US4565675A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for treating and recovering pickling waste liquids for stainless steel
Assignee: Solex Research Corp
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Filing: 1985-03-20
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Granted: 1986-01-21
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Expires: 2005-03-20
Abstract
Abstract A process for treating and recovering pickling waste liquids used for the pickling of stainless steel such as nitric-hydrofluoric acid, nitric acid, hydrochloric acid and, sulfuric acid is disclosed, which comprises recovering the nitric-hydrofluoric acid and the iron oxide or metallic ion from the waste liquids of nitric-hydrofluoric acid and nitric acid by two solvent extraction processes and recovering the Cr and Ni containing ferrite from the waste liquids of sulfuric acid or hydrochloric acid by a ferrite formation process. When the waste acid is sulfuric acid, gypsum of a high purity can be obtained.
Inventors
- 👤 Kazuhiro Uchino
- 👤 Toshio Watanabe
- 👤 Yoshio Nakazato
- 👤 Minoru Hoshino
- 👤 Noboru Ishihara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 18:25
CPC Classifications
C; C23; C23G; C23G1/00; C23G1/36; C01; C01F; C01F11/00; C01F11/46; C01G; C01G49/00; C01G49/0009; C01G49/009; C01G53/00; C01G53/80; C01G53/84; C01P; C01P2002/00; C01P2002/30; C01P2002/32; C01P2006/00; C01P2006/42; C01P2006/60; C01P2006/80; C01P2006/82; Y; Y10; Y10S; Y10S423/00; Y10S423/01; Y10S423/02
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
112 words
A process for treating and recovering nitric-hydrofluoric acid, nitric acid and hydrochloric acid waste liquids used for the pickling of stainless steel, which comprises removing Fe 3+ from the nitric-hydrofluoric acid and nitric acid waste liquids by a solvent extraction process to recover it as an iron oxide or a metallic iron, recovering the nitric acid and the hydrofluoric acid by another solvent extraction process, converting the remaining ions of Cr and Ni into a hydroxide by adding an alkali, and recovering them as ferromagnetic oxides by a ferrite formation process using the hydrochloric acid waste liquid as an acid for resolving the hydroxide and an ion source of Fe 2+ .
Claim 2
Dependent Claim
112 words
A process for treating and recovering nitric-hydrofluoric acid, nitric acid and hydrochloric acid waste liquids used for the pickling of stainless steel, which comprises removing Fe 3+ from the nitric-hydrofluoric acid and nitric acid waste liquids by a solvent extraction process to recover it as an iron oxide or a metallic iron, recovering the nitric acid and the hydrofluoric acid by another solvent extraction process, converting the remaining ions of Cr and Ni into a hydroxide by adding an alkali, and recovering them as ferromagnetic oxides by a ferrite formation process using the hydrochloric acid waste liquid as an acid for resolving the hydroxide and an ion source of Fe 2+ .
Claim 3
Dependent Claim
131 words
A process for treating and recovering nitric-hydrofluoric acid, nitric acid and sulfuric acid waste liquids used for the pickling of stainless steel, which comprises removing Fe 3+ from the nitric-hydrofluoric acid and nitric acid waste liquids by a solvent extraction process to recover it as an iron oxide or a metallic iron, recovering the nitric acid and the hydrofluoric acid by another solvent extraction process, converting the remaining ions of Cr and Ni into a hydroxide by adding an alkali, recovering them as ferromagnetic oxides by a ferrite formation process using the sulfuric acid waste liquid as an acid for resolving the hydroxide and an ion source of Fe 2+ , and recovering as a gypsum a sulfate group included in the filtrate after the treatment for the ferrite formation process.
Claim 4
Dependent Claim
131 words
A process for treating and recovering nitric-hydrofluoric acid, nitric acid and sulfuric acid waste liquids used for the pickling of stainless steel, which comprises removing Fe 3+ from the nitric-hydrofluoric acid and nitric acid waste liquids by a solvent extraction process to recover it as an iron oxide or a metallic iron, recovering the nitric acid and the hydrofluoric acid by another solvent extraction process, converting the remaining ions of Cr and Ni into a hydroxide by adding an alkali, recovering them as ferromagnetic oxides by a ferrite formation process using the sulfuric acid waste liquid as an acid for resolving the hydroxide and an ion source of Fe 2+ , and recovering as a gypsum a sulfate group included in the filtrate after the treatment for the ferrite formation process.
References Cited (Backward Citations)
US3927173A
Cited
US4166098A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-01-20 | 1989-07-22 | 1990-01-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-01-20 | 1993-07-22 | 1994-01-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-01-20 | 1997-07-22 | 1998-01-21 | $7700.00 | Window Closed / Lapsed |