fog spray         $   19
    Large fog spray         $   38
Share of 40 micron
•  Water Filter
    Small fog spray         $   16
    Large fog spray         $   16
                 Current  sales price less assumed 25%
                 discount for purchase in quantity.
                 Cost  of  small fog spray prorated by
                 coverage assuming 0.2 exponent
                 in  cost-capacity equation.
                 Cost  of  large fog spray having air  '„
                 atomization plus $2,000 for in-
                 tegral high-pressure water pump.**
                 Spray for mounting on front-end
                 loaders, etc.  Assumed to have smaller
                 coverage area than large device, but
                 cost  the same because of more complex
                 construction.
                 Assume four small fog sprays per 100
                 acfm  filter of cost $75; two large
                 fog sprays per 100 acfm filter


                 Assume four fog sprays per 15 gpm
                 filter of cost $66.
*0nly a part of total costs associated with charged fog spray device installa-
 tion.  See Table 20 for  summary of complete costs.
**Reference'50
***Reference 51


     Installation materials include any water or air piping, mounting equipment,
and electrical hardware.   It  is assumed that the high voltage cable will be in-

stalled in 1/2 in. rigid,  galvanized conduit.  Fifty foot of conduit per spray

is assumed.  In addition,  a prorata share of electrical and water tie-ins
                                       52

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are charged to each spray.  Again, a bank of four charged fog sprays is

assumed, and 50 ft of #14 copper wire with accompanying conduit,  plus two

water tight and dust tight mounting boxes and 50 ft of one-half inch carbon

steel water line are included for each bank.   Calculations for installation
materials are shown in Table 22.


TABLE 22.   ESTIMATE OF INSTALLATION MATERIAL  COSTS FORCHARGED FOG SPRAY  'DEVICE'
Item
Cost per Fog
Spray Device
     Basis for Calculations
Conduit for High Voltage
   Cable
Share of Conduit for
   110V Feed-line

Share of Wiring for 110V
  Feed-line

Share of Mounting Boxes
  for 110V Feed-line
Share  of Water Supply
  Line


Share  of Air Supply
  Line
    $ 21



    $  5


    $ 35


    $ T3



     $  9



     $  14
50 ft of 1/2" diameter rigid
diameter rigid galvanized steel
conduit per fog spray at $0.42/ft**

50 ft of conduit as above for a  bank
of four fog sprays.

50 ft of #14 copper wire for a bank
of four fog sprays at $2.80/ft.**

Two pull-boxes, water tight and dust-
tight for a bank of four fog sprays
at $36 each.**

50 ft of 1/2" diameter Schedule  40,
galvanized, steel  pipe for a bank of
four fog sprays at $0.69/ft.**

50 ft of 1" diameter, Schedule 40,
galvanized, steel  pipe for a bank of
four fog soravs at $1.10/ft.**	
*0nly a part of total  costs associated with charged fog spray device installa-
 tion.   See Table 20 for summary of complete costs.

**Reference 52.


                                                                  52
     Installation labor for electrical equipment as cited by Means   is used.

An additional  two hours per fog spray of electrician labor and two hours of

laborer time per fog spray are included for mounting of the fog spray control

box and the fog spray nozzle.  Two hours per fogger of pipefitter time is in-

cluded for water line connections.  Labor costs are tabulated in Table 23.
                                      53

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                       J^^
Item
                        Cost per
                        Charged Fog
                        Spray Device
                                                 Basis for Calculations
Conduit for High           $ 61
  Voltage Cable


Share of Conduit for       $ 15
  110V Feed-line

Share of Wiring for        $106
  110V Feed-line

Share of Mounting          $ 14
  Boxes for 110V
  Feed-line
Share of Water Supply      $ 21
  Line

Share  of  Air  Supply        $  26
  Line
Mounting of Spray          $ 75
   Nozzle and Control
   Box
                                            50  ft  of  1/2" diameter rigid
                                            galvanized steel conduit per fog
                                            spray  at  $1.22/ft.**

                                            50  ft  of  conduit as above  for a
                                            bank of four  fog sprays.

                                            50  ft  of  #14  cooper wire for a bank
                                            of  four fog  sprays at  $8.45/ft.**

                                            Two pull-boxes, watertight and dust-
                                            tight  for a  bank of four fog sprays
                                            at  $27 each.**
                                            50  ft  of  1/2" diameter Schedule  40,
                                            galvanized,  steel  pipe for a bank of
                                            four fog  sprays  at $l.,68/ft.**

                                            50 ft  of 1"  diameter,  Schedule 40,
                                            galvanized,  steel  pipe for a bank
                                            of four fog  sprays at $2.10/ft.**

                                            Per fog spray:   2 hrs. of electrician
                                            at $13.70/hr.;  2 hrs.  of pipefitter at
                                            $14.00/hr.;  and 2 hrs. of laborer  at
                                            $9.70/hr.**
*0nly  part of total  costs  associated
See  Table 20 for summary of complete

**Referenee 52
                                      with  charged fog spray device installation.
                                      costs.
      Some  investment is associated with  auxiliary equipment needed for the fog

sprays.  A prorata share of a plant air  compressor (based on air consumption)

is  charged to each fog spray.   A 10,000  standard cubic feet per minute centri-

fugal  compressor is used for the basis.   Similarly, a share based on water con-

sumption of a 1,000 gpm centrifugal  pump  station, discharging at 100 psig, is

charged to each spray.  Costs  for these  auxiliary pieces of equipment are pre-

sented in  Table 24.   Notice that the share of air compressor costs is a large

share  of the costs for air  atomized systems.
                                          54

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TABLE 24.   ESTIMATE OF AUXILIARY _LQU-LPJiElL_COSTS FOR CHARGED  FOG SPRAY DEVICE _	

                       Cost per
                       Charged Fog
Item	Spray Device	Basis  for Calculations	
Share of Compressor
Costs for Plant  Air System
  Small  fog  spray          $1,430
  Large  fog  spray          $7,150
    (air atomized)

  Large  fog  spray            -0-
    (hydraulically
     atomized)
  Mobile fog spray           -0-


Share of Pump Costs
for Plant Water  System
 Small  fog spray          $ 23
 Large  fog spry            $230
  (both  versions)
 Mobile  fog  spray          -0-
Proration  by air consumption of  the
investment for a 10,000 scfm centri-
fugal  compressor delivering air  at
100 psig.   (Estimated total erected

cost = $1.43 x ID6)   Small fog spray
air consumption of 10 scfm.  Large
fog spray  air consumption of 50  scfm
for air atomized version, no air for
hydraulically atomized version.   No
air consumption for  mobile fog spray.
Proration  by water consumption of
the investment for a 1000 gpm centri-
fugal  pump delivering water at 100
psig.   (estimated total  erected  cost
of $57,400).*  Small fog spray water
consumption of 0.25  gpm.  Large  fog
SDraywater consumption of 2.5 opm**
*Cost escalated  to January 1978, 25% contingency included.   Reference 51.
**'Reference  30.
     Indirect  costs charged to each spray device  are:   (a)  construction overhead

costs of 0.70  x  (labor costs), (b) engineering costs  of 0.14  (direct equipment

costs),  and  (c)  taxes and freight of 0.08 x (direct equipment costs).

Finally  a contingency fee equal to 15 percent of  total  direct and indirect

costs (excluding the auxiliary equipment investment which  had its contingency

added separately)  is added.  The indirect costs are shown  on  Table 20, "Summary

of Total  Estimated Costs for Charged Fog Spray Devices."

     In  addition to the capital investment associated with  operating a charged

fog spray device,  there are utility requirements  as well—electricity, water,

and compressed air.  Table 25 summarizes the utilities  requirements for operation

of a charged fog spray device all converted to an equivalent  kilowatt basis.  By

far the  largest  energy requirements are for the compressed  air used to atomize

and project  the  spray droplets.  The energy required  to charge the droplets  is

minor and is not representative of the total energy consumption of the charged

fog device.
                                      55

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                          Energy  Requirement,
                          Equivalent  Kilowatts
                          per  Charged  Fog
Item
Pumping Energy for Water
Small fog spray
Large fog spray (air
atomized)
Large fog spray
•hydraulic-ally atomized)
Mobile fog spray



Compression Energy for Air
Smal 1 fog spray
Large fog spray
(air atomized)
Large fog spray
(hydraulically
atomized)
Mobile fog spray
Electrical requirements
n
for Charging
— • ^j ' • • j
Small fog spray
Large fog spray
(both versions)
Mobile fog spray
Total Equivalent Kilowatts
Small fog spray
Large fog spray
(air atomized)
Large fog spray
(hydraulically atomized)
Mobile fog sprav
Device

0.02
0.16


1.59
1.59



2.66
13.32

-0-


-0-


0.03
0.30
0.30

2.71
13.78

1.89

1.89
Basis for Calculations
Water from centrifugal pump
at 100 psig discharge pressure,
except hydraulically atomized
version has 600 psig recipro-
cating pump; 0.25 gpm for small
fog spray; 2.5 gpm for large fog
spray; Mobile fog spray assumed
to have same requirements as
hydraulically atomized large fog
spray.
Air from plant air compressor dis-
charging at 100 psig; 10 scfm for
small fog spray; 50 scfm for large
spray; no air required for hydrauli
cally atomized version; assumed no
air required for mobile fog spray.


Charging requirement for small fog
spray from manufacturer; require-
ment for large spray prorated by
water consumption. Mobile spray
requirement assumed equal to large
fog spray.







*Reference 30.
                                         56

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       5.0  WATER SPRAYS WITH ADDITIVES FOR CONTROLLING FUGITIVE EMISSIONS

     It has been suggested that water sprays containing surface active  agents
would be more effective in collecting entrained  dust  than  pure  water sprays.
The equipment for such a spray system would consist of hydraulic or air atomization
spray nozzles, a reservoir and metering pump for injecting the  additive into
the water, and the appropriate connecting piping.   Sprays  with  or without
additives have been successful in reducing dust  emitted from conveyor belts and
are used in quarries and mining operations.
     There are conflicting reports of whether or not  additives  improve  particle
collection by water sprays.   Much of the conflict comes from a  confusion in the
mechanisms working to reduce total particulate levels.  There are two ways in
which water suppresses part.iculate:   (a) by wetting and immobilizing dust
before becoming airborne and (b) by removing already  suspended  airborne particles.
     To suppress dust formation, water is sprayed onto the surface of a solid
material, for example ore concentrate on a conveyor belt.   The  water ideally
spreads into the interstices of the solid, and wets the surface of fine particles
thus making them adhere to the larger lumps of material.   The wetted solid
material then has less tendency to generate dust as it is  handled since the
small, easily entrained particles have been immobilized.   However, since water
has a very high surface tension (roughly 70 dynes/cm), it  often is not  effective
in spreading into the solid material and forming a water film around dust
particles.  Instead it stays on the surface as thick  droplets with resulting
poor dust suppression.  The high surface tension interferes with the wetting,
spreading, and penetrating needed for suppression.                                        |
     To improve the efficiency of suppression, various compounds known  as sur-
factants, or wetting agents, are added to the water.   These compounds are
composed of a hydrophobic, or water-hating, group (usually a long chain hydro-
carbon) and a hydrophilic, or water-loving, group (usually a sulfate, sulfonate,
                                       57

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 hydroxide, or ethylene oxide).  When mixed with water, surfactants concentrate
at the air-water interface with  the  hydrophilic end aligning in the water layer
and the hydrophobia portion of the molecule extending into the air layer.  By
preferentially aligning at the water-air interface, the surfactants can reduce
the surface tension to around 30 dynes/cm and improve the wetting and penetra-
tion of the water.  The levels of surfactant needed to effect such a surface
tension reduction is very low--0.03  to 0.1 percent.  Additives other than
surfactants may be used in some  cases to form a "crust" on storage piles, etc.,
and reduce windblown resuspension of dust.
                                          »
     Water sprays are also sometimes used to try and remove particles which
have already become airborne.  The droplets from a water spray collect and
coalesce the fine entrained particles and increase-their settling rate.  It has
been suggested that surfactants  would improve particle removal for this case
also by allowing the dust particle to penetrate the water droplet more easily,
however, there is little evidence that this, occurs.  Most investigators report
surfactants do little to supress airborne respirable dust.    Walton and
        ro
Woolcock   exposed equal size droplets to the same dust concentration; one
droplet with a wetting agent and the other without.  They found no significant
difference in collection efficiency  for the two drops.  In a recent study,
               59
Woffinden et al   have reported  only small effects of collection efficiency, if
any, can be attributed to surface tension changes.  Indeed, the effect of
adding surfactant may be slightly unfavorable.
     In summaryj water sprays with additives can be used to reduce suspension
of hard-to-wet solids, but have  an advantage over conventional water sprays
only for reducing dust generation from dusts which have not already been suspended.
Additives do not substantially improve the collection of particles which have
already become airborne. Thus, they  are not substitutes for charged fog spray
applications.  The addition of surfactants or other additives should be con-
sidered for such applications as conveying and storage bins where the product
is not water sensitive and can be kept moist to reduce dust entrainment from
the solid.
                                         58

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           6.0  BUILDING EVACUATION FOR CONTROLLING FUGITIVE EMISSIONS

     This section discusses the costs, energy consumption, and known applications
of building evacuation as a means of controlling fugitive particulate emissions.
The results of this section are used as a basis of comparison for the charged
fog spray devices.
DESCRIPTION OF BUILDING EVACUATION
          One method of eliminating fugitive particulate emissions.from smelting
operations which are inside a building is to install  ductwork on the building
roof and large fans which draw the particulate-laden  gases from the building
and pass them through a collection device.  Typically,  a baghouse is the control
device selected for building evacuation.  Any fugitive  particulates escaping
inside the smelter building are collected by the evacuation system and overall
control efficiency for fugitive emissions is quite high for building evacuation--
from 90 to over 95 percent.
     While attractive from an environmental-control  viewpoint, building evacua-
tion has several serious drawbacks.  By enclosing the building, the emissions
can only escape through the roof ducts and high levels  of particulate, S02,
etc., may build up inside the building in the workplace requiring breathing
equipment and causing occupational health concerns.   An evacuation system may
collect enough gas to sufficiently ventillate the workplace overall and yet
still have unacceptable local pollutant concentrations  because of "dead spots"
in the air flow pattern.  Figure 10 illustrates this  effect.  In smelting
operations, such dead spots may create excessive temperatures as well as high
pollutant levels in some local areas.
     A second drawback to building evacuation systems is the large airflow
required and the attendant high energy consumption by the blower.  As a general
rule for controlling emissions with hoods, the closer the hood to the source,
the less evacuation air is required.  For the particular case of building
evacuation, the intakes are located far from the particulate sources and large
volumes of air.with low particulate loadings are collected.

                                       59

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Dead Spot
               Figure 10. Schematic of "Dead Spots" in Building Evacuation System.
                                                60

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     Building evacuation systems have been successfully  applied to electric arc
                                                  C]  CO
furnace melt shops in the iron and steel  industry.   '     One  converter building
in the copper industry has been fitted with a building evacuation system
while there are no known large building evacuation  systems  in the lead smelting
industry.  The evacuation system in the copper smelting  plant has caused severe
heat and SO^ levels in the upper areas of the building but  this may be due  to
inadequate fan volumes and the difficulty in designing for  good air flow patterns
in a retrofitted application.
COST AND UTILITY CONSUMPTION FOR BUILDING EVACUATION
     During some test work on an electric arc furnace building evacuation
system, it was reported that a total  of 1230 kW load was being drawn by the
main baghouse fans treating 499,000 acfm of air at  95°F.    The reverse air fan
for this system was rated at 150HP which corresponds  to  roughly an additional
125 kW load for a total of 0.00272 kW/acfm.  The baghouse had an air-to-cloth
ratio of 2.3:1.  No investment costs  were given.
     The retrofitted building evacuation system at  the smelter cost approxi-
mately $8.5 million for a gas volume  of about 600,000 acfm.10  Three 700HP  fans
are used for this system for a utilities consumption  of  about 0.0029 kW/acfm.
As was noted, the air is not changed  frequently enough in this installation
(2.7 minutes per air change) to prevent excessive local  concentrations of
           CO                                                                   CO
pollutants.    An estimate was made by the Arizona  Department of Health Services
                                                                cc
for a "typical" smelter, as defined by the U.S.  Bureau of Mines,   for installing
building evacuation on a 100,000 ton  per year smelter for the case of 1.5 air
changes per minute.  The air flow for this estimate was  2,200 kacfm.    Cost
for this estimate are presented in Table 26.
     For comparing building evacuation with charged fog  spray devices, an
initial investment of $6,808,000, (3.09 $/acfm)  and utility consumption of  6000
kW were used for a building evacuation system for a converter building on a
copper smelter.  The costs and utilities  for building evacuation in a lead
smelter are similar to those for a copper smelter.  However,  it is felt that a
larger volume of building space must  be evacuated in  a lead smelter.  The
evacuated building volume was assumed to  be 150 percent  of  the building volume
for copper smelting.  Utility requirements were prorated directly by 1.5 to vie
9,000 kW, while capital costs were prorated using the 0.6 power rule to give
1.5°'6 x $6,808,000 = $8,683.000.
                                          61

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         TABLE 26.  CAPITAL AND OPERATING COST FOR BUILDING  VENTILATION
                    SYSTEM AT TYPICAL COPPER SMELTER*
                                                            June  1978 Prices
Direct Plant Costs:
     Baghouse
     Fans and Motors
     Electrical
     Ductwork and Piping
     Alterations to Building
     Equipment Supports

Indirect Costs:
     Engineering (14% T.D.C.)
     Field Expense (20% T.D.C.)
     Contractors Fee (2.5% T.D.C.)

     Start-up (3.5% T.D.C.)
     Contingency (20% T.I.)
TOTAL DIRECT COST
TOTAL INVESTMENT
                                   TOTAL CAPITAL
$2,870,000
   741 ,500
   178,500
   179,000
    40,000
    60,000
$4,069,000

$   70,000
   814,000
   102,000
$5,555,000
   142,000
 1,111 ,000
$6,808,000
Estimated Annual Operating Cost
*Table from Reference 63.
                                       62

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         7.0  COMPARISON OF CHARGED FOG SPRAYS WITH BUILDING EVACUATION

     Estimates of the rough quantities of the small, large,  and mobile charged
fog sprays needed to control fugitive emissions in  smelters  are shown in  Tables
27 and 28.  The corresponding points of application are shown in Figures  11  and
12.  These quantities are then used to estimate the cost and energy consumption
of charged fog sprays applied throughout copper and lead smelters.
     For application of charged fog sprays to a lead smelter, estimated capital
investment is (24 large sprays x $7,091 each) + (4  mobile sprays x  $3,514 each)  +
(29 small sprays x $4,364 each) for a total  of $311,000.  The utility con-
sumption for the charged fog sprays in a lead smelter would  be (24  large  sprays
x 13.78 kW each) + (4 mobile sprays x 1.89_each) +  (29 small sprays x 2.71 kW
each) for a total of 417 kW.  For building evacuation, the estimated capital
costs are $8,683,000 and the utility consumption is 9000 kW.
     Capital investment (including installation and all  auxiliary equipment)
for application of charged fog sprays to a copper smelter is (24 large sprays x
$7,091 each) + (6 mobile sprays x $3,514 each) + (40 small sprays x $4,364
each) for a total of $366,000.  The utility consumption for  the charged fog
sprays in a copper smelter would be (24 large sprays x 13.78 kW each) + (6
mobile sprays x 1.89 kW each) + (40 small sprays x  2.71  kW each) for a total
of 450 kW.  For building evacuation, the corresponding costs are $6,808,000
and the utilities usage is 6,000 kW.
     While both capital  investment and energy consumption are higher for  build-
ing evacauation, the reduction of total particulate and  elemental lead emissions
are also greater for building evacuation because of the  higher collection
efficiency and the larger number of sources  covered by a building evacuation
system.
     Table 29 shows what are, by all  accounts, rough estimates of the emission
reductions expected from the application of  charged fog  sprays and  the appli-
cation of building evacuation.  Estimated reductions are shown for  both total
particulate fugitive emissions and elemental  lead fugitive emissions.
                                        63

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    TABLE 27.  POTENTIAL APPLICATIONS OF CHARGED FOG SPRAYS  IN  LEAD  SMELTING'
Application
       Number
Large  Mobile  Small
                    Comments
A-Railcar unloading

B-Conveyor transfer
C-Conveyor transfer
D-Conveyor transfer
E-Mix tripper conveyor

F-Conveyor transfer
G-Conveyor transfer
H-Conveyor transfer
I-Crusher discharge
J-Pelletizing drum
K-Conveyor transfer
L-Conveyor transfer

M-Roll grizzly discharge

N-Conveyor transfer"
0-Conveyor transfer
P-Blast furnace tripper
  conveyor
Q-Front-end loader
          TOTAL
 16
  2

  2
  2


 24
JL
 4
                 3
                 3
                 3
                 2
                 2
                 2
                 4-
                 4
                 2
                 2
                 2
29
              Installed as "curtain."
              8 on each end of shed.
                      Mounted to move with
                      tripper.
             Large sprays used to
             cool sinter
             Large spray used to cool
             sinter
             Mounted to move with
             tripper.
 Refer to Figure 11 for locations of applications.
""Small charged spary coverage = 2 ft x 6 ft; Mobile charged  spray  coverage =
 3 ft x 10 ft; large charged spray coverage = 6 ft x 20 ft.
                                        64

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 '  TABLE 28.  POTENTIAL APPLICATIONS OF CHARGED  FOG  SPRAYS IN  COPPERJiMELTlNG_c

                                       Number
Application                     Large  Mobile  Small           Comments
A-Railcar unloading

B-Conveyor transfer
C-Conveyor transfer
D-Conveyor points in transfer
  house
E-Ore bin tripper conveyor
16
Installed as "curtain."
8 on each end of shed.
                3
                3
                      Mounted to move with
                      tripper.
F-Conveyor transfer
G-Conveyor transfer
H-Fine ore bin tripper con-
veyor 2
I -Drier discharge conveyor
J-Conveyor transfer
K-Concentrate stacker 2
L-Dozer and front-end loader

M-Conveyor transfer
N-Conveyor transfer
0-Tripper conveyor 2
P-Conveyor transfer
Q-Conveyor transfer
R-Conveyor transfer
TOTAL 24
2
4
Mounted to move with
tripper.
2
2

6 Medium-size} mobile units
mounted on dozer/loader
4
4

2
4
_ _i
6 40
 Refer to Figure 12 for locations of applications.

 Small charged spray coverage = 2 ft x 6 ft;  Mobile charged spray coverage =
 3 ft x 10 ft; Large charged spray coverage = 6 ft  x 20 ft.
                                        65

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                                                    - NETUHN BLAH
CTl
CTl
                                                                      	a-'     -\.	i
                                                                      „„   .    ruu* p-""f f. J "-»" »0 ««"« '»"»
                                                Figure 11.  Charged Fog Spray Application Points in Lead Smelting.

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            1 RAILCAR OUMfMNG
                                                                                                   TRIPPER CONVEYOR
CONVCHTIR SL*Q
TO COOLING P1T1
                Figure 12. Charged Fog Spray Application Points in Copper Smelting.
                                                            67

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     TABLE 29.  COMPARISON OF CHARGED FOG SPRAYS WITH BUILDING EVACUATION
Item                                  Lead Smelting        Copper  Smelting

Reduction in  fugitive total particu-
late emissions
  by application of  charged sprays         30%                  20%
  by application of  building evacuation    45%                  40%
Reduction in  fugitive elemental lead
 emissions
  by application of  charged sprays         40%                  35%
  by application of  building evacuation    75%                  65%
Estimated capital  investment
  for application  of charged sprays        311 k$               366  k$
  for application  of building evacuation 8,683 k$_             6,808  k$
Electrical requirement
  for application  of charged sprays        417 kW               450  kW
  for application  of building evacuation 9,000 kW             6,000  kW
     Several assumptions were made in compiling Table 29.   The overall  collection
efficiency of the charged fog sprays was taken to be 60 weight percent; for
building evacuation, 95 weight percent was used.   The charged fog  sprays  were
considered inapplicable for hot, turbulent areas  such as molten metal  transfer,
lead sintering, and copper converter leakage.  Building evacuation was  not
considered to be effective for reducing emissions from loading onto or  out of
storage piles.  From the fugitive emission estimates, presented in Tables 2
and 3, the reduction of total particulate and elemental lead emissions  were
made source-by-source.  Some of the emission source grouplings in  Tables  2
and 3 included emissions from both inside and outside the process  buildings--
for example, handling  and transfer of lead ore concentrate.   In such cases,  it
was arbitrarily assumed that one-half of the emissions occurred in the  building
and would be collected by the building evacuation system at 95 percent  efficiency.
It was also assumed that an evacuation system could be put on the  rail car un-
loading sheds but that it would not be as efficient as the system  on the  main
buildings because of incomplete enclosure.  A fifty percent overall  capture
and collection efficiency was used for railcar unloading emissions controlled
by an evacuation system.
                                       68

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     Superficially,  the  figures  in  Table  29 indicate charged  fog  sprays  to  be
a more cost effective  means  for  pollution control than  building evacuation--
10 to 20 k$ required for each  percentage  reduction  in emissions by  sprays
versus 100 to 200 k$ required  for each  percent reduction by   building
evacuation.  Similarly the electrical requirement is much  lower for the
charged fog sprays—15 to 30 kW  for each  percentage reduction versus 150 to
200 kW for the building  evacuation  system.
     However, in spite of the  apparent  attractiveness of charged  fog sprays,
the authors feel that  there  are  several practical problems which  prevent them
from supplanting building evacuation  or secondary hooding  as  fugitive  control
techniques.  The first and main  objection is  their  limited applicability.   Water
sprays are only suitable when  the process can  tolerate  water, when,  the emissions
are "from localized sources,  when there  is not  a  great deal of air turbulence
and when the air is  not  at high  temperatures.  These limitations  rules them
out for such major sources of  fugitive  emissions as converter leakage,
sintering, and metal tapping,  pouring,  and casting.  A  second major limit
on charged fog spray control is  the collection of the agglomerated  particles.
Throughout this treatment, it  has been  assumed that once suspended  particles
collide with a water droplet,  they  are  permanently  removed from the atmosphere.
This is a valid assumption for such applications as conveyor  transfer  points
in moderately still  air  where  the agglomerated dust settles out and is returned
to the process.  However, when particles  from, say, a railcar unloading  station
are contacted with spray droplets,  they may settle  out  on  the ground,  dry  out,
and be reentrained.
     One control option  not  yet  considered in  this  report  is  localized hooding
at fugitive emission sources.  Figure 13  shows two  options for controlling
emissions from a railcar unloading  station—a curtain of charged  fog sprays and
a push-pull collection system.  This  application gives  a direct  comparison of
charged fog sprays with  another  control technique on the same source.   Using
recommended push-pull  design procedures   and assuming  the same  utility  re-
quirements and cost per  cubic  foot  as was used for  building  evacuation  the
following estimates were made:  (a) 5.8 kW and $6,500 per  lineal  foot of opening
for a push-pull system and (b) 2.3  kW and $1,900 per  lineal  foot for the
                                      69

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                View from above shed opening
                        I	1
Pressure
  Slot
                        i        r
                         Air Flow
                       J	I
             Application of push-pull local hooBjng
.Suction hood
                     Air and participates
                     to fan suction and
                     baghouse
                                                       Air, water, and
                                                      electrical supply
                                                                   A
                      Bank of charged fog sprays
          Application of Charged Fog Spray Curtain.
Figure 13.  Push-pull Local Hooding Versus Charged Fog Spray Curtain.
                                       70

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charged water spray curtain.  Neglecting the potentially serious  problem of
particle reentrainment after spray evaporation, the charged sprays  could in
theory collect about half of the fugitive dust less expensively and with less
energy than local hooding.  However, it is pointed out that the sprays  can
only collect about half the particulate and if greater than fifty percent
efficiency is needed, some other control method must be used in spite of any
extra expense.
     This report has treated building evacuation and charged fog  sprays as
either/or control techniques.  It makes more sense to consider them as  com-
plementary control devices instead of mutually exclusive techniques.  For
high temperature, large scale, turblent emissions, either building  evacuation
or secondary hooding is require'd to collect the fugitive emissions;  Charged
fog sprays are better suited for smaller, localized emission sources.  Two
applications for which charged sprays may be particularly advantageous  over
other controls are:  (a) mobile sources such as front-end loaders where any
other type of control is impossible and (b) areas such as sanders or grinding
wheels where personnel exposure must be reduced without impeding  access.
     A final caveat concerning the evaluation of charged fog sprays made in
this report:  only a screening evaluation has been made.  To confirm their
predicted performance in an industrial environment—where cross-drafts, reen-
trainment, and upsets occur—requires field tests and the measurement of actual
reductions obtained with and without the device in operation.
                                       71

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                              8.0  REFERENCES

1.   PEDCo - Environmental, Cincinatti, OH for U.S. EPA Contract No.
    6802-2535.  Task 1  for Metals and Inorganic Chemicals Branch, IERL-
    Cinn. Work in progress.

2.   The Research Corporation of New England, Technical Manual for Measure-
    ment of Fugitive Emissions: volumes 1 through 3, U.S. Environmental
    Protection Agency Rep. Nos. EPA-600/2-76-089a (April 1976); EPA-600/
    2-76-089b (May 1976); and EPA-600/2-76-089c (May 1976).

3.   PEDCo Environmental, Technical Guidance for Control of Industrial
    Process.  Fugitive Particulate. Emissions, U.S. Environmental Protection
    Agency, Research Triangle Park, N.C., Rep. No-. EPA-450/3-77-010
    (March 1977).

4.   Environmental Protection Agency, Background Information for New Source
    Performance Standards: Primary Copper, Zinc, and Lead Smelters, vol.1  -
    Proposed Standards, U.S. EnvironmentaJ Protection Agency, Research
    Triangle Park, N.C'., Rep. No. EPA-450/2-74-002a (October 1974).

5.   Gibson, F.W., "New Brick Lead Smelter Incorporates Forty Years of
    Technical Advances," Engineering and Mining Journal, pp. 62-67,
    (July 1968).

6.   Constant, P., M. Marcus, and W. Maxwell, Sample Fugitive Lead Emissions
    from Two Primary Lead Smelters, U.S. Environmental Protection Agency,
    Research Triangle Park, N.C., Rep. No. EPA-450/3-77-031 (October 1977).
7.   "Herculaneum:  Tops in U.S. Refined Lead Output," Engineering and Mining
    Journal , pp. 87-91, (November 1976).

8.   Katari, V., G. Isaacs, and T.W. Devitt, Trace Pollutant Emissions from the
    Processing of Metallic Ores, U.S. Environmental Protection Agency, Washing-
    ton, D.C., Rep.  No. EPA-650/2-74-1151 (October 1974).

9.   Daugherty, D.P.  and D.W. Coy, "Trip Report-5/11/78 Visit to St. Joe Lead
    Company, Herculaneum Lead Smelter, Herculaneum, Missouri, Research Triangle
    Institute, Research Triangle Park, N.C.

10.  Environmental Protection Agency, Evaluation of Zinc  Fuming Furnace Emissions,
    Bunker Hill Lead Smelter, Kellogg, Idaho, U.S. Environmental Protection
    Agency, Office of Enforcement, National Enforcement  Investigations Center,
    Denver, CO., Rep. No. EPA-330/2-77-010  (April 1977).
11.  Charles River Associates,  Inc., Economic  Impact of the  Proposed EPA National
    Ambient Air Quality Standard for Lead:  Background Support Document,  Charles
    River Associates, Inc., Cambridge, Mass.  CRA  Report  #398, pp. 37-45,
    (March 1978).
                                        72

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12.  Bohn, R., T. Cuscino, Jr., and C. Cowherd, Jr., Fugitive Emissions  from
     Integrated Iron and Steel Plants, U.S. Environmental  Protection  Agency,
     Washington, D.C., Rep. No. EPA-600/2-78-050.

13.  Shearer, D.L. and E.J. Brookman, Impact Analysis of EPA Proposed National
     Ambient Air Quality Standard for Lgad on Primary and  SecondaryJ.ead_
     Smej ters, The Research Corporation of New England, Wethersfield, Conn.
     (February 1978).

14.  Jones, H.R., Pollution Control in the Nonferrous^ Metals Industry:  1972,
     Noyes Data Corporation, Park Ridge, N.J., p. 145, (1972).

15.  Dorn, C.R., J.O. Pierce, G.R. Chase, and P.E. Phillips, "Environmental
     Contamination by Lead, Cadmium, Zinc, and Copper in a New  Lead-Producing
     Area," Environmental Research 11, No. 2, pp. 159-172, (April  1975).

16.  Research Triangle Institute, Air Pollution from Lead  and Zinc Processing
     Plants:   Trepca, Yugoslavia, Research Triangle Institute,  Research
     Triangle Park, N.C., Contract No. 68-02-1325, Task 47, p.  14.

17,  Harris,  D:B., and D.C. Drehmel, "Fractional  Efficiency of  Metal  Fume
     Control  as Determined by Brink Impactor," presented at 66th Annual
     Meeting  of the Air Pollution Control Association, Chicago, Illinois.
     June 24-28, (1973).

18.  Dorn, D.R., J.O. Pierce, II, P.E. Phillips,  and G.R.  Chase, "Airborne  Pb,
     cd, Zn and Cu Concentration by Particle Size Near a Pb Smelter."  Atmospheric
     Environment, v. 10, pp. 443-445 (1976).

19,  Environmental Protection Agency,  Background Information for New Source
     Performance Standards, U.S. Environmental Protection  Agency, Research
     Triangle Park, N.C., Rep. No. EPA-450/2-74-002a, (October  1974).

20.  Weisenberg, I.J. and J.C. Serne, Design and Operating Parameters for
     Emission ControlStudies, Volumes a through k, U.S. Environmental  Pro-
     tection  Agency, Washington, D.C., Rep.. Nos.  EPA-600/2-76-036a through  k,
     (February 1976).

21.  Daugherty, D.P., and D.W. Coy, "Trip Report - 7/28/78, Visit to  Kennecott
     Copper Corporation, Hayden Smelter, Hayden, Arizona," Research Triangle
     Institute, Research Triangle Park, N.C. (1978).

22.  "Fugitive Arsenic Emissions From Copper Smelters," Contracted by Office of
     Air Quality Planning and Standards, Emissions Standards and Engineering
     Division, U.S. Environmental Protection Agency, Durham, N.C., (work in
     progress).

23.  "Components of Concentrates Processed in the U.S. "Summary of confidential
     information in Research Triangle Institute files.
                                           73

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24.   Wagner,  W.L.,  "Environmental Conditions in U.S. Copper Smelters," HEW,
     NIOSH, Division  of Technical Services, Salt Lake City, Utah, HE20.7102:C
     79,  HEW  Publication  No. NIOSH 75-158  (April 1975).

25.   Research Triangle Institute, "Air Pollution Caused by Copper Metallurgy
     in  Bor:   Summary Report," Research Triangle Institute, Research  Triangle
     Park,  N.C.,  EPA  Contract No. 68-02-1325, Task 47 (November  1976).

26.   Thompson, G.S.,  Jr.  and G.B. Nichols:  "Experience with  Electrostatic
     Precipitators  as Applied to the Primary Copper Smelting  Reverberatory
     Furnace" in  Proceedings:  Particulate Collections Problems  Using ESP's
     in  the Metallurgical  Industry.EPA-600/2-77-208 (NTIS PB 274 017/AS),
     U.S.  Environmental Protection Agency, Research Triangle  Park, N.C.
     pp.  234-251  (1977).

27.   Wood,  C.W. and T.H.  Nash III, "Copper Smelter Effluent Effects on Sonoran
     Desert Vegetation,"  Ecology, v  57, pp. 1311-1316 (1976).

28.   Hoenig,  Stuart A., Use of Electrostatically Charged  Fog  for Control  of
     Fugitive Dust  Emissions, U.S. Environmental Protection Agency Rep.  No.
     EPA-600/7-77-131,  (November 1977).

29.   Hassler, H.E., "A New Method for Dust Separation Using Autogenous Elec-
     trically Charged Fog," Journal  of Powder and Bulk Solids Technology, v.2,
     n.l,  pp. 10-14 (Spring 1978).

30.   Communications with  E.W. Drum,  Manager of  the Air Pollution Control
     Department of  Ransburg Electrostatic  Equipment, Indianapolis, IN (May 1978).

31.   Shafrir, U.  and  T. Gal-Chen, "A Numerical  Study of Collision Efficiencies
     and Coalescence  Parameters for  Droplet Pairs and Radii up to 300 Microns,"
     Journal  of the Atomospheric Sciences, v.28, pp. 741-751,  (July  1971).

32.   Slinn, W.G.N., and J.M. Hales,  "A Reevaluation of the Role  of Thermo-
     phoresis as  a  Mechanism of  In-and Below-Cloud Scavenging  "Journal  of the
     Atomospheric Sciences, v.28, pp. 1465-1471  (November 1971).

33.   Lai,  Kuo-Yann, N.  Dayan, and M. Kerker, "Scavenging  of Aerosol  Particles
     by  a Falling Water Drop," Journal of  the Atmospheric Science^,  v. 35,
     pp.  674-682, (April  1978).

34.   Wang,  P.K, and H.R.  Pruppacher, "An Experimental Determination  of the
     Efficiency with  Which Aerosol Particles are Collected by Water  Drops
     in  Subsaturated  Air," Journal of the  Atmospheric Sciences,  v. 34, pp.
     1664-1669, (October  19777";
35.   Grover,  S.N.,  H.R. Pruppacher,  and A.E. Hamielec,  "A Numerical  Determination
     of  the Efficiency with Which Spherical Aerosol Particles Collide with
     Spherical Water  Drops Due to Inertia!  Impaction and  Phoretic  and Electrical
     Forces," Journal of  the Atmospheric Sciences,  v. 34, pp. 1655-1663,
     (October T977T:~~
                                         74

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36.  Ranz, W.E.,  "On  the  Evaporation of a Drop of Volatile Liquid in High-
     Temperature  Surroundings," Transaction of the ASME, pp.  909-913, (1956).

37.  Ranzs W.E. and W.R.  Marshall, Jr., "Evaporation from Drops," Chemical
     Engineering  Progress, v. 48, pp. 141-173, (1952).

38.  Marshall, W.R.,  Jr.,  "Evaporation from Drops and Sprays," Atomization  and
     Spray Drying, Chemical  Engineering Monograph Series No.  J?3 v. 50 (1954).

39.  Masters, K.  Spray  Drying, 2 ed. John Wiley and Sons, New York, (1956).

40.  Melcher, J.R. and  K.S.  Sachar,  "Charged Droplet Technology for Removal  of
     Particulates from  Industrial Gases," Rep. No. APTD-0868, PB-205 187
     (August 1971),

41.  Melcher, J.R. and  K.S.  Sachar,  "Charged Droplet Scrubbing of Submicron  Parti -
     culate," U.S. Environmental Protection Agency, Washington, D.C., Rep.  No.
     EPA-650/2-74-075,  PB-241 262, (August 1974).

42.  Doyle, A., D.R.  Moffett, and B. Vonnegut, "Behavior of Evaporating Electri-
     cally Charged Droplets," Journal of Colloid Science, v.  19, pp. 136-143,
     (1965).

43.  Koscianawski, J.R.,  L.  Koscianowski, and E. Szezepankiewicz, "Effects  of
     Filtration Parameters on Dust-cleaning- Fabrics," Report prepared for U.S.
     Environmental Protection Agency, Contract No. P-5-533-3, EPA Project Officer:
     James H. Turner, Industrial Environmental Research Laboratory, Research
     Triangle Park, N.C.  (December 1976).

44.  Walkenhorst, W., "Deliberations and Studies on the Filtration of Dust-laden
     Gases With Special Allowance for Electric Forces," Staub-Reinhajt Luft,
     v. 29, no. 12 (December 1969).                                       "~

45.  George, H.F., and  G.W.  Poehlein, "Capture of Aerosol Particles by Spherical
     Collectors—Electrostatic, Inertia!, Interception, and Viscous Effects,"
     Environmental Science and Technology, v. 8, n.l, pp. 46-49 (January 1974).

46.  Cheng, L., "Collection  of Airborne Dust by Water Sprays," Industrial Engi-
     neering/Chemistry. Process Design and Development, v. 12, n.3, pp. 221-
     225,  (1973).

47.  Walton, W.H. and A.  Woolcock,"  The Suppression of Airborne Dust by Water
     Sprays," International  Journal  of Air Pollution, v. 3, pp. 129-153, (1960).

48.  Courtney, W.G.,  and  L.  Cheng, "Control of Respirable Dust by Improved Water
     Sprays," Respirable  Dust Control, Proceedings:  Bureau of Mines Technology
     Transfer Seminars, U.S. Bureau  of Mines Information Circular No. IC/8753,
     U.S.  Department  of the  Interior, Washington, pp. 92-108, (1977).

49.  Personal Communication, Bete Fog Nozzle, Inc., Greenfield, MA. (1978).

50.  Personal Communication  with Ken Winter; Facet Enterprises, Inc.; Industrial
     Filter Products  Marketing; P.O. Box 50096, Tulsa, OK 74150, (1978).

51.  Guthrie, Kenneth M.,  Process Plant Estimating, Evaluation, and Control.,
     Craftsman Book Company  of America, Sol ana Beach, Calif.  (1974).
                                          75

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52.   Godfrey, Robert S.s editor-in-chief, Building Construction Cost Data  1978,
     36th annual edition, Robert Snow Means~Co¥panyY Dusbury, Mass.  (1977).
53.   Johnson March Corporation, Dust Control  News, Vol.  No.  1, Philadelphia
     (Fall  1978).
54.   Emmerling, J.E., and R.J. Seibel, "Dust Suppression With Water  Sprays
     During Continuous Coal  Mining Operations," U.S.  Bureau  of Mines Report
     of Investigation 8064,  Washington (1975).
55.   Courtney, W.G., N.I. Jayaraman, and P. Behum, "Effect of Water  Sprays for
     Respirable Dust Suppression With a Research Continuous-Mining Machine,"
     U.S. Bureau of Mines Report of Investigation 8283,  Washington (1978).
56.   Dean,  K.C., R. Havens,  and M.W. Glantz,  "Methods and Costs for  Stabilizing
     Fine-Mineral Wastes."  U.S. Department of  the Interior, Bureau  of Mines,
     R.I. 7894, (1974).
57.   Kobrick, T., "Water as  a Control Method, State of the Art, Sprays and Wetting
     Agents," Paper in Proceedings of the Symposium' on Respirable Coal Mine Dust,
     Washington, D.C., November 3-4, 1969, comp. by R.M. Gooding.Bureau  of
     Mines  1C 8458, pp. 123-133, (1970).
58.   Walton, W.H., and A. Woolcock, "The Suppression  of  Airborne Dust by Water
     Spray," International Journal of Air Pollution,  v.  3, pp. 129-153 (1960).
59.   Woffinden, G.J., G.R. Markowski, and D.S.  Ensor, Effects of Interfacial
     Properties on Collection of Fine Particles by Wet S_crubbers, U.S. Environ-
     mental Protection Agency, Washington, Rep. No. EPA-600/7-78-097 (June 1978).

60.   Emory, S.F., and J.C. Berg, "Surface Tension Effects on Particle Collection
     Efficiency," Appendix to Reference 59.
61.   Kaercher, L.T. and J.D. Sensenbaugh, "Air  Pollution Control  for an Electric
     Furnace Melt Shop," Iron and Steel Engineer^ pp. 47-51, (May 1974).
62.   Research Triangle Insitute, "Trip Report:  Crucible, Inc, Midland, PA",
     (August 4, 1977).
63.   Billings, C.H., "Second Annual Report on Arizona Copper Smelter Air Pollution
     Control Technology," Arizona Department  of Health Services, Phoenix,  AZ
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64.   Roy f. Weston, Inc., "Source Testing Report:  The Babcock and Wilcox  Company
     Electric Arc Furnace, Beaver Falls, PA," EPA Contract No. 68-02-0240, Task
     No. 2, FTS No. 73-ELC-l (January 1973).
65.   Hayashi, M., H. Dolezal, and J.H. Bilbrey, Jr. Cost of  Producing Copper
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67.   American Conference of  Governmental Industrial Hygienists, Industrial
     Ventilation, 9th ed., Edward Brothers, Inc., Ann Arbor, MI, (1966).
                                         76

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                                 TECHNICAL REPORT DATA
                          (Please read Innmctions on the reverse before complsting)
 1. REPORT NO.
  EPA-SOO/7-79-045
                            2.
                                                      3. RECIPIENT'S ACCESSION NO.
 4. TITLE AND SUBTITLE
 Assessment of the  Use of Fugitive Emission
    Control Devices
                                                      5. REPORT DATE
                                                       February 1979
                                                      6. PERFORMING ORGANIZATION CODE
 1. AUTHOR(S)

 D.P.  Daugherty and D.W. Coy
                                                      8. PERFORMING ORGANIZATION REPORT NO
 9. PERFORMING ORGANIZATION NAME AND ADDRESS
 Research Triangle Institute
 P.O.  Box 12194
 Research Triangle Park, North Carolina 27709
                                                      10. PROGRAM ELEMENT NO.
                                                      EHE624
                                                      11. CONTRACT/GRANT NO.

                                                      68-02-2612. Task 48
 12. SPONSORING AGENCY NAME AND ADDRESS
 EPA, Office of  Research and Development
 Industrial Environmental Research Laboratory
 Research Triangle Park, NC  27711
                                                      13. TYPE OF REPORT AND PERIOD COVERED
                                                      Task Final: 2-12/78	
                                                      14. SPONSORING AGENCY CODE
                                                       EPA/600/13
 15.SUPPLEMENTARY NOTES IERL_RTP project officer is Dennis C. Drehmel, MD-61,  919/541-
 2925.
is. ABSTRACT
               repOrt compares the efficiencies and utility consumptions expected
 from three fugitive emission control techniques — building evacuation, charged fog
 sprays , and water sprays with additives — if they were applied in primary lead and
 copper smelters.  Estimates are provided of the reduction of total suspended parti-
 culate emissions and the reduction of elemental lead emissions from smelters when
 fugitive control is applied.  Charged fog water sprays are emphasized: they enhance
 particulate collection by putting an electrostatic charge on fine water droplets. Buil-
 ding enclosure and evacuation is used as a basis with which such water sprays are
 compared. Available cost and energy consumption data were used to assess the
 competitiveness of charged fog sprays. Charged fog sprays were found to be less
 efficient  than building evacuation, but also less expensive and less energy intensive
 by about a factor of 10.  Charged fog sprays  cannot replace conventional smelter tech-
 niques (e.g. ,  secondary hooding or building evacuation) because they are not suitable
 for the typical large-volume, high-temperature,  turbulent air streams.  They are
 better suited for smaller scale, localized emission sources (e. g. , conveyor trans-
 fer points) which contribute only a fraction of  the fugitive particulate emissions.
17.
                              KEY WORDS AND DOCUMENT ANALYSIS
                 DESCRIPTORS
                                           b.IDENTIFIERS/OPEN ENDED TERMS
                                                                  c. COSATI Field/Group
 Pollution
 Dust
 Aerosols
 Leakage
 Processing
 Evacuating
                      Fogging
                      Spraying
                      Additives
                      Lead
                      Copper
                      Smelters
                      Electrostatics
Pollution Control
Stationary Sources
Fugitive Emissions
Particulate
Charged Fog Sprays
Water Sprays
13B
11G
07D

13H
07A

07B

11F
20C
13. DISTRIBUTION STATEMENT
 Unlimited
                                           19. SECURITY CLASS (This Report)
                                           Unclassified
                                                                  21. NO. OF PAGES
                                                                       85
                                          20. SECURITY CLASS (Thispage)
                                          Unclassified
                                                                  22. PRICE
EPA Form 2220-1 (9-73)
                                            77

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