Preparation of industrial ammonium metatungstate ( <scp>AMT</scp> ) from sulphuric‐cum‐phosphoric acid leaching by solvent extraction with aliquat‐336

Abstract

Abstract In this study, the acid dissolution and subsequent solvent extraction of a Nigerian wolframite ore was examined. The combinations of sulphuric‐cum‐phosphoric acid solutions were used as the leachants. The effect of process parameters such as reaction temperature, concentration, and particle size were investigated. At optimal leaching conditions (2.0 M H 2 SO 4 + 0.15 M H 3 PO 4 , 75°C, −90 + 75 μm), 93.7% of the ore reacted within 120 min. The Avrami model was proposed and considered based on the experimental data obtained in this study. The derived activation energy of 12.32 kJ/mol from the study indicates the reaction to be of an internal diffusion reaction model with minimal eco‐feasible energy. Suggesting that the process is energy saving and eco‐friendly. The extraction process by aliquat‐336 yielded 95% of pure tungsten at 27 ± 2°C. The optimization of pure tungsten solution through crystallization process gave high‐grade AMT of the form (NH 4 ) 6 [H 2 W 12 O 40 ] · 4H 2 O: 96‐901‐3322, melting point 101.4°C is therefore recommended for industrial applications in catalytic operations.