PROCEEDINGS: Nada et al. Follow up the leaching efficiency of uranium series from high-grade granite sample with high concentration of sulfuric acid A. Nada1, N. Imam2*, A. Ghanem1 1 Physics Department, Faculty of Women for Art, Science and Education, Ain Shams University, 11757, Egypt. 2 National Institute of Oceanography and Fisheries, Cairo, 11516, Egypt Keywords: Leaching efficiency, Granite sample, Sulfuric acid Presenting author, e-mail: [email protected] Introduction Materials and methods Uranium is the most representative actinide element that Sample preparation is of fundamental importance in the nuclear fuel cycle. The red granite sample from Gabal Gattar, the Northern Uranium is a naturally occurring radionuclide which has Eastern Desert (2352.8 ppm), was crushed and grinded 238 9 235 three isotopes ( U (t1/2=4.5x10 yr) 99.72 %, U into 63 mesh and then quartered to obtain representative 8 234 5 (t1/2=7.1x10 yr) 0.0055 % and U (t1/2=2.5x10 yr) sample. The mineralogical characterization of the granite 0.72 %. It has several oxidation states tetravalent and sample was done using X-Ray Diffraction (XRD) (Model hexavalent which dominant in the environment. D8 discover manufacture by USA). The sample is Hexavalent uranium is more dissoluble and mobile than measured by y-spectrometry, using an HPGe-detector to tetravalent uranium. Extraction of uranium is indeed determine the activity concentrations (Bq) of Uranium a hydrometallurgical operation in which uranium is isotopes (238U, 235U, and 234U), 230Th and 226Ra series. The directly leached first by suitable acid or alkaline reagents conditions of the leaching procedures were 50 g of sample, (Kraiz et al., 2016). Acid leaching is more widely used 98 % (H2SO4) acid concentration, 60 min stirring time, 1:3 than the alkaline one because of relatively coarse solid/liquid ratios at room temperature. The leaching preparatory grinding, comparatively mild reagent procedures performed with two methods to determine the concentration, shorter leaching times, applied under an leaching efficiency. After the leaching process, the ambient temperature and atmospheric pressure, the sample was filtered by using filter paper to get pregnant highest extraction efficiency, convenient for subsequent solution and the second method the sample without filter recovery processes (Kraiz et al., 2016; Nada et al., 2019). to get solution named total sample. Leaching mining is a new type of deposit mining technology that includes a solid liquid transfer process Analytical techniques transmitting useful elements from the ore to the leaching The leachate (pregnant solution) and total solution were solution. measured by an HPGe detector at interval time for more The granitic rocks constitute about 60% of the total than four months. The detector has a relative efficiency of neoproterozoic outcrops of the Eastern Desert of Egypt. about 50 % of the 3"x3" Nal(Tl) crystal efficiency, (El Gaby, 1975) classified the granites in Egypt into two connected to multichannel analyzer card (MCA) installed groups: (a) synorogenic granitoids, and (b) younger in a PC computer. The software program MAESTRO-32 granites, which include the post-orogenic pink and red was used to accumulate and analyze the data. The system granites. The younger granites of the Northern Eastern was calibrated for energy to display gamma photo peaks Desert found to be favourable for uranium mineralization between 63 and 3000 keV. The efficiency calibration was and showed significantly higher level of radioactivity performed by using three well-known reference materials (Kraiz et al., 2016). Gabal Gattar area was located at obtained from the International Atomic Energy Agency Eastern Desert, the west of Hurghada city at the Red Sea for U, Th and K activity measurements: RGU-1, RGTh- coast. The younger granites of G. Gattar are highly 1and RGK-1 (IAEA, 1987). Uranium-238 activity was fractured, sheared and subjected to hydrothermal determined in directly from the gamma rays emitted by its alteration processes. The U-mineralization at this daughter product 234mPa whose activity was determined occurrence are mainly related to presence of some from 1001 keV photo peaks (Sutherland and deJong, uranium minerals such as uraninite, pitchblende, 1990). The uranium-235 activity was determined directly uranophane, beta uranophane, clarkeite, zippeite, soddyite by its gamma ray peaks; 143.8, 163.4, 185.7, and 205.3 and kosolite as well as some U-bearing accessory and keV (Yucel et al., 1998). The 234U activity was determined secondary minerals like zircon, sphene, chlorite, fluorite from the gamma rays emitted from this nuclide at energies and iron-uraniferous grains (El-Galy et al., 2007). The of 53.2 keV and 120.9 keV (Yokoyama et al., 2008). main objective of the present investigation is studying Thorium-230 was determined from the 67.7 keV peak uranium leaching efficiency of granite sample with high (Simpson, and Grtin, 1998). The specific activity of 226Ra concentration of acid. In this type of study, Laboratory was measured using the186.1 keV from its own gamma- tests are used to evaluate a heap leach process using a ray (after the subtraction of the185.7 keV of 235U). The batch type of testing methodology. We attempt to follow specific activity of 214Pb was measured using the 241.9, up the leaching efficiency of uranium isotopes from high- 295.2keVand 351.9 keV while the specific activity of grade granite sample with high concentration of sulfuric 214Bi was measured using the 609.3keV. The activity acid at different interval time. concentrations of these radionuclides were measured by using the relation given in equation (1) (Bakr, 2014). 60 PROCEEDINGS: Nada et al. (1) Results and discussion where: Chemical analysis of Gabal Gattar granite sample Ai is the activity concentration of radionuclide (i) in The mineralogical composition of the granite sample has Bq kg-1, a good source for the alkali oxides (K2O + Na2O) B.RY is the emission probability of the gamma line contained in potash feldspar minerals (orthoclase and corresponding to the peak energy (Y) of radionuclide (i), microcline) and the sodic plagioclase feldspar mineral is the spectrometer's efficiency corresponding to the (albite) as shown in Table 1 and Figure 1. The chemical peak energy (Y) at the specific geometry, analysis of granite sample presented the major oxides of NsY is the net count under the peak area of the selected the sample Table 2. Oxygen and SiO2 were the main major gamma line for the measured sample, oxide of the studied sample and Al2O3 was the second t is the real counting time, and major oxide. The studied red younger granite M is the mass of the sample in kg. characterized enrichment in alkalis (K2O+Na2O) and The leaching efficiency of the radionuclides was albite. calculated according to the following equation: Leaching efficiency (%) = Activity concentration in leachate (Bq) / Activity concentration in the original sample (Bq) (2) I All.I Ca0.1 K0.27 Na0.63 08 Si2.9J\northodase ~ I Al K 08 SiJ Sankline t 02S! Quartzlow ~ I ~ . 8 1 ◄ Ca0 . 32 N a 0.1&O ◄ Sl1 , 1 84L a b4'tdoflte f AINa08Si3Albile I Al K0.89 Na0.11 08 Si3 MIClodine ~ I U i ~ 8 i I i ~~ . ) i ,,1•• ~•/1.. ~,-, ~ p, •> 1,, I 30 -~~~40 50 ! 60 70 80 " 20 2Thela (Coupled Twolhala/Theta) WL0 1.54060 Figure 1. The XRD diffraction pattern of granite sample. Table 1. The mineralogical characterization of G.Gattar granite sample. Compound Quartz Orthoclase Albite Microcline U Th Name low Wt (%) I 43.6 I 29.5 I 23.6 I 0.5 11 2.7 I 0.1 I Table 2. Chemical compositions of G.Gattar granite sample. Chemical Oxygen Na2O Al2O3 SiO2 K2O CaO UO2 ThO2 composition Wt (%) I 47.5 I 5.2 I 10.1 I 31.1 I 4.7 I 0.7 I 0.5 I 0.1 I Radiometric measurement context, 226Ra series has little changed from start point The activity concentrations of solid, leaching and total into 20 days and after that nearly slightly constant. This sample are shown in Table 3. In solid sample, there was may due to lower solubility of these radionuclides. From secular equilibrium between 238U and 226Ra and Figure (2, 3), it's obvious that, 230Th has highest activity disequilibrium with 234U that has the highest activity concentration which may be due to alpha recoil (Shiobara concentration. The sample indicated that preferential et al., 2017) and the solubility of 230Th increases in acidic abundance of 234U relative to 238U may due to prevailing aqueous solutions (Abdelouas, 2006). reducing conditions. The ARs of 234U/238U were higher than unity little In leaching sample, the activity concentration of 238U, changing from start until end of time as shown in Figure 230Th and 235U started increasing from start point into 4. This may be due to preferential release of 234U from 40 days and after that became slightly constant. On the damaged lattice sites produced bya-recoil atoms of 234U other hand, 234U has narrow change from start point to end during the leaching period (Bonotto et al., 2001; Andersen of time; we can say no change with the time. This may et al., 2009). However, due to different oxidation states, due to hexavalent uranium is more mobile at higher 234U forms more soluble U (VI) complexes and remains acidity, and tetravalent uranium will oxidize and convert in solution, while 238U present in the form of less soluble into hexavalent uranium. The 234U on the surface of the U (IV) complexes, precipitates (Pekala et al., 2010). The granite sample was dissolved quickly the leaching ARs of 230Th/238U were higher than unity started closed solution increased rapidly to its maximum. On the same into unity and increased with the time.