Patent US3677549A successfully refreshed from Google Patents.
Patent US3902889A successfully refreshed from Google Patents.
US3902889A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electric arc melting furnace
Assignee: United States Steel Corp
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Filing: 1972-11-30
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Granted: 1975-09-02
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Expires: 1992-11-30
Abstract
Abstract An apparatus for and a method of melting scrap metal and refining the melted scrap metal is disclosed. A. The improved apparatus includes an electric arc melting furnace having a shell provided with a mouth; a refractory lining on the shell; a removable roof for sealing the mouth; a melting electrode reciprocable through the roof into and out of contact with scrap metal; and a hearth lining defining with the furnace an upper level of the molten metal. A tuyere extends through the shell and the refractory lining flush with the refractory lining and has an inner pipe and a concentric outer pipe defining an annulus with the inner pipe. Charging means charge the furnace with the scrap metal. Melting means melt a hole in the scrap metal to produce molten metal. Blowing means blow an oxygen bearing gas from the inner pipe through the molten metal to decarburize the molten metal while simultaneously continuing to melt the scrap metal so that when the scrap metal has melted into molten metal the amount of residual carbon in the molten metal is approximately equal to, either more or less than, a predetermined desired amount of carbon, thereby reducing substantially the melting and refining cycle and producing heat exothermically by the chemical combination of the carbon in the molten metal with the oxygen in the oxygen bearing gas to aid in the melting of the scrap metal. B. The method of melting scrap metal and refining the melted molten metal in the electric-arc melting furnace having a shell provided with a mouth; a refractory lining on the shell; a removable roof for sealing the mouth; a melting electrode reciprocable through the roof into and out of contact with the scrap metal; a hearth line defining with the furnace an upper level of the molten metal; and a tuyere extending through the shell and the refractory lining flush with the refractory lining and having an inner pipe and a concentric outer pipe defining an annulus with the inner pipe, includes the steps of: A. CHARGING THE FURNACE WITH THE SCRAP METAL; B. MELTING A HOLE IN THE SCRAP METAL TO PRODUCE MOLTEN METAL; C. BLOWING AN OXYGEN BEARING GAS FROM THE INNER PIPE THROUGH THE MOLTEN METAL TO DECARBURIZE THE MOLTEN METAL WHILE SIMULTANEOUSLY CONTINUING TO MELT THE SCRAP METAL SO THAT WHEN THE SCRAP METAL HAS MELTED INTO MOLTEN METAL THE AMOUNT OF RESIDUAL CARBON IN THE MOLTEN METAL IS APPROXIMATELY EQUAL TO, EITHER MORE OR LESS THAN, A PREDETERMINED DESIRED AMOUNT OF CARBON THEREBY REDUCING SUBSTANTIALLY THE MELTING AND REFINING CYCLE AND PRODUCING HEAT EXOTHERMICALLY BY THE CHEMICAL COMBINATION OF THE CARBON IN THE MOLTEN METAL WITH THE OXYGEN IN THE OXYGEN BEARING GAS TO AID IN THE MELTING OF THE SCRAP METAL; AND D. REFINING THE MOLTEN METAL TO THE DESIRED METALLURGICAL COMPOSITION AND POURING TEMPERATURE.
Inventors
- 👤 Leonard E Malin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:44
CPC Classifications
C; C21; C21C; C21C5/00; C21C5/52; C21C5/5211; C21C5/5217; Y; Y02; Y02P; Y02P10/00; Y02P10/10; Y02P10/143; Y02P10/20
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
140 words
A METHOD OF MELTING SCRAP METAL AND REFINING THE MELTED MOLTEN METAL IN AN ELECTRIC ARC FURNACE HAVING A SHELL PROVIDED WITH A MOUTH, A REFRACTORY LINING ON SAID SHELL, A REMOVABLE ROOF FOR SEALING SAID MOUTH, A MELTING ELECTRODE RECIPROCABLE THROUGH SAID ROOF INTO AND OUT OF CONTACT WITH SAID SCRAP METAL, A HEARTH LINE DEFINING WITH SAID FURNACE AN UPPER LEVEL OF SAID MOLTEN METAL AND A TUYERE EXTENDING THROUGH SAID SHELL AND SAID REFRACTORY LINING FLUSH WITH SAID REFRACTORY LINING AND HAVING AN INNER PIPE AND A CONCENTRIC OUTER PIPE DEFINING AN ANNULUS WITH SAID INNER PIPE, SAID METHOD INCLUDING THE STEPS OF: A. CHARGING SAID FURNACE WITH SAID SCRAP METAL, B. MELTING A HOLE IN SAID SCRAP METAL TO PRODUCE MOLTEN METAL, C. ENERGIZING SAID ELECTRODE TO HEAT SAID SCRAP METAL WITH HEAT FROM SAID ELECTRODE,
Claim 2
Independent Claim
140 words
A METHOD OF MELTING SCRAP METAL AND REFINING THE MELTED MOLTEN METAL IN AN ELECTRIC ARC FURNACE HAVING A SHELL PROVIDED WITH A MOUTH, A REFRACTORY LINING ON SAID SHELL, A REMOVABLE ROOF FOR SEALING SAID MOUTH, A MELTING ELECTRODE RECIPROCABLE THROUGH SAID ROOF INTO AND OUT OF CONTACT WITH SAID SCRAP METAL, A HEARTH LINE DEFINING WITH SAID FURNACE AN UPPER LEVEL OF SAID MOLTEN METAL AND A TUYERE EXTENDING THROUGH SAID SHELL AND SAID REFRACTORY LINING FLUSH WITH SAID REFRACTORY LINING AND HAVING AN INNER PIPE AND A CONCENTRIC OUTER PIPE DEFINING AN ANNULUS WITH SAID INNER PIPE, SAID METHOD INCLUDING THE STEPS OF: A. CHARGING SAID FURNACE WITH SAID SCRAP METAL, B. MELTING A HOLE IN SAID SCRAP METAL TO PRODUCE MOLTEN METAL, C. ENERGIZING SAID ELECTRODE TO HEAT SAID SCRAP METAL WITH HEAT FROM SAID ELECTRODE,
Claim 3
Dependent Claim
27 words
The method recited in claim 1 including the step of: a. charging said furnace with said scrap metal up to a roof parting line of said furnace.
Claim 4
Dependent Claim
34 words
The method recited in claim 1 including the step of: a. melting a hole in said scrap metal by the addition of hot metal to said furnace to melt a portion of said scrap.
Claim 5
Dependent Claim
25 words
The method recited in claim 1 including the step of melting a hole in said scrap metal with said melting electrode to produce molten metal.
Claim 6
Dependent Claim
51 words
The method recited in claim 1 including the step of: a. blowing a shroud gas through said annulus while blowing said oxygen bearing gas through said inner pipe to cool said inner pipe and prevent burning of the end of said inner pipe below the inner surface of said refractory lining.
Claim 7
Dependent Claim
48 words
The method recited in claim 1 including the step of: a. blowing said oxygen bearing gas from the side of said furnace through said molten metal radially with respect to a hearth zone of sAid furnace defined by said hearth line and the bottom of said refractory lining.
Claim 8
Dependent Claim
54 words
The method recited in claim 1 including the step of: a. blowing said oxygen bearing gas through said molten metal from the side of the furnace downwardly at an angle with respect to said hearth line to provide the longest path of said oxygen bearing gas to an opposite wall of said refractory lining.
Claim 9
Dependent Claim
53 words
The method recited in claim 1 including the steps of: a. blowing said oxygen bearing gas from the side of said furnace through said molten metal tangentially with respect to a furnace bottom of said furnace to create a vortex of molten metal in more intimate heat transfer relation with said scrap metal.
Claim 10
Dependent Claim
26 words
The method recited in claim 1 including the step of: a. blowing said oxygen bearing gas through said molten metal from the bottom of said furnace.
Claim 11
Dependent Claim
37 words
The method recited in claim 1 including the step of: a. blowing said oxygen bearing gas from the bottom of said furnace through said molten metal at an angle inclined to the vertical axis of said furnace.
Claim 12
Dependent Claim
20 words
The method recited in claim 1 including the step of: a. evacuating said furnace during said melting, decarburization and refining.
Claim 13
Dependent Claim
45 words
The method recited in claim 11 including the step of: a. combining the air sucked into the furnace from openings therein with the carbon monoxide produced above the molten metal to form carbon dioxide thereby adding further heat to the melting of the scrap metal.
Claim 14
Dependent Claim
32 words
The method recited in claim 1 including the step of: a. adding a fluxing agent through said inner pipe to said molten metal thereby removing sulfur and phosphorus from said molten metal.
Claim 15
Dependent Claim
35 words
The method recited in claim 1 including the step of: a. adding a liquefying agent through said inner pipe to said molten metal thereby lowering the viscosity of a slag formed on said molten metal.
Claim 16
Dependent Claim
32 words
The method recited in claim 1 including the step of: a. adding a deoxidizing agent through said inner pipe to said molten metal thereby stopping the oxidizing process in said molten metal.
Claim 17
Dependent Claim
94 words
The method recited in claim 1 including the step of: a. blowing an inert gas through said annulus into a stainless steel molten metal to lower the partial pressure of carbon monoxide in said molten metal so that the oxygen in said oxygen bearing gas combines with the carbon in said molten metal rather than with the chromium in said molten metal to produce a desired stainless steel thereby reducing to a minimum the amount of alloying agent required to cause the chromium to combine with the nickel in said stainless steel molten metal.
Claim 18
Dependent Claim
36 words
The method recited in claim 1 including the step of: a. confining said molten metal in a protective chamber adjacent said tuyere and on said shell in the event of a burn out of said tuyere.
Claim 19
Dependent Claim
19 words
The method recited in claim 17 including the step of: a. discharging said molten metal from said protective chamber.
Claim 20
Dependent Claim
31 words
The method recited in claim 1 including the step of: a. superheating the molten metal so that the temperature of said molten metal approaches the temperature of said melted scrap metal.
Claim 21
Dependent Claim
205 words
An electric arc furnace having: a. a shell provided with a mouth; b. a refractory lining on said shell; c. a removable roof for sealing said mouth; d. a hearth line defining with said furnace an upper level of said molten metal; e. a tuyere extending through said shell and said refractory lining terminating flush with said refractory lining and having an inner pipe and a concentric outer pipe defining an annulus with said inner pipe; f. means for charging said furnace with said scrap metal; g. means for melting a hole in said scrap metal to produce molten metal; and h. means for blowing an oxygen bearing gas from said inner pipe through said molten metal to decarburize said molten metal while simultaneously continuing to melt said scrap metal so that when said scrap metal has melted into molTen metal the amount of residual carbon in said molten metal is approximately equal to, either more or less than, a predetermined desired amount of carbon, thereby reducing substantially the melting and refining cycle and producing heat exothermically by the chemical combination of the carbon in the molten metal with the oxygen in the oxygen bearing gas to aid in the melting of said scrap metal.
Claim 22
Dependent Claim
205 words
An electric arc furnace having: a. a shell provided with a mouth; b. a refractory lining on said shell; c. a removable roof for sealing said mouth; d. a hearth line defining with said furnace an upper level of said molten metal; e. a tuyere extending through said shell and said refractory lining terminating flush with said refractory lining and having an inner pipe and a concentric outer pipe defining an annulus with said inner pipe; f. means for charging said furnace with said scrap metal; g. means for melting a hole in said scrap metal to produce molten metal; and h. means for blowing an oxygen bearing gas from said inner pipe through said molten metal to decarburize said molten metal while simultaneously continuing to melt said scrap metal so that when said scrap metal has melted into molTen metal the amount of residual carbon in said molten metal is approximately equal to, either more or less than, a predetermined desired amount of carbon, thereby reducing substantially the melting and refining cycle and producing heat exothermically by the chemical combination of the carbon in the molten metal with the oxygen in the oxygen bearing gas to aid in the melting of said scrap metal.
Claim 23
Dependent Claim
29 words
The electric arc furnace recited in claim 20 wherein: a. said charging means charges said furnace with said scrap metal up to a roof parting line of said furnace.
Claim 24
Dependent Claim
33 words
The electric arc furnace recited in claim 20 wherein: a. said melting means includes an electrode which contacts said scrap metal and melts said scrap metal to produce molten metal in said furnace.
Claim 25
Dependent Claim
36 words
The electric arc furnace recited in claim 20 wherein: a. said melting means includes means for pouring molten metal into contact with said scrap metal to produce molten metal from said scrap metal in said furnace.
Claim 26
Dependent Claim
43 words
The electric arc furnace recited in claim 20 wherein: a. said blowing means blows a shroud gas through said annulus to cool said inner pipe and prevent burning of the end of said inner pipe below the inner surface of said refractory lining.
Claim 27
Dependent Claim
39 words
The electric arc furnace recited in claim 20 wherein: a. said tuyere is disposed radially in said furnace with respect to a hearth zone of said furnace defined by said hearth lining and the bottom of said refractory lining.
Claim 28
Dependent Claim
48 words
The electric arc furnace recited in claim 20 wherein: a. said tuyere is disposed in the side of said furnace downwardly at an angle with respect to said hearth line to provide the longest path of said oxygen bearing gas to an opposite wall of said refractory lining.
Claim 29
Dependent Claim
49 words
The electric arc furnace recited in claim 20 wherein: a. said tuyere is disposed in the side of said furnace and directed tangentially with respect to a furnace bottom of said furnace to create a vortex of molten metal in more intimate heat transfer relationship with said scrap metal.
Claim 30
Dependent Claim
20 words
The electric arc furnace recited in claim 20 wherein: a. said tuyere is disposed in the bottom of said furnace.
Claim 31
Dependent Claim
33 words
The electric arc furnace recited in claim 20 wherein: a. said tuyere is disposed in the bottom of said furnace and is inclined at an angle to the vertical axis of said furnace.
Claim 32
Dependent Claim
29 words
The electric arc furnace recited in claim 20 and having: a. evacuating means associated with said furnace for evacuating the interior of said furnace during melting, decarburizing and refining.
Claim 33
Dependent Claim
53 words
The electric arc furnace recited in claim 30 wherein: a. said evacuating means sucks into the furnace ambient air through openings therein to cause said ambient air to combine with the carbon monoxide produced above said molten metal to form carbon dioxide thereby adding further heat to the melting of the scrap metal.
Claim 34
Dependent Claim
40 words
The electric arc furnace recited in claim 20 and having: a. fluxing means associated with said blowing means for adding a fluxing agent through said inner pipe to said molten metal thereby removing sulfur and phosphorus from said molten metal.
Claim 35
Dependent Claim
43 words
The electric arc furnace recited in claim 20 and having: a. liquefying means associated with said blowing means for adding a liquefying agent through said inner pipe to said molten metal thereby lowering the viscosity of a slag formed on said molten metal.
Claim 36
Dependent Claim
39 words
The electric arc furnace recited in claim 20 and having: a. deoxidizing means associated with said blowing means for adding a deoxidizing agent through said inner pipe to said molten metal thereby stopping the oxidizing in said molten metal.
Claim 37
Dependent Claim
96 words
The electric arc furnace recited in claim 20 wherein: a. said blowing means blows an inert gas through said annulus into a stainless steel molten metal to lower the partial pressure of the carbon monoxide in said molten metal so that the oxygen in said oxygen bearing gas combines with the carbon in said molten metal, ratheR than the chromium in said molten metal, to produce a desired stainless steel thereby reducing to a minimum the amount of alloying agent required to cause the chromium to combine with the nickel in said stainless steel molten metal.
Claim 38
Dependent Claim
41 words
The electric arc furnace recited in claim 20 and having: a. a protective chamber disposed about the inlet of said tuyere and on said shell for receiving said molten metal from said furnace when a burn out of said tuyere occurs.
Claim 39
Dependent Claim
26 words
The electric arc furnace recited in claim 36 and having: a. discharge means for discharging said molten metal from said protective chamber to a disposal means.
Claim 40
Dependent Claim
37 words
The electric arc furnace recited in claim 20 wherein: a. said blowing means and said melting means superheats said molten metal so that the temperature of said molten metal approaches the temperature of said melted scrap metal.
Claim 41
Dependent Claim
143 words
An improved method of melting steel scrap and refining steel in an electric arc furnace having at least one electrode, comprising the steps of: charging the furnace with steel scrap; heating said scrap with said electrode to melt said scrap and provide a level of molten metal in said furnace; blowing an oxygen bearing gas through a first tuyere submerged beneath the level of the liquid metal into the liquid metal to chemically react with the carbon and other constituents of the metal thereby oxidizing the carbon and other constituents and generating heat simultaneously with the heating by said electrode of said scrap; blowing a shroud gas through an annulus around said first tuyere formed by a second concentric outer tuyere to cool said first tuyere and minimize its wear; and refining said molten metal to the desired metallurgical composition and pouring temperature.
Claim 42
Dependent Claim
143 words
An improved method of melting steel scrap and refining steel in an electric arc furnace having at least one electrode, comprising the steps of: charging the furnace with steel scrap; heating said scrap with said electrode to melt said scrap and provide a level of molten metal in said furnace; blowing an oxygen bearing gas through a first tuyere submerged beneath the level of the liquid metal into the liquid metal to chemically react with the carbon and other constituents of the metal thereby oxidizing the carbon and other constituents and generating heat simultaneously with the heating by said electrode of said scrap; blowing a shroud gas through an annulus around said first tuyere formed by a second concentric outer tuyere to cool said first tuyere and minimize its wear; and refining said molten metal to the desired metallurgical composition and pouring temperature.
References Cited (Backward Citations)
US2855293A
Cited
US3079247A
Cited
US3472650A
Cited
US3459867A
Cited
US3706549A
Cited
US3708599A
Cited
US3812275A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-01 | 1979-03-03 | 1979-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-01 | 1983-03-03 | 1983-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-01 | 1987-03-03 | 1987-09-02 | $7700.00 | Window Closed / Lapsed |