The Egyptian Placer Deposits- a Potential Source for Nuclear Raw Materials
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EG9601646 Second Arab Conference on the Peaceful Uses of Atomic Energy, Cairo 5-9 Nov. 1994 AAEA The Egyptian Placer Deposits- A Potential Source for Nuclear Raw Materials Gooda A. Dabbour Nuclear Materials Authority, Cairo, Egypt. /0,04c /0,06 i /6,04j ^j-jjilj^ J \ • M^1 /0,48 LfLe. CJ-JJL 6,31 l 98,64 ^^Lfe JJ^J^JI JOJL-O ^J^A-JJ ^j^liL^JIj ^J^JI^JJJI ^ > j • .• <?1 Abstract Extensive black sands placer deposits are discontinuously distributed along the northern Mediterranean coastal plain of the Nile Delta as well as Sinai Peninsula i.e. in the coastal stretch between Abu Qir town to the west and Rafah city on the eastern Egyptian Frontiers. These sediments contain strategic and economic heavy minerals which are required for the industrial exploitation whether for nuclear industry or other metal- lurgical and engineering industries. The mentioned deposits comprise huge reserves of the six heavy economic minerals which include mona- zite, zircon, rutile, ilmenite, magnetite, and garnet. 191 The first three economic minerals namely monazite, zircon, and rutile contain uranium, thorium, zirconium, hafnium, titanium as well as rare earth elements, thus monazite, which is a rare earths-thorium anhydrous orthophosphate assays 0.48% U3O8, 6.04% Th O2, and 61.31% RE2O3. Egyptian beach zircon which is a zirconium silicate mineral contain 67.06% (Zr+Hf) O2. Traces of uranium assays from 0.04% to 0.11%. U3O8, while its thorium content varies from 0.02% to 1.19% Th O2. The beach rutile is almost a puretitanium dioxide assaying up to 98.64% TiO2- Therefore, the geological reserves of the nuclear materials were estimated to reveal enormous reserves. In the light of these data, the Nuclear Materials Authority has established a plant for the exploitation of the Egyptian placer deposits at Rosetta area to produce monazite, zircon, and rutile concentrates. The monazite concentrate will be processed for the production of uranium, thorium, and rare earth oxides cakes, while zirconium, hafnium, uranium, and thorium oxides could be extracted from the zircon concentrate. Titanium dioxide for nuclear industry and paints could be produced from the rutile concentrate. In the mean time zircon as a mineral would be used in ceramic industry whereas rutile as a mineral would be used in welding rods industry. Besides, the rare earth oxides cake could be used in ferro-silicon alloys. 1- Introduction The Egyptian black sands placer deposits on the Mediterranean Coastal Plain contain many mineral species as they have been derived from igneous and metamorphic rocks [1]. Many studies were carried out dealing with the mineralogical composition, grain size distribution, origin of the sediments as well as their economic considerations [1 to 25]. The mineral constituents include six heavy economic minerals; namely magnetite, ilmenite, monazite, zircon, rutile and garnet. Monazite, zircon and rutile minerals do contain a number of elements necessary for the nuclear industry e.g. uranium, thorium, zirconium, hafnium, titanium and rare earths elements. Thus, the evaluation of these raw materials in the Egyptian blacksands placerdeposits would be calculated on the basis of the reserves of monazite, zircon and rutile mineral content in four localities along the Mediterranean Coastal Plain; namely Rosetta, Baltim, Damietta and north Sinai. 192 2- Geology Since the Late Miocene [26] and before the completion of the High Dam in May 1964, the River Nile was discharging huge quantities of sediments during the annual flood seasons in the Mediterranean Sea. These sediments were the final products of the disintegrated materials from the two main drainage areas of the Nile Basin which cover an area of about 3,000,000 km2 i.e. The Equatorial Plateau (igneous rocks) and the Ethiopian Plateau (metamorphic rocks). The River Nile poured its load in the Mediterranean Sea either by the to-day Rosetta and Damietta distributaries (Fig. 1 ) or through the seven old extinct Nile Branches. Ball [27] described the courses and the outpourings of the seven old extinct Nile Distributaries and stated that the outpourings were located in the coastal plain area that extend between Idku openning and El Farama east of Port Said (Fig.2). In other words, the black sands deposits are distributed along the Mediterranean Coastal Plain in the sector extending between Abu Qir town to the west and Rafah city on the Eastern Egyptian frontiers (Fig. 1).These sediments are now present either as beach deposits or in the form of coastal plain sand dunes. The high grade black sands are associated with the outpourings of the Nile Distributaries whether the present or the extinct ones. The reserve estimation of monazite, zircon and rutile minerals will be carried out at the two locality related to the to-day Rosetta and Damietta promontories and two other locality related to the extinct Sebbenytic and Pelusaic estuaries. The study will include both beach sediments as well as coastal plain sand dune£. 3- Reserves Estimation The four chosen localities for geological reserve evaluation for monazite, zircon and rutile are considered to be the principal black sands deposits. The first locality is on both sides of Rosetta promontory. It extends from Idku Lake outlet to El Burrullus Lake openning. This stretch is about 70 km long and its width varies from about 200 m to about 5000 m with an average width of about 800 m. The area is characterized mainly by beach deposits except west Rosetta outpouring sector which has coastal plain sand dunes. The depth of the black sands in this area reaches about 9m. Beyond this depth, the sand fraction decreases to be less than 40% while the clay fraction constitutes the 193 major percentage. Above the mentioned depth, the sand fraction generally exceeds 60% of the sediments. The second locality is the coastal plain sand dune belt in which the heavy minerals content reaches up to about 35% and covers the area from Burg El Burrullus village eastward to El Gharbia Main Drainage, a stretch of about 15 km long and average width of about 800m. The height of the sand dunes in this area reaches up to 15m, however, an average height of 5m will be considered. Assuming that the beach sediments under the sand dunes reach about 10m depth, the thickness of the deposit in this area will be considered as 1 5m. The third locality is the north western part of El Manzalla Lake and the beach area just east of Damietta outpouring. The depth of this deposit will be 10 m and the area is about 30 km2. This area is characterized by a series of parallel sand bars called "Barr" trending generally northwest and are separated by longitudinal lagoons called "Tawal". The mechanism of formation of these parallel sand bars was attributed by Said [281 and Hamama [291 to be the result of the accretion of the bottom sediments of the continental shelf by the wave action and the continuous accumulation of these sands till the sand bar became exposed on the surface of the sea water leaving a longitudinal lagoon behind it. The last locality is the north Sinai coastal plain sector which extends between the eastern openning of El Bardawiel Lake at El Zaraniq in the west and El Arish town in the east. This stretch is about 20 km in length and about 500 m width It is characterized by beach deposits lined from the south by north Sinai sand dune belt [30]. The depth of the deposit in this area is about 10 m. In order to estimate the reserves of the black sands in the four localities and consequently the monazite, zircon and rutile mineral content, the apparent specific gravity of the dry sand used in the calculations must be 1.7 g/cm3 [31]. Also, the average frequencies of each of the monazite, zircon, and rutile minerals in the Egyptian black sands will be considered as 0.02%, 0.22% and 0.12% respectively. Due to the fact that Egyptian beach monazite almost belongs to one variety, its uranium and thorium contents do not vary greatly, on the otherhand, the uranium and thorium contents of zircon show great variation due to the presence of several varieties of beach zircon. The 194 existence of uranium and thorium in zircon is either due to defects in zircon structure or to inclusions of radioactive minerals like uranothorite. The coloured, cloudy, zoned (inclusions) and metamict zircon varieties contain more uranium and thorium than the colorless water-clear zircon varieties [32, 33, 34, 35 & 36]. Therefore, the different varieties of the Egyptian beach zircons were separated on the basis of their mass magnetic susceptibility. The obtained fractions were analyzed for their uranium and thorium contents. The U3O8, Th O2 and the frequency of each fraction were calculated and tabulated in table (1). From these values the average content was found to be 0.06% U3O8 and 0.04% Th O2. TABLE.I: FREQUENCIES OF MAGNETIC ZIRCON FRACTIONS AND THEIR U3O8 AND Th O2 CONTENTS. Current u3o8 ThO2 Frequency (amp) % % % 0.3 0.037 0.148 0.78 0.5 0.065 0.555 0.85 0.7 0.111 1.186 2.73 0.9 0.088 0.540 2.36 1.1 0.075 0.219 3.33 1.3 0.080 0.092 4.37 1.5 0.070 0.073 2.58 1.5 Non mag 0.046 0.020 82.28 The uranium, thorium, titanium, and rare earths elements contents in the Egyptian beach monazite were taken from the chemical assay given by Hammoud [ll]on 99.9% monazite concentrate. The adopted percentages of the nuclear elements in monazite, zircon and rutile used in the reserve calculations are shown in table (2).