METHOD FOR PRODUCING UHP TUNGSTEN HEXAFLUORIDE

摘要

PROBLEM TO BE SOLVED: To obtain UHP(ultra-high-purity) tungsten hexafluoride through such steps that tungsten hexafluoride containing volatile impurities is separated from crude tungsten hexafluoride, a semi-crude tungsten hexafluoride product is then separated from the tungsten hexafluoride containing volatile impurities, and a nonvolatile UHP tungsten hexafluoride is subsequently separated from the above product. SOLUTION: This UHP tungsten hexafluoride is obtained by the following steps: crude tungsten hexafluoride is introduced into an evaporation process where it is separated into tungsten hexafluoride containing volatile impurities and nonvolatile metallic impurities; the tungsten hexafluoride containing volatile impurities is then passed through a vapor phase adsorption process where it is separated into a semi-crude tungsten hexafluoride product and hydrogen fluoride nonvolatile residues by the aid of an NaF or KF reactive adsorption bed; the semi-crude tungsten hexafluoride product is subsequently passed through a sparging system using UHP helium to separate the objective nonvolatile UHP tungsten hexafluoride product.