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

Definitions

• the invention relates to a mixture comprising magnesium, carbon and aluminum for introduction into the slag present on a molten metal in iron and steel metallurgy, to the use of such a mixture and to a method for conditioning a metallurgical one in iron and steel metallurgy on a molten metal Container, for example in a converter, in an electric arc furnace or in a pan, slag.
• the pig iron melt is separated from unwanted components before it is cast.
• the crude steel melt is produced by the melting of scrap, pig iron, molten iron and / or sponge iron and other raw materials.
• the slag must be specifically influenced or conditioned with regard to chemical and physical properties.
• the basicity ie the mass or molar ratio of the basic components to the other components of the slag (which can be calculated, for example, according to the following formula: [xCaO + MgO] / [xSiO 2 + Al 2 O 3 + other components])
• the first acidic or non-basic slag are increased to the corrosive attack of the slag on the basic delivery of the metallurgical vessel, in the the molten metal is to reduce and thereby reduce the wear of the delivery and to increase their service life.
• slag conditioners have a component that increases the basicity of the slag, in particular lime, dolomitic lime or dolomite.
• the viscosity of the slag may be desirable to adjust the viscosity of the slag by the slag conditioner.
• the viscosity of the slag during refining is as low as possible in order to be able to incorporate the iron companion oxidized by the applied oxygen well into the slag.
• This applied slag layer a corrosive attack of a molten metal can be reduced to the delivery of the converter.
• the process of applying the slag to the converter is also referred to as "maintenance" of the converter.
• the foamed slag has insulating properties, so that the heat losses from the melt can be reduced and energy can be saved. Furthermore, components of the metallurgical vessel in which the molten iron is located can be protected from heat radiation by the foamed slag.
• the object of the invention is to provide a slag conditioner by means of which the basicity and the MgO content of the slag can be increased rapidly in order to prevent the slag from attacking the refractory lining of the metallurgical vessel, in which the slag conditioner Molten metal with the slag on it is able to reduce.
• a further object of the invention is to provide a slag conditioner by means of which the viscosity of the slag can be adjusted in a targeted manner.
• Another object of the invention is to provide a slag conditioner by which foaming of the slag can be achieved.
• a further object of the invention is to provide a slag conditioner by which an increase in the iron yield of the primary metallurgical process can be achieved.
• a mixture or a slag conditioner for introduction into the slag contained in a molten metal in iron and steel metallurgy, the mixture comprising magnesium, carbon and aluminum in the following proportions by mass: MgO: 45-90% by mass; C: 5-40 mass%; and Al 2 O 3 : 1-20 mass%.
• the mixture according to the invention or the slag conditioner according to the invention is suitable for introduction into slags on molten metals in any metallurgical vessel, but in particular for slags in converters, electric arc furnaces and ladles.
• magnesium and aluminum in the mixture according to the invention are given as fractions of their oxides MgO and Al 2 O 3 in the mixture, as usual in refractory technology.
• magnesium and especially aluminum may also be used as described herein other than in oxide form in the mixture according to the invention, for example in metallic form or, with regard to aluminum, in the form of carbide.
• the proportion of MgO in the mixture according to the invention By the proportion of MgO in the mixture according to the invention, the MgO saturation of the slag is reached faster, so that the corrosive attack of the slag is reduced to the refractory lining of the metallurgical vessel holding the molten metal. Furthermore, the viscosity of the slag increases with increasing MgO content.
• Magnesium is preferably present in the mixture according to the invention as an oxide, ie in the form of MgO.
• the proportions of magnesium in the mixture according to the invention are preferably exclusively in the form of MgO, particularly preferably in the form of sintered or fused magnesia.
• MgO can be present in the mixture according to the invention in proportions of at least 45% by mass, that is also for example in proportions of at least 48, 50, 52, 54, 56, 57, 58, 59, 60 or 61% by mass. Furthermore, MgO may be present in the mixture in proportions of at most 90% by weight, that is to say, for example, in proportions of at most 88, 86, 84, 82, 80, 78, 76, 74, 72, 70, 69, 68, 67, 66 , 65, 64 or 63% by mass.
• the proportion of carbon of the mixture according to the invention reacts when entering the mixture into the slag with oxygen in the slag to form carbon oxides, in particular to carbon monoxide CO and carbon dioxide CO 2 .
• the carbon of the mixture oxidizes immediately and violently with oxygen fractions of the slag, so that it foams spontaneously when introducing the mixture.
• the slag thus rises, as in slag-foaming, in the air and covers the refractory lining of the metallurgical vessel.
• the Electric arc furnace is shielded by the increased volume of the foamed slag, the radiation of the arcs partially or completely with respect to the furnace wall. Due to the increased content of MgO, the slag simultaneously obtains the necessary viscosity in order to adhere to the wall during and after foaming.
• the carbon of the mixture can react directly with oxygen of the molten metal and extract oxygen from the molten metal.
• This extracted from the molten metal oxygen must not be removed later in additional steps by deoxidizer, such as aluminum, from the molten metal.
• At least part of the oxygen with which the carbon introduced into the slag from the mixture according to the invention reacts originates from iron oxides in the slag, which are reduced by the carbon to metallic iron.
• iron oxides are fluxes which reduce the viscosity of the slag.
• the viscosity of the slag can be increased.
• the yield of recovered iron is increased in the overall process.
• Due to the proportion of carbon in the mixture can thus be achieved on the one foaming of the slag. Furthermore, the viscosity of the slag can be increased. By the proportion of carbon in the mixture can thus be adjusted in a targeted manner the extent of foaming of the slag and its viscosity.
• the carbon in the mixture, can be present substantially in pure form, for example in the form of graphite or coke, but also, for example, communitized with other constituents, for example with aluminum fractions or magnesium fractions of the mixture.
• the proportions of carbon according to the invention in the mixture is present partially, substantially or even completely in the form of aluminum carbide (Al 4 C 3 ).
• Carbon is present in the mixture according to the invention in proportions of at least 5% by mass, for example also in proportions of at least 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 , 20, 21, 22 or 23 mass%. Furthermore, carbon is present in the mixture according to the invention in proportions of at most 40% by mass, ie for example also in proportions of at most 38, 36, 34, 32, 31, 30, 29, 28, 27, 26 or 25% by mass.
• Aluminum calculated as Al 2 O 3
• Aluminum can be present in a proportion of at least 1% by mass in the mixture, ie also in a proportion of at least 2, 3, 4 or 5% by mass. Further, aluminum, calculated as Al 2 O 3, present at levels of at most 20 mass% in the mixture, thus for example also in proportions of at most 18, 16, 14, 13, 12, 11, 10, 9, 8 or 7 Dimensions-%.
• the proportion of aluminum in the mixture according to the invention is herein calculated as Al 2 O 3 , although the proportions of aluminum in the mixture preferably not in oxide form as Al 2 O 3 , but preferably partially, substantially or completely in metallic form and / or in the form of carbide, ie as Al 4 C 3 .
• this aluminum carbide simultaneously forms a carrier of both the aluminum and the carbon content in the mixture.
• the aluminum carbide component is particularly advantageous insofar as both the aluminum and the carbon of the aluminum carbide can react with oxygen fractions of the slag and thereby reduce oxidic constituents of the slag, in particular iron oxides can be. With corresponding reactions, the aluminum content of the aluminum carbide oxidizes to Al 2 O 3 and the carbon content of the aluminum carbide to CO 2 .
• slag conditioners include magnesium, they have this regularly in the form of magnesium carbonate (MgCO 3 ), dolomite or partially in the form of magnesium hydroxide (Mg (OH) 2 ).
• MgCO 3 magnesium carbonate
• dolomite magnesium hydroxide
• Mg (OH) 2 magnesium hydroxide
• the mixture according to the invention in contrast to the prior art, is formulated such that the component comprising magnesium, in particular in the form of MgO, is provided solely for increasing the basicity and the MgO content in the mixture, while the foaming of the slag by other components the mixture is caused, in particular by the components comprising carbon and aluminum.
• the resource efficiency is higher, that is, the specific consumption and the total weight of slag conditioner to be introduced and transported into the slag is lower than in the prior art.
• the emissions of carbon dioxide can be reduced by the slag conditioner according to the invention, as far as carbonate-containing slag formers are replaced by the slag former according to the invention.
• the mixture has a proportion of magnesium carbonate of less than 10% by mass, that is to say, for example, a proportion of less than 9, 8, 7, 6, 5, 4, 3, 2, 1 or 0.5% by mass.
• the mixture has a content of Mg (OH) 2 of less than 10% by mass, that is to say for example also a fraction of 9, 8, 7, 6, 5, 4, 3, 2, 1 or 0.5 Dimensions-%.
• the mixture has a proportion of dolomite, in particular of crude dolomite, less than 10% by mass, so for example, a proportion of 9, 8, 7, 6, 5, 4, 3, 2, 1 or 0.5 mass%.
• the mixture has a proportion of calcium carbonate or of limestone below 10% by mass, ie, for example, a proportion of 9, 8, 7, 6, 5, 4, 3, 2, 1 or 0.5 mass -%.
• the mixture is present in a relatively small particle size, for example at least 70% by mass, 80% by mass or at least 90% by mass or else 100% by mass in a particle size of less than 0.5 mm.
• the mixture according to the invention can meet, for example, only one of the following conditions in terms of particle size: ⁇ 1 mm: 100% by mass; ⁇ 500 ⁇ m: 100% by mass; ⁇ 315 ⁇ m: at least 90 or 95% by mass and at most 100% by mass; ⁇ 200 ⁇ m: at least 85 or 90% by mass and at most 95 or 100% by mass; ⁇ 100 ⁇ m: at least 65 or 70% by mass and at most 75 or 80% by mass; ⁇ 63 ⁇ m: at least 45 or 50% by mass and at most 65 or 70% by mass.
• the mixture according to the invention having this very small average particle size, it is possible to effect a particularly good and uniform distribution and, in particular, rapid dissolution of the mixture in a slag.
• a mixture according to the invention which in particular can have the previously described particle size distribution, is pressed into pellets without additions of additives.
• these pellets may have an almond-shaped, rod-shaped or spherical shape, for example with a maximum length of, for example, 50 mm, 40 mm or 30 mm.
• the pellets may also have, for example, a minimum diameter of 5, 10, 15, 20 or 25 mm.
• the mixture according to the invention has a proportion of calcium oxide (CaO), as by this the basicity of the slag can be further increased and the attack of the slag can be reduced to the refractory lining of the metallurgical vessel.
• the CaO of the mixture has, in particular, an advantageous basicity-reducing effect if the ratio of CaO to SiO 2 in the mixture does not exceed a certain level.
• the basicity of the slag can be increased by the CaO, in particular, if the ratio of mass fractions of CaO to SiO 2 in the mixture is not less than 0.7. It can therefore be provided that the ratio of the mass fractions of CaO to SiO 2 in the mixture according to the invention is not less than 0.7.
• SiO 2 can essentially be introduced into the mixture according to the invention via impurities in the raw materials of the mixture according to the invention.
• CaO can be present in proportions of at least 0.1 or 0.2 or 0.5 or 1 or 1.5 or 2% by mass in the mixture and, for example, in proportions of at most 10, 9, 8, 7, 6, 5, 4, 3 or 2.5 mass%.
• SiO 2 can be present in the mixture in proportions of at least 0.1 or 0.2 or 0.5 or 1 or 1.5 or 2 mass% and, for example, in proportions of at most 7, 6, 5, 4, 3 or 2.5% by mass.
• the mixture in the form of pellets, wherein the mixture is compressed into pellets without the addition of additives.
• additives are used to compress the mixture into pellets
• the mixture may be envisioned to use CaO as such a pressing additive.
• the mixture contrary to the previously disclosed concept of the invention, according to which the mixture has proportions of CaO of at most 10% by mass of CaO, may have proportions of CaO of up to 40% by mass.
• the mixture preferably has no additive for pressing, so that the proportion of CaO in the mixture, as stated above, is not more than 10% by mass.
• Iron oxide stands for the sum of all iron oxides in the mixture, ie in particular FeO and Fe 2 O 3 , but also, for example, Fe 3 O 4 and Fe 2 O.
• Iron oxides may also be present in the mixture in proportions of at least 0.1% by mass, 0.2% by mass, 0.4% by mass, 0.6% by mass or 0.8% by mass, for example at most in Proportions of 7 mass%, 6 mass%, 5 mass%, 4 mass%, 3 mass%, 2.8 mass%, 2.6 mass%, 2.4 mass%, 2, 2% by mass or 2% by mass.
• the mixture comprises, in addition to the aforementioned components, ie MgO, C, Al, Al 4 C 3 , CaO, SiO 2 , iron oxides and optionally Al 2 O 3 only small proportions of other components, for example in proportions below 5% by mass, 4% by mass, 3% by mass, 2.5% by mass, 2% by mass, 1.5% by mass or else less than 1% by mass.
• the aforementioned components ie MgO, C, Al, Al 4 C 3 , CaO, SiO 2 , iron oxides and optionally Al 2 O 3 only small proportions of other components, for example in proportions below 5% by mass, 4% by mass, 3% by mass, 2.5% by mass, 2% by mass, 1.5% by mass or else less than 1% by mass.
• the mixture comprises fractions of the following components below the mass fractions indicated below: Cr 2 O 3 : ⁇ 0.2% by mass; P 2 O 5 : ⁇ 0.2% by mass; TiO 2 : ⁇ 0.2% by mass; K 2 O + Na 2 O: ⁇ 0.5 mass%; ZrO 2 : ⁇ 0.2 mass%.
• magnesia-carbon products which have been used in the steel industry, in particular as wear linings of oxygen blowing converters, in electric arc furnaces or in pans, are partly suitable as raw material for the mixture according to the invention.
• correspondingly recycled magnesia-carbon products can be used partially, largely or exclusively as raw material for the mixture according to the invention.
• the invention also relates to the use of recycled gastric carbon products as raw material for the mixture according to the invention or the use of such recycled magnesia-carbon products as inventive slag conditioners.
• magnesia in particular sintered magnesia
• carbon in particular graphite
• corundum aluminum carbide
• the mixture may, as described herein, be provided, for example, in compacted or compressed form, for example in the form of pellets.
• the mixture provided is added to the slag and sinks into it so that it can unfold its effect there according to the invention.
• the mixture according to the invention is fundamentally suitable as a slag conditioner for slags on a molten metal in any metallurgical vessel, for example for molten metals in converters, electric arc furnaces or ladles.
• the mixture according to the invention is particularly preferably used as a slag conditioner for slags on molten metals which are located in a metallurgical vessel with a basic feed, ie in particular with a feed based on at least one of the following materials: magnesia, magnesia-carbon, doloma or dolomite. Carbon.
• the invention furthermore relates to the use of a mixture according to the invention described herein for conditioning a slag present in iron and steel metallurgy on a molten metal in a metallurgical vessel.
• a mixture which comprises magnesium, carbon and aluminum as well as further components in the proportions by mass according to Table 1.
• Table 1 component Mass shares [%] MgO 62.6 C 24.6 Al 2 O 3 6.4 CaO 2.4 SiO 2 2.3 Fe 2 O 3 1.3 Cr 2 O 3 0.05 P 2 O 5 0.08 TiO 2 0.08 K 2 O 0.05 Na 2 O 0.08 ZrO 2 0.06
• the carbon was present in the mixture in the form of graphite and aluminum carbide.
• Aluminum was present in the mixture in the form of metallic aluminum and in the form of aluminum carbide.
• the raw materials used were exclusively recycled magnesia-carbon products.
• the mixture was provided in the form of almond-shaped pellets having a thickness of about 15 mm and a length of about 30 mm pressed without additional additives.
• the particle size distribution of the mixture in the pellets is given in Table 2.
• the mixture was used as a slag conditioner for a slag on a molten metal in an oxygen converter.
• the mixture was applied to the slag contained on the melt.
• its basicity could be increased.
• by the proportions of carbon, aluminum and aluminum carbide in the mixture foaming of the slag could be achieved.
• the viscosity of the slag could be adjusted to the desired level.

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• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Carbon Steel Or Casting Steel Manufacturing (AREA)
• Treatment Of Steel In Its Molten State (AREA)

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• 2013
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  • 2013-12-02 ES ES13195334.1T patent/ES2559024T3/es active Active
  • 2013-12-02 SI SI201330101T patent/SI2878685T1/sl unknown
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• 2014
  • 2014-10-01 CN CN201480062204.6A patent/CN105705662A/zh active Pending
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• 2015
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