ZA200302646B - Method for producing stainless steel, in particular highgrade steels containing chromium and chromium-nickel. - Google Patents
Method for producing stainless steel, in particular highgrade steels containing chromium and chromium-nickel. Download PDFInfo
- Publication number
- ZA200302646B ZA200302646B ZA200302646A ZA200302646A ZA200302646B ZA 200302646 B ZA200302646 B ZA 200302646B ZA 200302646 A ZA200302646 A ZA 200302646A ZA 200302646 A ZA200302646 A ZA 200302646A ZA 200302646 B ZA200302646 B ZA 200302646B
- Authority
- ZA
- South Africa
- Prior art keywords
- nozzles
- blowing
- melt
- lances
- treatment
- Prior art date
Links
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 title claims description 23
- 229910052804 chromium Inorganic materials 0.000 title claims description 23
- 239000011651 chromium Substances 0.000 title claims description 23
- 229910000831 Steel Inorganic materials 0.000 title claims description 8
- 239000010959 steel Substances 0.000 title claims description 8
- VNNRSPGTAMTISX-UHFFFAOYSA-N chromium nickel Chemical compound [Cr].[Ni] VNNRSPGTAMTISX-UHFFFAOYSA-N 0.000 title claims description 5
- 238000004519 manufacturing process Methods 0.000 title claims description 4
- 229910001220 stainless steel Inorganic materials 0.000 title claims description 4
- 239000010935 stainless steel Substances 0.000 title 1
- 238000000034 method Methods 0.000 claims description 51
- 238000007664 blowing Methods 0.000 claims description 38
- 239000002893 slag Substances 0.000 claims description 35
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 25
- 239000000155 melt Substances 0.000 claims description 25
- 239000001301 oxygen Substances 0.000 claims description 25
- 229910052760 oxygen Inorganic materials 0.000 claims description 25
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 21
- 229910052799 carbon Inorganic materials 0.000 claims description 21
- 238000002844 melting Methods 0.000 claims description 20
- 230000008018 melting Effects 0.000 claims description 20
- 229910052751 metal Inorganic materials 0.000 claims description 12
- 239000002184 metal Substances 0.000 claims description 12
- 238000010309 melting process Methods 0.000 claims description 11
- 239000000203 mixture Substances 0.000 claims description 11
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 10
- 229910052710 silicon Inorganic materials 0.000 claims description 10
- 239000010703 silicon Substances 0.000 claims description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 8
- 239000003795 chemical substances by application Substances 0.000 claims description 8
- 229910045601 alloy Inorganic materials 0.000 claims description 7
- 239000000956 alloy Substances 0.000 claims description 7
- 239000011449 brick Substances 0.000 claims description 7
- 238000010079 rubber tapping Methods 0.000 claims description 7
- 238000002347 injection Methods 0.000 claims description 6
- 239000007924 injection Substances 0.000 claims description 6
- 230000002349 favourable effect Effects 0.000 claims description 4
- 239000011261 inert gas Substances 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 238000002156 mixing Methods 0.000 claims description 4
- 239000002994 raw material Substances 0.000 claims description 4
- 239000000969 carrier Substances 0.000 claims description 3
- 238000005266 casting Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 238000009434 installation Methods 0.000 claims description 3
- 239000002826 coolant Substances 0.000 claims description 2
- 238000000265 homogenisation Methods 0.000 claims description 2
- 238000011946 reduction process Methods 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims 2
- 239000007787 solid Substances 0.000 claims 2
- 238000010314 arc-melting process Methods 0.000 claims 1
- 239000007789 gas Substances 0.000 description 4
- 239000004411 aluminium Substances 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 238000007670 refining Methods 0.000 description 2
- 229910002555 FeNi Inorganic materials 0.000 description 1
- 229910000604 Ferrochrome Inorganic materials 0.000 description 1
- 229910000519 Ferrosilicon Inorganic materials 0.000 description 1
- 229910000805 Pig iron Inorganic materials 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- 229910000423 chromium oxide Inorganic materials 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000010436 fluorite Substances 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000011819 refractory material Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 239000002912 waste gas Substances 0.000 description 1
Classifications
-
- 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
-
- 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
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/52—Manufacture of steel in electric furnaces
- C21C5/5264—Manufacture of alloyed steels including ferro-alloys
-
- 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
- C21C5/52—Manufacture of steel in electric furnaces
- C21C5/5252—Manufacture of steel in electric furnaces in an electrically heated multi-chamber furnace, a combination of electric furnaces or an electric furnace arranged for associated working with a non electric furnace
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Description
DrG REF: 40726
Method for producing stainless steels, in particular high grade steels containing chromium and chromium-nickel.
The invention relates to a method according to the upper part of claim 1 or the claim 2.
Multi-stage processes in a melting arrangement including at least two vessels are known for producing chromium or chromium-nickel containing high grade steels. Depending on the particular procedural technology thereby a decatbonisation down to carbon contents of below 0,3 % is performed. A high energy consumption is always necessary and temperature losses are unavoidable.
Such a method is known from the DE 196 21 143. The method described here is performed in a melting device, which includes at least two vessels.
Both vessels are operated parallel, whereby in each vessel there are applied alternately either electrodes for melting the charge or for blow lances for top blowing and/or injecting oxygen and oxygen mixtures. The vessels also serve initially as melting and thereafter as refining installation. After the blowing the slag is reduced by means of reduction agents, such as for example ferrosilicon, aluminium or secondary aluminium with the addition of slag formers, such as chalk and fluorspar for recovering oxidised chromium, and subsequently is tapped.
It is an object of the invention to make such a process more economic.
This object is solved by means of the method steps stated in the characterising part of claim 1 or 2. Suitable embodiments of the process are contained in the subsidiary claims.
The cote of the invention is the reversible treatment of unreduced converter slags in electro arc furnace operations. In difference to the known methods, in which the reduction of the high chromium containing slags and therewith the recovery of the metallic chromium is performed in a method step downstream of melting and oxygen injection and separated therefrom, the reduction now is performed in the vessel simultaneously with a renewed melting procedure of a new charge under retention of the slag of the previous blowing process. In this manner a method step, namely the subsequent reduction of the slag, is saved and also the chromium containing slag is not withdrawn from the system. Overall the method is performed simpler and mote economical.
In detail the following steps are performed: oo a) Heating of high chromium containing slag in the first treatment step together with the melting in of the added charge and this being by means of electrical energy from the electro arc, b) Reduction of the high chromium containing slag during the melting process with the silicon and catbon at favourable thermodynamic conditions of the arc, after the melt has reached a temperature level of a minimum of 1.490°C, with subsequent removal of the slag,
¢) Treatment of the melt in the same vessel by means of a blowing process, whereby by blowing of oxygen or oxygen mixture through top lances, side lances, side below bath nozzles, side nozzles, floor nozzles or rinsing bricks, respectively individually or combined, the melt is decarbonized down to a carbon value of less than < 0,9 %, preferaby < 0,4 % and is heated to a tapping temperature of 1.620 up to 1.720°C, d) Mixing of the melt with an inett gas, which is introduced by way of top lances, side lances, side under bath nozzles, side nozzles, floor nozzles or rinsing bricks, respectively individually or in combination, e) Injection/top blowing of alloy agents, slag formers, reduction agents, metal-oxide-metal containing dusts or mixtures by way of top lances, side lances, side under bath nozzles, side nozzles, floor nozzles or rinsing bricks, respectively individually or in combination, f) subsequent tapping of the melt, whereby the unreduced high chromium containing slag of the blowing process remains in the treatment vessel and is reduced in a new cycle of the electro furnace melting process according to step a).
The suggested method basically can take place in a single metallurgical vessel. For accelerating the tapping times it is suggested according to claim 2, that the method is performed in a melting device with two, or alternately operated metallurgical vessels. Thus parallel next to the decarbonising blowing of the charge in the first treatment process, the melting process of a second charge including the reduction process of the slag is performed in the second treatment vessel.
The melting procedure can also be performed in another way than electrically by means of light atcs, whereby care has to be taken that the favourable thermodynamic conditions for reduction of the slags are retained.
Preferably the blowing of oxygen or oxygen mixtures is performed in the form of top blowing and/ or side blowing. Inert gasses can be injected for improved mixing and homogenization of the melt simultaneously to the oxygen blowing process.
The melt is decarbonised during a blowing time of the oxygen of 20 to 40 minutes to an end carbon content of < 0,9 %, preferably < 0,4 %.
During the oxygen blowing cooling agents, for example in the form of Ni,
FeNi, ferrochromium, scrap iron or other iron containing metallic raw material, such as raw pig iron, DRI or alloy agents ate added, in order to reach the target temperature.
According to a preferred method step the blowing process is terminated at a carbon content of more or less 0,9 %, preferably equal to or less than 0,4 %o, and a temperature of above 1.680°C, and the molten metal is tapped into a ladle. In accordance with the invention the slag remains in the vessel, so as to be reduced subsequently during the renewed melting procedure. Separate hereto during the further treatment development, the molten metal is brought to the required end carbon content of < 0,1 % by : means of a secondary metallurgical treatment, preferably vacuum degassification. This also has the advantage that the refractory material of the vessel, which is stressed greatly during a blowing process down to the low carbon content, is taken care of.
In accordance with the invention the high chromium containing slag can be reduced together with the silicon or carbon containing alloy carriers in 5 the charge. According to a particular preferred variation of the method it is suggested that additionally carbon and, if necessary, silicon is added.
The chromium oxide contained in the high chromium containing slag is reduced by the carbon and the silicon directly to metallic chromium.
During the melting in of the charge by way of top lances, side, below bath nozzles, side nozzles, floor nozzles or rinsing bricks, respectively individually or in combination, oxygen or oxygen mixtures are added for improved silicon and catbon oxidation.
Further details and advantages of the invention result from the following description, in which the method in accordance with the invention is 15s explained in more detail in the represented drawing of the embodiment of a melting device, here with two metallurgical vessels. Therewith, in addition to the abovementioned combination of characteristics, also characteristics separately or in other combination are relevant to the invention. In this connection the single figure shows the side view of a melting device with two treatment vessels.
The melting device 1 consists of two treatment vessels 2, 3 in which alternately an electro-arc furnace process (1) and a blowing process (11) are operated. There is shown in the left treatment vessel 2 the operational condition of the melting in by means of electric arcs, in the right treatment vessel 3 the operational condition of the refining or oxygen blowing for reducing the carbon content of the melt.
For oxygen injection a lance 4 is attached to a lance carrying arm 5, which is led co-axially to the vessel main axis through a waste gas exhaust 6 and the lid opening 7 of a pivotable lid 8 of the right treatment vessel 3 into the inner space of the vessel upper part 9. The mouth 10 of the gas exhaust 6 abuts against the lid opening 7 of the lid 8. The upper part 9 and the lower part 11 together form the furnace vessel 3. The discharge gas exhaust 6 is pivotable relative to the neighbouring treatment vessel 2 by means of a rotational arrangement 12. The lower part 11 has a tap opening 13, here the floor tap, for the molten metal, whereas the chromium containing slag remains in the vessel.
In the floor ot in the wall of the vessel there are respectively individual or - combined floor nozzles 22, rinsing stones, side below bath nozzles, side nozzles 20 and/or side lances 21 through which oxygen, inert gas or gas mixtures are blown.
The treatment vessel 2, shown on the left, has a pivotable electrode arm 14, at which in the present case three electrodes 15a, b, c are attached, which are led through the lid 16 of the left treatment vessel 2, which closes the lid opening 17.
After the molten metal 18 has been tapped through the tap opening 13 in the treatment vessel, a new melting procedure is commenced. The tapped melt is guided to a steel casting plant or a secondary metallurgical treatment plant (not shown). The non-tapped slag 19, remaining in the vessel is charged, whereby the chatge contains in particular carbon and silicon containing raw materials, and the overall content subsequently is molten. During the melting process the high chromium containing slag 1s reduced, after the melt has reached a temperature level of a minimum of 1.490°C. After reaching a temperature level of preferably a minimum of 1.550°C the slag is removed and the melt is subjected to a blowing - process, whereby the melt is decarbonised to a carbon content of < 0,9 %, preferably < 0,4 % and to a tap temperature of 1.620 to 1.720°C. For this the electrode arm 14 is pivoted out and the oxygen lance 4 is pivoted in.
Subsequently only the molten metal is tapped. The lance 4 is drawn out and the procedure is started anew. In the neighbouring vessel this procedure takes place in time shifted relationships.
Claims (7)
1. Method for producing stainless steels, in particular high grade steels containing chromium and chromium nickel, in a melting device containing a metallurgical vessel for supplying a steel casting installation, whereby an electro-arc furnace process and a blow process are operated in the vessel, and whereby in a first of these treatment processes, in which the electro-arc furnace melting process is performed, a charge, substantially consisting of solid and/or liquid raw iron and raw materials, in particular of metal scrap and partially carbon and silicon containing alloy carriers, is molten and the melt subsequently is refined, charactetized thereby that reversive treatment of unreduced slags after the blowing process in the electro arc furnace operation by way of the following steps: a) Heating of high chromium containing slag in the first treatment step together with the melting in of the added charge, b) ~~ Reduction of the high chromium containing slag during the melting process with the silicon and carbon at favourable thermodynamic conditions of the arc, after the melt has reached a temperature value of a minimum of 1.490°C, with subsequent removal of the slag, ¢) Treatment of the melt in the same vessel by means of a blowing process, whereby by blowing of oxygen or oxygen mixture through top lances, side lances, side below bath nozzles, side nozzles, floor nozzles or rinsing bricks, respectively individually or combined, the melt is decarbonized down to a carbon value of less than < 0,9 % and is heated to a tapping temperature of 1.620 up to 1.720°C, d) Mixing of the melt with an inert gas, which is introduced by way of top lances, side lances, side under bath nozzles, side’ nozzles, floor nozzles or rinsing stones, respectively individually or in combination, e) Injection/top blowing of alloy agents, slag formers, reduction agents, metal-oxide-metal containing dusts or mixtures by way of top lances, side lances, side under bath nozzles, side nozzles, floor nozzles or rinsing stones, respectively individually or in combination, f) subsequent tapping of the melt, whereby the unreduced high chromium containing slag of the blowing process remains in the treatment vessel and is reduced in a new cycle of the electro furnace melting process according to step a).
2. Method for producing stainless steels, in particular chromium and chromium nickel containing steels, in a melting device (1), including at least two vessels (2, 3) for supplying a steel casting installation, whereby in both vessels (2 and 3) alternately an electro-arc furnace process (1) and a blowing process (11) are operated, and whereby in a first of these treatment steps, in which the electro-arc melting process is performed, a charge, substandally consisting of solid and/or liquid raw iron and raw material, in particular of metal scrap and alloy carriers containing, partially carbon and silicon, is molten, and the melt is refined, and whereby simultaneously in addition to the decatbonising blowing of the charge in the first treatment vessel (2) the melting process is performed in a second charge in the second treatment vessel (3), characterized thereby that reversive treatment of unreduced slag (19) after the blowing process in the electro arc furnace operation by way of the following steps:
a) Heating of high chromium containing slag (19) in the first treatment step together with the melting in of the added charge,
: b) Reduction of the high chromium containing slag during the melting process with the silicon and carbon at favourable thermodynamic conditions of the arc, after the melt has reached a temperature value of a minimum of 1.490°C, with subsequent removal of the slag,
c) Treatment of the melt in the same vessel by means of a blowing process, whereby by blowing of oxygen or oxygen mixture through top lances, side lances, side below bath nozzles, side nozzles, floor nozzles or rinsing bricks,
respectively individually or combined, the melt is decarbonized down to a carbon value of less than < 0,9 %, and is heated to a tapping temperature of 1.620 up to 1.720°C,
d) Mixing of the melt with an inert gas, which is introduced by way of top lances, side lances, side under bath nozzles, side nozzles, floor nozzles or rinsing stones, respectively individually ot in combination, ¢) Injection/top blowing of alloy agents, slag formers, reduction agents, metal-oxide-metal containing dusts or mixtures by way of top lances, side lances, side under bath nozzles, side nozzles, floor nozzles or rinsing stones, respectively individually or in combination, f) subsequent tapping of the melt (18), whereby the unreduced high chromium containing slag (19) of the blowing process remains in the treatment vessel and is reduced in a new cycle of the electro furnace melting process according to step a), and g) whereby simultaneously next to the decarbonising blowing of the charge in the first treatment process, the melting process of a second charge including the reduction process of the slag is performed in the second treatment vessel.
3. Method according to claim 1 or 2, characterized thereby that blowing of oxygen or oxygen mixtures takes place through top lances, side lances, side below bath nozzles, side nozzles, floor nozzles or rinsing stones, respectively individually or in combination, in the form of top blowing and/or injection.
4. Method according to one of the claims 1, 2 or 3, characterized thereby that, for purposes of the admixing or homogenisation of the melt simultaneously to the oxygen blowing process, the inert gases are Injected through top lances, side lances, side below bath nozzles,
side nozzles, floor nozzles or rinsing bricks, respectively individually or in combination.
5. Method according to one of the claims 1 to 4, characterized thereby that in a blowing period of the oxygen of 20 to 40 minutes the melt is decarbonised to an end carbon content of < 0,9 %.
6. Method according to one of the claims 1 to 5, characterized thereby that cooling agent is added during the oxygen blowing.
7. Method according to one of the claims 1 to 6, characterized thereby that the blowing process is terminated at a carbon content of < 0,9 % and a temperature above 1.680°C, that the metal melt (18) is discharged into a pan and the slag (19) remains in the vessel, and that in further treatment development the molten metal is brought to the desired end carbon content of < 0,1 % by means of a secondary ~~ metallurgical treatment, preferably vacuum degassification. t:\files\ 26\40726\ 40726translation.doc :
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE10051803 | 2000-10-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| ZA200302646B true ZA200302646B (en) | 2004-03-08 |
Family
ID=7660309
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| ZA200302646A ZA200302646B (en) | 2000-10-18 | 2003-04-04 | Method for producing stainless steel, in particular highgrade steels containing chromium and chromium-nickel. |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE10115779A1 (en) |
| ZA (1) | ZA200302646B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10227031A1 (en) * | 2002-06-17 | 2004-01-08 | Sms Demag Ag | Process and production plant for producing products from carbon steel or from stainless steel |
| EP3762514B1 (en) * | 2018-03-06 | 2024-08-14 | SMS group GmbH | Smelting assembly for the production of steel |
| DE102021214227A1 (en) | 2021-12-13 | 2023-06-15 | Sms Group Gmbh | Melting unit for steel production with a tapping weight between 60 t and 350 t |
-
2001
- 2001-03-29 DE DE10115779A patent/DE10115779A1/en not_active Withdrawn
-
2003
- 2003-04-04 ZA ZA200302646A patent/ZA200302646B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| DE10115779A1 (en) | 2002-04-25 |
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