US3390064A - Electrolytic process for preparing stannous fluoride - Google Patents
Electrolytic process for preparing stannous fluoride Download PDFInfo
- Publication number
- US3390064A US3390064A US401926A US40192664A US3390064A US 3390064 A US3390064 A US 3390064A US 401926 A US401926 A US 401926A US 40192664 A US40192664 A US 40192664A US 3390064 A US3390064 A US 3390064A
- Authority
- US
- United States
- Prior art keywords
- tin
- mercury
- anode
- stannous fluoride
- cell
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- ANOBYBYXJXCGBS-UHFFFAOYSA-L stannous fluoride Chemical compound F[Sn]F ANOBYBYXJXCGBS-UHFFFAOYSA-L 0.000 title claims description 34
- 229960002799 stannous fluoride Drugs 0.000 title claims description 34
- 238000004519 manufacturing process Methods 0.000 title claims description 10
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 32
- 229910000497 Amalgam Inorganic materials 0.000 claims description 15
- YUOWTJMRMWQJDA-UHFFFAOYSA-J tin(iv) fluoride Chemical compound [F-].[F-].[F-].[F-].[Sn+4] YUOWTJMRMWQJDA-UHFFFAOYSA-J 0.000 claims description 9
- DAEJUPKPHRBQHZ-UHFFFAOYSA-N [Sn].[Hg] Chemical compound [Sn].[Hg] DAEJUPKPHRBQHZ-UHFFFAOYSA-N 0.000 claims description 7
- 238000011109 contamination Methods 0.000 claims description 6
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 42
- 239000000243 solution Substances 0.000 description 34
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 27
- 229910052753 mercury Inorganic materials 0.000 description 25
- -1 mercuric nitrate Chemical compound 0.000 description 11
- 239000004698 Polyethylene Substances 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- 229920000573 polyethylene Polymers 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 6
- 238000000576 coating method Methods 0.000 description 6
- 239000003792 electrolyte Substances 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 238000005868 electrolysis reaction Methods 0.000 description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
- 238000007598 dipping method Methods 0.000 description 3
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- 239000004793 Polystyrene Substances 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 230000008025 crystallization Effects 0.000 description 2
- ORMNPSYMZOGSSV-UHFFFAOYSA-N dinitrooxymercury Chemical compound [Hg+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ORMNPSYMZOGSSV-UHFFFAOYSA-N 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 229910000040 hydrogen fluoride Inorganic materials 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 229920003023 plastic Polymers 0.000 description 2
- 239000004033 plastic Substances 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 229920002223 polystyrene Polymers 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- XOLBLPGZBRYERU-UHFFFAOYSA-N tin dioxide Chemical compound O=[Sn]=O XOLBLPGZBRYERU-UHFFFAOYSA-N 0.000 description 2
- 229920011532 unplasticized polyvinyl chloride Polymers 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000012935 Averaging Methods 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 241000282320 Panthera leo Species 0.000 description 1
- GPQUEUOSGZMUQE-UHFFFAOYSA-N [O-2].[Hg+].[Hg+] Chemical compound [O-2].[Hg+].[Hg+] GPQUEUOSGZMUQE-UHFFFAOYSA-N 0.000 description 1
- 238000013019 agitation Methods 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000011437 continuous method Methods 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 238000010348 incorporation Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 150000002730 mercury Chemical class 0.000 description 1
- RPZHFKHTXCZXQV-UHFFFAOYSA-N mercury(I) oxide Inorganic materials O1[Hg][Hg]1 RPZHFKHTXCZXQV-UHFFFAOYSA-N 0.000 description 1
- 229940008718 metallic mercury Drugs 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- CJGYQECZUAUFSN-UHFFFAOYSA-N oxygen(2-);tin(2+) Chemical compound [O-2].[Sn+2] CJGYQECZUAUFSN-UHFFFAOYSA-N 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 230000002028 premature Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- 229910001432 tin ion Inorganic materials 0.000 description 1
- QHGNHLZPVBIIPX-UHFFFAOYSA-N tin(II) oxide Inorganic materials [Sn]=O QHGNHLZPVBIIPX-UHFFFAOYSA-N 0.000 description 1
- 239000000606 toothpaste Substances 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Images
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G19/00—Compounds of tin
- C01G19/04—Halides
Definitions
- Stannous fluoride is an article of commerce with well established uses, one of which is its incorporation into fluoride-containing tooth pastes. For such purposes the stannous fluoride must meet rigid purity specifications and must be free from substantial contamination with stannic fluoride. Stannic tin contents of less than 3% are often specified.
- Stannous fluoride has been produced in the past from stannic oxide by dissolving the oxide in hydrofluoric acid and recovering the resulting stannous fluoride. This is an expensive process, since stannous oxide is produced from metallic tin. If a satisfactory process could be devised for using tin metal to produce stannous fluoride, considerable savings could be effected.
- prior attempts to utilize metallic tin have left something to be desired.
- Another object of the invention is to provide a process for the electrolytic production of stannous fluoride wherein an exceptionally pure product is produced.
- a further object of the invention is to provide a process for preparing stannous fluoride from metallic tin and hydrofluoric acid solution.
- a still further object of the invention is to provide a process for the continuous production of stannous fluoride by the electrolysis of aqueous hydrofluoric acid solutions between a mercury cathode and a tin anode.
- the tin dissolves from the amalgam, free of any insoluble slime.
- the mercury of the amalgam does not dissolve, but simply serves as a transfer point for the tin about to go into solution. A small amount of mercury will etfectively coat a tin pig or sheet, the percentage of mercury increasing progressively until the anode is completely consumed.
- the mercury is applied to the tin anode either by dipping the tin directly into metallic mercury or by applying a solution of a mercury salt to the tin such as mercuric nitrate, whereupon reduction to mercury occurs. A single dipping with a few minutes soaking will reduce enough mercury to give effective coating. After dipping, the anode is washed off with water to remove any excess salt.
- a mercury salt such as mercuric nitrate
- amalgam coating When using elemental mercury to form the amalgam, a coating of one gram of mercury per square foot (0.09 sq. m.) is adequate although not critical. In general, an amalgam coating as thin as about 0.2 micron is satisfactory.
- any suitable electrolytic cell preferably a cell such as is disclosed and claimed in our copending application Ser. No. 265,211, filed Mar. 14, 1963, and now Patent No. 3,300,397, and shown in the annexed drawing.
- the attached drawing is a schematic representation of apparatus suitable for carrying out continuous electrolytic production of stannous fluoride in accordance with a preferred modification of the present invention.
- a main electrolytic cell 1 The cell may be fabricated from iron or other suitable material.
- the cell When the cell is made of a material which conducts electricity and/ or is subject to corrosion by the contents of the cell, it may be provided with a plastic lining composed, for example, of polyethylene, polypropylene, polystyrene, unplasticized polyvinyl chloride, etc.
- Cell 1 having a suitable support 2 is provided with a cathode 3, comprising a container 4, having a pool of mercury 5, and cathode lead 6, immersed in the mercury.
- the cathode lead must have good conduction and may be any metal which does not amalgamate to substantial extent, e.g., iron.
- the bottom 4a of the cathode container is a porous, woven material which is inert to hydrofluoric acid solution but offers low resistance to the electrolytic reaction.
- the material is composed preferably of linear polyethylene.
- the sides of the cathode container are relatively rigid and are made preferably of non-porous plastic material which is inert to the acid solution. Typical materials include polyethylene, polystyrene, polypropylene, polytetrafluoroethylene, metals coated with unplasticized polyvinyl chloride, etc.
- An anode 7, composed of tin in stick, sheet or other suitable form, covered with a thin film of mercury-tin amalgam 7a, is disposed near the bottom of cell 1 and is provided with anode lead 8.
- the anode lead can be a threaded carbon rod screwed into a carbon slab 8a at the bottom of the cell.
- the anode lead can be com osed of any suitable metal provided with acid-resistant insulation, e.g., polyethylene.
- hydrofluoric acid solution is introduced through line 9 to form the electrolyte in cell 1.
- the electrolyte entering the cell may be heated, and/or external heat may be applied to the cell to attain the desired temperature, i.e., about 40 C. to 60 C.
- tin ions from the anode react with the hydrofluoric acid solution to produce stannous fluoride solution at the anode: surface.
- Hydrogen is evolved at the cathode.
- the stannous fluoride solution increases in strength, the gravity difference between it and the hydrofluoric acid solution results in formation of a layer 11 of the stannous fluoride solution at the lower part of the cell.
- the hydrofluoric acid solution forms a layer 12 above the stannous fluoride solution.
- the concentrated stannous fluoride solution is withdrawn through line 13 by means of pump 14, while hydrofluoric acid solution is added to the cathode container via line 9.
- the stannous fluoride solution is collected in receiver 15.
- the aqueous stannous fluoride solution withdrawn from the cell can be isolated and recovered by any desired means, for example, by concentration of the solution followed by cooling to effect crystallization.
- the resulting recovered stannous fluoride product has a stannic tin content less than about 1%, usually of about 0.3%0.6% based on 100% stannous fluoride, whereas under the same conditions, using a tin anode without the amalgam coating stannic contents in excess of about occur, often as high as 9% or higher.
- the mercury of the cathode can be purified by continuously withdrawing it from cathode container 4 via line 16, and permitting it to flow into a small auxiliary electrolytic cell 17, fabricated from the same material used for cell 1, where the pool of mercury becomes an anode 18.
- the mercury has anode lead 19 immersed in it.
- Cell 17 is also provided with cathode plate 21, which is preferably carbon but may also be composed of any suitable metal such as tin. Plate 21 is provided with cathode lead 22.
- the cell contains a suitable electrolyte 20, e.g. hydrofluoric acid solution. Agitation in the cell is provided by means of agitator 23, to prevent mercurous oxide formation.
- tin from the mercury is plated out .on cathode plate 21.
- the amount of tin removed from the cathode mercury can be varied by changing the current on the power source, and the temperature of the cathode mercury can be controlled by changing the pumping rate.
- Purified mercury is con- .tinuously sent via line 24 by means of pump 25 into washing tower 26, in which cold water is continuously introduced through line 27 and withdrawn through line 28. The cooled purified mercury is returned via line 29 to cathode container 4 of the main electrolytic cell.
- Hydrofluoric acid solution concentration should be at least about 5%, preferably not more than about 20%, suitably between about 9% and 15%. At lower HF concentrations, greater quantities of SnF are soluble in the solution than at higher concentrations.
- the concentration :of SnF which is withdrawn from the cell can be any desired strength up to the saturation point in the particular HF solution employed. Higher concentrations are more productive and simplify the subsequent recovery of SnF in the solid state and hence are preferred. However, withdrawal of SnF solution before it reaches the saturation point is desirable in order to prevent premature crystalliz-ation. In general, operating at between about 9% and about 15% concentrations, at cell temperatures between about 50 C. and about 60 C., concentrations of SnF removed will preferably range between about 20% and about 40%.
- Current densities are not unduly critical and may suitably be in the range between about 100 and about 300 amps/sq. foot at the cathode and between about 20 and about 60 amps/sq. foot at the anode.
- EXAMPLE 1 A reactor of the character shown in the drawing, having a polyethylene lining, was charged with a tin anode which had been treated with mercury by immersing it in liquid mercury, to give a coating of mercury-tin amalgam on its surface.
- the cell was filled with a aqueous solution of hydrofluoric acid, to a depth of 6 inches (about 3 gallons).
- a mercury cathode in a polyethylene cup with a polyethylene cloth bottom was fixed about 2.5 inches above the top of the tin anode.
- Current was turned on and maintained at.30 amps at an average of 5 volts after the solution had warmed up to about 50 C.
- the current density on the cathode was 158 amps/sq. ft. and on the anode was 29 amps/sq. ft.
- Stannous fluoride was thus produced and dissolved in the hydrogen fluoride.
- a method for producing stannous fluoride free from substantial contamination with stannic fluoride which comprises passing an electric current between 'a mercury cathode and an anode of metallic tin having superimposed thereon a thin layer of mercury-tin amalgam, said cathode and anode being immersed in an aqueous hydrofluoric acid solution.
- a method for producing stannous fluoride free from substantial contamination with stannic fluoride which comprises passing an electric current between a mercury cathode and an anode of metallic tin havingsuperimposed thereon a thin layer of mercury-tin amalgam, said cathode and anode being immersed in an aqueous hydrofluoric acid solution of concentrations between about .9.% and about 15%.
- a continuous method for producingstannous'fluoride free from substantial contamination with stannic fluoride which comprises introducing an aqueous hydrofluoric acid solution into an electrolytic cell provided with a mercury cathode near the top thereof and a tin anode near the bottom thereof, the latter having superimposed thereon a thin layer of mercury-tin amalgam, passing an electric current between said anode and said cathode, continuously feeding hydrofluoric acid solution to the top portion of the cell and continuously withdrawing stannous fluoride solution from the bottom portion thereof.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
- Electroplating And Plating Baths Therefor (AREA)
- Electrolytic Production Of Metals (AREA)
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US401926A US3390064A (en) | 1964-10-06 | 1964-10-06 | Electrolytic process for preparing stannous fluoride |
| GB40645/65A GB1060817A (en) | 1964-10-06 | 1965-09-23 | Process for the production of stannous fluoride |
| FR33939A FR1528575A (fr) | 1964-10-06 | 1965-10-06 | Procédé électrolytique de production du fluorure stanneux à partir d'étain métallique |
| DEA50422A DE1300915B (de) | 1964-10-06 | 1965-10-06 | Verfahren zur Herstellung von Stannofluorid mit niedrigem Gehalt an Stannifluorid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US401926A US3390064A (en) | 1964-10-06 | 1964-10-06 | Electrolytic process for preparing stannous fluoride |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US3390064A true US3390064A (en) | 1968-06-25 |
Family
ID=23589821
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US401926A Expired - Lifetime US3390064A (en) | 1964-10-06 | 1964-10-06 | Electrolytic process for preparing stannous fluoride |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US3390064A (de) |
| DE (1) | DE1300915B (de) |
| GB (1) | GB1060817A (de) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3907653A (en) * | 1975-02-06 | 1975-09-23 | Pitt Metals And Chemicals Inc | Process for recovering tin salts from a halogen tin plate sludge |
| CN109368691A (zh) * | 2018-12-29 | 2019-02-22 | 广东光华科技股份有限公司 | 一种由二氧化锡制备氟化亚锡的方法 |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2713840C1 (ru) * | 2018-12-24 | 2020-02-07 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Юго-Западный государственный университет" (ЮЗГУ) | Способ получения фторида олова (II) из металла и его диоксида |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1597653A (en) * | 1925-01-12 | 1926-08-24 | Metal & Thermit Corp | Process of producing stannous chloride |
| US2673837A (en) * | 1949-06-22 | 1954-03-30 | Pennsylvania Salt Mfg Co | Electrolytic production of fluoborates |
| US3300397A (en) * | 1963-03-14 | 1967-01-24 | Allied Chem | Electrolytic production of metallic fluoborates |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2924508A (en) * | 1956-09-20 | 1960-02-09 | Ozark Mahoning Co | Method of production of stannous fluoride |
| US2955914A (en) * | 1957-08-26 | 1960-10-11 | Ozark Mahoning Co | Method of production of stannous fluoride |
-
1964
- 1964-10-06 US US401926A patent/US3390064A/en not_active Expired - Lifetime
-
1965
- 1965-09-23 GB GB40645/65A patent/GB1060817A/en not_active Expired
- 1965-10-06 DE DEA50422A patent/DE1300915B/de active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1597653A (en) * | 1925-01-12 | 1926-08-24 | Metal & Thermit Corp | Process of producing stannous chloride |
| US2673837A (en) * | 1949-06-22 | 1954-03-30 | Pennsylvania Salt Mfg Co | Electrolytic production of fluoborates |
| US3300397A (en) * | 1963-03-14 | 1967-01-24 | Allied Chem | Electrolytic production of metallic fluoborates |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3907653A (en) * | 1975-02-06 | 1975-09-23 | Pitt Metals And Chemicals Inc | Process for recovering tin salts from a halogen tin plate sludge |
| CN109368691A (zh) * | 2018-12-29 | 2019-02-22 | 广东光华科技股份有限公司 | 一种由二氧化锡制备氟化亚锡的方法 |
Also Published As
| Publication number | Publication date |
|---|---|
| GB1060817A (en) | 1967-03-08 |
| DE1300915B (de) | 1969-08-14 |
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