United St.
Environmental Prot
Age i
Office of Radiation Programs
Las Vegas Facility
PO Box 18416
Las Vegas NV 891 14
EPA 520 6-82-020
November 1982
Radiation
Emissions Of Naturally
Occurring Radioactivity:
Underground Zinc
Mine And Mill
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EPA-520/6-82-020
November 1982
EMISSIONS OF NATURALLY OCCURRING RADIOACTIVITY
UNDERGROUND ZINC MINE AND MILL
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 63-02-2815
Office of Radiation Programs - Las Vegas Facility
U.S. Environmental Protection Agency
Las Vegas, Nevada 89114
DISCLAIMER
This report has been reviewed by the Office of Radiation Programs - Las
Vegas Facility, U.S. Environmental Protection Agency, and approved for publi-
cation. Mention of trade names or commercial products constitutes neither
endorsement nor recommendation for their use.
ii
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PREFACE
The Office of Radiation Programs (ORP) of the U.S. Environmental
Protection 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 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 radioactivity 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
Las Vegas Facility
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CONTENTS
Page
PREFACE
LIST OF FIGURES ............................. vi
LIST OF TABLES .............................. vi
I. BACKGROUND ............................. !
II. INTRODUCTION ............................ 2
III. SUMMARY .............................. 3
IV. MINE OPERATIONS .......................... 3
V. MILL OPERATIONS .......................... 4
VI. SAMPLING LOCATIONS AND PROCEDURES ................. 6
A. Site Selection ......................... 5
B. Sampling Techniques ....................... 6
C. Sample Analysis ......................... 8
D. Data Reporting ......................... H
VII. SAMPLE RESULTS ........................... 12
A. Process Samples ......................... 12
B. Ambient Air Samples ........ . .............. 12
C. Mine and Mill A1r Samples .................... 15
1. Mine Emission Samples .................... 15
2. Mine Working Level Measurements ............... 18
3. Mill Emission Samples .................... 19
VIII. POPULATION DISTRIBUTION ...................... 20
IX. DISCUSSION OF RESULTS ....................... 23
X. REFERENCES ............................. 25
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LIST OF FIGURES
Number
Page
1 Schematic of Friedensville Mine and Mill Operation 7
2 Friedensville Mill Plot Diagram 9
3 Friedensville Mill Tailings Plot Diagram 10
4 Map of Friedensville Mine and Mill with Surrounding Area 24
LIST OF TABLES
Number
Page
1 Process Sample Radioactivity Concentrations 13
2 Ambient Radon-222 Concentrations 14
3 High Volume Air Sampler Results 16
4 Radon-222 Emissions from Mine and Mill 17
5 Mine Working Level Measurements 19
6 Estimated Annual Radioactivity Emissions 21
7 Radon-222 Flux from Soil and Tailings 22
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I BACKGROUND
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 signifi-
cant quantities are those in the uranium-238 and thorium-232 decay series.
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 approximately
1.8 ppm (0.6 pCi/g) and 9 ppm (1 pCi/g) respectively (NCRP, 1975).
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 the soils and rocks.
Because mining and milling operations involve large quantities of ore, and
because there was 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 get statistically
significant results.
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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.
II INTRODUCTION
The Mine Safety and Health Administration (MSHA) makes periodic measure-
ments of radon daughter working levels (WL)* in underground mines. Zinc mines
are included among those having the highest measured WL (Goodwin, 1978). The
Office of Radiation Programs (ORP) selected the zinc industry for inclusion in
this study because of the potential for releases of radioactivity indicated by
the radon daughter concentrations. Only 45 underground mines were found to
have radon daughter concentrations in excess of 0.1 WL during 1976 and 1977.
Seven of these were zinc or lead-zinc. The Friedensville mine, with an average
reported radon daughter concentration of 0.58 WL near the portal, had the
fourth highest concentrations during that period.
Engineering-Science (E-S) performed the sample collection and emission
measurements under contract to EPA. E-S has reported their results separately
(Engineering-Science, 1978). ORP, E-S, and MSHA representatives visited the
Friedensville mine and mill for familiarization and to select appropriate
sampling sites.
E-S conducted the sampling and measurement program during the week of
September 25-29, 1978. The author accompanied E-S on the survey and performed
the WL measurements in the mine. In addition to sample collection, E-S
installed a temporary meteorology station on the tailings pile to measure wind
speed and direction. Eberline Instrument Corporation (EIC) did the radio-
logical analysis of the samples.
*The WL is defined as any combination of shortlived radon daughter products in
5
1 liter of air that will result in the ultimate emission of 1.3 x 10 meV of
potential alpha energy (U.S. Public Health Service Publication No. 494, 1957)
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E-S described the sample collection and reported the parameters measured,
including sample volumes and discharge point air flow rates. This report
combines the data from radiological analyses with data reported by E-S to give
the radionuclide concentrations and rates of discharge.
Ill SUMMARY
The zinc mine and mill at Friedensville, Pennsylvania was chosen because
of its high production rate and the high WL measurements reported by MSHA.
Participate and gaseous emission samples were collected from all important
emission points and radon flux measurements were made on the mill tailings.
Radon-222 was the only radionuclide definitely measured above ambient levels
from any emission point. It was determined that the mine exhausts approxi-
mately 230 Ci/y of radon while the radon from the mill totals less than 1
Ci/y. The radon flux from the tailings pile was found to be approximately
one-third of that from the native soil. The reduction in radon flux from the
soil surface as a result of being covered by the tailings piles about offsets
the radon generated by the mill.
Natural radioactivity concentrations in the ore and process samples were
below the average values normally observed in limestone, which makes up the
bulk of the ore. The most likely explanation for the high radon concentra-
tions observed in the mine exhaust is the large quantity (110 nP/min) of
water which flows into the mine. A water sample collected at the surface
discharge from the mine had a radon-222 concentration of 50 pCi/1. This was
probably a few percent, at most, of the original concentration in water
entering the mine.
IV MINE OPERATIONS
The Friedensville mine ore is amorphous zinc sulfide (a form of
sphalerite) in a limestone matrix. The ore runs approximately 6 percent zinc.
Friedensville has a history of zinc mining; several small open pit zinc mines
had been operated in the vicinity during the past century, and in 1958 New
Jersey Zinc Company opened the underground Friedensville Mine.
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The mine is a room and pillar operation with 10 levels in use at the time
of the survey. A single vertical shaft provides for personnel access, ore
removal via two skips, and inflow of ventilation air. An incline connecting
all levels exits through one of the old open pit mines and provides a route
for loaders and trucks to move ore. A series of dampers and air locks con-
trols air flow through the mine. This system not only assures ventilation of
all actively worked areas, but also prevents unnecessary air movement through
unused mine areas. Ventilation air exhausts through the incline portal at the
bottom of the open pit mine.
Ore mined on the various levels is hauled to ore passes where it falls to
the primary crusher located 585 m (1920 feet) below the surface. The ore is
crushed to a size of approximately 7.5 to 13 cm (3 to 5 inches) and is hauled
to the surface in 6-1/2 ton capacity skips.
The Friedensville mine is reported to be the wettest mine in the western
hemisphere; considerable infiltration of water occurs at all levels. Water is
carried by open drains to sumps and is pumped through a series of water raises
to the surface, receiving considerable aeration on the way. On the surface,
water passes through two lagoons to permit settling of solids before being
discharged to Saucon Creek. Water flow rates were 110 m3/min (29,000 gpm)
at the time of the survey.
Mining was conducted around the clock with the exception of the second and
third shifts (3:00 p.m. to 7:00 a.m.) on Sundays and holidays. Three ore
faces were worked simultaneously. Two or three faces were blasted each shift,
generally during lunch or at the end of a shift.
V MILL OPERATIONS
Ore carried to the surface in the skips is dumped into a skip bin. Ore
from the skip bin is screened at 2.2 cm (7/8 inch) with oversize going to a
secondary crusher. Airborne particulates generated during ore transfer,
screening, and secondary crushing, are drawn through a Rotoclone emission
control and vented through a 35.6- by 45.7-cm (14- by 18-inch) duct above the
roof of the secondary crusher. The exhaust is approximately 6 m (20 feet)
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above ground level. Undersize from the 7/8-inch screen and crushed ore from
the secondary crusher are conveyed to an ore bin. Ore from the bin is
screened at 0.95 cm (3/8 inch) and oversize goes to a tertiary crusher.
Crushed ore from the tertiary crusher and undersize ( 3/8 inch) are carried by
bucket elevator to a surge bin which feeds two identical concentrating
processes identifed as "East" and "West." Airborne particulates produced
during screening, tertiary crushing, and ore transfer via the bucket elevator
are controlled by a Rotoclone. The Rotoclone discharges through a 36.2- by
47.6-cm (14.25- by 18.75-inch) stack approximately 21 m (70 feet) above the
ground.
The ore in each concentrating process passes through a rod mill then
through a classifier. Sands from the classifier are further ground in a ball
mill and returned to the classifier. Both processes are conducted wet and
generate negligible airborne particulates. Conditioners are added to the
aqueous slurry from the classifier overflow which is then processed by a
series of flotation cells.
The final zinc sulfide concentrate resulting from the East and West con-
centrating processes is combined and concentrated on a seven-unit disk filter.
From there it passes through a dryer to storage. Airborne particulates from
the dryer are collected and passed through a Rotoclone which discharges
through a 45.4-cm (17.9-inch) diameter stack approximately 17 m (55 feet)
above ground.
The tailings produced are basically a clean, fine limestone sand. About
15 percent of the tailings are processed by hydroclones to produce "spigot", a
damp sand product. Ten to 15 percent of the spigot product is dried, size
classified, and stored in silos to be bagged or sold as bulk agricultural
limestone. The rest of the spigot product is mixed with cement to be used for
mine fill or is sold as damp bulk limestone. The tailings not used or sold
are pumped as a slurry to tailings piles about one-half mile north. Some
limestone is also removed from the tailings piles and sold as agricultural
limestone. Airborne particulates generated during limestone drying are
controlled by means of a packed scrubber discharging through a 50.8-cm
(20-inch) diameter stack approximately 15 m (50 feet) above ground. The silo
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loading system is also a generator of airborne particulates. These are
controlled by a hydrofilter atop the silo. Discharges from the hydrofilter
are through a 61-cm (24-inch) diameter stack about 18 m (60 feet) above
ground. Figure 1 is a schematic of the Friedensville operation from primary
crusher through shipment of the concentrate product.
Mill operation is continuous except for the first shift (7:00 a.m. to 3:00
p.m.) Mondays when it is shut down for maintenance. The secondary crusher
operates during the second and third shift daily except Sunday. The limestone
drying and silo loading systems operate only as needed, approximately 650
hours per year.
VI SAMPLING LOCATIONS AND PROCEDURES
A. Site Selection
E-S and EPA personnel determined sampling locations and types of samples
to be collected during their pre-survey visit. Air sampling locations
selected were:
1. Mine ventilation exhaust (mine portal)
2. Secondary crusher Rotoclone exhaust
3. Tertiary crusher Rotoclone exhaust
4. Mill building fugitive emissions (powered roof vent)
5. Concentrate dryer Rotoclone exhaust
6. Linestone dryer scrubber exhaust
7. Silo loading system hydrofilter exhaust
8. North side of old tailings pile, "A"
9. Radon flux from tailings piles and "undisturbed" soil
10. Background (ambient) air samples between mill and mine portal
(pump house)
11. Background (ambient) air samples at north side of mill
B. Sampling Techniques
Most samples were collected using EPA reference methods (40 CFR 60).
Stack sampling points were selected according to EPA Method 1. Stack gas
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TAILS
1
TAILS TO
HYDROCLONE
LEGEND
-*s Material Flow
Air Flow
Emission Sample Point
Process Step
Figure 1. Schematic of Friedensville Mine and Mill Operation.
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velocity and volumetric flow rate were determined by EPA Method 2. Gas
samples for radon analysis were collected using EPA Method 3. Particulate
emissions from the crusher and concentrate dryer stacks were determined using
EPA Method 5. Stack samples for particle size distribution were collected
with an Anderson cascade impactor using EPA Method 5. High volume airborne
particulate samples were collected in accordance with the Reference Method for
the Determination of Suspended Particulates in the Atmosphere (High Volume
Method) (40 CFR 50). Size-fractionated high volume particulate samples were
collected with a Sierra high volume cascade impactor head.
Figure 1 shows the sampling points related to process steps. Figures 2
and 3 are plot drawings of the mill and tailings areas showing the sampling
point locations. Gaseous samples for radon analysis were collected from all
sampling locations. Samples for total suspended particulates (TSP) were
collected from all locations except the roof monitors, limestone dryer, and
silo loading system. Size-fractionated particulate samples were collected
from the Rotoclone exhausts on the secondary and tertiary crushers, on the
concentrate dryer, at the mine exhaust, and on the tailings pile. Process
materials were sampled at several points so that emissions could be related to
the material involved.
C. Sample Analysis
E-S made mass determinations for TSP and size-fractionated samples before
forwarding the samples to EIC for radiochemical analysis. Gas (whole air)
samples to be analyzed for radon-222 were shipped to EIC for arrival within 24
hours of collection. Process samples and airborne particulates on filters
were analyzed by complete dissolution of the samples and separation of the
elements of interest by chemical techniques. The separated uranium and
thorium elements were counted on alpha spectrometers for individual isotopic
quantisation. An alpha scintillation counter measured the polonium-210
activity. 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
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SAUCON VALLEY ROAD
CORN F I l)
TAILINGS
PILE ROAD
PLANT
ACKGROUND
GAS SAMPLE
SECONDARY CRUSHE
TERTIARY CRUSHER
ROOF MONITOR
CONCENTRATE DRYER
LIMESTONE DRYER
SILO LOADING SYSTEM
.
MINE COLLAR!
MINE WATER
DISCHARGE
SEWAGE TREATMENT
V
SAUCON CREEK
PARKING
LOT
LAGOON
LEGEND
Radon Flux Sampler Site
Figure 2. Friedensville Mill Plot Diagram.
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NEW TAILINGS PILE "B"
in i ii"'/,
OLD TAILINGS ''••
PILE "A"
HI VOLS AND
GAS SAMPLER
GASOLINE GENERATOR
Q-PUMP HOUSE
0-r
HI VOL AND
GAS SAMPLER
BACKGROUND
STATION
TAILINGS
PILE ROAD
MILL APPROX
1500' SOUTH
-N-
PORTAL ROAD
SAUCON VALLEY ROAD
LEGEND
Boundary of Old
Tailings Pile
Boundary of New
Tailings Pile
Location of Radon
Flux Samplers
Location of Hi-Vols
Location of Met.
Station
SCALE 1cm.
50 m.
Figure 3. Friedensville Mill Tailings Plot Diagram.
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quantitate lead-210. Radium was separated and enclosed as a solution in a
sealed tube to allow for ingrowth of radon-222 from radium-226. After 3 weeks
of ingrowth the radon gas was evolved and collected in an alpha scintillation
cell. After allowing the radon daughter products to ingrow for several hours
the cell was counted to quantitate radon-222. Whole air samples for radon
analysis were transferred to alpha scintillation cells and counted in the same
manner as radon from the radium analysis. Activated charcoal canisters placed
on the surface of the tailings piles and background locations measured the
radon flux. The canisters were left in place for the duration of the survey
and were shipped by air express to the EPA Eastern Environmental Radiation
Facility in Montgomery, Alabama for analysis of radon decay products by gamma
spectrometry. This analysis permitted a calculation to be made of the
radon-222 flux (emission rate per unit area) from the surface.
D. Data Reporting
The radioactivity reported for each sample, except for charcoal canisters,
is the net radioactivity plus or minus twice the standard deviation (2s). The
net radioactivity is the gross sample radioactivity minus counter background,
and for filter samples, minus an average value for the radioactivity content
of a blank filter. 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 than zero. Of course, there is no negative radio-
activity. In these cases, as with all others, the net result must be
considered along with the 2s uncertainty.
In some cases ambient radon samples are reported with negative concentra-
tions. When those results were algebraically subtracted from effluent samples
the net concentration was greater than the gross sample. Here, again, the net
result must be evaluated with the resultant 2s uncertainty.
11
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VII SAMPLE RESULTS
A. Process Samples
Ore from the secondary crusher, dried zinc sulfide concentrate, dried tail-
ings from the dryer, and wet tailings composited from the new tailings pile
were sampled. Analytical results are shown in Table 1. The radioactivity con-
centration of 0.18 +_ 0.08 pCi/g of uranium-238 in ore, with similar results
for other radionuclides in the decay chain, is equivalent to 0.6 ppm of uranium
in the ore. This concentration is at the low end of the range of observed
uranium concentrations in limestone.
The only consistent differences in radioactivity concentrations in process
samples occur with radium-226. The results in Table 1 indicate that the
concentrating process discriminates against radium, with the result that the
isotope is depleted in the concentrate and enriched in the tailings. This may
only be the result of analytical or sample variability. A sample of concen-
trate produced by the Friedensville mill was collected at the New Jersey Zinc
facility at Palmerton, New Jersey as part of a group of 10 samples from mills
in the United States, Canada, and Mexico. The Friedensville sample had
uranium-238 and radium-226 concentrations of 0.23 _+ 0.09 and 0.48 _+ 34 pCi/g.
Radium-226 concentrations in the other samples did not differ significantly
from uranium-238 concentrations. Even at the level of 0.2 to 0.24 pCi/g found
in tailings the final radium-226 concentration is on the low side of the
natural range in limestone. The difference between thorium-230 concentrations
in ore and the new tailings pile is considered to be only an analytical
effect, as the concentration in dried tailings did not differ significantly
from ore.
B. Ambient Air Samples
Ambient radon-222 concentrations at the two background stations were
measured over 3-hour periods from September 25 to 28. The results are shown
in Table 2. Wind measurements reported by E-S were examined to determine if
emissions from the mine portal had any influence at the background stations.
Only one ambient sample was collected during a period when the wind direction
would indicate an effect by mine emissions. Using a Gaussian plume diffusion
12
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TABLE 1. PROCESS SAMPLE RADIOACTIVITY CONCENTRATIONS
Sample Type
Ore from
Secondary Crusher
Zinc Sulfide
Concentrate
U-234
0.18 ± 0.09
0.16 ± 0.03
U-238
0.18
0.16
± 0.08
* 0.03
Th-228 Th-230 Th-232
0.05 ± 0.02 0.15 =
0.04 ± 0.02 0.13 *
t 0.04 0.08 ± 0.03
t 0.04 0.04 ± 0.02
Ra-226
0.11 =
0.06 ;
' 0.01
t 0.01
Pb-210
0.48 ± 0.32
-0.13 ± 0.96
Po-210
0.23 * 0.09
0.19 ± 0.09
Dried Tailings 0.16 ± 0.06 0.13 * 0.06 0.02 ± 0.01 0.13 * 0.03 0.03 * 0.01 0.20 ± 0.01 0.23 ± 0.33 0.17 * 0.08
New Tailings Pile 0.18 * 0.05 0.16 * 0.04 0.06 * 0.01 0.30 ± 0.07 0.07 ± 0.02 0.24 ± 0.02 0.32 ± 0.29 0.15 * 0.08
a} Picocuries (10~12 curies) per gram of material, plus or minus twice the standard deviation based on counting results only.
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Location
Pump House
Pump House
Pump House
Pump House
Pump House
Pump House
Pump House
Plant
Plant
TABLE 2.
Date
9/25
9/25
9/25
9/26
9/26
9/26
9/27
9/28
9/28
AMBIENT RADON-222 CONCENTRATIONS
Time
On - Off
0800 -
1100 -
1600 -
0100 -
0800 -
1600 -
0100 -
0830 -
1131 -
1100
14003
1900
0400
1100
1900
0400
1130
14313
Radon Concentration
(nc/nr)b
0.42
0.04
-0.02
-0.02
-0.01
0.18
0.84
0.68
0.07
± 0.14
± 0.07
± 0.22
± 0.34
± 0.10
± 0.26
± 0.44
± 0.30
± 0.14
a) Calculated from duplicate samples
b) Nanocuries (10~ curies) per cubic meter plus or minus twice
the standard deviation based on counting results only
14
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model with Pasquill's diffusion categories (Slade, 1968) for the period of
0800 - 1100 hours on September 26 an expected concentration of 0.06 nCi/m
was calculated. This was within the range of the reported concentration of
-0.01 + 0.10 nCi/m .
Examination of the data showed a possible correlation between radon concen-
trations and wind speed. Radon concentrations were compared to average wind
speeds duing the sampling periods. An inverse relationship was obtained
between wind speed and radon concentration, but the correlation co-efficient
was not significant at the 5 percent confidence level. A correlation was also
sought between radon concentrations and the average wind speeds during the
3-hour period preceding sample collection. The first sample was excluded
because the meteorology station had not been put into operation that early. An
inverse correlation was again obtained. The correlation coefficient was large
enough to reject the hypothesis that no correlation existed at the 5 percent
level of significance. The conclusion is that the varying radon concentrations
were a function of the varying wind speeds, with higher concentrations during
periods of lower wind speeds. This is an expected result (NCRP, 1975).
E-S used high volume air samplers to collect samples of airborne particu-
lates at the pump house background station shown in Figure 3. High volume air
sampler results are shown in Table 3.
C. Mine and Mill Air Samples
1. Mine Emission Samples
Seven gas samples for radon analysis, plus one set of duplicate samples
for quality assurance, were collected at the mine portal exhaust. At least
two samples were collected during each working shift in the mine. Concentra-
tions measured over the 3-hour sampling periods ranged from 56 to 93 nanocuries
3 3
per cubic meter (nCi/m ) with an average of 71 nCi/m . No significant
difference was observed between the average concentrations measured during the
three work shifts. E-S measured the air flow rate of 6230 m /min. This
results in an annual discharge of 230 Ci. Sampling results are summarized in
Table 4.
15
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TABLE 3. HIGH VOLUME AIR SAMPLER RESULTS
Time-Cate Radioactivity Concentration (fc1/m3)a
Location Collected U-238 U-234 Th-230 Ra-226 Pb-210 Po-210 Th-232 Th-228
Pump House 1115 - 9/25 0.37 * 0.32 0.66 * 0.42 0.06 * 0.54 -0.33 * 0.66 310 ±7 260 ± 38 -0.16 ± 0.31 -0 12 * 0 22
Station 1115 - 9/26
Pump House 1402 - 9/27 0.06 * 0.12 -0.02 * 0.14 0.21 * 0.33 0.09 * 0.33 28 * 3 19 * 12 0 12 ± 0.22 0 36 * 0 27
Station HOO - 9/29
Old Tailings 1402-9/27 -0.003*0.088 0.05*0.16 -0.09*0.26 -0.15*0.35 4.4*2.2 13 * 5 -0.08 ± 0.16 -006*011
Pile 1410 - 9/29
Mine Portal 1203 - 9/26 -0.08 * 0.63 -0.61 * 0.74 -0.58 * 2.2 2.5 * 2.8 380 ± 30 430 * 80 -0.7 ± 1.3 -0 51 * 0 89
-• 1751 - 9/26
CT)
a) Femtocuries (10~^^ curies) per cubic meter, plus or minus twice the standard deviation based on counting results only.
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Source
Secondary^
Crusher
Tertiary6
Crusher
Concentrate6
Dryer
TABLE 4. RADON-222
Time Date
1630-1930
0100-0400
1215-1500
0100-0400
1215-1500
0835-1135
9/25
9/27c
Source
9/25
9/26c
Source
9/25
9/28c
Source
EMISSIONS FROM MINE AND MILL
Concentration (nCi/m?) Annual
Gross Net Release Ci/yr
0.24*0
1.18*0
Average
-0.02±0
0.27*0
Average
-0.03*0
0.86*0
Average
.18
.24
.10
.13
.10
.23
0
0
0
-0
0
0
-0
0
0
.26*0
.34*0
.30*0
.06*0
.29*0
.12*0
.07*0
.18*0
.06*0
.28
.50
.06
.12
.18
.25
.12
.37
.18
0.0064
0.0095
0.0069
Limestone^
Dryer
Silo Loading
System
Roof9
Monitor
Mine
Portal
1500-1530 9/28c -0.06*0.19 -0.13*0.24
1129-1429 9/28c 0.25*0.20 0.18*0.24
1230-1500
0100-0400
9/25c 0.03*0.08
9/28 3.0 ±0.4
Source Average
-0.01*0.11
2.2 *0.6
1.1 *1.6
0800-1100
1100-1400
1600-1900
0100-0400
0800-1100
1600-1900
0100-0400
9/25
9/25c
9/25
9/26
9/26
9/26
9/27
76 * 4
93 * 3
64 * 2
56 * 2
58 * 2
70 * 2
78 * 2
76
93
Source Average
64 * 2
56 * 2
58 * 2
70 * 2
77 * 2
/I * 13
<0.001
<0.001
0.91
230
a) Nanocuries (10~9 curies) per cubic meter, plus or minus twice the
standard deviation, based on counting results only.
b) Radon-222 concentration in sample minus the concentration in ambient air
during the sample collection period plus or minus the standard deviation
based on counting statistics. The source average includes one standard
deviaton based on sample variability.
c) Derived from duplicate samples.
17
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TABLE 4 (continued)
d) 4992 hours per year operation.
e) 8344 hours per year operation.
f) 650 hours per year operation.
g) 1572 m /min exhaust rate at time of sampling (rate variable during year).
The only measurable concentrations of radioactive airborne particulates
(Table 3) in the mine ventilation air were Pb-210 and Po-210. Measured concen-
trations were 0.38 _+ 0.03 and 0.43 _+ 0.08 pCi/m , respectively. At the
observed flow rate of 6230 m /min these concentrations would result in
annual releases of 1.2 +_ 0.1 and 1.4 +_ 0.3 mCi of the detected radionuclides.
The Pb-210 and Po-210 concentrations would normally be considered as above the
expected ambient concentrations. In this case, however, they are very similar
to the ambient concentrations measured during the preceding 24 hours and are
not considered to be elevated.
2. Mine Working Level Measurements
Radon daughter working levels were measured at several locations in the
mine for comparison to MSHA's reported measurements and to radon concentra-
tions. Working level measurements were made in the ventilation air flow at
the 1350-foot level prior to reaching the working areas of the mine; at the
1350-foot level where air was picked up from the 1440-, 1410-, and 1380-foot
levels; at the 1110-foot level after the air had passed all working areas; and
at the exhaust portal. As would be expected, the radon daughter concentra-
tions increased with distance through the mine. The results are presented in
Table 5. Blasting on September 26 occurred at 0700 hours at the end of the
previous shift. The 0.4 and 0.24 working level measurements at the portal
were made downstream from the mine exhaust fan and may not represent the
maximum radon daughter concentration, due to some loss in the fan and
turbulent area near the fan. MSHA had measured 0.6 WL just upstream of the
fan; their measurements otherwise were similar to those reported here.
18
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3. Mill Emission Samples
Only one radon sample collected from the various emission points in the
mill was significantly above background (Table 4). Samples collected from the
secondary crusher and concentrate dryer produced concentrations which were
greater than ambient concentrations at the time of sampling, but the
associated counting error terms were such that no significance can be attached
to those higher values. The one sample significantly above ambient was a net
concentration of 2.2 ^ 0.6 nCi/m from the roof monitor of the concentrator
building. Rated exhaust fan capacities give a ventilation rate at that time
of 1572 m /min. The average annual radon-222 emission rate from the concen-
trator building, based on the two sets of samples, was 0.91 curies. The total
radon emission rate from the mill would be less than 1 Ci per year.
TABLE 5. MINE WORKING LEVEL MEASUREMENTS
Location Date Time Working Level
1350-foot level 9/26 1002 0.012
fresh air inlet
1350-foot level 9/26 0920 0.029
pickup from lower
levels
1110-foot level after 9/26 0815 0.059
all work areas
Mine Portal 9/25 1445 0.4
Mine Portal 9/29 1145 0.24
19
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The small amount of material collected on the stack and mine portal
samples, the low radioactivity content of that material, and the radioactivity
of blank samples combined to yield stack effluent concentrations that were not
significantly different from zero. In order to derive a better estimate of
the radioactivity emission rates the mass of material collected from each
source and the measured radioactivity concentration in the related process
sample were used. Table 6 shows the radioactivity emission rates inferred
from this. The concentrate dryer releases the majority of the particulate
radioactivity emitted by the mine and mill. This results from the combination
of mass emission rates; radioactivity concentration in the emitted material;
and annual operating time. Of the radionuclides measured, radium-226 produces
the greatest radiation dose per unit of radioactivity emitted. The Friedens-
ville mine and mill releases less then 1 uCi of radium-226 per year.
Radon flux rates measured from the tailings piles and background locations
are shown in Table 7. The differences in the average radon flux rates between
the new tailings pile, old tailings pile, and background, are not statistically
significant. The results, however, are consistent with expectations. Radium
measurements in the ore and tailings showed lower than average concentrations.
Average radon flux rates over the continental United States are about 35
2
pCi/m /min (Turekian, et al., 1977). The average measured background of
16+8 pCi/m /min is lower than the average, but is within the expected
range. The low radium-226 content of the tailings would be expected to result
in a low radon flux, as was found in the tailings piles. Also, the new tail-
ings pile is quite wet, which would further reduce the flux below that from the
old tailings pile (Rogers, et al.). The old tailings pile has been covered
with a layer of local soil and revegetated. The addition of local soil and
relative dryness both probably tend to increase the radon flux above that of
the new tailings pile.
VIII. POPULATION DISTRIBUTION
The Friedensville mine and mill are located in a rural area of eastern
Lehigh County. Within 2 kilometers of the mine portal residences are generally
scattered along several main roads, with the exception of the New Jersey Zinc
20
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TABLE 6. ESTIMATED ANNUAL RADIOACTIVITY EMISSIONS
Participate Radionucl ides fuCi/y?a
Mass Emission
Source Rate (kg/h) U-238 _ U-234 _ Th-230 _ Ra-226 _ Pb-210 _ Po-210 _ Th-232 _ Tn-228
Secondary 0.0733 0.066 * 0.029 0.066 * 0.032 0.054 * 0.014 0.040 * 0.004 0.13 * 0.12 0.084 * 0.032 0.029 * 0.011 0.018 * 0.007
Crusher
Tertiary 0,285 0.43 * 0.19 0.43 * 0.21 0.36 ± 0.10 0.26 ± 0.02 1.1 * O.S 0.5S ± 0.21 0.19 ± 0.07 0.12 ± 0.05
Crusher
Concentrate 0.908 1.2 ± 0.2 1.2 ± 0.2 0.98 * 0.30 0.45 ± 0.08 -0.98 * 7.3 1.4 ± 0.7 0.30 * 0.15 0.30 * 0.15
Dryer
Mine Portal 0.075 0.12 ± 0.05 0.12 * 0.06 0.10 * 0.03 0.07 * 0.01 0.32 * 0.21 0.15 * 0.06 0.05 ± 0.02 0.03 * 0.01
a) Microcuries (10~*> curies) per year, calculated from mass emission rate and process sample radioactivity concentrations.
-------
TABLE 7. RADON-222 FLUX FROM SOIL AND TAILINGS
Canister
No.
15
31
33
35
36
38
42
45
48
53
55
59
60
65
70
73
75
76
77
78
82
86
87
89
92
Location
New Tailings Pile
New Tailings Pile
New Tailings Pile
New Tailings Pile
New Tailings Pile
New Tailings Pile
New Tailings Pile
New Tailings Pile
New Tailings Pile
Old Tailings Pile
Old Tailings Pile
Old Tailings Pile
Old Tailings Pile
Old Tailings Pile
Old Tailings Pile
Old Tailings Pile
Old Tailings Pile
Both
Background
Background
Background
Background
Background
Background
Background
Background
Rn-222 Emanation Rate
(pCi/m2-min)
4.4
11
9.7
6.6
1.9
4.7
2.2
5.3
6.3
6.0
8.6
6.7
11
6.9
7.3
6.3
9.1
Piles Average
23
18
21
11
7.4
17
27
4.7
Average/Location
(pCi/m2-min)
-*
5.8 ± 3.1a
«*
7.7 ± 1.7a
6.7 ± 1.8b
a
16 ± 7.8a
a) Average ± the standard deviation of the mean
b) Average +_ the standard error of the mean
22
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Company's employee housing at Friedensville. Figure 4 shows the relationship
of the mine, mill, and tailings piles to the surrounding population. The
nearest residence to the mine portal is about 200 meters east. Beyond that,
residences are located along the Old Bethlehem Pike about 300 meters east of
the portal. Several residences are located about 200 meters south of the mill
and the company-owned housing area is about 500 meters east of the mill.
IX. DISCUSSION OF RESULTS
Of the radionuclides measured, radium-226 produces the greatest radiation
dose per unit of radioactivity released. The Friedensville mine and mill
releases less than 1 ?Ci of radium-226 per year.
The difference in radon flux for the tailings piles and background areas
results in a reduction in radon emanation to the atmosphere from soil of about
1 Ci/y. This would about offset the amount emitted from the mill.
The mine releases 230 Ci/y of radon-222. The high radon concentration in
the mine atmosphere, confirmed by working level measurements, is not explained
by the low radioactivity of the ore itself. The low radioactivity of the ore
and the relatively solid mine interior surfaces should result in a very low
radon flux from the surfaces. The most likely explanation for the presence of
the majority of the radon detected lies in the water influx. Water literally
rains from the mine roof and pours from the walls at the rate of
3
110m /min. It is probable that the water, under high pressure in the rock,
carries considerable dissolved radon which is released into the mine
atmosphere. The water is continually aerated as it enters and is pumped
through the mine. A water sample collected from the mine discharge still
contained 50 pCi/1, which was probably only a few percent of the concentration
in water initially entering the mine (Misaqi). It is quite conceivable,
therefore, that the water had had enough radon originally dissolved in it to
account for most of the estimated annual release rate of 230 Ci.
23
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MINE
A......*""*-' '' PORTAL
Figure 4. Map of Friedensville Mine and Mill with Surrounding Area.
24
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REFERENCES
Code of Federal Regulations, Title 40, Chapter 1, Part 50, Appendix B
Code of Federal Regulations, Title 40, Chapter 1, Part 60, Appendix A
Engineering-Science, Emission test report. Collection of airborne radon and
radioactive particulates at New Jersey Zinc Company's Friedensville Mine,
Friedensville, Pennsylvania. Me Lean, Virginia, December 1978.
Goodwin, Aurel. Mine Safety and Health Administration. Personal communica-
tion, 1978.
Misaqi, Fazlollah L. Monitoring Radon-222 Content of Mine Waters,
Informational Report 1026. U.S. Department of Interior, Mining Enforcement
and Safety Administration, Denver Technical Support Center, Denver, Colorado
National Council on Radiation Protection and Measurements. Natural Background
Radiation in the United States, NCRP Report No. 45, 1975. Washington, D.C.
Rogers, V.C., et al. Characterization of uranium tailings cover materials for
radon flux reduction. U.S. NRC Report NUREG/CR-1081, March 1980.
Slade, David H., editor. Meteorology and Atomic Energy 1968. U.S. Atomic
Energy Commission, Oak Ridge, Tennessee. July 1968
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.
25
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-520/6-82-020
2.
3. RECIPIENT'S ACCESSION NO.
4. TITLE AND SUBTITLE
Emissions of Naturally Occurring Radioactivity:
Underground Zinc Mine and Mill
5. REPORT n»TP,
November 1982
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Vernon E. Andrews
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
10. PROGRAM ELEMENT NO.
U.S. Environmental Protection Agency
Office of Radiation Programs-Las Vegas Facility
P.O. Box 18416
Las Vegas, Nevada 89114
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Same as above
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
15. SUPPLEMENTARY NOTES
This is the second in a series of reports covering work performed in response to the
1977 Clean Air Act Amendments.
18. ABSTRACT
Atmospheric emissions of naturally occurring radioactivity were measured
from an underground zinc mine and mill. The only significant radioactive
emission from the mine or mill was radon-222. An estimated 230 curies of
radon-222 is released annually from the mine. The primary source of radon is
believed to be the high influx of water which is pumped from the mine at the
rate of 110 cubic meters per minute.
17.
KEY WORDS AND DOCUMENT ANALYSIS
a.
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS
c. COSATI Field/Group
Natural radioactivity
Airborne wastes
Exhaust gases
Underground mining
Beneficiation
Tailings
Technologically
enhanced
radioactivity
1808
1302
2102
1308
18. DISTRIBUTION STATEMENT
Release to public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
25
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (R»». 4-77) Previous EDITION IS OBSOLETE
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