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RADIOECOLOGICAL IMPACTS OF DIRECT APPLICATION OF PHOSPHATE ROCK (DAPR) Prof. ASHRAF KHATER PHYSICS...
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Transcript of RADIOECOLOGICAL IMPACTS OF DIRECT APPLICATION OF PHOSPHATE ROCK (DAPR) Prof. ASHRAF KHATER PHYSICS...
RADIOECOLOGICAL IMPACTS OF DIRECT APPLICATION OF
PHOSPHATE ROCK (DAPR)
Prof. ASHRAF KHATERPHYSICS DEPT.- KING SAUD UNI.
SAUDI ARABIA
Conclusions
DAPR and U in phosphate industries are;
Radioecolgical aspects of PI
Radioecolgical aspects PI
Natural Radionuclides(238U series, 232Th series and 40K)
NORM(238U series, 232Th series and 40K)
Occupational Exposure
Public Exposure
Products, by-
products,
Tailing, wastes,..
waste water
dustEnvironmental Impacts
Source
Processing
Application
Disposal
Original conc.
Enhanced Conc.
Increase exposure
Environ. Impact
Avoid at source
Change process
precaution or avoid
Condition or remediation
IAEA- TRS-419
ENVIRONMENAL IMPACTS
Behaviour of radionuclides in terrestrial ecosystems
External Exposure
From theplume
Fromground
Internal Exposure
Inhalation
(contaminatedFoodstuffs)
Exposure pathways
DAPRPhosphorus (P) is an essential for plant growth and increase
production yield.
Phosphate industries are one of the most consistent sources for
hazardous materials (e.g. stable and radioactive trace elements)
accumulation in the environment.
Agricultural direct application of phosphate rock (DAPR) to tropical
acid soils is an alternative well known practice to chemical P
fertilizers (FP).
Phosphate ore
Phosphate rock is the starting raw material for all phosphate products.
Phosphate deposits contain calcium and phosphorus, essentially as
tri-calcium phosphate, Ca3(PO4)2;
(i) Sedimentary marine deposits;
(ii) Igneous (magmatic) deposits;
(iii) Metamorphic deposits;
(iv) Biogenic deposits, mainly accumulations of bird and bat
guano;
(v) Deposits caused by weathering.
Phosphate oreTotal global phosphate deposits are estimated to be 67 billion t. Most
of these deposits are of sedimentary origin. Annual worldwide
production is 210 Mt (2012);
– 71% of all phosphate rock produced is processed into phosphoric
acid, The annual production of P2O5 in the form of phosphoric acid
is more than 30 million tone and about 120 phosphogypsum.
– 24% is processed directly into fertilizer,
– 5% is converted directly into various other products,
– Elemental phosphorus by reduction in an electric arc furnace in a
process known as the ‘thermal process’, relatively small amount
Most of the phosphoric acid ( 75- 90%) , (55–60% of
total rock ) is convert to fertilizer. The fertilizer products
so derived from phosphoric acid
The remaining ,10–25% , is processed equally into
animal feed supplements and into a variety of other
products.
The major source of phosphorus is PR (a finite and non-renewable
resource). Phosphate rock is the primary raw material for producing
soluble P fertilizers.
It can be applied directly and can solubilize in the soil, making the P
available to crops depending on the type of rock, soil properties,
climatic conditions, crops/cropping systems, and nutrient
management practices.
the suitability of DAPR:
– Type/source of apatite and solubility characteristics
– Soil properties
– Crop species
– Management practices
– Socio-economic conditions
U and some trace element in PR
P2O5% Pb Cd As U Ore
2729
2631
2.92.6
3830
2628
Abu-Tartor-I
27-29 4 9 10 70 Abu-Tartor-II
- 18 14 14 77 Hamrawain
- 9 9 13 70
- 5 5 10 44
- 6 14 9 61
- 4.4 4.6 8.4 46
- 17 17 7.5 40
- 8 11 10 56 Ave.
34 2.6 5.9 30 42 Traif (SA)
Evaluation the radioecological impacts of DAPR!!!!
AAL (kg/h)
+EC (PL) TAV*(mg/kg)
MAC*(mg/kg)
- - - U
- 8 10-65 15-20 As
0.166 1.5 2-10 1-5 Cd
33 100 50-300 20-300 Pb
* Kabata- Pendios, 2010 + EC, 1986
Pb Cd U
33 0.166 0.015 * AAL (kg/ha)
82488 461 5.5 + 2 Time (t), y +
(3-10)
* Based on Canadian limit of 23 mg/kg for agricultural soil+ calculated based on application rate of 600 kg PR/ha.y
Phosphate beneficiation
BEEFI
C I
ATON
Phosphate rock 4E6 ton & 24%
Wet ore 2.2E6 ton &31%
Crushing
Sorting
Wet Screening
Magnetic Separation
Flotation
Hand pick-up (clay and dol. Rocks)
13E4 & 3 %
≥ 2 mm rejects 21E4 & 5%
Mag. Sep. reject 28E4 & 7%
Slime 1E6 & 27
Rej
ects
Wet process
sulphuric acid phosphorus extraction process
U and some trace element (ppm) fractionation in beneficiation processes
% P2O5 % Pb Cd As U
100 27 26 2.9 38 26 ROM
55 29 31 2.6 30 28 Conc
5 17 28 2 24 18 + 2 mm
7 29 30 2.1 36 25 Mag
25 19 27 1.7 28 18 Slim
U-238 Ra-226 Pb-2100
50
100
150
200
250
300
350
400
Act
ivity
con
cent
ratio
n, B
q kg
-1 Ore Conc. 2 mm Mag Slime Dol Clay
5 10 15 20 25 30 35
50
100
150
200
250
300
350
238 U
, B
q k
g-1
P2O
5 %
Equation y = a + b*xAdj. R-Squa 0.71506 R- valu 0.87
Value Standard ErrIntercept 8.9840 7.72397Slope 11.4760 0.38347
Linear Fit
0 50 100 150 200 250 300 350 400 4500
50
150
200
250
300
350
400
450
238U
- G &
T (B
q kg
-1)
238U-A (Bgkg-1)
Equation y = a + b*x
Adj. R-Square 0.9458 0.94288
Value Standard Error
U-238T Intercept 36.8611 6.51964
U-238T Slope 0.7438 0.03245
U-238G Intercept 13.14416 4.30737
U-238G Slope 0.84687 0.02995
238U-G
238U-T
238
U-G 238
U-T linear Fit
0 50 100 150 200 250 300 350 4000
50
100
150
200
250
300
350
400
X=Y
oreMagConc.
Slime
2mm
Dol.Act
ivity
con
cent
ratio
n, B
q kg
-1
238U, Bqkg-1
226Ra 210Pb
226Ra Linear Fit 210Pb Linear Fit
Clay
Equation y = a + b*xAdj. R-Square 0.97607 R 0.98
Value Standard ErrorRa-226 Intercept 7.55454 1.56394Ra-226 Slope 1.04294 0.01369
Equation y = a + b*xAdj. R-Square 0.9719 R 0.98
Value Standard ErrorPb-210 Intercept 10.87136 4.00538Pb-210 Slope 0.72085 0.03218
Measurement of Pb-210 using different techniques
Ore Conc. 2 mm Mag slime Dol Clay0
100
200
300
400
500
Bq/
kg
Gamma Alpha Beta
Ore Conc. 2 mm Mag. slime Dol. Clay0
10
20
30
40
50
60
70
80
90
200
250
300
350
400
Act
ivity
conce
ntratio
n, B
q k
g-1
238U 232Th 40K
IFA, 2013
The use of DAPR has fallen because of environmental restrictions in the unloading of
finely ground PR and the increasing availability of water soluble chemical PF.
• It would be very practical to use PR for direct application as source of P after
considering the PR characterization, soil properties and other parameter.
• The main advantages of DAPR and /or phosphate beneficiation by products are;
• The cost,
• Reducing the amount of PI wastes such as phosphogypsum produced ,
• Recycling the by products due to beneficiation processes.
• It seems that the evaluation processes of the ecological impacts of phosphate
industries are fuzzy confused.
URANIUM IN PHOSPHATE FERTILIZERS: CONCENTRATION AND ENVIRONMENTAL IMPACTS
Prof. ASHRAF KHATERPHYSICS DEPT.- KING SAUD UNI.
SAUDI ARABIA
• Phosphate industries (PI) are one of the most consistent sources for some
hazardous trace as well as radioactive elements that could be accumulated
in the environment especially in cropland soil.
• Since the 1950s, the application of plant nutrients, including phosphate fertilizers, has
increased substantially.
• The long-continued application of phosphate fertilizers can redistribute
and elevate uranium and toxic heavy metals, such as As, Cd and Pb in soil
profiles and consequently their transfer to the food chain, mainly in acid
soils. It can also raise these elements concentration in irrigation
runoff/drainage waters (da Conceicao and Bonotto 2006).
Uranium in world P-resources can feed the nuclear energy cycle for 350 years
(World U resources actually: approx. for 50 more years)
cleaner fertilizers
cleaner soils
cleaner waters
cleaner atmosphere
By: Prof. Ewald Schnug
Phosphate fertilizers
Phosphate rock product streams
Wet process
sulphuric acid phosphorus extraction process
Phosphogypsum
Th-232 Po-210 Pb-210 U-238 Ra-226
11 437-1765 577-1853 41-366 507-1358 USA- Fl
10 900 1300 500 15-1700 Europe
205-284 76-132 64-73 45-48 South Africa
4-7 150-360 320-440 10-24 280-350 Australia
IN PHOSPHOGYPSUM (Bq/kg)
It has been estimated that, by 2006, a total of
2.6–3.7 billion t of phosphogypsum had been accumulated in stacks worldwide
A phosphogypsum stack in central Florida, USA
It has been estimated that, by 2006, a total of 2.6–3.7 billion t of phosphogypsum had been accumulated in stacks worldwide,
Sampling and sample preparation
Analytical techniques
Uranium concentrations in PF
WS GI GL
0.26( 0.06. - 57) 39( 14-31) 174( 38-329) U (ppm)
(20-52) 17( 17-20) 38 ( 23-52) P)%(
05101520253035400
50
100
150
200
250
300
350
U (ppm) in Local granule PF
U concentrations in locally
produced fertilizers are higher
than that of imported
fertilizers, which depend on
their levels in phosphate rocks
and chemical treatments
(sulfuric or nitric acids
chemical attack).
Radium-226/Uranium-238
activity ratios were ranged from
0.002 to 0.003 and from 0.2 to
0.8 in locally produced and
imported samples, respectively.
It is related to the chemical
processing of phosphate rocks,
either sulfuric or nitric acid
chemical attack.
0 50 100 150 200 250 3000
500
1000
1500
2000
2500 Exponential Decay 1st order
Model: Exponential Decay 1st.degree Equation: y = A1*exp(-x/t1) + y0 Weighting:y Instrumental
R2 = 0.81765 y0 212.54742 ±0.19073A1 1832.21812 ±3.5319t1 7.04207 ±0.03107
U-2
38
Ra-226
0
50
100
150
200
Ura
niu
m, p
pm
Country
Minimum Maximum
0 500 1000 1500 2000 2500
15
20
25
30
35
40
45
50P
2O
5 %
U-238, Bq/kg
Linear Fit95 % Confidence Limit
R2 = 0.9
Y = 12.76 + 0.016 X
• There is no limit or a regulation for U concentration in PF !!!!!!
• The rate of PF application depend on their P content. Most literature, if not
all, express the uranium concentration per phosphate mass which are
mainless. U concentration should be expressed per unit mass of P.
• The relation ship between U concentration and PF physical forms needs
more research.
P fertilizersThere is no MAC for natural radionuclides in FP.
– The federal German authority for environmental protection is going to recommend 20-50 mg U/ kg P2O5.
– the recommended Canadian Soil Quality Guidelines for the protection of environmental and human health are
23 mg/kg for agricultural land & residential/parkland land use,
33 mg/kg for commercial land use, and
300 mg/kg for industrial land use (due to off-site migration check) .
# Long-term impacts of P fertilizationThe mobilization and accumulation behavior of U in soil plays a key role in risk assessment studies
Twenty eight soil samples were collected from 14 location in 25 year old farm,
where one cultivated (in) and another uncultivated soil (out) from each location.
Fourteen water sample were collected from 14 underground water wells, as
shown (map)
All soil samples were dried, crushed, homogenized and sieved through 2 mm
sieve
All soil samples were leached using Aqua Rigia and completely dissolved using
mineral acid (HF, HNO3, HCl)
Uranium in soil and water samples were measured using Perkin Elmmer ICP-MS
model ELAN-9000 at ALS Chemex – Canada.
Soil physical and chemical properties (pH, EC, organic matter %, CaCo3%,
soluble anions and soluble cations) and soil texture (clay%, silt% and sand %)
were determined using standard method (Omran 1987)
Uranium activity concentration in Bq/kg
Average uranium concentration, mg/kg (Bq/kg) in different countries soil
Mean Range Country
1.9( 24) 1.7-2.2 S.A
1.22( 15) 0.42-11 Canada
3.7( 46)2.5( 31)
0.3-11 <0.01 – 45
U.S.AEurope
Kabata- Pendias, 2001 & Salminen 2005
6 8 10 12 14 16 18 206
8
10
12
14
16
18
U
-238
out
U-238 In
8 10 12 14 16 18 20
0.8
1.0
1.2
1.4
1.6
U-2
38
, I/O
ra
tio
U-238 In, Bq/kg
Leachable U in Soil
8 10 12 14 16 18 20
0.8
1.0
1.2
1.4
1.6
U-2
38
ra
tio I/
O
U-238 In
R2=0.42
6 8 10 12 14 16 18 2020
22
24
26
28
To
tal U
-23
8, B
q/k
g
Leachable U-238, Bq/kg
In Out
0 2 4 6 8 16 180
2
4
10
12
Ora
nic
mat
ter-
out
%
Organic matter-In %
2 4 6 8 16 18
0
1
2
3
4
789
Linear Fitting 95 % confidence limit
Org
an
ic m
atte
r ra
tio (
I/O
)
Organic matter-in %
R2= 0.9, P=0.0001
Interaction of radionuclides with OM leads to formation of mineral-organic complexes and chelates, which is more important than metals hydroxo complex.
OM is extremely heterogeneous. There are a large number of possible reaction and interaction of radionuclides with OM.
The stability of these complexes depends on the pH of the soil, the cation concentration in the soil, the functional gp and the degree of saturation of the potential sorption site
0 2 4 6 8 10 16 186
8
10
12
14
16
18
20
R-Square(COD) Adj. R-Square Root-MSE(SD) N---------------------------------------------------------------------------0.42855 0.18366 0.13831 1.71496 20
R R-Square(COD) Adj. R-Square Root-MSE(SD) N---------------------------------------------------------------------------0.0941 0.00885 -0.03244 2.73314 26
U
-23
8, B
q/k
g
Organic matter %
Sandy clay loam Sandy loam loamy sand0.00
2.00
4.00
6.00
8.00
10.00
12.00
Leachable U
Bq/kg
Uranium in water
Going on projects
# Industrial radioecology of Al-Jalamid phosphate mining, Saudi Arabia (NPST):
• Characterize the radiological and elemental features of phosphate mining and beneficiation materials,
• Establishment an environmental baseline assessments (EBAs),
• Evaluation of the radio-ecological impacts of phosphate mining processes,
• Evaluation and management of radiation exposure due to phosphate mining processes,
• Mining wastes and by-products characterization, management and recycling
# Radioecological impacts and risk assessment of phosphate fertilizers - Saudi Arabia (NPST) :
• Radiological and chemical characterization of TENORM
and selected heavy metals in various phosphate fertilizers
• Radioecological impacts of PFs industry.
• Radioecological impacts of long term soil fertilization .
• Risk assessment for TENORM and selected heavy metals
in PFs life cycle
• Relationship between phosphate fertilizers quality
and their physical forms.
• Application of biopolymers for heavy metals and
natural radionuclides removal.
• Removal of heavy for heavy metals and natural
radionuclides using meso-porous nano-materials.
Conclusions
Radioecolgical aspects of PI
Radioecolgical aspects PI
Time
Wastes
Achieve safe disposal and
recycle
Best Practice
Risks to Worker or Public &
environment
Thank you for your attention!
Thank you for your attention
ConclusionsSome chemical industries produce a huge amount of wastes…..
NORM is extremely high in some wastes
Their radio-ecological impacts should be investigate deeply to
ensure the environ-mental and health safety.
Toxic heavy element impacts should be considered as associated
risk with NORM,
Wastes could be considered as a mixed hazardous materials
Environmental impacts should be more studied
RP regulations for NORM in chemical industries (except uranium
and oil/gas) are not really exist.