Production of anhydrous hydrogen fluoride from low-grade metallic fluorides and sulfuric acid
AssigneeFlorida Progress Corporation
InventorsWilliam W. Berry, Robert A. Ashworth, Ned B. Spake
Life of this patent
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Abstract
A novel method is provided for the production of anhydrous hydrofluoric acid from low-grade metallic fluorides using an intermediate aluminum fluoride compound. The method involves the reaction of low-grade metallic fluorides such as fluorspar with sulfuric acid to produce weak hydrofluoric acid. The weak acid is then reacted with a metallic salt (such as aluminum chloride) to form precipitated aluminum fluoride (AlF.sub.3.3H.sub.2 O). After dewatering, the aluminum fluoride is reacted with strong sulfuric acid to form aluminum sulfate and strong hydrofluoric acid.
Claims13
A process for the production of anhydrous hydrofluoric acid from low-grade sources of fluorine comprising:
- (a) reacting a low grade source of fluorine comprised of a metallic fluoride with sulfuric acid in a reaction zone at a temperature ranging from about 140.degree. to 220.degree. C. to produce hydrogen fluoride and hydrated metallic sulfate;
- (b) recovering said hydrogen fluoride formed in step (a);
- (c) reacting said recovered hydrogen fluoride with a metallic salt of a metal in the form of an aqueous solution thereof which metal forms slightly soluble or insoluble fluorides at a temperature ranging from about ambient to about 120.degree. C. to produce a hydrated metallic fluoride and a corresponding acid;
- (d) recovering said hydrated metallic fluoride from step (c) as a precipitate and heating said metallic fluoride to a temperature sufficient to remove bound water;
- (e) reacting said dehydrated metallic fluoride from step (d) with sulfuric acid at a temperature ranging from about 70.degree. to about 120.degree. C. to produce anhydrous hydrofluoric acid and a metallic sulfate;
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- (f) recovering said anhydrous hydrofluoric acid.
Dependencies are inferred from the claim text.