US3898079A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Refining of stainless steels
Assignee: Uddeholms AB
•
Filing: 1973-10-05
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Granted: 1975-08-05
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Expires: 1993-10-05
Abstract
Abstract In a process for refining stainless steel where oxygen and ammonia are introduced into a molten steel, e.g. for decarburisation and/or introducing nitrogen into the steel, the ammonia is introduced separately from the oxygen through a tuyere comprising at least two co-axial pipes. The ammonia is preferably introduced through a pipe which is not an outermost pipe. This procedure reduces the risk of the melt solidifying around the ammonia pipe and avoids the need to use combustible oxygen/ammonia mixtures.
Inventors
- 👤 Lars Anders Eriksson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 02:15
CPC Classifications
C; C21; C21C; C21C5/00; C21C5/28; C21C5/42; C21C5/46; C21C5/4606; C21C7/00; C21C7/04; C21C7/068; C21C7/0685; C22; C22C; C22C33/00
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
77 words
A PROCESS FOR REFINING A STEEL CONTAINING CHROMIUM WHICH COMPRISES SIMULTANEOUSLY INTRODUCING MOLECULAR OXYGEN AND AMMONIA INTO THE STEEL IN A MOLTEN CONDITION, THE OXYGEN AND AMMONIA BEING INTRODUCED SEPARATELY FROM ONE ANOTHER THROUGH DIFFERENT SECTIONS OF A TUYERE COMPRISING AT LEAST TWO COAXIAL PIPES AND PRESENTING AN INNERMOST SECTION AND AN OUTERMOST SECTION, THE AMMONIA BEING INTRODUCED THROUGH A SECTION OF TUYERE OTHER THAN THE OUTERMOST SECTION AND THE OXYGEN BEING INTRODUCED THROUGH THE OUTERMOST SECTION.
Claim 2
Dependent Claim
77 words
A PROCESS FOR REFINING A STEEL CONTAINING CHROMIUM WHICH COMPRISES SIMULTANEOUSLY INTRODUCING MOLECULAR OXYGEN AND AMMONIA INTO THE STEEL IN A MOLTEN CONDITION, THE OXYGEN AND AMMONIA BEING INTRODUCED SEPARATELY FROM ONE ANOTHER THROUGH DIFFERENT SECTIONS OF A TUYERE COMPRISING AT LEAST TWO COAXIAL PIPES AND PRESENTING AN INNERMOST SECTION AND AN OUTERMOST SECTION, THE AMMONIA BEING INTRODUCED THROUGH A SECTION OF TUYERE OTHER THAN THE OUTERMOST SECTION AND THE OXYGEN BEING INTRODUCED THROUGH THE OUTERMOST SECTION.
Claim 3
Dependent Claim
49 words
A process according to claim 1 wherein the tuyere comprises three coaxial pipes and presents an innermost section, an intermediate section and an outermost section and ammonia is introduced through at least one of the innermost and intermediate sections and oxygen is introduced at least through the outermost section.
Claim 4
Dependent Claim
23 words
A process according to claim 1 wherein a mixture of ammonia and steam is introduced through a section other than the outermost section.
Claim 5
Dependent Claim
25 words
A process according to claim 2 wherein a mixture of ammonia and steam is introduced through at least one of the innermost and intermediate sections.
References Cited (Backward Citations)
US3330645A
Cited
US3706549A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-08-04 | 1979-02-03 | 1979-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-04 | 1983-02-03 | 1983-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-04 | 1987-02-03 | 1987-08-05 | $7700.00 | Window Closed / Lapsed |