US3953263A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preventing the formation of nitrogen monoxide in treatment of metals with nitric acid or mixed acid
Assignee: Hitachi Ltd
•
Filing: 1973-11-26
•
Granted: 1976-04-27
•
Expires: 1993-11-26
Abstract
Abstract The formation of nitrogen monoxide in treatment of metals with nitric acid or a mixed acid can be prevented by adding at least one of ammonium peroxodisulfate and hydrogen peroxide to nitric acid or a mixed acid consisting mainly of nitric acid and sulfuric acid.
Inventors
- 👤 Misao Ishikawa
- 👤 Rokuro Tsuji
- 👤 Norihisa Yoshimori
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:56
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/10; C23F1/14; C23F1/16; C23F1/26; C23F3/00; C23F3/04; C23F3/06; C23G; C23G1/00; C23G1/02
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
82 words
In a process for dissolving a molybdenum core from a coil heater by dipping said coil heater in a resolving solution containing nitric acid and water as main components, said coil heater being prepared by winding tungsten wire around said molybdenum core, applying an alumina insulator onto the tungsten wire and sintering the applied alumina insulator, the improvement comprising adding sufficient ammonium peroxodisulfate to said resolving solution so that the formation of nitrogen monoxide during dissolution of the molybdenum core is prevented.
Claim 2
Dependent Claim
82 words
In a process for dissolving a molybdenum core from a coil heater by dipping said coil heater in a resolving solution containing nitric acid and water as main components, said coil heater being prepared by winding tungsten wire around said molybdenum core, applying an alumina insulator onto the tungsten wire and sintering the applied alumina insulator, the improvement comprising adding sufficient ammonium peroxodisulfate to said resolving solution so that the formation of nitrogen monoxide during dissolution of the molybdenum core is prevented.
Claim 3
Dependent Claim
12 words
The process of claim 1, wherein said resolving solution contains sulfuric acid.
Claim 4
Dependent Claim
18 words
The process of claim 1, wherein said resolving solution consists essentially of water, nitric acid and ammonium peroxodisulfate.
Claim 5
Dependent Claim
35 words
The process of claim 1, wherein said resolving solution is an aqueous solution containing about 17 parts by volume of 67% HNO 3 and 7.5 parts by volume of 98% H 2 SO 4 .
Claim 6
Dependent Claim
48 words
The process of claim 4, wherein said resolving solution contains about 43 grams of ammonium peroxodisulfate for each 200 cc of the mixed acid obtained by mixing 17 parts by volume of 67% HNO 3 and 7.5 parts by volume of a 98% H 2 SO 4 .
References Cited (Backward Citations)
US2762728A
Cited
US2965521A
Cited
US2978301A
Cited
US3094489A
Cited
US3293093A
Cited
US3373113A
Cited
US3463733A
Cited
US3476624A
Cited
US3556883A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-04-27 | 1979-10-27 | 1980-04-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-04-27 | 1983-10-27 | 1984-04-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-04-27 | 1987-10-27 | 1988-04-27 | $7700.00 | Window Closed / Lapsed |