Process for the production of phosphoric acid and hydrogen fluoride from phosphate rock and fluosilicic acid
AssigneePhosphate Engineering & Construction Co., Inc.
InventorsWilliam R. Erickson, Leif E. Bouffard
Life of this patent
Estimating the term…
Abstract
Fluosilicic acid is reacted with phosphate rock in order to produce wet process phosphoric acid and calcium fluoride which is later reacted with sulfuric acid to produce hydrogen fluoride and calcium sulfate. The hydrogen fluoride is then stripped from the phosphoric acid and recovered as either anhydrous hydrogen fluoride or concentrated hydrofluoric acid or reacted aluminum trihydrate to produce aluminum fluoride; with sodium carbonate to produce sodium fluoride/bifluoride; or with ammonia to produce ammonium fluoride/bifluoride.
Claims33
A process for the production of phosphoric acid and hydrogen fluoride from a feedstock of phosphate rock and fluosilicic acid (FSA) comprising the steps of:
- A. reacting the phosphate rock and FSA together to produce a reaction slurry of phosphoric acid, calcium fluoride, silicon dioxide, and undigested phosphate rock;
- B. separating the phosphoric acid and calcium fluoride from the undigested phosphate rock and silicon dioxide;
- C. mixing the phosphoric acid and calcium fluoride with a sufficient amount of sulfuric acid to convert the calcium fluoride to hydrogen fluoride and calcium sulfate;
- and
- D. recovering the hydrogen fluoride as a concentrated hydrogen fluoride solution or as anhydrous hydrogen fluoride.
A process for the production of hydrogen fluoride and phosphoric acid from a feedstock of phosphate rock and fluosilicic acid (FSA) comprising the steps of:
- A. reacting an excess stoichiometric amount of calcium, as the tricalcium phosphate and calcium carbonate fraction of the rock, to fluorine in the fluosilicic acid to produce a reaction slurry of phosphoric acid, calcium fluoride, silicon dioxide, and undigested phosphate rock;
- B. separating a phosphoric acid/calcium fluoride slurry from the undigested phosphate rock and silicon dioxide;
- C. mixing the phosphoric acid and calcium fluoride slurry with a sufficient amount of sulfuric acid to convert calcium fluoride to hydrogen fluoride and calcium sulfate;
- and
- D. recovering the hydrogen fluoride as a concentrated hydrogen fluoride solution or as anhydrous hydrogen fluoride.
A process for the production of hydrogen fluoride from a feedstock of phosphate rock and fluosilicic acid (FSA) comprising the steps of:
- A. reacting an excess stoichiometric amount of calcium, as the tricalcium phosphate and calcium carbonate fraction of the rock, to fluorine in the fluosilicic acid to produce a reaction slurry of phosphoric acid, calcium fluoride, silicon dioxide, and undigested phosphate rock;
- B. separating the phosphoric acid and calcium fluoride from the undigested phosphate rock and silicon dioxide;
- C. mixing the phosphoric acid and calcium fluoride with a sufficient amount of sulfuric acid to convert calcium fluoride to hydrogen fluoride and calcium sulfate;
- and
- D. stripping the hydrogen fluoride from the phosphoric acid as a hydrogen fluoride vapor;
- E. contacting the hydrogen fluoride vapors with a scrubbing solution selected from the group consisting of solutions of alumina trihydrate, sodium aluminate, aluminum sulfate, sodium hydroxide, sodium carbonate, and ammonia to form precipitated salts;
- and
- F. thereafter separating precipitated salts and recirculating the scrubbing solution.
Dependencies are inferred from the claim text.