
Grade 1 tungsten trioxide is referred to as a light yellow crystalline powder with grade of WO3-1. Processes of Double Salt Method to Produce Tungsten Trioxide 1. By using sodium hydroxide to decompose tungsten concentrate to obtain crude sodium tungstate solution. 2. By adopting an improved “Chemical Purification Method” to remove silicon (Si), phosphorus (P), arsenic (As), fluorine (F), molybdenum (Mo) and other major impurities in the obtained solution. 3. Ammonium chloride is added to form “ammonium paratungstate – sodium…