US3844768A - Process for refining alloy steels containing chromium and including stainless steels - Google Patents

Process for refining alloy steels containing chromium and including stainless steels Download PDF

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Publication number
US3844768A
US3844768A US00247315A US24731572A US3844768A US 3844768 A US3844768 A US 3844768A US 00247315 A US00247315 A US 00247315A US 24731572 A US24731572 A US 24731572A US 3844768 A US3844768 A US 3844768A
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United States
Prior art keywords
flow
process according
tuyere
fluid
supplied
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Expired - Lifetime
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US00247315A
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J Morlet
J Saleil
P Leroy
M Cadart
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Creusot Loire SA
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Creusot Loire SA
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Priority claimed from FR7119463A external-priority patent/FR2139642A1/fr
Priority claimed from FR7127015A external-priority patent/FR2146900A1/fr
Priority claimed from FR7127016A external-priority patent/FR2147795A1/fr
Priority claimed from FR7206824A external-priority patent/FR2173717A2/fr
Application filed by Creusot Loire SA filed Critical Creusot Loire SA
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/005—Manufacture of stainless steel
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/068—Decarburising
    • C21C7/0685—Decarburising of stainless steel

Definitions

  • ABSTRACT An alloy steel containing chromium is refined by blowing fluids into the molten steel through double or triple feed tuyeres. Each tuyere first provides a flow of an oxidizing fluid, a second flow of a fluid for diluting the carbon monoxide in the bath and a third peripheral flow of a carbon make-up liquid.
  • Operation at a reduced carbon monoxide pressure is also known and there are two different ways of achieving the reduced pressure in conventional processes.
  • One method involves blowing the metal with oxygen in vacuo, and the other method involves blowing into the bath oxygen diluted with a neutral gas such as argon which, unlike nitrogen (although more expensive than nitrogen), does not lead to the formation of nitrides.
  • a neutral gas such as argon which, unlike nitrogen (although more expensive than nitrogen)
  • a process for refining an alloy steel containing chromium which comprises blowing fluids into the molten steel through at least one double or triple feed tuyere, the or each tuyere providing a first flow of an oxidising fluid, a second flow of a fluid for diluting the carbon monoxide in the bath, and a third peripheral flow, which is separate from the said first and second flows, of a carbon make-up liquid.
  • FIG. 1 shows a tuyere of concentric tubes with the protecting liquid admitted between the tubes and the oxidizing and diluent fluid admitted to the inner tube;
  • FIG. 2 shows a triple concentric tuyere with the oxidizing fluid admitted to the central tube; the diluent fluid admitted to the next outer tube; and the protecting fluid admitted to the outer tube; and
  • FIG. 3 is a variant of FIG. 2 in which the tubes for admission of the diluent fluid and the oxidizing fluid are reversed.
  • At least one double tuyere is used, to the inner circuit of which is supplied a mixture of the diluent fluid and oxidising fluid.
  • at least one triple tuyere is used and the oxidising fluid and the diluent fluid are introduced separately into two separate inner circuits of the or each triple tuyere.
  • either a primary flow of the oxidising fluid is supplied to the centre of the tuyere, a secondary flow of the diluent fluid is supplied in a separate circuit around the primary flow, and a tertiary flow of the carbon makeup liquid is supplied at the periphery of the tuyere, or a primary flow of the diluent fluid is supplied to the centre of the tuyere, a secondary flow of the oxidising fluid is supplied in a separate circuit around the primary flow, and a tertiary flow of the carbon make-up liquid is supplied to the periphery of the tuyere.
  • the diluent fluid can be a neutral gas such as argon or a fluid (such as water vapour) which dissociates, associates or reacts upon contact with the molten metal, to produce a diluent gas.
  • the diluent fluid can be an emulsion or an aerosol.
  • the diluent fluid is a spray of water droplets in a vehicle gas, which can be the oxidising gas itself or a diluent gas or any other appropriate gas.
  • the oxidising fluid may be, for example, industrially pure oxygen, air or oxygen-enriched air.
  • the steel is refined in two stages, and in the first stage the flow of diluent fluid is zero being replaced by an oxidising fluid flow, and, in the second stage, the diluent fluid flow increases until It is more than twice the oxidising fluid flow.
  • the proportion of diluent may be, for example, percent and the proportion of oxidising fluid (correspondingly) 30 percent.
  • the carbon content of the metal at the end of the first stage of refining is preferably from 0.150 to 0.700 percent, more preferably approximately 0.400 percent, and the temperature of the metal approximately 1,600C and a chromium content of the metal approximately 18 percent.
  • the carbon make-up liquid may be any liquid which reduces the corrosive wear on the tuyeres. It is preferably a hydrocarbon-containing liquid, one example of such a liquid being fuel oil. An emulsion or argon or water vapour or water droplets in fuel oil may also be used.
  • the proportion by weight of fuel oil flow relative to the oxygen flow is preferably from 1 to 10 percent, more preferably from 2.5 to 4 percent. This proportion may be either constant or may be varied during the refining process.
  • the vessel in which the refining process according to the invention is performed may be in vacuo or under a reduced pressure, or at atmospheric pressure.
  • One of the main advantages of the process of the invention is that the task of tuyere protection (performed by the carbon make-up liquid) is divorced from the function of diluting the bath decarburization carbon monoxide (the latter being performed either by a neutral gas or by a dissociation product of a fluid). In the first place, therefore, the working life of the tuyeres can be substantially improved, e.g., up to several times longer than that of tuyeres blowing only oxygen and argon.
  • the invention makes it possible in the first stage of a refining operation to blow pure oxygen without a neutral gas, for much of the time of the refining operation, for instance, in the case of an 18 percent bath chromium content, for as long as the bath carbon content does not drop below 0.400 percent, for instance, at a temperature of 1,600C.
  • Another advantage of the invention is that a heavy concentration of a neutral gas, such as argon, and hence a low concentration of oxygen can be used at the end of the decarburization, thus reducing chromium losses still further without greatly impairing the overall thermal balance of refining, since pure oxygen without argon can be blown during the first stage of refining and thus pave the way for a good thermal balance.
  • a neutral gas such as argon
  • Another advantage of the invention is that argon consumption is much less than in known processes using argon and oxygen all the time even though, according to the invention, about 70 percent argon is used at the end of refining.
  • the reason for this reduction is that oxygen is blown pure without argon during a relatively long first stage of refining.
  • An intermediate phase using ordinary air or, preferably, oxygen-enriched air can be included; it must be fairly brief, otherwise nitriding may become excessive.
  • Another advantage of the invention is that argon can be completely omitted and water vapour or water spray used instead of argon, for the non-dissociated portion of water vapour or water spray and the hydrogen evolved from the dissociated portion both help to dilute the carbon monoxide and (effectively) reduce the partial pressure thereof.
  • Another advantage of the invention is that, as starting material, an alloy of high carbon content, even cast iron, can be used without a heavy consumption of diluent fluid, since there is no consumption of diluent fluid in the first stage, which may continue until the carbon content is 0.400 percent or even 0.300 percent.
  • Another advantage of the variants of the invention in which the oxidising fluid and the diluent fluid are not mixed prior to introduction but are introduced into each tuyere separately, is that they make the process very easy to operate and make it very easy to check the rates of flow of each fluid at any time, since each individual fluid remains uniform as it flows through each tuyere. For instance, if the diluent fluid is water vapour, there is no risk of the vapour condensing in the zone where it is mixed with cold oxygen, and so the actual water vapour flow through the tuyere can be controlled much more accurately than previously.
  • the first two Examples illustrate the use of separate double-feed tuyeres and the third and fourth Examples illustrate the use of separate triple feed tuyeres.
  • Blowing times are as follows:
  • Fluid consumptions for 20 tons of steel are as follows:
  • Oxygen 324 Nm3 i.e. 16.2 Nm3/t.
  • Argon 216 Nm3 i.e. 10.8 Nm3/t.
  • Fuel-oil 36 litres i.e. 1.8 litre/t.
  • Example 2 In this second example, a 20-ton converter is used having two separate double feed tuyeres. 1n each tuyere, the oxidising gas flow is at the centre and the fuel oil flow at the periphery.
  • the converter is charged with molten steel at 1,540C from an electric furnace, the steel composition being as follows:
  • the converter is charged with 20 tons of molten steel at 1,540C from an electric furnace, the steel composition being as follows:
  • Refining is carried out in three consecutive periods.
  • Vapour in 02. in Vapour volume ln stage 1 (i.e. period 1), pure oxygen is blown in both Nm3/mm- Nm3/mmthe primary and secondary circuits, and in stages 2 and m pcrigd 300,7 3 (periods 2 2nd 3) oxygen is blown in the primary cir- 2n: perm: 15 so curt and argon m the secondary circuit at rates of flow 9 5 given in the following table:
  • Argon Secondary Primary Secondary Argon +Oxygen circuit circuit Circuit Circuit lst period 0 15 I5 0% 2nd period l5 l5 0 50% 3rd period 21 9 (l 7071 A carefully controlled flow of domestic fuel oil flows at the periphery of each tuyere at a rate of l litre/minute for each tuyere, i.e., 2 litres/minute for both tuyeres together. Blowing times are as follows:
  • Oxygen 280 Nm3 i.c. l4 Nm3/t.
  • Water vapour I40 Nm3 i.e. 7 Nm3/t.
  • Fuel-oil 28 litres, i.e. l.4 litre/t.
  • the chromium loss in the slag is slight in these first two Examples of the invention, namely a 1.1 percent reduction of the bath content, corresponding to 6 percent of the total chromium content of the bath. Some of the lost chromium can, of course, be recovered by ferro-silicon reduction.
  • Example 3 The starting material in this Example is a 1 percent carbon metal.
  • a -ton converter is used having two separate triple feed tuyeres in which the flows-are as follows:
  • a carefully controlled flow of domestic fuel oil is provided at the periphery of each tuyere at a rate of 1 iitre/rninute/tuyere, i.c., 2 litres/minute for the two tuyeres together. Blowing times are as follows:
  • Fluid consumptions for 20 tons of metal are as follows:
  • Oxygen 333 Nm3 i.c. 16.6 Nm3/t Argon: 237 Nm3 i.c. 11.8 Nm3/t
  • Fuel oil 38 litres i.c. L9 litre/t.
  • Chromium loss in the slag is slight, namely a 1.2 percent reduction corresponding to 7 percent of the total chromium content of the bath. Some of this lost chromium can, of course, be recovered by ferro-silicon reduction.
  • Example 4 The starting material is a 6 percent carbon cast iron.
  • a process for refining an alloy steel containing chromium which comprises blowing fluids into the molten steel through at least one feed tuyere, each tuyere providing a first flow of an oxidising fluid, a second flow of a fluid for diluting the carbon monoxide in the bath, and a third peripheral flow, which is physically distinct and separate from the said first and second flows in the tuyere, of a hydro-carbon containing liquid, said third flow remaining in the liquid state until after leaving the tuyere.
  • diluent fluid supplied to the tuyere is a spray of water droplets in a vehicle gas.
  • a process according to claim 1, wherein the hydro-carbon containing liquid is fuel oil.
  • the carbon make-up liquid is an emulsion of a component selected from the group consisting of argon, water vapour and water droplets in fuel oil.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Carbon Steel Or Casting Steel Manufacturing (AREA)
US00247315A 1971-05-28 1972-04-25 Process for refining alloy steels containing chromium and including stainless steels Expired - Lifetime US3844768A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
FR7119463A FR2139642A1 (en) 1971-05-28 1971-05-28 Decarburising chrome steels by blowing with diluted carbon - monoxide through double/triple feed tuyeres
FR7127015A FR2146900A1 (en) 1971-07-23 1971-07-23 Decarburising chrome steels by blowing with diluted carbon - monoxide through double/triple feed tuyeres
FR7127016A FR2147795A1 (en) 1971-07-23 1971-07-23 Decarburising chrome steels by blowing with diluted carbon - monoxide through double/triple feed tuyeres
FR7206824A FR2173717A2 (en) 1972-02-29 1972-02-29 Decarburising chrome steels by blowing with diluted carbon - monoxide through double/triple feed tuyeres

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Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3982927A (en) * 1974-11-13 1976-09-28 Creusot-Loire Method of blowing to obtain a very low amount of carbon in chrome steels
US3985550A (en) * 1975-01-23 1976-10-12 United States Steel Corporation Method of producing low sulfur steel
US3990888A (en) * 1972-10-06 1976-11-09 Uddeholms Aktiebolag Decarburization of a metal melt
US4023676A (en) * 1976-09-20 1977-05-17 Armco Steel Corporation Lance structure and method for oxygen refining of molten metal
US4097028A (en) * 1975-02-06 1978-06-27 Klockner-Werke Ag Method of melting and apparatus therefor
US4138098A (en) * 1975-08-14 1979-02-06 Creusot-Loire Method of blowing smelting shaft furnaces and tuyeres used for said blowing
US4139370A (en) * 1972-01-13 1979-02-13 Gesellschaft Fur Elektrometallurgie Mbh Method of refining ferro-alloys
US4218049A (en) * 1978-07-17 1980-08-19 Pennsylvania Engineering Corporation Metallurgical vessel
US4401466A (en) * 1981-11-30 1983-08-30 Korf Technologies, Inc. Process for protection of nozzles and refractory lining of a vessel for refining molten metal
US4405366A (en) * 1979-06-20 1983-09-20 Klockner-Humboldt-Deutz Ag Method and device for generating a convective reaction system between a reaction agent and a molten bath
US4417723A (en) * 1981-10-22 1983-11-29 Kabushiki Kaisha Kobe Seiko Sho Tuyere for blowing gases into molten metal bath container
EP0182965A1 (de) * 1980-12-05 1986-06-04 Kortec Ag Verfahren zum Schutz der Düsen und der feuerfesten Auskleidung eines Gefässes zum Frischen einer Metallschmelze
US4657586A (en) * 1985-10-25 1987-04-14 Union Carbide Corporation Submerged combustion in molten materials
US4783219A (en) * 1985-11-13 1988-11-08 Nippon Kokan Kabushiki Kaisha Method for melting and reducing chrome ore
US4792352A (en) * 1986-01-20 1988-12-20 Nippon Kokan Kabushiki Kaisha Method for manufacturing steel through smelting reduction
US4891064A (en) * 1988-09-30 1990-01-02 Nippon Steel Corporation Method of melting cold material including iron
WO1994026937A1 (en) * 1993-05-14 1994-11-24 Mefos Stiftelsen För Metallurgisk Forskning A method of controlling the temperature of the bath in a converter
US5374297A (en) * 1993-01-05 1994-12-20 Steel Technology Corporation Lance for fuel and oxygen injection into smelting or refining furnace
US5435833A (en) * 1993-09-30 1995-07-25 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Process to convert non-ferrous metal such as copper or nickel by oxygen enrichment
US20110101576A1 (en) * 2007-08-29 2011-05-05 Posco Tuyere for Manufacturing Molten Iron and Method for Injecting Gas Using the Same

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3003865A (en) * 1959-09-10 1961-10-10 Cameron Iron Works Inc Decarburizing process for alloy steels containing chromium
US3046107A (en) * 1960-11-18 1962-07-24 Union Carbide Corp Decarburization process for highchromium steel
US3330645A (en) * 1962-08-07 1967-07-11 Air Liquide Method and article for the injection of fluids into hot molten metal
US3556773A (en) * 1966-09-26 1971-01-19 Steel Co Of Wales Ltd Refining of metals
US3706549A (en) * 1968-02-24 1972-12-19 Maximilianshuette Eisenwerk Method for refining pig-iron into steel
US3725041A (en) * 1970-09-25 1973-04-03 Allegheny Ludlum Ind Inc Deoxidizing metal

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3003865A (en) * 1959-09-10 1961-10-10 Cameron Iron Works Inc Decarburizing process for alloy steels containing chromium
US3046107A (en) * 1960-11-18 1962-07-24 Union Carbide Corp Decarburization process for highchromium steel
US3330645A (en) * 1962-08-07 1967-07-11 Air Liquide Method and article for the injection of fluids into hot molten metal
US3556773A (en) * 1966-09-26 1971-01-19 Steel Co Of Wales Ltd Refining of metals
US3706549A (en) * 1968-02-24 1972-12-19 Maximilianshuette Eisenwerk Method for refining pig-iron into steel
US3725041A (en) * 1970-09-25 1973-04-03 Allegheny Ludlum Ind Inc Deoxidizing metal

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4139370A (en) * 1972-01-13 1979-02-13 Gesellschaft Fur Elektrometallurgie Mbh Method of refining ferro-alloys
US3990888A (en) * 1972-10-06 1976-11-09 Uddeholms Aktiebolag Decarburization of a metal melt
US3982927A (en) * 1974-11-13 1976-09-28 Creusot-Loire Method of blowing to obtain a very low amount of carbon in chrome steels
US3985550A (en) * 1975-01-23 1976-10-12 United States Steel Corporation Method of producing low sulfur steel
US4097028A (en) * 1975-02-06 1978-06-27 Klockner-Werke Ag Method of melting and apparatus therefor
US4138098A (en) * 1975-08-14 1979-02-06 Creusot-Loire Method of blowing smelting shaft furnaces and tuyeres used for said blowing
US4023676A (en) * 1976-09-20 1977-05-17 Armco Steel Corporation Lance structure and method for oxygen refining of molten metal
US4218049A (en) * 1978-07-17 1980-08-19 Pennsylvania Engineering Corporation Metallurgical vessel
US4494736A (en) * 1979-06-20 1985-01-22 Klockner-Humboldt-Deutz Ag Device for generating a convective reaction system between a reaction agent and a molten bath
US4405366A (en) * 1979-06-20 1983-09-20 Klockner-Humboldt-Deutz Ag Method and device for generating a convective reaction system between a reaction agent and a molten bath
EP0182965A1 (de) * 1980-12-05 1986-06-04 Kortec Ag Verfahren zum Schutz der Düsen und der feuerfesten Auskleidung eines Gefässes zum Frischen einer Metallschmelze
US4417723A (en) * 1981-10-22 1983-11-29 Kabushiki Kaisha Kobe Seiko Sho Tuyere for blowing gases into molten metal bath container
US4401466A (en) * 1981-11-30 1983-08-30 Korf Technologies, Inc. Process for protection of nozzles and refractory lining of a vessel for refining molten metal
US4657586A (en) * 1985-10-25 1987-04-14 Union Carbide Corporation Submerged combustion in molten materials
US4783219A (en) * 1985-11-13 1988-11-08 Nippon Kokan Kabushiki Kaisha Method for melting and reducing chrome ore
EP0222397A3 (en) * 1985-11-13 1989-06-07 Nippon Kokan Kabushiki Kaisha Method for melting and reducing chrome ore method for melting and reducing chrome ore
US4792352A (en) * 1986-01-20 1988-12-20 Nippon Kokan Kabushiki Kaisha Method for manufacturing steel through smelting reduction
US4891064A (en) * 1988-09-30 1990-01-02 Nippon Steel Corporation Method of melting cold material including iron
US5374297A (en) * 1993-01-05 1994-12-20 Steel Technology Corporation Lance for fuel and oxygen injection into smelting or refining furnace
WO1994026937A1 (en) * 1993-05-14 1994-11-24 Mefos Stiftelsen För Metallurgisk Forskning A method of controlling the temperature of the bath in a converter
US5435833A (en) * 1993-09-30 1995-07-25 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Process to convert non-ferrous metal such as copper or nickel by oxygen enrichment
US20110101576A1 (en) * 2007-08-29 2011-05-05 Posco Tuyere for Manufacturing Molten Iron and Method for Injecting Gas Using the Same

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DE2215435A1 (de) 1973-01-04
GB1354853A (en) 1974-06-05
LU65052A1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1972-07-11
IT954593B (it) 1973-09-15
AU467460B2 (en) 1975-12-04
CA971755A (en) 1975-07-29
AU4173372A (en) 1973-11-08
JPS5147133B1 (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1976-12-13
JPS50110923A (GUID-C5D7CC26-194C-43D0-91A1-9AE8C70A9BFF.html) 1975-09-01
BE781241A (fr) 1972-07-17
DE2215435B2 (de) 1973-07-05

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