Purification and particulate controllable of tungsten particles by hydrometallurgy combined with spray drying-pyrolysis process

Abstract:

Tungsten is widely used as semiconductor and high-temperature materials. In this study, high-purity well-dispersed micro-spherical W particles were synthesized from commercial ammonium paratungstate [(NH₄)₁₀[H₂W₁₂O₄₂].nH₂O] sequential by ion exchange, extraction, re-crystallization, spraying dry and pyrolysis processes. Impurities in the starting ammonium paratungstate were eliminated by the hydrometallurgy treatments. The morphology and size of as-synthesized W particles were controlled by the spraying dry-pyrolysis treatments. The influences of solution concentration in spraying dry on the morphology of (NH₄)₁₀[H₂W₁₂O₄₂] particles were investigated. The pyrolysed mechanism of as-spraying dried (NH₄)₁₀[H₂W₁₂O₄₂] particles transformed to as-synthesized W particles was revealed. The purity of as-fabricated tungsten powder is higher than 99.995 wt%, and the average size is about 1.5 μm. It should be noted that the hydrometallurgy and powder technology in this study can be applied to synthesize other metal particles with high-performance requirements.

Key words:high-purity; well-dispersed; micro-spherical; solution concentration; pyrolysed mechanism