1. Presented by:
Pr.fakhi Said Directory of Radiochemistry research group
Uranium in Moroccan sedimentary rocks: Metrology and
Geochemistry
try
S.FAKHI Said, E.Fait, R.Outayad, I. Voique, C. Galindo. A. Nourreddine, E.
Khouya, H. Elhadi, M.Aadjour, H. Hannach, M.Benmansour, A.Abderahim.
M. Mouflih
Projects: PICS 52, PICSS 802, AECID A/026017/09 and the UMR: CNESTEN and
Projects: PICS 52, PICSS 802, AECID A/026017/09 and the UMR: CNESTEN and
UHIIMC, Projet of marocain academie (oïl shales valorisation)
UHIIMC, Projet of marocain academie (oïl shales valorisation)
2. plan
Interfaces solid/ water anlysis
- Context:
- Main objectives
- Description
- Present work: Study of Solid compartment
- Area, samples and anlysis
- Results
- Conclusion
3. Global Context
- Migration of stable and radioactive metals at
the interface between Solid/ solution.
- Behavior of heavy and radioactive metals in
the environment.
- Process which control the behavior of metals
in natural environments (clay, phosphates,
Black shale,…)
3
4. Aims
•Process influencing the distribution and transfer of
metals.
•Natural and anthropic Materials for the sorption and
trapping these elements!: waste mangement applications
•Methods and proceedures of separation: application to
the separation of minor actinides and the recovery of U
(case of phosphates, oil shales and other matrix).
4
5. Description
•Scientific context:
- Processes of retention: exchange of ions on clays, the
substitution of ions in phosphates, formation of
complexes/precipitates of surface on oxides, clays and
phosphates and formation of Coprecipitates.
- studies of the questions which remain posed as for the
species formed on the mineral surface in the natural
environments i.e. in the presence of many inorganic
(phosphate, carbonate) and organics (humâtes) ligands.
-Second step: applications: séparation, material élaboration and metal recovery
-First step: compartment solid study, surronding water alaysis and interface
solid/water analysis.
5
6. Present work:
Study of Solid compartment
Optimization of the isotopes analysis methods: U, Th and of Ra and
their descendants: Gamma and alpha spectrometry and ICP-MS.
Characterization of the phases which concentrate the isotopes of U,
Th and Ra…
Applications of the methods for study of Sedimentary deposits
(Layers)
Separation of the particle size of sediment rocks as a solid horizon
study of distribution of the natural radionucléides in the different
phases and grains which constitute solid phase (case of phosphates
sediments).
Processes of extraction of U and other heavy metals starting from
phosphates , fossil, Black oil shales, clays, and calcerous …
6
7. Area, samples and anlysis
I. Phosphates from Oulad Abdoun Basin :
1. Samples : from different layers and interlayer drilling of different areas:
2. Principal aims:
- - geochemistry and distribution of natural radionuclides depending on the
depth and the drilling facies.
- - sequential extraction: contribution of the different phases in the trapping
radionuclides: (intrinsic distribution in appatite, limestone, and fossils,
- - contribution of 3 main particle size of phosphate ores in total radioactivity.
II. The Mesozoic basins essaouira-Abda and Doukkala : Moroccan Atlantic margin
clay, bsaltes, limestone and carbonate, evaporite of 4 drills are analysed
( geochemirstry of radionucléides, oil and gaz research)
III. Black Oil Shale samples from M layer of Timahdit :
sorption and sequential extraction of natural radionuclides mainly U .
7
9. Disturbances
1. Oulad Abdoun Basin : Disturbance
The normal configuration of the phosphatic series is from time to
time disturbed by structures which modified the usual succession of
the levels phosphatic.
What are the levels of radionuclides (U) in this matrix?
9
10. II. BlackOil Shale of M.L. Timahdit III. Mesozoic basins essaouira-Abda- Doukkala
Map of oil Shale of Timahdit Geological Map of Mesozoic deposits
10
11. The Timahdit blackoil shale
- 42 billion tons of oil shale / 15 billion barrels of
oil in place.
- four lithological layers (T, Y, X and M),
correlated throughout the deposit. Total area 350
km ²
11
12. - Fakhi and al, géochimie des
forages OYB-1 et NDK-2
Lithostratigraphic columns and sample location of boreholes
OYB-1 and NDK-2 (Mesozoic deposits)
12
13. Radiochemical procedures
- gamma and alpha spectrometry, ICP-MS
- The thin alpha sources were prepared by chemical
electrodeposition of U and Th and by sorption of Ra on MnO2
coated polyamide discs.
- U and Th were separated by using the ion-exchanges
chromatography before their deposition.
- An other method was carried out by using alkaline fusion by
LiB4O7 and LiBO2, of U and Th determination in sediment
samples.
<<The proposed methods have been applied for U, Th and Ra
isotopes determination in the sedimentary rock: phosphate and
black shale and coastal of Paleozoic and Mesozoic
sedimentary rocks, and Leach solutions >>
13
14. I. Phosphates from Oulad Abdoun Basin :
Morphological characterization by SEM
The majority of the par ticles
(seed phosphated, coprolithe
and of the osseous remains),
present angular forms with
sizes estimated between 3 and
700µ m.
The semi-quantitative
composition of the phosphate
par ticles was determined by
SEM-EDXS, shows contents of
Ca, O, Si and P and Fe, Al, Mg,
Na, F and S.
Morphology of the grains of the phosphatic series 14
15. X-rays diffraction analysis
.
- phosphate sample mainly contains
fluoroapatite carbonated of general
Ca 5(PO 4)3F
formula:
40
Ca10− z ( PO4 ) 6− x CO3− x F2+ x − 2 z
35
.-
- The matrix contains, moreover other
Ca Mg(CO 3)2
Ca Mg(CO 3)2
30
forms such:
Ca10 ( PO4 ) 6 F2 Ca10 ( PO4 ) 6 OH 2
25
Intensité
Ca 5(PO 4)3F
Ca 5(PO 4)3F
20
Ca 5(PO 4)3F
Ca 5(PO 4)3F
Ca 5(PO 4)3F
Ca 5(PO 4)3F
Ca Mg(CO 3)2
Ca 5(PO 4)3F
SiO2 ( Ca, Mg )( CO3 ) 2
Ca 5(PO 4)3F
CaCO 3
Q Q
15
CaCO 3
Ca ( Mg 0,5 Fe0,5 ) ( CO3 ) 2
Q Q
10
CaCO 3
Q
CaCO 3
5 Q
Q Q
Q
0
10 15 20 25 30 35 40 45 50 55 60 65 70
2theta
- mudstone, organic matter and the
trace éléments
15
17. Concentration : U and Th (alpha spectrometry), the stable by ICP-MS
17
18. 238
U, 235U , 234U in Bq/Kg as a function of depth
-The figure shows that
very observable change
between the concentration of
234
U in phosphates and
mainly limestones facies.
18
19. Activity Ratio 234U / 238U and desequilibrium
2
234 U/ 238 U
230 Th/ 238 U
1
8 9 10 11 12 13 14 15 16 17 18 19 20 21
PROFONDEUR (m)
U/238U> 1: Interactions of mineral phases with fluids containing 234U
234
234
U/238U< 1 : the main process is the alteration of rock, damage essentially par alpha
recoil.
230
Th/238U: most important in determining the direction and magnitude of mobilization
230
Th/238U> 1 mobilization of U than for altered sample: 230 Th>238U>234U
19
230
Th/238U< 1 accumulation of U
21. contribution of 3 main particle size of phosphate
ores in total radioactivity
1. size separation by appropriate sieving (3 fractions):
- fine fraction(0.05 to 0.1mm): mainly clay and quartz
- medium fraction (0.1 and 0.5 mm): grains of phosphate
- coarse fraction (0.5 mm and 2.25 mm). fragments of shells of
invertebrates, vertebrate bone debris, coprolites, and aggregates of
grains weakly cemented phosphate (Sand fraction).
2. purpose of the analysis: in industrial phosphate, before traitement, an initial
Size séparation is effected:
1.A clay fraction
2.A sand fraction
3.Phosphate fraction
Contribution of each fraction in the total radioactivity???
21
22. Contribution of each fraction in the total radioactivity
Sample GT20 as example : sillon B, Ypresian age.
% /act 234
U/238U 230
Th/238U
238
U 230
Th 234
U
Crude
Samples
1279±146 1194±115 1229±141 0,96 0,93
coarse
201±21 121±13 180,96±19,1 15,71 0,90 0,60
fraction
Medium 79,67 0,94 0,78
1019±183 799±95 956,68±172,8
fraction
Fine 4,3 0,90 0,93
55±7 51±7 49,32±6,35
fraction
22
23. GT 12 and GT 20 (phosphate layers bound by marl) samples from Gahar tajer
phosphate ores : it correspond to detrital rock, porous, often layered,
consisting of grains bound by a cement
GT1- Wet phosphatic marl facies,.
Depht: 20,6m
Concentration of
238
U = 1456±7 Bq/Kg) or 117,98 ppm
GT12- Phosphate at the base yellowish
coarse coprolite very thin and marly roof, with
reddish oxidation and discrete laminations.
Depht: 13,5m
Concentration of
238
U = 1807±51 Bq/Kg)or 146,4ppm
23
24. II. The Mesozoic basins essaouira-Abda and Doukkala : Moroccan
Atlantic margin
Lithology of Depht (m) Age
samples U Bq/Kg
238
Dolomite 1170 25 (2.0 ppm)
limestone portlandian
Clay- 1893,8 Dogger 30 (2.4 ppm)
sandstone
Basalts 812 15 (1.2ppm)
upper Triassic
gray clay 350 Berrisian 7 (0.51 ppm)
24
29. Conclusion :
The research on compartment solid phase:
I.PHOSPHATES SAMPLES
Radiochemical analysis by alpha spectrometry shows that:
•The specific activities of the identified radionuclides are
independent depth of drilling.
•They seem to depend on the nature of the deposits and on the
processes of assimilation of appropriate radionuclides
•Radionuclides seem rather concentrated in the sediment of
phosphates.
29
30. Conclusion :
-The deposits are mainly of marine origin, and most of the calcareous
sediments are more or less altered.
- In this work, we have shown, moreover, through the use of isotopic ratios, that
the porous interface (limestone) is generally places of preferential alteration.
This phenomenon is elucidated by the fractionation of U from these sites and
their mobility to the lower layers.
- For the phosphate facies, the U content varies from 76 ppm to 181 ppm
(GT6).
- For the intercalated layers of limestone, the U content varies from 28 ppm to
122 ppm (GT8).
- The higher uranium concentration in GT6 and GT8 formations relative to
strata above and below results from the accumulation of phosphorites in this
area due to its leaching from above and redeposited below.
-The process is not uniform, various sections and various horizons have
accumulated more U than others.
- Marly sediments have U concentration equal to 72 ppm, whereas in the
marly argillite, it is 43 ppm.
- Analysis of these results shows that in despite of their degree of weathering,
30
limestones have an economic interest in the recovery process of U.
31. - The main mineral phases, implied in the retention of trace elements, are
quartz, clays, calcite and dolomite. Accessory minerals consist of pyrite,
hydroxyl-apatite, anhydrite, feldspars.
- uranium is highly enriched in the shale (55ppm). The actinide is
associated predominantly with humic acids in the +4 oxidation state , the
precursor of kerogen.
- It has been deposited under anoxic reducing environment.
- Carbonates and apatite contribute also to the retention of uranium.
- The same phenomena is obseeved for phosphate sediments
31
32. Conclusion :
-In rocks called << Disturbances >> which constitute a permanent obstacle to
the exploitation of phosphate ores contains 113 ppm of U.
- The study performed on the sample size of phosphate GT20, age
Ypresian (- 53 46 AM), shows that:
- The fine fraction(0.05 to 0.1mm): mainly clay and quartz contributes with
4.3% in the total uranium of sedimentary rock.,
- The medium fraction (0.1 and 0.5 mm): grains of phosphate has an
important contribution estimated at 79.67%,
- The coarse fraction (0.5 mm and 2.25 mm). fragments of shells of
invertebrates, vertebrate bone debris, coprolites, and aggregates of
grains weakly cemented phosphate (Sand fraction), participates with
15.71% to the total content of uranium.
32
33. - The low activity ratios of 232Th/238U confers to the sediment a marine
character for all analysed sediments (phsphate, oil schales, and
cenezoic one)
other
- the retention capacities of the black shale can be highlighted. Relevant
metals are actually retained most probably via some active interfaces,
resulting from an intimate association between organic matter and the
inorganic matrix, especially silicates
- The use of such black shale as a potential precursor of storage material
for future possible high level waste repositories is under investigation:
The adsorbents showed good properties; a specific area equals 270 m 2g-
1
and 600 m2g-1 (Patent)
33
34.
U, Th and Ra sorption kinetic by supports made from oil shale
U
Th
Ra
34
35. •Collaborators:
- Mixed Unit of Research between CNESTEN and UHIIMC
- Hubert Curien Multidisciplinary Institute t Strasbourg, France
- Applied Nuclear Physics University of Seville.-Spagne
•National Office Hydrocarbon Research.
• Creation of the International Network of Research on Interfaces
Solid / water.
- The international patent Contract with NANOTECH
•- -
INVESTMENTS society on TSN process (Mai 2007).
for your attention : for all information on the card carried out by Morocco:
mining, seismic exploration for petroleum, consult Activity report of the National
Office of Hydrocarbons and Mining (ONHYM-Morocco)
35
37. the sequential extraction protocol
1g of sample rock + 30 ml of dionized
water
-Agitation during 24h
-Centrifugation + washing two time by 2ml of water dionized
1st filtrate
-Cetrifugation
Residue of the 1st extraction +30 ml de
MgCl2(1mol/l)
Each filtrate -Agitation during 24h
acidified at pH
-Centrifugation + washing two time by 2ml of water dionized
< 1 with 2sd filtrate
concentrated
hydrochloric -Cetrifugation
Residue of the 2sd extraction + 30ml of
acid and (CH3 COONa 1M, CH3COOH 1M)
stored at 4°C -Agitation during 24h
for analysis
-Centrifugation + washing two time by 2ml of water dionized
3rd filtrate
-Cetrifugation
Residue of the 3rd extraction + 35ml of
(NH2OH 0.04M, C2H3OOH 25%)
-Agitation during 24h
-Centrifugation + washing two time by 2ml of water dionized
4td filtrate
-Cetrifugation
38. Residue of the 4th extraction is calcined at
450°C during 2 h
The calcined Residue of the 4th extraction
25 mL 30% H2O2 –15 mL 0.02M HNO3 (pH=2)
15 mL 30% H2O2 – 9 mL 0.02M HNO3 (pH=2)
+(CH3COONa 3.2M, HNO3 20%)
-Agitation during 24h
the sequential extraction protocol
th
filtrate -Centrifugation + washing two time by 2ml of water dion
-Cetrifugation
Residue of the 5th extraction is Calcinated and
attacked by HCl and HF
Notas do Editor
-Le détecteur qui délivre les impulsions électriques à la suite de chaque détection de rayonnement Gamma. L’efficacité relative du détecteur utilisé dans ce travail, est de 30%, sa résolution est de 1,8 Kev. - Un générateur délivrant une haute tension au détecteur, qui est de 5000V positive. - Le préamplificateur qui a pour rôle la mise en forme du signal. - L’amplificateur , sa fonction est d’amplifier et de mettre en forme les signaux délivrés par le P.A. - ADC (Analogue Digital Converter), permet de convertir le signal analogique en provenance de l’amplificateur en un signal logique lisible par la carte d’acquisition. - MCA est la carte d’acquisition d’enregistrement et d’affichage des spectres permettant leur dépouillement.
We have been applied Sequential extractions using extractants with progressively increasing extraction capacity . The sequential extractions, described in this diagram, were performed under oxic conditions in constantly agitated centrifuge tubes, with a sample size of 1 g. After each extraction stage, supernatant was separated from the residue by centrifugation for 15 min and then filtrated through a 0.45 µm membrane filter into polypropylene bottles for analysis. Residue was rinsed twice with deionised water, hand shaken and separated by centrifugation and filtration . Each filtrate acidified at pH < 1 with concentrated hydrochloric acid and stored at 4°C for uranium determination by ICP-MS. The residue obtained at the last stage of the sequential extractions were ground, ashed at 850°C during 2 h and completely dissolved by alkaline fusion.
