Correlation between bio- and classical techniques in uranium leaching of granite sample from Gabal Gattar, North Eastern Desert, Egypt

Abstract

ABSTRACT High-grade uranium granite ore was subjected to the biometallurgical and classical treatment to compare the uranium recovery. The high-grade uranium ore used in the experiments was collected from Gabal Gattar, Northeastern Desert, Egypt. The isolated Aspergillus niger from the studied sample was used for the indirect (using culture filtrate) leaching of uranium under different conditions. The effect of varying solid/liquid ratio (1/3, 1/5, 1/7, 1/10 and 1/15) and agitation time (30, 60, 90 and 120 min) was investigated and the leaching conditions optimised. The bioleaching of uranium achieved a maximum efficiency of 72% by the culture filtrate bioleaching at room temperature, agitation time 120 min with 1/10 solid/liquid ratio. A solution of sulphuric acid was used for the acid conventional leaching. The leachability of uranium under acid leaching conditions reached a maximum of 89% at room temperature, agitation time 90 min with 1/5 solid/liquid ratio and 50 g/l acid concentration. The two concentrates were analysed by SEM with EDX, which showed that U assay in the product amounted from bioleach liquor to 54.2% U which is higher than the product amounted from sulphuric acid (38.1% U). X-ray diffraction invistigations for the products of bio- and classical leaching indicate that the bioproduct is mainly composed of Potassium Uranyl Phosphate and Potassium Sulphate while coffinite, alite, hatrurite, calcio-olivine, uranium oxides and silica are the main components of classical leaching.