Recovery of tungsten from downstream mineral processing fractions by Deep Eutectic Solvents

Tungsten is a scarce and valuable metal with a wide range of applications. Currently, the recovery of tungsten from scheelite concentrates involves the use of strong acids, alkalis, and/or high temperatures (roasting). Deep Eutectic Solvents (DES) are proposed as an environmentally friendly alternative for the leaching process aiming to extract the tungsten contained. In this work, high grade scheelite concentrate (W 57%) was the material used for the investigation. After an exhaustive DES screening, choline chloride-oxalic acid (ChCl/OA)-based DES showed the best leaching performance. An optimization of the leaching variables (temperature, time, liquid/solid ratio, ChCl/OA ratio) was carried out. A W extraction yield as high as 95% was achieved at certain operating conditions.