Ammonium para-tungstate production in good yield without neutralising excess soda and acidification

摘要

Production of ammonium para-tungstate (I) comprises autoclave lixiviation of a material with an alkaline solution, enrichment of tungsten (W) and purification by extraction of W directly from the solution using anion exchanger. Both the liquid and solid anion exchanger molecules constantly contain organic cations during contact with the alkaline medium.