Production of pure tantalum and niobium oxides by hydrometallurgical processing of coltan smelter cake from Tanganyika Province/RD Congo using NH4HF2-KOH flux system.
 
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1. Department of Chemistry, Faculty of Sciences, University of Lubumbashi, Haut-Katanga, DR Congo.
 
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2. Faculty of Sciences, Molecular Science Institute, African Research University Alliance-Center of Excellence-Materials for Energy and Nanotechnology, University of Witwatersrand, Johannesburg, RSA.
 
 
Publication date: 2024-08-22
 
 
Corresponding author
Bertin Kitungwa Kabuge   

1. Department of Chemistry, Faculty of Sciences, University of Lubumbashi, Haut-Katanga, DR Congo.
 
 
Physicochem. Probl. Miner. Process. 2024;60(4):192436
 
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ABSTRACT
Pure tantalum and niobium oxides were produced from the molten cake after mixing ore-NH4HF2-KOH in a respective mass ratio of 1/4/3. This resulted in solubilization yields of over 95% for Nb and around 92% for Ta in sulfuric acid solution 3 molar. Extraction of tantalum and niobium using octan-2-ol yielded over 95% niobium and 98% tantalum when pH is set at 0.5-1.0 and 1.5-2 respectively. The compounds K3NbOF6, K3NbO4 and K2TaF7 were identified after melting. While in aqueous solution ionic species such as NbF6(OH)23-, NbF6- and TaF72- are likely to be identified. Precipitation of tantalum and niobium in NH4OH solution (pH=7.50-8.0) as hydrated oxides after stripping with distilled water and crystallization by evaporation identified hydrated oxides such as Ta2O5.nH2O, Nb2O5.nH2O. These two oxides were associated with a small amount of SiO2.nH2O as an impurity resulting from the extraction and precipitation of tantalum and niobium. SEM-EDS, XRD, TGA-DTG and FTIR analyses identified and characterized these compounds.
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ISSN:1643-1049
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