Processing of the mineralized Black Mica for the recovery of uranium, rare earth elements, niobium, and tantalum

Abstract

The mineralogical studies on Black mica raw material revealed the presence of notable high radioactive minerals such as uranium minerals (Soddyite, Uranophane, Uranothorite, and Ishikawaite), niobium - tantalum minerals (Columbite and Plumbopyrochlore), and rare earth elements minerals (Allanite, Xenotime, and monazite). From mineralogical and chemical studies make it possible to determine optimal processing conditions, the preferred lixiviate option, and the required costs. Black mica sample was found to assay 1680 mg/Kg U, 5000 mg/Kg REEs, and 50,750 mg/Kg Nb while Ta not exceeds 5000 mg/Kg. Through applying sulfuric acid agitation leaching, 92% of uranium was dissolved under optimum leaching conditions of: 8% concentration of H2SO4 acid, 1/4 solid/liquid ratio at room temperature for 4 h reaction time, while RE2O3, Nb2O5 and Ta2O5 remained in the unattacked residue. A phosphate mixture was used for rapid dissolution of refractory minerals, REEs, Nb and Ta minerals, after fusion, which give 97.8%, 99%, and 97%, respectively, leaching efficiencies. Ion exchange, solvent extraction and precipitation techniques were used for separating and recovery of U, REEs, Nb, and Ta species from their leach liquor.