United States
Environmental Protection
Agency
Industrial Environmental
Research Laboratory
Cincinnati OH 45268
EPA-600/2-78-004e
April 1978
Research and Development
&EPA
Source Assessment:
Crushed Limestone,
State of the Art
Environmental Protection
Technology Series
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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 repair or prevent en-
vironmental degradation from point and non-point sources of oollution. 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-600/2-78-004e
April 1978
SOURCE ASSESSMENT:
CRUSHED LIMESTONE
State of the Art
by
P. K. Chalekode, T. R. Blackwood, and S. R. Archer
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
Contract No. 68-02-1874
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.
11
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FOREWORD
When energy and material resources are extracted, processed,
converted, and used, the related pollutional impacts on our
environment 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 effi-
ciently and economically.
This report contains an assessment of air emissions from the
crushed limestone industry. This study was conducted to provide
a better understanding of the distribution and characteristics of
emissions from crushed limestone operations. 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 Federal Water Pollution Control Act, and solid waste legisla-
tion. If control technology is unavailable, inadequate, uneconom-
ical, or socially unacceptable, then financial support is
provided for the development of the needed control techniques for
industrial and extractive process industries. Approaches" con-
sidered include process modifications, feedstock modifications,
add-on control devices, and complete process 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 of operations (more than 500) in the chemical and
related 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.
Monsanto Research Corporation (MRC) has contracted with EPA to
investigate the environmental impact of various industries that
represent sources of pollutants in accordance with EPA's respon-
sibility, 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 materi-
als, and open sources. Dr. Dale A. Denny of the Industrial
Processes Division at Research Triangle Park serves as EPA Proj-
ect Officer for this series. Reports prepared in this program
are of two types: Source Assessment Documents and State-of-the-
Art Reports.
Source Assessment Documents contain data on pollutants from
specific industries. Such data are gathered from the literature,
government agencies, and cooperating companies. Sampling and
analysis are also performed by the contractor when the available
information does not adequately characterize the source pollut-
ants. These documents contain all of the information necessary
for IERL to decide whether a need exists to develop additional
control technology for specific industries.
IV
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State-of-the-Art Reports include data on pollutants from specific
industries which are also gathered from the literature, govern-
ment agencies and cooperating companies. However, no extensive
sampling is conducted by the contractor for such industries.
Sources in this category are considered by EPA to be of insuffi-
cient priority to warrant complete assessment for control technol-
ogy decisionmaking. Therefore, results from such studies are
published as State-of-the-Art Reports for potential utility by
the government, industry, and others having specific needs and
interests.
This State-of-the-Art Report contains data on air emissions from
the crushed limestone industry. This project was initiated by
the Chemical Processes Branch of the Industrial Processes Divi-
sion at Research Triangle Park; Mr. D. K. Oestreich served as EPA
Project Leader. The project was transferred to and completed by
the Resource Extraction and Handling Division, lERL-Cincinnati,
under Mr. John F. Martin.
v
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ABSTRACT,
This report describes a study of air pollutants emitted by the ,
crushed limestone industry. The potential environmental effect '
of, the source was evaluated using source severity (defined-as the
ratio of the maximum ground level concentration of an emission to
a hazard factor).
• , '•.,,••* ..'.'*
In 1972, there were 1,374 crushed limestone processing plants
operating 2,904 quarries in the United States. The representa-
tive crushed limestone plant produces 450 metric tons/hr and
emits particulates from several operations, including drilling,
blasting, transport on unpaved roads, crushing, screening, con-
veying, and stockpiling. The emission factor for total particu-
lates emitted from the representative plant is 3.5 g/metric ton,
and vehicular movement on unpaved roads contributes 66% of the
overall emissions. Approximately 38% of the respirable particu-
late emissions originate from vehicular movement on unpaved
roads, and the respirable particulate emission factor is 0.6
g/metric ton. The hazardous constituent in the dust is free
silica ,. (1.2% by weight), prolonged exposure to which may result
in the development of a pulmonary fibrosis known as silicosis.
Nitrogen oxides and carbon monoxide are emitted by the blasting
operation, but the emission factors (and source severities) for
these emissions are small in comparison to those of particulate
emissions.
The maximum source severity for particulates is calculated as
0.032. The affected population is defined as the population
living beyond the plant boundary where the severity is 0.1 or. \
greater. The population affected by a severity of 0.1 due to
total particulate emissions is thus zero. Similarly, the source
severity due to free silica in the respirable particulate emis-
sions is 0.12, and the population affected by a severity of 0.1
is 11 persons. The emissions from the crushed limestone industry
(as well as the output of the industry) are estimated to be the
same in 1978 as they were in 1972. :
This report was submitted in partial fulfillment of Contract
68-02-1874 by Monsanto Research Corporation under the sponsorship
of the U.S. Environmental Protection Agency. The study covers
the period August 1975 to February 1976.
VI
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CONTENTS
Foreword iii
Preface iv
Abstract vi
Figures .......> viii
Tables viii
Abbreviations and Symbols ix
Conversion Factors and Metric Prefixes xi
1. Introduction 1
2. Summary 2
3. - Source Description 5
Process description ........ 5
Factors affecting emissions 7
Geographical distribution 8
4:. Emissions 10
Selected pollutants ' . .10
Characteristics 10
Definition of representative source ....... .11
Source severity 13
5. Control Technology 16
State of the art 16
Future considerations 16
6. Growth arid Nature of the Industry 20
Present technology ,20
Emerging technology f ,20
Production trends 20
/
References 22
Appendices
A. Literature survey 25
B. Sampling details and results 31
C. Source severity and affected population 46
Glossary 49
VII
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FIGURES
Number Page
1 Simplified flowsheet for lime and limestone products. .6
TABLES
1 Mass Emissions from Various Operations in the
Crushed Limestone Industry 4
2 .Crushed Limestone Sold or Used by Producers in the
United States in 1972, by State and Respective
Population Density 9
3 State and Nationwide Particulate Emission Burdens
from Crushed Limestone 12
4 Pollutant Severity Equations 15
5 Source Severity and Affected Population for Emis-
sions from the Crushed Limestone Industry 15
Vlll
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ABBREVIATIONS AND SYMBOLS
A — cross-sectional area of the falling granules, cm2
a. . .d, f -- variable exponents and coefficients used in numer-
ous methematical manipulations
B — width of conveyor belt, cm
CHI — measured concentration less background, yg/m3
D — representative distance from the major source, m
D — total dose, g-s/m3
e — natural logarithm base, 2.72
E — emission factor, g/metric ton
E — function of five variables that influence dust
emissions from drilling operations
F — hazard factor, g/m3
G — gravitational acceleration, 980 cm/s2
H — height of material fall, cm
mi' m2 — slopes used in calculating distances to samplers
M — belt load, g/cm2
P — production rate of crushed limestone, metric tons/hr
Q — emission rate, kg/hr or g/s (Equations 1 and 2)
Qn — line source emissions per length of line, g/m
Q_ — total release, g
R — specific formation of airborne respirable dust, g
S — maximum source severity, dimensionless
SQ. • -Si). — high-volume sampler locations
TLV — threshold limit value, g/m3
u — 4.5 m/s (approximate U.S. average wind speed)
UD — linear speed of the conveyor belt, cm/s
D
x — downwind distance
x., y. — Cartesian coordinates used to relate position of
1 1 the ith sampler to the source
IX
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ABBREVIATIONS AND SYMBOLS
X, X. — downwind distance from source along the dispersion
centerline
x — crosswind distance from the line source, m
c • . ~ ' ' v..
Y, Y. — lateral distance from dispersion centerline to
sampler, m
Z — vertical distance from the X-Y plane of the source
to the sampler plane
a — angle defined for use in calculating sampler
position, rad <
9 — wind azimuth angle with respect to the y axis, rad
TT — a constant, 3.14
"pc — material density of coal, g/cm3
a — overall standard deviation, m
0 ' — horizontal standard deviation of plume dispersion, m
a — vertical standard deviation of plume dispersion, m
Z
a T — instantaneous vertical dispersion parameter, m
Z _L '
X — ground level concentration, g/m3
X- — ground concentration at coordinate location (X.,
1 Y±, 0), g/m3 1
X — maximum ground level concentration, g/m3
max
X~ — maximum time-averaged ground level concentration,
max g/m3
ijj — dose, g-s/m3
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CONVERSION FACTORS AND METRIC PREFIXES9
To convert from
Centimeter
Centimeter2, (cm2)
Centimeter3 (cm3)
Kilogram (kg)
Kilogram (kg)
Kilometer2 (km2)
Meter (m)
Meter2 (m2)
Meter3 (m3)
Meter 3; (m3)
Metric, ton
Radian (rad)
CONVERSION FACTORS
To
Multiply by
Foot
Inch2
Inch3
Pound-mass
Ton (short.
Mile2
Toot
Foot2
Foot3
Gallon (U'.S
Pound-mass
Degree (°)
(avoirdupois)
2,000 Ib-mass)
. liquid)
3.281 x 10~2
1.550 x ID"1
6.102 x 10~2
2.204
1.102 x 10~3
3.860 x 10-1
3.281
1.076 x 101
3.531 x 101
2.642 x 102
2.205 x 103
5.730 x la1
Prefix Symbol
Kilo
Centi
Milli
Micro
k
c
m
., METRIC PREFIXES
Multiplication factor
103
lO-2
10~3
10-6
Example
1 kg
1 cm
1 mm
1 m
1 x 103 grams
1 x 10~2 meter
10~3 meter
r*
mt*. •*». J- \S J.ll>_~ ^.^,^.
= 1 x 10~6 meter
= 1 x
Metric Practice Guide. ASTM Designation E 380-74, American
Society for Testing and Materials, Philadelphia, Pennsylvania,
November 1974. 34 pp.
XI
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SECTION 1
INTRODUCTION
The conversion of naturally occuring limestone to a crushed form
involves mining from open quarries and processing at finishing
plants. The mining and processing operations create air pollu-
tion problems.
An investigation of crushed limestone operations was conducted to
provide a better understanding of the distribution and character-
istics of emissions from these activities than had been previously
available in the literature. Data collection emphasized the accu-
mulation of sufficient information to ascertain the need for devel-
oping control technology in this industry.
This document contains information on the following items:
• A method to estimate the emissions due to crushed
limestone processing
• Composition of emissions
« Hazard potential of emissions
• Geographical distribution and source severity
• Trends in the crushed limestone industry and
their effects on emissions
• Type of control technology used and proposed
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SECTION 2
SUMMARY
The crushed limestone industry converts naturally occurring lime-
stone deposits to a form that is used predominantly (67% of the
output) by the construction industry. The 1,374 processing
plants, which operate 2,904.quarries in the United States, pro-
duced 6.1 x 108 metric tons of crushed limestone in 1972. This
represented 37% of the output of the aggregate industry (crushed
limestone, granite,$stone, sand and gravel, and sandstone, quartz
and quartzite). Contingency forecasts of crushed limestone
demands in the year 2000 have been reported to be 1.2 x 109
metric tons to 2.0 x 109 metric tons.
Atmospheric emissions of particulates occur from several unit
operations: drilling, blasting, transport on unpaved roads,
crushing, screening, conveying, and stockpiling. The estimated
emission factor available in the published literature, 5.65 grams
of suspended particulate per kilogram of processed material, was
checked by onsite sampling. The emission factor for total partic-
ulates from crushed limestone processing is 3.5 g/metric ton, and
the emission factor for respirable.particulates is 0.6 g/metric
ton. Total particulate emissions from vehicular movement on
unpaved roads (between quarry and plant) contribute about 66% of
the overall emissions. Similarly, about 35% of the respirable
particulate emissions are from vehicular movement on unpaved
roads. The hazardous constituent in the dust is free silica
(1.2% average), prolonged exposure to which may result in the
development of silicosis.
The total national emissions from the crushed limestone industry
account for less than 0.013% of national emissions and less than
0.07% of any state emissions.
A representative crushed limestone plant produces 450 metric
tons/hr and emits dust at the rate of 0.27 kg/hr respirable
particulates (less than 7 ym) and 1.6 kg/hr total particulates
(less than 100 ym).
To assess the source severity, the ratio of the maximum time-
averaged ground level concentration at the representative plant
1 metric ton equals 106 grams; conversion factors and metric
system prefixes are presented in the prefatory material.
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boundary to the pollutant hazard factor is used. The hazard
factor is defined as the EPA primary air quality standard. When
EPA criteria do not exist, an adjusted threshold limit value
(TLV®) is used which corrects for exposure time and for the
exposure of the general population. The maximum source severity
due to free silica emissions (respirable fraction) from a repre-
sentative plant is 0.14.
Nitrogen oxides and carbon monoxide are emitted by the blasting
operation with respective emission factors of 2.85 g/metric ton
and 1.68 g/metric ton of material blasted. The maximum source
severities due to nitrogen oxides and carbon monoxide are 0.089
and 1.7 x 10\ respectively.
Table 1 summarizes the severity and contributions of total partic-
ulates and free silica emissions from the various unit operations.
This industry is concentrated near limestone deposits, adjacent
to large, rapidly expanding urban areas, and in areas where
largescale public and private works are under construction. The
distribution of plants with respect to the size of localities
shows that free silica emissions from a representative crushed
limestone plant affect a population of 11 persons down to a
severity of 0.1. The affected population is based on respirable
particulate emissions.
The output of the industry and its emissions are estimated to be
the same in 1978 as they were in 1972.
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TABLE 1. MASS EMISSIONS FROM VARIOUS OPERATIONS IN THE CRUSHED LIMESTONE INDUSTRY
Unit operation
Drilling
Blasting
Loading at
the. quarry
Vehicular
trafficb
Primary
crushing
Primary
screening
Secondary
crushing
Screening
screening
Conveying
Stockpiles
Unloading at
stockpiles
TOTAL0
Emission factors,
q/metric ton
0.11
0.075
0.0015
2.3
0.56
0.0016
0.14
0.0009
0.32
a
_a
3.5
Total
U.S. total,
kg/yr
67 , 000
46,000
9,000
1,403,000
341,000
9,800
85,000
5,500
195,000
_a
_a
2,135,000
particulates
Severity for
Percent representative
of total plant
3 -3
2 -3
_a _a
66 0.021
16 0.005
_a _a
4 0.001
_a _a
9 0.003
_a _a
_a _a
100 0.032
Free silica
Severity for
Percent U.S. total, representative
respirable kg/yr plant
10 80 -a
17 100 -3
0 00
10 1,680 0.05
30 1,240 0.04
30 -a -a
53 560 0.02
53 -a -a
30 700 0.03
-a -a _a
-a .a _a
17 4,360 0.14
Negligible.
On unpaved road between quarry and plant.
cTotal may not add to figure shown due to rounding.
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SECTION 3
SOURCE DESCRIPTION
PROCESS DESCRIPTION
Emission Sources
The conversion of naturally occuring limestone deposits into a
crushed form involves a series of physical operations similar to
those used in the crushed granite and crushed stone industries as
shown schematically in Figure 1. The deposits are first loosened
by drilling and blasting, then loaded and transported to the
processing plant by trucks or belt conveyors. Processing
includes such operations as crushing, pulverizing, screening,
conveyi-ng and stockpiling. After processing, the crushed mate-
rial can be used for construction purposes, or it can be pro-
cessed further for the manufacture of quicklime and of hydrated
lime.
Fine particulate (less than 7 ym) emission sources in the crushed
limestone industry can be divided into two categories: 1)
sources associated with actual processing, such as crushing,
screening, and transfer operations; and 2) fugitive dust sources,
such as vehicle traffic on unpaved roads, transport operations,
and stockpiles. Quarrying operations such as drilling, blasting,
and loading are also fugitive dust sources.
This study is confined to an evaluation of emissions from crushed
limestone processing and does not include those from quicklime or
hydrated lime operations (Figure 1).
Source Composition
Limestone is a sedimentary rock composed primarily of calcium
carbonate (CaC03) and secondarily of magnesium carbonate (MgCO3),
including varying percentages of impurities. Limestone is gener-
ally classified into the following types:
• High-calcium—The carbonate content is composed essen-
tially of calcium carbonate with a magnesium carbonate
content of no more than 5% (usually less).
• Magnesian—This rock, which contains both carbonates,
possesses a magnesium carbonate content of 5% to 20%.
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AREA OF STUDY
HIGH-CALCIUM AND DOLOMITIC LIMESTONE
QUARRY AND MINE OPERATIONS
(DRILLING, BUSTING AND CONVEYING
OF BROKEN LIMESTONE)
1
PRIMARY CRUSHER
o
to
>-
on
lu
oS
SCREENING AND CLASSIFICATION
I
152mm TO 203mm
LIMESTONE
jSECONDARY CRUSHING}
-
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• Dolomitic—This rock contains over 20% MgC03; however,
the maximum MgC03 content will not exceed 45.6%, the
exact amount contained in a true, pure, equimolecular
dolomite, with the balance CaCO3.
Chemical analyses of different,types of U.S. limestones show that
the lime (CaO) content ranges from about 29% to 55%, the magnesia
(MgO) content ranges from 0% to 21%, the alumina (A1203) content
is less than 6%, and the iron oxide (Fe2O3) content is less than
2% CD .
FACTORS AFFECTING EMISSIONS
Calculation of the source severity and the state and national
emissions burdens necessitates a knowledge of the emission rate
for every source in the country. Conducting emission measure-
ments on a sourcebysource basis was impractical due to the large
number of individual sources and the diversity of source types.
A method was therefore developed to derive an emission factor as
grams of particulates emitted per metric ton of crushed limestone
processed.
The emission rate for each of the source types is estimated as
the product of the emission factor and the crushed limestone
production rate. This relationship can be stated as shown in
Equation 1.
Q = E(P) (1)
where Q = emission rate of particulates, g/hr
E = emission factor for particulates, g/metric ton
of crushed limestone processed
P = production rate of crushed limestone,
metric tons/hr
The overall emissions from crushed limestone operations are due
to drilling, blasting, loading, vehicular movement on unpaved
roads (between quarry and plant), crushing, conveying, screening,
and stockpiling. Emissions from all of these unit operations
(except blasting) are influenced by particle size distribution,
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 opera-
tions to overall emissions. Although estimates of emission
(1) Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Vol. 12- John Wiley & Sons, Inc., New York,
New York, 1969. pp. 414-423.
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factors for some unit operations are available in the published
literature, no studies were conducted or reported to validate the
estimated emission factors (Appendix A).
A sampling of emissions from two crushed limestone plants was
conducted (see Appendix B for details and results of sampling).
The results show that vehicular traffic on unpaved roads between
the quarry and plant contribute 66% of the total particulate
emissions, and that primary crushing operations contribute 16% of
the overall .emissions. Similarly, 38% of the respirable par-
ticulate emissions are from vehicular traffic on unpaved roads,
and 28% of the "respirable particulate emissions are from primary
crushing operations.
The factors believed to influence emissions from vehicular move-
ment on unpaved roads are vehicle speed, vehicle weight and
crosssectional area, number of wheels, tire width, particle size
distribution, and moisture content of unpaved road surface mater-
ial. Though considerable information is available on the magni-
tude of unpaved road emissions, little has been done to correlate
the emissions with soil or vehicle characteristics.
GEOGRAPHICAL DISTRIBUTION
In 1972 there were 1,374 crushed limestone processing plants (2)
operating 2,904 quarries (personal communication with W. Pajalich,
Bureau of Mines, Washington, D.C., 15 October 1975) with a total
total output of 6.1 x 108 metric tons. Pennsylvania ranked first
with 5.1 x 107 metric tons, followed by Illinois, Florida, Ohio
Texas, Missouri, Michigan, Tennessee, New York and Kentucky.
Together, these 10 states accounted for 66% of the total crushed
limestone production in the United States (3).
Table 2 gives the crushed limestone output by state in the United
States and the respective population densities.
Geographically, the crushed limestone industry is concentrated
near limestone deposits, adjacent to large, rapidly expanding
urban areas, and in areas where large-scale public and private
works are under construction.
(2) 1972 Census of Mineral Industries, Subject Series: General
Summary. MIC 72(1)-1, U.S. Department of Commerce,
Washington, D.C., 1975. 174 pp."
(3) Mineral Industry Surveys. U.S. Department of the Interior,
Washington, D.C., 1972. 12 pp.
8
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TABLE 2. CRUSHED LIMESTONE SOLD OR USED BY PRODUCERS
IN THE UNITED STATES IN 1972, BY STATE AND
RESPECTIVE POPULATION DENSITY
Population density,
State persons/Jon2
Alabama
Arizona
Arkansas
California
Colorado
Connecticut
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
Wisconsin
Wyoming
Undistributed
TOTAL
27
7
15
50
9
240
49
31
49
4
78
57
20
11
32
12
177
274
60
18
It
27
2
8
2
366
3
145
39
2
102
15
9
103
312
34
2
38
17
5
19
46
29
31
1
Production in 1972,
10 3 metric tons
14,800
2,200
4,700
16,400
3,000
200
48,200
5,600
1,100
51,100
24,500
24,900
12,700
31,100
13,100
800
35,200
4,400
400
37,800
1,300
3,900
2,000
1,300
31,200
43,100
16,400
51,300
1,500
32,400
38,600
2,100
1,100
17,300
9,700
14,300
1,400
7,500
610,000a
Note.—Blanks denote information withheld owing to confidential
nature of data; included with "undistributed."
aData do not add to total shown due to independent rounding.
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SECTION 4
EMISSIONS
SELECTED POLLUTANTS
Emissions from crushed limestone operations are classed as nui-
sance particulates. They are considered to be toxic only when
they contain a toxic component such as free silica (4, 5).
The prolonged inhalation of dusts containing free silica may
result in the development of a disabling pulmonary fibrosis known
as silicosis. The action of silica on the lungs results in the
production of a diffuse, nodular, progressive fibrosis that may
continue to increase for several years after exposure is termina-
ted. The first and most common symptoms of uncomplicated silico-
sis are shortness of breath on exertion and a dry cough. When
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, pleuritic pain, and
total incapacity to work. Extreme cases may eventually result in
death from destruction of the lung tissues (4).
The American Conference of Governmental Industrial Hygienists has
suggested a TLV (in milligrams per cubic meter) of 10/(percent
quartz + 2) for respirable dusts containing quartz or free silica.
Dusts with less than 1% silica are termed "inert," and their
suggested TLV is 10 mg/m3 (5).
CHARACTERISTICS
Mass Emissions
The mean emission factor for respirable particulates is
0.6 g/metric ton of limestone processed through the primary
crusher. The mean emission factor for total particulates is
3.5 g/metric ton. Total particulate emissions due to vehicular
(4) Sax, N. I. Dangerous Properties of Industrial Materials,
Third Edition. Reinhold Book Corporation, New York,
New York, 1968. pp. 1088-1089.
(5) TLVs® Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment with Intended
Changes for 1976. American Conference of Governmental
Industrial Hygienists, Cincinnati, Ohio, 1976. p. 32.
10
-------
movement on unpaved roads between the quarry and plant contribute
66% of the overall emissions. Similarly, 38% of the respirable
particulate emissions are from vehicular movement on unpaved
roads. The foregoing results are based on a sampling of two
crushed limestone plants (see Appendix B). The total particulate
emission factor generated in this study is less than the estima-
ted emission factor reported in'literature published prior to
this study. The emission factors for nitrogen oxides and carbon
monoxide, respectively, are 2.85 g/metric ton and 1.68 g/metric
ton (6).
The aforementioned emission factor for total particulates was
used to estimate the statewide emissions from crushed limestone
processing, as shown in Table 3. The state emission burden is
calculated as.the percent contribution of total particulate
emission rates from crushed limestone processing in a state to
the overall total particulate emission rates in that state. Table
3 displays the state and.nationwide burdens. The emissions of
total particulates due to crushed limestone processing contribute
0.07% or less to the overall particulate emissions in each of the
states in the United States.
Composition of Emissions
h " . ^
An analysis of the emissions from crushed limestone operations
(Appendix B) shows that free silica, constituting 1% to 2% by
weight, is the only known hazardous component. Remaining con-
stituents are considered! inert.
DEFINITION OF REPRESENTATIVE SOURCE
The size of crushed limestone plants ranges from about 136 metric
tons/hr to 1,090 metric tons/hr with the average of 450 metric
tons/hr being the size of the representative plant (personal com-
munication with F. Renninger, National Crushed Stone Association,
Washington, D.C., 7 November 1975).
The mean emission factor was determined by sampling two crushed
limestone plants whose production rates were similar to that of
the representative plant (Appendix B). Thus, the representative
source emits dust at a rate of 0.27 kg/hr respirable particulates
(less .than 7 ym) and 1.6 kg/hr total particulates.
The representative population density, taken as the average pop-
ulation density of the states weighted on the basis of their
crushed limestone production, is 58, persons/km2. The representa-
tive distance from the plant is defined using the major contribu-
ting source within the plant as the reference point. The
(6) Blackwood, T. R., P. K. Chalekode, arid R. A. Wachter.
Source Assessment: Crushed Stone. Contract 68-02-1874,
U.S. Environmental Protection Agency, Cincinnati, Ohio,
July 1977. 91 pp.
11
-------
TABLE 3. STATE AND NATIONWIDE PARTICULATE EMISSION
BURDENS FROM CRUSHED LIMESTONE
State
Total participate
emissions from
crushed limestone
processing (1972),
metric tons/yr
Overall
particulate
emissions (7)
103 metric tons/yr
Contribution of
crushed limestone
emissions to
overall state
emissions, %
Alabama
Arizona
Arkansas
California
Colorado
Connecticut
Florida
Georgia
Hawaii
Illinois
Indiana
Iowa
Kansas
Kentucky
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Mexico
New York
Ohio
Oklahoma
Pennsylvania
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington
West Virginia
Wisconsin
Wyoming
Other states8
TOTAL
52
8
16
57
11
1
169
20
4
179
86
87
44
109
46
3
123
15
1
132
6
14
7
5
109
151
57
180
5
113
135
7
4
61
4
34
50
5
26
2,135
1,179
73
138
1,006
201
40
226
405
62
1,143
748
216
348
546
495
96
706
266
168
202
273
95
94
103
160
1,766
94
1,811
52
410
549
72
15
477
162
214
412
75
1,662
16,762b
0.01
0.01
0.01
0.07
0.01
0.02
0.01
0.04
0.01
0.02
0.01
0.01
0.06
0.01
0.07
0.01
0.06
0.01
0.01
0.03
0.02
0.01
0.03
0.01
0.02
0.01
0.01
0.013C
Note.—Blanks indicate negligible contribution.
Includes Idaho, Maine, New Jersey, North Carolina, North Dakota, Oregon,
Rhode Island, and South Carolina.
Includes overall particulate emissions from Alaska, Delaware, District of
Columbia, and Louisiana, which do not have crushed limestone plants.
cSince respirable particulate is 14.2% of total particulate emissions,
national emission burden due to respirable particulate emissions from
crushed limestone emissions is 0.002%.
(7) 1972 National Emissions Report. EPA-450/2-74-012, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, June 1974.
422 pp.
12
-------
distance of the plant boundaries from this reference point is
taken as the radius of a circle whose area is equal to the area
of the representative plant. The area of a representative
crushed limestone plant was assumed to be similar to that of a
representative crushed stone plant (0.53 km2), and the resulting
representative distance to the plant boundary is 410 m (6).
The output of the representative plant and its emissions should
follow industry trends; they are estimated to be the same in 1978
as they were in 1972.
SOURCE SEVERITY
The source severity, used to indicate the hazard potential of the
representative emission source, is determined using the ratio of
the maximum ground level concentration (x) to a hazard factor
(F), A mathematical model describing the dispersion of pollutants
in the atmosphere is employed to calculate the source severity, S
(which equals x/F)• F°r open sources, the model employs the con-
centration of a pollutant occurring at a ground level point
source on the plant boundary. This is the maximum concentration
that can occur at one point in time and, thus, is considered a
worst-case condition. The hazard factor is derived from ambient
air quality criteria or reduced threshold limit values.
Ground Level Concentration
The minimum distance from the major contributing emission source
to the representative crushed limestone plant boundary is 410 m,
as shown in Section 4. This is the minimum distance at which
public exposure to the pollutant could occur.
The following formula in conjunction with class C meteorological
conditions (approximate U.S. average) was used to calculate Xmax
(the maximum ground level, instantaneous concentration) (8):
xmax ~ ira a u
where Q = mass emission rate, g/s
TT = 3.14
a = 0.209 (x°-903)
ol = 0.113 (x°-911)
u = 4.5 m/s (approximate U.S. average wind speed)
The instantaneous ground level concentration for total particu-
lates at 410 m is 24 yg/m3. This must be corrected to the time-
(8) Turner, D. B. Workbook'of Atmospheric Dispersion Estimates.
Public Health Service Publication No. 999-AP-26, U.S.
Department of Health, Education, and Welfare, Cincinnati,
Ohio, May 1970. 84 pp.
13
-------
averaged maximum, Xmax' for 24 hr as described by Nonhebel (9) so
that the mean concentration becomes 8.4 yg/m3. Therefore, the
maximum ground level concentration at the boundary of the repre-
sentative plant during a 24-hr period is 8.4 yg/m3 above back-
ground levels (worst case).
Hazard Factor
Since no ambient air quality criterion exists for free silica,
the hazard factor, F, is defined as follows:
F 7 2<
The derivation of F utilizes the TLV corrected from 8-hr to 24-hr
exposure with a safety factor of 100 applied to this calculation.
The free silica hazard factor for the purposes of this report is
calculated as 10.4 yg/m3, comparable to that for respirable
emissions since the TLV is for respirable emissions. For total
particulates, F shall be defined as the 24-hr ambient air quality
standard of 260 yg/m3.
Source Severity
For the representative crushed limestone plant, the maximum
severity is determined from the ratio of the maximum time-
averaged ground level concentration_of the emission species to
the hazard factor for the species (Xmax/F)• ^e maximum time-
averaged ground level concentration is related to the.mass emis-
sion rate, Q (in grams per second) of a pollutant and, for open
sources, to the representative distance, D, from the source to
the plant boundary.
Using the approach described above, the equations in Table 4 were
used to determine the severity of criteria and noncriteria
pollutants from the crushed limestone industry (10). The equa-
tions simplify the calculation of both severity and, ultimately,
affected population.
Source severities due to and the population affected by emissions
of criteria and noncriteria pollutants from the crushed limestone
industry are shown in Table 5. Severity can also be obtained by
calculating the ratio Xmax/F- Thus for particulate (Xmax equals
8.4 yg/m3 and F equals 260 yg/m3), the severity is 0.32. Sample
calculations for source severity and affected population are
provided in Appendix C.
(9) Nonhebel, G- Recommendations on Heights for New Industrial
Chimneys. Journal of the Institute of Fuel, 33:479, 1960.
(10) Blackwood, T. R., and R. A. Wachter. Source Assessment:
Coal Storage Piles. Contract 68-02-1874, U.S. Environmental
Protection Agency, Cincinnati, Ohio, July 1977. 96 pp.
14
-------
TABLE 4. POLLUTANT SEVERITY EQUATIONS
Severity
_ Pollutant _ equation
Particulate S = 'p, (4)
U •*• » O •"•
Nitrogen oxides S = 22'?°9flQ (5)
jj i . 3 U
Carbon monoxide S = 44;80? (6)
D i * o i
Noncriteria pollutant S = (7)
TABLE 5. SOURCE SEVERITY AND AFFECTED POPULATION FOR
EMISSIONS FROM THE CRUSHED LIMESTONE INDUSTRY
Type of pollutant
Total particulates
Free silica
Nitrogen oxides
Carbon monoxide
Source
severity
0.032
0.14
0.089
0.00017
Affected
population9
0
11
0
0
Population affected down to a severity of 0.1.
Since the maximum source severity for total particulates is less
than 0.1 at the plant boundary {Appendix C) , the affected popu-
lation is zero. Similarly, the maximum source severity for free
silica in the respirable particulates is 0.14 and, for a repre-
sentative population density of 58 persons/km2, the population
affected by a severity of 0.1 is 11 people residing within 0.49
0.49 km from the plant boundary. The maximum source severities
for nitrogen oxides (NOX) and carbon monoxide (CO) from blasting
are 0.089 and 0.00017, respectively, with zero affected
population.
15
-------
SECTION 5
CONTROL TECHNOLOGY
STATE OF THE ART
Many plants control emissions from unpaved roads by frequently
spraying the roads with water or oil. Some plants use a wet
suppression system and/or baghouse to suppress dust emissions
from crushing, screening, and conveying operations.
Dust generated from various operations is dependent upon the dry-
ness of the handled material; hence, any method used to add mois-
ture is helpful in controlling dust levels. Natural phenomena
such as rain or snow and in-process washing or spraying opera-
tions are good examples of methods for controlling dust.
FUTURE CONSIDERATIONS
The fugitive and point sources of dust limestone processing are
drilling, blasting, loading, unpaved road transport, crushing,
screening, conveying, and stockpiling.
Dust emissions from dry percussion drilling operations can be con-
trolled by adding water or water mixed with a surfactant to the
air used for flushing drill cuttings from the hole. Dilution
ratios range from 800 to 3,000 parts of water to 1 part surfac-
tant. An 89-mm-diameter hole requires 0.026 m3/hr of solution.
This permits the drill cutting to be blown from the hole as damp,
dust-free pellets (11).
In conventional coal mining, water-filled plastic bags with or
without solid stemming material (clay) are used for stemming dust
emissions from blast holes. This method reduces dust concentra-
tions by 20% to 80% and explosive consumption by about 10% (12).
Instead of liquids, "thixotropic" cellulose or bentonite pastes
can be used. Such pastes are gelatinous in repose but liquefy
when disturbed. A similar control method may be applicable for
reducing particulate emissions from blasting in limestone mining.
(11) Jones, H. R. Fine Dust and Particulates Removal. Noyes
Data Corporation, Park Ridge, New Jersey, 1972. 307 pp.
(12) Grossmueck, G. Dust Control in Open Pit Mining and
Quarrying. Air Engineering, 10(25):21, 1968.
16
-------
Release of carbon monoxide, nitrogen oxides, and other gases such
as aldehydes and hydrogen can be curtailed by having a dry blast
hole and by properly carrying out the detonation to prevent
incomplete combustion.
Loading of the blasted limestone into trucks by front-end loaders
results in 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 load with a tarpaulin or wetting its
surface with water or water mixed with chemicals.
Water application is also an effective method for controlling
emissions from unpaved roads; however, approximately 5% to 8%
moisture (by weight) must be applied to suppress the dust
emissions (13). 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 chloride can be applied at a
cqst of approximately $0.15/m2 treated per year (14). The major
problems involved in its use are the corrosion of vehicle bodies
and leaching by rainwater or melting snow.
Another effective method of dust control is to mix stabilizing
chemicals into the road surface to a depth of approximately 20 mm
to 50 mm (15). One cement company uses a special emulsion agent3
and a treatment which involves spraying a solution of 4 parts of
water and 1 part of the emulsion agent at the rate of 0.009 m3/m2
of the road surface. Certain pretreatment measures such as
working the road surface into a stiff mud are necessary to pre-
vent the binder in this emulsion agent from sticking to the
vehicles. Periodic maintenance using a 1:7 emulsion agent/water
solution spray keeps the emulsion agent binder active. This dust
control program was found to give 3 yr of service at a total cost
of $0.12/m2.
aCoheren, supplied by Golden Bears Division, Wetco Chemicals
Company.
(13) Dust Suppression. Rock Products, 75:137, May 1972.
(14) Vandegrift, A.E., L. J. Shannon, P. G- Gorman, E. W. Law-
less, E. E. Sallee, and M. Reichel. Particulate Pollutant
Systems Study, Volume III: Handbook of Emission Properties,
Contract EPA-22-69-104, U.S. Environmental Protection
Agency, Durham, North Carolina, May 1971. 607 pp.
(15) Significant Operating Benefits Reported from Cement Quarry
Dust Control Programs. Pit and Quarry, 63(7):116, 1971.
17
-------
In some counties in Iowa, mixing cutback asphalt into the road
surface to a depth of 50 mm to 80 mm has been investigated (16).
This type of 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 effi-
cient method of controlling unpaved road dust emissions. The
cost for such applications is estimated to be $0.10/m2 treated
per year (11). However, a study conducted in New Jersey shows
that 70% to 75% of the oil applied moves to the surrounding
ecosystem from the surface of the road by dust transport and
runoff. The oil or its heavy metal constituents such as lead
may cause ecological harm (17). Furthermore, surface oiling
requires regular maintenance because roads treated in this
manner develop potholes.
Lignin sulfonates, byproducts from paper manufacture, are also
used to control dust emissions. A commercially available lignin
sulfonate9 was tested on a farm access road at Arizona State
University (18). The method proved quite successful, giving 5 yr
of service and effective dust suppression at a cost of $0.47/m2
for 5 yr ($0.10/m2-yr).
Paving the road surface is the best method for controlling dusts,
but it is impractical due to its high cost and the temporary
nature of crushed limestone 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. A crushed rock
production plant uses a dust suppression system^ and a chemical
wetting agent. Approximately 0.004 m3 of the concentrated wet-
ting 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
Orzan A., supplied by Crown-Zellerback Corporation.
Chem-Jet, supplied by Johnson-March Corporation.
(16) Hoover, J. M. Surface Improvement and Dust Palliation of
Unpaved Secondary Roads and Streets. ERI Project 856-S,
Iowa State Highway Commission, Des Moines, Iowa, July 1973.
97 pp.
(17) Freestone, F. J. Runoff of Oils from Rural Roads Treated
to Suppress Dust. EPA R2-72-054, U.S. Environmental Protec-
tion Agency, Cincinnati, Ohio, October 1972. 29 pp.
(18) Bub, R. E. Air Pollution Alleviation by Suppression of
Road Dust. M.S.E. Thesis, Arizona State University, Tempe,
Arizona, June 1968. 45 pp.
18
-------
reducing dust emissions at transfer points, screening operations,
storage bins, and stockpiling operations (19). Such a system has
many cost-saving advantages. It requires no ducts, hoods, or
other enclosures for crushers, screens, or conveyors. The
equipment is in the open and allows the operators to see the
entire material flow. Dust is not collected, and there are no
solid waste disposal or water pollution problems.
In a crushed stone plant (with processes similar to those of a
crushed limestone plant), a baghouse is used to control dust
emissions from cone crushers, scalping screens, and twin sizing
screens, and at the shuttle and transfer conveyors. The range of
dust collected is 2,722 kg to 5,443 kg in a 10-hr day from a 182-
metric ton/hr plant (20) . A baghouse does not provide for dust
control in stockpile areas unless these areas are totally
enclosed.
The dust collected in the baghouse presents a solid waste prob-
lem. The alternative disposal methods are to put the dust into
settling basins or to develop sales opportunities. Depending on
the type of material and the local market conditions, uses may
include manufactured sand, underslab fill, and asphalt filler
(21).
(19) Harger, H. L. Methods Used by Transit Mix Operators to Meet
Air Pollution Control District Requirements. National Sand
and Gravel Association and National Ready Mixed Concrete
Association, Washington, D.C., April 1971. 22 pp.
(20) Trauffer, W. E. Maine's New Dust-Free Crushed Stone Plant.
Pit and Quarry, 63 (2):96, 1970,
(21) Ozol, M. A., S. R.,Lockete, J. Gray, R. E. Jackson, and
A. Preis. Study to Determine the Feasibility of an Experi-
ment to Transfer Technology to the Crushed Stone Industry.
Contract NSF-C826, National Science Foundation, June 1974.
50 pp.
19
-------
SECTION 6
GROWTH AND NATURE OF THE INDUSTRY
PRESENT TECHNOLOGY
Present technological improvements include the use of larger and
more efficient crushing and screening plants. Primary crushing
is often done near the pit with jaw or impact crushers. Second-
ary crushing is done by cone crushers or impact crushers. The
crushed limestone is screened and sent to open area storage.
EMERGING TECHNOLOGY
This study did not reveal emerging technology of specific impor-
tance to air pollution control in the crushed limestone industry.
PRODUCTION TRENDS
Production of crushed limestone is tied closely to the product
consuming industries. Since the construction industry consumes
more than 67% of the output, the production of crushed limestone
is associated chiefly with the needs of this industry (3). Pro-
duction of crushed limestone was 6.1 x 108 metric tons in 1972.
In 1973, 7.0 x 108 metric tons and in 1974, 6.;8 x 108 metric tons
of crushed limestone were either shipped to or used by producers
in the United States (22).
Assuming the same annual growth rate as that for the crushed
stone industry (3.5% to 5.1%), the contingency forecast of
crushed limestone demand in the year 2000 is 1,200 to 2,000 x 106
metric tons.
Transportation constitutes a major part of the delivered cost of
crushed limestone. These costs may exceed the sales value of the
material at the processing plants, which are therefore located
near the point of use. Local zoning and environmental regula-
tions and depletion of urban deposits may necessitate the loca-
tion of future plants much farther from the point of use. This
should increase the use of rail and barge systems to hold down
transportation costs. Truck haulage will remain important,
(22) Mineral Industry Surveys. Annual Advance Summary. U.S.
Department of the Interior, Washington, D.C., September 17,
1975. 12 pp.
20
-------
especially for local delivery of crushed products, despite the
use of rail and water transportation for long distances to
central distribution points. These factors will undoubtedly
result in an increase in the delivered price of crushed
limestone.
21
-------
REFERENCES
1. Kirk-Othmer Encyclopedia of Chemical Technology, Second
Edition, Vol. 12. John Wiley & Sons, Inc., New York, New
York, 1969. pp. 414-423.
2. 1972 Census of Mineral Industries, Subject Series: General
Summary. MIC 72(1)-1, U.S. Department of Commerce,
Washington, D.C., 1975. 174 pp.
3. Mineral Industry Surveys. U.S. Department of the Interior,
Washington, D.C., 1972. 12 pp.
4. Sax, N. J. Dangerous Properties of Industrial Materials,
Third Edition. Reinhold Book Corporation, New York, New
York, 1968. pp. 1088-1089.
5. TLVs® Threshold Limit Values for Chemical Substances and
Physical Agents in the Workroom Environment with Intended
Changes for 1976. American Conference of Governmental
Industrial Hygienists, Cincinnati, Ohio, 1976. p. 32.
6. Blackwood, T. R., P. K. Chalekode, and R. A. Wachter.
Source Assessment: Crushed Stone. Contract 68-02-1874,
U.S. Environmental Protection Agency, Cincinnati, Ohio, July
1977. 91 pp.
7. 1972 National Emissions Report. EPA-450/2-74-012, U.S.
Environmental Protection Agency, Research Triangle Park,
North Carolina, June 1974. 422 pp.
8. Turner, D. B. Workbook of Atmospheric Dispersion Estimates.
Public Health Service Publication No. 999-AP-26, U.S.
Department of Health, Education, and Welfare, Cincinnati,
Ohio, May 1970. 84 pp.
9. Nonhebel, G- Recommendations on Heights for New Industrial
Chimneys. Journal of the Institute of Fuel, 33:479, 1960.
10. Blackwood, T. R., and R. A. Wachter. Source Assessment:
Coal Storage Piles. Contract 68-02-1874, U.S. Environmental
Protection Agency, Cincinnati, Ohio, July 1977. 96 pp.
11. Jones, H. R. Fine Dust and Particulates Removal. Noyes
Data Corporation, Park Ridge, New Jersey, 1972. 307 pp.
22
-------
12. Grossmueck, G. Dust Control in Open Pit Mining and Quarry-
ing. Air Engineering, 10(25):21, 1968.
13. Dust Suppression. Rock Products, 75:137, May 1972.
14. Vandegrift, A. E., L. J. Shannon, P. G. Gorman, E. W. Law-
less, E. E. Bailee, and M. Reichel. Particulate Pollutant
Systems Study, Volume III: Handbook of Emission Properties.
Contract CPA-22-69-104, U.S. Environmental Protection Agency,
Durham, North Carolina, May 1971. 607 pp.
15. Significant Operating Benefits Reported from Cement Quarry
Dust Control Programs. Pit and Quarry, 63(7):116, 1971.
16. Hoover, J. M. Surface Improvement and Dust Palliation of
Unpaved Secondary Roads and Streets. ERI Project 856-S,
Iowa State Highway Commission, Des Moines, Iowa, July 1973.
97 pp.
17. Freestone, F. J. Runoff of Oils from Rural Roads Treated to
Suppress Dust. EPA R2-72-054, U.S. Environmental Protection
Agency, Cincinnati, Ohio, October 1972. 29 pp.
18. Bub, R. E. Air Pollution Alleviation by Suppression of Road
Dust. M.S.E. thesis, Arizona State University, Tempe,
Arizona, June 1968. 45 pp.
19. Harger, H. L. Methods Used by Transit Mix Operators to Meet
Air Pollution Control District Requirements. National Sand
and Gravel Association and National Ready Mixed Concrete
Association, Washington, D.C., April 1971. 22 pp.
20. Trauffer, W. E. Maine's New Dust-Free Crushed Stone Plant.
Pit and Quarry, 63(2):96, 1970.
21. Ozol, M. A., S. R. Lockete, J. Gray, R. E. Jackson, and A.
Preis. Study to Determine the Feasibility of an Experiment
to Transfer Technology to the Crushed Stone Industry.
Contract NSF-C826, National Science Foundation, June 1974.
50 pp.
22. Mineral Industry Surveys. Annual Advance Summary. U.S.
Department of the Interior, Washington, D.C., September 17,
1975. 12 pp.
23. Chaiken, R. F., E. B. Cook, and T. C. Ruhe. Toxic Fumes
from Explosives. Ammonium Nitrate-Fuel Oil Mixtures.
Bureau of Mines RI-7867 (PB 233 496), U.S. Department of the
Interior, Washington, D.C., May 1974. 29 pp.
23
-------
24. J. C. Ochsner, P. K. Chalekode, and T. R. Blackwood. Source
Assessment: Transport of Sand and Gravel. Contract 68-02-
1874, U.S. Environmental Protection Agency, Cincinnati,
Ohio, October 1977. 63 pp.
25. Cheng, L. Formation of Airborne-Respirable Dust at Belt
Conveyor Transfer Points. American Industrial Hygiene
Association Journal, 34(12):540-546, 1973.
26. Cowherd, C. Development of Emission Factor for Fugitive
Dust Sources. EPA-450/3-74-037, U.S. Environmental Protec-
tion Agency, Research Triangle Park, North Carolina, June
1974. 172 pp.
27. Blackwood, T. R., R. 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.
28. Andresen, W. V. Industrial Hygiene Design in Raw Materials
Handling Systems. American Industrial Hygiene Association
Journal, 23 (6):509-513, 1962.
29. Lilienfeld, P., and J. Dulchinos. Portable Instantaneous
Mass Monitor for Coal Mine Dust. American Industrial
Hygiene Association Journal, 33(3):136, 1972.
30. Eimutis, E. C., and M. G. Konicek. Derivations of Continu-
ous Functions of the Lateral and Vertical Atmospheric Disper-
sion Coefficients. Atmospheric Environment, 6 (11) :859-863,
1972.
31. Gifford, F. A., Jr. An Outline of Theories of Diffusion in
the Lower Layers of the Atmosphere. In: Meteorology and
Atomic Energy 1968, Chapter 3, D. A. Slade, ed. Publication
No. TID-24190, U.S. Atomic Energy Commission Technical
Information Center, Oak Ridge, Tennessee, July 1968. pp.
65-116.
32. 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, Minne-
sota, June 23-27, 1968. 18 pp.
24
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APPENDIX A
LITERATURE SURVEY
A study was made to predict and analyze those parameters affect-
ing dust emissions from the seven handling operations in crushed
limestone processing:
• Drilling and blasting
• Transport
• Conveying
« Unloading
• Open storage
• Loading
• Crushing/grinding/sizing
There were two major classifications of parameters: t,
dependent on the material and those dependent on the ope. ion.
Material-dependent parameters, generally the same for all o; ••-
ations, are moisture content, density, and "dustiness index,
which will be defined as the mass of respirable dust adhering CL
2.2 kg of material. Density delineates differences in particle
size distribution between different samples of the same material.
The "dustiness index" is used to determine differences in emis-
sions from different materials undergoing the same operation.
Parameters dependent on the operation are as varied as the opera-
tions themselves.
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
The literature search neither yielded quantitative data nor indi-
cated a relationship between the emission factor (ED) and the
25
-------
aforementioned factors. A qualitative relationship might possi-
bly resemble
(1)(3) , ,;
ED a (2) (4) (5) (A ±}
where the numbers in parentheses represent functions of the
respective variables shown above.
Of all the unit operations, dust emissions from blasting have
been studied the least. The literature search yielded a poten-
tial list of factors influencing emissions: frequency of blast-f
ing, bulk moisture content of the rock, particle size distribu-
tion, type and amount of explosive, and hole size.
Studies have been conducted on the magnitude of gaseous emissions
of nitrogen oxides and carbon monoxide from blasting. Stoichio-
metric ratios of ammonium nitrate-fuel oil (ANFO) mixtures (5.5%
fuel oil) should not produce nitrogen oxide and carbon monoxide
emissions. Theoretically, a higher percentage of fuel oil should
not give nitrogen oxides and should yield more carbon monoxide
than carbon dioxide. Conversely, a lower percentage of fuel oil
should not produce carbon monoxide and should give more nitrogen
oxides than nitrogen.
Experimental investigations by the Bureau of Mines (23) show that
4% fuel oil results in 1.3 m3 (at standard conditions) of NOX per
kilogram of ANFO and 1.3 m3 of CO per kilogram of ANFO, while 6%
fuel oil results in 0.32 m3 of NOx per kilogram of ANFO and 1.8 m3
of CO per kilogram of ANFO. The maximum emission factor figures
have been used for the severity calculations.
TRANSPORT OPERATIONS
Transport operations are discussed in detail in another assess-
ment document (24).
CONVEYING OPERATIONS
Dust emissions from conveying operations come from wind-blown
dust during open conveying and conveyor discharge.
(23) Chaiken, R. F., E. B, Cook, and T. C. Ruhe. Toxic Fumes
from Explosives. Ammonium Nitrate-Fuel Oil Mixtures.
Bureau of Mines RI-7867 (PB 233 496), U.S. Department of the.
Interior, Washington, D.C., May 1974. 29 pp.
i, '
(24) J. C. Ochsner, P. K. Chalekode, and T. R. Blackwood. Source
Assessment: Trnasport of Sand and Gravel. Contract 68-02-
1874, U.S. Environmental Protection Agency, Cincinnati, Ohio,
October 1977. 63 pp.
26
-------
Emissions from conveyor discharge and parameters affecting these
emissions were evaluated by Cheng (25). The material 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:
R= 8'5° X
where R = specific formation of airborne respirable dust, g
_A = cross-sectional area of the falling granules, cm
PC = material density of the coal, g/cm*
G = gravitational acceleration, 980 cm/s2
H = height of fall, cm
M = belt load, g/cm2
B = width of the conveyor belt, cm
UR - linear speed of the conveyor belt, cm/s
Cheng concluded the following:
• About 10% of the adhering respirable dust becomes air-
borne by the impact of dropping.
• Reduction of the height of material fall reduces the
formation of airborne respirable dust.
• For heavy belt loads (coal bed thickness much greater
than mean lump size) , an increase in the thickness of
the coal bed reduces the specific formation of airborne
respirable dust.
UNLOADING OPERATIONS
Emissions from unloading operations are produced by dropping
materials from conveying machinery onto storage piles. A recent
study (26) showed that the emission factor, E, for unloading
operations, based on milligrams of suspended dust particles less
than 30 ym in diameter per kilogram of aggregate unloaded, obeyed
the following relationship:
_ 20 mg of particulate ra-^
kg of aggregate (A J)
(25) Cheng, L. Formation of Airborne-Respirable Dust at Belt
Conveyor Transfer Points. American Industrial Hygiene
Association Journal, 34 (12):540-546, 1973.
(26.) Cowherd, C. Development of Emission Factor for Fugitive
Dust Sources. EPA-450/3-74-037, U.S. Environmental Protec-
tion Agency, Research Triangle Park, North Carolina,
June 1974. 172 pp. :
27
-------
This emission factor was based on high-volume sampling at a sand
and gravel plant in the Cincinnati area. E was 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 unload-
ing operations, see Appendix A, "Conveying Operations." Although
the relationships derived for emissions from conveyor discharge
are based on coal conveyance, only a correction factor for the
relative dustiness of the material handled needs to be applied to
make the equation applicable to all conveying and unloading
operations.
OPEN STORAGE
Emissions due to open storage have been discussed in detail in
previous documents (10, 26, 27).
LOADING OPERATIONS
Emissions from loading operations occur in the transfer of mater-
ial from storage to transporting vehicles. For aggregates, this
transfer is accomplished by power shovels or front-end loaders
scooping the material from open storage piles and dumping it into
transporting vehicles, usually trucks. Dust arises from the
scooping and dropping processes.
Emissions from dropping are determined by many of the same para-
meters 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
An equation determining the amount of respirable dust, R, formed
by power shovel discharge, based on an equation for conveyor dis-
charge, should be of the form
(27) 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.
28
-------
R 0 (D(3)(6) (A_4)
K tt (2) (4) (5) (A 4;
where each number in parentheses represents a function of its
respective parameter as listed above.
Dust emissions from scooping operations are more difficult to
define because relevant information was not available. However,
the following factors are believed to play a large part in deter-
mining 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, R, a qualitative
relationship might possibly resemble
(7) (9) (10) , 5)
R a (8) (A b)
where each number in parentheses represents a function of its
respective parameter as shown above.
Although not applicable to the determination of R, it has been
found (25) that the emission factor, E, which can be expressed as
milligrams of dust less than 30 ym in diameter emitted per kilo-
gram of material loaded for loading crushed limestone at an
asphalt plant is represented by
? - 25 mg of dust .
kg of material loaded
E was believed to vary with the P-E Index of the area considered.
CRUSHING/GRIND ING/SIZING OPERATIONS
Emissions from crushing, grinding, and sizing operations are the
result of respirable dust formation during size reduction and
crusher or screen discharge.
The factors affecting discharge emissions are the same as those
for conveyor and power shovel discharge (see "Conveying Opera-
tions" and "Loading Operations" sections) .
Dust emissions from size reduction are judged to be influenced
by
29
-------
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 (3) (A_7)
R a (2) (4) (A 7)
where each number in parentheses is some function of the respec-
tive parameter listed above.
An induced air flow must be present for atmospheric dispersion of
the respirable dust. For most crushers, which operate at a
relatively low speed, air flow is induced only during discharge.
(See "Conveying Operations" section for a quantitative evaluation
of air flow induced by discharge.)
High-speed pulverizers create air flow during both size reduction
and discharge. Air flow induced by high-speed size reduction may
be inferred from the literature to be inversely proportional to
the rate of material flow through the size reducer (28) .
(28) Andresen, W. V. Industrial Hygiene Design in Raw Materials
Handling Systems. American Industrial Hygiene Association
Journal, 23 (6):509-513, 1962.
30
-------
APPENDIX B
SAMPLING DETAILS AND RESULTS3
SAMPLING SITE DESCRIPTION
The purpose of the sampling was to obtain data on the overall
plant emissions and the relative contributions of the various
unit operations.
Two crushed limestone plants were chosen whose operations were
.representative of the crushed limestone industry. In addition,
these plants were located in areas with favorable meteorological
conditions for sampling.
Plant A
Mining—
At the blasting site, holes are drilled in the rock in a circular
pattern and then charged with ANFO and dynamite. Blasting is
carried out 12 times per month at this mine. The yield is 2,700
metric tons of limestone rock per shot. The rock is loaded into
20-metric ton haul trucks by a front-end loader and transported
on an unpaved road to a primary crusher and a scalping screen.
Process Plant--
The scalping screen is a 1.22 m x 1.83 m vibrating screen, and
it separates material less than 80 mm in size. The oversized
material is fed to a Cedar Rapids 4350S double impeller impact
crusher which crushes the feed to less than 80 mm size. Under-
sized material from the scalping screen and crushed material from
the primary crusher are conveyed to screens arranged in series.
The first screen is a 1.22 m x 3.66 m, two-deck screen that
separates the material into three sizes: greater than 64 mm,
44 mm to 64 mm, ai^ less than 44 mm. The oversized material from
the screen may be stockpiled or crushed again in a Universal
impact crusher and reconveyed to the screen.
The undersized material from the first screen goes to a 1.22 m x
4.27 m, three-deck horizontal screen that separates the feed into
three sizes: 19 mm to 44 mm, 6 mm to 19 mm, and less than 6 mm.
aNonmetric units appear in this appendix because they were used
in the original work.
31
-------
The products are stored in bins or stockpiles and loaded, into
trucks for shipment to customers.
The plant operates for 8 hr/day and the average processing rate
through the primary crusher is 190 metric tons/hr. The number of
days of operation in a year depends on both the demand for the
product and the functioning of the equipment—usually about 6 mo
to 8 mo/yr at 5 days/wk.
Plant B
Mining—
The mining activities are similar to those at plant A.
Process Plant—
The scalping screen is a 1.22 m x 2.44 m vibrating screen which
separates material less than 100 mm in size. The oversized
material is fed to a 1.07 m x 1.22 m Lippman jaw crusher which
crushes the feed to less than 100 mm size. The undersized mater-
ial from the scalping screen and the crushed material from the
primary crusher are conveyed to a 1.52 m x 3.66 m horizontal
screen. This screen separates the material into less than 50-mm
and greater than 50-mm particles. The oversized material
(greater than 50 mm) goes through two shorthead cone crushers.
The undersized (less than 50 mm) material and the material from
the cone crushers are conveyed to a 1.83 m x 4.88 m, three-deck
horizontal screen. This screen separates the material into three
different sizes: 19 mm to 50 mm, 13 mm to 19 mm, and less than
13 mm. The products are stored in bins or stockpiles prior to
shipment.
The plant operates for 8 hr/day and the average processing rate
through the primary crusher is 330 metric tons/hr. The plant
operates for 8 mo/yr at 5 days/wk.
Both plants A and B control emissions from unpaved roads by
spraying the roads with oil. Sampling data and results are given
later in Tables B-4, B-5, and B-6.
SAMPLING PROCEDURES
Samplers
General Metal Works high-volume samplers8 were positioned around
an area as shown in Figure B-l. For this arrangement, the origin
was defined at the source, and all remaining points were defined
in the Cartesian coordinate system. The angle of mean wind
direction was 6. The downwind distance of any point y. perpendi-
cular to the wind direction centerline was computed in1the follow-
ing manner:
9General Metal "'Works, Inc., 8368 Bridgetown Road, Cleveland, Ohio
45002.
32
-------
WIND AZIMUTH
METEOROLOGICAL STATION
Figure B-l. Sampling arrangement
mj ='tan 8
and for point S. with coordinates x., y.,
(B-l)
m? = —
z x.
The angle a was found from
a - arctan
1 +
The lateral distance Y. is
(B-2)
(B-3)
. = (sin a)
(B-4)
and the downwind distance X. is
X. = (cos a) /xi2 + y±2 (B-5)
These values are used in appropriate dispersion models. The
sampling time for high-volume samplers was about 4 hr. Five
different high-volume samplers were used to monitor the area
emissions at positions S0, S^, 82/ S3, and S^.
33
-------
A GCA respirable dust monitor was used to obtain downwind con-
centrations of respirable and total particulates from unit opera-
tions (29). The sampling time for the GCA instrument was about
4 min; hence, only one unit was necessary to monitor at all the
positions (not simultaneously).
The high-volume samplers collect particles less than 100 ym in
size, while the GCA unit collects less than 10-ym particles with
a cyclone separator and less than 50-ym particles without a
cyclone separator.
Models
Open source sampling uses diffusion models in reverse. It is
used to predict concentrations surrounding a point source of
known strength. Several concentration readings are taken to
calculate the source strength of an open source.
Models applicable to the sampling arrangement and source char-
acteristics are chosen and utilized for each emissive source.
Three models are used in this study. The first represents emis-
sions from drilling, front-end loading, primary and secondary
crushing, and secondary screening. This is the point source
model (8) where
X (x, y, z; H) =
exp
exp
(B-6)
z - H
exp
z + H
The notation used to depict the concentration is x (x/ Y/ z; H).
H, the height of the plume centerline from the ground level when
it becomes essentially level, is the sum of the physical stack
height, h, and the plume rise, AH. The following assumptions are
made: the plume spread has a Gaussian distribution in both the
horizontal and vertical planes, with standard deviations of plume
concentration distribution in the horizontal and vertical of a
and az/ respectively; the mean wind speed affecting the plume Is
u; the uniform emission rate of pollutants is Q; and total reflec-
tion of the plume takes place at the earth's surface; i.e.,
there is no deposition or reaction at the surface. Any consist-
ent set of units may be used. The most common is x J-n grams per
cubic meter; Q in grams per second;, u in meters per second; and
GCA Corporation, GCA Technology Division, Bedford, Massachusetts,
(29) Lilienfeld, P., and J. Dulchinos. Portable Instantaneous
Mass Monitor for Coal Mine Dust. American Industrial
Hygiene Association Journal, 33(3):136, 1972.
34
-------
tfy, az, H, x, y, and z in meters. The concentration x is a mean
over the same time interval as the time interval for which the
a's and u are representative. The values of both ay and az are
evaluated in terms of the downwind distance, x, and stability
class. Stability classes are determined conveniently by graphi-
cal methods, Figure B-2 (27) . Continuous functions are then used
to calculate values for ay and az, Tables B-l and B-2, given the
downwind distance, x (30) . In open source sampling, the sampler
is maintained in the center of the plume at a constant distance;
the plume has no effective height (H equals 0) ; and the concentra-
tions are calculated at ground level. Equation B-6 thus reduces
to (8)
* <*' °' °<- °> = - (B~7)
y z
The second model is used to describe emissions from belt convey-
ing and transporting on unpaved roads. In this equation, instan-
taneous puff concentrations are described by Equation B-8 (31) :
/ ? \ 1/2 Qn
$ = £ ' — °_ (B-8)
U } azlu
where if/ = dose, g-s/m3
QD = line source emissions per length of line, g/m
azl = instantaneous vertical dispersion parameter, m
u = mean wind speed, m/s
For neutral stability,
azl = 0.15 xc°-7 (B-9)
where x = crosswind distance from the line source, m
IM>
Equation B-8 is a line source diffusion model and is used to find
the mass emissions per length of road or per length of conveyor
belt. The value of the dose, fy, is determined by multiplying the
concentration by the actual sampling time.
The third model is used in computing total dose from a finite
release in blasting. This is calculated from Equation B-10 (8):
(30) Eimutis, E. C., and M. G. Konicek. Derivations of Continuous
' Functions of the Lateral and Vertical Atmospheric Dispersion
Coefficients. Atmospheric Environment, 6(11):859-863, 1972.
(31) Gifford, F. A., Jr. An Outline of Theories of Diffusion in
the Lower Layers of the Atmosphere. In: Meteorology and
Atomic Energy 1968, Chapter 3, D- A. Slade, ed. Publication
No. TID-24190, U.S. Atomic Energy Commission Technical Infor-
mation Center, Oak Ridge, Tennessee, July 1968. pp. 65-116.
35
-------
CO
en
START
ATMOSPHERIC
CLASS ISO
CD
RADIATION INDEX = - 2
I NO
RADIATION INDEX -
-1
1
TIME OF DAY
INSOLATION
CLASS
NOONTIME
LATE AM, EARLY PM
Ml DAM, MIDPM
EARLY AM, LATE PM
4
3
2
1
Figure B-2. Flow chart of atmospheric stability class determination.
-------
TABLE B-2.
VALUES OF a FOR THE COMPUTATION OF o (30)
Stability class
A
B
C
D
E
F
a
0.3658
0.2751
0.2089
0.1471
0.1046
0.0722
For the equation
ay = axb
where x = downwind distance
b = 0.9031
TABLE B-3. VALUES OF THE CONSTANTS USED TO
ESTIMATE VERTICAL DISPERSION (32)
Usable range, Stability
m class Coefficient
>1,000 A
B
C
D
E
F
100 to 1,000 A
B
C
D
E
F
<100 A
B
C
D
E
F
0.00024
0.055
0.113
1.26
6.73
18.05
C2
0.0015
0.028
0.113
0.222
0.211
0.086
0.192
0.156
0.116
0.079
0.063
0.053
2.094
1.098
0.911
0.516
0.305
0.18
d2
1.941
1.149
0.911
0.725
0.678
0.74
0.936
0.922
0.905
0.881
0.871
0.814
-9.6
2.0
0.0
-13
-34
-48.6
fa
9.27
3.3
0.0
-1.7
-1.3
-0.35
0
0
0
0
0
0
For the equation
0 =
cxd + f
(32) Martin, D. O., 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, Minne-
sota, June 23-27, 1968. 18 pp.
37
-------
The parameters of Equation B-10 use the same units as Equation
B-6, except Qm is the total release in grams from the source and
DT is the total dose, grams per second per cubic meter. Again,
the dose is the product of the concentration and sampling time.
Equation B-10 is therefore termed a dose model.
Data Collection
Each variable for these models was determined in the field at
meteorological stations. A stationary meteorology station was
used for high-volume sampling. Wind speeds were averaged every
minute with a mean recorded for each 15-min interval. The mean
wind speed was calculated from the average of the 15-min record-
ings over the entire run. The samplers were therefore maintained
within the plume during sampling. The wind direction variation
was less than 0-785 rad from the centerline during the samplings.
The concentration at sampler Sg was subtracted from the concen-
trations at Si, S2, S3, and S^ to yield those due to the source
emissions. Mass emission rate was then calculated as an average
of the calculations done for N sampler readings using the appro-
priate dispersion equation.
The respirable dust monitor was mounted on the portable meteoro-
logical station shown in Figure B-3.
For each monitor concentration reading, displayed by direct
digital readout, the mean wind speed was determined by averaging
15-s readings (a stopwatch was used) of the wind meter. This
meter is connected to the anemometer which sits atop a 3.05-m
pole. Distance x was approximated by pacing over the rough
terrain.
These data were recorded for each sampling run on the form shown
in Figure B-4 while in the field. The time of day and atmos-
pheric stability (determined following Figure B-2) were recorded
periodically on the bottom of the form.
The terms used on the field data form are explained in Table B-3.
Any factors that might have affected concentration or emission
rate were mentioned in the column labeled "Comments." When this
form was completed, data were programmed into a computer and
emission rate, Q, was calculated in accordance with the model
specified in the column labeled "M."
38
-------
\
ANEMOMETER
CLIPBOARD.^
WIND METER
WEATHER POLE
T— ANEMOMETER
HOUSING
3| CYCLONE SEPARATOR
RESPIRABLEDUST
MONITOR
SAMPLING PLATFORM
STOPWATCH
TRIPOD STAND
Figure B-3. Sampling apparatus.
TABLE B-3. EXPLANATION OF FIELD DATA FORM TERMS
Term
Meaning
Read., mg/m3
Cone., yg/m3
R/T
BCD, yg/m3
A, yg/m3
Q, g or g/s
S1
M
Concentration reading.
Converted concentration for sampling
times greater than 4 min (lower
right-hand corner).
R = respirable reading;
T = total mass reading.
Background concentration.
Difference between converted concen-
tration and background.
Calculated emission rate.
Stability for time of day unit oper-
ation was sampled.
Model used referenced as 1, 2, or 3
(point, line, or dose,
respectively).
39
-------
MODEL: POINT - 1
LINE =2
SOURCE TYPE
DATE
BY _
O
UNIT OPERATION
TIME OF DAY
• T* t ff A n B i t TV/
ATM. STABILITY
WIND
SPEED
MPH
M^^^HB**
^ imimi I ' rim
DIS1
X
FANC
Y
E, FT
TIME
MIN.
READ.
mg/m3
CONC.
. — — .
R/T
BCD
,&3
Q,
9
TOTAL SAMPLING TIME
4 MINUTES
8 MINUTES
16 MINUTES
20 MINUTES
30 MINUTES
37 MINUTES
S1
M
COMMENTS
MULTIPLY READING BY
1
0.46
0.23
0.184
0.122
0.1
Figure B-4. Field data form.
-------
EMISSION LEVELS
The parameters in Equation B-6 were measured in the field in
order to obtain the emission rates (Q) per unit operation. These
data were recorded on the form shown in Figure B-4 and printed
out via computer in Tables B-4 and B-5 where the value of Q from
the appropriate dispersion model is automatically computed.
Using the site data presented in Section 1 of this appendix,
emission factors were computed as described below.
Blasting
From Table B-4, 36.29 g of respirable dust were emitted per shot
from which 2,720 metric tons of limestone were collected and
processed. Thus, the emission factor is
2,720 Metric tons = °-013 9/metric ton
Drilling
From Table B-4, the average respirable emission rate was
2.06 x 10~4 g/s per drill. Forty hours of drilling were required
for the shot of 2,720 metric tons. Thus, the emission factor is
2.06 x 10"tt (3,600) (40) n nn / ^ • ^
- 2 yon - - = 0-011 g/metric ton
Front-End Loading at Quarry
From Table B-4, an average of 1.23 x 10~k g/s of total particu-
lates was emitted for the 4 min of sampling. Thus, 0.030 g was
emitted in the filling of the 20-metric ton truck. Thus, the
emission factor is 1.5 x 10" 3 g/metric ton.
Primary Crushing
From Table B-4, 2.966 x 10~2 g/s of total particulate and
8.776 x 10~3 g/s of respirable particles are emitted while proc-
essing 190 metric tons. Thus, the emission factors are 562 and
166 mg/metric ton, respectively. Primary screening is calculated
in the same manner.
Secondary Crushing
From Table B-5, 1.323 x 10~2 g/s of total particulate and an
average of 7.02 x 10~3 g/s of respirable particulate are emitted
while processing 330 metric tons. Thus, the emission factors are
140 and 77 mg/metric tons, respectively. Secondary screening is
calculated in the same manner.
41
-------
TABLE B-4. SAMPLING DATA AND RESULTS (RESPIRABLE PARTICULATES)
CRUSHED LIMESTONE - PLANT A
Unit operation
Blasting
Drilling
Drilling
Front- end loading"
Primary crushing
Primary crushing"
Primary screening
U
13.5
7.0
5.0
3.0
3.0
3.0
3.0
X
400.0
10.0
10.0
20.0
50.0
50.0
20.0
Y
0.0
0.0
0.0
0.0
10.0
10.0
0.0
Z
0.0
0.0
0.0
0.0
0.0
0.0
0.0
Time
9.0
4.0
4.0
4.0
4.0
4.0
4.0
CHI
57.0
130.0
510.0
100.0
290.0
980.0
20.0
3.
1.
3.
1.
8.
2.
2.
Q
629 x
085 x
039 x
231 x
776 x
966 x
463 x
101
10-"
10-*
10-*
io-3
ID"2
ID'5
Units
g
g/s
g/S
g/s
g/s
g/s
g/s
s
D
D
D
D
D
D
D
TABLE B-5. SAMPLING DATA AND RESULTS
CRUSHED LIMESTONE - PLANT B
KJ
Unit operation U
Secondary crushing 3 . 0
Secondary crushing 3.0
Secondary crushing15 3.0
Belt conveyors 3.0
Secondary screening 2.0
Secondary screening 2.0
Unpaved road 2 . 0
Unpaved road 2 . 0
Unpaved road - 2.0
X
60.
60.
60.
50.
30.
30.
70.
30.
30.
0
0
0
0
0
0
0
0
0
Y
10.
10.
10.
0.
0.
0.
0.
0.
0.
0
0
0
0
0
0
0
0
0
Z
0.
0.
0.
0.
0.
0.
0.
0.
0.
Time
0
0
0
0
0
0
0
0
0
4
4
4
4
4
4
4
8
4
.0
.0
.0
.0
.0
.0
.0
.0
.0
CHI Q
120.0 3.239 x 10~3
400.0 1.080 x 10"2
490.0 1.323 x ID'2
100.0 1.463 x 10-*
40.0 6.769 x 10"5
10.0 1.692 x 10~5
80.0 1.050 x 10"*
55.2 3.433 x 10"5
30.0 1.866 x 10"s
Units
g/s
g/s
g/s
g/m-s
g/s
g/s
g/m-s
g/m-s
g/m-s
S
D
D
D
D
D
D
D
D
D
U = wind speed, mph;
X = distance downwind, ft;
Y = distance from plume
Z = elevation of source
center
, ft
discharge,
*
1
ft
*
/
.-
Time
CHI
S
= sample time, min;
= measured concentration
less background,
= stability class.
pg/m3 ;
Total particulate measurement.
-------
Belt Conveyors
From Table B-5, 1.463 x KT1* g/s of respirable particles is
emitted per meter of belt. Since the total length of belt was
60 m in this plant, the emission factor is
1.46 x 10-^ g/m-s (3,600 s/hr) (60 m) n nnr ,
' 330 metric tons/hr - = °-096 g/metric ton
Vehicular Traffic on Unpaved Roads
From Table B-5, the three emission factors in grams per meter-
second are converted to grams per vehicle-meter (v-m) as follows
1.05 x 1Q-H g/m-s (240 s) _ .n .
- - (3 vehicles) - ~ = 8'40 m9/v-m
3.433 x 10~5 g/m-s (480 s) _ ._ ,
- (3 vehicles) - ~ = 5'49 m9/v-m
1.866 x 10~5 g/m-s (240 s) , ,_
- - = 4"48
for an average of 6.13 mg/v-m. Since each truck (vehicle) con-
tains 20 metric tons and travels an average of 750 ma , the emis-
sion factor becomes
<750 m) = 23° ^/^tric ton
6.13 mg/v-m 20
Respirable emissions from unpaved roads are about 18% of total
particulate emissions when roads are wet (6) . The roads were
oiled at these limestone plants; thus only about 10% of the emis
sions are estimated to be respirable.
The emission factors are listed in Table B-6 along with their
fractions of respirable particulates.
COMPOSITION
The emissions! from both of the plants were analyzed for free
silica. (For a description of the analysis methods and proce-
dures, see Reference 6.) Table B-7 presents the free silica
analysis from crushed limestone operations. The sample weight
was not enough to perform trace element analysis. The trace
element data provided in Table B-8 are those from previous
studies.
aThe average distance between quarry and process plant is about
750 meters for crushed stone operations (6).
43
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TABLE B-6.
PARTICULATE EMISSIONS FROM
CRUSHED LIMESTONE PLANT
Emission factor
Operation
Respirable
particulates,
g/metric ton
Total
particulates,
g/metric ton
Fraction of
respirable
particulates, %
Drilling
Blasting
Loading at the quarry
Vehicular traffic'3
Primary crushing
Primary screening
Secondary crushing
Secondary screening
Conveying
Wind erosion of stockpiles
Unloading at stockpiles
TOTAL
0.011
0.013
0
0.23
0.17
0.0005
0.077
0.0005
0.096
_e
~e
0.6
0.11
0.075
0.0015
2.3
0.56
0.0016
0.14
0.0009
0.32
_e
~e
3.5
a
10a
17
0
10
30c
30
53 .
53c
30
17
Estimated from drilling and blasting operations at crushed stone plants (6)
b
On paved road between quarry and plant.
Assumed same as primary crushing. Conveying was from the primary crusher.
Assumed same as secondary crushing.
a
"Negligible.
TABLE B-7. FREE SILICA ANALYSIS OF EMISSIONS
FROM CRUSHED LIMESTONE PLANT
Sample Free silica, %
1 1.2
2
Estimate of free silica
content.
44
-------
TABLE B-8.
TRACE ELEMENT ANALYSES OF LIMESTONE
IN WEIGHT PERCENT (1)
.
Indiana
high-
calcium
Element stone
Aluminum 0.42
Arsenic _a
Barium 0.001
Boron 0.00015
Bromine _a
Calcium
Carbon 0.49
Cesium a
Chlorine 0.0038
Chromium 0.0076
Cobalt
Copper a
Fluorine 0.0012
Gallium
Iron 0.25
Lead a
Lithium 0.00018
Magnesium >1
Manganese 0-0140
Molybdenum
Nickel
Nitrogen 0.00045
Phosphorus 0.0085
Potassium 0.058
Rubidium 0.00017
Silicon
Sodium 0.036
Strontium 0.15
Sulfur 0.022
Tin
JL JL i J.
Titanium 0.044
Vanadium 0.0015
Yttrium a
Zinc 0.0059
Note. — Blanks indicate
3 Not detected; numbers
element present.
Leigh
Valley, PA
cement
rock
0.33
0.0011
a
0.00008
a
0.00043
0.0019
a
0.00043
0.09
0.000031
0.4
0.015
0.00022
0.005
0.033
0.00007
0.17
0.22
0.003
0.016
0.00053
0.0006
Pennsylvania
cement rock
0.009
(<0.20)a
(<0.005)
39
0.001
(<0.002)
0
a
(<0.006)
0.07
(<0.01)a
0.3
0.025
(<0.002)a
a
(<0.5)
0.24 .
(<0.06)
0.039
a
(<0.008)
(<0.004)
a
(<0.06)
Illinois
Niagaran
dolomitic
stone
0.012
a
(<0.005)
35
0.00084
(<0.001)
0.00011
3
(<0.002)
o.io a
(<0 . 01)
2.9
OrfK •• <•
.011
0 ,
(<0.001)
(<0.20)a
0. 65
0.036
0.078
3
(<0.003)d
no reported data.
in parenthese
s indicate upper limit of
Trace.
45
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APPENDIX C
SOURCE SEVERITY AND AFFECTED POPULATION
TOTAL PARTICULATES
Source Severity
Maximum source severity for particulates from ground level
sources (6) is given as
S = -
D
l .814
where S = maximum source severity
Q = emission rate, g/s
D = representative distance from the major source, m
The emission rate for total particulates from the representative
plant is estimated as
Q = 450 metric tons/hr (3.50 g/metric ton) 1 hr/3,600 s
= 0.441 g/s
Substituting the values of Q and D into Equation C-l , the sever-
ity for respirable particulates is
S = (4. 020) (0.441) = 0
Affected Population
The affected population is defined as the population living
beyond the plant boundary where the source severity is 0.1 or
greater. Since the maximum severity is less than 0.1 at the
plant boundary, the affected population is zero.
FREE SILICA
Source Severity
Source severity for free silica emissions is given as (6)
46
-------
S - (C-2)
l .811*
where TLV is the threshold limit value for respirable dusts con-
taining free silica in grams per cubic meter, which is given as
= 3'125 x 10~3
% free slica + 2
The emission rate for respirable particulates from the represen-
tative plant is estimated as
Q = 450 metric tons/hr (0.60 g/metric ton) 1 hr/3,600 s
= 0.076 g/s
For free silica in respirable particulates,
s = _ (316) (0.076) _ =0.14
(410) l -8lk (3.125 x 10~3)
Affected Population
X = distance from source
I" (316) (0.076) I 1/1.81
[(S) (3.125 x 10~3) J
For S = 0.1, Xs=0 ± = 0.49 km
Since the distance of the plant boundaries is 0.26 km from the
major source, the affected area is
IT
(0.482 - 0.412) = 0.20 km2
For a representative population density of 58 persons/km2, the
affected population is 11 people.
NITROGEN OXIDES AND CARBON MONOXIDE
The source severity for nitrogen oxides is calculated from Equa-
tion C-3 (6):
= 22,200 Q (c_3)
bNOx Di.90
The emission rate for nitrogen oxides from the representative
plant is estimated as
Q = 450 metric tons/hr (2.85 g/metric ton) 1 hr/3,600 s
= 0.359 g/s
47
-------
Severity is thus 0.089 at 410 ra, and the affected population is
zero.
Severity for carbon monoxide is calculated from Equation C-4 (6)
_ 44.8 Q (
SCO ~ Di-81 ^
The carbon monoxide severity is thus 1.7 x 10"1* at 410 m, with
zero affected population.
48
-------
GLOSSARY
amorphous: Without stratification or other division;
uncrystallized.
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.
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.
dustiness index: Reference used in measuring the amount of
dust settled where a material is dropped in an enclosed
chamber.
emission burden: Ratio of the total annual emissions of a pol-
lutant from a specific source to the total annual state or
national emissions of that pollutant.
fibrosis: Growth of fibrous connective tissue in an organ in
excess of that naturally present.
free silica: Crystalline silica defined as silicon dioxide
(SiO2) arranged in a fixed pattern (as opposed to an
amorphous arrangement).
hazard factor: Measure of the toxicity of prolonged exposure
to a pollutant.
impact crusher: Lightweight crusher for breaking medium-to-
soft ores.
jaw crushers: Crushers that give a compression or squeeze
action between two surfaces.
limestone: Rock consisting mainly of calcium carbonate.
noncriteria pollutant: Pollutant for which ambient air quality
standards have not been established.
49
-------
precipitation-evaporation wndex: Reference used to compare the
precipitation and temperature levels of various P-E regions
of the United States.
processing plant: 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.
representative source: Source that has the mean emission
parameters.
respirable particulates: Particles with a geometric mean
diameter less than or equal to 7 ym.
rock: Stone in a mass.
severity: Hazard potential of a representative source defined as
the ratio of maximum time-averaged concentration to the
hazard factor.
shorthead: Refers to a cone crusher.
shuttle conveyor: Conveyor used to move crushed stone back and
forth between operations.
silicosis: Diffuse fibrosis of the lungs caused by the chronic
inhalation of silica dust less, than 10 ym in diameter.
sizing screen: Mesh used to separate stone into various sizes.
stone: Hard, solid, nonmetallic mineral matter of which rock is
composed.
thixotropic: Relating to a property of gels to become liquid
when shaken or disturbed.
threshold limit value: Concentration of an airborne con-
taminant to which workers may be exposed repeatedly, day
after day, without adverse effect.
*U.S. GOVERNMENT PRINTING OFFICE:1978 260-880/53 1-3 5 0
-------
/PI TECHNICAL REPORT DATA
(Please read Inttmctioni on the rtvent btfore completing)
NO.
EPA-600/2-78-004e
4. TITLE AND SUBTITLE
SOURCE ASSESSMENT: CRUSHED LIMESTONE,
State of the Art
. AUTHOR(S) ' ' '
P. K. Chalekode, T. R. Blackwood, and
S. R. Archer
3. RECIPIENT'S ACCESSION NO.
6. REPORT DATE
April 1978 issuing date
8. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
MRC-DA-747
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Monsanto Research Corporation
1515 Nicholas Road
Dayton, Ohio 45407
1O. PROGRAM ELEMENT NO.
1BB610
11. CONTRACT/GRANT NO.
68-02-1874
12. SPONSORING AGENCV NAME AND ADDRESS
Industrial Fnvironmental Research Laboratory - Cin., OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Task Final, 8/75-2/76
14. SPONSORING AGENCY CODE
EPA/600/12
IS. 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 emissions from the crushed
limestone industry. Crushed limestone plants emit particulates from
drilling, blasting, transport on unpaved roads, crushing, screening, con-
veying, and stockpiling. The emission factor for total particulate from
a representative plant producing 450 metric tons/hr of product is 3.5 g/
metric ton. Vehicular movement on unpaved roads contributes 66% of the
overall emissions and approximately 38% of the respirable particulate
emissions. The hazardous constituent in the dust is free silica (1.2% by
weight). Nitrogen oxides and carbon monoxide are emitted by the blasting
operation, but their emission factors are small in comparison to that of
particulate emissions. In order to evaluate the potential environmental
effect of crushed limestone plants, source severity was defined as the
ratio of the maximum time-averaged ground level concentration of an
emission to the ambient air quality standard for criteria pollutants or
to a modified TLV for noncriteria pollutants. The maximum source sever-
ity for particulates is 0.032; for free silica in the respirable particu-
late emissions, it is 0.12. Emissions from this industry in 1978 are
estimated to be the same as they were in 1972.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a.
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
Aggregates
Air Pollution
Carbon Monoxide
Mines
Silicone dioxide
Nitrogen Oxides
Air Pollution Contro
Stationary Sources
Source Severity
Limestone
Particulate
Quarries
silica
. COSATI Held/Group
68A
18. DISTRIBUTION STATEMENT
Unlimited
19. SECURITY CLASS (This Rep
Unclassified
61
2O SECURITY CLASS (TMspagel
Unclassified
22. PRICE
EPA Form 222O-I (*-71)
51
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