Method for preparing ultra-pure zirconium and hafnium tetrafluorides
AssigneeHughes Aircraft Company
InventorsRicardo C. Pastor, Morton Robinson
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Abstract
A method for preparing ultra-pure metal tetrafluorides in which 3d such as Fe impurities are separated from impure material by a combined vaporization-electrolytic separation procedure. Sublimation and distillation methods are disclosed in combination with electrolytic separation by both emf-series displacement (ESD) and direct melt electrolysis (DME).
Claims17
In a method for separating iron impurities from an impure metal halide in which the impure metal halide is heated to a temperature sufficient to form a metal halide vapor, said vapor being separated from said impure metal halide and condensed to form purified metal halide having a reduced iron content, wherein the improvement comprises:
- utilizing electromotive series displacement by contacting a melt containig the impure metal halide with a pure metal, said electromotive series displacement causing the plating out of 3d metal impurities.
In a method for separating iron impurities from an impure metal halide in which the impure metal halide is heated to a temperature sufficient to form a metal halide vapor, said vapor being separated from said impure metal halide and condensed to form a purified metal halide having a reduced iron content, wherein the improvement comprises:
- applying an electromotive force to said impure metal halide during the vaporization of said impure metal halide, said electromotive force being sufficient to convert relatively volatile transition metal 3d impurities in said impure metal halide to relatively non-volatile 3d metal impurities, wherein said non-volatile 3d metal impurities remain in said impure metal halide during said separation and are not vaporized and condensed with said purified metal halide.
Dependencies are inferred from the claim text.