oEPA
Environmental >
Ottice of R.uii jrams
ility
PO Box 18416
Vegas NV 891 T4
EPA 520 6 82 018
November 1982
Radiation
Emissions Of Naturally
Occurring Radioactivity
From Aluminum And
Copper Facilities
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EPA-520/6-82-018
November 1982
EMISSIONS OF NATURALLY OCCURRING RADIOACTIVITY
FROM ALUMINUM AND COPPER FACILITIES
by
Vernon E. Andrews
Office of Radiation Programs-LVF
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
Project Officer
Tom Bibb
Emission Standards and Engineering Division
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
This report was prepared with the technical support
of Engineering-Science Inc. contract 68-02-2815,
and PEDCo Environmental Inc. contract 68-02-2811
Office of Radiation Programs - Las Vegas Facility
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
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DISCLAIMER
This report has been reviewed by the Office of Radiation Programs-Las
Vegas Facility, U.S. Environmental Protection Agency, and approved for
publication. Mention of trade names or commercial products does not
constitute endorsement or recommendation for use.
ii
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FORWARD
The Office of Radiation Programs (ORP) of the U.S. Environmental Protec-
tion Agency (EPA) conducts a national program for evaluating exposure of
humans to ionizing and nonionizing radiation. The goal of this program is to
develop and promote protective controls necessary to ensure the public health
and safety.
In response to the 1977 amendments to the Clean Air Act the Las Vegas
Facility was given the responsibility to collect field data on emissions to
the atmosphere of natural radioactivity from operations involved in the
mining, milling, and smelting of minerals other than uranium and coal. This
report is one of a series which describes an individual facility and its
associated radioactive emissions.
ORP encourages readers of the report to inform the Director, ORP-Las Vegas
Facility, of any omissions or errors. Comments or requests for further infor-
mation are also invited.
Wayne A. Bliss
Acting Director
Office of Radiation Programs-LVF
iii
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CONTENTS
Page
Forward iii
Figures vi
Tables vi
Abbreviations and Symbols vii
1. Introduction 1
2. Sample Collection and Analysis 3
Sample collection 3
Sample analysis 3
Data reporting 4
3. Bauxite Mine (Aluminum Industry) 5
Process description 5
Results 5
4. Alumina Reduction Plant 7
Process description 7
Results 9
5. Aluminum Reduction Plant 13
Process description 13
Results 15
6. Underground Copper Mine and Mill 17
Process description 17
Results 20
7. Open Pit Copper Mine and Concentrator 21
Process description 21
Sampling points 22
Sample results 22
References 28
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FIGURES
Number Page
1 Uranium and thorium radioactivity decay schemes 2
TABLES
Number Page
1 Bauxite Pit Radon Emanation Rates 6
2 Radioactivity in Alumina Plant Process Samples 8
3 Alumina Plant Particulate Radioactivity Rate 9
4 Alumina Plant Ambient and Stack Radon-222 Measurements 10
5 Brown Mud Tailings Radon Emanation Rates 12
6 Radioactivity Aluminum Reduction Plant Process Samples 14
7 Aluminum Reduction Plant Emission Rate 15
8 Underground Copper Mine and Mill Process Sample Radioactivity ... 18
9 Underground Copper Mine and Mill Radon-222 Measurements 19
10 Open Pit Copper Mine and Concentrator
Process Sample Radioactivity 23
11 Ambient Station Radon-222 Concentrations - Open Pit Copper Mine . . 24
12 Copper Mine Crusher and Concentrator - Radon-222 Measurements ... 25
13 Average Annual Emissions From An Open Pit Copper Mine 26
14 Aerodynamic Particle Size Distributions from
Open Pit Copper Mine 26
15 Open Pit Copper Mine Radon Emanation Rates 27
vi
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LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
Ci *
fCi/m3
mCi/g
nCi/nv3
pCi
pCi/g-
pCi/irr-min
TSP
urn
SYMBOLS
AMAD
EIC
GMD
GSD
HSS
MSHA
curies, 3.7 x 10]° disintegration per second
femtocuries (10~15 curies) per cubic meter
millicuries (10~3 curie) per gram
nanocuries (10'9 curie) per cubic meter
picocuries, 10~'2 curies
picocuries per gram
picocuries per square meter per minute
total suspended particulates
micrometer, 10~6 meter
activity mean aerodynamic diameter
Eberline Instrument Corporation
geometric mean diameter
geometric standard deviation
Horizontal Stud Soderberg
Mine Safety and Health Administration
VI1
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SECTION 1
INTRODUCTION
The Clean Air Act, as amended in August 1977, required the Administrator
of the Environmental Protection Agency (EPA) to determine whether emissions of
radionuclides into ambient air should be regulated under the Act. In December
1979 the Administrator listed radionuclides as a hazardous pollutant under
Section 112 of the Clean Air Act.
The naturally occurring radionuclides most likely to be emitted in signif-
icant quantities are those in the uranium-238 and thorium-232 decay series
(Figure 1). These radionuclides and their daughter products occur naturally
in widely varying amounts in the soils and rocks that make up the earth's
crust. Average values for uranium-238 and thorium-232 in soils are approxi-
mately 1.8 ppm (0.6 pCi/g) and 9 ppm (1 pCi/g) respectively (1). The radio-
activity concentration of each of the daughter products in the two series is
approximately equal to that of the uranium-238 or thorium-232 parent.
Almost all operations involving removal and processing of soils and rocks
release some of these radionuclides into the air. These releases become
potentially important when the materials being handled contain above-average
radionuclide concentrations or when processing concentrates the radionuclides
significantly above the average amounts in soils and rocks.
Because mining and milling operations involve large quantities of ore, and
because there is little information about how these activities release radio-
active emissions, EPA, in 1978, began to measure airborne radioactive emissions
from various mining, milling, and smelting operations.
Operations were selected for study on the basis of their potential to emit
significant quantities of naturally occurring radionuclides to the atmosphere.
Some of the factors in the selection included typical mine size, annual U.S.
production, measured working levels of radon daughters in underground mines
and associated ventilation rates, production rate and process of individual
facilities, and previous association with naturally occurring radionuclides.
Usually, we chose to look at large facilities in order to improve the chances
of obtaining emission samples with radioactivity contents significantly
greater than background.
These surveys were screening studies designed to identify potentially
important sources of emissions of radionuclides into the air. Any such
sources can then be studied in detail to determine whether or not a national
emission standard for hazardous pollutants is needed under the Clean Air Act.
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URANIUM - 238 DECAY SERIES
THORIUM - 232 DECAY SERIES
238
U
4 5x1O»yr
!
Of
234
Th
24 da
234
Pa
6 75 hr
. /I
/,,
234
U
2.5x105yr
t
a.V
t
230
Th
8x104yr
i
0,7
>
226
Ra
1620yr
i
a.y
222
Rn
3 8da
I
a, X
218
Po
3min.
Of
214 210
Po Po
1.6x104sec. 138da.
* j '
214 / a Y 210 /„
B, ^ ' B, '* "•*
197min 5 da.
214
Pb
27 mm
/B.y 210 /ft,y 206
/ Pb / Pb
19.4yr. Stable
Figure 1. Uranium and thorium radioactivity decay schemes.
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SECTION 2
SAMPLE COLLECTION AND ANALYSIS
SAMPLE COLLECTION
Most samples were collected using EPA reference methods (2). Stack
sampling points were selected according to EPA Method 1, "Sample and velocity
traverses for stationary sources." Stack gas velocity and volumetric flow
rate were determined by EPA Method 2, "Determination of stack gas velocity and
volumetric flow rate (type S pitot tube)." Gas samples for radon-222 analysis
were collected using EPA Method 3, "Gas analysis in carbon dioxide, oxygen,
excess air, and dry molecular weight." Total suspended particulates (TSP) in
ducts and exhaust stacks were determined using EPA Method 5, "Determination of
particulate emissions from stationary sources," or EPA Method 17, "Determina-
tion of particulate emissions from stationary sources (in-stack filtrations
method)." High volume ambient TSP samples were collected in accordance with
the "Reference Method for the Determination of Suspended Particulates in the
Atmosphere (3)."
Several contractors performed the sample collection. They used 7.6-cm
(3-inch) glass fiber filters for Method 5 samples or 5- by 12.7-cm (2- by
5-inch) glass fiber filters for Method 17 samples. The contractors used 20.3-
by 25.4-cm (8- by 10-inch) Microsorban polystyrene fiber filters for ambient
TSP samples. Stack and ambient whole air samples for radon analysis were
collected in Tedlar bags of 20 to 30 liter capacity.
Generally one set of duplicate radon samples was collected at each
sampling point as part of the quality assurance program. When possible,
duplicate Method 5 particulate samples were collected from one or two stacks
at a given facility.
The contractors collected samples of process materials so that
radionuclide emission rates could be compared to the radioactivity of the
material handled at that point.
SAMPLE ANALYSIS
The contractors made mass determinations on the various TSP sample
fractions before forwarding them for radiological analysis. Eberline
Instrument Corporation (EIC) performed the radiological analyses of all samples
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except for some duplicate radon samples that were analyzed by EPA in our
Las Vegas laboratory as an interlaboratory cross-check.
EIC analyzed process and TSP samples by dissolving the samples and
separating the elements of interest by chemical techniques. The separated
uranium and thorium fractions were counted on alpha spectrometers for
individual isotopic quantisation. An alpha scintillation counter measured the
polonium-210. Lead was separated and set aside for about 2 weeks to allow for
ingrowth of bismuth-210 from lead-210. After the ingrowth period the
bismuth-210 was separated from the lead and was counted on a beta counter to
quantitate lead-210. Radium was separated and enclosed as a solution in a
sealed tube to allow for ingrowth of radon from radium-226. After three weeks
of ingrowth the radon gas was evolved and collected in an alpha scintillation
cell to be counted. Stack and ambient gas samples were transferred to alpha
scintillation cells and counted for radon.
DATA REPORTING
The radioactivity reported for each sample, except for radon collected on
charcoal canisters, is the net radioactivity plus or minus twice the standard
deviation (2s). The net radioactivity is the gross sample radioactivity minus
the counting equipment background and minus either a) for filter samples an
average value for the radioactivity content of a blank filter, or b) for stack
radon samples, the ambient radon concentration. The standard deviation is
based only on the random variations inherent in radioactivity counting and is
propagated through the various steps to the final result. This random
variation, plus the variable radioactivity content of individual filters
occasionally results in a net radioactivity of less then zero. Of course'
there is no negative radioactivity. In these cases, as with all others, the
net result must be considered along with the standard deviation. Averages of
multiple emission samples are given with the standard error of the mean.
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SECTION 3
BAUXITE MINE (ALUMINUM INDUSTRY)
PROCESS DESCRIPTION
Bauxites, the principle aluminum ore, are known to have substantially
higher levels of uranium and thorium than the parent rock (5). ORP included a
domestic bauxite mine as part of this project.
At the survey site, bauxite was mined from open pits which varied in
approximate area from 0.3 to 30 hectares. Typical pit dimensions were 40 by
700 m. The mining company conducted pit development by expanding the pit in a
direction perpendicular to the long side. Overburden removed by dragline was
used to fill the previously mined area which was then reclaimed. Dragline
operations were conducted 24 hours per day. The day shift drilled and loaded
blasting holes in the ore which were blasted at the end of the shift. The
coarsely broken ore was hauled by truck to storage areas or to the alumina
plant. The high moisture content of overburden and ore prevented production
of airborne particulates during mining operations. Water was applied to
haulage roads as necessary to prevent any dust problem.
The area of potential concern regarding radioactivity emissions was radon
emanation from the surface of the ore body and overburden piles. Some radon
is probably released during blasting, but the ore is generally quite coarse so
that release is minimal. Activated charcoal canisters were emplaced on the
ore body, exposed faces of overburden, spoils piles, and undisturbed soil.
RESULTS
Radon emanation rates measured are shown in Table 1. The average observed
rate of 45 ± 15 pCi/mz-min from the ore body surface is twice the observed
background rate of 22 * 11. The exposed surface of the ore body is less than
that of both the overburden and spoils area. The average radon emanation rate
for the entire developed pit area of about 20 pCi/m2_min is about equal to
the background rate for the area.
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TABLE 1. BAUXITE PIT RADON EMANATION RATES
Location
Top of ore body
Top of ore body
Top of ore body
Average
Radon Emanation Rate
(pCi7nr-nrin)a
35
62
39
45 ± 15b
Top of overburden - topsoil removed
Overburden sidewall, 5 ft. below top
Overburden sluffage berm, midway
between surface and top of ore
Average
5.9
13
2.6
7.2 ± 5.3
Spoils area
Spoils area
Average
4.9
12
8.5 ± 5.0
Pit background, undisturbed soil
Pit background, undisturbed soil
Pit background, undisturbed soil
Pit background, undisturbed soil
Average
27
9.6
16
35
22 ± 11
a) Picocuries (10~ curies) per square meter per minute.
b) Uncertainties of averages are standard deviation about the mean.
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SECTION 4
ALUMINA REDUCTION PLANT
PROCESS DESCRIPTION
The alumina reduction plant surveyed used a modified "American Bayer"
process to recover alumina (aluminum oxide) from bauxite ore. Red mud, the
waste material resulting from this process, is further treated in a lime-sinter
process to remove sodium aluminum silicate in the form of pure chemical grade
alumina hydrates. The final waste product is referred to as brown mud.
Imported South American ore and domestic ore are blended and used as
described above. Imported Jamaican ore is used separately and is treated only
by the Bayer process. In the Bayer process ore is wet ground in rod mills.
The resulting slurry passes through a digestion process to dissolve the
alumina in caustic liquor which is separated from the red mud. Alumina
trih^drate is precipitated from the liquor, washed, filtered, and calcined at
1150,C (2100°F) in rotary kilns to produce alumina, which may be shipped as is
or may receive further chemical processing for metallurgical and chemical
alumina uses.
Red mud from the Bayer process is filtered and' reslurried with the
addition of limestone and soda ash, then is ball milled. The milled slurry is
sintered at 1260°C (2300°F) in rotary kilns. Sinter is ball milled with water
to dissolve sodium aluminate formed during sintering. After purification the
sodium aluminate liquor is routed to precipitators for recovery of chemical
grade hydrates.
Radon present in the ore is presumed to be lost to the atmosphere during
the milling and digestion processes. No single source of emission exists to
sample such emissions. Radon concentrations were measured in the exhausts of
the Bayer process, alumina hydrate vacuum filter, rotary kiln, and red mud
vacuum filter. Also radon was measured in exhausts from the lime-soda process,
lime and sinter kilns, and in natural gas fuel to alumina and sinter kilns.
Radon emanation from the brown mud tailings area was measured with charcoal
canisters.
TSP and size-fractionated particulate samples were collected from the
alumina kiln electrostatic precipitator inlet and exhaust and from the red mud
kiln exhaust.
Process samples included domestic ore from the mine pit surveyed, blended
bauxite, alumina kiln feed, alumina product, chemically treated alumina product
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TABLE 2. RADIOACTIVITY IN ALUMINA PLANT PROCESS SAMPLES
Radioactivity Concentrations (pd/g)a
co
Sample
Bauxite Ore
Blended Bauxite
Alumina Ki In Feed
Alumina Product
RC-64 Alumina
Red Mud Filter Cake
Prepared Sinter Mud
Sinter
Brown Mudb
U-238
6.8
4.0
0.05
0.28
0.31
7.5
4.8
6.4
5.5
± 0.7
* 0.5
± 0.03
± 0.10
* 0.09
* 1.2
* 0.5
* 0.8
* 0.4
U-234
6.9
4.0
0.07
0.28
0.35
7.5
4.7
6.6
5.6
± 0.7
± 0.5
± 0.03
± 0.10
* 0.10
* 1.2
* 0.5
± 0.9
± 0.5
Th-230
6.4 ±
3.5 ±
<0.
<1
1.1
0.3
05
<0.6
5.1 *
4.2 *
6.5 *
8.0 ±
1.3
1.1
1.6
2.7
Ra-226
7.4
4.4
0.08
0.23
0.19
6.5
3.9
3.9
5.6
± 2.2
± 1.3
± 0.05
± 0.07
* 0.06
* 2.0
* 1.2
* 1.2
* 1.2
Pb-210
9.1
5.3
0.20
<]
<]
7.6
6.8
3.6
5.7
± 1.1
* 0.4
± 0.15
L.4
..3
± 0.4
* 0.4
± 0.4
± 0.8
Po-210
10.0 ± 1
4.2 ± 0.5
0.00 ± 0.20
<0.6
<0.6
7.7 ± 1.7
4.6 ± 0.5
3.2 ± 1.2
5.4 ± 0.7
Th
5.5
5.2
<0
<0
<0
5.0
5.0
9.2
12.5
-232
± 1.0
* 1.2
.05
.2
.2
* 1.5
± 1.3
± 2.1
± 4
Th-228
5.5 ± 1.0
5.6 ± 1.2
<0.05
<0.2
<0.2
6.3 * 1.5
5.5 ± 1.4
8.6 * 2.0
12.5 ± 4
a) Picocuries (10-1? curies) per gram plus or minus twice the standard deviation based on counting statistics.
b) The results are derived from duplicate samples.
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(RC-64), red mud filter cake, prepared sinter mud, sinter, and brown mud
tailings.
RESULTS
As shown in Table 2, the bauxite ore was elevated in both uranium-238 and
thorium-232 with concentrations of 6.8 and 5.5 pCi/g. The addition of
imported ore reduced the concentration of uranium to 4.0 pCi/g. Removal of
alumina, which contained only 0.05 pCi/g of uranium-238 and less than 0.05
pCi/g of thorium-232 resulted in increasing the concentrations in red mud.
The uranium and thorium concentrations were again diluted by the addition of
lime and soda ash to about 5 pCi/g. The first fractionation of radioactivity
occurred in the sinter kiln where lead-210 and polonium-210 were reduced to
about half the concentration of the precursors. The brown mud lake tailings
results, collected from the vicinity of the charcoal canisters, shows that the
lead-210 to be in approximate equilibrium with its precursors and polonium-210
to be in equilibrium with lead-210. Lead-210 in the other process samples
appears to be biased high, relative to uranium and the same bias probably
applies here as well. Because of the age of the tailings sample the
polonium-210 would have grown to some higher degree of equilibrium than in the
sinter material.
The low radioactivity of alumina is reflected in the radioactivity
emissions from the alumina kilns (Table 3). Even though kiln 4 was found to
be emitting about 20 times as much mass as usual, probably due to an
inoperative electrostatic precipitator, the estimated annual release for the
four kilns operating during the survey was 0.068 mCi/y for uranium-238 and
-234 and <0.055 mCi/y for radium-226.
TABLE 3. ALUMINA PLANT PARTICULATE RADIOACTIVITY EMISSION RATES
Source
Hood System 1
Hood System 3
Stacks'5
U-238
<0.7
<2.0
<6.0
U-234
<1.0
<0.7
<4.0
Th-230
<2.0
<2.0
<3.0
Ra-226
<0.4
<0.3
<2.0
Pb-210
8.1
7.8
32.0
Po-210
<5.0
7.5
<27
Th-232
<2
a
<6
Th-22!i
<2
<1
<6
a) Estimated from Method 5 contractor results
b) Four stack total
Emissions of radionuclides from the red mud sinter kiln were below
measurable concentrations except for lead-210 and polonium-210. The high
temperatures caused a large fraction of those to be volatilized, as shown by
the process sample results. Emissions of the two nuclides were essentially
equal with 7.8 mCi/yr for lead-210 and 9.3 mCi/yr for polonium-210.
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TABLE 4. ALUMINA PLANT AMBIENT AND STACK RADON-222 MEASUREMENTS
Collected
Concentrations (nCI/m3)3 Annual
Source
Ambient Air
Alumina
Alumina
Time
1252-1650
0955-1417
0941-1332
1319-1618
1009-1358
0956-1301
Date
11/13/79
11/14/795
11/15/79
11/13/79
ll/14/79b
11/15/79
Gross
0.13
0.16
0.45
0.07
0.25
0.29
Net
± 0
± 0
± 0
± 0
± 0.
± 0,
.04
.03
.08
.03
.04
.07
Source Average
Alumina
1315-1606
0925-1230
1013-1332
11/13/79
11/14/79
ll/15/79b
0.49
0.50
0.52
± 0.
± 0.
± 0.
,07
06
05
Source Average
Alumina
1314-1621
1337-1345
1010-1322
ll/13/79b
11/14/79
11/15/79
0.53
0.47
0.55
± 0.
± 0.
± 0.
05
06
11
Source Average
Red Mud
Total for
1145-1611
0941-1338
4 Kilns
11/13/79
11/14/795
0943-11/15/79
1.5
2.1
1.5
± 0.
± 0.
± 0.
1
1
1
-0.06
0.
.09
-0.16
-0.04
0.
0.
0.
0.
0.
0.
0.
0.
1.
1.
1.
.36
,34
07
,26
40
31
10
27
4
9
0
Emissions(Ci/Yr)
± 0.05
± 0.
± 0,
,05
.11
± 0.18
± 0.
± 0.
± 0.
± 0.
± 0.
± 0.
± 0.
± 0.
± 0.
± 0.
± 0.
,08
08
09
16 0.074
06
08
14
15 0.067
0.27
1
1
1
Source Average
1.4 ±0.5
0.019
10
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TABLE 4. (Continued)
Collected
Concentrations (nCi/nrJa Annual
Source
Lime Kiln
Red Mud
Time
1216-1552
1228-1606
0930-1331
0930-1320
Date
11/13/79
ll/13/79b
11/14/79
11/15/79
Gross
0
1
.03
.2
1/3
1
.7
± 0
± 0
± 0
± 0
.01
.1
.1
.1
Source Average
-0
1
1
1
1
Net
.13
.1
.1
.2
.1
± 0.
± 0.
± 0.
± 0.
* 0.
Emi
04
1
1
1
1
ssions(Ci/Yr)
0.39
Total for 5 kilns
2.0
Natural Gas 1515
11/15/79'
5.8 ± 0.1
a) Nanocuries (10~9 curies) per dry, standard cubic meter (20*C, 760 mm
mercury pressure) plus or minus twice the standard deviation based either on
counting statistics or in the case of source averages on sample variance..
b) The results are derived from duplicate samples.
11
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Two size-fractionated particulate samples were collected from the alumina
kiln 8 stack and from the sinter kiln stack. Radioactivity was below detect-
able levels on the size fractions collected from the alumina kiln, but the
mass distribution by aerodynamic particle size for the two samples showed a
geometric mean diameter (GMD) of 2.2 urn with a geometric standard deviation
(GSD) of 2.4 on one sample and a GMD of 3.3 um with a GSD of 2.8 on the other.
The sinter kiln aerodynamic size distribution was a GMD of 2.3 um and GSD of
3.9 on one sample and a GMD of 2.4 vm and GSD of 3.8 on the other. Radio-
activity levels on the first sinter kiln sample, analyzed by individual stages
were below detectable. Compositing of stages from the second sample resulted
in detectable quantities of polonium-210 being measured. Polonium-210
activity mean aerodynamic diameter (AMAD) was 5.5 ym with a GSD of 8.1. This
result was the opposite of the expected AMAD of less than 1 um and low GSD.
The highest average radon concentration in a stack was measured on the
discharge from the red mud vacuum filter at 1.4 ± 0.5 nCi/m3 (Table 4).
With a low exhaust flow rate it emitted only 0.019 Ci/y. The largest process
source of radon-222 was the red mud sinter kiln with a single kiln emission
rate of 0.39 Ci/y. Total for the five kilns operating at that time was
2.0 Ci/y. The alumina kiln emissions averaged .074 Ci/y from kiln 4 and
.067 Ci/y from kiln 8 with an average for four operating kilns of .27 Ci/y.
It is probable, considering the low radioactivity of alumina and the negative
result for the discharge rate of radon-222 from the alumina vacuum filter,
that the alumina kiln emission was due to radon-222 in the natural gas fuel.
Natural gas was found to have a radon-222 concentration of 5.8 ± 0.1 nCi/m3.
mud
Charcoal canister radon-222 emanation measurements from the brown
tailings lake and an undisturbed area nearby are shown in Table 5. The over-
lapping confidence intervals rule out any finding of a significant difference
between the emanation rate averages.
TABLE 5. BROWN MUD TAILINGS RADON EMANATION RATES
Emanation Rates (pCi/m2-min)a
Tailings Background
67 —tr—
33 40
43 26
48 5
15
11
, 19 ^
Average0 34 ± 20 23 ± 14
a) Picocuries (10-12 curies) per square meter per minute.
b) Average plus or minus the standard deviation about the mean.
12
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SECTION 5
ALUMINUM REDUCTION PLANT
PROCESS DESCRIPTION
Aluminum metal is produced from alumina by the "Hall" electrolytic
reduction process. An electric current passed through a large shallow pot of
cryolite (Na3AlF6) raises the temperature to about 975*C, which maintains
the cryolite in a molten state. Alumina, in a fine powder form, is
periodically added to the surface of the molten cryolite which serves as both
an electrolyte and solvent for the alumina. Small amounts of aluminum
fluoride are added to maintain the optimum level of fluoride which is lost in
the pot emissions.
A carbon lining in the pot serves as the cathode and a carbon anode is
immersed in the molten cryolite from above the pot. Two forms of anode are
used, either prebaked anodes consisting of large blocks of petroleum coke or
an asphalt pitch binder which is baked to a hard carbon. These are replaced
as the anodes are consumed by the oxygen released in the alumina reduction
process. Horizontal Stud Soderberg (HSS) anodes use a process in which a
coke-pitch mixture is placed in a hopper atop the pot. Horizontal metal
studs, which also serve as the electrical connection, are inserted into the
mass above the molten surface. The high temperature of the pot bakes the
mixture into a solid carbon mass as it nears the pot. The studs are
periodically withdrawn and inserted higher to allow the anode to descend as it
is consumed.
Several processes, including materials handling and electrode preparation,
produce atmospheric emissions of vapors and particulates which were not con-
sidered to be significant sources of radioactivity. The only sources of
concern to this survey were the controlled and uncontrolled emissions from the
reduction pots. Reduction pot operation is essentially an open process but
hoods are employed to control emissions. Several techniques for hooding the
pots were being evaluated to determine the optimum for each pot type Wet
scrubbers treat the fumes collected from groups of 40 pots before discharging
the exhaust to the atmosphere through 36 m stacks. Eighty pots in each of two
buildings comprise the pot line. Each building, approximately 350 m long, is
ventilated by natural circulation through roof ridgeline monitors. The combi-
nations of winds and thermal rise from the hot pots produces a reported
ventilation rate of one air change every minute or two.
13
-------
TABLE 6. RADIOACTIVITY ALUMINUM REDUCTION PLANT PROCESS SAMPLES
Radioactivity Concentrations (pCi/q)a
Sample
Alumina
Alumina
Average
Aluminum Fluoride
Aluminum Fluoride
Average
Cryolite
Cryolite
Average
Aluminum
Aluminum
Average
U-238
0.08
0.12
0.10
0.13
0.08
0.11
0.11
0.11
0.04
0.15
0.10
* 0.05
± 0.06
± 0.04
± 0.05
* 0.05
* 0.04
* 0.06
* 0.06
* 0.03
± 0.06
* 0.03
0
0
0
0
0
0
0
0
0
0,
0
0
U 234
.11
.13
.12
.26
.13
.20
.12
.09
.11
.09
.10
.10
* 0.06
± 0.06
± 0.04
± 0.08
* 0.06
± 0.05
* 0.06
* 0.05
* 0.04
± 0.05
* 0.05
± 0.04
Th-230
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
Ra-226
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
20 ±
14 *
17 *
12 ±
12 ±
12 ±
15 ±
12 *
14 *
15 ±
14 ±
15 ±
0.06
0.04
0.04
0.04
0.04
0.03
0.04
0.04
0.03
0.04
0.04
0.03
Pb 210
<1 .4
<1.6
<1.5
<1.5
<1 .4
<1.5
<1.6
<1 .6
<1 .6
<1.5
<1 .6
<1 .6
Po-21i
<0.7
<0.7
<0.7
<0.7
<0.7
<0.7
<0.7
<0.7
<0.7
<0.7
<0.7
<0.7
Th-232
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
>0.2
Th-228
<0.2
<0.2
<0.2
<0.2
<0.2
<0.2
>0.2
>0.2
<0.2
<0.2
<0.2
>0.2
a) Picocuries (10 curies) per gram plus or minus twice the standard deviation based on counting statistics.
b) Picocuries per gram plus or minus the standard deviation based on sample variance.
-------
RESULTS
Two exhaust stacks were sampled. One handled emissions from 40 HSS pots
and one handled emissions from 20 HSS pots and 20 prebake pots. High volume
air samplers collected participate emissions from the roof monitors over each
building. Radon was measured in the stack emissions and at the roof monitors.
The company provided samples of alumina, aluminum fluoride, cryolite, and
aluminum. All materials exhibited similar radioactivity concentrations,
averaging 0.13 pCi/g for those uranium chain nuclides which were present in
detectable quantities (Table 6).
Radon-222 in stack emissions and building ventilation air was found to be
indistinguishable from ambient levels.
Only lead-210 and polonium-210 were collected from the hooding system
exhaust stacks in measurable quantity. Lead-210 emissions averaged 8.1 mCi/y
in hooding system 1 and 7.8 mCi/y in hooding system 3 (Table 7). The total
from the four stacks was 32 mCi/y. Polonium-210 averaged <6 mCi/y from
hooding system 1 and 7.5 from hooding system 3, with a four-stack total of 27
mCi/y. The total emissions of the other particulate radionuclides averaqed
<8 mCi/y.
TABLE 7. ALUMINUM REDUCTION PLANT EMISSION RATE
Source U-238 U-234
Alumina 0.068 0.058
Kilnsb
Red Mud
Sinter Kilnsc
Th-230 Ra-226 Pb-210
<0.24 <0.055 <0.34
7.8
Po-210
<0.14
9.3
Th-232 Th-22t'
<0.05 <0.05
a) Estimate from Method 5 contractor results.
b) Total emissions from four kilns
c) Total emissions from six kilns
Lead-210 and polonium-210 were collected in measurable quantities on the
high volume filter samples collected from the roof monitor of the north pot
room. No measurable quantities of any radionuclides were collected from the
south building roof monitor. Roof access limited sampling to the south side
of the north building roof monitor and to the north side of the south building
roof monitor. Wind directions may have influenced the flow of particulates
through the monitors, but mass loading on the south building samples were
higher than on the north building samples. Concentrations measured in the
north building roof monitor were: lead-210, 8 ± 220 fCi/m3; polonium-210,
200 * 250 fCi/iTH. The concentrations measured the following day were'
lead-210, 60 * 130 fCi/nP; polonium-210, 550 ± 210 fCi/m3. The relatively
high uncertainties associated with the net concentrations result from the
relatively large and variable blank filter analyses. These compare to ambient
15
-------
concentrations measured near the plant of: lead-210, 16 ± 6 fCi/m3;
polonium-210, 17 ± 6 fCi/m3. The average lead-210 emission concentration of
16 ± 6 fCi/m3; polonium-210, 17 ± 6 fCi/m3. The average lead-210 emission
concentration of 33 ± 26 fCi/m3 did not differ significantly from ambient.
The average polonium-210 concentration of 380 * 180 was significantly higher
than ambient. Assuming one air change every 2 minutes the annual emissions of
polonium-210 from the building, based on the two samples, would be 17 mCi.
16
-------
SECTION 6
UNDERGROUND COPPER MINE AND MILL
PROCESS DESCRIPTION
Selected for this survey was an underground copper-iron-zinc-sulfide mine.
The Mine Safety and Health Administration (MSHA) had reported average radon
daughter WL* measurements of 0.087 with a maximum of 0.21. (personal communi-
cation with Aurel Goodwin, MSHA). The ore runs less than 1 percent copper,
less than 1 percent zinc, 20 percent iron, and 25 percent sulfur. A mill and
flotation plant produces concentrates of the three sulfides and disposes of
about 50 percent of the ore as tailings.
The mine operates three shifts per day, 5 days per week. Blasting of the
drilled ore is done at about 1500 hours each day. An exhaust fan housed above
a vertical shaft into the mine provides a ventilation rate of 2,660 m3-min
through the mine. Air discharge is horizontal at ground level through a
1.76-m diameter outlet.
Ore from the mine surveyed, from another adjacent underground mine, and an
adjacent open pit mine is processed in the flotation plant. Primary and
secondary crushers reduce the ore to less than 2-inch size before it enters
the ball mills of the flotation plant. A rotoclone wet scrubber cleans the
emissions from the crushers. The scrubber discharges horizontally about 4 m
above ground at 484 m3-min. The mill produces about 15,000 tons each of
copper and zinc and 300,000 tons of iron as sulfides per year.
As shown in Table 8, the uranium decay chain nuclides were at or slightly
above the average concentrations found in crystal rock. The ore concentration
averaged about 1 pCi/g.
As would be expected in a process which is designed to selectively
concentrate metals, the concentrates generally have lower radionuclide
concentrations than the ore or tailings. The zinc concentrating process seems
to be the most discriminating with concentrations averaging 40 percent of
those in ore.
* Working Level (WL) is defined as any combination of short lived radon
daughter products in one liter of air that will result in the ultimate
emission of 1.3 x lO^ Mev of potential alpha energy (U.S. Public Health
Service publication No. 494, 1957).
17
-------
TABLE 8. UNDERGROUND COPPER MINE AND MILL PROCESS SAMPLE RADIOACTIVITY
Sample
U-238
U-234
Th-230
Radioactivity Concentrations (pCi/g)a
Ra-226 Pb-210 Po-210
Th-232
Th-228
Ore
Average
Copper
Concentrate
Average
Zinc
Concentrate
Average
Iron
Concentrate
Average
Tailings
Average
0.79 * 0.14
0.78 ± 0.19
0.79 ± 0.20
0.79 ± 0.10
0.63 ± 0.14
0.59 ± 0.15
0.73 ± 0.17
0.65 ± 0.09
0.28 ± 0.07
0.29 ± 0.07
0.37 * 0.09
0.31 ± 0.04
0.37 ± 0.11
0.42 * 0.10
0.52 * 0.12
0.44 * 0.06
0.86 * 0.16
0.88 * 0.18
0.71 ± 0.12
0.82 ± 0.09
0.72 * 0.13
0.93 * 0.22
0.80 ± 0.20
0.82 ± 0.11
0.63 ± 0.15
0.57 ± 0.16
0.78 ± 0.18
0.66 ± 0.09
0.33 ± 0.08
0.36 * 0.08
0.41 * 0.10
0.37 * 0.05
0.38 ± 0.11
0.47 * 0.10
0.51 ± 0.12
0.45 * 0.06
0.79 * 0.15
0.84 ± 0.16
0.77 ± 0.13
0.80 * 0.08
0.92 * 0.60
1.6 ± 0.4
1.5 ±0.9
1.3 * 0.4
0.73 * 0.21
0.87 ± 0.29
0.98 ± 0.34
0.86 ± 0.16
0.52 * 0.24
0.42 * 0.18
0.34 ± 0.18
0.43 ± 0.12
0.44 * 0.30
0.72 ± 0.1S
0.94 * 0.26
0.70 * 0.15
0.86 * 0.22
1.1 * 0.2
1.3 ± 0.2
1.1 * 0.1
0.33 ± 0.20
1.4 ± 0.4
0.69 ± 0.21
0.81 * 0.16
0.84 * 0.25
0.99 * 0.30
0.77 * 0.23
0.87 * 0.15
0.17 ± 0.05
0.44 ± 0.13
0.40 ± 0.12
0.34 * 0.06
0.10 ± 0.06
0.86 * 0.26
0.52 ± 0.16
0.49 ± 0.10
0.76 ± 0.23
1.4 ± 0.4
0.41 * 0.12
0.86 * 0.16
0.80 * 0.43
2.1 * 2.0
1.1 * 0.4
1.3 ± 0.7
0.84 ± 0.64
0.41 ± 0.29
0.44 * 0.27
0.56 * 0.25
0.45 * 0.22
0.52 ± 0.32
0.67 ± 0.28
0.55 ± 0.16
0.8 ± 1.8
0.60 ± 0.36
0.86 ± 0.75
0.75 * 0.66
1.3 ± 0.7
1.2 ± 0.9
0.97 ± 0.58
1.2 * 0.4
0.73 ± 0.39
2.0 * 1.9
t.O * 0.4
1.2 * 0.7
0.76 ± 0.58
0.41 ± 0.29
0.41 ± 0.25
0.53 * 0.23
0.41 ± 0.20
0.48 * 0.29
0.62 * 0.26
0.50 * 0.15
0.8 ± 1.6
0.55 ± 0.33
0.80 ± 0.70
0.72 ± 0.59
1.2 ± 0.7
1.1 * 0.8
0.90 * 0.54
1.1 * 0.4
0.53 ± 0.46
0.46 * 0.17
0.88 ± 0.61
0.62 * 0.26
0.04 ± 0.04
0.14 * 0.09
0.04 * 0.05
0.07 * 0.04
0.10 ± 0.09
-0.01 * 0.03
-0.18 ± 0.12
-0.03 ± 0.05
0.10 ± 0.12
0.09 ± 0.05
0.37 ± 0.14
0.19 ± 0.06
0.19 ± 0.8
0.23 ± 0.09
0.29 * 0.06
0.24 * 0.27
0.36 * 0.31
0.44 ± 0.16
0.88 ± 0.61
0.56 ± 0.23
0.04 ± 0.04
0.13 * 0.09
0.04 ± 0.05
0.07 * 0.04
0.07 * 0.06
0.18 * 0.09
-0.18 * 0.12
0.02 * 0.05
0.10 * 0.12
0.09 * 0.05
0.37 * 0.14
0.19 ± 0.06
0.19 * 0.08
0.22 ± 0.09
0.25 ± 0.06
0.22 * 0.04
a) Picocuries (10 curies) per gram plus or minus twice the standard deviation based on counting statistics.
b) Picocuries per gram plus or minus the standard deviation based on sample variance.
-------
TABLE 9. UNDERGROUND COPPER MINE AND MILL RADON-222 MEASUREMENTS
Collected
Concentrations (nCi/m )a
Source
Time
Date
Gross
Net
Annual
Emissions(Ci/Yr)
Ambient Air 1000-1400 1/30/79
1600-1835 1/30/79
2300-0215 1/31-2/01
0940-1200 2/01/79
1202-1350 2/01/79
0.64 ± 0.28
0.40 ± 0.16
0.14 ± 0.20
-0.01 * 0.14
-0.03 ± 0.20
Crusher 1625-1720 1/30/79
1500-1700 2/01/791
0.26 ± 0.14
0.02 ± 0.13
Mine Outlet 1230-1500 1/30/79
1530-1800 1/30/79
2305-0235 1/31-2/01
0950-1210 2/01/79
1212-1400 2/01/79
1410-1630 2/01/79
Mine Outlet Average
4
6
4
5
2
4
.6
.0
.0
.4
.8
.8
±
±
±
±
±
±
0
0
0
0
0
0
.2
.4
.2
.4
.4
.4
4
5
3
5
2
4
.0
.6
.9
.4
.8
.8
±
±
±
±
±
±
0
0
0
0
0
0
.3
.4
.3
.4
.4
.4
4.4 * 1.1
6.2
Crusher 1626-1720 1/30/79 0.68 ± 0.16
1500-1700 2/01/79 1.8 ± 0.2
Crusher Exhaust Average
0.42 ± 0.23
1.8 * 0.3
1.1 ± 1.0
0.28
a) Nanocuries (10~9 curies) per cubic meter plus or minus twice the standard
deviation based on counting for individual sample results; plus or minus the
standard deviation of the mean for source averages.
b) The results are derived from duplicate samples.
19
-------
RESULTS
Ambient radon concentrations measured near the facility and discharges
from the mine and the mill crusher are shown in Table 9. During the latter
part of the survey, snow-cover apparently reduced the ambient radon concentra-
tion by reducing radon emanation from soil. Radon concentrations in mine
exhaust air averaged 4.4 ± 1.0 nCi/m3 with an annual estimated emission of
6.2 Curies. Some disagreement exists between the MSHA WL measurements and EPA
radon measurements in the mine exhaust. The MSHA reported an average of
0.087 WL would require a radon concentration of 8.7 nCi/m3 at 100 percent
equilibrium. One or both sets of measurements may be biased, or mine
operations may have changed.
Radon in the crusher exhaust averaged 1.1 ± 1.0 nCi/m3 above ambient
levels, with a net annual emission of 0.28 curies.
Radioactivity in suspended particulates in the crusher exhaust were not
significantly greater than zero. Annual emissions of individual uranium chain
radionuclides were each less than 6
20
-------
SECTION 7
OPEN PIT COPPER MINE AND CONCENTRATOR
PROCESS DESCRIPTION
A large open-pit copper mine and the associated mill and concentrating
plant were surveyed to further characterize the copper industry radioactivity
emissions. At the time of the survey the pit covered an area of about 2250 by
1700 m and had reached a depth of about 550 m. The mine operators removed
about 158,000 MT of material per day, of which about 45,300 MT were ore.
Ore and rock were blasted each day at noon. Ore trucks operated around
the clock hauling ore to the crusher or leach screening pile and rock to the
waste dump. Ore which graded 0.24 percent copper or higher was sent to the
crusher. That which graded 0.10 to 0.23 percent went to the leach screening
pile where copper was chemically leached from the ore. Rock grading less than
0.10 percent was waste rock. A baghouse controlled particulate emissions at
the crusher and truck hopper. Vibrating grizzly feeders screened the crushed
ore at 4 inches. Oversize is sent to a gyratory primary crusher. Undersize
and crushed ore were moved by conveyor belt to an open coarse ore stockpile or
to six coarse ore storage bins. "Chem-Jet" sprays were used to suppress dust
formation after the grizzlies, at the entrance to the primary crusher, and at
the crusher discharge. A baghouse identical to the one on the truck hopper
collected dust from all primary crusher operations.
"Chem-Jet" sprays and hoods connected to the baghouse controlled dust from
transfer points on the conveyor from the primary crusher to storage. Similar
controls collected dust from transfer and discharge points on the conveyor
system from coarse ore storage to six surge bins at the secondary crusher.
Vibrating screens separated ore from the surge bins at 1 inch (2.5 cm)
with undersize going directly to 12 fine ore storage bins at the concentrator
building. Oversize was crushed to 3/4-inch (2-cm) size in three gyratory
crushers and sent to fine ore storage. Transfer points were hooded and the
dust was collected by six Ducon wet scrubbers. Chem-Jet spray systems also
controlled dust at belt transfer points.
A system of belts carried ore from the 12 fine ore bins to six rod mills.
Twelve ball mills, operating in a closed circuit, further ground the ore from
the rod mills. A cyclone and flotation section recovered mineral values from
the pulverized ore. Sand tailings were thickened and pumped 4.8 km (3 miles)
to the tailings pond. Wet concentrates were carried by rail to the smelter.
Seven Ducon scrubbers collected dust from the fine ore bins area. Roof fans, a
21
-------
wall fan, and natural ventilation provided ventilation for the concentrator
building. The entire process of milling, flotation, and concentration was
carried on under one roof. The process was wet and generated no appreciable
airborne particulates. Water decanted from the tailings pond was recvcled tn
be used as flotation spray water.
SAMPLING POINTS
Ambient suspended particulate and radon samples were collected at three
locations around the facility. One ambient site, identified as Mountain Con
was about 0.8 km northwest of the mine pit, 2.9 km northwest of the concen-
trator. The second site, Alpine, was about 270 m southeast of the concentrator
building and 1.9 km southeast of the mine center. The third site, Kaw Avenue
?JSi, 1.1 u* ,km southwest of ^e mine pit and concentrator. Continuous
24-hour high volume particulate samples were collected simultaneously with all
plant emission radon samples. Sufficient samples were collected to assure at
least two samples from each 4-hour period of the day. Measurements of radon
emanation from the surface were made in the mine pit and from surrounding
areas by charcoal canisters.
+h ISP ,an? Slze-fractionated particulate emission samples were collected from
the truck hopper and primary crusher exhausts. Company data and visual exami-
nation indicated that other possible controlled sources would be insignificant
compared to those two.
Emissions of radon were measured from the truck hopper, primary crusher
secondary crusher, and concentrator handling exhausts.
Size-fractionated suspended particulate samples were collected adjacent to
the coarse ore storage pile and the leach screening pile.
SAMPLE RESULTS
TRd,ii0antlVrty concentrations in ore, concentrates, and tailings are shown
J * Jf Concentrations in ore of uranium and thorium chain nuclides are
J««J- 5T *JjeLthe avera9e ejected in crustal rock. As in the mill process
JSSfnfSS/lS *5* ^!r2rou"d C0pper mlne» tne radioactivity levels in
T KiRa1Sn Concentrat1ons measured at the three ambient stations are shown in
3 1? u "?ur]y average wind directions were evaluated to determine if the
station had been upwind, downwind, or crosswind from the open mine pit durina
each sampling period. In only three cases was it determined that a station
had been downwind. Although diurnal variations are quite evident, with the
highest concentrations during the early morning hours and lowest concentrations
downwind 0VtheemTn°en: "° '^ "" °bSerVed " * r6SUlt °f be1ng Upw1nd or
22
-------
TABLE 10. OPEN PIT COPPER MINE AND CONCENTRATOR PROCESS SAMPLE RADIOACTIVITY
Radioactivity Concentrations (pCi/g)
ro
CO
Sample
U-238
U-234
Th-230
Ra-226
Pb-210
Po-210
Th-232
Th-228
Ore-Primary Crusher
Ore- Secondary Crusher
Ore Average
Concentrate
Concentrate Average
Tailings
Tailings Average
2.4
2.0
2.2
2.0
2.2
1.1
1.7
1.4
1.5
1.7
1.7
1.6
± 0.3
* 0.4
± 0.5
± 0.3
± 0.3
* 0.3
* 0.4
* 0.3
* 0.3
* 0.3
* 0.3
± 0.2
2.2
1.9
2.2
1.4
1.9
1.2
1.6
1.4
1.5
1.5
1.7
1.6
± 0.3
* 0.4
± 0.5
± 0.2
± 0.3
* 0.3
* 0.3
* 0.2
± 0.3
* 0.3
± 0.3
* 0.2
3.6
6.7
3.8
2.4
4.1
2.0
3.4
2.7
3.2
4.3
2.3
3.3
± 0.9
* 1.7
± 1.4
± 0.8
± 0.8
± 0.8
± 1.1
* 0.7
* 1.4
± 1.5
± 0.9
* 0.8
0.92
1.5
0.42
0.72
0.89
0.14
0.93
0.54
1.0
1.6
1.0
1.2 *
* 0.28
± 0.4
± 0.13
* 0.21
± 0.12
* 0.04
* 0.28
* 0.14
* 0.3
* 0.4
± 0.3
t 0.2
7.2 ± 2.7
4.7 ± 1.5
2.6 ± 1.3
2.0 ± 1.3
4.1 * 0.9
<2.3
2.6 * 1.5
<2.5
2.1 * 1.4
<6.6
2.2 * 1.4
<3.6
6.3
5.0
3.5
3.3
4.5
<]
2.2
<1
2.0
2.0
2.8
2.3
± 1.6
± 1.5
* 1.3
* 1.3
± 0.9
..2
* 1.1
..7
* 1.1
± 1.1
* 1.2
* 0.7
2.5
4.2
3.5
2.0
3.1
1.3
0.82
1.1
3.7
4.2
1.2
3.0
± 0.7
± 1.2
± 1.0
± 0.7
* 0.6
± 0.6
* 0.46
± 0.4
± 1.6
± 1.4
* 0.6
* 0.7
3.5
4.5
3.8
1.5
3.3
0.94
1.0
0.97
4.9
4.2
1.1
3.4
± 1.2
* 1.4
* 1.2
± 0.6
± 0.7
± 0.40
± 0.4
± 0.3
± 1.5
* 1.4
* 0.4
* 0.7
a) Picocuries (10~^ curies) per gram plus or minus twice the standard deviation based on counting statistics.
-------
TABLE 11. AMBIENT STATION RADON-222 CONCENTRATIONS - OPEN PIT COPPER MINE
Date
10/14/80
Time
1200-1500
1600-1900
2000-2300
Radon-222 Concentration (nCi/m3)a
Kaw Avenue Alpine Mt. Con
0.53 ± 0.07 (U)b
0.21 ± 0.06 (C) 0.20 ± 0.06 (C)
0.30 ± 0.07 (C) 0.32 ± 0.06 (C)
0.63 ± 0.7 (C)D
<0.07 (U)
0.28 ± 0.05 (U,D)
10/15/80
0300-0600
1200-1500
1600-1900
1.1 ± 0.1 (U,C)
0.44 ± 0.06 (U)
1.3 ± 0.1 (D,C)
0.22 ± 0.05 (C)
0.09 ± 0.05 (C)
0.32 ± 0.05 (U,C)
0.20 ± 0.05 (C)
10/16/80 0700-1000 0.57 ±0.04 (NA)
1200-1500
1600-1900
0.10 ± 0.04 (C)
0.16 ± 0.05 (U)
0.69 ± 0.09
0.95 ± 0.09
0.82 ± 0.06 (NA)
0.12 ± 0.05 (U)
0.08 ± 0.03 (C)
0.55 ± 0.04
0.77 ± 0.11
0.66 ± 0.06 (NA)
0.23 ± 0.06 (C)
10/17/80
0000-0300
1200-1500
0.81 ± 0.06 (C)
0.14 ± 0.02 (U)
1.2 ±0.1 (U)
0.19 ± 0.02 (C)
0.83 ± 0.08 (D)
0.28 ± 0.03 (C)
a) Nanocuries (10~9 curies) per cubic meter plus or minus twice the
standard deviation based on counting statistics.
b) Upwind (U), downwind (D), or crosswind (C) from the open pit mine,
based on hourly average wind observations at Mt. Con site. NA = not
available due to recorder failure.
24
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TABLE 12. COPPER MINE CRUSHER AND CONCENTRATOR - RADON-222 MEASUREMENTS
Collected Concentrations (nCi/m )
Source
Primary
Time
1422-1706
0300-0600
1200-1500
Date Gross
10/14/80
10/15/80
10/17/80b
0
0
0
.62
.90
.66
± 0.
± 0.
* 0.
08
09
03
Primary Crusher Average
0
-0
0
0
Net
.46
.20
.46
.24
± 0.
± 0.
± 0.
* 0.
Annual
Emissions(Ci/Yr)
11
13
08
38
0.22
Secondary 1435-1752 10/14/80 0.45 ±0.08
1225-1538 10/15/80 0.26 ± 0.07
Secondary Crusher Average
Total for seven stacks
0.29 ± 0.11
0.06 * 0.10
0.18 ± 0.16
0.077
0.50
Truck
1630-1903 10/15/80
1154-1412 10/16/80
1514-1819 10/16/80b
Truck Hopper Average
0.36 ± 0.06
0.74 ± 0.06
0.35 ± 0.03
0.25 ± 0.08
0.63 ± 0.06
0.23 * 0.07
0.37 ± 0.23
0.31
Concentrator 1106-1419 10/14/80° 1.1 ± 0.1
1140-1505 10/15/806 0.45 ± 0.05
1519-1825 10/15/80 0.25 * 0.06
Concentrator Bldg. Ventilator Avg.
0.57 ± 0.12
0.16 ± 0.14
0.16 ± 0.14
0.30 ± 0.24
0.86
a) Nanocuries (10~ curies) per cubic meter plus or minus twice the
standard deviation based either on counting statistics or sample variance
for source averages.
b) Derived from duplicate samples.
c) 144-hour per week operation.
25
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Radon concentrations and emission rates determined for the stacks ™H
building surveyed are given in Table 12. Each of the sources showed average
radon concentrations which were above the ambient levels determined from the
ambient stations. The maximum net concentration observed was 0 37 ± 0 23
new in the truck hopper exhaust. The maximum annual emission rate for a
single source was 0.86 Ci/y from the concentrator building. Total radon
emissions from the crusher and concentrator operations was 1.9 Ci/y.
Concentrations of uranium-234 and uranium-238 in stack emissions averaged
0.2 pCi/rrP from the primary crusher and 0.09 pCi/m3 from the truck hopper
These compare to measured ambient concentrations of about 0 5 fCi/m3
Annual emissions measured from the primary crusher and truck hopper were less
than 1 mCi (Table 13).
TABLE 13. AVERAGE ANNUAL EMISSIONS FROM AN OPEN PIT COPPER MINE
Source
Primary
Crusher
Truck Hopper
U-238
0.24
0.07
U-234
0.24
0.14
Th 230
<0.3
<0.3
Ra-226
0.11
0.07
Pb-210 Po-210 Th-232
0.89 <1
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Measurements of radon emanation rates from the surface of the mine and
surrounding areas are summarized in Table 15. Several canisters in the mine
were lost due to mining activities, but those that were collected show an
increase in emanation rates as a function of depth. This may be real or may
result from infiltration of radon from the surrounding air. Radon would be
expected in higher concentrations near the bottom of such a pit, whether
natural or man-made. The difficulty of sealing canisters to the rocky mine
surfaces could have allowed some infiltration. In general, the emanation rate
from a rock surface would be less than from soil because of the lower porosity
of rock. Radon emanation rates from the area east of the pit are comparable to
the reported national average for U.S. soils of 35 pCi/m^-min (4). The
highest radon emanation rate was measured from a reportedly undisturbed soil
area northwest of the mine. High radon emanation rates in the area are
believed to be due to a combination of extensive underground mining, cracks in
the earth structure, and the high mineralization of the area.
TABLE 15. OPEN PIT COPPER MINE RADON EMANATION RATES
Emanation Rates (pCi/m -min)a
Mine Pit (In Order East of Pit (In Order NW of Pit (In Order
of Increasing Depth) of Increasing Distance) of Increasing Distance
2.3 15
14 25 100
4.5 35 170
26 1.2 120
130 39 24
a) Picocuries (10"12 curies) per square meter per minute.
27
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REFERENCES
1. National Council on Radiation Protection and Measurements. Natural
Background Radiation in the United States, NCRP Report No. 45, Washington,
D.C., 1975.
2. Code of Federal Regulations, Title 40, Chapter 1, Part 60, Appendix A.
3. Code of Federal Regulations, Title 40, Chapter 1, Part 50, Appendix B.
4. Turekian, Karl K., Y. Noyaki, and Larry K. Benninger, Geochemistry of
Atmospheric Radon and Radon Products, Annual Review of Earth and
Planetary Sciences, 5:227-255, Palo Alto, California, 1977.
5. Polanski, A. Geochemistry of Isotopes, TT61-31327 (Engl. Transl.)
Scientific Publ. Foreign Coop. Center, Warsaw, Poland, 1965.
28
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
NO.
EPA-520/6-82-018
2.
AND SUBTITLE
Emissions of Naturally Occurring Radioactivity
from Aluminum and Copper Industries
6. PERFORMING ORGANIZATION CODE
8. PERFORMING ORGANIZATION REPORT NO.
Vernon E. Andrews
3. RECIPIENT'S ACCESSION NO.
REPORT DATE
Movereber 19S2
PERFORMING ORGANIZATION NAME AND ADDRESS
U.S. Environmental Protection Agency
Office of Radiation Programs-Las Vegas Facility
P.O. Box 18416
Las Vegas, Nevada 891H
1O. PROGRAM ELEMENT NO.
11. CONTRACT/GRANT NO.
SPONSORING AGENCY NAME AND ADDRESS
13. TYPE OF REPORT AND PERIOD COVERED
Same As Above
14. SPONSORING AGENCY CODE
-^SUPPLEMENTARY NOTES
1 'This is the sixth
to the 1 977 Clean
in a series of reports
Air Act Amendments
covering work performed in response
^ABSTRACT
This report summarizes five surveys which were conducted at a Bauxite mining
operation, an Alumina reduction plant, an Aluminum reduction plant, an underground
Copper mine and mill, and an open pit Copper mine and concentrator. Process
components and controlled source releases were sampled for naturally occurring
radioactivity. Particular emphasis was given to Radon-222, Lead-210, and
Polonium-210 emissions from crushing and drying processes.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
Natural Radioactivity
Airborne Wastes
Exhaust Gases
Underground Mining
Beneficiation
Tailings
-5lSTHIBUTIONi,IATEMENT
Release to Public
Technologically
Enhanced Radioactivity
19, SECURITY CLASS (ThisReport)
Unclassified
20. SECURITY CLASS iThis page)
Unclassified
COSATI Field/Group
1808
1302
2102
1308
21. NO. OF PAGES
28
22. PRICE
V. 4-77) PREVIOUS EDITION IS OBSOLETE
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