Leaching and Extraction of Uranium from

the Red Silica Veins Intruding the

Younger Granites of Gabal Al-Aglab,

North Eastern Desert, Egypt.

By

Gamal S. Awadalla,

Nuclear Materials Authority

Example for radioactive

anomaly in japer vein at

Gabal Al-Aglab

A) Sketch B) isorad map

Sample

No. 9 10 11 12 13 14 Average

Trace elements (ppm)

Ba 215 199 320 405 212 202 258.83

Ce 12 25 54 27 11 26 25.83

Cr 86 78 93 49 67 99 78.67

Ga 62 79 57 77 51 71 66.17

Hf 12 10 15 16 17 22 15.33

La 19 32 48 37 30 27 32.17

Nb 10 22 16 19 32 24 20.50

Pb 99 109 121 138 154 114 122.50

Rb 72 55 74 63 53 51 61.33

Sr 81 86 93 96 101 89 91.00

Ta 23 26 29 19 24 27 24.67

Y 19 30 35 41 39 26 31.67

Cu 10 12 13 14 10 11 11.67

W 56 99 89 84 26 68 70.33

Zn 161 135 166 214 189 146 168.50

Zr 263 215 240 199 206 228 225.17

Th 112 183 169 206 159 168 166.17

U 512 830 644 590 811 843 705.00

Th/U 0.22 0.22 0.26 0.35 0.20 0.20 0.24

Fig. 1 Fig. 2

Fig. 4 Fig. 3

XRD pattern of separated heavy mineral fraction in jasper

(A) Alunogen, synthetic Al2(SO4)3, 17H2O

(P) Pahasapaite, synthetic (Ca, Li) 11 Li 8 Be 24 (PO4)24, 38H2O

(S) Scheelite, synthetic CaWO4

(H) Hematite, synthetic Fe2O3

-Jasper is the ultimate product of silicification of this granite in

which the minerals are progressively replaced by jasper.

-The silicified granite zone is surrounded by a zone of

kaolinized granite, which grades outwards into the fresh

granite.

-Jasper is commonly developed as fracture fillings associated

by hematitization in presence of both shearing and faulting

-The uranium content in jasper reaches to 843 ppm and

thorium content reaches to 206 ppm

-Geochemically, XRF and ESEM (Environmental Scanning

Electron Microscope) analyses show that the Gabal Al-Aglab

jasperoid rocks are enriched in Th, U, Zr, W and LREEs (Ce

and La)

Chemical Analyses of major oxides and trace elements

of jasper working samples

Trace elements,

ppm

Major oxides,

wt%

199 Ba 91.2 SiO2

9 Li 0.03 TiO2

22 Nb 2.42 Al2O3

109 Pb 4.86 Fe2O3

86 Sr 0.06 MnO

196 Th 0.61 CaO

830 U 0.11 Na2O

135 Zn 1 K2O

215 Zr 1.05 H2O+

0.03 CO2

0.02 SO2

101.39 Total

Grinding the ore to -60 mesh size (250 µm

•Sulfuric acid under proper leaching conditions was applied

•uranium was then extracted using the synergistic solvent mixture

of D2EHPA and TOPO in kerosene -

From the studied leaching parameters,

it can be concluded that for 90 % U leaching efficiency of G. Al

glab jasper veins,

the optimum conditions would include only 30 g/L H2SO4 in a S/L

ratio of 1:1 for 3 hours at room temperature.

-Iron and some other impurities were removed from the leach

liquor by precipitation at pH 3.5 using lime water

- Al Aglab leach liquor (1.5 gU/L)

Equilibrium data of uranium in D2EHPA (0.25M) in absence

and presence of TOPO from Al Aglab leach liquor.

TOPO,

M

Uranium, g/L Doa

Organic

phase

Aqueous

phase

0.00

0.02

0.04

0.06

0.08

1.11

1.14

1.35

1.43

1.41

0.39

0.36

0.15

0.07

0. 09

2.82

3.17

9.00

20.43

15.67

The molar ratio at synergism of about 4D2EHPA : 1TOPO in

kerosene would be considered optimum.

{0.25M D2EHPA: 0.06M TOPO}

McCabe-Thiele diagram of uranium extraction

from Al Aglab sulfate leach liquor

McCabe-Thiele diagram of Uranium Stripping

using 1M sodium carbonate as the stripping reagent.

Conclusion

Petrographical and mineralogical studies upon some

mineralized samples from Gabal Al-Aglab red silica veins

(jasper) indicated the presence of the secondary uranium

minerals uranophane and beta-uranophane besides zircon,

epidote and allanite and iron oxide minerals that play an

important role in uranium enrichment. Leaching studies of a

representative mineralized sample assaying 830 ppm U

resulted a leaching efficiency of 90 % under the determined

optimum conditions.

The latter involved 30 kg/t sulfuric acid in a S/L ratio of 1/1

for 3 hr at room temperature upon an ore material of grain size

of -60 mesh (250 µm). These conditions are more mild than

those used for comparable El Missikat and El Erediya

mineralized silica veins; a matter which might be due to the

partial presence of primay minerals.

The remaining unleached 10 % of input uranium in the

studied ore Al Aglab material might be due to their presence in

some refractory mineral (allanite and/ or thorite)

The leached uranium was recovered by the synergistic

mixture D2EHPA/ TOPO in kerosene after a prior purification

steps of the leach liquor through precipitation of impurities at

pH of about 3.5. Application of the McCabe- Thiele diagram

resulted in 3 extraction stages at a flow rate (O/A) of about 0.3.

For stripping, 1M sodium carbonate solution was used and

application of the corresponding McCabe- Thiele diagram

resulted in only 2 stripping stage at a flow rate (O/A) of about

2.15.