Lnited States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory '
Cincinnati OH 45268
EPA-600/2-78-004L
May 1978
Research and Development
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have 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 ENVIRONMENTAL PROTECTION TECH-
NOLOGY series. This series describes research performed to develop and dem-
onstrate instrumentation, equipment, and methodology to rep.air or prevent en-
vironmental degradation from point and non-point sources of pollution. This work
provides the new or improved technology required for the control and treatment
of pollution sources to meet environmental quality standards.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/2-78-004L
May 1978
SOURCE ASSESSMENT: CRUSHED STONE
by
T. R. Blackwood, P. K. Chalekode, and R. A. Wachter
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
Contract No. 68-02-1874
Program Element No. 1BB610
Project Officer
John F. Martin
Resource Extraction and Handling Division
Industrial Environmental Research Laboratory
Cincinnati, Ohio 45268
INDUSTRIAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U. S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
This report has been reviewed by the Industrial Environmental
Research Laboratory-Cincinnati, U.S. Environmental Protection
Agency, and approved for publication. Approval does not signify
that the contents necessarily reflect the views and policies of
the U.S. Environmental Protection Agency, nor does mention of
trade names or commercial products constitute endorsement or
recommendation for use.
ii
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FOREWORD
When energy and material resources are extracted, processed, con-
verted, and used, the related pollutional impacts on our environ-
ment and even on our health often require that new and increasingly
more efficient pollution control methods be used. The Industrial
Environmental Research Laboratory - Cincinnati (lERL-Ci) assists
in developing and demonstrating new and improved methodologies that
will meet these needs both efficiently and economically.
This report contains an assessment of air emissions from the crushed
stone industry. This study was conducted to provide sufficient in-
formation for EPA to ascertain the need for developing control tech-
nology in this industry. Further information on this subject may be
obtained from the Extraction Technology Branch, Resource Extraction
and Handling Division.
David G. Stephan
Director
Industrial' Environmental Research Laboratory
Cincinnati
111
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PREFACE
The Industrial Environmental Research Laboratory (IERL) of the
U.S. Environmental Protection Agency (EPA) has the responsibility
for insuring that pollution control technology is available for
stationary sources to meet the requirements of the Clean Air Act,
the Water Act and solid waste legislation. If control technology
is unavailable, inadequate, uneconomical or socially unacceptable,
then financial support is provided for the development of the
needed control techniques for industrial and extractive process
industries. Approaches considered include: process modifications,
feedstock modifications, add-on control devices, and complete pro-
cess substitution. The scale of the control technology programs
ranges from bench- to full-scale demonstration plants.
IERL has the responsibility for developing control technology
for a large number (>500) of operations in the chemical and re-
lated industries. As in any technical program, the first step
is to identify the unsolved problems. Each of the industries is
to be examined in detail to determine if there is sufficient
potential environmental risk to justify the development of con-
trol technology by IERL. This report contains .the data necessary
to make that decision for the crushed stone industry.
Monsanto Research Corporation (MRC) has contracted with EPA to
investigate the environmental impact of various industries which
represent sources of pollution in accordance with EPA's responsi-
bility as outlined above. Dr. Robert C. Binning serves as MRC
Program Manager in this overall program entitled."Source Assess-
ment," which includes the investigation of sources in each of four
categories: combustion, organic materials, inorganic materials,
and open sources. Dr. Dale A. Denny of the Industrial Processes
Division at Research Triangle Park serves as EPA Project Officer
for this series. This study of crushed stone was initiated by
lERL-Research Triangle Park in March 1975; Mr. David K. Oestreich
served as EPA Project Leader. The project was transferred to the
Resources Extraction and Handling Division, lERL-Cincinnati, in
October 1975; Mr. John F. Martin served as EPA Project Leader
through completion of the study.
IV
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ABSTRACT
This report describes a study of air emissions from crushed stone
production. The potential environmental effect of the source is
evaluated.
Crushed stone production in 1972 was 1.07 x 108 metric tons
•(1.18 x 10 8 tons), 68% of which .was traprock. Contingency fore-
casts of increased crushed stone demand in the year 2000 range
from 300% to 490% of 1968 levels.
Atmospheric emissions of respirable particulates (<7- ym) occur
in the two areas of operation: mining from the open quarry, and
processing at the crushing and screening plant. The emission
factor for respirable particulates from the entire facility is
3.25 g/metric ton (0.007 Ib/ton) ±2.54 g/metric ton (0.005 Ib/ton)
at the 95% confidence level. Free silica comprises 1.6% of these
particulates-by weight. The primary crusher and quarrying unit
operations account for 73.5% of the respirable particulates. The
emission factor for total particulates is 28.4 g/metric ton (0.57
Ib/ton) ±24.5 g/metric ton (0.049 Ib/ton) at the 95% confidence
limit.
In order to evaluate'the potential environmental effect of crushed
stone plants> a severity factor was defined as the ratio of the
maximum ground level concentration of an emission to the ambient.
air quality standard for criteria pollutants and to a modified
threshold limit value for other pollutants. The maximum severity
factors for a representative crushed stone plant are 0.03 and 0.83
when the emissions are treated as respirable particulates and free
silica, respectively.
The population affected above a severity of 0.1 is zero for respi-
rable particulates and 172 persons for free silica particulates.
Total particulate emissions from crushed stone production account
for no more than 0.02% of the total national particulate emissions.
No emerging technology of specific importance to air pollution
control in the crushed stone industry was found in this study.
This report was submitted in partial fulfillment of Contract No.
68-02-1874 by Monsanto Research Corporation under the sponsorship
of the U.S. Environmental Protection Agency. This report covers
the period March 1975 to February 1976, and work was completed as
of July 1977.
v
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CONTENTS
Foreword iii
Preface iv
Abstract v
Figures yii
Tables viii
Abbreviations and Symbols .^
Conversion Factors and Metric Prefixes xii
I Introduction 1
II Summary ' 2
III Source Description 6
A. Process Description 6
1. Emission Sources 6
2. Source Definition 6
B. Factors Affecting Emissions 8
C. Geographical Distribution 9
IV Emissions 12
A. Selected Pollutants 12
B. Characteristics 13
C. Definition of the Representative Source 18
D. Source Severity 19
V Control Technology 20
A. State of the Art 20
B. Future Considerations 20
VI Growth and Nature of the Industry 25
A. Present Technology 25
B. Emerging Technology 25
C. Production Trends 25
References 28
Appendices . ' ;
A. Literature Survey 32
B. Sampling Equipment, Procedures and Analysis 38
C. Sampling Results and Error Analysis 58
D. Comparison of Emission Results with Previous
Studies 70
E. Source Severity Calculations 73
Glossary 76
vii
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FIGURES
Number Page
1 'Production of crushed stone 7
2 Trends in the production of crushed stone, in
the U.S. 26
3 Mean trend-projection for crushed stone 26
B-l High volume sampling arrangement -of high volume
samplers labeled S0, Si, S2, S3, and S^ 39
B-2 Flow chart of atmospheric stability class
determination 41
B-3 Fugitive dust sampling worksheet 42
B-4 Sampling apparatus 48
viii
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TABLES
Number . . Page
1 Mass Emissions from Crushed Stone Operations 4
2 Crushed Stone Production and Population Densities
by State 10
3 Emission Factors for Crushed Stone Operations 15
4 Standard.Deviations and 95% Confidence Intervals
for Emission Factors 16
5 Emission Factors for Fibers, NO and CO • 16
2C
6 State and Nationwide ParticUlate Emission Burdens
from the Production of Crushed Stone 17
7 Elemental Analysis of Emissions -from Crushed Stone
Operations . ' 18
B-l Placement of Samples Downwind of Obstructions 40
B-2 Open Sources Sampling Guidelines 40
B-3 Fugitive Dust Sampler and Meteorplogical Data Log 45
B-4 Continuous Function for Lateral Atmospheric
Diffusion Coefficient a 47
B-5 Continuous Function for Vertical Atmospheric
Diffusion Coefficient a 47
z
B-6 Field Data Form 49
B-7 Explanation of Field Data Form Terms 50
C-l Production of Crushed Stone - Plant A 60
C-2 Production of Crushed Stone - Plant B 62
C-3 Elemental Analysis of Emissions from Crushed
Stone Quarries 67
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TABLES (continued)
Number Page
C-4 Free Silica Analysis from Crushed Stone Quarries 68
C-5 Fiber Analysis from Crushed Stone Quarries 68
D-l Emission Factors Obtained from Two Studies 71
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ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
A1
A, D, E, F
b
D
Df
DS
Dt
E '
Ed
Ei
ER
EU
exp
9
H
m1
M
N
P
Q
Qi
Qf
S
Sp
S1
So/ Si/ 82, 83, Sij
Sn
— cross-sectional area of falling
granules
— specific distances for high volume
samplers from x axis
— width of a conveyor belt
— representative distance from
the source
— diameter of a fiber
— distance at which the source
severity equals 0.1
— dosage
— emission factor
— emission factor for drilling
operation
— emission factor for loading operation
— emission factor for respirable
particulate
— emission factor for unloading
operation
— natural log base, e = 2.72, a
constant
— gravitational acceleration
— height of material fall
— slopes used in calculating distances
to samplers
— conveyor belt load
— model used for field data
— number of sampler readings
—• production rate of crushed stone
— emission rate
— initial airflow rate
—' final airflow rate
— amount of respirable dust formed
— filtration area divided by counting
field area
— source severity
— severity of free silica particulate
— atmospheric stability class
— high volume sampler locations
— n-th high volume sampler locations
XI
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ts — sampling "
TLV — threshold limit value
u — mean wind speed
Ub — linear speed qJ: a conveyor belt
V, Va -- air volume sampled
Wi — initi alt ;;{tareifc: weight of filter
Wf — final weight of filter
x^, y^ — Cartesian coordinates used to
relate position of the ith sampler
to the source
X, X. — downwind distance from source
along the dispersion centerline
X1 — any average calculated value
Y, Y. -- lateral distance from dispersion
centerline to sampler
Z — vertical distance from the X-
Y plane of the source to the
sampler plane
SYMBOLS
a — angle defined for use in calculating
sampler positions
9 — wind azimuth angle with respect
to y axis
IT — a constant, 3.14
PC — material density of coal
a — overall standard deviation
a •— horizontal standard deviation
y of plume dispersion
CTZ — vertical standard deviation of
plume dispersion
en — estimated population standard
deviation from sampling for X
a2 — additional standard deviation
in calculation of Q from X
X — downwind concentration
Y. — concentration at coordinate location
(Xf Y, 0)
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CONVERSION FACTORS AND METRIC PREFIXES
To convert from
centimeter -(cm)
centimeter2 (cm2)
centimeter3 (cm3)
degree Celsius (°C)
kilogram (kg)
kilogram (kg)
kilometer2- (km2)
meter (m)
meter (m)
meter3 (m3)
meter3 (m3)
meter/second (m/s)
metric ton
millimeter2 (mm2)
pascal (Pa)
radian (rad)
Prefix
kilo
centi
milli
micro
Symbol
k
c
m .
Vi
CONVERSION FACTORS
to
Multiply by
1.000 x 10°
1.550 x 10"1
6.102 x 10~2
t0p =1.8
2.204
angstrom
inch2
inch3
degree Fahrenheit
pound-mass (Ib mass
avoirdupois)
ton (short, 2,000 Ib mass) 1.102 x 10"3
2.591
3.281
6.215 x I0~k
3.531 x 101
1.000 x 103
2.237
2.205 x 103
mile2
foot
mile
foot3
liter
miles/hr
pound-mass
inch2
pound-force/inch2 (psi)
degree (°)
METRIC PREFIXES
Multiplication
factor
1.550 x 10 3
1.450 x 10~4
5.730 x 101
Example
10C
10'
10'
-2
-3
10
-6
1 kPa = 1 x 10 pascals
1 cm = 1 x 10~2 meter
1 mg = 1 x 10~3 gram
1 ym = 1 x 10" 6 meter
32
Metric Practice Guide. ASTM Designation E 380-74, American Society for
Testing and Materials, Philadelphia, Pennsylvania, November 1974. 34 pp.
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SECTION I
INTRODUCTION
The conversion of naturally occurring stone deposits into
crushed stone involves mining from open.quarries and processing
for size reduction and classification. Air pollution
is produced by individual sources (unit operations) during
mining, processing, and material transfer activities.
An investigation of the crushed stone industry was conducted
to provide a better understanding of the distribution
and characteristics of the air pollution emissions than
was available in the literature. Data collection emphasized
the accumulation of sufficient information to ascertain
the need for developing control technology.
This document contains information ons
• Emission sources and composition
• A method to estimate the emission levels due to crushed
stone unit operations
• Geographical distribution of crushed stone facilities
• Hazard potential of emissions
• Severity of emissions
• Types of control technology used and proposed
• Trends in crushed stone production and their effects
on emission levels
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SECTION II
SUMMARY
The crushed stone industry converts naturally occurring stone
deposits into a crushed stone form for use in the construction
industry (81% of the output). Crushed stone, as interpreted
in this study, includes: traprock, calcareous marl, shell
marble, mica schist, slate, and other miscellaneous stone
excluding granite, limestone, dolomite, sandstone, quartz, and
quartzite. Dimension stones (stones >_ 0.6 m in length and
width) are also excluded. Traprock accounted for 68% of the
crushed stone production of 1.07 x 108 metric tons3 (1.18 x
108 tons) at 1,009 quarries in 1972. Contingency forecasts of
increased crushed stone demand in the year 2000 range from 300%
to 490% of 1968 levels.
Atmospheric emissions of respirable (
-------
A representative crushed stone plant has a production rate of
454 metric,tons/hr (500 tons/hr) and emits respirable particu-
lates at a rate of 1.48 kg/hr (3.26 Ib/hr) and total particulates
at 12.9 kg/hr (28.4 Ib/hr). The representative distance to the
boundary is 410 m. The maximum severity for respirable particu-
lates is 0.03. The population affected above severity of 0.1
is thus zero. The maximum severity for free silica particulates
is 0.83 with an affected population of 172 persons for severity
>0.1 and zero persons for severity >_1.0. Maximum severities and
mass emissions for each unit operation and pollutant are summa-
rized in Table 1 on both a national and a representative plant
basis.
Total particulate emissions from crushed stone production account
for no more than 0.6% of the overall particulate emissions in any
state and 0.02% of the total national particulate emissions.
By 1978, the ratio of total national particulate emissions, with
the best available control technology applied, to the 1972 emis-
sions level is expected to be 0.55.
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TABLE 1. MASS EMISSIONS FROM CRUSHED STONE OPERATIONS
Total
U.S. total,
Unit metric tons/
operation yr
Blasting
Wet drilling
Primary crushing
and unloading
Secondary crushing
and screening
Tertiary crushing
and screening
Fines crushing
and screening
Conveying
Loading trucks
Unloading trucks
Transport on
wetted roads
Quarrying
TOTAL3
5.6
17
1,400
66
39
9.9
180
18
14
120
1,100
2,900
^articulates
Represen-
tative
plant,
kg/yr
5.5
17
1,400
65
38
9.7
180
17
13
120
1,100
3,000
% of Total
emissions
from all
operations
0.19
0.59
48
2.3
1.3
0.34
6.2
0.62
0^48
4.1
38
100
Respirable particulates
U.S. total,
metric tons/
yr
0.94
1.7
140
36
7.1
1.6
12
4.9
5.8
22
112
340
Represen-
tative
plant,
kg/yr
0.9
1.7
140
36
7.0
1.6
12
4.8
5.7
22
110
340
% of Total
emissions
from all
operations
0.28
0.50
41
11
2.1
0.47
3.5
1.4
1.7
6.5
32
100
U.S. total,
metric tons/
Severity yr
0.000081
0.00015
0.012
0.0032
0.00061
0.00014
0~ 0010
0.00042
0.00050
0.0019
0.0097
0.03
0.015
0.028
. 2.3
0.58
0.11
0.026
0.19
0.077
0.092
0.35
1.8
5.6
Free silica
Represen-
tative
plant,
kg/yr
0.02
0.03
2.3
0.57
0.11
0.03
0.19
0.08
0.09
0.34
1.8
5.6
% of Total
emissions
from all - ,
operations Severity
0.27
0.-50
41
: 10
', 2-° .
: 0.46
-
3.4 /
"~ 1.4
•- '< 1.6
6.2
. . 32~
100
0.0022^
0.0041
0.34
,
0.087 -
0.017 '
^
0.00038 1
0.029
0.012
0.014 '•
0.052-
0.27 ~
0.83
(continued)
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TABLE 1 (continued)
Ul
Unit
operation
Blasting
Wet drilling
Primary crushing
and unloading
Secondary crushing
and screening
Tertiary crushing
and screening .
Fines crushing
and screening
Conveying
Loading trucks
Unloading trucks
Transport on
wetted roads
Quarrying
a
TOTAL
U.S. total,
metric tons/
yr
300
C
C
C
C
_C
_C
C
c
c
Q
300
NOx
Represen-
tative
plant,
kg/yr Severity
300 0.09 .
_C _C
_C _C
C - C
_c _c
_c _c
c c
' c c
c c
c c
c c
300 0.09
U.S. total,
metric tons/
yr
180
C
C
_C
C
c
c
_c
c
£
-
Q
180
CO • • .
Represen-
tative
plant,
kg/yr Severity
180 0.00017
C C
C C
C C
C C
C C
_c _c
_c _c
c c
c c
c c
180 0.00017
U.S. total, ;.-.
1012 fibers/yr:V :
37
67
5,600
1,400
280
62
480
190
230
850
4,400
13,600
Fibers
Represen-
tative
plant,
.'; 10 12 fibers/yr
V'"
0.04
0.07
5.5
1.4
0.28
0.06
0.47
0.19
0.23
0.84
4.3
13
Severity
_b
_b
0.008
0.002
_b
_b
_b
_b
_b
t,
0.006
0.016
Values may not equal total due to reporting in significant figures.
Negligible; <0.001.
No species emitted from the unit operations shown.
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SECTION III -
SOURCE DESCRIPTION
A. PROCESS. DESCRIPTION
. 1. Emission Sources
The production of crushed stone refers to' the conversion of
stone deposits into a crushed stone form through a series of
unit operations (see Figure 1). These operations are divided
into two activities: mining and processing.
Mining refers to the acquisition of the stone from the stone
deposits. These deposits are first loosened through wet drilling
(for charging of explosives) and blasting with ANFO (ammonium
nitrate and fuel oil). The explosion causes the release of
gaseous and particulate pollutants. Quarrying, which releases
dust to the atmosphere, involves loading the blasted material
by front-end loader or shovel onto trucks or conveyors for trans-
port to the processing plant.
Processing refers to all activities at a plant area, generally
located near the quarry, where the stone is size reduced and
classified through a series of screening towers and crushers.
After primary crushing, material is conveyed to.the top of a
screening tow.er and dropped through the screens. Undersize
stone is stockpiled, and oversize stone is crushed and conveyed
to the next tower for further processing. These physical acti-
vities generate fugitive particulate emissions. Additional
dust is created by gravity loading undersize material into
trucks beneath the tower. These trucks unload in the stock-
pile area where customer trucks are filled by front-end loaders.
These activities also create fugitive dust, and all occur on
unpaved roads which, even wetted, also contribute to the emis-
sions.
2. Source Definition
The definition of crushed stone used in this study is much
narrower in scope than that used by the Bureau of Mines. Crushed
stone is defined herein as traprock, calcareous marl, shell
marble, mica schist, slate, and miscellaneous crushed stones,
excluding sandstone, quartz, quartzite, granite, limestone dolo-
mite, and dimension stones (stones >0.6 m in length and width.).
-------
MINING
PROCESSING
QUARRYING
Figure 1. Production of crushed stone.
-------
The term traprock pertains to all dark, dense, and fine-grained
igneous stone deposits. Calcareous marl is a crumbly soil con-
taining calcium carbonate. Shell marble is a coarse-grained
metamorphic stone deposit produced by the action of heat and
pressure on limestone and dolomite. Mica schist is derived
from phyllite, a stone deposit that forms slightly more intense
metamorphism than is needed to produce slate. Slate is a meta-
morphic rock formed by low-grade metamorphism of shale which,by
itself, is a fine-grained sedimentary rock composed of clay or
silt-sized particles (1)..
B. FACTORS AFFECTING EMISSIONS
Calculation of the severity of the source emissions and the
burden on the state and national emission levels necessitates a
knowledge of the emission rate for every crushed stone facility
in the U.S. The large number of facilities and the diversity of
operations made it impractical to conduct emission measurements
on a source-by-source basis. All production at a crushed stone
facility passes through the primary crusher. Thus, a method was
developed to derive an emission factor based on the grams of
respirable particles emitted per metric ton of crushed stone
processed using the primary crusher as a reference. The emis-
sion rate for each of the source types was then estimated as
the product of this emission factor and the crushed stone pro-
duction rate, expressed as metric tons per hour. The relation-
ship can be stated as:
Q = E x P (1)
where Q = emission rate of particulates, g/hr
E = emission factor for particulates, g/metric ton
P = production rate of crushed stone, metric tons/hr
The overall emissions from crushed stone facilities are due to
drilling, blasting, loading, crushing, screening, unloading,
transport, and conveying. Emissions from all of these unit
operations except blasting are influenced by particle size dis-
tribution, rate of handling, moisture content of the handled
material, and type of equipment used. A detailed literature
survey was conducted to obtain published data on the extent to
which various factors influence the overall emissions, and on
the relative contributions of the unit operations to overall
emissions (see Appendix A). Lack of quantitative data necessi-
tated on-site sampling to develop an emission factor. High
(1) Arem, J. Rocks and Minerals. Ridge Press, Inc., New York,
New York, 1973. 160 pp.
8
-------
volume sampling procedures (see Appendix B) were utilized to
quantify the quarrying emissions, whereas portable, on-the-spot
measurements were taken to identify and differentiate the emis-
sions from the individual processing operations.
C. GEOGRAPHICAL DISTRIBUTION
In 1972 the 1,009 crushed stone facilities in the U.S. produced
1.07 x 108 metric tons (1.18 x 108 tons) of stone (personal
communication with Mrs. Dunn, U.S. Department of Interior,
Bureau of Mines, Washington, D.C., 27 June 1975). In Table 2 (2),
New Jersey ranks first in production with 1.46 x 107 metric tons
(1.61 x 107 tons), followed by Washington, Oregon, Louisiana,
Connecticut, California, Massachusetts, and Pennsylvania. Togeth-
er these eight states account for 66.5% of the total crushed
stone production in the U.S. Traprock makes up 68% of total
production (2).
Geographically, the crushed stone industry is located near the
crushed stone deposits and close to the place of end use (i.e.,
rapidly expanding urban areas and areas where large-scale public
and private works are under construction). The population den-
sities of the states where crushed stone deposits are located
are also listed in Table 2.
(2) Drake, H. J. Stone. 1973 Bureau of Mines Minerals Year-
book, U.S. Department of the Interior, Bureau tof Mines,
Washington, D.C., 1973. 19 pp.
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TABLE 2. CRUSHED STONE PRODUCTION AND POPULATION
DENSITIES BY STATE (2)
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Georgia
Hawaii
Idaho
Indiana
Iowa
Kansas
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Production,
10 3 metric tons
1,925
563
1,522
4,911
7,706
854
7,720
871
3,426
2,807
249
23
531
8,337
798
4,506
6,344
865
814
650
518
2,089
1,008
436
14,620
1,152
2,756
5,553
-b
5
1,277
9,734
6,232
2,671
2
175
5,168
823
1,827
5,368
a
(10.3 tons)
(2,122)
(621)
(1,678)
(5,413)
(8,494)
(941)
(8,510)
(960)
(3,776)
(3,094)
(274)
(25)
(585)
(9,190)
(980)
(4,967)
(6,993)
(954)
(897)
(717)
(571)
(2,303)
(1,111)
(481)
(16,115)
(1,270)
(3,038)-
(6,121)
-b
(6)
(1,408)
(10,730)
(6,870)'
(2,944)
(2)
(193)
(5,697)
(907)
(2,014)
(5,917)
Population
density,
persons/km2
27
0.2
7
15
50
9
240
31
49
4
57
20
11
30
12
177
274 '
60
' 18
18
27
2
2
32
366
3
145
39
2
102
15
9
103
' 34
2
38
17
5
19
46
(continued)
10
-------
TABLE 2 (continued).
State
Washington
Wisconsin
Wyoming
Undistributed
Production ,
10 3 metric tons
10,413
1,004
403
-21,682
a
r
(103 tons)
(11,478)
(1,107)
(444)
(-23,900)
Population
density,
persons/km2
20
31
1
Total
106,974
.(117,554)
Crushed stone production per state = stone production per
state less the production of other stones per state.
Not available.
* i •
'Represents the difference between U.S. total and individual
states total as reported in Reference 2; negative number
represents the net difference in discrepancies found in
the reference due to the method of reporting (disclosure
of individual plant capacities).
11
-------
SECTION IV
EMISSIONS
A. SELECTED POLLUTANTS
The major pollutant emitted from the production of crushed
stone is respirable (<7-ym geometric mean diameter) particulate
matter. This particulate contains free silica, the crystalline
silicon dioxide which is mostly quartz, tridymite and cristo-
balite.
Quartz may be colorless or white, rose, violet, brown or almost
any hue depending on its impurities. Tridymite forms from
quartz above 870°C into white or colorless orthorhombic crystals,
while cristobalite forms above 1,470°C into white cubic crystals.
Quartz is usually present as a mineral constituent of rocks,
while tridymite and cristobalite usually occur together as
abundant high-temperature silicate minerals in the volcanic
rocks of California, Colorado and Mexico (3).
A pulmonary fibrosis called silicosis develops from the prolonged
inhalation of free silica dusts. The action of this dust in.
.the lungs results in the production of a diffuse, nodular
fibrosis. This condition is progressive and may continue to
increase for several years after exposure is terminated. The
most common symptom of uncomplicated silicosis is shortness
of breath on exertion, sometimes accompanied by dry cough.
Where the disease advances, the shortness of breath becomes
worse and the cough more troublesome. Further progress of
the disease results in marked fatigue, loss of appetite, pleu-
ritic pain, and total incapacity to work. Extreme cases may
eventually cause death due to the destruction of. the lung
tissues (4). . •
(3) Occupational Exposure to Free Silica, Criteria for
Recommended Standard. Publication No. NIOSH 75-120, U.S.
Department of Health, Education and Welfare, Washington,
D.C., 1974. 121 pp.
(4) Sax, N. I. Dangerous Properties of Industrial Materials,
3rd Edition. Reinhold Book Corp., New York, New York,
. 1968. pp. 1088-1089.
12
-------
The American Conference of Governmental Industrial Hygienists
(ACGIH) has suggested a TLV® (threshold limit value) for res-
pirable particulates as shown in' Equation 2:
TLV = % quartz + 2 (f°r % qUartZ >1%) . (2)
where TLV = threshold limit value, mg/m3
% quartz = percent of quartz in respirable dust
Respirable particulates with less than 1% quartz are termed
"inert", and"a TLV of 10 mg/m3 is suggested for these (5).
The criteria .document on crystalline silica recently published
by the National Institute of Occupational Safety and Health
(NIOSH) states that occupational exposure shall be controlled
so that no worker is exposed to a time-weighted average con-
centration of free silica greater than 50 ug/m3 as determined
by a full shift sample for up to a 10-hour workday, 40-hour
workweek (3). In addition, particulate matter is one of the
air quality criteria pollutants and has a 24-hour primary ambient
air quality standard of 260 ug/m3.
Fibers are also emitted from crushed stone operations. These
fibers were not analyzed in detail with respect to their chemical
compositions; for the purposes of source assessment they were
treated as asbestos fibers. Upon prolonged inhalation., asbestos
fibers have been associated with pulmonary and pleural fibrosis.
The disease, asbestosis, is characterized-by diffuse intersti-
tial fibrosis in the lungs. Asbestos fibers have also been
considered etiological factors in pleural calcification, bron-
chogenic carcinoma, and mesothelial tumors. A TLV of five
fibers/ml has been recommended for asbestos fibers by the ACGIH.
Nitrous oxides and carbon monoxide are emitted from the blasting
operation. These pollutants have threshold limit values of
9 mg/m3 and 55 mg/m3, respectively. Both of these are criteria
pollutants with primary air quality standards of 100 yg/m3
(0.05 ppm) for the annual arithmetic mean for nitrogen dioxide
and 10 mg/m3 (9 ppm) for an 8-hour average concentration for
carbon monoxide.
B. CHARACTERISTICS
The mean emission factor for respirable particulate emissions
from.crushed stone production is 3.25 g/metric ton of crushed
stone processed through the primary crusher with a standard
(5) Documentation of Threshold Limit Value (TLV) for Substances
in Workroom Air. Adopted by the American Conference of
Governmental Industrial Hygienists, 1972. 97 pp.
13
-------
deviation of 0.33 g/metric ton and a 95% confidence interval-
of 1.47 g/metric ton. The mean emission factor for total
particulate emissions is 28.36 g/metric ton with a standard
deviation of 3.4 g/metric ton and a 95% confidence interval
of 22.2 g/metric ton. .The primary crusher and quarrying opera-
tions account for 73.5% of the respirable particulate emissions
and 84.2% of the total particulate emissions. Table 3 gives
the emission factors for respirable and total particulate
emissions from the various unit operations. The standard devia-
tions and the 95% confidence levels are given in Table 4.
The emission factors determined for this report/ based on samples
taken about 35 m ('vLOO ft) away from the source, are about
two orders of magnitude less than those reported in previous
studies. Dust loading measurements taken at the inlet of a
baghouse system were used to determine the previously reported
emission factors. By virtue of its high airflow, a baghouse
system pulls in large particles that otherwise would not be
airborne at all. Thus an emission factor based on dust loading
at a baghouse inlet is an inflated value. Appendix D discusses
this subject in detail.
Table 5 lists the emission factors for fibers, nitrogen oxides,
and carbon monoxide.
The aforementioned emission factor for total particulates was
used to estimate statewide emission rates as the product of
the emission factor and the crushed stone processing rate for
that state. The state emission burden is thus calculated as
the percent contribution of particulate emission rates for
crushed stone processing in a state to the overall particulate
emissions in that state. Table 6 displays the state and nation-
wide emission burdens (6).
It can be seen that the emissions of particulates due to crushed
stone processing contribute no more than 0.6% to total particu-
lates in any state in the U.S. and 0.02% of the nationwide
emissions burden.
An analysis of the particulate emissions from crushed stone
operations showed that free silica is the only hazardous
component. Free silica was found to constitute 1.57% (by
(6) 1972 National Emissions Report. U.S. Environmental'Protec-
tion Agency. Publication No. EPA-450/2-74-012, Research
Triangle Park, North Carolina, June 1974. 422 pp.
• ' 14
-------
TABLE 3. EMISSION FACTORS FOR CRUSHED STONE OPERATIONS
Ui
% of Total .
respirable . , % of Total
Respirable particulates Total particulates
particulates, from all crushed particulates, from all crushed
Unit operation mg/metric ton stone operations ' mg/metric ton stone operations3
Blasting
Drilling (wet)
Quarrying
Primary crushing
and unloading
Secondary crushing
and screening
Tertiary crushing
and screening
Fines crushing
and screening
Conveying
Loading trucks
Unloading trucks
Transport (wet)
Total
8.8 .
16.0
1,050
1,340
342
66.5
14.7
113
45.3
53.8
202
3,250
0.27
0.49
32.3
41.2
10.5
2.05
0.45
3.48
1.39
1.65
6.21
52.2 0.18
158 . 0.56
10,500 37.02
13,400 47.2
619 2il8
362 1.28
91.8 0.32
1,730 6.10
166 0.58
127 . 0.45
1,150 4.05
28,400
Respirable
particulate,
% of total
particulates from
unit operation
17
10
10
10
55
.18
16
7
68
42
18
llb
a
Rounded off; does not add to 100%.
rj '- ;•"- -
Total respirable particulates as percent of total particulates from all unit operations.
-------
TABLE 4. STANDARD DEVIATIONS AND 95% CONFIDENCE INTERVALS FOR EMISSION FACTORS
Respirable particulate
emission factor
Standard
deviation ,
Unit operation mg/nietr'ic tori
Blasting
Drilling
Quarrying
Primary crushing
and unloading
Secondary crushing
and screening
Tertiary crushing
and screening
Fines crushing
and screening
Conveying
Loading trucks
Unloading trucks
Transport (wet)
Overall emissions
1.4
8.0
210
141
36.1
7.0
95% Confidence
interval ,
mg/metric tori
12.6
12.6
399
1,270
324
63
Total particulate
emission factor
Standard
deviation,
nig/metric ton
8.4
79.0
2,100
2,402
111
65.0
95% Confidence
interval,
mg/metric ton Remarks
74.6
125
3,990
21,600
997
583
Based on coal mining studies
Based on granite
Based on granite
Taken as similar
crusher
Sampling results
Taken as similar
studies
studies
to secondary
to
secondary crusher
12.0
11.3
24.8
29.4
202
328
106
102
222
264
372
1,470
73.8
173
153
117
1,150
3,410
662
1,560
1,370
1,050
2,120
22,200
Sampling results
Based on granite
Taken as similar
trucks
Sampling results
Based on granite
studies
to unloading
studies
Unpaved road, vehicular traffic.
TABLE 5. EMISSION FACTORS FOR FIBERS, NOX AND CO
Pollutant
Emission factor
Fibers 128 x 10s fibers/metric ton
NOX 2.85 g/metric ton
CO 1.68 g/metric ton
-------
TABLE 6. STATE AND NATIONWIDE PARTICULATE EMISSION BURDENS
PROM THE PRODUCTION OF CRUSHED STONE (6)
State
Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Georgia
Hawaii
Idaho
Indiana
.Iowa
Kansas
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont-
Virginia
Washington
Wisconsin
Wyoming
U.S-. Total
Overall
particulate
emissions ,
10 3 metric tons/yr
If 180
13.9
72.7
138
1,010
201
40.1
404
61.6
55.5
748
216
348
380
49.2
495
96.2
706
392
50.6
1,150
872
305
86.6
152
103
160
481
79.0
1,770
93.6
169
1,810
199
52.3
410
549
71.7
14.6
477
162
412
75.4
17,8 2d .
Particulate emissions Contribution from
due to production of production of crushed
crushed stone, stone to overall state
metric tons/yr emissions, %
55
16
43
139
219
24
219
25
97
80
7
0.7
15
236
23
128
180
25
23
18
15
59
29
12
415
33
78
157
_b
_C
36
276
177
76
_C
5
147
. 23
52
152
295
28
11
3,649
_a
0.12
0.06
0.10
0.02
0.01.
0.55
_a
0.16
0.14
_a
_a
_a
0.06
0.05
0.03
0.19
_a
_a
0.04
_a
_a
0.01
0.01
0.27
0.03
0.05
0.03
_b
_a
0.04
0.16
0.01
0.04
_a
_a
0.03
0.03
0.36
0.03
0.18
_a
0.01
0.02
Negligible, <0.01%.
Not available.
£
Negligible, <1,0 metric ton/yr.
^U.S. total includes certain area sources not included in individual state inventories.
17
-------
weight) of the particulates (see Table C-3, Appendix G). Other
constitutents are inert and constitute 98.43% (by weight).
Table 7 gives the elemental analysis of. emissions from crushed
stone operations.
TABLE 7. ELEMENTAL ANALYSIS OF EMISSIONS FROM
CRUSHED STONE OPERATIONS
Range of composition,
Element percent by weight
Silicon
Calcium
Sodium
Iron
Aluminum
Magnesium
Titanium
Tin
Chromium
Lead
Vanadium
Manganese
Copper
Nickel
Zirconium
Silver
Zinc
Molybdenum
Boron
3.0 to 35.3
2.4 to 11.8
3.0 to 18.9
1.5 to 16.3
1.5 to 16.3
0.3 to 2.4
0.2 to 0.7
0.01 to 0.2
0.01 to 0.5
0.10 to 0.6
0.02 to 0.1
0.02 to 0.09
0.03 to 0.12
. <0.006
<0.025
<0.025
<0.5
<0.24
<0.12
C. DEFINITION OF THE REPRESENTATIVE SOURCE
A traprock producing facility was chosen as representative
of the crushed stone industry for two reasons:
Traprock constitutes the majority (68%) of the crushed
stone output; and
• It is a dark igneous rock which may contain fibrous material
(such as asbestos); thus, it would show the worst case
of hazard potential for the crushed stone industry from
this material viewpoint.
Emissions due to crushed stone processing can be expressed
as stated earlier in Equation 1. The representative source
is defined as one that has the mean emission parameters; i.e.,
mean emission factor and mean production rate. Consultations
with industry experts showed that crushed stone plants have
production rates of from 90 metric tons/hr (^100 tons/hr) to
18
-------
1,080 metric tons/hr (1,190 tons/hr) with a mean of 454 metric .
tons/hr (^500 tons/hr).
The mean emission factor was determined by sampling two traprock
plants whose production rates are similar to that of the repre-
sentative plant (Appendix C). Thus the representative source
has an emission r-ate of 1.5 kg/hr for respirable particulates.
The sampled plants had an average area of 0.53 km2. The repre-
sentative distance to plant boundaries was taken as the radius
of a circle whose area is equal to the area of the plant.
For an area of 0.53 km2, this is equal to 410 meters. The
representative population density was taken as the mean popula-
tion density of the eight leading crushed stone producing states
(New Jersey, Washington, Oregon, Louisiana, Connecticut, Cali-
fornia, Massachusetts, and Pennsylvania) which account for
66.5% of crushed stone output. The representative population
density was determined to be 137 persons/km2.
D. SOURCE SEVERITY
The maximum source severity due to respirable particulate
emissions from the representative crushed stone facility is
0.03. (Severity calculations are given in Appendix E.) The
affected population is zero.
.The maximum source severity due to free silica emissions is
0.83. Emissions of free silica particles affect a population
of 172 persons at M10 meters for a severity greater than 0.1
and zero persons for a severity >1.0.
The maximum source severity due to fiber emissions is 0.02
and the affected population is zero.
19
-------
SECTION V
CONTROL TECHNOLOGY
A. STATE OF THE ART
The unpaved roads at crushed stone plants are frequently sprayed
with water or oil to control, air emissions. This is done in
compliance with a Department of Interior regulation designed
to keep dust levels in the plant below the threshold limit
values prescribed by the American Conference of Governmental
Industrial Hygienists. Thus the unpaved road emissions consti-
tute less than 6% of the overall plant emissions. If the un-
paved road emissions were uncontrolled, the overall plant emis-
sions would be about seven times the controlled value and unpaved
road contributions would constitute more than 85% of total plant
emissions.
Control techniques are not widely applied to emissions from
other sources such as crushing, screening, conveying, and stock-
piling. Some plants use a baghouse and/or wet suppression
systems to control dust emissions. Wet drilling is also employed
by some to reduce drilling emissions.
Since the amount of dust generated from the various operations
is dependent on the dryness of the material, any addition of
water is helpful in reducing emissions. Natural occurrences,
such as rain or snow, and in-process washing and spraying thus
control emissions.
B. FUTURE CONSIDERATIONS
A number of control techniques that may find application in con-
trolling emissions from crushed stone operations are discussed
below.
Dust emissions from dry percussion drilling operations can
be controlled by adding water, or water mixed with a surfactant,.
into the air used for flushing the drill cuttings from the
hole. Dilution ratios range from 800 to 3,000 parts of water
20
-------
to 1 part of surfactant. The proper amount of solution, about
0.026 m3/hra (7 gal/hr) for an 89-mm (3 1/2-in.) diameter hole,
causes the drill cutting to be blown from the hole as damp,
dust-free pellets (7) .
Water filled plastic bags with or without solid stemming material
(clay) are used for stemming dust emissions from blast holes.
This method reduces dust concentrations by 20% to 80% and explo-
sive consumption by about 10% (8). Pastes with a cellulose
or bentonite base can be used instead of liquids if the pastes
have "thixotropic" properties; i.e., they are gelatinous in
repose, but become liquid when vibrated.
Release of carbon monoxide, nitric oxide, and other gases such
as aldehydes and hydrogen can be curtailed by having a dry
blast hole and by carrying out the detonation properly to prevent
incomplete combustion.
Blasted stone is loaded into trucks by front-end loaders, creat-
ing dust emissions. Wetting of the broken stone with water
or water mixed with a surfactant will alleviate the dust emissions,
Emissions due to wind erosion during transport can be reduced
by covering the truck bed with a tarpaulin or wetting the surface
of theload with water or water mixed with chemicals.
A number of methods are available for more effectively control-
ling emissions from unpaved roads. Water application is effec-
tive, but about 5% to 8% moisture (by weight) must be achieved
to suppress the dust emissions (9). Additives such as calcium
chloride .can be used to reduce the surface tension of water
so that the dust can be wetted with less water. Calcium chlo-
ride can be applied at a cost of approximately $0.15/m2 treated
per year (7). A major problem here is the corrosion of vehicle
bodies and leaching by rain water or melting snow. More fre-
quent applications may be necessary during summer months.
al m3 = 1 meter3 = 1,000 liters.
(7) Jones,.H. R. Fine Dust and Particulates Removal. Noyes
Data Corporation, Park Ridge, Illinois, 1972. 307 pp.
(8) Grossmueck, G. Dust Control in Open Pit Mining and
Quarrying. Air Engineering, 10(25):21, July 1968.
(9) Dust Suppression. Rock Products, 75:137, May 1972.
21
-------
Another effective dust control method for unpaved roads is
to mix stabilization chemicals into the road surface to a depth
of about 20 mm to 50 mm (10). One cement company sprays a
solution of 4 parts of water and 1 part of a special emulsion
agent3 at the rate of approximately 0.009 m3/m (2 gal/yd2)
of road surface. Certain pretreatment measures such as working
the-road surface into a stiff mud are necessary to prevent
the binder in this emulsion agent from sticking to the vehicles.
Periodic maintenance such as a 1:7 emulsion agent/water solution
spray keeps the emulsion agent binder active. This dust control
program was found to give 3 years of service at a total cost
of $0.12/m2.
Mixing cutback asphalt into the road surface to a depth of
50 mm to 80 mm has been investigated in some counties in Iowa
(11). Such surface treatment reduces dust emissions, but it
requires periodic maintenance such as patching of the potholes.
Treating the road surface with oil once a month is another
efficient way to control unpaved road dust emissions. The •
cost for such applications is estimated to be $0.10/m2 treated
per year (12). However, a study conducted by the Edison Water
Quality Research Laboratory in New Jersey shows that 70% to
75% of the oil.applied moves from the surface of the road by
dust transport and runoff, and thus ecological damage may be
caused by the oil or its heavy metal constituents such as lead
(12). Furthermore, surface oiling requires regular maintenance,
as roads treated in this way develop potholes.
aCoheren, Golden Bears Division, Witco Chemicals Company.
(10) Significant Operating Benefits Reported from Cement Quarry-
Dust Control Programs. Pit and Quarry, 63(7):116, January
1971,
(11) Hoover, J. M. Surface Improvement and Dust Palliation
of Unpaved Secondary Roads and Streets, Final Report.
Publication No. ER-1, Project 856-S, Iowa State University,
Engineering Research Institute, Ames, Iowa, July 1973.
364 pp.
(12) Runoff of Oils from Rural Roads Treated to Suppress Dust.
Report No. R2-72-054, Edison Water Quality Research
Laboratory, Edison, New Jersey, October .1972. 29 pp.
22
-------
Lignin sulfonates, by-products from paper manufacture, are
also used to control dust emissions. One of the commercially
available lignin sulfonates3 was tested on a farm access road
at Arizona State University (13) . The method proved quite
successful, giving effective dust suppression for 5 years at
a cost of $0.47/m2 ($0.10/m2-year).
The best method for controlling dusts is to pave the road sur-
face, but this is impractical due to the high cost involved
and the temporary nature of crushed stone plants.
The simplest and least expensive means of controlling dust
from crushing, screening, conveying, and stockpiling is through
the use of wetting agents and sprays at critical points. Effi-
ciencies up to 95% can be achieved in these systems. A crushed
rock production plant uses a dust suppression system and a
chemical wetting agent.b Approximately 0.004 nr of concentra-
ted wetting agent is diluted 1,000 times by volume^with water
using an automatic proportioner. The solution is sprayed at
the top and bottom of cone crushers at the rate of 0.0042 m3
of solution per metric ton of material being crushed. This
system also helps in reducing dust emissions at transfer points,
screening operations, storage bins, and stockpiling.operations
(14). Such a system has many cost-saving advantages. It requires
no ducts, hooding, or other enclosures for crushers, screens,
or conveyor transfers. 'Since the equipment is in the open
the operators can see the entire material flow. The dust is
not collected so there is no solid waste disposal or water
pollution problem.
a
Orzan A, Crown Zellerbach Corporation.
Chem-Jet, Johnson-March Corporation.
(13) Bub, R. E. Air Pollution Alleviation by 'Suppression of
Road Dust. M.S.E. thesis, Arizona State University,
Tempe, Arizona, June 1968. 45 pp.
(14) Harger, H. L. Methods Used by Transit Mix Operators to
Meet Ai-r Pollution Control District Requirements. National
Sand and Gravel Association and Ready Mixed Concrete Assoc-
iation, April 1971. 22 pp.
23
-------
In a crushed stone plant, a baghouse is used to control dust
emissions from cone crushers, scalping screens, twin sizing
screens, and at the shuttle and transfer conveyors at an effi-
ciency of 99.8%. Anywhere from 2,722 kg to 5,443 kg of dust
is collected in a 10-hour day from a 182-metric ton/hr plant
(15). A baghouse does not control dust in stockpile areas
unless these areas are totally enclosed. Further, the dust
collected in the baghouse presents a solid waste problem.
The alternative disposal methods are to put the dust into settl-
ing basins or to incorporate it into a useful product which
may be sold. Depending on the type of material and the local
market conditions, such uses may include manufactured sand,
underslab fill, and asphalt filler (16).
(15) Trauffer, W. E. Main's New Dust-Free Crushed Stone Plant.
Pit and Quarry, 63(2):96, August 1970.
(16) Ozol, M. A., S. R. Locke, et al. Study to Determine the
Feasibility of an Experiment to Transfer Technology to
the Crushed Stone Industry. National Science Foundation,
Contract NSF-0826, Martin Marietta Laboratories, Baltimore,
Maryland, June 1974. 106 pp.
24
-------
SECTION VI
GROWTH AND NATURE OF THE INDUSTRY
A. PRESENT TECHNOLOGY
Present technological improvements in the crushed stone industry
include the use of larger and more efficient crushing and
screening units. Primary crushing is often done near the pit,
usually by jaw or gyratory crushers. Other crushing is
accomplished using cone or gyratory crushers. Horizontal screens
are generally used for size classification. The crushed and
classified stone is stored in open areas. In the larger and
more efficient plant, stone is drawn out through tunnels under
the storage piles and equipment is designed to blend any desired
mixture of sizes.
B. EMERGING TECHNOLOGY
No emerging technology of specific importance to air pollution
control in the crushed stone industry was found in this.study.
C. PRODUCTION TRENDS
Production of crushed stone from 1945 to 1968 increased at
a rate of 2.7% per year. Contingency forecasts for the year
2000 predict a mean growth rate of 4.25% per year. These growth
rates are reflected in Figures 2 and 3, respectively.
Production of crushed stone is tied very closely to activity
in the stone consuming industries. Since the construction
industry consumes more than 81% of the crushed stone output,
the production of crushed stone is associated chiefly with
the needs of this industry. By 1978 the total production
of crushed stone is forecast to be 1.37 x 108 metric tons.
With all available controls applied, total particulate emissions
in 1978 would be 1,679 metric tons (Appendix E). The 1972
level of emissions was 3,034 metric tons, based on uncontrolled
crushed stone facilities. The growth factor or ratio of 1978
to 1972 emissions is thus 0.55.
Transportation costs have a large effect on the production
trends of the crushed stone industry, since they constitute
a major part of the delivered cost of crushed stone. In many
25
-------
oo
I
O
o:
fc
8
7
6
5
4
3
2
1
1945 1950
1955 1960 1965 1970 1975
YEAR
Figure 2. Trends in the production/of crushed stone
in the United States.
3 -
o
1975 1980 1985 1990 1995 2000 2005
YEAR
Figure 3. Mean trend projection for crushed stone,
26
-------
cases, the processing plants are therefore located near the
point of use. However, local zoning and environmental regula-
tions, and depletion of urban deposits, may necessitate the
location of future processing plants away from the points of
use. This should increase the use of rail and barge transport
in order to hold down shipping costs. Truck haulage will still
remain important, especially for local delivery of crushed
stone. If rail and water systems are used for long hauls to
central distribution points, this may finally result in an
increase in the delivered price of crushed stone.
27
-------
REFERENCES
1. Arem, J. Rocks and Minerals. Ridge Press, Inc.,
New York, New York, 1973. 160 pp.
2. Drake, H. J. Stone.' 1973 Bureau of Mines Minerals Yearbook,
U.S. Department of the Interior, Bureau of Mines,
Washington, D.C., 1973. 19 pp.
3. Occupational Exposure to Free Silica, Criteria for
Recommended Standard. Publication No. NIOSH 75-120, U.S.
Department of Health, Education-and Welfare, Washington,
D.C., 1974. 121 pp.
4. Sax, N. I. Dangerous Properties of Industrial Materials,
3rd Edition. Reinhold Book Corp., New York, New York,
1968. pp. 1088-1089.
5. Documentation of Threshold Limit Value (TLV) for Substances
in Workroom Air; Adopted by the American Conference of
Governmental Industrial Hygienists, 1972. 97 pp.
6. 1972 National Emissions Report. U.S. Environmental
Protection Agency. Publication No. EPA-450/2-74-012,
Research Triangle Park, North Carolina, June 1974. 422 pp.
7. Jones, H. R. Fine Dust and Particulates Removal. Noyes
Data Corporation, Park Ridge, Illinois, 1972. 307 pp.
8. Grossmueck, G. Dust Control in Open Pit Mining and
Quarrying. Air Engineering, 10('25):21, July 1968.
9. Dust Suppression. Rock Products, 75:137, May 1972.
10. Significant Operating Benefits Reported from Cement Quarry
Dust Control Programs. Pit and Quarry, 63(7):116, January
1971.
11. Hoover, J. M. Surface Improvement and Dust Palliation
of Unpaved Secondary Roads and Streets, Final Report.
Publication No. ER-1, Project 856-S, Iowa State University,
Engineering Research Institute, Ames, Iowa, July
1973. 364 pp.
28
-------
12. Runoff of Oils from Rural Roads Treated to Suppress Dust.
Report No. R2-72-054, Edison Water Quality Research
Laboratory, Edison, New Jersey, October 1972. 29 pp.
13. Bub, R. E. Air Pollution Alleviation by Suppression of
Road Dust. M.S.E. thesis, Arizona State University,
Tempe, Arizona, June '1968. 45 pp.
14. Harger, H. L. Methods Used by Transit Mix Operators to
Meet Air Pollution Control District Requirements.
National Sand and Gravel Association and Ready Mixed
Concrete Association, April 1971. 22 pp.
15. Trauffer, W. E. Main's New Dust-Free Crushed Stone Plant.
Pit and Quarry, 63(2) :96, August 1970.
16. Ozol, M. A., S. R. Locke, et al. Study to Determine the
Feasibility of an Experiment to Transfer Technology to
the Crushed Stone Industry. National Science Foundation,
Contract NSF-0826, Martin Marietta Laboratories, Baltimore,
Maryland, June 1974. 106 pp.
17. Chaiken, R. F. Ammonium Nitrate-Fuel Oil Mixtures. In:
Toxic Fumes from Explosives. Publication No. PB 233 496,
Bureau of Mines, Washington, D.C., May 1974. 24 pp.
18. Blackwood, T. R., and P. K. Chalekode. Source Assessment
Document: Transport of Sand and Gravel. Contract
68-02-1320, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina. (Preliminary document
submitted to the EPA by Monsanto Research Corporation,
December 1974.) 87 pp.
19. Cheng, Lung. Formation of Airborne-Respirable Dust at
Belt Conveyor Transfer Points. American-Industrial Hygiene
Association Journal,.34:540-546, December 1973:
20. Cowherd, Chatten. Development .of Emission Factor for
Fugitive Dust Sources. Publication 1152, Midwest Research
Institute, Kansas City, Kansas. Presented at APCA
meeting, Denver, Colorado, June 1974. 175 pp.
21. Andresen, W. V. Industrial Hygiene Design in Raw Materials
Handling Systems. American Industrial Hygiene
Association Journal, 23(6):509-513, November-December
1962.
22. Blackwood, T. R., T. F. Boyle, T. L. Peltier, E. C.
Eimutis, and D. L. Zanders. Fugitive Dust from Mining
Operations. Contract 68-02-1320, Task 6, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina,
May 1975. p. 34.
29
-------
23. Turner, D. B. Workbook of Atmospheric Dispersion Estimates,
1970 Revision. Public Health Service Publication
No. 999-AP-26, U.S. Department of Health, Education, and
Welfare, Cincinnati, Ohio, May 1970. 84 pp.
24. Eimutis, E. C., and M. G. Konicek. Derivations of
Continuous Functions for the Lateral and Vertical
Atmospheric Dispersion Coefficients. Atmospheric
Environment, 6:859-863, March 1972.
25. Martin, D. 0., and J. A. Tikvart. A General Atmospheric
Diffusion Model for Estimating the Effects on Air Quality
of One or More Sources. Presented at the 61st Annual
Meeting of the Air Pollution Control Association, St.
Paul, Minnesota, June 23-27, 1968. 18 pp.
26. Aerospl Technology Committee. Guide for Respirable Mass
Sampling. American Industrial Hygiene Association Journal,
31:133, January-February 1970. '
27. Larsen, D. M., L. J. Von Doenhoff, and J. V. Crable.
The Quantitative Determination of Quartz in Coal Dust
by Infrared Spectroscopy. American Industrial Hygiene
Association Journal, 33:367-372, June 1972.
28. Freedman, R. W., S. Z. Toma, and H. W. Lang. On-Filter
Analysis of Quartz in Respirable Coal Dust by Infrared
Absorption and X-Ray Diffraction. American Industrial
Hygiene Association Journal, 35:411-418, July 1974.
29. Durken, T. M. Determination of Free Silica in Industrial
Dust. Journal of Industrial Hygiene and Toxicology,
28:217, February 1946.
30. Edwards, G. H. Comparison of X-Ray Diffraction, Chemical
(Phosphoric Acid), and Dispersion Staining Methods for
the Determination of Quartz. American Industrial Hygiene
Association Journal, 26:532, September-October 1965.
31. Freedman, R. W. Recent Advances in the Analysis of
Respirable Coal Dust for Free Silica, Trace Elements, and
Organic Constituents. Annals of the New York Academy of
Sciences, 200:7-16, December 1972.
32. Cares, J. W., A. S. Goldin, J. J. Lynch, and W. A. Burgess.
The Determination of Quartz in Airborne Respirable Granite
Dust by Infrared Spectrophotometry. American Industrial
Hygiene Association Journal, 34:298-305, July 1973.
30
-------
33. Gifford, F. A., Jr. Chapter 3 - An Outline of Theories
of Diffusion in the Lower Layers of the Atmosphere. In:
Meteorology and Atomic Energy 1968, Slade, D. A. (ed.).
Publication No. TID-24190f U.S. Atomic Energy Commission
Technical Information Center, Oak Ridge, Tennessee, July
1968. p. 445.
34. Compilation of Air Pollutant Emission Factors. Office
of Air Programs Publication No. AP-42, U.S. Environmental
Protection Agency. Research Triangle Park, North Carolina,
February 1972.
35. Blackwood, T. R., and R. A. Wachter. Source Assessment:
Coal Storage Piles. Contract 68-02-1874, U.S. Environmental
Protection Agency, Research Triangle Park, North
Carolina. (Final document submitted to the EPA by Monsanto
Research Corporation, October 1975.) 109 pp.
31
-------
APPENDIX A
LITERATURE SURVEY
A study was made to predict and analyze the parameters that
affect dust emissions from the six handling operations in crush-
ed stone processing:
• Drilling and blasting operations
• Transport operations
• Conveying operations
• Unloading operations
• Loading operations
• Crushing/grinding/sizing operations
Parameters analyzed fell into two major classifications: those
dependent on the material, and those dependent on the operation.
As could be expected, parameters dependent on the operation
are as varied as the operations themselves. Material-dependent
parameters, however, are generally the same for all operations.
These are moisture content, density, and "dustiness index,"
which will be defined as the mass of respirable dust adhering
to one pound of material.
The "dustiness index" is used to .determine differences in emis-
sions from, different materials undergoing the same operation.
Density, on the other hand, delineates differences in particle
size distribution between different samples of the same material,
1. DRILLING AND BLASTING OPERATIONS
The following factors influence the dust emissions from drilling
operations:
(1) Number of bits
(2) Sharpness of the bits
(3) Speed of the bits
(4) Depth of bit penetration
(5) Experience of the machine operator
32
-------
The literature search did not yield any quantitative data or
indicate a relationship between the emission factor and the
aforementioned factors. A qualitative relationship might pos-
sibly resemble :
_
d (2) (4) (5)
where the numbers in parentheses represent functions of the
respective variables shown above.
Of all the unit operations, blasting has been studied least
from the point of view of dust emissions. The literature search
yielded a potential list of factors influencing emissions:
frequency of blasting; bulk moisture content of the rock; par-
ticle size distribution; type and amount of explosive; and hole
size.
Some studies have been conducted on the magnitude of gaseous
emissions of NOX and CO from blasting. Stoichiometric ratios
of ammonium nitrate-fuel oil (ANFO) mixtures (94.5% to 5.5%)
should result in no emissions of NOX and CO. Theoretically,
more fuel oil results in no NOX and more CO than C02 , and less
fuel oil results in no CO and more NOx than N2 . Experimental
investigations by the Bureau of Mines (17) show that 4% fuel
oil results in 1.3 m3 (at standard conditions) of NOX per kg
of ANFO (0.10 std ft3 of NOX per lb of ANFO) and 1 . 3 m3 of
CO per kg of ANFO (0.10 std ft3 of CO per lb of ANFO) , while
6% fuel oil results in 0.32 m3 of NOX per kg of ANFO (0.025
std ft3 of NOx per lb of 'ANFO) and 1.8 m3 of CO per kg of ANFO
(0.14 std ft3 of CO per lb of ANFO) . The maximum emission
factor figures have been used for the severities calculated in
Appendix E.
2. TRANSPORT OPERATIONS
Transport operations have been discussed in detail in a separate
document (18) .
(17) Chaiken, R. F. Ammonium Nitrate-Fuel Oil Mixtures. In:
Toxic Fumes from Explosives. Publication No. PB 233 496,
'Bureau of Mines, Washington, D.C., May 1974. 24 pp.
(18) Blackwood, T. R., and P. K. Chalekode. Source Assessment
Document: Transport of Sand and Gravel. Contract
68-02-1320, U.S. Environmental Protection Agency, Research
Triangle Park, North Carolina. (Preliminary document
submitted to the EPA by Monsanto Research Corporation,
December 1974.) 87 pp.
33
-------
'3. CONVEYING OPERATIONS
Dust emissions from conveying operations come from windblown dust
during open conveying and conveyor discharge.
Emissions from conveyor discharge and parameters affecting these
emissions were evaluated by Cheng (19) . The material tested
was freshly mined coal, cut during a dry operation and placed in
plastic bags to maintain its natural surface moisture of about
0.8% as measured by a Soiltest Speedy Moisture Tester. Cheng
found the following relationship:
• 16
= 8'50
where R = specific formation of airborne respirable dust, g
A1 = cross-sectional area of th'e falling granules, cm2
p = material density of the coal, g/cm3
O . ,_.
g = gravitational acceleration = 980 cm/s2
H = height of fall, cm
m' = belt load, g/cm2
b = width' of the conveyor belt, cm • .
U, = linear speed of the conveyor belt, cm/s
Cheng concluded the following:
• About 10% of the adhering respirable dust becomes
airborne by the impact of dropping.
• Reduction of the height of material fall reduces the
formation of airborne respirable dust.
• For heavy belt loads (bed thickness » mean lump size) ,
an increase in the thickness of the coal bed reduces
the specific formation of airborne respirable dust.
4. UNLOADING OPERATIONS
Emissions from unloading operations result from dropping mate-
rials from conveying machinery onto storage piles. A Midwest
(19) Cheng, Lung. Formation of Airborne-Respirable Dust at Belt
Conveyor Transfer Points. American Industrial Association
Journal, 34:540-546, December 1973.
34
-------
Research Institute study (20) found an emission factor, Eu, for
unloading operations, based on kilograms of suspended dust
particles less than 30 ym in diameter per metric ton of aggregate
unloaded, to be represented by the relationship:
E = 0-02 kg of particulate (A-3)
u metric ton of aggregate
This emission factor was based on high volume sampling at a sand
and gravel plant in the Cincinnati area. The emission factor,
Eu, was believed to be dependent on the surface moisture of the
material, estimated by the Precipitation-Evaporation (P-E) Index.
For an analysis of other factors affecting emissions from un-
loading operations, see Section 3 above, "Conveying Operations."
Although the relationships derived for emissions from conveyor
discharge are based on the conveying of coal, only a correction
factor for the relative dustiness of the material handled need
be applied to make the equation applicable to all conveying and
unloading operations.
5. LOADING OPERATIONS
Emissions from loading operations occur in the transfer of
material from storage to transporting vehicles. For aggregates,
this transfer is accomplished by power shovels that scoop ma-
terial from open storage piles and dump it into transporting
vehicles, usually trucks. Dust arises from the scooping and
the dropping processes.
Emissions from dropping are determined by many of the same
parameters that determine dust formation from conveyor discharge,
although there are definite dissimilarities in mode of discharge
between conveyor belts and power shovels. Dust emissions should
be determined by:
(1) Height of material fall
(2) Quantity of material dumped
(3) Density of material
(4) Rate at which material is dumped
(5) Moisture content of material
(6) "Dustiness index" of material
(20) Cowherd, Chatten. Development of Emission Factor for
Fugitive Dust Sources. Publication 1152, Midwest Research
Institute, Kansas City, Kansas. Presented at APCA meeting,
Denver, Colorado, June 1974. 175 pp.
35
-------
An equation determining the amount of respirable dust, R^, formed
by power shovel discharge, based on an equation for conveyor'
discharge, should be of the form:
_ (1) (3) (6) . ..
Rd a (2) (4) (5) (A 4)
Each number in parentheses in Equation A-4 represents a function
of its respective parameter, as listed above.
Dust emissions from scooping operations are more diffiqult to
define, since no information even remotely relevant was available.
However, the following factors are believed to be influential in
determining emissions from this source:
(7) Density of material
(8) Moisture content of material
(9) "Dustiness index" of material
(10) Degree of storage pile disturbance rendered by
the scooping machinery
Although there is no basis for determining a relationship between
these variables and respirable dust formation, Ra, a qualitative
relationship might .possibly resemble:
(7) (9) (10) •
Rd a (A
where each number in parentheses represents a function of the
respective variable shown above.
Although not applicable to the determination of the respirable
dust formation (R^) , a Midwest Research Institute study (20)
found an emission factor, EI , expressed as kilograms of dust
less than 30 urn in diameter emitted per metric ton of material
loaded, for loading crushed limestone at an asphalt plant in
Kansas City to be:
EI = 0.025 kg of dust/metric ton of material loaded (A-6)
The emission factor, EI, was believed to vary inversely with the
square of the P-E Index of the area considered.
6. CRUSHING/GRINDING/SIZING OPERATIONS
Emissions from crushing, grinding, and sizing operations result,
from respirable dust formed during size reduction and crusher or
screen discharge.
36
-------
The factors affecting discharge emissions are the same as those
for conveyor and power shovel discharge (see Section 3, "Conveying
Operations," and Section 5, "Loading Operations," above).
Dust emissions from size reduction are judged to be influenced
by:
(1) "Dustiness index" of material
(2) Moisture content of material
(3) Degree of particle-size reduction
(4) Rate of material flow through size reducer
A qualitative expression for respirable dust formation, R-, , is
believed to be :
R a fA-7)
Rd a (2) (4) (A 7)
where each number in parentheses is some function of the respec-
tive parameter listed above.
If atmospheric dispersion of the respirable dust formed is to
occur, an induced airflow (Q) must be present. For most crushers,
which operate at a relatively low speed, airflow is induced only
during discharge. (See Section 3 in this Appendix for a quanti-
tative evaluation of airflow induced by discharge.)
High speed pulverizers create airflow during size reduction as
well as discharge. Airflow induced by high speed size. reduction
has- been found to be inversely proportional to the rate of
material flow through the size reducer (21) .
(21) Andresen, W. V. Industrial Hygiene Design in Raw Materials
Handling Systems. American Industrial Hygiene Association
Journal, 23(6):509-513, November-December 1962.
37
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APPENDIX B
SAMPLING EQUIPMENT, PROCEDURES, AND ANALYSIS
Since analytical expressions for emission rates could not be
derived, two types of monitors were used to sample the air pol-
lution emissions from crushed stone operations. High volume
samplers were used to sample the quarrying activities. A portable
dust monitor was used to sample the various unit operations of
the processing'plant. This appendix describes the high volume
sampling methods and equipment used, the portable dust monitoring
apparatus and procedure employed,- and -the equipment and methods
used to analyze the emissions that were sampled.
1. HIGH VOLUME SAMPLING METHODS AND EQUIPMENT
High volume samplers3 were positioned around the quarrying source
as shown in Figure B-l. .Some rules used for positioning the high
volume samplers are listed in Table B-l and additional guidelines
used for such sampling are, presented in Table B-2. Figure B-2
gives the flow chart for determination of atmospheric stability
class (22). The positions of samplers So/ Si, Sz, 83, and Sit
are recorded on the form shown in Figure B-3. Atmospheric sta-
bility and barometric pressure are also recorded on this form.
Quarrying samples were taken on a day when there were no process-
ing activities to create background interference. High volume
samplers were used because the quarrying operations were located
in a pit where emissions were not readily entrained in the wind.
In addition, the quarrying operation is an area source of pollu-
tants. Thus on-the-spot measurement of point sources was not
possible.
aGeneral Metal Works, Inc., Cleveland, Ohio.
(22) Blackwood, T. R., T. F. Boyle, T. L. Peltier, E. C. Eimutis,
and D. L. Zanders. Fugitive Dust from Mining Operations.
Contract 68-02-1320, Task 6, U.S. Environmental Protection
Agency, Research Triangle Park, North Carolina, May 1975.
p. 34.
38
-------
WIND AZIMUTH
METEOROLOGICAL STATION
Figure B-l.
High volume sampling arrangement of high volume
samplers labeled S0, Slr S2, S3, and S^.
39
-------
TABLE B-l. PLACEMENT OF SAMPLES DOWNWIND OF OBSTRUCTIONS
1. Both the open source height and the obstructions must meet
the required minimum distance criteria.
2. Stability class is determined from cloud cover, wind speed,
and time of day (see Figure B-2).
3. The height of obstruction or source equals H.
Stability Minimum distance downwind
class from obstruction peak
A 5H
B 7H
C 10H
D 17H
E , , 25Ha
Other classes Cannot be done
aRequires an additional sampler at least 15H downwind for backup,
TABLE B-2. OPEN SOURCES SAMPLING GUIDELINES
1. Determine predicted wind direction and speed from:
a. U.S. Weather Bureau and/or
b. Field estimate
2. Determine atmospheric stability class expected - see table
on worksheet (Figure B-2).
3. Locate positions of samplers around source. Use guidelines
for downwind distance (Table B-l).
4. Place upwind sampler (background) and start sampling.
5. Place wind instrument and downwind samplers for source
monitoring.
6. Monitor wind direction and speed every 15 minutes and sta-
bility class every 2-3 hours; note time sampler f-low rates
were checked at first 1/2 hour and then every 1-1/2 hours.
If wind direction is off centerline by more than 0.78 rad •
(45°) in two consecutive readings, stop samplers until
direction returns within 0.78 rad (45°) for 15 minutes.
7. Complete sampling in minimum sampling time determined by
project leader.
40
-------
START
ATMOSPHERIC
CLASS ISO
RADIATION INDEX = -2
RADIATION INDEX =
-1
TIME OF DAY
INSOLATION
CLASS
NOONTIME ,
LATE AM. EARLY PM
Ml DAM, MIDPM
EARLY AM. LATE PM
4
3
2
1
o
WIND
SPEED
CALM
(0 - 2'mph)
LIGHT
(2 - 5 mph)
MODERATE
(5 - 10 mph)
STRONG
( > 10 mph)
NET RADIATION INDEX
4
A
A
B
C
.?
A
B
B
C
2
B
C
C
D
I
C
D
D
D
tt
D
D
D
D
:1
f
i
D
D
-2
F
F
E
D
STABILITY CATEGORIES
Figure B-2. Flow chart of atmospheric stability class determination (22).
-------
sampler.
centerline
actual
dry biilb
wet bulb
Run No .
DATE
barometric
pressure
op
op
"He
Op
Op
ATMOSPHERIC STABILITY DETERMINATION
reference
line
A
B
C
D
E
F
G
ft. (measured)
ft. "
ft. "
ft. "
ft.
ft. (estimated)
ft. "
TIME
STABILITY
COMMENTS:
Sampler
S
Filter No.
Brinks sampler located next to S
wind instrument is behind' S_
obtain sample of source before signing sheet
Sampling
crew
Figure B-3. Fugitive dust sampling worksheet,
42
-------
The arrangement in Figure B-l permitted correlation with horizontal
dispersion, and sampler 83 illustrated downwind power law decay.
For this arrangement, the origin was defined as the source with
all remaining points in the usual Cartesian coordinate system.
The angle of mean wind direction was §. The downwind distance,
Xi, of any point Si to the wind direction centerline was computed
in the following manner:
IV = tan 6 (.B-l)
and for point Si with Cartesian coordinates x., y. (e.g.;
for point Si*, x.^ = D, y.^ = C)
Yi
nt2 = ~— (B—2)
i
the angle a was found from:
mi - mz
" arctan
the lateral distance Y. is:
mi
Yt = (sin a) /XA* + y^ (B-4)
and the downwind distance X. is:
XL = (cos a) /x^ + yiz - (B-5)
The sampling time for high volume samplers was about 45 minutes
and five different samplers were used to monitor at So, Si, 82,
S3, and Sit.
Prior to sampling the high volume samplers were calibrated 'by
use of a calibrating orifiqe assembly and water manometer. (These
calibration units were adjusted with a positive displacement
meter.) A chart was then drawn of airflow versus static pressure.
After the orifice was attached to the unit, the airflow was var-
ied by the addition of perforated plates across the airflow
stream. A calibration curve was then plotted relating airflow
readings to actual flow in nonmetric units..
Prior to sampling, each filter was inspected for imperfections,
desiccated in a balance room, and weighed to the nearest milligram
in a weighing chamber. The tare weight was then recorded and
the filter holder labeled.
43
-------
Nuclepore® membrane filters were used for sample collection.
Their relatively low tare weight (500 rag) and high flow capacity
(0.036 m3/min-cm2 , 93.3 kPa pressure drop) 'in comparison with
similar filters enabled the particulate collected to comprise a
higher percentage of tare weight and thus provide results within
the measurable range. The high volume samplers collected particles
less than 100 um in size. Weights were determined to the nearest
milligram, .airflow rates to the nearest 0.005 m3/s, and time to
the nearest 5 minutes. • After particulate matter on the filters
was weighed (subtracting the tare weight) , the mass concentration
of suspended particulate was computed with the volume of air
sampled .
Volume was determined from the initial and final airflow readings.
These rotometer values were recorded on the form shown in Table
B-3 along with the wind speed and direction. (These readings
are converted to m3/min through an appropriate calibration curve.)
The volume of air sampled was then determined as follows:
(Q, + Qf) t
' V = — i - Of s (B-6)
3. 2.
where V = air volume sampled, m3
cl
Q. = initial airflow rate, m3/min
Qf .= final airflow rate, m3/min
t = sampling time, min
5
Once the volume was determined a'nd the final weight of the filters
established, the mass concentration of particulates was determined
by:
(Wf - Vl±) x 106
cl
(B-7)
where x = mass concentration .of particulate, yg/m3
W. = initial (tare) weight of filter, g
Wf = final weight of filter, g
V = volume of air- sampled, m3
a
106 = conversion of g to pg
The mass concentration of particulate' collected at reference
sampler So was first subtracted from the mass concentration of
the other samplers (Si, 82 / 83, and SO to yield the net partic-
ulate concentration due to the quarrying activities. Mass
concentrations are reported to the nearest yg/m3.
44
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Table B-3. FUGITIVE DUST SAMPLER AND METEOROLOGICAL DATA LOG
Date
Run
Page
Time
(24 hr
clock)
Totals
Average
Total el
Wind
Speed Direction
mph
avg.
range
Compass
degrees
avg.
range
apsed time
Si
Roto
cfm
Act
cfm
S2
Roto
cfm
Act
cfm
S3
Roto
cfm
Act
cfm
S4
Roto
cfm
Act
cfm
Other comments
Sampling crew
01
-------
Mass emission rate was then calculated as an average of the cal-
culations done for N sampler readings using Turner's equation
for a ground level source with no effective plume rise (23)
(Equation B-8):
, N Y . Tra a u
Q = i £ r y,,A -n (B-8)
1=1 exp
where Q = emission rate, g/s
X . = net ground level concentration at
(Xi, Y±, 0) , g/m3
a , a = standard deviation of plume concentration
distribution in the horizontal and vertical
planes,' respectively, m
u = arithmetic mean wind speed, m/s
IT = 3.14
Y. = lateral distance (Figure B-l)
X. = downwind distance from source along dispersion
centerline (Figure B-l)
The validity of applying this equation for determining emission
rates is discussed in section 4 of Appendix C.
A meteorological station was employed to monitor the wind speed
(u), direction, and temperature. Wind speeds were averaged
every minute with a mean recorded for each 15-minute interval.
The mean wind speed (u) was calculated from the average of the
15-minute recordings over the entire run. The wind direction
variation was less than ±0.785 rad (±45°) from the centerline
during the samplings. Continuous functions are used to calculate
the atmospheric stability class. These functions are listed
in Tables B-4 (24) and B-5 (25).
(23) Turner, D. B. Workbook of Atmospheric Dispersion Estimates,
1970 Revision. Public Health Service Publication No. 999-
AP-26, U.S. Department of Health, Education, and Welfare,
Cincinnati, Ohio, May 1970. 84 pp.
(24) Eimutis, E. C., and M. G. Konicek. Derivations of Continu-
ous Functions for the Lateral and Vertical Atmospheric
Dispersion Coefficients. Atmospheric Environment, 6:859-
863, March 1972.
(25) Martin,-D. 0., and J. A. Tikvart. A General Atmospheric
Diffusion Model for Estimating the Effects on Air Quality
of One or More Sources. Presented at the 61st Annual Meet-
ing of the Air Pollution Control Association, St. Paul,
Minnesota, June 23-27, 1968. 18 pp.
46
-------
TABLE B-4. CONTINUOUS FUNCTION FOR LATERAL ATMOSPHERIC
DIFFUSION COEFFICIENT a (24)
a = AX°-9031
Stability class
A
B
C
D
E
F
A
0.3658
0.2751
0.2089
0.1471
. 0.1046
0.0722
TABLE B-5. CONTINUOUS FUNCTION FOR VERTICAL ATMOSPHERIC
EC]
,B
DIFFUSION COEFFICIENT a (25)
£i
az = AT
Stability
Usable range class Coefficient
>1,000 m A 0.00024 2.094 -9.6
B 0.055 1.098 2.0
C 0.113 0.911 0.0
D 1.26 0.516 -13
E 6.73 0.305 -34
F 18.05 0.18 -48.6
A2 B2 C2
100 - 1,000 m A 0.0015 • 1.941 9.27
B 0.028 1.149 3.3
C 0.113 0.911 0.0
D 0.222 0.725 -1.7
E 0.211 0.678 -1.3
F 0.086 0.74 -0.35
A3 B3 C3
•D 3 -J
<100 m A 0.192 0.936 0
B 0.156 0.922 0
C 0.116 0.905 0
D 0.079 • .0.881 0
E 0.063 0.871 0
F 0.053 0.814 0
47
-------
2.
PORTABLE DUST MONITORING
A GCA Model RDM 101-4.respirable dust monitor^ was used to sample
the downwind concentration of particulates from the various unit
operations of the processing activity. This is an advanced instru-
ment for on-the-spot measurement of mass concentrations of respir-
able (<10 pro) particulates or total mass loading of particulates.
It is a portable and fully automated unit with direct digital
readout of the mass concentration of airborne particulates. Read-
ings of 4 minutes to 30 minutes can be taken, and a traverse of
points around a source of interest can be accomplished quickly.
Results are obtained by electronic measurement of the beta absorp-
tion of the collected sample. A cyclone collection system is used
as a first stage for removal of the >10-ym particulates.
During the GCA sampling, using the sampling apparatus shown in',
Figure B-4, all the data for each unit operation were recorded on
the form shown in Table B-6. For each concentration reading the
ANEMOMETER
WIND METER
WEATHER POLE
CLIPBOARD -^A CYCLONE SEPARATOR
RESPIRABLEDUST
MONITOR
SAMPLING PLATFORM
STOPWATCH
TRIPOD STAND
Figure B-4. Sampling apparatus,
GCA Corporation, Bedford, Massachusetts.
48
-------
TABLE B-6. FIELD DATA FORM
MODEL: POINT-1
LINE =2
SOURCE TYPE
DATE,
BY_
UNIT OPERATION
"WIND
SPEED
MPH
DIS"
X
FANG
Y
E, FT
TIME
MlN
READ.
mg/m3
CONG
/uqlw?
R/T
BCD
/"g/m3
A,
/«g/m3
Q,
g
s'
M
COMMENTS
TIME OF DAY
ATM. STABILITY
TOTAL SAMPLING TIME
4 MINUTES
8 MINUTES
16 MINUTES
20 MINUTES
30 MINUTES
37 MINUTES
MULTIPLY READING BY
1
0.46
0.23
0.184
0.122
0.1
-------
mean* wind speed was determined by averaging 15-second readings of
the wind meter. This meter was connected to an anemometer set
atop a 3.05-m (10-ft) pole. The downwind distance, X, was measured
by physically pacing the shortest length to the source. Periodi-
cally the time and atmospheric stability class (using Figure B-2)
were recorded on the bottom of the form. The terms listed on the
form are explained in Table B-7. Any factors that may have affect-
ed concentration or emission rates were mentioned in the column
labeled "Comments."
TABLE B-7. EXPLANATION OF FIELD DATA FORM TERMS
Term (units)
Meaning
Read (mg/m3)
Cone, (ug/m3)
R/T
BCD (ug/m3)
A (T-ig/m3)
Q (g or g/s)
S1
M
Digital readout of concentration
Converted concentration for sampling times
greater than 4 minutes (per list in lower
right hand corner of form)
R = respirable reading
T = total mass reading
Background concentration
The difference between the converted
concentration and the background
Calculated emission rate
Stability for the time and day the unit
operation was sampled
The model used and referenced as 1, 2, or 3
(point, line, or dose, respectively)
When this form was completed it was programmed into an APL system
computer and the emission rate, Q, was calculated in accordance
with the model specified in column "M." The dose model refers to
the concentration multiplied by the time of operation.
3.
ANALYSIS
The emissions from sampling were analyzed for free silica, fibers,
and trace elements. After the Nuclepore filter was weighed, one
portion was selected for microscopy examination and another for
composition analysis. X-ray fluorescence was chosen to give a
semiguantitative determination of particulate composition.
a. Principle of X-Ray Fluorescence (XRF) Analysis
XRF analysis is based on measuring individual, characteristic
x-rays for each element in a sample by energy dispersive tech-
niques. These secondary fluorescent x-rays are generated by
50
-------
irradiating the specimen with a primary source of x-rays using
either a tungsten or rhodium target x-ray tube. All secondary
x-rays are detected simultaneously with a silicon semiconductor
detector. By using suitable amplifiers and an x-ray energy
distribution analyzer, the characteristic x-rays for each element
are electronically separated based on their energy and are dis-
played in either a spectral or alpha-numeric mode via video
monitor. The data are also stored in a computer memory for
additional data improvement or for on-line computerized data
reduction and presentation in a teletype print-out.
An on-line computer is used for data reduction. Computer programs
enable manipulation of spectral data to eliminate interfering lines,
to integrate peaks, to subtract backgrounds, to correct for inter-
element and matrix effects, and to provide a variety of quantita-
tive conversion equations to reduce raw counts to elemental
concentration.
b. Applicability of XRF
The XRF technique is applicable to qualitative and quantitative
elemental analyses (sodium to uranium) for solids (whole sections
or powdered) and liquids (including solids in solution). In
the specific case" of particulate collected on filters, the direct
measurement of these specimens can provide a detection limit of
<0.2 ug/cm2 with sample loadings of 1.2 ug/cm2. The detection
limit is influenced by many factors including energy of the x-
rays being emitted by the elements, matrix, counting times,
excitation source, and sample chamber atmosphere. For particulate
on filter paper with a loading of 1.2 ug/cm2 and with a rhodium
excitation source, the following detection levels can be attained:
Detection level,
Element yg/cm2
P ' 0.20
S 0.11
K 0.15
Ca 0.06
Cr 0.06
Fe 0.05
Ni 0.05
Cu 0.05
. Zn 0.04
As 0.04
Br 0.07
Cd 0.13
Ba 0.13
Hg 0.08
Pb 0.07
51
-------
c. XRF Apparatus
The analytical system used in these measurements is composed of
an EDAX International, Inc. Mark II Basic EDAM System, an EDAX
Model 707A Super Analyzing Unit, a Data General Corp. 12 K
Computer (Nova 1220), and a Teletype 33TC. Either a rhodium or
1 tungsten target x-ray tube is available. The system can be op-
erated with the sample maintained in vacuum or in a helium
purged atmosphere. Samples up to 76 mm (3 in.) in diameter can
be analyzed.
d. Calibration of XRF Equipment
Quantitative'analysis with the x-ray technique is based on using
reference standards of known concentrations of the desired ele-
ments in a matrix similar to that of the unknown specimens, or
using mathematical corrections through computer programs to cor-
rect for inter-element and matrix effects.
If a range of standards is available, it is possible to establish
a working curve for each element which is a plot of concentra-
tions in micrograms (or .yg/cm2) vs. the intensity of the x-rays
characteristic of each element. If the range of standards is
not available, the ratio of the intensity of the peak of unknown
concentration of an element to the intensity of the peak of a
known concentration of that same element will provide a reliable
semiquantitative analysis (± 50% or less of the amount present).
Standards are prepared by precipitation or deposition of NBS
Standard Research Materials, metal oxides or salts, or portions
of "loose" particulate collected during long-term sampling. In
the latter case, emission spectrographic analysis of this mater-
ial serves to provide the needed compositional information for
preparing standards. Several deposition procedures are used for
preparing semiquantitative standards including the filtration
of particulate suspended in carbon tetrachloride and the filtra-
tion of particulate suspended in gas matrix or deposited from
solution.
Other semiquantitative measurements of particulate collected
on filters are made by correlatng the x-ray fluorescence respons-
es of test samples with emission spectrographic analyses of ash
for one or more of the test specimens in a set. This correla-
tion serves to provide a semiquantitative means of rapidly ana-
lyzing large numbers of filters by XRF without going through an
ashing step, which is required for emission spectrographic
analyses of filters with low loadings.
e. Procedure for XRF Analysis
Based on the type of sample matrix and the elements being measur-
ed, the excitation source and the x-ray excitation voltage are
selected. Either a helium flush or vacuum is applied to the
52
-------
sample chamber, and proper selection of the energy range is made
to optimize response. The filter specimen is analyzed by counting
the secondary x-rays for 100 seconds to 2,000 seconds, depending
on quantity of material on the filter.
The spectral data are manipulated by computer software to smooth
the statistical channel-to-channel fluctuations in the spectrum,
subtract background or spectra characteristic of residual trace
elements in the filter, strip a series of peaks characteristic of
specific elements, and obtain quantitative or semiquantitatiye
data by comparing the spectral intensity of the test specimen with
the known values of the standard samples.
The computer provides the resulting values (quantitative or semi-
quantitative) in yg/cm2 or comparable notation as programmed.
f. Quantitative Determination of Free Silica as .Quartz
The permissible concentration for respirable silica-containing
dusts is computed based on measuring the quartz content and using
the formula (26) .
permissible dust (mg/m3) = % quartz + 2 (B~9)
The percent crystalline quartz is determined on a respirable-
size fraction of the dust. At present, there is no one acceptable
method for the quantitative determination of quartz in air samples,
but there are five general methods which can be applied to the
quantitative analysis o'f filter samples for quartz: x-ray dif-
fraction; differential thermal analysis; colorimetry; optical
microscopy and petrography; and infrared spectrophotometry. In
addition, there are several variations for each method. The tech-
niques and potential limitations are reviewed in a number of
articles, including those by Larsen et al. (27) and Freedman et
al. (28).
(26) Aerosol Technology Committee. Guide for Respirable Mass
• Sampling. American Industrial Hygiene Association Journal,
31:133, January-February 1970.
(27) Larsen, D. M., L. J. Von Doenhoff, and J. V. arable.
The Quantitative Determination of Quartz in Coal Dust
by Infrared Spectroscopy. American Industrial Hygiene
Association Journal, 33:367-372, June 1972.
(28) Freedman, R. W., S. Z. Toma, and H. W. Lang. On-Filter
Analysis of Quartz in Respirable Coal Dust by Infrared
Absorption and X-Ray Diffraction. American Industrial
Hygiene Association Journal, 35:411-418, July 1974.
53
-------
Wet chemical procedures such as the Talvitie Method employing
phosphoric acid, differential thermal analysis, optical
microscopy, and petrographic analysis are inaccurate, insensitive,
and time consuming (29, 30).
Infrared spectrophotometry and x-ray diffraction appear to
be the best techniques available (23, 31). The x-ray diffraction
technique for determining quartz is adversely affected by
interfering crystalline material (e.g., muscovite, potash
feldspar (microcline), plagioclase, mica (biotite), sillimanite,
graphite, and aragonite) and by x-ray background scatter
from filters.
Little interference is encountered when using infrared spec-
trophotometric techniques. (In these techniques, the only
spectral interference in the analytical region, 850 cm"7 to
750 cm~7, occurs if sample ashing of kaolins-containing specimens
is performed at temperatures in excess of 600°C.)
The infrared spectrophotometric approach was chosen for this
study. Although several procedures can be adapted to these
types of specimens, the method developed by Cares et al. (32)
was used for determining quartz in airborne respirable granite
dust. The method involves ashing of the filter and sample •
at 550°C and mixing and pressing the sample ash with KBr to
form a solid pellet which is placed in an infrared spectrophoto-
meter for spectral analysis. The detailed analytical procedure
is as follows:
(29) Durken, T. M. Determination of Free Silica in Industrial
Dust. Journal of Industrial Hygiene and Toxicology, 28:
217, February 1946.
(30) Edwards, G. H. Comparison of X-Ray Diffraction, Chemical
(Phosphoric Acid), and Dispersion Staining Methods for
the Determination of Quartz. American Industrial Hygiene
Association Journal, 26:532, September-October 1965.
(31) Freedman, R. w. Recent Advances in the Analysis of
Respirable Coal Dust for Free Silica, Trace Elements, and
Organic Constituents. Annals of the New York Academy of
Sciences, 200:7-16, December 1972.
(32) Cares, J. W., A. S. Goldin, J. J. Lynch, and W. A. Burgess,
The Determination of Quartz in Airborne Respirable
Granite Dust by Infrared Spectrophotometry. American
Industrial Hygiene Association Journal, • 34:298-305, July
1973.
54
-------
1. Collect the sample in the field with a size selective
sampler equipped with a low ash polyvinyl chloride membrane
filter which has excellent moisture stability (Mine Safety
Appliances Co. Membrane Filter, Part No. 62513 or equiva-
lent.) (The infrared spectrum of the ash from the MSA
filter does not interfere with the quartz determination.)
2. Place the filters in porcelain evaporating dishes (Coors
.4/0) and transfer them to a muffle furnace.
3. Heat to 550°C and maintain until the carbon is destroyed
(about 1-1/2 to 2 hours).
4. Remove the dishes carefully, cover, and cool.
5. Add 40 ± 5 mg of infrared-quality KBr (Harshaw Chemical
Co., Cleveland, Ohio) previously ground to minus 200 mesh
and kept in an oven at 110°C. (If sample weight is exces-
sive, a larger amount of accurately weighed KBr should
be added, and aliquots taken for final sample.)
6. Mull the sample ash and KBr with a small Alundum pestle
until they are thoroughly mixed. Take care not to apply
pressure or grind, which may alter the spectrum.
7. With a spatula, transfer the mixture as completely as
possible to a pellet press equipped with a 6.4-cm (1/4-
in.) diameter punch and die.
8. Tap lightly to distribute the powder evenly, center the
punch carefully, and press. Release the pressure, turn
the die about 3.14 rad (180°), and repeat the pressing.
With good technique a clear pellet without cracks or opaque
spots will be obtained.
9. Transfer the pellet ,to a pellet holder and place the mounted
pellet in the sample beam of an infrared spectrophotometer
(Perkin-Elmer. Model 421 Grating Spectrophotometer or equiv-
alent) .
10. At a wavelength of about 11.8 ym and wide slit, adjust
the base line to a maximum transmission (or minimum absor-
bance) and scan to 13 urn. For identification purposes
it may be necessary to observe the 14-ym quartz band.
Reverse.the sample for a repeat scan.
11. To obtain the weight of quartz in the sample, subtract
the absorbance of the base line at 12 ym from that at
12.5 ym and compare the net absorbance with a calibration
curve obtained from a series of quartz-KBr standards.
Absorbances should be below 0.5 for satisfactory linearity.
Samples of greater absorbance are brought into this range
55
-------
by breaking up the pellet, diluting it with KBr, and aliquoting
if necessary. Assuming 100% sample recovery with a minimum.
possible measurement of absorbance of 0.02, the detection limit
is approximately 5 yg of quartz in a sample.
Preparation of calibration standards is done as follows:
1. Prepare quartz standards from 5-ym grade Minusil R, a
high-purity crystalline silica obtainable in several size
ranges from the Pennsylvania Glass Sand Corp., Pittsburgh.
Ninety-eight percent of the particles of this grade are
less than 5 ym in diameter.
2. Place the standards in a muffle furnace, and heat them
to the same temperature as the samples before use.
3. Prepare stock standards by blending carefully weighed
amounts of Minusil and R-grade KBr either by mulling with
an Alundum mortar and pestle or by use of a commercial
type of mixer such as the "Wig-L-Bug."
4. Dilute the stock mixture in the same manner to obtain
concentrations which will yield 40 mg of pellets containing
from 5 yg to 150 yg of quartz.
5. Press pellets and record spectra in the same manner as
with the samples.
6. Plot calibration curve of net absorbance versus weight
of quartz.
g. Quantitative Determination of Fiber
A fiber count was done for the samples collected on the high-
volume filters. The sample preparation and counting procedures
are given below:
(1) Sample Preparation—
The counting medium consists of 50 mg of membrane filter dis-
solved per 50 ml of a solution of one to one (vol.) dimethyl
phthalate and diethyl oxylate. Fibers are counted on wedge
shaped sections cut from the filter and mounted on a clean
25 mm x 75 mm glass microscope slide. A drop of counting medium
is placed on the slide, dust side up. The wedge is then covered
by a No. 1 1/2 cover slip. Care is taken to avoid trapping
air. Counting of fibers is started after 30 minutes and com-
pleted within 2 days to avoid fiber migration and crystal growth,
A microscope equipped with phase-contrast capabilities, a 4-
mm "high dry" phase-contrast objective (40X to 45X), and a
10X eyepiece are used to count the sample.
56
-------
(2) Counting--
A fiber is defined as a particle 5 urn long with length three
times the diameter. One side of the wedge is arbitrarily chosen
as the 'counting1 side. Fibers entering the area from either
of the other two sides are not counted. Touching fibers (fibers
with one end touching another fiber regardless of the resulting
angle) are considered as one. Fibers crossing each other are
counted individually. A minimum of 20 fields are counted.
Counting is terminated after 100 fields have been searched.
(3) Calculations—
The concentration of fibers is calculated as:
where Xfibers
fibers
fields
R1
fibers *,R'
^fibers ~ fields • V
= concentration of fibers per ml of air
= total number of fibers counted
= total number of fields counted
= filtration area divided by area of a
counting field
V = sample volume of air, ml
(B-10)
57
-------
APPENDIX C
SAMPLING RESULTS AND ERROR ANALYSIS
The purpose of sampling is to obtain an estimate of the overall
plant emissions and also the relative contributions of the
various unit operations. This appendix describes the sites that
were selected for sampling, the results of the sampling effort,
the emission factors determined, and an estimate of the error
associated with the emission rate data.
Two crushed traprock facilities were chosen whose operations are
representative of the crushed stone industry. Traprock accounts
for 68% of total crushed stone production. Further, these plants
were located in areas with meteorological conditions favorable
for sampling.
1. SITE DESCRIPTION
a. Plant A
(1) Blasting, and Drilling—
At the. blasting site, holes are drilled in the rock in a square
pattern, with water applied at the drill face. These holes are
the'n charged with ANFO (ammonium nitrate and fuel oil) and dyna-
mite, and the rock is blasted away.
(2) Quarrying—
A shovel and front-end loader dump blasted material onto haul
trucks. The front-end loader is also used to reposition material
that facilitated use of the shovel. Three trucks are used to
haul the rock on an unpaved road to a hopper.
(3) Primary Crushing and Unloading—
Material is fed by gravity from the hopper into the primary
crusher. This unit fragments the rock down to a top size of
150 mm to 180 mm (6 in. to 7 in.) in diameter. Crushed material
is transferred via belt conveyor to a storage pile.
(4) Processing Activities—
The process begins with material conveyed from the stockpile
generated by the primary crusher. This aggregate has a top size
of 0.25 m (10 in.) and is transferred by tunnel belt conveyor to
the first screen tower. Undersize material at the tower is
gravity loaded into a bin that is periodically gravity unloaded
58
-------
onto trucks. Oversize stone is either chute fed into a 2.1-m
(7-ft) cone crusher which breaks the aggregate down to a top
size of 0.1 m (3 to 4 in.)., or belt conveyed by a stacker to" a
surge pile. Material from this pile is belt conveyed to the
next screen tower where undersize material falls into the bin
for unloading, and oversize material is crushed by a 1.7-m
(5 1/2-ft) crusher to a top size of'44 mm (1 3/4 in.) and belt
conveyed to a third screen tower. At this tower, undersize
material is also bin fed to trucks. Oversize stone is crushed
to a top size of 16 mm (5/8 in.) and belt conveyed to the con-
veyor feeding the screen for resizing.
Trucks loading at the screen stations are positioned under the
bins and the bottom gates are opened,, letting stone fall by
gravity into the trucks. The stone is then transported on un-
paved roads to the appropriate stockpile. Front-end loaders
work in the .area, smoothing the tops of the stockpiles and fil-
ling customer trucks that enter. These vehicles all travel on
unpaved roads. A tank truck also circulates throughout this
facility, spraying water on the roads for dust suppression.
The plant operates for about 4.5 hr/day, 2 days/wk. The pro-
cessing rate through the primary crusher is about 545 metric
tons/hour.
The sampling data and results are given in Table C-l.
b. Plant B
The blasting, quarrying, and primary crushing activities are
similar to those at Plant A; hence, only the processing activi-
ties are described.
At the processing plant, material from the stockpile generated
by the primary crusher is fed by belt conveyor to a scalper
screen. This unit feeds the oversize material to a 1.67-m
(5 1/2-ft) secondary crusher. The crushed material and the
undersize have a top size of 82 mm (3 to 3 1/2 in.). This
aggregate is then fed by belt conveyor to another screen.
Undersize passing through the screen falls into a hopper that is
unloaded whenever trucks are positioned underneath, or it is
belt conveyed to a surge pile. Oversize material is gravity
chute fed into two crushers, 0.91-m (3-ft) and 1.22-m (4-ft)
shortheads, connected in series. The use of both units is
dependent on the size of aggregate being run.
Crushed material, 38 mm to 44 mm (1 1/2 in. to 1 3/4 in.), is
transferred from here by belt conveyor to two screens. Under-
size stone falls by gravity into two hoppers and is loaded onto
trucks periodically. Oversize material is loaded by gravity
chute into a crusher, a 1.22-m (4-ft) shorthead, from which the
crushed material is conveyor fed back to the conveyor originally
59
-------
TABLE C-l. PRODUCTION OF CRUSHED STONE - PLANT A
UNIT OPEPATION
U
Z TIME - CFI
Q
UNITS
QUARRYING
QUARRYING
PRMRY CRUSHER + UNLO
SCNDRY CRUSHER + SCR
SCNDRY CRUSHER + SCR
SCNDRY CRUSHER + SCR
FINES CRUSHER + SCRF
CONVEYING
CONVEYING
UNLOADING TRUCK
UNLOADING TRUCK
UT7LOADING TRUCK
UNLOADING TRUCK
LOADING TRUCK
LOADING TRUCK
17.
1-7.
17.
8.
8.
8.
8.
2.
2.
8.
8.
8.
8
8.
17.
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
615.
791.
100.
123.
123.
123.
123.
110.
110.
210.
70.
70.
210.
123.
40.
X, Y,
chi =
0
0
0
0
0
0
-0
0
0
0
0
0
0
0
0
U =
Z =
Q =
S ' =
X =
Time =
0.0 30.0 45.0
0.0 0.045.0
0.0 0.012.0
0.0 0.0 4.0
0.0 0.0 8.0
0.0 0.0 .4.0
0.0 0.0 4.0
0.0 20.0 4.0
0.0 20.0 4. 0
0.0 0.0 4.0
0.0 0.0 4.0
0.0 0.04.0
0 . 0 0.0 4.0
0.0 0.0 4.0
0.0 0.08.0
mean wind speed,
169.0
135.0
648. 0
554.0
221.0
280.0
114.0
40.0
614.0
10.0
80. 0
204.0
4.0
74.0
28.0
mph
dispersion coordinates
emission rate in
stability class
concentration at
units
X, Y,
1
1
1
1
4
5
2
1
2
5
5
1
2
3
1
.6027TO
. 595770
. 80877"
. 05777"
.218F"
. 314. 14.77"
.17677"
.70977"
.62477"
.02177
.51177"
.40577"
.008£~
.390770
.490F"
1
1
2
2
2
2
1
3
3
2
3
3
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G)
(G/SEC)
C
C
C
C
C
C
C
C
C
C.
C
C
C
C
C
(Figure B-l)
shown
Z
sampling time, min
-------
feeding the screens. All undersize material not guided into the
hopper is transferred by belt conveyor to a surge pile. The
aggregate top size at this point is 32 mm (1 1/4 in.). Material
from the surge pile Is conveyed by belt conveyor in a tunnel to
a screen, then separated into four sizes: 32 mm, 19 mm, 13 mm
or 5 mm (1 1/4 in., 3/4 in., 1/2 in., or 3/16 in.). Any oversize
stone is fed by gravity to a gyradisc. This crushed material is'
then belt conveyed onto the belt originally feeding the screens
for sizing. Undersize material is gravity loaded into a hopper.
Trucks then pull under the hopper for loading, then transfer the
material on unpaved roads to the appropriate stockpiles. All
trucks traveling from the load-out stations, and customer trucks
that have been weighed, travel on unpaved roads to the stockpile
areas. Empty trucks drive onto the stockpile and are filled by
a front-end loader. The front-end loader travels on unpaved
roads throughout the storage area either loading trucks or
smoothing out the tops of stockpiles. Loaded customer trucks and
trucks to be loaded leave the stockpile area and travel to their
respective destinations on unpaved roads. Tank trucks spray
water on the ground continuously to suppress dust formation.
The plant operates for about 6 hr/day, 5 days/wk. The processing
rate through the primary crusher is about 645 metric tons/hr. The
remaining crushers operate for about 9.5-hr/day at 2 days/wk.
The sampling data and results from the computer (in accordance
with input of Figure B-4) are given in Table C-2.
2. EMISSION FACTORS
The emission factors for respirable and total particulate emis-
sions were summarized earlier in TaJDle 3 (Section IV). The
emission factors were .derived using the results of sampling, as:
Emission factor = (Emission rate)f(Production rate)
a. Blasting
The amount of rock blasted was 19,970 metric tons (21,963 tons).
At average emission doses of 180 g of respirable particulates
and 1,070 g of total particulates, the emission factors for
respirable and total particulates are 0.0088 and 0.0522 g/metric
ton, respectively.
b. Drilling
The emission factor for drilling was determined by 'using the
sampling data from crushed granite operations, a separate study
under contract 68-02-1874. Four readings of ground level con-
centration were obtained at a wind speed of 0.9 meter/second
under D atmospheric stability conditions, 27 meters from the
61
-------
TABLE C-2. PRODUCTION OF CRUSHED STONE - PLANT B
UNIT OPERATION
U
Z TIME
CHI
Q
UNITS
cr>
ro
BLASTING
BLASTING
SCNDPY CRUSHER + SCR
SCNDRY CRUSHER +• SCR
SCNDRY CRUSHER + SCR
SCNDRY CRUSHER + SCR
TERTIARY CRUSHER + S
TERTIARY CRUSHER + S
FINES CRUSHER + SCRE
FINES CRUSHER + SCRE
UNLOADING TRUCK
UNLOADING TRUCK
UNLOADING TRUCK
UNLOADING TRUCK
UNLOADING TRUCK
UNLOADING TRUCK
UNLOADING TRUCK
UNLOADING TRUCK
UNLOADING TRUCK
LOADING TRUCK
LOADING TRUCK
8
8
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
.0
.0
• .3'
. 3
.3
,3
.3
.3
.3
.3
.3
. 3
.3
. 3
.3
.3
. 3
. 3
.3
. 3
. 3
204.
,,,'2'04.
." 70.
70.
70.
70.
123.
123.
130.
130.
123.
70.
90.
100.
90.
70.
90.
100.
90.
90.
90.
X, Y,
chi =
0
p
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
U =
Z =
Q =
S1 =
X =
Time =
0.0 0..0 16.0
P.P 0/0 55,0
0.0 10.0 4.0
0.0 10.0 12.0
0,0 10.0 4.0
0.0 10.0 12.0
0.0 0.0 4.0
0.0 0.0 4.0
0.0 0.0 4.0
0.0 0.0 4.0
0.0 0.0 4.0
0.0 0.0 4.0
0.0 0.0 4.0
0.0 0.0 8.0
0.0 0.0 4.0
0.0 0.0 4.0
0.0 0.0 4.0
0.0 0.0 8.0
0.0 0.0 4.0
0.0 0.0 4.0
0.0 0.04.0
mean wind speed,
393.0
678.0
742. 0
418.0
5'9 0 . 0
198.0
50. 0
272.0
27. 0
10.0
140. 0
10.0
25 . 0
28. 0
20. 0
22.0
672. 0
27. 0
72. 0
222 . 0
PO.O
mph
dispersion coordinates
emission rate in
stability class
concnetration at
units
X, Y,
1.
1.'
1.
6.
9.
3.
1.
6.
7.
2.
8.
2.
8.
2.
6.
4.
2.
2.
2.
7.
2.
798272
0 6 6ff 3
2427?"
99577
87427"
31427"
19127"
47927"
1 1 527~
63527"
003270
04327"
08127"
194270
465F"
49527
172271
116270
327270
1762^0
586270
1
2
2
2
2
2
3
3
1
1
1
1
(G)
(G)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G/SEC)
(G)
" (G)
(G)
(G)
(G)
(G)
(G)
(G)
(G)
(G)
(G)
C
C
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
B
(Figure B-l)
shown
Z
sampling time, min
-------
source. The concentration, 6.7 meters from the centerline was
70, 130, and 130 micrograms per cubic meter and 560 micrograms
per cubic meter on the plume centerline. The calculated emission
rates were 11.59, 21.52, 21.52 and 67.28 milligrams per second,
respectively. The average emission rate from wet drilling in
such operations is 0.015 g/s. At an average rate of 2 hr/hole,
30 holes/blast, and 19,970 metric tons/blast, the emission factor
for total particulates is 0.158 g/metric ton. It is assumed
(based on sampling at granite operations) that 10% of the partic-
ulate is respirable, yielding an emission factor of 0.0158
g/metric ton.
c. Quarrying
The average emission rate for total particulates is 1.60 g/s.
At a production rate of 533 metric tons/hr (586 tons/hr) , the
emission factor is 10.5 g/metric ton. It is .assumed (based on
sampling at crushed granite operations) that 10% of the particu-
late is respirable, resulting in an emission factor of 1.05
g/metric ton.
<3. Primary Crushing and Unloading
The emission rate for respirable particulates is 0.178 g/s. The
crushing and unloading operations occurred for 12 minutes, thus
yielding a dose of 128 g of respirable particulates. Three
32-metric ton (35-ton) trucks were unloaded into the crusher
during this 12-minute interval. The emission factor is thus
1.34 g/metric ton.
e. Secondary Crushing and Screening
At Plants A and B two average respirable emission rates of 0.048
g/s and 0.066 g/s at production rates of 533 metric tons/hr and
631 metric tons/hr (694 tons/hr), respectively, resulted in a
mean emission factor of 0.342 g/metric ton. The 95% confidence
limits are ±0.324 g/metric ton. Two total emission rates for
Plants A and B, of 0.1057 g/s and 0.097 g/s, respectively, pro-
duced a mean emission factor of 0.62 g/metric ton ± 0.997 g/metric
ton at the 95% confidence level.
f. Tertiary Crushing and Screening
At Plant B's production rate of 631 metric tons/hr, the respi-
rable particulate emission rate is 0.0119 g/s. The emission
factor is thus 0.0665 g/metric ton. The total particulate
emission rate is 0.0648 g/s (at Plant B) with an emission factor
of 0.362 g/metric ton.
63
-------
g. Fines Crushing and Screening
Two total emission rates, 0.0218 g/s and 0.00712 g/s, were cal-
culated at Plants A and B, respectively. At the production rates
of 533 metric tons/hr and 631 metric tons/hr, the mean emission
factor for these two plants is 0.0918 g/metric ton ± 0.662
g/metric ton at the 95% confidence level. The respirable emis-
sion rate from Plant B is 0.00263 g/s, resulting in a factor of
0.0147 g/metric ton.
h. Conveying
At Plant A emission rates of 0.0171 g/s and 0.262 g/s for respi-
rable and total particulates, respectively, yield emission factor
of 0.113 g/metric ton and 1.73 g/metric ton.
i. Unloading of Trucks
At Plant'B the 2.37-g respirable emission dose, based on the
unloading, of a 32 metric ton truck, gives a factor of 0.0746
g/metric ton. At Plant A the respirable emission rate of 0.005
g/s at the production rate of 533 metric tons/hr produces a
factor of 0.033 g/metric ton. The mean emission factor is 0.0538
± 0.264 .g/metric ton at the 95% confidence level. For total
particulates, at Plant B the dosage of 6.65 g for a 32 metric
ton truck yields a factor of 0.209 g/metric ton. At Plant A the
mean emission rate of 0.00669 g/s at 533 metric tons/hr results
in a factor of 0.0442 g/metric ton. The mean factor is 0.127
± 1.05 g/metric ton (at the 95% confidence level).
j.' Loading of Trucks
The mean dose rate for total particulates from both plants is
5.28 g. Loading a 32 metric ton truck gives a factor of 0.166
g/metric ton. The respirable particulate rates of 0.022 g/s
and 0.00149 g/s yield a factor of 0.0453 g/metric ton.
64
-------
k. Wet Unpaved Road Traffic
The diffusion equation used for unpaved road emissions is (33)
(C-l)
(C-l)
where D = dosage, g-s/m3
ir = 3.14
u = wind speed / m/s
a = vertical dispersion/ m
QL = line dose rate,, g/m
At a respirable particulate concentration of 20 yg/m3, once a
240-second period, at a distance of 36.6 m and a wind speed of
1.25 m/s, two vehicles emit particulates at the rate of 0.00864
g/vehicle-meter. At a total particulate concentration of 114
yg/m3, the emission rate is 0.0492 g/vehicle-meter. The res-
pirable emission factor (ER) is calculated for the average
unpaved road distance of 750 meters traveled by the average of
17 vehicles per hour as follows:
8.64 x 10-3 g)(l7 veh.
veh.-m A hr
533 metric tons/hr l<~-
converted to:
E_ = 0.202 g/metric ton
rt
The total emission factor is calculated in the same manner to
be 1.15 g/metric ton.
Using the data given in Appendix A.I, the emission factors for
NOX and CO were determined. At Plant A there were 20,426 metric
tons of rock blasted using 6.08 metric tons of ANFO. Every
kilogram of ANFO used creates 0.00625 cubic meters of NOX. The
emission factor was thus calculated and converted to 2.85
g/metric ton. For carbon monoxide, there was 0.00873 m3 of CO
(33) Gifford, F. A., Jr. Chapter 3 - An Outline of Theories
of Diffusion in the Lower Layers of the Atmosphere. In:
Meteorology and Atomic Energy 1968, Alade, D. A. (ed.).
Publication 'No. TID-24190, .U.S. Atomic Energy Commission
Technical Information Center, Oak-Ridge, Tennessee, July
1968. p. 445.
65
-------
produced per kilogram of ANFO used, and the emission factor was
1.68 g/metric ton.
3. ANALYTICAL RESULTS
Results of the elemental, free silica, and fiber analyses are
presented in Tables C-3, C-4, and C-5, respectively. The only
hazardous constituent of the dust is the free silica (Table C-3).
The mean free silica content is 1.57% (Table C-4). The emission
factor for respirable and total particulates containing free
silica is then computed from these data. However, if greater
than 1% free silica is detected, the entire emissions are con-
sidered free silica - thus the emission factors are equivalent
to the particulate emissions factors.
The fiber analysis of Table C-5 measured all fibers for pre-
liminary analysis purposes. No attempt was made to determine
which fibers were asbestos. At 62 meters downwind from the
blasting operation, the fiber concentration was 5.4 fibers/ml (or
5.4 x 106 fibers/m3).
4. COMPUTATION OF ERROR IN EMISSION RATE
The value of emission rate, Q, is determined in the field by
application of Gaussian dispersion equations to the concentrations
obtained with the high-volume and GCA samplers. These emission
values have a standard deviation which is a function of the
standard deviation of the variables. The emission rate is
calculated using Turner's (23) estimates of atmospheric disper-'
sion from ambient measurement of •£. In high-volume samplers,
there' is an error due to inconsistent airflow rates and there
are errors in time measurements and weighing which are part of
the emission error.
The values of atmospheric stability as reflected by the standard
deviations (a) in the horizontal and vertical planes are valid
for a sampling time of 10 minutes. The vertical deviation is
expected (23) to be correct within a factor of two for all
stabilities out to a few hundred meters, and neutral to moder-
ately unstable conditions in the lower 1,000 meters of the
atmosphere with a marked inversion above for distances out to 10
kilometers or more. Since all GCA samp'ling was performed within
a few hundred meters of the unit operations, these conditions
were met. For the quarrying activity (high-volume samplers) the
distance was greater; however, the emission rates calculated
were within 0.6% of their mean calculated value.
The estimate of horizontal dispersion, 0y, will be less uncertain
than that of az. The emission determined (for the three cases
cited) will therefore be within a factor of three for variations
of ay, az and u (23). Hence, the overall standard deviation
(a) in determining emission rate can be estimated as follows:
66
-------
TABLE C-3. ELEMENTAL ANALYSIS OF EMISSIONS FROM CRUSHED STONE QUARRIES
(percent)
Element
Silicon
Calcium
Sodium
Iron
Aluminum
Magnesium
Titanium
fin
Chromium
Lead
Vanadium
Manganese
Copper
Nickel
Zirconium
Silver
Zinc
Molybdenum
Boron
Plant A,
Quarry
4.8 to 14.3
2.4 to 4.7
4.8 to 14.3
2.4 to 4.8
2.4 to 4.8
0.33
0.24
0.19
0.14
0.1
0.1
0.04
0.04
<0.005
Blasting
3.0. to 9.1
3.0 to 9.1
3.0 to 9.1
1.5 to 3.0
1.5 to 3.0
0.9
0.21
0.012
0.012
0.012
0.06
0.024
0.03
<0.006
<0.006
<0.003
Plant B
Primary
crusher
11.8 to 35.3
5.9 to 11.8
5.9 to 11.8
5.9 to 11.8
5.9 to 11.8
2.4
0.7
0.024
0.47
0.51
0.035
0.094
0.12
0.005
0.005
0.007
0.47
0.24
0.12
Plant
activity
6.3 to 18.
3.2 to 6.
6.3 to 18.
3.2 to 16.
3.2 to 16.
1.9
0.5
0.12
0..01
0.19
0.025
0.06
0.13
0.006
0.025
0.025
0.252
0.0'44
9
3
9
3
3
Cation elemental analysis is shown as percent by weight of total
material; oxides and carbonates predominate the anion form.
Note: Blanks indicate that element concentration is below the
detection limit of the instrument.
67
-------
TABLE C-4. FREE SILICA ANALYSIS FROM
CRUSHED STONE QUARRIES
Sample Free silica, %
Plant A
Background 1.44
Quarrying 2.31
Blasting 2.43
Primary crusher 0.78
Mean 1.74
Plant B
Plant activity • 1.4 •
Mean of Plants A and B 1.57
Standard deviation 0.24
±95% Confidence interval 2.16
TABLE C-5. FIBER ANALYSIS FROM CRUSHED STONE QUARRIES
A fiber is a particle greater than 5 ym in length with an L/D-
of 3 or greater.
• Sampling results:
Field area = 0.005 mm2
Count =100 fields ...
Average count per field (sample of blasting emission
from Plant B) = 0.16
• Fiber concentration at 62 meters (204 ft) from the
source = 5.4 fibers/ml
• Emission factor for fibers = 128 x 106 —fibers
metric ton
• Maximum source severity (at 410 m) = 0.018
• Affected population due to emissions from a represen-
tative crushed stone plant = zero
68
-------
(C-3)
where a1 = estimated population standard deviation from
sampling for X
02 = additional standard deviation in calculation
of Q from X
A factor of three is defined as follows:
X' + 02 = o ' ic 4S
X' - 02 '
where X' = any average value calculated or measured.
From Equation C-4, a factor of three in the calculation of
Q implies:
02 = 0.5 X1 (C-5)
Therefore, all values of emission rate computed in this document
are correct within the "factor" as defined in the above discussion.
69
-------
APPENDIX D
COMPARISON OF EMISSION RESULTS WITH PREVIOUS STUDIES
This appendix provides a comparison of the emission data obtained
during this study to that reported earlier. The approaches that
were used to determine the emission factors in each study are
also briefly discussed.
Table D-l gives the emission factors as determined by MRC sam- .
pling and also as estimated in the Compilation of Air Pollutant
Emission Factors (34). As noted in the table, the MCR emission
factors are two orders of magnitude less than those estimated in
Reference (34). Possible explanations for these differences are
given below.
MCR emission factors were determined by measuring ambient air
concentrations around a source and calculating the emission rate
using a dispersion equation. The samplers were placed about
30 m to 40 m away from the source and thus did not measure par-
ticles that settled between the source and the samplers. For a
4.47 m/s (10 mph) wind speed and an emission height of 3 m,
particles greater than 74 ym settle within 35 m of the source.
The emission factors estimated in Reference (34) were based on
the results of sampling the dust loading at the inlet of a bag-
house (used to control dust emissions from various crushing and
screening operations) and on the assumption that about 41% of
the emitted particulates settle within the plant. This method
has two shortcomings: first, the total particulate emission
factor as determined by the dust loading at a baghouse inlet is
itself an inflated value; second, the estimated fraction of
settleable particulates is lower than the actual value.
A baghouse system, by virtue of its relatively high airflow
velocity, pulls in particles which otherwise would not be air-
borne at all. Further, the higher airflow velocity coupled with
the slight negative pressure in the ducting leading to the
baghouse causes the evaporation of moisture that normally would
(34) Compilation of Air Pollutant Emission Factors. Office of
Air Programs Publication No. AP-42, U.S. Environmental
Protection Agency. Research Triangle Park, North Carolina,
February 1972.
70
-------
TABLE D-l. EMISSION FACTORS OBTAINED FROM TWO STUDIES
Reference 34
Operation
Primary crushing
Secondary crushing
and screening
Tertiary crushing
and screening
Fines milling
Recrushing and
screening
TOTAL
Uncontrolled
total
emissions,
g/metric ton
250
750
3,000
3,000
2,500
9,500
% Settling
in plant
80
60
. 40
25
50
41
Suspended
emissions,
g/metric. ton
50
300
1,800
2,250
1,250
5,605
Total
particulate
emissions,
g/metric ton
13
. 1
0.4
0.1
14.5
MRC
%
Respirahle
emissions
10
55
18
16
15
Respirable
emissions,
g/metric ton
1.3
0.6
0.1
0.2
2.2
Note: Blanks indicate no data reported.
-------
bind the smaller particles together. This enables the fine and
smaller particles to break away and escape into the atmosphere.
Finally, the heavier particles collide with each other, breaking
up into smaller and finer particles. Obviously, an emission
factor for total particulates that is based on the dust loading
at the inlet to a baghouse is thus an inflated value that does
not represent the uncontrolled emissions.
Since details on particle-size distribution are not available,
it is difficult to estimate the fraction of settleable particu-
lates. However, by comparing the uncontrolled total particulate
emissions with the MRC value for total particulate emissions it
can be seen that the fraction used should have been 99% plus and
not 41% as assumed in estimating the -emission factor for suspended
particulates in Reference 35.
The emission factor for emissions from the baghouse outlet is
about 14 g/metric ton (taking the efficiency of collection as
99.8%). This is nearly equal to the MRC value (for total par-
ticulate emissions) of 14.5 g/metric ton. This implies that the
emissions which are leaving a baghouse, on this type of operation,
are still essentially all in the suspendable range. It also
implies that in this application the baghouse system does nothing
to reduce the emissions leaving the plant boundaries, since the
bulk of the previously reported emissions are not transportable
by air. At the representative distance of 410 m, particles
greater than 20 um settle and thus do not contribute to the am-
bient (public exposure) concentrations.
Finally, the purpose of determining an emission factor is to
estimate the ambient air concentrations due to several con-
tributors within a source. The sampling method outlined in this
report allows a more realistic estimate of source emissions than
that previously reported since it is based upon measurements of
air concentrations around the contributing source of interest.
(35) Blackwood, T. R.,' and R. A. Wachter. Source Assessment:
Coal Storage Piles. Contract 68-02-1874, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina.
(Final document submitted to the EPA by Monsanto Research
Corporation, October 1975.) 109 pp.
72
-------
APPENDIX E
SOURCE SEVERITY CALCULATIONS
This appendix provides examples of the procedures used to calcu-
late the severity and affected population for free silica par-
ticulates, NOX, CO, and fibers. The effect of growth factor
and control technology on emissions is also briefly described.
For ground level sources, the severity for respirable particu-
lates is given as (35):
S = "'"-" v (E-l)
Where S = source severity
Q = representative mass emission rate, g/s
D = representative distance from the source, m
For crushed stone operations, the emission factor is 3.25 g/
metric ton. The emission rate from a representative plant
.of 454 metric tons/hr (500 tons/hr) is the product of the emis-
sion factor and the production rate:
^454 metric tonsW 3.25 g \ _ 1,476 g = 0.41 g
hr I^metric tony ' hr s
At the representative distance of 410 m, the source severity
is calculated from Equation E-l as 0.03.
The distance at which the severity equals 0.1 for respirable
particulate is computed from rearranged Equation E-l:
/4,020
S=0.1 I S I (E_2)
_ (4,020) (O
DS=0.1 ~ \ OTl = 209
Since this occurs within the plant boundaries, the population
affected is zero.
73
-------
For free silica particulates emitted by ground level sources,
the severity is given as (35):
c = 316 Q
P TLV • Dl-8.1* . (E-3)
At a mean free silica content of 1.6% by weight (see Table
C-4, Appendix C), the threshold limit value is calculated (from
Equation B-9, Appendix B) as 2.78 mg/m3. The source severity
is then calculated from Equation E-3 as 0.85.
The distance at which the severity equals 0.1 for free silica
particulate is computed from rearranged Equation E-3 to:
n _/ 316 Q \l/i.8if
s=o.i ITLV • sy (E-4)
Therefore, at S = 0.1, Dn , = 1,333 m.
U • X
The population affected within the boundary of 410 m to 1,333 m
is computed by subtracting the area of a circle, with a diameter
of 1,333 m from the area of a circle with a diameter equal
to 410 m and this is found to be 1.26 km2. The population
affected is the product of the area affected and the population
density of 137 persons/km2, or 172 persons.
The source severity for NO is calculated from Equation E-5 (35)
A
22,200 Q
N0x ~ D1'9 (E~5)
Severity is thus 0.089 at 410 m, and the affected population
is thus zero. Severity for CO is calculated from Equation
E-6 (35):
_ 44.8 Q
CO nl.81 (E-6)
jj
The carbon monoxide severity is thus 1.7 x 10-"*.
Severity for fibers is calculated from Equation E-3 described
earlier:
c - 316 Q
SF - TLV . Di.8m (E-3)
Using an emission factor of 128 x 106 fibers/metric ton for
the 454 metric ton/hr representative plant, and using the TLV
for asbestos fibers of 5 fibers/ml, the severity is thus 0.019.
The growth factor is computed from the ratio of the 1978 emissions
to the 1972 levels. Production for 1978 is first calculated
by applying the production increase of 3.5% to 5.0 %/yr (Section
VI) to the 1972 production levels. The 1978 production level
74
-------
is thus a mean value of 1.373 x 108 metric tons. The 1978
emissions are calculated by applying the best available control
technology. The efficiency of this control technology is applied
to the emission factors for each of the unit operations (see
Table 1).
As shown in Section V, the best control technology for crushing
and screening operations, which have a composite emission factor
of 14.47 g/metric ton, is wet suppression. Properly installed
suppression systems can attain efficiencies of 99.8% (by weight).
The crushing and screening emission factor could therefore
be reduced to 0.03 g/metric ton.
The use of water-filled plastic bags may reduce blasting emis-
sions up to 80% for a possible reduction of the emission factor
from 0.052 g/metric ton to 0.01 g/metric ton.
The drilling emission factor was calculated for wet drilling
operations and it will not be reduced from 0.158 g/metric ton.
Wet suppression systems applied to conveying operations can
reduce emissions up to 95%. Their emission factor thus becomes
.0.09 g/metric ton.
Transport on unpaved roads is controlled by wetting the surface,
and the emission factor for this operation was computed for
a wetted road; it will thus remain unchanged.
No feasible (economical or practical) controls are available
for loading or unloading trucks or for quarrying.
The new emission factor for total particulates, after applying
the best control technology available, is 12.23 g/metric ton.
This represents a 57% reduction of the 28.36 g/metric ton 1972
level. Multiplying the 1978 production level of 1.373 x 108
metric tons by this factor'yields emissions of 1,679 metric
tons/yr of total particulates in 1978. The ratio of 1978 to
1972 emissions (with controls applied) is thus 0.55.
75
-------
GLOSSARY
amorphous: Without stratification or other division; uncrys-
tallized.
ANFO: Ammonium nitrate and fuel oil mixture used as an explosive.
azimuth: Horizontal direction expressed as the angular distance
between the direction of a fixed point (as the observer's
heading) and the direction of the object.
basalt: Hard, heavy, dark volcanic rock, sometimes found in
the form of columns.
calcareous marl: Crumbly soil consisting of clay, sand and
calcium carbonate.
cone crusher: _Vertical shaft crusher having a conical head.
confidence interval: Range over which the true mean of a popu-
lation is expected to lie at a specific level of confidence.
criteria pollutant: Pollutant for which ambient air quality
standards have been established.
cutback asphalt: Cement which has been liquefied by blending
with petroleum solvents, as rapid curing and medium curing
liquid asphalts.
diabase: Dark colored igneous rock made up largely of augite
and feldspar.
dustiness index: Reference used in measuring the amount of
dust settled where a material is dropped in an enclosed
chamber..
dynamite: Powerful explosive of nitroglycerin soaked into
an absorbent.
emission burden: Ratio of the total annual emissions of a
pollutant from a specific source to the total annual state
or national emissions of that pollutant.
fibrosis: Abnormal increase in the amount of fibrous connective
tissue in an organ or tissue.
76
-------
free silica: Crystalline silica defined as silicon dioxide
(Si02) arranged in a fixed pattern (as opposed to an
amorphous arrangement).
granite: Very hard igneous rock, usually gray or pink, consist-
ing chiefly of crystalline quartz, feldspar, and mica.
graphite: Soft, black, lustrous form of carbon.
gyratories: Crushers that move in a circular or spiral path.
hazard factor: A measure of the toxicity of prolonged exposure
to a pollutant.
igneous: Produced by the action of fire, formed by volcanic
action or great heat.
jaw crushers: Crushers that give a compression or squeeze
action between two surfaces.
lignin sulfonates: Organic substances forming the essential
part of woody fibers introduced into the sulfonic group
by treatment with sulfuric acid.
limestone: Rock consisting mainly of calcium carbonate.
marble: Hard crystalline or granular metamorphic limestone.
metamorphic: Changed in structure by pressure, heat, chemical
action, etc.
mica schist: Group of minerals that crystallize into thin,
easily separated layers.
noncriteria pollutant: Pollutant for which ambient air quality
standards have not been established.
Precipitation-Evaporation index: Reference used to compare the
precipitation and temperature levels of various P-E regions
of the U.S.
processing plant: That portion of the quarry where the operation
of crushing and size classification of stone occurs.
pulverizer: Crusher used to reduce stone size into powder or
dust.
quarry:' Term used to refer to the mining, processing plant,
and material transfer operations.
77
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representative source: Source that has the mean emission
parameters.
respirable particulates: Those particles with a geometric
mean diameter of <1 ym.
riprap: Large, irregular stone (>4 in.) used in river and
harbor work and to protect highway embankments.
rock: Stone in a mass.
sandstone: Common sedimentary rock consisting of sand grains,
usually quartz., cemented together by silica, lime, etc.
scalping screen: Screen used to prescreen the feed to crushers.
sedimentary: Matter .or mass deposited by wind or water.
serpentine: A mineral, irvagnesium silicate, usually green or
brownish red; often mottled.
severity: Hazard potential of a representative source defined
as the ratio of time-averaged maximum concentration to
the hazard factor.
shale: Fine grained rock formed by the hardening of clay which
splits into layers when broken.
shell marble: Crystalline or granular metamorphic limestone
with a hard outer coating.
shortheads: Refers to a cone crusher.
shuttle conveyor: Conveyor used to move crushed stone back
and forth between operations.
silicpsis: Chronic disease of the lungs caused by the continued
inhalation of silica dust.
silt-sized: Fine particle sized, as soil or sand.
sizing screen: Mesh used to separate stone into various sizes.
slate: Hard, fine-grained rock that cleaves naturally into
thin, smooth-surfaced layers.
stone: Hard, solid, nonmetallic mineral matter of which rock
is composed.
surge pile: Stockpile near a crusher used to accomodate crushed
stone that cannot be transported away fast enough.
78
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thixotropic: Relating to a property of gels to become liquid
when shaken or disturbed.
threshold limit value: The concentration of an airborne con-
taminant to which workers may be exposed repeatedly, day
after day, without adverse affect.
traprock: Dark, dense and fine-grained igneous rock.
79
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO
EPA-6QO/2-78-004L
2.
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
SOURCE ASSESSMENT:
5. REPORT DATE
CRUSHED STONE
May 1978 issuing date
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
T. R. Blackwood, P. K. Chalekode, and
R. A. Wachter
8. PERFORMING ORGANIZATION REPORT NO.
MRC-DA-536
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
10. PROGRAM ELEMENT NO.
1BB610
11. CONTRACT/GRANT NO.
68-02-1874
12. SPONSORING AGENCY NAME AND ADDRESS
Industrial Environmental Research Lab-Cinn., OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati. nhio.4B?P.R
13. TYPE OF REPORT AND PERIOD COVERED
Task Final, 3/75-2/76
14. SPONSORING AGENCY CODE
EPA/&00/12
15. SUPPLEMENTARY NOTES ' ,
IERL-Ci project leader for this report is John F. Martin,
513/684-4417.
16. ABSTRACT
This report describes a study of atmospheric emi/ssions from the crushed
stone industry. Atmospheric emissions of respifable particulates (<7ym)
occur in the mining from the open quarry and in the processing at the
crushing and screening plant. The emission factor for respirable parti-
culates from the entire facility is 3.25 g/metric ton ±2.54 g/metric ton
at the 95% confidence level. Free silica comprises 1.6% of these parti-
culates by weight. The primary crusher and quarrying unit operations
account for 73.5% of the respirable particulates. The emission factor
for total particulates is 28.4 g/metric ton ±24.5 g/metric ton at the
95% confidence limit. In order to evaluate the potential environmental
effect of crushed stone plants, a severity factor was defined as the
ratio of the maximum ground level concentration of an emission to the
ambient air quality standard for criteria pollutants and to a modified
threshold limit value for other pollutants. The maximum factors for a
representative crushed stone plant are 0.03 and 0.83 when the emissions
are treated as respirable particulates and free silica, respectively.
Total particulate emissions from crushed stone production account for no
more than 0.02% of the total national particulate emissions. No emergin
technology of specific importance to air pollution control in the crushe
industrywasfoundinthisstudy.
J KEY WORDS AND DOCUMENT ANALYSIS
stone
17.
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
COS AT I Field/Group
Air pollution
Rocks
Mining
Silicon dioxide
Nitrogen oxides
Carbon monoxide
Air Pollution Control
Stationary Sources
Source Severity
Particulate
68A
13, DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
1S.SECUR1TY-C1-ASS (Thi* Rtnortl
UNCLASSIFIED
21.NQ-.QF PAGES
94
20 SECURITY CLASS IThis Dazel
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
80
.U.S. GOVERNMENT PRINTING OFFICE: 1978-757-140/6847 Region No. 5-11
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