US2937084A - Process for production of high-grade cast-iron - Google Patents
Process for production of high-grade cast-iron Download PDFInfo
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- US2937084A US2937084A US696922A US69692257A US2937084A US 2937084 A US2937084 A US 2937084A US 696922 A US696922 A US 696922A US 69692257 A US69692257 A US 69692257A US 2937084 A US2937084 A US 2937084A
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- US
- United States
- Prior art keywords
- bath
- iron
- silicon
- blowing
- oxygen
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- 238000000034 method Methods 0.000 title claims description 11
- 238000004519 manufacturing process Methods 0.000 title claims description 6
- 229910001018 Cast iron Inorganic materials 0.000 title description 11
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 35
- 229910052710 silicon Inorganic materials 0.000 claims description 22
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 21
- 239000010703 silicon Substances 0.000 claims description 21
- 229910052742 iron Inorganic materials 0.000 claims description 18
- 238000007664 blowing Methods 0.000 claims description 17
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 14
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 13
- 229910052760 oxygen Inorganic materials 0.000 claims description 13
- 239000001301 oxygen Substances 0.000 claims description 13
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 12
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical group [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 10
- 239000000463 material Substances 0.000 claims description 7
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 6
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 6
- 229910001141 Ductile iron Inorganic materials 0.000 claims description 5
- 239000000292 calcium oxide Substances 0.000 claims description 5
- 239000002253 acid Substances 0.000 claims description 4
- 230000015572 biosynthetic process Effects 0.000 claims description 3
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 3
- BHEPBYXIRTUNPN-UHFFFAOYSA-N hydridophosphorus(.) (triplet) Chemical compound [PH] BHEPBYXIRTUNPN-UHFFFAOYSA-N 0.000 claims description 3
- 230000008018 melting Effects 0.000 claims description 2
- 238000002844 melting Methods 0.000 claims description 2
- 238000007711 solidification Methods 0.000 claims description 2
- 230000008023 solidification Effects 0.000 claims description 2
- 239000000126 substance Substances 0.000 claims description 2
- 229910052799 carbon Inorganic materials 0.000 description 7
- 239000002893 slag Substances 0.000 description 7
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 6
- 239000011777 magnesium Substances 0.000 description 6
- 229910052749 magnesium Inorganic materials 0.000 description 6
- 235000017550 sodium carbonate Nutrition 0.000 description 5
- 229940001593 sodium carbonate Drugs 0.000 description 5
- 235000012255 calcium oxide Nutrition 0.000 description 4
- 229960005191 ferric oxide Drugs 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 235000013980 iron oxide Nutrition 0.000 description 4
- 229910052698 phosphorus Inorganic materials 0.000 description 4
- 239000005864 Sulphur Substances 0.000 description 3
- 238000007792 addition Methods 0.000 description 3
- 229910045601 alloy Inorganic materials 0.000 description 3
- 239000000956 alloy Substances 0.000 description 3
- 239000000428 dust Substances 0.000 description 3
- 239000000155 melt Substances 0.000 description 3
- 229910001060 Gray iron Inorganic materials 0.000 description 2
- 229910000861 Mg alloy Inorganic materials 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 229940087373 calcium oxide Drugs 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- 239000005997 Calcium carbide Substances 0.000 description 1
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 229910017639 MgSi Inorganic materials 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 150000001721 carbon Chemical class 0.000 description 1
- 238000005255 carburizing Methods 0.000 description 1
- 239000002801 charged material Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical group 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- CLZWAWBPWVRRGI-UHFFFAOYSA-N tert-butyl 2-[2-[2-[2-[bis[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]amino]-5-bromophenoxy]ethoxy]-4-methyl-n-[2-[(2-methylpropan-2-yl)oxy]-2-oxoethyl]anilino]acetate Chemical compound CC1=CC=C(N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)C(OCCOC=2C(=CC=C(Br)C=2)N(CC(=O)OC(C)(C)C)CC(=O)OC(C)(C)C)=C1 CLZWAWBPWVRRGI-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/08—Making cast-iron alloys
Definitions
- high-grade cast-iron hasubeen produced .by remelting soft-iron or steel scrapin electric are or high-frequency furnaces, followed by carburizing. If, however, an acid cupola furnace should be used for the production of a high-grade I cast-iron, such as spheroidal graphite cast-iron, a selected special charge free of disturbing elements and having a low silicon contentis absolutely necessary. This requirement is always emphasized by the licensors of processes for the production of spheroidal or nodular graphite castiron.
- a preferred embodiment of the invention enables also a dephosphorizing of the charge.
- the dephosphorization proceeds according to the which are inequilibrium with each other.
- the equilibrium constant is known to be proportional to the;FeO and CaO contents of the slag, and has a negative temperature coefiicient so that the dephosphorization will be the-better the higher are the FeO and C210 content or the basicity of the slag and the lower is the reaction temperature,
- the dephosphorization of molten cupola iron is normally disturbed, however, .byv the silicon and carbon contents.
- the slagged silicon which is available in the form of SiO;;, may cause a rephosphorization by,
- an effective dephosphorization and at the same time a reduction of the-sulphur content is effected by adding aniron oxide carrier together with a fine grained material containing Ca0 and Na CO during the blowing of oxygen to the ,bath.
- ironoxide carrier may preferably consistof'the dust obtained in knownsurface blowing processes 'used for making steelfrom crude iron. Becauseit is important that theadditions should be as finely divided as possible, in
- the iron oxide carrier as well as the basic additions into the bath with the aid of the blowing gas itself.
- Part of the sulphur may be'rendered harmless by a pretreatment of the spout iron with sodium carbonate, magnesium or calcium carbide before oxygen is blown thereon.
- a cupola iron charge was composed of the following starting materials:
- the oxidizing treatment of the charge of cupola iron is desirably effected by blowing technically pure oxygen onto the surface of the bath of molten iron under such blowing conditions that the silicon content is reduced to less than 1%, preferably to about 0.5% and the simultaneous oxidation of carbon does not exceed 0.20%
- an oxygen blowing tube having a diameter of about 10 mm. may be used and approximately 10 cubic metres of oxygen per ton of the bath may be supplied to the bath under a pressure of 2-10 kg./sq. cm. above atmospheric pressure, depending on the amount of the charge.
- the temperature on the surface of the bath will amount to about 1500 deg. C. and the removal of silicon and of the disturbing elements will be effected within a few minutes, the temperature of the bath increasing by about 150 deg. C.
- the resulting spout iron had a temperature of 1330 deg. C., measured with a pyropto instrument. It was tapped into a ladle and treated with a small amount of sodium-carbonate for preliminary desulphurization. A small amount of Elektron (a known magnesium alloy) may be used instead of the sodium carbonate. Then lime was added in small lumps to the bath and an oxygen jet was blown onto the surface of the bath under a pressure of 5 kg./ sq. cm. above atmospheric pressure from a nozzle having a diameterof 10 mm.
- the cast-iron produced according to the invention has no spheroidal graphite structure it has greatly improved strength properties and a lower mass influence compared to ordinary grey cast-iron or to iron which has been superheated in the electric furnace.
- Typical characteristic values obtained With a specimen 30 mm. in diameter and consisting of iron containing 3.3% C, 2.2%.Si and.0.60% Mn are indicated hereinafter.
- the first column contains the values for ordinary grey cast-iron
- the second column contains the values for cast-iron which has been superheated in the electric furnace
- the third column indicates the values for oxygentreated cast-iron.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Description
United States Patent PROCESS FORPRODUCTION OF HIGH-GRADE CAST-IRON Fritz Klepp and Richard Werner, Liezen, Austria, assignors to Vereinigte Osterreichische Eisenuntl Stahlwerke Aktiengesellschaft, Linz, Austria, a company of Austria .No Drawing. Application November 18, 1957 Serial No. 696,922
2 Claims. (Cl. 75-130) be present and the silicon content of the starting material should be less than 1%. If the silicon content is higher, a subsequent addition of substances which cause the formation of .thespherical graphite structure and are usually employed in form of alloys with silicon may increase the silicon content to such a degree as to cause losses in quality, 7
In order to fulfill the requirements set forth, high-grade cast-iron hasubeen produced .by remelting soft-iron or steel scrapin electric are or high-frequency furnaces, followed by carburizing. If, however, an acid cupola furnace should be used for the production of a high-grade I cast-iron, such as spheroidal graphite cast-iron, a selected special charge free of disturbing elements and having a low silicon contentis absolutely necessary. This requirement is always emphasized by the licensors of processes for the production of spheroidal or nodular graphite castiron.
It is an object of the present invention to improve the economic efiiciency of the production of high-grade castiron. More particularly, it is an object of the invention to enable the production of high-grade cast-iron from a normal charge in the acid cupola furnace, without need for a special selection of the charged materials as regards their silicon content and any content of disturbing elements.
According to the invention this problem is solved in Whereas it is generally impossible to remove phosphorus from normal cast-iron, a preferred embodiment of the invention enables also a dephosphorizing of the charge. The dephosphorization proceeds according to the which are inequilibrium with each other. The equilibrium constant is known to be proportional to the;FeO and CaO contents of the slag, and has a negative temperature coefiicient so that the dephosphorization will be the-better the higher are the FeO and C210 content or the basicity of the slag and the lower is the reaction temperature,
provided that the temperature is sufficient for producing a reactive slag. The dephosphorization of molten cupola iron is normally disturbed, however, .byv the silicon and carbon contents. The slagged silicon, which is available in the form of SiO;;, may cause a rephosphorization by,
a decomposition of phosphates which have been formed. This is highly undesirable. On the other hand, it is known from surface blowing steel-making processes thata dephosphorization will not occur until the carbon content is reduced below 2% because the slag will be sufliciently reactive only at this time. It is obvious that this carbon content is too low for cast-iron because'it would require, a subsequent carburization. For this reason grey. cast-y iron has not been dephosphorized in most cases.
According to theinvention an effective dephosphorization and at the same time a reduction of the-sulphur content, is effected by adding aniron oxide carrier together with a fine grained material containing Ca0 and Na CO during the blowing of oxygen to the ,bath. The
ironoxide carrier may preferably consistof'the dust obtained in knownsurface blowing processes 'used for making steelfrom crude iron. Becauseit is important that theadditions should be as finely divided as possible, in
order to achieve a quick reaction, it is preferable to introduce the iron oxide carrier as well as the basic additions into the bath with the aid of the blowing gas itself. Part of the sulphur may be'rendered harmless by a pretreatment of the spout iron with sodium carbonate, magnesium or calcium carbide before oxygen is blown thereon.
As an example for the practice of the process according'to the invention a cupola iron charge was composed of the following starting materials:
5 40% scrap of spheroidal graphite caSt-iron containing that iron which has been made by melting a normal charge in the acid cupola furnace is treated by blowing it with oxygen or oxygen-enriched gas, preferably in the presence of a basic slag, for reducing the silicon content, by which treatment the temperature of the bath is increased and the disturbing elements which are detrimental for a subsequent processing to spheroidal graphite cast-iron are also removed. g v w The oxidizing treatment of the charge of cupola iron is desirably effected by blowing technically pure oxygen onto the surface of the bath of molten iron under such blowing conditions that the silicon content is reduced to less than 1%, preferably to about 0.5% and the simultaneous oxidation of carbon does not exceed 0.20% For instance, an oxygen blowing tube having a diameter of about 10 mm. may be used and approximately 10 cubic metres of oxygen per ton of the bath may be supplied to the bath under a pressure of 2-10 kg./sq. cm. above atmospheric pressure, depending on the amount of the charge. In that case the temperature on the surface of the bath will amount to about 1500 deg. C. and the removal of silicon and of the disturbing elements will be effected within a few minutes, the temperature of the bath increasing by about 150 deg. C.
15% iron mould breakage containing 0.12% P and A hot blast was employed and the resulting spout iron contained 3.60% C, 0.07% P and 1.65% Si.
The resulting spout iron had a temperature of 1330 deg. C., measured with a pyropto instrument. It was tapped into a ladle and treated with a small amount of sodium-carbonate for preliminary desulphurization. A small amount of Elektron (a known magnesium alloy) may be used instead of the sodium carbonate. Then lime was added in small lumps to the bath and an oxygen jet was blown onto the surface of the bath under a pressure of 5 kg./ sq. cm. above atmospheric pressure from a nozzle having a diameterof 10 mm. After a blowing period of four minutes an injector valve was opened whereby a powder supply container, which contained a mixture of dust from surface blowing steelrnaking processes and dust slag which contained CaO and Na CO was connected to the oxygen supply conduit; the blowing was continued.
Patented May '17, 1960- After an additional blowing period of 3 minutes the blowing gaswas shut ofi and the bath was slagged off. At this time the bath had a carbon content of 3.42%, a phosphorus content of 0.055% and-a silicon content of 0.52%. The temperature measured with the Pyropto was 1450 deg. C." The iron having this composition was suitable low specific gravity and the high vapour pressure of the" magnesium at the temperatures of the molten iron. Various methods, such as the immersion-bell method or the pressure-ladle method, have been proposed for introducing pure magnesium. In view of the difficulty involved in maintaining thetemperature and for safety reasons, however, it is always preferred to introduce magnesium into the bath in the form of silicon-containing master alloyspsuch as SiMgFe, whereby the vapour pressure is reduced. These alloys, however, have the disadvantage of introducing a larger amount of silicon into the bath, which adversely affects the toughness of the cast material. As has already been mentioned, these difficulties are eliminated accordingto the invention by reducing the silicon content of the bath to a value which permits the use of silicon-containing magnesium alloys for producing the spherical graphite structure or the addition of inoculating silicon without disturbing the toughness properties. Surprisingly it has been found that independently of the method employed for the introduction ofmagnesium the magnesiumcontent or output obtained with 'melts which had previously-been treated according to the invention with oxygen was higher than with melts which came froman' electric furnace. 'Whereas the spheroidal graphite cast-iron from the-electric furnace, containing about 0.02% S, has a;final magnesium content of 0.04-0.06 if the usual amount of MgSi alloy has been added, a magnesium content of 0.09% was achieved under the same temperature conditions with an iron which had been blown with oxygen although the melt had an initial sulphur content of 0.04%.
Even'if the cast-iron produced according to the invention has no spheroidal graphite structure it has greatly improved strength properties and a lower mass influence compared to ordinary grey cast-iron or to iron which has been superheated in the electric furnace.
Typical characteristic values obtained With a specimen 30 mm. in diameter and consisting of iron containing 3.3% C, 2.2%.Si and.0.60% Mn are indicated hereinafter. The first column contains the values for ordinary grey cast-iron, the second column contains the values for cast-iron which has been superheated in the electric furnace and the third column indicates the values for oxygentreated cast-iron.
Column Column Column I II III Ultimate tensile stress (kg/sq. mm.) 14-24 22-28 31 Bending strength (kg/sq. mm.) 40-50 4555 Deflection 8-12 12-15 23 blowing said bath with asubstance selected from the group consisting of oxygen and oxygen-enriched gas in the presence of a basic slag to increase the temperature of the bath and to reduce the silicon content to less than 1% reducing the phosphorous content during blowing by introducing into said bath finely divided material containing iron oxide, calcium oxide and sodium carbonate, and adding to said bath silicon-containing materials which cause the formation of a spheroidal graphite structure during solidification of the bath.
2. A process according to claim 1 wherein said finely divided material containing iron oxide, calcium oxide and sodium carbonate is entrained in' said treating gas.
References Cited the file of this patent UNITED STATES PATENTS France Sept. 30, 1953
Claims (1)
1. A PROCESS FOR THE PRODUCTION OF SPHEROIDAL GRAPHITE CAST-IRON COMPRISING PROVIDING A MOLTEN IRON BATH CONTAINING SILICON AND PHOSPHOROUS, SAID BATH BEING PRODUCED BY MELTING A NORMAL CHARGE IN AN ACID CUPOLA FURNACE, BLOWING SAID BATH WITH A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF OXYGEN AND OXYGEN-ENRICHED GAS IN THE PRESENCE OF A BASIC SLAG TO INCREASE THE TEMPERATURE OF THE BATH AND TO REDUCE THE SILICON CONTENT TO LESS THAN 1%, REDUCING THE PHOSPHOROUS CONTENT DURING BLOWING BY INTRODUCING INTO SAID BATH FINELY DIVIDED MATERIAL CONTAINING IRON OXIDE, CALCIUM OXIDE AND SODIUM CARBONATE, AND ADDING TO SAID BATH SILICON-CONTAINING MATERIALS WHICH CAUSE THE FORMATION OF A SPHEROIDAL GRAPHITE STRUCTURE DURING SOLIDIFICATION OF THE BATH.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US696922A US2937084A (en) | 1957-11-18 | 1957-11-18 | Process for production of high-grade cast-iron |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US696922A US2937084A (en) | 1957-11-18 | 1957-11-18 | Process for production of high-grade cast-iron |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US2937084A true US2937084A (en) | 1960-05-17 |
Family
ID=24799066
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US696922A Expired - Lifetime US2937084A (en) | 1957-11-18 | 1957-11-18 | Process for production of high-grade cast-iron |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | US2937084A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3155498A (en) * | 1961-12-27 | 1964-11-03 | Bethlehem Steel Corp | Ductile iron and method of making same |
| US3285739A (en) * | 1964-01-06 | 1966-11-15 | Petrocarb Inc | Process for producing nodular cast iron |
| US3807989A (en) * | 1971-04-07 | 1974-04-30 | Centre Rech Metallurgique | Refining hematite pig iron |
| CN105861815A (en) * | 2016-06-08 | 2016-08-17 | 江苏省冶金设计院有限公司 | Dephosphorization iron-increasing method for high-phosphorus iron ore |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1053342A (en) * | 1951-04-06 | 1954-02-02 | Improvements in the processing of cast iron and cast iron | |
| US2675308A (en) * | 1947-03-22 | 1954-04-13 | Int Nickel Co | Art of using magnesium-containing addition agents to produce spheroidal graphite cast iron |
| GB746994A (en) * | 1953-05-06 | 1956-03-21 | Electro Chimie Metal | Improvements in or relating to the desulphurisation and desiliconising of pig iron |
| US2781256A (en) * | 1953-11-23 | 1957-02-12 | United States Steel Corp | Process for the rapid removal of sulphur and silicon from pig iron |
-
1957
- 1957-11-18 US US696922A patent/US2937084A/en not_active Expired - Lifetime
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2675308A (en) * | 1947-03-22 | 1954-04-13 | Int Nickel Co | Art of using magnesium-containing addition agents to produce spheroidal graphite cast iron |
| FR1053342A (en) * | 1951-04-06 | 1954-02-02 | Improvements in the processing of cast iron and cast iron | |
| GB746994A (en) * | 1953-05-06 | 1956-03-21 | Electro Chimie Metal | Improvements in or relating to the desulphurisation and desiliconising of pig iron |
| US2781256A (en) * | 1953-11-23 | 1957-02-12 | United States Steel Corp | Process for the rapid removal of sulphur and silicon from pig iron |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3155498A (en) * | 1961-12-27 | 1964-11-03 | Bethlehem Steel Corp | Ductile iron and method of making same |
| US3285739A (en) * | 1964-01-06 | 1966-11-15 | Petrocarb Inc | Process for producing nodular cast iron |
| US3807989A (en) * | 1971-04-07 | 1974-04-30 | Centre Rech Metallurgique | Refining hematite pig iron |
| CN105861815A (en) * | 2016-06-08 | 2016-08-17 | 江苏省冶金设计院有限公司 | Dephosphorization iron-increasing method for high-phosphorus iron ore |
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