M. Nete

Primary beneficiation of tantalite using magnetic separation and acid leaching

Primary beneficiation was successfully performed prior to dissolution of manganotantalite (sample A) and ferrotantalite (sample C) samples obtained from two different mines in the Naquissupa area, Mozambique. Magnetic separation removed the majority of iron and titanium, whereas H2SO4 leaching removed a large portion of thorium and uranium in these samples. Analytical results indicated that 64.14wt% and 72.04wt% of the total Fe and Ti, respectively, and ∼2wt% each of Nb2O5 and Ta2O5 were removed from sample C (ferrotantalite) using the magnetic separation method, whereas only 9.64wt% and 8.66wt% of total Fe2O3 and TiO2, respectively, and ∼2wt% each of Nb2O5 and Ta2O5 were removed from sample A (manganotantalite). A temperature of 50°C and a leaching time of 3 h in the presence of concentrated H2SO4 were observed to be the most appropriate leaching conditions for removal of radioactive elements from the tantalite ores. The results obtained for sample A under these conditions indicated that 64.14wt% U3O8 and 60.77wt% ThO2 were leached into the acidic solution, along with 4.45wt% and 0.99wt% of Nb2O5 and Ta2O5, respectively.

Analysis of Non-Conducting Tantalite Minerals by Glow Discharge Optical Emission Spectrometry

Capabilities of the radio frequency glow discharge optical emission spectroscopy (RF-GD-OES) for analysis of Ta2O5/Nb2O5 and tantalum and niobium in electrically non-conducting geological samples were investigated. The metal pentoxides (Ta2O5 and Nb2O5) and the tantalite mineral powders were mixed with a thermally conductive copper powder in ratios of up to 1:10 sample:copper and pressed into a disc sample for glow discharge sputtering. Studies were carried out to determine and optimize all the parameters affecting the analyses by the RF-GD-OES technique. This included the determination of the ability of the methodology to generate usable analytical curves for the target elements. Good calibration curves which were used for analyses of Ta and Nb in the tantalite minerals were obtained at optimized experimental conditions. Respective tantalum and niobium recoveries were in the order of 99.78–104.91% and 98.34–102.03% from the mineral analyses.