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Transcript of Environmental Attributes of Mining and Processing of ...€¦ · Environmental Attributes of Mining...
Environmental Attributes of Mining and Processing
of Uranium Ore in Singhbhum, Jharkhand, India
V.N. JHA HEALTH PHYSICS UNIT, JADUGUDA
HEALTH PHYSICS Division Bhabha Atomic Research Centre
Trombay, Mumbai – 400 085 Email : [email protected]
Tel. : +91-22-2559 5415 +91-657-2731231 Fax : +91-657-2730 322
12/11/2015
Mines 1. Jaduguda
2. Narwapahar
3. Bhatin
4. Turamdih
5. Banduhurang (O/C)
6. Bagjata
7. Mohuldih (development)
Ore Processing Plants 1. Jaduguda Mill
2. Turamdih Mill
Tailings Ponds 1. Three Numbers of Tailings Pond at Jaduguda
2. OneTailings pond at Turamdih
Ore Mining
Crushing and Grinding
Leaching and Filtration
Ion Exchange
Hydro cyclone
Precipitation and Drying
Yellow cake (MDU)
Transported to NFC (Hyderabad, A.P)
Coarse Fine
Mine back
filling
TP
ETP
Local
Discharge
Hydrometallurgical process
BarrenLiquor
BarrenCake
FLOW SHEET FOR URANIUM ORE PROCESSING
Radiological Concern of Environment Around Uranium Mines
Release of gaseous 222Rn and progeny
Long-lived alpha active dust
Mine water containing dissolved radionuclides
Overburden and waste rock
Radiological Concern of Environment Around Uranium Mill
Tailings disposal
Effluent discharges
Gaseous releases
Radioactive Features of Mill Tailings
The milling of uranium ore removes ~ 90% uranium Tailings contain all the decay products of U-238 and U-235 series The radioactivity of uranium tailings controlled by three principal radionuclides - Th-234 (half-life (t½ - 24.1 days) Th-230 (t½ - 80,000 years) Ra-226 (t1/2 - 1600 years) and Residual uranium (U-238, t½ - 4.51 billion years; U-235 t½ - 710 million years)
ENVIRONMENTAL CONCERN OF URANIUM MILL
TAILINGS
1. They retain much of the radioactivity of the concerned ore
2. Their radioactivity is long lived 3. Their granular to slime consistency makes them
susceptible to leaching, erosion or collapse under various conditions
4. A large surface area to the natural elements and thus increases the risk of release of radiation flux, radioactive and geochemically toxic dusts
5. Interaction with surface water/ ground water systems
At JADUGUDA - three valley-dam type of tailings ponds One operational Two Saturated to Filled capacity
At Turamdih – One tailings ponds operating
In all the four tailings pond neutral solid is retained and liquid effluent is allowed to drained for further treatment prior to disposal
11
Monitoring - Why?
• Monitoring provides the basis to demonstrate compliance with the regulatory requirements.
• Monitoring and surveillance are vital tools in confirming that
operations and facilities are performing as expected.
Facilities and releases
Pathways & transfer in environment
Regulatory requirements
Detection Basics
Monitoring strategy
Inputs of monitoring
Monitoring objectives
To gather data related to sources of human
exposure in the area
Evaluation of radiological status of the environment
Assessment of radiation exposure to members of the
public
Ensure adequacy of control measures / Evaluation
of regulatory compliance
Develop suitable protocols & techniques to carry out
the Environmental Surveillance Programme
Occupational
Monitoring
Environmental
Environmental Routine Monitoring Matrix Parameters
Effluent U, 226Ra, Conventional
Surface water -do-
Ground water -do-
Monitoring wells (TP) -do-
Soil U, 226Ra, 230Th, 210PO
Sediment -do-
Vegetables -do-
Seepage & overflow -do-
External gamma radiation survey
Measurement of 222Rn & its progeny concentration in
atmosphere
DOSE RATES ON THE TAILINGS SURFACE
•The gamma radiation dose rates 1m directly
above the tailings pile range from about 0.75–3.3 uGy h-1, averaging around 1 uGy h-1
• This reduces to about 0.2 - 0.5 uGy h-1 on the
embankment Note: Normal background level 0.10-0.20 µGy.h-1
(10-15 µR.h-1)
Sample collection & preparation:
Effluent, Surface water and ground water
i. Grab samples are collected from inlet and outlet of
ETP, Surface water from upstream and
downstream with respect to discharge (Juria/Gara
and Suvernrekha river)
ii. Ground water samples are collected from wells
and tube wells from areas near tailings pond and
away.
iii. Samples are filtered immediately after collection
and preserved in conc.HNO3 (1 ml/l)
Analytical procedure U (nat)- Solvent extraction in alamine benzene solvent, fusion of organic layer with Na2CO3
: NaF (85:15), Fluorimetry, comparison with standard. Uranium evaluated from sample reading, blank reading and sampling parameters
226Ra- Concentrated water, effluent or digested aliquot loaded in
emanometric set up. In built radon removed, left for fresh build up of radon. Radon collected in evacuated Scintillation cell, left for 200 min to ensure equilibrium, alpha counted. 226Ra determined from build up, delay, efficiency and sampling parameters
492
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Average Natural Background in Different States of India
Atmospheric radon levels are periodically
measured adjoining the mining, ore processing
and tailings management facilities of Singhbhum.
Distance away from the facilities is also
periodically monitored for atmospheric radon. The
average radon concentrations around Bagjata
mining region was 28 ± 11 Bq m-3, around
Jaduguda 35 ± 7, Narwapahar are 25 ± 9 and
Turamdih around 25 ± 5 Bqm-3, respectively.
•The effectiveness of the effluent treatment plant in
controlling the release of radioactive materials to the
aquatic environment is evaluated by measurement of
U(nat.) and 226Ra in the inlet and outlet effluents.
Effluent and Surface water
Concentration of U(nat) in treated effluent at Jaduguda
was ranging from 1.2 to 7.7 mg l-1 with median
concentration of 2.7 mg l-1 and 226Ra concentration was
ranging from 3.5 to 176 mBq l-1 with median concentration
of 4 mBq l-1.
The U(nat.) and 226Ra concentrations observed in the
surface waters of nearby river of Jaduguda was found to
vary from 2.2 – 55 mg l-1 and 3.6–45 mBq l-1 with median
concentration of 7.8 mg l-1 and 10. 5 mBq l-1 respectively.
The U(nat.) and 226Ra concentrations observed in the
surface waters of nearby stream of Turamdih was found
to vary from 2.2 – 16 mg l-1 and 4 –20 mBq l-1 with median
concentration of 9.1 mg l-1 and 7 mBq l-1 respectively.
Natural Radioactivity Levels in Soil
Distance from the
facility (km)
N
U(nat)
mg kg-1
226Ra
Bq kg-1
Jaduguda
0.5 5 2.8 25
0.5-1.6 4 2.6 35
1.6-5 4 2.1 44
5-10.0 4 3.3 53
>10 3 1.9 42
Turamdih
< 1.6 20 1.5 23
1.6 – 5 24 1.7 31
5 -10 16 1.8 36
Narwaphar
< 0.5 4 1.1 23.4
0.5-1.6 4 1.3 35.5
1.6-5 8 1.4 39
5-10 10 1.6 41
Bagjata
0.5 5 2 52
0.5 – 1.6 4 3.6 89
1.6-5 4 3.1 47
5-10 4 2.9 60
> 10 3 2.2 57
Median concentration of radionuclide in monitoring well around tailings pond
Monitoring Well No.
(Jaduguda)
U(nat)
mg l-1
226Ra
mBq l-1
1 1.6 60
2 1.9 33
3 2.7 29
4 1.9 21
5 2.2 10
6 3.2 10
7 1.7 19.5
DWC Limit 60 300
Monitoring Well
No. (Turamdih)
U(nat)
mg l-1
226Ra
mBq l-1
1 1.1 9
2 0.9 11
3 3.2 10
4 1.4 18
5 0.8 11
6 2.1 26
7 4.3 17
8 1.1 25 DWC Limit
60 300
Median concentration of radionuclide in monitoring well around tailings pond
Distance from TP
(kms)
N
25th 50th 75th
0-0.5 101 0.5 0.91 2.1
0.5 – 1.6 167 0.5 1.4 3.6
1.6 – 5 97 0.5 0.8 2.7
5 -10 129 0.5 0.6 2.0
Percentile distribution of uranium (mg l-1) in ground water at
different distances from tailings pond
Distance from TP
(kms)
N
25th 50th 75th
0-0.5 101 3.5 8.9 77 0.5 – 1.6 167 3.5 6.5 15.3 1.6 – 5 97 3.5 8.2 21.8 5 -10 129 3.5 6.8 18.6
Percentile distribution of 226Ra (mBq l-1) in ground water at different
distances from tailings pond
Distance from the
facility
N
U(nat)
mg kg-1
226Ra
Bq kg-1
Jaduguda
0.5 5 2.8 25
0.5-1.6 4 2.6 35
1.6-5 4 2.1 44
5-10.0 4 3.3 53
>10 3 1.9 42
Turamdih
< 1.6 20 1.5 23
1.6 - 5 24 1.7 31
5 -10 16 1.8 36
Narwaphar
< 0.5 4 1.1 23.4
0.5-1.6 4 1.3 35.5
Activity Concentration of Radionuclide in soil around uranium
mining and ore processing facility (2013-14)
Narwapahar
1.6-5 8 1.4 39
5-10 10 1.6 41
Bagjata
0.5 5 2 52
0.5 – 1.6 4 3.6 89
1.6-5 4 3.1 47
5-10 4 2.9 60
> 10 3 2.2 57
Activity Concentration of Radionuclide in soil around uranium
mining and ore processing facility (2013-14)
0.00
0.50
1.00
1.50
2.00
2.50
Inh
ala
tio
n d
ose (
mS
v/y
) Annual dose due to radon (outdoor) to the public (mSv/y) around uranium Tailings Pond (TP), Jaduguda
0 km
20 km 5 km
50 m 500 m
1 km 1.5 km
2 km 3 km 10 km
Particulate dust (LLα)
Low grade ore and tailings have negligible contribution
Long-lived radioactivity from ore and tailings dust is
significant only for ores grades above 1 % U3O8
Control measures of water spray and dust extraction at
the mine and mill sites and proper soil and vegetation
cover over the waste rocks and tailings surfaces will
reduce the generation and dispersal of dust
RADIATION EXPOSURE PATHWAYS RADIATION
SOURCE
AIR WATER
SOIL SAND &
SEDIMENTS
ANIMALS PLANTS
MILK MEAT
AQUATIC
ANIMALS
AQUATIC
PLANTS
FISHING
GEAR
HUMAN
Public Dose Evaluation
Integrated gamma (Environmental TLD),
Gamma survey, occupancy factor
Inhalation dose 222Rn progeny concentration
(Indoor and Outdoor) occupancy and
integrated passive radon cup type dosimeter
Internal exposure
Radionuclides in dietary components
Consumption data (National average or
dietary survey)
Total dose = External gamma + Inhalation +
Ingestion
Uranium mining activities in the Singhbhum region of Jharkhand state, India have been carried out for the last five decades.
Study reveal that the radioactivity and radiation dose to members of the public residing around the uranium mining complex is comparable to other regions of the world.
Baseline studies and comparison: Baseline studies
incorporating radiological, non-radiological, health, demographic,
hydrogeological, biodiversity concerns. A closer look of the
radiological component of baseline studies at Bagjata and
Turamdih reveal the fact that almost after a decade operation has
not altered the exposure pattern of the population residing around
these areas.
Non-radiological attributes of the environment: Heavy
metal content in diverse matrices, suspended and
respirable particulate matter in the air, SOx, NOx in air,
anions in drinking water, basic water quality parameters in
treated effluent, surface water and ground water.
RULES APPLICABLE TO URANIUM MINING AND MILLING
ATOMIC ENERGY ACT, 1962.
• RADIATION PROTECTION RULES, 1971.
• NOTIFICATION DATED 15.03.1995 RELATING TO
PRESCRIBED SUBSTANCES
3. ATOMIC ENERGY (WORKING OF THE MINES, MINERALS
AND HAHDLING OF THE PRESCRIBED SUBSTANCES),
RULES 1984.
4. ATOMIC ENERGY (SAFE DISPOSAL OF RADIOACTIVE
WASTES) RULES, 1987.
5. Public and Community participation
THESE ARE IN ADDITION TO RELEVANT RULES AND
REGULATIONS FRAMED UNDER MINES AS WELL AS
ENVIRONMENTAL POLLUTION CONTROL ACTS.
Conclusion The state of art technology adopted by uranium mining and
processing industry of India and regular surveillance/
monitoring ensure environmental supportive operations of
the facilities. Regular discharges of tailings nearly for five
decades around Jaduguda and a decade around Turamdih
did not alter the pre existing status of the radiological
environment. The surveillance & monitoring capabilities of
the expert and community participation in achieving the
environmental protection targets is anticipated to ensure
sustainability of the industry for decades.