GB2052563A - Process for the Treatment of Molten Iron with Increased Scrap Content - Google Patents
Process for the Treatment of Molten Iron with Increased Scrap Content Download PDFInfo
- Publication number
- GB2052563A GB2052563A GB7922037A GB7922037A GB2052563A GB 2052563 A GB2052563 A GB 2052563A GB 7922037 A GB7922037 A GB 7922037A GB 7922037 A GB7922037 A GB 7922037A GB 2052563 A GB2052563 A GB 2052563A
- Authority
- GB
- United Kingdom
- Prior art keywords
- calcium carbide
- process according
- oxygen
- molten iron
- constituents
- 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.)
- Granted
Links
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 title claims abstract description 68
- 238000000034 method Methods 0.000 title claims abstract description 49
- 229910052742 iron Inorganic materials 0.000 title claims abstract description 34
- 239000005997 Calcium carbide Substances 0.000 claims abstract description 55
- 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 claims abstract description 55
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 39
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 39
- 239000001301 oxygen Substances 0.000 claims abstract description 39
- 239000007789 gas Substances 0.000 claims abstract description 15
- 239000000470 constituent Substances 0.000 claims abstract description 12
- 238000005275 alloying Methods 0.000 claims abstract description 7
- 230000005496 eutectics Effects 0.000 claims abstract description 3
- 229910000831 Steel Inorganic materials 0.000 claims description 19
- 239000010959 steel Substances 0.000 claims description 19
- 150000001875 compounds Chemical class 0.000 claims description 8
- 230000000694 effects Effects 0.000 claims description 7
- 238000002347 injection Methods 0.000 claims description 6
- 239000007924 injection Substances 0.000 claims description 6
- 238000002485 combustion reaction Methods 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 3
- 238000007670 refining Methods 0.000 claims description 2
- 230000008018 melting Effects 0.000 claims 1
- 238000002844 melting Methods 0.000 claims 1
- 239000000155 melt Substances 0.000 description 15
- 238000006243 chemical reaction Methods 0.000 description 11
- 229910000805 Pig iron Inorganic materials 0.000 description 10
- 239000002893 slag Substances 0.000 description 9
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 7
- 235000011941 Tilia x europaea Nutrition 0.000 description 7
- 239000004571 lime Substances 0.000 description 7
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 6
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 6
- 239000005864 Sulphur Substances 0.000 description 6
- 229910052698 phosphorus Inorganic materials 0.000 description 6
- 239000011574 phosphorus Substances 0.000 description 6
- 238000007664 blowing Methods 0.000 description 5
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 4
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 4
- 239000000292 calcium oxide Substances 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 3
- 229910010271 silicon carbide Inorganic materials 0.000 description 3
- 239000004411 aluminium Substances 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- WUKWITHWXAAZEY-UHFFFAOYSA-L calcium difluoride Chemical compound [F-].[F-].[Ca+2] WUKWITHWXAAZEY-UHFFFAOYSA-L 0.000 description 2
- 229910001634 calcium fluoride Inorganic materials 0.000 description 2
- GNTDGMZSJNCJKK-UHFFFAOYSA-N divanadium pentaoxide Chemical compound O=[V](=O)O[V](=O)=O GNTDGMZSJNCJKK-UHFFFAOYSA-N 0.000 description 2
- 238000005187 foaming Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 150000002484 inorganic compounds Chemical class 0.000 description 2
- 229910010272 inorganic material Inorganic materials 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000010079 rubber tapping Methods 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 229910014813 CaC2 Inorganic materials 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- 229910001336 Semi-killed steel Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000009529 body temperature measurement Methods 0.000 description 1
- 150000001642 boronic acid derivatives Chemical class 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 229940117975 chromium trioxide Drugs 0.000 description 1
- WGLPBDUCMAPZCE-UHFFFAOYSA-N chromium trioxide Inorganic materials O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 description 1
- GAMDZJFZMJECOS-UHFFFAOYSA-N chromium(6+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Cr+6] GAMDZJFZMJECOS-UHFFFAOYSA-N 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 229910000514 dolomite Inorganic materials 0.000 description 1
- 239000010459 dolomite Substances 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 230000002045 lasting effect Effects 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 239000011777 magnesium Substances 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 238000010309 melting process Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 229910000480 nickel oxide Inorganic materials 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000008247 solid mixture Substances 0.000 description 1
- 238000009628 steelmaking Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 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
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
- C21C5/32—Blowing from above
-
- 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
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
- C21C5/34—Blowing through the bath
-
- 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
Abstract
A process for the treatment of molten iron having an increased scrap content in a converter comprises injecting into or onto the molten iron an oxygen-containing gas, preferably oxygen itself, which contains calcium carbide. The calcium carbide may be of commercial grade or in the form of eutectic calcium carbide, is suitably injected in an amount of 5 to 125, preferably 30 to 60, kg per tonne molten iron, and may be injected with other oxidisable, alloying or slag- forming constituents.
Description
SPECIFICATION
Process for the Treatment of Molten Iron with Increased Scrap Content
This invention relates to a process for the treatment of molten iron by simultaneously increasing the scrap rate in the converter.
It is well known that from 25 to 30 weight % of scrap can be added to the pig iron in a steel converter. The heat of combustion of the carbon, manganese, silicon and other elements in the pig iron is sufficient to melt a certain amount of scrap and to raise the temperature of the melt to the required degree for molten steel.
In some cases, however, there is a desire to increase further the proportion of scrap, in order to make the steel production capacity flexible, to adapt it to market and production requirements and, especially, to permit processing of excess scrap which is more reasonably priced than pig iron. It is also desirable to make basic oxygen furnace (BOF) converters less dependent upon the pig iron supply, for example to mitigate the effect of breakdowns in blast furnace operation upon steel-making.
Further, the conventional oxygen top-blowing technique permits the temperature in the converter to be increased within very narrow limits only, and involves a high specific cost, since the after-blow causes increased iron losses. Consequently means have long been sought to improve the heat balance in the converter by adding an agent having a high exothermic reaction to such an extent that addition of greater proportions of scrap becomes possible.
Processes have been proposed for increasing the scrap rate by, for example, mixing oxygen with fuel gas in special burners and in this way increasing the heat balance of the converter. It has also been proposed to preheat and/or melt down the scrap with a flame lance, introducing oxidisable material for example iron, magnesium, calcium and aluminium into the flame to increase the heat supply.
It has further been proposed to replace a part of the fuel with calcium carbide suspended in a combustible organic compound in order to produce an exothermic reaction on the surface of the molten metal.
The common feature of all these processes known hitherto is that another gas, charged if required with an oxidisable solid must be added or supplied, by means of a special jet, to the oxygen jet after the latter leaves the lance, in order to develop combustion energy upon impact with the molten iron.
In order to simplify such a process, it has been proposed to add calcium carbide to the melt in lump form during the blowing process. The thermal energy developed by combustion of 1 kg carbide should, in theory, be sufficient to raise approximately 6 kg iron from room temperature to a temperature of 16300 C. This high degree of efficiency, required to render the addition of carbide economical, is not, however, attained in practice. Moreover, the resulting increased foaming of the slag causes considerable disruption to the course of the operation, and far outweighs any possible advantages.
The present invention seeks to provide a process for treating molten iron in a simplified manner which permits the proportion of scrap in the converter, preferably a BOF converter, to be increased, and which eliminates the current disadvantages of such processes.
The present invention provides a process for the treatment of molten iron having an increased scrap content in a converter, which comprises injecting into or onto the molten iron an oxygencontaining gas which contains calcium carbide.
This procedure ensures substantially complete and uniform reaction. The product of the oxidized calcium carbide is a very highly reactive calcium oxide which accelerates metallurgical reactions (for example, desulphurization and dephosphorization) which are required anyway. This, in turn, permits the lime charge to be substantially reduced, thus shortening the lime dissolution princess.
A special advantage of the process according to the present invention is derived from using oxygen of industrial purity to which calcium carbide can be added in any required amount without any problem.
Surprisingly, it has been found that even finely particulate calcium carbide can be handled together with oxygen up to a temperature of approximately 2000C without any risk of the carbide being destroyed by oxidation and its efficiency thereby impaired.
Improvements in recent years in the pneumatic transport and introduction of reactive constituents ground as fine as dust into molten iron enable the present process to be carried out with controlled injection, by means of oxygen, of finely particulate to granular calcium carbide, alone or together with other constituents, into the molten iron at specific intervals or in specific amounts per unit time, either from above using a lance or by means of known jets through the bottom of the converter.
Since oxygen lances for top-blown converters are water cooled, the temperature of the oxygen up to the orifice is as a rule approximately 1 OOC. The shape of the nozzle causes the oxygen to expand when it leaves the lance, cooling it even further. Consequently, heating of the gas-solid mixture to a temperature at which a reaction between oxygen and calcium carbide could start, is impossible at this stage, and combustion occurs only between the orifice of the lance and the surface of the metal, ignition being caused by the heat of, for example the pig iron or the steel bath at the point of impact.
To obtain a complete reaction, oxygen is preferably used in excess.
The calcium carbide is preferably injected in the form of industrial calcium carbide, containing approximately 75 to 83% CaC2, in a finely ground or crushed form.
The grain size of the calcium carbide to be injected and of any other metals, metal oxides or other materials which may be added can vary widely and may be up to 20 mm. However, a grain size of up to approximately 1 mm is preferred.
As an alternative to commercial carbide, so-called eutectic carbide, that is carbide containing a higher proportion of calcium oxide, can be used with advantageous effect, in that an increased proportion of metallurgically effective lime (CaO) can then be offered together with a reduced heating action.
The amount of calcium carbide to be injected depends on the proportion of scrap charged, on the temperature of the melt and on the composition of the injected carbide. Generally, from 5 to 125 kg and preferably from 30 to 60 kg calcium carbide are injected for every 1 t molten iron to be treated.
These amounts permit adequate temperature control of the molten iron even when a high proportion of scrap is included. The amount of calcium carbide metered into the oxygen also permits the oxygen concentration in the molten iron to be controlled, and enables the oxygen concentration to be adjusted within narrower limits than with conventional processes. Controlled calcium carbide injection also enables the oxidation of alloying metals to be inhibited, the recovery of effective alloying elements, for example aluminium and silicon, to be accurately controlled on tapping, and the oxygen concentration to be adjusted in such a way that certain grades of steel, for example rimming steel and semi-killed steel, can be cast without flaws.
Other oxidisable inorganic compounds, especially silicon carbide may preferably be added to the calcium carbide to enable injection and alloying to be achieved simultaneously.
In addition to the compounds which supply only thermal energy, other compounds, especially metal oxides, which exercise an alloying effect in the steel bath, can be added to the calcium carbide in accordance with the process of the present invention. For this purpose, nickel oxide (Ni-sinter), vanadium pentoxide, chromium trioxide and other oxides and ores are preferably used, depending on the desired grade of steel.
The metal oxides used for alloying can be introduced into the steel bath together with the oxidisable inorganic compounds and the calcium carbide. Alternatively, they can be metered into the oxygen stream in admixture with calcium carbide, or on their own.
The proportion of such compounds or ores can be as much as 50 weight % of the calcium oxide added, and is essentially governed by the grade of steel required and by economic considerations.
Metallurgically-active slag-forming compounds can also be added to the calcium carbide. These include especially calcium fluoride, borates, alumina, lime and mixtures of any two or more thereof.
The forming of a suitable slag is of importance insofar as the iron concentration, that is the proportion of essentially Fe-ll-oxide, in the slag should be as low as possible. On the other hand the nature of the slag must be such that an essentially free zone can form in the region of the injection stream through which the reaction gases can escape. This prevents gases being retained in the slag which would cause it to start foaming, as is the case for example when calcium carbide or silicon carbide is added in lump form.
Depending on the stage of the melting process or the refining reaction or on the concentration of impurities, for example sulphur, in the molten pig iron, the treating gas may be charged with more or
less calcium carbide, and slag-forming compounds, if required (charging in stages). This calcium carbide addition can be increased or decreased continuously; it can, however, also be maintained at the same level throughout the entire treatment time.
The temperature of the molten pig iron is, of course, affected by the amount of scrap added to the charge. However, an increase in the amount of calcium carbide and any other compounds, for example silicon carbide, can quickly control the process. If the temperature of the melt has dropped excessively,
then it can quickly and reliably be raised by doses of calcium carbide or mixtures of calcium carbide and other heat producing compounds, added intermittently.
The process according to the present invention for the treatment of molten iron has been described above with reference to top-blown converters, but the process is equally applicable to the treatment of molten iron in bottom-blown converters. In this latter case, the injected calcium carbide or the reaction products forming in the treatment gas flow through the entire bath from the bottom to the top, ensuring a high degree of reaction. The amounts of undesirable impurities in the steel are rapidly brought down to values close to the reaction equilibrium, and heat transmission from the reaction zone to the melt occurs with practically 100% efficiency.
Although no definitive statement can be made regarding the service life of the refractory lining of the converter after use in the process of the invention, correlations suggest that a 25% improvement in its total service life may be anticipated. This feature represents a further advantage of the present invention.
The following Examples illustrate the invention.
Example 1
The results obtained from a process according to the invention were compared with those obtained from a conventional process. In each case, the figures are the mean of 11 melts.
(a) Comparison, Conventional Method
pig iron 78.5 t
scrap 15t lime 4.5 t
liquid yield 85.5 t
final sulphur concentration 0.021 %
final phosphorus concentration 0.014%
iron yield 91.5%
(b) Method According to the Invention:
pig iron 78.5 t
scrap 31 t
lime 2.1 t
carbide 2.8t
liquid yield approx. 102.5 t
final sulphur concentration 0.014%
final phosphorus concentration 0.007%
iron yield 95.5%
Example 2
The effect of charging the oxygen stream with calcium carbide on the Fe-ll-oxide concentration in the slag and on the concentration of dissolved oxygen in the steel, was examined in a series of 4 melts.
To a charge of, in each case, approximately 100 t liquid steel with concentrations of carbon 0.07%, sulphur 0.02% and phosphorus 0.015,
(a) 41 t scrap were added and 4 t calcium carbide were blown with oxygen onto the melt;
(b) 21 t scrap were added and blown with oxygen without calcium carbide addition.
Results
The Fe-ll-oxide concentration in the slag of the melts treated with calcium carbide was 11-14%, and of the melts treated only with oxygen was 1823%.
The differences between the respective oxygen concentration before tapping were of a similar order. In the liquid steels treated with calcium carbide, the oxygen concentration was 400-600 ppm, in the other melts it was 800-1200 ppm.
Example 3
The effect of the process according to the invention was examined in a series of ten melts in 110 t converter operating by the BOF process.
On average, there were used 85 t pig iron with a phosphorus content of 1.6%, to which 28 t scrap were added.
After a conventional blowing treatment (oxygen charged with 4% calcium oxide) lasting approximately 1 5 minutes, the converter was tilted, partially slagged off and another approximately 29 t scrap were added. The amount of lime to be further added was reduced to 1%, the remainder being replaced by commercial calcium carbide. On average a total of 5 t calcium carbide was blown at a rate of 400 kg/min.
After a further 13-1 6 minutes treatment, a carbon concentration of 0.320.36% was achieved; the sulphur concentration was then 0.011% and the phosphorus concentration 0.008%.
Compared with conventional processes, the charging time was increased by only 3-5 minutes.
The output, however, rose from 146 t/h to 1 70 t/h, giving an output increase of 1 6.4% with improved final phosphorus and sulphur concentrations compared with conventional processes.
Example 4
The heating effect obtained in the process in accordance with the invention was examined for 4
melts each of tap weight 110 t according to the LDAC-process. After working conventionally, there
resulted a temperature which was on average too low by 250C (1 5800C) for the desired grade of steel,
and the melt contained approximately 0.35% carbon.
To correct the temperature, the oxygen stream was charged with commercial calcium carbide
immediately after the last temperature measurement. The blowing rate was 40--50 kg calcium
carbide/minute; after 5 minutes, 2.5-3 kg calcium carbide/t steel had been blown. In this time, the
average temperature increase was 28.50C. The Fe-ll-oxide concentration of the slag was reduced by
an average of 4.5% and the iron yield was consequently correspondingly increased.
Example 5
In a series of six melts with a tap weight of 110 t, produced by the BOF process, the lime charge of approximately 4.5% was reduced to about 1% of the steel weight. The oxygen stream was charged with a mixture of fine-grained calcium carbide, dolomite and calcium fluoride in a ratio of 100:1 5:1 0; the blowing rate was 250 kg mixture/minute. The scrap amount was raised by 1 5 t to 44 t. The degree of desulphurisation was increased in this manner from an average of 23% to 59%. The Fe-ll-oxide concentration in the slag dropped by about 12%.
Claims (18)
1. A process for the treatment of molten iron having an increased scrap content in a converter,
which comprises injecting into or onto the molten iron an oxygen-containing gas which contains
calcium carbide.
2. A process according to claim 1, wherein the oxygen-containing gas and calcium carbide are
injected through a lance onto the surface ot the molten iron.
3. A process according to claim 1, wherein the oxygen-containing gas and calcium carbide are
injected into the molten iron through a jet in the bottom of the converter.
4. A process according to any one of claims 1 to 3, wherein the oxygen-containing gas is oxygen
or a compound containing oxygen.
5. A process according to any one of claims 1 to 4, wherein the calcium carbide is commercial
calcium carbide.
6. A process according to any one of claims 1 to 4, wherein the calcium carbide is eutectic
calcium carbide.
7. A process according to any one of claims 1 to 6, wherein from 5 to 1 25 kg calcium carbide are
injected per tonne of molten iron.
8. A process according to claim 7, wherein from 30 to 60 kg calcium carbide are injected per
tonne of molten iron.
9. A process according to any one of claims 1 to 8, wherein the oxygen-containing gas also
contains one or more other oxidisable constituents.
10. A process according to any one of claims 1 to 9, wherein the oxygen-containing gas also
contains one or more constituents which have an alloying effect in steel.
11. A process according to any one of claims 1 to 10, wherein the oxygen-containing gas also
contains one or more metallurgically-effective slag-forming constituents or materials which are
converted to slag-forming constituents by combustion or melting.
12. A process according to any one of claims 9 to 11, wherein the oxygen-containing gas
contains up to 50 weight % of such additional constituents, relative to the calcium carbide.
1 3. A process according to any one of claims 1 to 12, wherein the calcium carbide and any other
constituents have a grain size of up to 20 mm.
14. A process according to claim 13, wherein the calcium carbide and any other constituents
have a grain size of up to 1 mm.
1 5. A process according to any one of claims 1 to 14, wherein injection of the calcium carbide
and any other constituents into or onto the molten iron is carried out stepwise as a function of the
progress of refining.
1 6. A process according to any one of claims 1 to 1 5, wherein injection of the calcium carbide and any other constituents into or onto the molten iron is carried out intermittently as a function of the
temperature of the molten iron.
17. A process according to claim 1 carried out substantially as described in any one of the
Examples herein.
18. Iron or steel which has been obtained by a process according to any one of claims 1 to 1 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7922037A GB2052563B (en) | 1979-06-25 | 1979-06-25 | Process for the treatment of molten iron with increased scrap content |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7922037A GB2052563B (en) | 1979-06-25 | 1979-06-25 | Process for the treatment of molten iron with increased scrap content |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2052563A true GB2052563A (en) | 1981-01-28 |
| GB2052563B GB2052563B (en) | 1983-10-12 |
Family
ID=10506068
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7922037A Expired GB2052563B (en) | 1979-06-25 | 1979-06-25 | Process for the treatment of molten iron with increased scrap content |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2052563B (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0115271A1 (en) * | 1983-01-06 | 1984-08-08 | Union Carbide Corporation | Steelmaking process using calcium carbide as fuel |
| GB2213834A (en) * | 1987-12-21 | 1989-08-23 | N Proizv Ob Tulatschermet | Steelmaking process in oxygen-blown converter |
-
1979
- 1979-06-25 GB GB7922037A patent/GB2052563B/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0115271A1 (en) * | 1983-01-06 | 1984-08-08 | Union Carbide Corporation | Steelmaking process using calcium carbide as fuel |
| GB2213834A (en) * | 1987-12-21 | 1989-08-23 | N Proizv Ob Tulatschermet | Steelmaking process in oxygen-blown converter |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2052563B (en) | 1983-10-12 |
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| PCNP | Patent ceased through non-payment of renewal fee |