WO2007102881A2 - Composition destinée à réduire le laitier d'affinage - Google Patents

Composition destinée à réduire le laitier d'affinage Download PDF

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Publication number
WO2007102881A2
WO2007102881A2 PCT/US2006/060003 US2006060003W WO2007102881A2 WO 2007102881 A2 WO2007102881 A2 WO 2007102881A2 US 2006060003 W US2006060003 W US 2006060003W WO 2007102881 A2 WO2007102881 A2 WO 2007102881A2
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WIPO (PCT)
Prior art keywords
weight percent
slag
silicon
reducing agent
calcium
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PCT/US2006/060003
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English (en)
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WO2007102881A3 (fr
Inventor
Jeremy A.T Jones
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Nupro Corporation
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Publication date
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Publication of WO2007102881A2 publication Critical patent/WO2007102881A2/fr
Publication of WO2007102881A3 publication Critical patent/WO2007102881A3/fr

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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
    • C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
    • 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
    • C21C7/076—Use of slags or fluxes as treating agents
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B5/00—General methods of reducing to metals
    • C22B5/02—Dry methods smelting of sulfides or formation of mattes
    • C22B5/06—Dry methods smelting of sulfides or formation of mattes by carbides or the like
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B7/00—Working up raw materials other than ores, e.g. scrap, to produce non-ferrous metals and compounds thereof; Methods of a general interest or applied to the winning of more than two metals
    • C22B7/04—Working-up slag
    • 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

Definitions

  • This invention relates in one embodiment to an additive for making a ladle slag composition used in steel making, and more particularly to an additive that that enables the production of a desired slag within a specified time.
  • An additive used in steel making for making a ladle slag composition which comprises calcium carbide, a second reducing agent (chosen from silicon metal, ferro- silicon, calcium silicon, silicon carbide, titanium metal, ferro-titanium, titanium carbide) and optionally at least one fluxing agent selected from the group consisting of calcium aluminate, glass, oxides of elements of Groups IA, MA, IMA, IVA of the Periodic Table of the Elements, fluorides of elements of Groups 1 A, MA, and IMA of the Periodic Table, silicon carbide, and mixtures thereof, and from about 0 to about 20 weight percent of a metal carbonate.
  • a second reducing agent chosen from silicon metal, ferro- silicon, calcium silicon, silicon carbide, titanium metal, ferro-titanium, titanium carbide
  • at least one fluxing agent selected from the group consisting of calcium aluminate, glass, oxides of elements of Groups IA, MA, IMA, IVA of the Periodic Table of the El
  • compositions for synthesizing and/or optimizing and/or treating ladle slags in steel making have disclosed compositions for synthesizing and/or optimizing and/or treating ladle slags in steel making.
  • United States patent 5,279,639, of Kemeny et al. discloses a composition for synthesizing and treating ladle slags comprised of from about 5 to about 50 weight percent of calcium carbide, from about 10 to about 20 weight percent of magnesium carbonate, from about 40 to about 55 weight percent of calcium carbonate, from about 5 to about 20 weight percent of alumina, and from about 2 to about 5 weight percent of coke.
  • the entire disclosure of this United States patent is hereby incorporated by reference into this specification.
  • Kemeny, et al The composition of Kemeny, et al is effective and has achieved a substantial amount of commercial success. However, since the commercial introduction of this composition, pressures have increased upon the domestic steel making industry to substantially increase productivity, especially with the increased sales of foreign steel dumped into the United States.
  • One problem with the Kemeny et al composition is that is takes a relatively long period of time for it to treat the slag in order to produce the desired slag composition.
  • United States patent 6,267,798, of Kemeny et al. discloses a composition for treating steelmaking slags wherein a slag composition is formulated containing steelmaking slag and from about 0.5 to about 10 weight percent of reducing agent.
  • the steelmaking slag contains from about 25 to about 55 weight percent of calcium oxide, from about 10 to about 50 weight percent of ferrous oxide, from about 5 to about 20 weight percent of magnesium oxide, from about 5 to about 20 weight percent of silicon oxide, and from about 0.5 to about 8 weight percent of manganese oxide.
  • the reducing agent contains both calcium carbide and elemental aluminum.
  • From about 5 to about 80 weight percent of the reducing agent is comprised of calcium carbide, and from about 10 to about 50 weight percent of such reducing agent is comprised of elemental aluminum.
  • the entire disclosure of this United States patent is hereby incorporated by reference into this specification.
  • the composition of the US 6,267,798 patent is also effective and has achieved a substantial amount of commercial success.
  • This patent provides a method to more readily facilitate the production of the desired ladle slag than prior art compositions but only for those grades of steel for which the process route allows for the use of aluminum as a reducing agent.
  • many grades of steel are restricted from the use of aluminum as a reducing agent because this may cause processing problems with the steel in subsequent downstream operations such as casting.
  • the desired refining slag composition disposed on top of the steel in the ladle will vary according to steel grade and other parameters. In general, however, this desired refining slag composition is comprised of from about 40 to about 65 weight percent of calcium oxide, from about 10 to about 40 weight percent of silicon oxide, from about 5 to about 20 weight percent of magnesium oxide, from about 0 to about 10 weight percent of aluminum oxide, from about 0 to about 15 weight percent of calcium fluoride, and from about 0.5 to about 12 weight percent of a mixture containing ferrous oxide and manganese oxide.
  • the desired refining slag preferably serves to provide a continuous partially molten oxide phase on the surface of the steel being treated, to capture and retain inclusive non-metallic material present in the steel (such as silicon oxide or titanium oxide), to be either non-oxidizing or reducing with respect to the steel, to control the sulfur content of the steel, to provide a non-corrosive environment for the refractory ladle linings, to promote stable arcing during electric arc reheating in the ladle, to protect the steel from contact with the atmosphere, and to provide thermal insulation.
  • inclusive non-metallic material present in the steel such as silicon oxide or titanium oxide
  • embodiments of the present invention are provided that meet at least one or more of the following objects of the present invention. It is an object of this invention to provide an additive for treating ladle slag specifically for steels restricted from the use of aluminum as a reducing agent, which more readily facilitates the production of the desired ladle slag than prior art compositions.
  • an additive for making a ladle slag composition which comprises calcium carbide, a second reducing agent, and optionally at least one fluxing agent selected from the group consisting of calcium aluminate, glass, oxides of elements of Groups IA, MA, IMA, IVA of the Periodic table, fluorides of elements of Groups 1A, MA, and IMA of the Periodic table, silicon carbide, and mixtures thereof.
  • an additive used in steel making for making a ladle slag composition comprising about 5 to about 60 weight percent of a first reducing agent, and about 10 to about 70 weight percent of a second reducing agent, wherein the first reducing agent consists essentially of calcium carbide; and the second reducing agent is selected from the group consisting of silicon, titanium, silicon carbide, and mixtures thereof.
  • the additive may further comprise a fluxing material selected from the group consisting of lime, calcium aluminate, calcium silicate, glass, calcium fluoride, by-product oxides, steelmaking slag, recycled slag, or combinations thereof.
  • the reducing agents of the additive are preferably provided in the form of particles, and at least about 90 weight percent of the particles are within a size range of from about 0.1 to about 0.7 inches.
  • a slag composition comprised of steelmaking slag and from about 0.5 to about 15 percent of reducing agent by total weight of steelmaking slag and reducing agent, wherein the steelmaking slag is comprised of from about 20 to about 55 weight percent of calcium oxide, from about 10 to about 50 weight percent of ferrous oxide, from about 5 to about 20 weight percent of magnesium oxide, from about 5 to about 20 weight percent of silicon oxide, from 0.5 to about 10 weight per cent aluminum oxide, and from about 0.5 to about 10 weight percent of manganese oxide; and the reducing agent is comprised of from about 5 to about 80 weight percent of calcium carbide and from about 10 to about 70 weight percent of a material selected from the group consisting of silicon, titanium, silicon carbide, and mixtures thereof.
  • a slag composition comprised of steelmaking slag and from about 0.5 to about 15 percent of reducing agent by total weight of steelmaking slag and reducing agent
  • the steelmaking slag is comprised of from about 20 to about 55 weight percent of calcium oxide, from about 10 to about 50 weight percent of ferrous oxide, from about 5 to about 20 weight percent of magnesium oxide, from about 5 to about 20 weight percent of silicon oxide, from 0.5 to about 10 weight per cent aluminum oxide, and from about 0.5 to about 10 weight percent of manganese oxide
  • the reducing agent is comprised of from about 5 to about 80 weight percent of calcium carbide and from about 10 to about 70 weight percent of a first material selected from the group consisting of silicon, titanium, silicon carbide, and mixtures thereof; and from about 5 to about 80 weight percent of a second material including a fluxing material selected from the group consisting of lime, calcium aluminate, calcium silicate, glass, calcium fluoride, byproduct oxides, steelmaking slag,
  • Figure 1 is a flow chart of a preferred process for producing the desired slag.
  • Standard terminology is widely used in steel making art.
  • slag is meant to indicate a mixture of inorganic metal oxide solids within an ionic liquid usually floating upon the surface of molten steel.
  • a "fluxing agent” is a composition which enhances the dissolution rate of solid components of the slag and thereby typically increases the rate of reduction reaction by one or more reducing agents that are present in the additives of the present invention.
  • primary steelmaking refers to a process involving the production of raw liquid steel using oxygen.
  • secondary steelmaking refers to a process involving removal of dissolved oxygen and adjustment of alloy composition in the molten steel.
  • the preferred additive of this invention for making a ladle slag composition is comprised of a first reducing agent consisting of calcium carbide, a second reducing agent, and at least one fluxing agent selected from the group consisting of calcium aluminate, glass, oxides of elements of Groups IA, MA, IMA, IVA of the Periodic Table of the Elements, fluorides of elements of Groups 1 A, MA, and IMA of the Periodic Table, silicon carbide, and mixtures thereof, and from about 0 to about 10 weight percent of a metal carbonate.
  • the preferred additive is comprised of from about 5 to about 60 weight percent, by total weight of additive, of calcium carbide. It is preferred that the calcium carbide be in particulate form and that at least about 90 weight percent of its particles have a particle size in the range between from about 0.1 to about 0.7 inches. In an even more preferred embodiment, at least about 90 weight percent of the calcium carbide particles have a particle size in the range of from about 0.25 to about 0.4 inches. As used herein, particle size is meant to indicate a diameter of an approximately spherical particle, or the maximum dimension of an oblong particle.
  • from about 30 to about 50 weight percent of the calcium carbide is used in the composition of the invention.
  • commercial grade calcium carbide such as, e.g., miner's grade calcium carbide which may contain about 85 weight percent of calcium carbide.
  • miner's grade calcium carbide is sold, e.g., by Carbide International, LLC. of Louisville, Ky.
  • the preferred additive of this invention also comprises from about 10 to about
  • the second reducing agent may be comprised of silicon, titanium, or silicon carbide.
  • the additive is comprised of from about 20 to about 50 weight percent of silicon or titanium or silicon carbide.
  • the silicon used to form the additive of this invention may be pure elemental silicon. Alternatively, or additionally, it may be elemental silicon in combination with other materials (ferro-silicon, calcium silicon) or silicon carbide.
  • the titanium used to form the additive of this invention may be pure elemental titanium. Alternatively, or additionally, it may be elemental titanium in combination with other materials (ferro-titanium) or titanium carbide.
  • the second source of reducing agent used in the process of the invention is constituted, whether by itself or in admixture with other material(s)
  • the second reducing agent material have a particle size distribution such that at least about 90 weight percent of its particles have a particle size in the range between from about 0.1 to about 0.7 inches.
  • At least about 90 weight percent of the second reducing agent has a particle size in the range of from about 0.25 to about 0.4 inches.
  • the particle size distribution of the second reducing agent material must be substantially the same as the particle size distribution of the calcium carbide material. If the particle size distributions of these materials differ substantially, segregation of the particle compacts within the mixture occurs during shipment of the material, and a non- homogeneous additive is produced.
  • the calcium carbide and the second reducing agent comprise no more than about 70 weight percent of the desired additive.
  • the use of the second reducing agent in the additive of this invention is unexpectedly advantageous in that it results in slag that is more fluid and thereby increases the kinetic rates of reaction of slag reduction.
  • the reaction rate is substantially slower and all of the advantages of the additive are not achieved. This is not obvious.
  • the additive of this invention when added to the slag to be treated, undergoes an exothermic reaction which facilitates the production of the desired slag.
  • the slag to be treated may vary in composition.
  • One typical such slag contains 45 weight percent of calcium oxide, 28 weight percent of ferrous oxide (FeO), 12 weight percent of magnesium oxide, 10 weight percent of silicon oxide, and 5 weight percent of manganese oxide.
  • FeO ferrous oxide
  • MBE magnesium oxide
  • silicon oxide silicon oxide
  • manganese oxide manganese oxide
  • the additive of this invention contains from about 25 to about 30 weight percent of the second reducing agent, and from about 70 to about 75 weight percent of the aforementioned calcium carbide, by total weight of silicon, titanium and calcium carbide.
  • a flux material is added to the second reducing agent and the calcium carbide.
  • no more than about 70 weight percent of the additive is comprised of second reducing agent and calcium carbide.
  • the fluxing agent used be selected from the group consisting of calcium aluminate, glass, oxides of elements of Groups IA, MA, IMA, IVA of the Periodic Table of the Elements, fluorides of elements of Groups 1 A, NA, and IMA of the Periodic Table, silicon carbide, and mixtures thereof, and from about 0 to about 20 weight percent of a metal carbonate.
  • the additive of this invention is preferably made by dry blending the calcium carbide, the material containing the silicon and/or titanium and/or silicon carbide, and, optionally, one or more of the fluxes in the desired stoichiometry.
  • silicon carbide is used as a fluxing agent as well as a reducing agent
  • some amount of the silicon carbide forms a silicon oxide reaction product, which functions as the actual fluxing agent.
  • glass may include any complex silicate glass, such as e.g., crushed bottles or window glass.
  • the raw materials preferably contain less than about 0.2 weight percent of moisture and, if needed, are dried until the moisture content is reduced to or below this level.
  • the dried material can then be charged to a paddle mixer and dry blended. Typically, the materials are dry blended for from about 5 to about 15 minutes, depending upon the batch size. The blended materials are then discharged into shipping containers. Description of a Preferred Process for Using the Additive of this Invention
  • the present invention provides for the manufacture in situ of a ladle slag by the addition of a mixture of materials including silicon, calcium silicon and/or titanium and/or silicon carbide, calcium carbide, and, optionally, one or more fluxing materials such as glass or other complex oxides of low melting point, alkali metal salts, alkali earth metal salts, and slag raw materials containing components such as silica, calcium fluoride, alumina, lime, magnesia, and calcium aluminate which are required to achieve the desired slag composition.
  • a ladle slag in more than one step through more than one addition of mixtures of the above materials.
  • the applicant believes that when one or more fluxes are used, they dissolve the CaO and Si ⁇ 2 or Ti ⁇ 2 reaction products that form on the surfaces of the reducing agents during the reduction reaction, thereby presenting further reducing agent surfaces that may contact the slag to continue the reduction reactions.
  • the glass and calcium fluoride when used, act as fluxes, i.e., they solubilize, other ingredients.
  • Alumina, silica, calcium fluoride, and lime are slag formers. These raw materials provide the components necessary to achieve a desired composition with appropriate physical and chemical properties for steel refining in the ladle. It should be noted that each component may serve multiple functions.
  • the final slag properties and characteristics required or desired for a given ladle refining system are calculated or otherwise determined.
  • the minimum amount of required ladle slag depth is established, usually around 2 inches if no arc reheating is applied, or 4 - 6 inches if arc reheating will be applied.
  • the primary furnace slag chemistry is measured or approximated using historical and real time data.
  • the amount of this slag that is carried into the ladle is determined in two steps. First, the tendency for slag carry over is estimated based on historical data for the particular steel grade and steel making conditions, especially with regard to steel oxygen potential, duration of tapping, use of slag retention devices, condition of tap hole, etc. One may then determine the amount of ferrous oxide (FeO) and manganese oxide (MnO) in the slag to be treated which must be reduced.
  • FeO ferrous oxide
  • MnO manganese oxide
  • the tapping process is preferably observed, and the actual slag carry over quantity is measured using one or more of commercially available slag detection devices, or using visual means.
  • the excess quantities of iron and manganese oxides in the ladle slag can now be calculated, and this amount will determine the required slag reducing agent.
  • the amount of gas generation from this amount of calcium carbide is calculated, and compared with what is thought to be the maximum acceptable amount of gas generation. If the gas generation or gas generation rate are predicted to be excessive, an amount of calcium carbide is substituted by an amount of second reducing agent to provide equal reducing power but to decrease the gas generation or gas generation rate to an acceptable level (the gas generation level that is acceptable will vary by location and process).
  • the second reducing agent may be substituted for calcium carbide to achieve the desired chemistry.
  • the amount of carbon that is included in the steel when using calcium carbide slag reducing agents is preferably determined depending on process parameters and desired final FeO level. This amount of carbon pick-up will add to the existing carbon level in the steel. In some cases, the incremental carbon will create an unacceptably high carbon content of the steel. In that case, the maximum amount, or tolerance for calcium carbide slag reducing agent is calculated. The second reducing agent will then be substituted for the calcium carbide component to achieve the desired slag deoxidation.
  • calcium carbide tolerance is preferably first calculated, since calcium carbide slag reducing agents are less costly than slag reducing agents based on the second reducing agent.
  • the tolerance for calcium carbide is very low, for example in tire cord carbon steels.
  • the primary slag reducing agent is based on the second reducing agent by necessity.
  • the effectiveness of the silicon and/or titanium based reducing agents can be greatly improved by the addition of calcium carbide.
  • the calcium carbide causes agitation within the slag, thereby mixing the silicon and/or titanium based conditioner into the slag for more efficient reaction.
  • the calcium carbide's reaction products also help to dissolve the silicon and/or titanium oxide reaction products, and helps to fluidize the slag.
  • the solubility of magnesia in the final desired slag composition is determined, and that amount may be added in the form of magnesia containing materials in the slag additive.
  • the required fluxing agents are added to ensure that the lime, silica and titanium oxide reaction products generated by the reduction reactions are dissolved and that the reducing agent surface is continually available for contact with the iron and manganese oxides that are present in the slag. It will be appreciated that, when a particular step of the process calls for adding one or more fluxing agents, this step may be omitted when the desired composition does not contain such fluxing agent.
  • fluxing agents may be added such as, e.g., silica, calcium fluoride, sodium oxide, alumina, carbon, lime, magnesia, and calcium aluminate; the addition of these reagents, in some embodiments, will fulfill the requirements necessary to achieve the desired slag composition and properties. Depending upon specific conditions at each ladle refining installation, it may be appropriate to manufacture in situ a secondary slag in more than one step through more than one addition of mixtures of the above materials.
  • the slag additives of the present invention are added to the ladle during the tapping of steel, preferably approximately one-half to two-thirds through the tap, or alternatively to the top of the steel after the tap.
  • FIG. 1 is a flow diagram illustrating a preferred process of this invention.
  • a ladle 10 receives via line 12 molten steel and molten steel making slag.
  • the molten steelmaking slag generally contains from about 25 to about 55 weight percent of calcium oxide, from about 10 to about 50 weight percent of ferrous oxide (FeO), from about 5 to about 20 weight percent of magnesium oxide, from about 5 to about 20 weight percent of silicon oxide, from about 2 to about 10 weight percent alumina and from about 0.5 to about 10 weight percent of manganese oxide.
  • FeO ferrous oxide
  • the molten steel generally contains at least about 70 weight percent of molten, elemental iron and less than about 1 percent of elemental carbon dissolved therein.
  • the molten steel and the molten slag are charged in such concentrations via line 12 such that these two components comprise at least about 90 weight percent of molten steel, and more preferably, at least about 95 weight percent of molten steel.
  • the slag 16 is disposed on top of the molten steel 18, shielding it from contact with the ambient atmosphere indicated by arrow 20. It will be appreciated that, although this is generally the situation in steel making, there are instances in which the slag layer 16 does not fully cover the molten steel 18.
  • a reducing agent is added to the ladle 10 containing the molten steel 18 and the slag 16 to the ladle 10 containing the molten steel 18 and the slag 16 .
  • the reducing agent is a combination of reagents "A" and "B", to be described in detail later in this specification. However, it should be understood that the process depicted in FIG.
  • reducing agents A or B may be used with only one of reducing agents A or B, with both reducing agents A and B , with three reducing agents (not shown), etc.
  • one may supply ladle 10 via line 23 with one or more reducing agent(s) such as calcium carbide, silicon carbide, ferrosilicon, titanium, titanium carbide, ferrotitanium, calcium silicon and combinations thereof.
  • the process of this invention may be used with any or all of these reducing agents and/or other reducing agents.
  • the use of aluminum as a reducing agent is restricted due to downstream steel processing considerations.
  • FIG. 1 illustrates a preferred process, in which reducing agent A is calcium carbide, and reducing agent B is ferro-silicon. These reducing agents may be added in the desired proportion either by premixed combination or by separate proportional addition.
  • the calcium carbide is preferably used by charging miner's grade calcium carbide from hopper 22, and the ferro-silicon is preferably used by charging from hopper 24.
  • the additional fluxing agent(s) may be charged from hopper 22, where it is present in admixture with the calcium carbide material.
  • one or more of the additional fluxing agent(s) may be present in hopper 24 admixed with the silicon material.
  • all of the reagents may be present in an admixture in hopper 22, hopper 24, or another hopper (not shown)
  • valve 28 allows nitrogen to flow through pipe 26 and to entrain the materials discharged from hoppers 22 and 24, thus carrying such materials through such pipe into ladle 10.
  • controller 29 which communicates with hoppers 22 and 24 via control lines 30, 32, and 34 and controls valves 36 and 38. Controller 29 also communicates with and controls valve 28 via line 35. It is to be understood that lines 30, 32, 34, 36, 38, and 35 are typical process control communication lines, and may comprise numerous electrical wires and/or optical fibers as is known in the process control arts.
  • the controller 29 is comprised of a computer (not shown), with a microprocessor, input and output devices, and communication modules; controller 29 also includes a software program (not shown) which evaluates a multiplicity of factors in determining how much of reagent A and how much of reagent B to charge to ladle 10. The controller 29 evaluates historical data and real-time data in determining how much of each of reagents A and B to charge to the ladle 10. Referring again to FIG. 1 , it will be seen that historical data is input to controller
  • This historical data may include (but is not limited to) (1 ) the average and standard deviation of the weight of slag carried over from the furnace to the ladle 10 during previous manufacturing sessions, (2) the average weight percent of ferrous oxide and manganese oxide present in the steel making slag during previous manufacturing sessions, (3) the time required to tap the batch of steel made immediately prior to the current batch, (4) the weight of the batch of steel made during the session immediately prior to the current batch, and (5) the average final slag composition for the grade of steel being made in the current batch.
  • real time data is input to controller 29 via line 38.
  • This real time data may include (but is not necessarily limited to) one or more of such factors as (1 ) the concentration, in parts per million, of oxygen dissolved in the steel before tapping, (2) the scheduled additions planned for the batch in question by the steel mill additions programs, which often involve the addition of materials such as alloys, calcium oxide, calcium aluminate, etc., (3) the chemical analyses of the steel prior to tapping, (4) the chemical analyses of the slag prior to tapping, (5) whether a slag retention device (such as a refractory shape) is being used in the process, (6) the amount of slag which actually went into ladle 10, and (7) the temperature of the steel.
  • a slag retention device such as a refractory shape
  • camera 40 continuously monitors the tapping stream fed via line 12 for the duration of the tap and, thus, can assist the controller 29 in determining the flow rate of the steel.
  • controller 29 is programmed to calculate the amount of ferrous oxide and manganese oxide which needs to be reduced within ladle 10 in order to obtain the optimum refining slag. Based upon this calculation, the controller 29 then is capable of determining the amount of calcium-carbide containing material to be charged from hopper 22. In making such a calculation, it is desirable to note that the stoichiometric amount of calcium carbide required (3.0 moles of iron oxide per moles calcium carbide) is generally insufficient for full reduction of the iron oxide, for some of the calcium carbide is not effective.
  • controller 29 utilizes an "efficiency factor" to appropriately increase the amount of calcium carbide above the stoichiometric amount.
  • controller 29 calculates how much calcium carbide should be charged to the ladle 10 to determine whether the reaction mixture within ladle 10 can accept the presence of such an amount of calcium carbide.
  • the controller since calcium carbide contains carbon, the controller must determine how much carbon the reaction mixture in the ladle 10 can accept without compromising the quality of the steel; if too much carbon is present, it may adversely affect the properties of the steel made. The controller thus calculates how much less than the required amount of calcium carbide should be charged based upon the foaminess and carbon uptake considerations.
  • the controller can determine factors such as the concentrations of the calcium carbide and the second reducing agent materials added, and the concentration(s), if any, of the flux material(s) added.
  • the calcium carbide material and the second reducing agent material are added at or about the same time to the molten reaction mixture so that they act in concert with each other, cause an exothermic oxidation-reduction reaction to occur, and facilitate the formation of the desired refining slag.
  • the reagents added are generally present only within the slag layer 16.
  • the amount of calcium carbide in the slag layer 16 when added to the amount of second reducing agent in the slag 16, is of sufficient weight that, when such amounts are combined, they are equivalent to from about 0.5 to about 10 weight percent of the total mixture of the weights of slag on the ladle after tap, the calcium carbide added, and the second reducing agent added.
  • the presence of such reagents in the slag on the ladle 10 after tap facilitates reactions which generally produce the desired refining slag in less than about 15 minutes.
  • from about 2 to about 5 weight percent of the total mixture of slag on the ladle 10 after tap is calcium carbide and second reducing agent.
  • the calcium carbide represents from about 5 to about 60 weight percent of the total weight of these two materials, and the second reducing agent represents from about 10 to about 50 weight percent of such total weight.
  • molten steel in ladle 10 Prior to the introduction of the calcium carbide and the second reducing agent into ladle 10, molten steel in ladle 10 is generally maintained at a temperature of from about 2,600 to about 3,000 degrees Fahrenheit. After the introduction of the calcium carbide and the second reducing agent into ladle 10, it is preferred to continue maintaining the steel at such temperature of from about 2,600 to about 3,000 degrees Fahrenheit. Under such conditions, the desired refining slag is generally produced in less than about 15 minutes.
  • the fluxing agent(s) is also used in an amount such that from about 0.5 to 10 weight percent (and preferably from about 2 to 5 weight percent) of such fluxing agent is present by weight of the total weight of the slag layer 16 (which will comprise slag, calcium carbide, second reducing agent, and one or more fluxing agents).
  • fluxing agent(s) When one or more fluxing agent(s) is used, it is preferred that less than ten weight percent of the total amount of fluxing agent used is a metal carbonate. It is even more preferred that less than 5 weight percent of the fluxing agent is a metal carbonate. If a metal carbonate is used in the configuration depicted in FIG. 1 , it is preferred to charge it from hopper 24, with the second reducing agent.
  • particulate glass with a particle size substantially identical to the calcium carbide.
  • the amount of glass used is generally from about 0 to about 50 weight percent of the total amount of flux used, and preferably is from about 10 to about 30 weight percent.
  • Preferred glass compositions may include complex oxides primarily comprised of silicate, with minor amounts of calcia, alumina, magnesia, and other metal oxides; as well as calcium fluoride. Examples of suitable sources of glass materials include crushed bottles or auto glass, complex oxide industrial byproducts and by-product oxides, recycled steelmaking slag, and/or minerals such as volcanic glass. When one or more fluxing agents is used, it is preferred to also use calcium fluoride.
  • the amount of calcium fluoride used is generally from about 0 to about 30 weight percent of the total amount of flux used, and preferably is from about 10 to about 20 weight percent. When one or more fluxing agents is used, it is preferred to also use calcium oxide.
  • the amount of calcium oxide used is generally from about 0 to about 50 weight percent of the total amount of flux used, and preferably is from about 5 to about 20 weight percent.
  • silica When one or more fluxing agents is used, it is preferred to also use silica.
  • the amount of silica used is generally from about 0 to about 50 weight percent of the total amount of flux used, and preferably is from about 5 to about 20 weight percent.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Analytical Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Treatment Of Steel In Its Molten State (AREA)
  • Furnace Details (AREA)

Abstract

L'invention porte sur une composition de laitier contenant du laitier d'affinage et entre environ 0, 5 et environ 10 pour cent en poids d'un agent réducteur. Le laitier d'affinage de l'invention contient entre environ 20 et environ 55 pour cent en poids d'oxyde de calcium, entre environ 10 et environ 50 pour cent en poids d'oxyde ferreux, entre environ 5 et environ 20 pour cent en poids d'oxyde de magnésium, entre environ 5 et environ 20 pour cent en poids d'oxyde de silicium, entre 0,5 et environ 10 pour cent en poids d'oxyde d'aluminium, et entre environ 0,5 et environ 10 pour cent en poids d'oxyde de manganèse. L'agent réducteur contient entre environ 5 et environ 80 pour cent en poids de carbure de calcium et entre environ 10 et environ 70 pour cent en poids d'un mélange contenant du silicium ou du titane ou du carbure de silicium ou des combinaisons desdits éléments.
PCT/US2006/060003 2005-10-17 2006-10-16 Composition destinée à réduire le laitier d'affinage WO2007102881A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US11/251,708 US20070084306A1 (en) 2005-10-17 2005-10-17 Composition for reducing steelmaking slag
US11/251,708 2005-10-17

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WO2007102881A2 true WO2007102881A2 (fr) 2007-09-13
WO2007102881A3 WO2007102881A3 (fr) 2008-08-28

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Cited By (1)

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CN103146877A (zh) * 2013-02-04 2013-06-12 安徽省繁昌县皖南阀门铸造有限公司 一种含有竹炭的炼钢精炼剂及其制备方法

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US7914602B1 (en) 2009-12-02 2011-03-29 Carbide Industries, LLC Process to reduce steel furnace slag carry-over during tapping
KR101952894B1 (ko) * 2018-07-13 2019-02-28 한국건설기술연구원 정제 서냉 슬래그를 이용한 아스팔트 혼합물의 박리방지제, 그 제조방법, 이를 포함하는 아스팔트 혼합물 및 그 제조방법
CN109402420B (zh) * 2018-10-29 2021-03-26 昆明理工大学 一种利用含钛高炉渣制备钛硅和铝硅合金的方法
EP3670677A1 (fr) * 2018-12-17 2020-06-24 S.A. Lhoist Recherche Et Developpement Procédé de fabrication d'un agent de conditionnement de laitier pour la désulfuration d'acier
US20220364200A1 (en) * 2019-03-27 2022-11-17 The Governing Council Of The University Of Toronto Methods for recovering a target metal from iron or steel slag using at least one of a carbothermic reduction process and a pyro-hydrometallurgical process
CN110257641A (zh) * 2019-06-20 2019-09-20 昆明理工大学 一种利用含钛渣和废铝合金制备硅基材料和低Fe共晶Al-Si合金的方法
CN111922045A (zh) * 2020-08-07 2020-11-13 北京瑞思达化工设备有限公司 一种从废渣中回收矽铁的工艺
CN113502377B (zh) * 2021-08-13 2023-03-31 马鞍山钢铁股份有限公司 钢包顶渣快速还原剂及其制备方法和使用方法

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US6267798B1 (en) * 2000-02-02 2001-07-31 Nuflux, Llc Composition for treating steel making slags

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US5946339A (en) * 1997-07-22 1999-08-31 Itz A Gaz, Inc. Steelmaking process using direct reduction iron
US6267798B1 (en) * 2000-02-02 2001-07-31 Nuflux, Llc Composition for treating steel making slags

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103146877A (zh) * 2013-02-04 2013-06-12 安徽省繁昌县皖南阀门铸造有限公司 一种含有竹炭的炼钢精炼剂及其制备方法

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WO2007102881A3 (fr) 2008-08-28

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