US4125594A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Purification of hydrofluoric acid etching solutions with weak anion exchange resins
Assignee: Corning Glass Works
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Filing: 1976-12-22
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Granted: 1978-11-14
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Expires: 1996-12-22
Abstract
Abstract A method for purifying a spent hydrofluoric acid etching solution containing siliceous by-products which comprises treating the solution with a weak anion exchange resin of the polyamine type to remove SiF 6 = ions therefrom is described. The anion exchange resin may be regenerated with aqueous NaOH.
Inventors
- 👤 Yao-Sin Su
- 👤 Ken F. Sugawara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:13
CPC Classifications
C; C01; C01B; C01B7/00; C01B7/19; C01B7/191; C01B7/195; C01B7/197; C01B7/198
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
89 words
A method for purifying a spent hydrofluoric acid glass etching solution containing up to about 13% HF by weight and containing fluosilicic acid by removing SiF 6 = ions therefrom which comprises the steps of treating said spent solution with a weak anion exchange resin of the polyamine type in the fluoride salt form to remove said SiF 6 = ions, thereafter regenerating the weak anion exchange resin with an aqueous solution of NaOH and then converting the regenerated weak anion exchange resin back to the fluoride salt from.
Claim 2
Independent Claim
89 words
A method for purifying a spent hydrofluoric acid glass etching solution containing up to about 13% HF by weight and containing fluosilicic acid by removing SiF 6 = ions therefrom which comprises the steps of treating said spent solution with a weak anion exchange resin of the polyamine type in the fluoride salt form to remove said SiF 6 = ions, thereafter regenerating the weak anion exchange resin with an aqueous solution of NaOH and then converting the regenerated weak anion exchange resin back to the fluoride salt from.
Claim 3
Dependent Claim
23 words
A method according to claim 1 wherein the spent hydrofluoric acid solution contains up to about 35 grams per liter of fluosilicic acid.
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) | 1981-11-13 | 1982-05-15 | 1982-11-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-11-13 | 1986-05-15 | 1986-11-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-11-13 | 1990-05-15 | 1990-11-14 | $7700.00 | Window Closed / Lapsed |