US3980469A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of desulfurization of a steel melt
Assignee: Thyssen Niederrhein AG
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Filing: 1974-04-17
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Granted: 1976-09-14
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Expires: 1994-04-17
Abstract
Abstract A steel melt is confined and subjected to a partial vacuum. A particulate additive is entrained by a neutral nonreactive carrier gas and introduced into the melt below the surface thereof at a depth such that the additive is immediately vaporized and rises toward the surface of the melt in the form of bubbles which react with components of the melt. With particulate calcium as the additive an injection depth 1500 mm, a temperature of approximately 1500°C, and a vacuum of 20 Torr allows the sulfur content of a steel melt readily to be reduced below 0.005% by weight.
Inventors
- 👤 Eckehard Forster
- 👤 Helmut Richter
- 👤 Edgar Spetzler
- 👤 Jochen Wendorff
- 👤 Wilhelm Klapdar
- 👤 Heinrich-Wilhelm Rommerswinkel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 11:45
CPC Classifications
C; C21; C21C; C21C7/00; C21C7/10; C21C7/0037
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
89 words
A method of desulfurizing a ferrous melt comprising the steps of applying suction to the upper surface of said melt to subject it to subatmospheric pressure of substantially 15 to 25 Torr; simultaneously introducing a particulate additive consisting essentially of calcium and vaporizable at the temperature of said melt into said melt at a depth of substantially 1200 to 1800 mm below said surface thereof permitting vaporization of said additive; and vaporizing the introduced additive at the melt temperature while suction continues to be applied at said upper surface.
Claim 2
Independent Claim
89 words
A method of desulfurizing a ferrous melt comprising the steps of applying suction to the upper surface of said melt to subject it to subatmospheric pressure of substantially 15 to 25 Torr; simultaneously introducing a particulate additive consisting essentially of calcium and vaporizable at the temperature of said melt into said melt at a depth of substantially 1200 to 1800 mm below said surface thereof permitting vaporization of said additive; and vaporizing the introduced additive at the melt temperature while suction continues to be applied at said upper surface.
Claim 3
Dependent Claim
35 words
The method defined in claim 1, further comprising the step of entraining said additive with a carrier gas and introducing said additive into said melt by blowing same into said melt with said carrier gas.
Claim 4
Dependent Claim
27 words
The method defined in claim 1, further comprising the step of forming on said upper surface a slag and absorbing therewith nongaseous reaction products of said melt.
Claim 5
Dependent Claim
42 words
The method defined in claim 1 wherein said vacuum is formed by drawing a portion of said melt up through a riser tube into a treatment chamber through evacuation of said chamber, said additive being introduced into said melt in said riser.
Claim 6
Dependent Claim
25 words
The method defined in claim 4, further comprising the step of raising and lowering said treatment chamber and introducing said additive only during raising thereof.
References Cited (Backward Citations)
US3001864A
Cited
US3060015A
Cited
US3512957A
Cited
US3367646A
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US3467167A
Cited
US3545960A
Cited
US3575695A
Cited
US3547622A
Cited
US3598383A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-09-14 | 1980-03-15 | 1980-09-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-09-14 | 1984-03-15 | 1984-09-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-09-14 | 1988-03-15 | 1988-09-14 | $7700.00 | Window Closed / Lapsed |