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NUCLEAR POWER INDUSTRY IN POLAND: ANALYSIS OF URANIUM SUPPLY FROM LOW GRADE ORES

Paweł Bieluszka 1, Kinga Frackiewicz 1, Irena Herdzik-Konecko 1, Agnieszka Miskiewicz 1, Katarzyna Szczyglow 1, S. Wolkowicz 2,

Grazyna Zakrzewska-Trznadel 1 , Barbara Zielinska 1

1 Institute of Nuclear Chemistry and Technology Dorodna 16, 03-195 Warsaw, Poland 2 Polish Geological Institute, Rakowiecka Street 4, 00-975 Warsaw, Poland

k.frackiewicz@ichtj.waw.pl

INTRODUCTION

According to draft of Polish Nuclear Power Program published in 2010, the

first nuclear power plant in Poland is expected to be put in operation around the

year 2020. One of the basic issues of this program is to establish scientific

support for first nuclear power plant in Poland and provide necessary analyses of

available domestic uranium resources in the country. Thereby, two Polish

Institutes: Institute of Nuclear Chemistry and Technology and Polish Geological

Institute have taken into realization the project financed partly by European

structural funds: “Analysis of the possibility of uranium supply from domestic

resources”. The main objectives of the project are: to assess the possibility of

exploitation of uranium resources in Poland, and to work out the methods of

uranium extraction from the ores and production of the yellow cake - U3O8. The

industrial wastes and by-products from copper and phosphorous fertilizer

industries, as a potential uranium sources, are also taken into account. The

technological scheme of uranium extraction from the ore material consists of:

crushing, grinding, leaching (acidic or alkaline) and liquid-liquid extraction with

selected extracting agents.

The preliminary analysis of uranium supply from domestic resources was

carried out in 60-80s. The exploration of uranium deposits was stopped, due to

canceled plans of building Zarnowiec nuclear power plant. However, it is known

that apart from old mines operating just after the Second World War where

uranium was mined in Sudetes (Kowary, Podgorze, Radoniow, and Kopaliny-

Kletno) and Holy Cross Mountains (“Staszic” Mine in Rudki); the new deposits

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are possible for exploitation [1]. The most perspective are low-grade Lower

Ordovician Dictyonema black shale discovered in Polish Lowland, in the area of

Podlasie Depression (Rajsk, NE Poland) and Triassic sandstones from Peribaltic

Syneclise (Krynica Morska and Paslek) [2-5], where concentration of uranium

locally reaches 1.5%. Concentrations of uranium in the black shale of Podlasie

region are rather low [6]. Petrographic, mineralogical and chemical studies of the

ores will allow elaborating the optimal processing technology and selecting the

appropriate methods for uranium extraction.

CHARACTERISTICS OF ORES

The ores for experiments: dictyonemic shales and sandstones were

obtained from Rajsk Deposit and Krynica Morska Deposit, respectively. The

analysis of uranium concentration from selected boreholes (Rajsk) showed the

big diversity of uranium concentration in vertical profile (Fig.1). The preliminary

analysis of sandstones reported that these ores are very promising.

Fig. 1. Dictyonema shale sample from Rajsk Deposit (Podlasie Depression). LEACHING OF URANIUM FROM DOMESTIC ORES

The five different samples were chosen to study, with content of uranium

from 89 ppm to 142 ppm (Tab.1).

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Table 1. The content of uranium in uranium ore samples.

Sample notation

Deposit notation

U ppm

3224 Rajsk JG-1 89 3227 Rajsk JG-1 121 3226 Rajsk JG-1 123 3233 Rajsk JG-1 142 3276 Hacki JG-5 106

EXPERIMENTS

At the beginning the representative samples of ores were selected. These

samples were crushed, grinded and then, they were classified into five fractions

in the particle size range <0.2mm-1mm. The samples were calcinated in the oven

at temperature 550°C during 4 hours. The leaching w as carried out with

calcinated and non calcinated samples using 5% and 10% sulphuric acid and

additionally, with prior “acid cure” by concentrated 48% and 96% sulphuric acid.

The experiments were performed in two experimental set-ups: in the

round glass flask with the agitator (with addition of MnO2) at temperature of 80°C

during 8 hours under ambient pressure, and in the autoclave during 2 hours at

different temperatures and pressures (3, 5, 7 bar).

The obtained solutions were filtered and washed by distilled water. The

uranium concentration in post-leaching solutions was analysed by ICP-MS

technique. The ICP-MS analyses included the determination of concentration of

such metals like: U, V, Mo, Cu, Zn, Ni, La and Th.

The leaching of uranium from sandstones was carried out using the same

procedures like in the case of dictyonema shale samples.

RESULTS OF LEACHING

The results of acid leaching of uranium and another metals carried out in

the round glass flask were very satisfied. The average efficiency was between

64%-81% for uranium and for such metals like: V – 25-52%, Mo – 33-78%, Cu –

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28-52%, La – 31-66%, Th - 67-80% (Tab.2). The extraction of Zn and Ni was

almost complete.

Table 2. Efficiency of acid leaching of selected metals from five different samples.

Sample notation

Deposit notation

U [%]

V [%]

Mo [%]

Cu [%]

La [%]

Th [%]

3224 Rajsk JG-1 72 33 66 33 60 80 3227 Rajsk JG-1 64 30 51 29 59 78 3226 Rajsk JG-1 68 44 78 52 62 77 3233 Rajsk JG-1 78 25 59 41 66 67 3276 Hacki JG-5 81 52 33 28 31 76

The leaching of uranium and accompanying metals from the ores carried

out in the autoclave [7] was also efficient. The average recovery of uranium and

other metals from the ore sample denoted as 3227 was 61% and V and Cu about

30 % (Tab. 3).

The influence of pressure in the experimental range was not significant;

however the best leaching results were obtained at pressure of 5 bars. In these

conditions the leaching efficiency of uranium was about 65%, molybdenum 60%,

vanadium over 30% and lanthanum – ca. 65% (Tab.3).

Table 3. Efficiency of acid leaching of 3227sample.

pressure Extracted

metals ambient

pressure

3 bar 5 bar 7 bar

U [%] 64 60 65 58

V [%] 30 29 33 30

Mo [%] 51 58 58 56

Cu [%] 29 28 35 26

La [%] 59 58 63 63

Th [%] 78 75 82 70

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Comparison of all results obtained for uranium solid-liquid extraction

showed that the leaching the ores can be carried out under ambient pressure

also with good efficiency.

The influence of particle size in the tested size range was not evident.

LIQUID-LIQUID EXTRACTION OF URANUM

The next stage of uranium production from ores is recovery of this metal

from post-leaching solution. Different agents were tested to extract uranium: di(2-

ethylhexyl) phosphoric acid (D2EHPA), tri-n-octylamine (TnOA),

tributylphosphate (TBP), trioctylphosphine oxide (TOPO), triethylamine (TEA).

The effect of extractant, sulphuric acid and uranium concentrations on the

extraction process from the model solution of uranyl nitrate was investigated.

The use of different reagents as strip solutions of the loaded uranium in

organic phase was also tested. It is described in the literature, that uranium can

be re-extracted from solutions of extractants by contacting with sodium carbonate

solution, ammonium carbonate solution, hydrochloric, sulphuric or fluoric acids

[8, 9].

EXPERIMENT

The liquid-liquid extraction was carried out with model solutions of

uranium. Solutions were prepared by dissolution of uranyl nitrates in sulphuric

acid to obtain concentrations: 0.2gU/L and 0.4gU/L. The organic phase was

kerosene with diluted extractants: di(2-ethylhexyl) phosphoric acid (D2EHPA), tri-

n-octylamine (TnOA), tributylphosphate (TBP), trioctylphosphine oxide (TOPO),

triethylamine (TEA). The concentrations of extractans used were 0.2M and 0.4M.

Liquid-liquid extraction experiments were performed by slow mechanical shaking

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of the tubes with two liquid phases at ambient temperature. The time of shaking

was from 2 to 45 min.

RESULTS OF LIQUID-LIQUID EXTRACTION

The liquid-liquid extraction experiments for different extractants showed

that the highest extraction efficiency was reached for extractants: tri-n-octylamine

and di(2-ethylhexyl)phosphoric, giving almost 100% recovery of uranium from 5%

sulphuric acid solution for different concentrations of uranium and extractans

(Fig.2, Fig.3). With TOPO recovery of uranium from aqueous solution was 90%

that means this extractant also can be taken into consideration as an eventual

extractant (Fig.2).

Plots (Fig.2, Fig.3) showed that extraction equilibrium of uranium by

various extractants from sulphuric acid solution was accomplished after few

minutes. The best concentration of sulphuric acid to obtain the highest efficiency

of uranium extraction was 5%. Increasing sulphuric acid concentration from 5%

up to 10% one can observe the effect of extraction efficiency decline, while

extraction efficiency increases with increase of extractans concentrations (Fig.4).

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30

time [min]

% E

TOPO TEA TnOA TBP

Fig. 2. The extractions efficiency of uranium (0,2gU/L in 5% H2SO4)

for different extractants (0.2M) in kerosene.

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0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50

time [min]

%E

TEA HDEHP TnOA

Fig. 3. The extraction efficiency of uranium (0,5gU/L in 5% H2SO4)

for different extractants (0.4M) in kerosene.

Fig. 4. The effect of sulphuric acid concentration on extraction of uranium by TnOA in kerosene.

0

20

40

60

80

100

4 5 6 7 8 9 10 11

[H2SO4] [%]

% E

0,2 g U/L 0,2 M TnOA 0,2 g U/L 0,4 M TnOA

0,5 g U/L 0,2 M TnOA 0,5 g U/L 0,4 M TnOA

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CONCLUSIONS

The preliminary studies of uranium extraction from indigenous resources are

rather promising. The average efficiency of uranium leaching from ore materials

was in the range of 64-81% for different samples. The leaching efficiency of other

metals was as follows: V - 24-52%, Mo - 33-78%, Cu - 28-52%, La - 31-61% and

Th - 67-80%. The extraction of Zn and Ni was almost complete. The best results

of acid leaching were found for 10% H2SO4.

The results of leaching in the autoclave did not show significant influence of

pressure. The influence of particle size in the tested size range (<0.2mm-1mm)

was not evident.

Two reagents: tri-n-octylamine and di(2-ethylhexyl)phosphoric acid are found

to be very good extractants for uranium extraction from post-leaching solutions.

The extraction efficiency of uranium by using these extractants was almost

100%. The extraction efficiency increased with the increase of extractant

concentrations while it decreased with the increase of sulphuric acid

concentration.

The first analysis of uranium in Lower Triassic sandstones from Peribaltic

Syneclise showed that these deposits are very prospective.

The technological part of the project will be completed with technical and

economical analysis.

ACKNOWLEDGEMENT The studies are supported by PO IG 01.01.02-14-094-09-00 research grant: “Analysis of the possibility of uranium supply from domestic resources”. REFERENCES [1] M. Niec, Polityka Energetyvzna, Tom 12, zeszyt 2/2 2009. [2] J. Kanasiewicz, M. Sałdan, J. Uberna, Biuletyn IG, 1965, vol. 5, p. 171-205. [3] J. Borucki, Z. Głowacki, W. Masłowski, M. Sałdan, J. Uberna, W.

Zajączkowski, PRACE IG. Wyd. Geol. Warsaw. [4] E. Bareja, S. Przeniosło, 1986 NOT SIiTG Warsaw, p. 19-39. [5] S. Wołkowicz, R. Strzelecki, 1993, CPPGSMiE PAN, p. 191-199.

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[6] G. Zakrzewska-Trznadel, K. Frackiewicz, B. Zielinska, I. Herdzik-Konecko, P. Bieluszka, A. Miskiewicz, Katarzyna Szczyglow, S. Wolkowicz, Anual Report: in press

[7] V.V. Shatalov, S.A. Pirkovski, K.M. Smirnov, Atomic Energy, 2007, Vol.102, No. 2, p. 147-150

[8] J.A. Daoud, M.M. ZEID, H.F. ALY, Solvent Extraction and Ion Exchange, 1997, Vol. 15, No. 2, p. 203-217. [9] S. Khorfan, O. Shino, A. Wahoud, A. Dahdouh, Periodica Polytechnica Ser. Chem. Eng., 2000, Vol. 44, No. 2, p. 123-132.