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CA1052579A - Method of making steel - Google Patents

Method of making steel

Info

Publication number
CA1052579A
CA1052579A CA209,834A CA209834A CA1052579A CA 1052579 A CA1052579 A CA 1052579A CA 209834 A CA209834 A CA 209834A CA 1052579 A CA1052579 A CA 1052579A
Authority
CA
Canada
Prior art keywords
granules
refining
steel
location
method defined
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
Application number
CA209,834A
Other languages
French (fr)
Inventor
Paul Metz
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Arcelor Luxembourg SA
Original Assignee
Individual
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Application granted granted Critical
Publication of CA1052579A publication Critical patent/CA1052579A/en
Expired legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C21METALLURGY OF IRON
    • C21CPROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/56Manufacture of steel by other methods
    • C21C5/567Manufacture of steel by other methods operating in a continuous way

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
  • Manufacture Of Iron (AREA)

Abstract

ABSTRACT OF THE DISCLOSURE

Steel products are formed by first preparing iron granules at a location adjacent a source of iron ore and the like. These granules are then transported to a second location adjacent an outlet for steel products where the granules are preheated and then fused and refined. Hot waste gas from the fusing and refin-ing steps is employed for the preheating operation. The refined liquid steel is then degassed and cast at the second location into steel products.

Description

~05'~79 The present invention relates to a method of making steel.
There are known two main methods for producing steel.
The first known method is based on the continuous oxygen refining of the raw iron as it exits in liquid from a blast furnace. The second method is based on the treatment of iron ore with a product having a carbon base. Thus the first method is based on oxidation and the second on reduction, The principal advantage of these systems lies in the possibility of directly transforming in a continuous succession of steps the primary materials first into liquid steel and then into liquid intermediate products. In addition the plants carry-ing out these processes have certain advantages over the usual steel-making plants, in particular they are smaller in size and function at a lower unit cost. Also in such plants maintenance is reduced considerably, as are the difficulties inherent in the displacement of liquid metals, and the purification of the exhaust gases. It is also possible in such plants to use a high degree of automation so as to further reduce unit cost.
Although the quality of the steel obtained in this manner is entirely satisfactory for most purposes, it is nontheless necessary for certain uses to further refine the steel.
It is therefore necessary to transport to most of the plants which carry out the continuous production and refining of steel at least a part of a basic material such as coal, coke, ore, agglomerates of ore pellets, sponge iron, and the like. In addition, the distribution of the finished product to the various outlets, either in the form of ingots, bitlets or blooms, also presents a considerable difficulty. Thus one of the principal factors in the cost of a gîven steel product is often determined by the difficulty in transporting the various primary materials and/or the finished product, ~OSZ579 It is therefore an object of the present invention to provide an improved method of producing steel.
Another object is the provision of such a method which overcomes the above-given disadvantages.
These objects are attained according to the present invention in a method wherein raw iron produced in a reduction furnace, such as a blast furnace, from raw or prepared ore is transformed into granules at a first location. Thereafter the granules are displaced to a second location wherein they are converted into liquid steel by means of continuous preheating followed by smelting of these granules by means of a burner and/or an electric arc, then refining of the melted metal by means of oxygen and the addition of slag, and continuous sepa-ration of the slag from the refined steel.
The invention relates to a method of making steel comprising the steps of:
feeding iron ore into a reduction furnace and forming iron granules at a first location adjacent a source of iron ore;
transporting said granules to a second location remote from said first location and proximal to a consumer of products;
continuously preheating said granules at said second location to a temperature between about 800C and their softening point;
continuously melting the preheated granules at said second location:
continuously refining the melted granules to liquid steel at said second location with the addition of slag formers and oxygen; and continuously separating the refined liquid steel from the slag and forming same into a steel product.
-2-~J~

~OSZ579 According to another feature of this inventlon this re-fined steel is continuously collected in a finishing vessel or ladle serving to equalize the mixture and give it e~actly the right temperature. In addition it is possible to degas this melt in the ladle by means of vacuum. Thereafter the melt is poured into molds for the formation of ingots or the like.
According to the invention the operations of smelting and refining can be carried out in separate smelting and refining locations in the steel-making plant. They can also be carried out in a single chamber which therefore serves these two functions.
Gases produced during the smelting of the granules and the refining of the liquified metal are recuperated and employed at least partly for preheating the granules to be melted.
The process according to the present invention, is semi-continuous. The intermediate conversion of the raw iron into solid granules can thus be carried out adjacent a very large stock of ore, usually right at the locus of the deposit of such minerals, at the edge of an ocean, or the like. These granules of crude ore -2a-.~'.
, 105'~579 are then transported to the location where they are formed into steel intermediate products as well as, if desired, into finished products, This last step is carried out close to the location where these products are to be used. Keeping such raw iron gran-ules is much easier than keeping intermediate products or finished products. It is also much easier to transport raw iron granules both on water and on land. The fact that these granules are very low in impurities makes their transport much more economically feasible than the transport of highly impure ore or the like.
It is another advantage of the invention that the part-icles of raw iron are a high-quality starting material. Their residual oxygen content is low so that their reduction is relative-ly easy. In addition such particles contain a very large propor-tion of carbon which has an important metallurgical role during their smelting in that it contributes to the reduction of the oxides and to the homogenization of the melt by adding heat thereto.
Practically speaking the process according to the present invention can be carried out in several manners. The techniques developed in the continuous refining of steel are employed for the refining step at least of the present invention.
Thus during the phase in which the primary materials are prepared, the liquid iron prepared in a shaft furnace is made into fine porous particles, for example, by granulization by use of water ti.e. pouring the molten metal into a water bath).
These granules are transported to the location where they are to be made into steel and stockpiled. Before smelting they are gradually reheated to a temperature of between 800-900C
and their softening point. The gases produced by the blast furnace areused in accordance with the present invention to preheat these particles in addition to a supplemental heat source. The pre-heating can be carried out, for example, in a rotary kiln or lOS'~579 hearth, on a displaceable grate, in a fluidized bed, or simply in the feed conduit for the fusion chamber. The large surface area of the particles, due to their small granularity (greater than lOmm) and to their considerable porosity, allows an efficient con-tact between the gas and the liquid so as to accelerate the pre-heating and the smelting of the particles.
In accordance with yet another feature of the present invention the preheated particles are continuously fed into the smelting chamber of the plant. Depending on the composition of the iron and the quantity of particles or granules to be melted, this chamber is heated inductively, or by combustion, as by means of oxy-fuel or plasma burners or by an electric arc. The feed rate for the granules depends on the fusion rate and the refining speed of the plant.
The operations of smelting and refining can be carried out in the same heated chamber into which the preheated granules, oxygen, slag-forming additives, and even carbon are added. The liquid steel suspended in the slag is poured off into a decanting vessel at such a rate that the level of metal in the smelting and refining chamber remains virtually constant.
The smelting location can also be in communication with a separate refining chamber. The metal then circulates contin-uously from one chamber to the other by overflow, by siphon, or by gravity as the continuously fed solid granules are fused in the first chamber. In the refining chamber the liquid melt is subjected to oxygen blown in by one or more lances. Limestone and fluxes can be introduced separately or with the oxygen. It can be useful to provide a second refining space following the second refiner for the supplementary refining of a melt having a high phosphorous content, In the refining chamber the light slag can be displaced countercurrent to the metal, such that the refined steel and the ~OSZ579 slag remain separate. The refining chamber can also be subdivided into two separate compartments. In the first compartment oxygen, mixed with slag-forming additives if necessary, is injected into the liquid-metal meltwhich is continuouslyreplenished from the up-stream smelting chamber. The slag-metal emulsion which forms above the layer of metal in this compartment runs over into the second neighboring compartment in which the steel separates from the slag by decantation so as to allow separate extraction of the two phases.
In the two above-described cases the refined metal pours continuously into the finishing vessel of the ladle or the mixing type in which the final steps of the steel production and eventual-ly the degassing of the steel is carried out, The steel so made can be directly poured into ingot molds or into other continuous forming devices.
The refining can also be carried out by pulverization of the melted iron, To this end a stream of liquid iron coming from the fusion chamber and falling freely in a reaction chamber is broken up by at least one continuous jet of oxidizing gas and the addition of pulverants so that the drops so formed react with the impurities to be extracted from the metal. The refined metal is captured at the bottom of the reaction chamber where the slag floating on top is skimmed off and the metal is withdrawn contin-uously from below so that its composition and temperature can be corrected before use.
The process according to the present invention therefore allows the production by a continuous method of many different kinds of steel. Such steels can be of very different compositions, pure or alloyed. In any case the desired compositions can be produced accurately and predictably.
In accordance with yet another feature of this invention the continuous operations are all carried out by means of a central lOSZ579 computer which automates the entire plant.
The above and other objects, features, and advantages will become more readily apparent from the following, reference being made to the accompanying drawing in which the sole figure is a schematic view illustrating the steel-producing system according to the present invention, As shown in the drawing iron ore, limestone, and coke are fed to a blast furnace 10 at a first location 1 so as to pro-duce iron which is fed in liquid form to a granulizer 11 where it is poured into a body of water for the formation of iron granules.
Thereupon these granules are transported to a second location 2 and fed to a preheater 12 where they are heated to a temperature of approximately 950C and fed to the fuser compartment 13' of a two-compartment smelter-refiner 13" where oxygen, carbon, and slag formers are added s/o as to purify the melt, The smelter i7ld~cti~æ S' 13' can be heated i~d~lvely, by means of a burner, or by means of an electric arc and the hot waste gases produced by both the smelter 13' and refiner 13" are fed back to the preheater where they serve to preheat the granules coming from the location 1.

From the refiner 13" the melt pours over into a decantation ~ bho~ horL~
chamber 13'''. If the melt is high in ~osphs~rous content, after refining in the compartment 13" it is fed to another refiner 14 where it is further refined and more slag is drawn off, Thereupon the refined melt is fed to a vacuum treatment chamber 15 where it is degassed. Thereafter the steel is cast at 16 into ingots or other intermediate or finished products.
The location 1 according to the present invention is directly at the mine or at a convenient location for the delivery of the necessary basic materials to it. On the other hand the location 2 is near an outlet where the finished product is needed.
The transport between location 1 and 2 can either be carried out - over the water or over land, as the iron granules are relatively ~05Z579 easy freight to handle. A refining and slag handlingsy~tem as may be used here is shown in the aforementioned application.
The entire operation at both locations 1 and 2 is con-trolled by respective computers 17 and 18 which monitor the various temperatures and control the operations for continuous production in each of the separate locations 1 and 2.

Claims (10)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. A method of making steel comprising the steps of:
feeding iron ore into a reduction furnace and forming iron granules at a first location adjacent a source of iron ore:
transporting said granules to a second location remote from said first location and proximal to a consumer of products;
continuously preheating said granules at said second location to a temperature between about 800°C and their softening point;
continuously melting the preheated granules at said second location;
continuously refining the melted granules to liquid steel at said second location with the addition of slag formers and oxygen; and continuously separating the refined liquid steel from the slag and forming same into a steel product.
2. The method defined in claim 1, further comprising the step of continuously collecting said liquid steel in a vessel and homogenizing and degassing said liquid steel in said vessel prior to forming same into said product.
3. The method defined in claim 2 wherein said granules are preheated by a waste gas produced at a subsequent step in the method.
4. The method defined in claim 3 wherein the steps of melting and refining are carried out in the same place.
5. The method defined in claim 3 wherein the steps of melting and refining are carried out in separate compartments.
6. The method defined in claim 3 wherein the refining step produces a light slag.
7. The method defined in claim 6 wherein said slag is circulated countercurrent to said liquid steel.
8. The method defined in claim 5 further comprising the step of passing said liquid steel into a decanting compart-ment adjacent the refining compartment after refining of said melted granules.
9. The method defined in claim 5 wherein said melted granules are refined by pulverization thereof.
10. The method defined in claim 5, further comprising the step of further refining said liquid steel subsequent to the refining of said melted granules and prior to the separa-tion of said steel from the slag.
CA209,834A 1973-09-21 1974-09-20 Method of making steel Expired CA1052579A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
LU68467A LU68467A1 (en) 1973-09-21 1973-09-21

Publications (1)

Publication Number Publication Date
CA1052579A true CA1052579A (en) 1979-04-17

Family

ID=19727473

Family Applications (1)

Application Number Title Priority Date Filing Date
CA209,834A Expired CA1052579A (en) 1973-09-21 1974-09-20 Method of making steel

Country Status (19)

Country Link
JP (1) JPS589124B2 (en)
AR (1) AR201788A1 (en)
AT (1) AT347489B (en)
AU (1) AU7354674A (en)
BE (1) BE819876A (en)
BR (1) BR7407841D0 (en)
CA (1) CA1052579A (en)
CH (1) CH592740A5 (en)
DD (1) DD114618A5 (en)
DE (1) DE2444115A1 (en)
FR (1) FR2244823B1 (en)
GB (1) GB1487565A (en)
IT (1) IT1019346B (en)
LU (1) LU68467A1 (en)
NL (1) NL7412458A (en)
NO (1) NO743386L (en)
PL (1) PL91749B1 (en)
SE (1) SE7411798L (en)
ZA (1) ZA745957B (en)

Also Published As

Publication number Publication date
ATA748474A (en) 1978-05-15
LU68467A1 (en) 1975-06-16
BE819876A (en) 1975-03-13
NO743386L (en) 1975-04-14
BR7407841D0 (en) 1975-07-29
AU7354674A (en) 1976-03-25
FR2244823B1 (en) 1980-02-08
FR2244823A1 (en) 1975-04-18
SE7411798L (en) 1975-03-24
DD114618A5 (en) 1975-08-12
ZA745957B (en) 1975-09-24
DE2444115A1 (en) 1975-03-27
JPS589124B2 (en) 1983-02-19
GB1487565A (en) 1977-10-05
AR201788A1 (en) 1975-04-15
PL91749B1 (en) 1977-03-31
JPS5077207A (en) 1975-06-24
IT1019346B (en) 1977-11-10
AT347489B (en) 1978-12-27
NL7412458A (en) 1975-03-25
CH592740A5 (en) 1977-11-15

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