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.