WaterSolutions Separation of Tungsten from Liquid Media

Mining: Ion exchange resins are employed in the commercial mining and refining of tungsten. Both, strong base and weak base anion exchange resins are employed for removal from strongly acidic feed streams. Nevertheless, the weakly basic anion exchanger, DOWEX™ M-43 resin is preferred for its high capacity and cleaner elution characteristics. Elution is usually accomplished using 10% sodium hydroxide.

Wastewater/ Groundwater: In waters with low levels of W (VI), strongly acidic cation exchange resins such as DOWEX G-26 (H) cation exchange resin are employed. Weak acid cation exchange resins such as DOWEX MAC-3 resins often provide high capacity and good multi-valent ion selectivity. However, in more brackish waters, chelating resins may be required. Chelating resins have reactive units dispersed along their polymer matrix, each of which have multiple metal binding sites. Hence, chelating resins are selective for multi-valent cations, over mono-valent cations such as sodium and potassium.