Interaction of Tungsten-Containing Mineral Raw Materials with a Mixture of Ammonium Bifluoride and Sulfate

Abstract The interaction of tungsten mineral raw materials with a mixture of NH4HF2 and (NH4)2SO4 upon heating was studied. It was determined that, first, at temperatures up to 200°C, the incoming components are fluorinated to form complex and simple fluorides. A further increase in temperature is accompanied by the decomposition of ammonium sulfate to form NH4HSO4, which leads to the conversion of fluorides into sulfates and of the tungsten ammonium fluoride complex into tungstic acid H2WO4. It was shown that water leaching of the product of the decomposition of tungsten-containing mineral raw materials with a mixture of NH4HF2 and (NH4)2SO4 makes it possible to extract tungsten from mineral raw materials in the form of the commercial product WO3.