US3635664A
Expired / Lapsed
US
⏱️ 0.0 years remaining
REGENERATION OF HYDROCHLORIC ACID PICKLING WASTE BY H{11 SO{11 {0 ADDITION, DISTILLATION AND FeSO{11 {0 Precipitation
Assignee: Daido Chemical Engineering Corp
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Filing: 1970-05-06
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Granted: 1972-01-18
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Expires: 1990-05-06
Abstract
Abstract In recovering hydrochloric acid from a spent hydrochloric acid pickle liquor the process is characterized by adding sulfuric acid to hydrochloric acid waste to convert FeC12 in said waste to HCl and FeSO4 and to obtain a mixture containing at least 38 percent by weight of free sulfuric acid, distilling said resultant mixture to vaporize substantially all of the HCl therefrom together with water and to precipitate ferrous sulfate, condensing said HCl and water thus vaporized to recover hydrochloric acid, separating the precipitated ferrous sulfate from the residual liquid and circulating the resultant liquid free of ferrous sulfate as a sulfuric acid source.
Inventors
- 👤 Yasuo Morimoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:43
CPC Classifications
C; C23; C23G; C23G1/00; C23G1/36; C01; C01B; C01B7/00; C01B7/01; C01G; C01G49/00; C01G49/14; Y; Y10; Y10S; Y10S203/00; Y10S203/11; Y10S423/00; Y10S423/01; Y10S423/02
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
21 words
distilling said resultant mixture to vaporize substantially all amount of the HCl therefrom together with water and to precipitate ferrous sulfate;
Claim 2
Dependent Claim
57 words
The method as claimed in claim 1 wherein said mixture of waste hydrochloric acid and sulfuric acid is first subjected to flash distillation under reduced pressure to vaporize a major portion of HCl from the acid waste and the residual liquid thereby obtained is further distilled to vaporize the rest of HCl and to precipitate ferrous sulfate.
Claim 3
Dependent Claim
56 words
The method as claimed in claim 1 wherein said mixture of hydrochloric acid waste and sulfuric acid is subjected to steam distillation to vaporize substantially all of the HCl from said hydrochloric acid waste and the residual liquid thereby obtained is concentrated to remove a part of water from the system and to precipitate ferrous sulfate.
Claim 4
Dependent Claim
22 words
condensing said HCl and water thus vaporized to recover hydrochloric acid; 4. separating the precipitated ferrous sulfate from the residual liquid; and
Claim 5
Dependent Claim
30 words
The method as claimed in claim 3 wherein said steam distillation is carried out by utilizing a part of the water vapor produced by the concentration of said residual liquid.
Claim 6
Dependent Claim
13 words
circulating the resultant liquid free of ferrous sulfate as a sulfuric acid source.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-17 | 1975-07-19 | 1976-01-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-17 | 1979-07-19 | 1980-01-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-17 | 1983-07-19 | 1984-01-18 | $7700.00 | Window Closed / Lapsed |