US4176022A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Removal of part per billion level hardness impurities from alkali metal chloride brines
Assignee: PPG Industries Inc
•
Filing: 1978-04-27
•
Granted: 1979-11-27
•
Expires: 1998-04-27
Abstract
Abstract Disclosed is a method of electrolyzing an alkali metal chloride brine in an electrolytic cell by feeding an aqueous alkali metal chloride brine containing less than 20 parts per billion dissolved alkaline earth metal ions, e.g., calcium, to the anolyte compartment of an electrolytic cell. Also disclosed is an alkali metal chloride brine containing less than 20 parts per billion of alkaline earth metal ions, e.g., calcium ion. There is also disclosed a method of purifying alkaline earth metal-containing brines, e.g., calcium-containing brines, by maintaining the brine alkaline, adding a phosphate to the alkaline brine whereby to form a calcium compound substantially insoluble in brine and thereafter separating the compound from the brine.
Inventors
- 👤 William B. Darlington
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 06:42
CPC Classifications
C; C25; C25B; C25B1/00; C25B1/01; C25B1/34; C25B1/46; C01; C01D; C01D3/00; C01D3/14; C01D3/145; C01D3/16; C25B15/00; C25B15/08; C25B15/085
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
133 words
A method of electrolyzing an alkali metal chloride brine in an electrolytic cell having an anolyte compartment separated from a catholyte compartment by a semi-permeable barrier which method comprises: maintaining a calcium ion containing brine alkaline; adding a phosphate chosen from the group consisting of phosphoric acid, sodium orthophosphate, sodium metaphosphate, sodium polyphosphate, potassium orthophosphate, potassium metaphosphate, potassium polyphosphate, and mixtures thereof to said alkaline brine whereby to form an insoluble precipitate having the stoichiomatic formula (CaX 2 ) . (Ca(PO 4 ) 2 ) 3 wherein X is chosen from the group consisting of F, Cl and OH; separating the precipitate from the brine; feeding the brine, containing less than 20 parts per billion of calcium ion, to the anolyte compartment of the cell; and passing an electrical current through the cell.
Claim 2
Independent Claim
133 words
A method of electrolyzing an alkali metal chloride brine in an electrolytic cell having an anolyte compartment separated from a catholyte compartment by a semi-permeable barrier which method comprises: maintaining a calcium ion containing brine alkaline; adding a phosphate chosen from the group consisting of phosphoric acid, sodium orthophosphate, sodium metaphosphate, sodium polyphosphate, potassium orthophosphate, potassium metaphosphate, potassium polyphosphate, and mixtures thereof to said alkaline brine whereby to form an insoluble precipitate having the stoichiomatic formula (CaX 2 ) . (Ca(PO 4 ) 2 ) 3 wherein X is chosen from the group consisting of F, Cl and OH; separating the precipitate from the brine; feeding the brine, containing less than 20 parts per billion of calcium ion, to the anolyte compartment of the cell; and passing an electrical current through the cell.
Claim 3
Dependent Claim
13 words
The method of claim 1 comprising adding seeding agent to said alkaline brine.
Claim 4
Dependent Claim
25 words
The method of claim 2 wherein the seeding agent is chosen from the group consisting of calcium phosphate, calcium fluoro-apatite, calcium hydroxy-apatite, and calcium hydroxide.
Claim 5
Dependent Claim
19 words
The method of claim 1 comprising passing the brine through filtering media and recovering a substantially calcium-free brine therefrom.
Claim 6
Dependent Claim
21 words
The method of claim 4 wherein said filtering media has a pore size of from about 0.4 to about 1 micron.
Claim 7
Dependent Claim
22 words
The method of claim 1 wherein the brine is adjusted to a pH of about 10 prior to addition of the phosphate.
Claim 8
Dependent Claim
24 words
The method of claim 1 wherein the phosphate is chosen from the group consisting of phosphoric acid, sodium phosphate, potassium phosphate, and mixtures thereof.
Claim 9
Dependent Claim
20 words
The method of claim 1 comprising adding an alkali metal fluoride to said alkaline brine whereby to form a fluoro-apatite.
Claim 10
Independent Claim
92 words
A method of electrolyzing an alkali metal chloride brine containing alkaline earth metal ions as an impurity in an electrolytic cell having an anolyte compartment separated from a catholyte compartment by a semi-permeable barrier which method comprises: maintaining the brine alkaline; adding a phosphate and a fluoride to said alkaline brine whereby to form a precipitate; separating the precipitate from the brine; feeding the brine, containing less than 20 parts per billion of alkali earth metal ion, to the anolyte compartment of the cell; and passing an electrical current through the cell.
Claim 11
Independent Claim
92 words
A method of electrolyzing an alkali metal chloride brine containing alkaline earth metal ions as an impurity in an electrolytic cell having an anolyte compartment separated from a catholyte compartment by a semi-permeable barrier which method comprises: maintaining the brine alkaline; adding a phosphate and a fluoride to said alkaline brine whereby to form a precipitate; separating the precipitate from the brine; feeding the brine, containing less than 20 parts per billion of alkali earth metal ion, to the anolyte compartment of the cell; and passing an electrical current through the cell.
Claim 12
Dependent Claim
13 words
The method of claim 9 comprising adding seeding agent to said alkaline brine.
Claim 13
Dependent Claim
25 words
The method of claim 10 wherein the seeding agent is chosen from the group consisting of calcium phosphate, calcium fluoro-apatite, calcium hydroxy-apatite, and calcium hydroxide.
Claim 14
Dependent Claim
20 words
The method of claim 9 comprising passing the brine through filtering media and recovering a substantially alkaline earth-free brine therefrom.
Claim 15
Dependent Claim
21 words
The method of claim 12 wherein said filtering media has a pore size of from about 0.4 to about 1 micron.
Claim 16
Dependent Claim
22 words
The method of claim 9 wherein the brine is adjusted to a pH of about 10 prior to addition of the phosphate.
Claim 17
Dependent Claim
24 words
The method of claim 9 wherein the phosphate is chosen from the group consisting of phosphoric acid, sodium phosphate, potassium phosphate, and mixtures thereof.
Claim 18
Dependent Claim
13 words
The method of claim 9 wherein the fluoride is an alkali metal fluoride.
Claim 19
Independent Claim
108 words
A method of purifying alkali metal chloride brine having an alkali metal chloride content of 225 to 325 grams per liter and containing 200 to 500 parts per billion of calcium ion comprising: maintaining the brine alkaline; adding a phosphate chosen from the group consisting of phosphoric acid, sodium orthophosphate, sodium metaphosphate, sodium polyphosphate, potassium orthophosphate, potassium metaphosphate, potassium polyphosphate, and mixtures thereof to said alkaline brine whereby to form an insoluble precipitate having the stoichiometric formula (CaX 2 ) . (Ca(PO 4 ) 2 ) 3 wherein X is chosen from the group consisting of F, Cl, and OH; and separating the insoluble precipitate from the brine.
Claim 20
Independent Claim
108 words
A method of purifying alkali metal chloride brine having an alkali metal chloride content of 225 to 325 grams per liter and containing 200 to 500 parts per billion of calcium ion comprising: maintaining the brine alkaline; adding a phosphate chosen from the group consisting of phosphoric acid, sodium orthophosphate, sodium metaphosphate, sodium polyphosphate, potassium orthophosphate, potassium metaphosphate, potassium polyphosphate, and mixtures thereof to said alkaline brine whereby to form an insoluble precipitate having the stoichiometric formula (CaX 2 ) . (Ca(PO 4 ) 2 ) 3 wherein X is chosen from the group consisting of F, Cl, and OH; and separating the insoluble precipitate from the brine.
Claim 21
Dependent Claim
13 words
The method of claim 17 comprising adding seeding agent to said alkaline brine.
Claim 22
Dependent Claim
25 words
The method of claim 18 wherein the seeding agent is chosen from the group consisting of calcium phosphate, calcium fluoro-apatite, calcium hydroxy-apatite, and calcium hydroxide.
Claim 23
Dependent Claim
19 words
The method of claim 17 comprising passing the brine through filtering media and recovering a substantially calcium-free brine therefrom.
Claim 24
Dependent Claim
21 words
The method of claim 20 wherein said filtering media has a pore size of from about 0.4 to about 1 micron.
Claim 25
Dependent Claim
22 words
The method of claim 17 wherein the brine is adjusted to a pH of about 10 prior to addition of the phosphate.
Claim 26
Dependent Claim
24 words
The method of claim 17 wherein the phosphate is chosen from the group consisting of phosphoric acid, sodium phosphate, potassium phosphate, and mixtures thereof.
Claim 27
Dependent Claim
21 words
The method of claim 17 comprising adding an alkali metal fluoride to said alkaline brine whereby to form an insoluble precipitate.
Claim 28
Dependent Claim
22 words
The method of claim 17 comprising recovering an alkali metal chloride brine containing less than 20 parts per billion of calcium ion.
Claim 29
Independent Claim
46 words
A method of purifying alkali metal chloride brine containing 200 to 500 parts per billion of alkaline earth metal ion comprising: maintaining the brine alkaline; adding a phosphate and fluoride to said alkaline brine whereby to form a precipitate; and separating the precipitate from the brine.
Claim 30
Independent Claim
46 words
A method of purifying alkali metal chloride brine containing 200 to 500 parts per billion of alkaline earth metal ion comprising: maintaining the brine alkaline; adding a phosphate and fluoride to said alkaline brine whereby to form a precipitate; and separating the precipitate from the brine.
Claim 31
Dependent Claim
13 words
The method of claim 26 comprising adding seeding agent to said alkaline brine.
Claim 32
Dependent Claim
25 words
The method of claim 27 wherein the seeding agent is chosen from the group consisting of calcium phosphate, calcium fluoro-apatite, calcium hydroxy-apatite, and calcium hydroxide.
Claim 33
Dependent Claim
25 words
The method of claim 26 wherein the alkali metal chloride brine contains from about 225 to about 325 grams per liter of alkali metal chloride.
Claim 34
Dependent Claim
22 words
The method of claim 26 wherein the brine is adjusted to a pH of about 10 prior to addition of the phosphate.
Claim 35
Dependent Claim
24 words
The method of claim 26 wherein the phosphate is chosen from the group consisting of phosphoric acid, sodium phosphate, potassium phosphate, and mixtures thereof.
Claim 36
Dependent Claim
13 words
The method of claim 26 wherein the fluoride is an alkali metal fluoride.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-11-26 | 1983-05-28 | 1983-11-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-11-26 | 1987-05-28 | 1987-11-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-11-26 | 1991-05-28 | 1991-11-27 | $7700.00 | Window Closed / Lapsed |