El Missikat Research Articles

Using of uranium and thorium isotopes in age framework determination for different stages of alterations and mineralizations in Missikat altered granites, Central Eastern Desert, Egypt

El Missikat area represents one of the most important uranium occurrences in the Eastern Desert of Egypt. Ten samples from altered granite and jasper vein are collected and uranium-thorium isotopes analyzed radiochemically by alpha spectrometry. Different thorium/uranium isotopic activity ratios were calculated in the collected samples which were below the chondritic ratio due to enrichment in uranium or removal of thorium, suggesting that other processes rather than charge and radius play the important role in mobilization of these elements. All the specific activities of 238U and 232Th in the studied rocks have values higher than the average permissible limits. 234U/238U activity ratio >1, 230Th/234U and 230Th/238U < 1 in the studied rocks indicated the prevailing of reduction conditions during uranium deposition and these rocks are considered as a site for uranium deposition. 238U/235U and 234U/235U activity ratios were slightly positively and negatively deviated from the natural, indicating the effect of alteration processes. Estimation the age of uranium deposition clarified that the age of uranium deposition of El Missikat silicified granites vary between 12.59 ± 0.46 and 40.07 ± 0.66 ka with 27.99 ± 0.53 ka as an average, while the age of uranium deposition in the desilicified granite of El Missikat ranged between 22.76 ± 0.53 and 48.2 ± 0.50 ka with an average 34.06 ± 0.51 ka. Age of uranium deposition in jasper vein is 28.23 ± 0.52 ka. The recorded age of uranium deposition in El Missikat granites and silica vein indicate the desilicification is the oldest alteration process and the silicification is the youngest.

Distribution and Bioaccumulation of Uranium and Thorium in Natural Soil and Wild Plants of Wadi El-Missikat, Central Eastern Desert, Egypt

Uranium and thorium concentrations were determined in soil and wild plant samples collected from Wadi El Missikat, Central Eastern Desert, Egypt. The U and Th contents are similar to those in Gebel Qattar soil (North Eastern Desert, Egypt) but higher than their corresponding levels in the Earth’s crust. The results obtained indicate that the Fagonia boveana plant uptakes and accumulates both elements but uptakes of Th is higher than for U. Fagonia sp. can absorb and accumulate uranium element with 150 times more than the average of world plant uptake. The Zilla spinosa plant was also found to be hyper-accumulator for U and Th and can absorb and accumulate uranium with 48 times more than the average world plant Analyses of the studied plants show that they are considered as hyper-accumulators for uranium and thorium and could be used as candidates for exploration for these elements and phytoremediation of radionuclide-contaminated soils.

Radiological assessment of gamma and radon dose rates at former uranium mining tunnels in Egypt

Radiological assessment was carried out at the mining tunnels (El Missikat and EL Aradiya tunnels) in Egypt due to exposure to radon (222Rn), thoron (220Rn) and gamma radiation. 222Rn/220Rn measurements were carried out with two techniques; instantaneous (active) and discriminative (passive) radon and thoron solid-state nuclear track detectors were used for longer representative measurements. The detectors were exposed for a long time inside the tunnels. The results showed that radon and thoron in general, are very high due to non-ventilation drafts inside the tunnels and gamma radiation was low. The total annual effective doses exceeded the permissible limit 20 mSv year−1. According to IAEA recommendations, the two tunnels are regulated and controlled areas. A radiation hazard could be associated with exceptional situations, such as elevated exposures to ionizing radiation at tunnels, so work within these tunnels must be prevented until the application of IAEA regulation for radiation protection standards. The exposure for radon and thoron gases for a long time can damage the body cells and cause cancer.

Chemical Treatment of El Missikat Fluorite-Bearing ore Material, Egypt, for Recovery of Pure Yttrium Oxide

El Missikat fluorite-bearing ore material, Eastern Desert, Egypt, has been identified as containing a quantity of heavy rare earth elements (REE) such as yttrium fluorite mineral. Rare earth concentrate prepared from sulfate solution of El Missikat fluorite- bearing ore material assays 0.615% of REE. The solution was prepared from ore material by two subsequent thermal steps namely; fluorine deactivation by MgO and roasting by (NH4)2SO4.The deactivated roasted matrix was leached with hot distilled H2O to prepare the solution which assays 0.846g/L of REE. This solution was treated with 20g of oxalic acid to produce impure RE oxalate cake which was ignited at 950oC. It was then dissolved in concentrated HNO3 to prepare the RE nitrate solution for extracting yttrium using tri butyl phosphate (TBP) in kerosene. The produced yttrium oxide was of 97.2% purity.

Gamma activity of stream sediment feldspars as ceramic raw materials and their environmental impact

In situ gamma spectrometric measurements have been performed to characterise the natural radiation that emitted from the stream sediment feldspars in Wadi El Missikat and Wadi Homret El Gergab, Eastern Desert, Egypt. The measurements of potassium (K, %), equivalent uranium (eU, ppm) and equivalent thorium (eTh, ppm) were converted into specific activities and equivalent dose rate. The average specific activities were 1402 Bq kg(-1) for K, 113 Bq kg(-1) for eU and 108 Bq kg(-1) for eTh in Wadi El Missikat, while they were 1240, 104 and 185 Bq kg(-1) in Wadi Homret El Gergab. The calculated outdoor average effective dose rates was 1.1 mSv y(-1) in wadi El Missikat and 1.3 mSv y(-1) in Wadi Homret El Gergab. The terrestrial-specific activities and effective dose rate levels of the natural radioactivity in the two areas lie within the international recommended limits for occupational feldspar quarry workers. On the other hand, these results indicated that irradiation is higher than the allowable level for members of the public. Therefore, quarrying the feldspar sediments from these locations as ceramic raw materials may yield an undesired impact on the environment, especially through the indoor applications.

Use of alpha spectrometry for analysis of U-isotopes in some granite samples

The present study aims to use the a-spectrom- etry, at NMA. A radiochemical technique (1, 2) for analysis of U-isotopes was carried out for some granite samples from Gabal Gattar and El Missikat localities and also for some reference soil samples of IAEA. Several steps of sample preparation, radiochemical separation, and source preparation were performed before analysis. The concerned sample was leached by HNO3, HF and H2O2 acids after ashing. The ashed sample was spiked with uranium tracer ( 232 U) for chemical yield and activity calculation. Then uranium was extracted from the matrix elements with tri- octylphosphine oxide (TOPO) and stripped with 1 M NH4F/0.1 M HCl solution. The uranium fraction was purified by co-precipitation with LaF3 to ensure complete removal of thorium and traces of resolution degrading elements. This was followed by a final clean-up step using an anion exchange. The pure uranium fraction was elec- trodeposited on a stainless steel disc from HCl/oxalate solution. The obtained results from the soil reference samples indicate general similarities between the tech- niques of a-spectrometers of NMA, EAEA and IAEA for analysis of U-isotopes. The U-isotopes in the granite samples of high radioactivity levels need more attempts after dilution process to be in the limit detection of a-spectrometry.

Correlation Study on the Geology and Radioactivity of Surface and Subsurface Working at El Missikat Area, Central Eastern Desert, Egypt

Correlation Study on the Geology and Radioactivity of Surface and Subsurface Working at El Missikat Area, Central Eastern Desert, Egypt

Occurrence of Uraniferous Iron Grains at Gabal Gattar, El Missikat and El Erediya Granites in Eastern Desert of Egypt

AbstractUraniferous iron grains occur in some radioactive granite plutons in the Eastern Desert of Egypt. Modal analysis of these grains indicates that weight abundance of uraniferous grains amounts to 17.50%, 18.00% and 26.00% of the total accessory heavy minerals of the uranium‐mineralized samples of Gabal Gattar, El Missikat and El Erediya, respectively. These grains are mainly restricted to shear zones associated with strong hematitization, and occur either as fracture fillings or as interstitial grains among the main rock‐forming minerals. Uraniferous iron grains are mainly composed of uranophane and β‐uranophane coated and stained with limonite. These grains represent the main radioactive minerals in addition to the bright canary yellow to yellow uranophane and β‐uranophane mineral grains. The data obtained on scanning electron microscopy and electron microprobe analysis confirm the abundance of iron in the darker colored varieties with respect to the light colored varieties. This mode of occurrence of the uranium minerals requires special consideration during mineral processing by physical means.

Ground geophysical study for development and exploration of El Missikat radioactive minerals prospect, central Eastern Desert of Egypt : E. M. Elkattan, H. S. Sadek, S. I. Rabie & H. I. Hassanein, Nuclear Geophysics, 9(4), 1995, pp 363–382

Ground geophysical study for development and exploration of El Missikat radioactive minerals prospect, central Eastern Desert of Egypt : E. M. Elkattan, H. S. Sadek, S. I. Rabie & H. I. Hassanein, Nuclear Geophysics, 9(4), 1995, pp 363–382

Natural radioactivity of granite rocks in Wadi Qena

Compressed powdered granite samples brought from G. El Missikat and G. El Garra with different ages were analyzed by low-level γ spectrometry. The contents of U, Th and K were determined and the dependence on age was tested. U/Th and U/K ratios for young and old granite samples were evaluated. Results were discussed and compared with other experiments.

Technical note Application of autocorrelation function to structural lineaments in radioactive sample area in the central Eastern Desert of Egypt

Abstract Most of the methods used by field geologists to represent measured structural lineaments assume that the variable is random and disregard the relationships which link them in distance and direction. This article is concerned with the application of the autocorrelation function analysis to structural lineaments as measured from aerial photos, over the granite pluton of Gebel El Missikat in the Eastern Desert of Egypt. The results of such statistical analysis are compared with those of the traditional methods of stereonets and found to be generally coinciding but more definitive and clearly identify the poor trends. Also, they explain the relation between the resultant structural trends and the existing tension and shear planes. Thus the applied method, which is commonly used with magnetic data (Meleik 1982), overcomes the difficulties met with in interpreting the structural points of any investigated domain.

Distribution and orientation of radioactive veins in the El Erediya-El Missikat area, Central Eastern Desert, Egypt

Abstract Abstract. Geological and radiometnc investigations for radioactive materials in the Wadi Alalla area revealed the presence of some uranium-mineralized veins in pink granite rocks forming the prominent masses of Gebel El Erediya and Gebel El Missikat. These veins are mostly composed of siliceous material showing some variations from proper silica or jasperoid veins to ferruginous and siliceous mylonites filling some fracture zones. However, not all siliceous veins in these granite masses are mineralized or radioactive. This paper deals mainly with the distribution pattern of the radioactive veins associated with the granite masses of Gebel El Erediya and Gebel El Missikat, their characteristic geological features and geometry, as well as their relationship with the major structural features of the Wadi Atalla area. It has been found that most of the radioactive veins in El Erediya pluton are of the fracture-filling type, predominantly of a NNW-SSE trend. The similar radioactive veins in El Missika...

Structural analysis of the main uraniferous chalcedony vein at G. El Missikat environs, Central Eastern Desert, Egypt

Abstract This study deals with the structural analysis of joints in the uranium-bearing vein deposits and the surrounding enclosing granite rocks in G. El Missikat pluton, Central Eastern Desert, Egypt. The study includes the different structural features such as the intensity of joints, their opening and length for the different sets taken on a systematic pattern through and along the upper and lower contact of the uraniferous chalcedony vein, and their correspondence in the subsurface mining working. The relative movement of the chalcedony vein is interpreted from slickensides striation along the enclosing fault plane. The analysis of microfolds along the fault planes also indicates the movement picture. Photolineaments are traced showing the main fracturing intensity trend in the granite pluton. The study reveals that the main fracturing surface sets trend ENE-WSW and NW-SE stained by surface uranium mineralization. The first set in the subsurface mining working is found rotated anticlockwise relative ...