Effect of mineral constituents in the bioleaching of uranium from uraniferous sedimentary rock samples, Southwestern Sinai, Egypt

• Aspergillus niger and Aspergillus terreus are the only isolates achieved highest leaching efficiency of uranium from the studied samples.
• Bioleaching process directly related to variations in mineral constituents and uranium grades.
• The optimum conditions of uranium bioleaching from its ores, were found to be 7 days, 3% pulp density, pH 3 and 30 °C.
• A. niger and A. terreus organic acids play an important and effective role for uranium leaching process.

Bioleaching, like Biotechnology uses microorganisms to extract metals from their ore materials, whereas microbial activity has an appreciable effect on the dissolution of toxic metals and radionuclides. Bioleaching of uranium was carried out with isolated fungi from uraniferous sedimentary rocks from Southwestern Sinai, Egypt. Eight fungal species were isolated from different grades of uraniferous samples. The bio-dissolution experiments showed that Aspergillus niger and Aspergillus terreus exhibited the highest leaching efficiencies of uranium from the studied samples. Through monitoring the bio-dissolution process, the uranium grade and mineralogic constituents of the ore material proved to play an important role in the bioleaching process. The tested samples asserted that the optimum conditions of uranium leaching are: 7 days incubation time, 3% pulp density, 30 °C incubation temperature and pH 3. Both fungi produced the organic acids, namely; oxalic, acetic, citric, formic, malonic, galic and ascorbic in the culture filtrate, indicating an important role in the bioleaching processes.