WO2015082093A1

WO2015082093A1 - Mixture, use of this mixture and process for conditioning a slag located on a metal melt in a metallurgical vessel in iron and steel metallurgy

Info

Publication number: WO2015082093A1
Application number: PCT/EP2014/071022
Authority: WO
Inventors: Alexander Cepak; Thomas Kollmann; Oliver Zach; Marcus Kirschen
Original assignee: Refractory Intellectual Property Gmbh & Co. Kg
Priority date: 2013-12-02
Filing date: 2014-10-01
Publication date: 2015-06-11
Also published as: ES2559024T3; RS54471B1; SI2878685T1; PT2878685E; US20160376672A1; MX2016005055A; EP2878685B9; HUE026614T2; EP2878685A1; HRP20151446T1; CN105705662A; EP2878685B1; PL2878685T3

Abstract

The invention relates to a mixture comprising magnesium, carbon and aluminium to be introduced into the slag located on a metal melt in iron and steel metallurgy, to the use of such a mixture and also to a process for conditioning a slag located on a metal melt in a metallurgical vessel, for example in a converter, in an electric arc furnace or in a ladle, in iron and steel metallurgy.

Description

Mixture, use of this mixture and method for

Conditioning of a slag in iron and steel metallurgy on a molten metal in a metallurgical vessel

Description

The invention relates to a magnesium, carbon and aluminum

Comprehensive mixture for incorporation into iron and steel

Steel metallurgy on a molten metal slag, the

Use of such a mixture and a method for

Conditioning one in iron and steel metallurgy on one

Molten metal in a metallurgical vessel, for example in a converter, in an electric arc furnace or in a pan, slag.

In steel and iron metallurgy, the pig iron melt is separated from unwanted components before it is cast.

As far as a converter is used, in the LD method most widely used today, acid is applied by means of a lance to the in inflated molten pig iron contained in a converter supplied with a basic refractory material. The process of this inflation of oxygen on the pig iron melt is also referred to as fresh. When fresh iron companion, especially iron companion in the form of carbon, manganese, silicon and phosphorus are oxidized by the injected oxygen and form together with added quicklime on the molten metal floating slag layer.

In the electric arc furnace, the crude steel melt is produced by the melting of scrap, pig iron, molten iron and / or sponge iron and other raw materials.

After the molten in the primary metallurgical aggregate molten metal has the desired properties, this is the

secondary metallurgical treatment tapped through the tapping channel in the pan.

The slag must be specifically influenced or conditioned with regard to chemical and physical properties.

For conditioning the paints, it is known to use the slag

To provide so-called slag conditioners to change the properties of the slag can.

Thus, the basicity, ie the mass or molar ratio of the basic components to the other components of the paints (which can be calculated, for example, according to the following formula: [xCaO + MgO] /

[xSi0 ₂ + Al ₂ 0 ₃ + other components]), which are initially acidic or non-basic S chlacke be 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. For this purpose, slag conditioners have a component that increases the basicity of the slag, in particular lime, dolomitic lime or dolomite.

In addition, it is useful to adjust the content of MgO in the paints by adding a paint conditioner such that it is in the range of saturation of MgO in the slag and thus a corrosive attack of the slag on the feed is reduced.

Furthermore, it may be desired to increase the viscosity of the slag through the

Set slag conditioner. Thus, it is often desired that the viscosity of the paints while freshening is as low as possible in order to be able to incorporate the iron companion oxidized by the applied acid well into the slag. Furthermore, it may be desired during tapping or after tapping that the slag has a high viscosity in order to better apply the slag remaining after tapping in the converter to the refractory lining of the converter. Through this applied S chlackenschicht can be a corrosive attack a

Metal melt can be reduced to the delivery of the converter. The process of applying the slag to the converter is also called

Called "maintenance" of the converter. In the known methods for the maintenance of the converter is on the one hand to the so-called "slag-washing", in which the slag is distributed by pivoting the converter on the tapping and Chargierseite. Another method of care is the so-called "Slag-Splashing", in which the S chlacke using a nitrogen gas stream of a lance is mechanically sprayed. Finally, in the so-called "slag-foaming" slag is chemically foamed by adding a carbon carrier. The slag foaming foamed slag is also called "slag slag". In addition to the maintenance of the converter by the slag, this has further advantageous effects. Thus, the slag has insulating properties

Characteristics, so that the heat loss from the melt can be reduced and energy saved. Furthermore, components of the

metallurgical vessel, in which the molten iron is, are protected by the foam slag from heat radiation.

In order to produce a foamed slag in the electric arc furnace, additionally injected into the slag carbon is burned by means of oxygen to carbon monoxide and the foaming necessary for S

Carbon monoxide gas provided in such a way. In the case of the melting process in the electric arc furnace, foaming of the slag layer is

Significance, as this shields the arc by increasing the volume, reduces radiation losses on the furnace wall, improves the energy transfer to the melt and thus energy is saved.

Against this background, 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 on it

Slag is able to reduce.

Another object of the invention is to provide a

To provide slag conditioner available by which the viscosity of the slag can be adjusted specifically. Another object of the invention is to provide a

To provide slag conditioner by the one

Foaming of the paints can be achieved.

Finally, another object of the invention is to provide a

To provide slag conditioners that can be used to increase the iron output of the primary metallurgical process.

To achieve this object, according to the invention, a mixture or a chelate conditioner is provided 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 to 90% by mass;

C: 5 -40% by mass; and

A1 ₂ 0 ₃ : 1 -20% by mass.

The mixture according to the invention or the slag conditioner according to the invention is suitable for introduction into slags

Metal melts in any metallurgical vessel, in particular for slags in converters, electric arc furnaces and pans.

All of the statements made herein in% are in mass%, in each case based on the total mass of the mixture according to the invention.

The proportions of magnesium and aluminum in the inventive

Mixtures are given as proportions of their oxides MgO and Al ₂ O ₃ in the mixture, as usual in refractory technology. However, you can

Magnesium and especially aluminum also as set forth 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.

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 present exclusively in the form of MgO, particularly preferably in the form of sintered or semi-molten 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 mass, ie

for example, also in proportions of not more than 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 in the S chlacke with oxygen located in the S chlacke to carbon oxides, in particular to carbon monoxide CO and carbon dioxide C0 _second When the mixture is introduced into the paints, the carbon of the mixture is oxidized promptly and vigorously with acid constituents of the slag, so that it spontaneously foams when the mixture is introduced. The slag thus rises, as in slag-foaming, in the air and covers the refractory lining of the metallurgical vessel. in 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.

As far as the mixture comes into direct contact with the molten metal, for example because it passes through a dishwasher to an opening of the

Slag layer comes, the carbon of the mixture can react directly with oxygen of the molten metal and withdraw 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 acid with which the carbon introduced from the mixture according to the invention into the paints reacts originates from iron oxides in the slag, which are reduced by the carbon to metallic iron. Iron oxides, in contrast to metallic iron, however, are fluxes which reduce the viscosity of the paints.

By the proportion of iron oxides in the slag by the addition of

Mixture is reduced, thus the viscosity of the slag can be increased. Furthermore, 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 the S chlacke. Furthermore, the viscosity of the slag can be increased. By the proportion of carbon in the

Mixture thus the extent of foaming of the slag and their viscosity can be adjusted specifically. In the mixture, the carbon may 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 content or magnesium content of the mixture. In particular, it can be provided that the proportions of carbon according to the invention in the mixture partially, substantially or completely in the form of

Aluminum carbide (Al ₄ C ₃ ) is present.

Carbon is present in the mixture according to the invention in proportions of at least 5% by mass, ie for example also in fractions 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 , in a proportion of at least

1% by mass) in the mixture, that is, for example, in a proportion of at least 2, 3, 4 or 5% by mass. Furthermore, aluminum, calculated as Al ₂ O ₃ , may be present in proportions of not more than 20% by mass in the mixture, that is to say for example also in proportions of at most 1 8, 16, 14, 13, 12, 11, 10, 9, 8 or 7% by mass.

The proportion of aluminum in the mixture according to the invention is herein, as stated above, calculated as Al ₂ O ₃ , wherein the inventive proportions of aluminum in the mixture j edoch preferably not in oxide form as Al ₂ O ₃ , but preferably partially, substantially or also completely in metallic form and / or in the form of carbide, ie as Al ₄ C ₃ . As far as aluminum is present as carbide in the mixture, this forms

Aluminum carbide at the same time a carrier of both the proportion of aluminum and the carbon in the Mis monitoring.

As far as carbon and aluminum in the mixture in the form of

Aluminum carbide present, the aluminum carbide component is particularly advantageous insofar as that both the aluminum and the

Carbon of the aluminum carbide can react with the acid constituents of the slag and, as a result, oxidic constituents of the slag, in particular iron oxides, can be reduced. With corresponding reactions, the aluminum content of the aluminum carbide oxidizes to A1 ₂ 0 ₃ and the carbon content of the aluminum carbide to C0 ₂ .

As far as slag conditioner according to the prior art

Magnesium shares include, they have this regularly in the form of

Magnesium carbonate (MgC0 ₃ ), dolomite or partially in the form of magnesium hydroxide (Mg (OH) ₂ ) on. In that regard, it is considered advantageous according to the prior art that upon contact of these components of the relevant slag conditioner with the slag the

Magnesium carbonate in magnesium oxide and carbon dioxide, the dolomite in magnesium and calcium oxide and carbon dioxide or magnesium hydroxide is split into magnesium oxide and water vapor. The carbon dioxide and the steam cause foaming of the slag.

According to the invention, however, it has been found that in the form of

Magnesium carbonate, dolomite or magnesium hydroxide present

Magnesium only lead to a delayed increase in the basicity and the MgO content of the S chlacke. Furthermore, it has been found according to the invention that the basicity and the MgO content of the slag are substantially faster and can be increased more effectively by adding magnesium in the form of magnesium oxide in the S chlacke. In that sense, the

Compared to the prior art, the mixture according to the invention is formulated in such a way 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 is caused by other components of the mixture in particular by the components comprising carbon and aluminum. Furthermore, as no further carbonates have to be introduced into the primary metallurgical process by the slag conditioner according to the invention, the resource efficiency is higher, that is to say the specific consumption and the total weight to be introduced and transported into the slag

Slag conditioner lower than in the prior art. In addition, the emissions of carbon dioxide by the inventive

Slag conditioning is reduced, as far as carbonate

Schlackenbildner be replaced by the slag forming agent according to the invention.

According to the invention, it may be provided that the mixture has a proportion of magnesium carbonate of less than 10% by weight, that is to say, for example, a proportion of less than 9, 8, 7, 6, 5, 4, 3, 2, 1 or 0.5 mass%. %.

Furthermore, it can be provided that 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% by mass.

Furthermore, it can be provided that the mixture has a proportion of dolomite, in particular of crude dolomite, below 10 mass%>, ie

for example, a proportion of 9, 8, 7, 6, 5, 4, 3, 2, 1 or 0.5% by mass. Furthermore, it can be provided that the mixture accounts for a share

Calcium carbonate or limestone less than 10% by mass, ie, for example, a proportion of 9, 8, 7, 6, 5, 4, 3, 2, 1 or 0, 5% by mass.

It is preferably provided that 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 below 0, 5 mm.

For example, it may be provided that the particle size of the components of the mixture according to the invention is present below the particle sizes indicated below in the proportions by weight given in each case, it also being possible for the mixture according to the invention, for example, to fulfill only one of the following conditions with respect to its particle size:

<1 mm: 100 mass%>;

<500μιη: 100 mass%;

<3 15 μιη: at least 90 or 95 mass%> and at most 100 mass%>;

<200μιη: at least 85 or 90 mass%> and at most 95 or 100

Dimensions-%;

<Ι ΟΟμιη: at least 65 or 70 mass%> and not more than 75 or 80 mass%

<63 μιη: at least 45 or 50 mass%> and at most 65 or 70 mass%

When the mixture according to the invention has this very low mean particle size, it is possible to effect a particularly good and uniform distribution and, in particular, rapid dissolution of the mixture in a slag. In order to be able to achieve good handling of the mixture according to the invention in spite of this small particle size of the mixture, it can be provided to provide the mixture in compacted or pressed form, for example in the form of pellets. In order to provide the mixture in the form of pellets, it can be provided that 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.

For example, 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. Pellets of an appropriate size are easy to handle, but at the same time still so small that they quickly disintegrate there after being introduced into a slag and the advantages of the invention are minimal

Grain size distribution can take effect there quickly.

It can be provided that the mixture according to the invention has a proportion of calcium oxide (CaO), since by this the basicity of the slag can be further increased and the attack of S chlacke can be reduced to the refractory lining of the metallurgical vessel. The CaO of the mixture has, in particular, an advantageous basicity-reducing effect when the ratio of CaO to Si0 ₂ in the mixture

does not exceed a certain level.

According to the invention, it has been found that the basicity of the slag can be increased by the CaO, in particular, if the ratio of mass fractions of CaO to Si0 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 Si0 ₂ in the mixture according to the invention is not less than 0.7. Si0 ₂ can essentially be reached by impurities of the raw materials of the mixture according to the invention in this.

It can be provided that the mixture comprises calcium oxide and silicon dioxide in the following proportions by weight:

CaO: 0 to 10 mass%,

Si0 ₂ : 0 to 7 mass%.

CaO can furthermore be present, for example, in proportions of at least 0, 1 or 0.2 or 0.5 or 1 or 1, 5 or 2% by weight in the mixture, and

for example, in proportions of at most 10, 9, 8, 7, 6, 5, 4, 3 or 2.5% by mass.

Si0 ₂ may be present, for example, 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 7, 6, 5, 4, 3 or 2.5 mass%>.

As stated above, it can be provided to provide the mixture in the form of pellets, wherein the mixture is compressed into pellets without the addition of additives. However, as far as additives for pressing the mixture into pellets are used, it may be provided to use CaO as such a pressing additive. In this case, 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. However, 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 weight. It can be provided that the mixture contains iron oxides in the following

Mass fractions includes:

Iron oxide: 0 to 7% by mass.

Iron oxide stands for the sum of all iron oxides in the mixture, ie in particular FeO and Fe ₂ 0 ₃ , but for example Fe ₃ 0 ₄ and Fe ₂ 0.

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) and for example at most in proportions of 7% by mass, 6% by mass, 5% by mass, 4% by mass, 3% by mass, 2.8% by mass, 2.6% by mass, 2.4% by mass, 2.2 mass% or 2 mass%.

According to the invention, it has been found that the advantageous effects of the mixture according to the invention described herein as

Slag conditioners can be adversely affected by the presence of other components in the mixture.

It can therefore be provided that the mixture in addition to the aforementioned components, ie MgO, C, Al, Al ₄ C ₃ , CaO, Si0 ₂ , iron oxides and

if appropriate A1 ₂ 0 ₃ comprises only small proportions of further components, for example in proportions of less than 5% by weight, 4% by weight, 3% by weight, 2.5% by weight, 2% by weight, 1, 5 mass%> or less than 1 mass%>.

For example, it may be provided that the mixture contains proportions of the following components below the below

Mass shares includes:

Cr ₂ 0 ₃ : <0.2% by mass;

P ₂ 0 ₅ : <0.2% by mass;

Ti0 ₂ : <0.2 mass%; K ₂ O + Na ₂ O: <0.5 mass%;

Zr0 ₂ : <0.2 mass%.

Surprisingly, it has been found according to the invention that

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 in part suitable as raw material for the mixture according to the invention. In this respect, correspondingly recycled magnesia-carbon products can be used partially, largely or exclusively as raw material for the mixture according to the invention.

In this respect, the invention also relates to the use of recycled gastric carbon products as a raw material for the mixture according to the invention or the use of such recycled magnesia-carbon products as inventive shell conditioners.

For example, it may be provided to select as raw materials for the mixture according to the invention in addition to recycled magnesia-carbon products at least one of the following further raw materials: magnesia (especially sintered magnesia), carbon (especially graphite), corundum or

Aluminum carbide.

The invention furthermore relates to a method for conditioning a slag contained in a metallurgical vessel during iron and steel metallurgy, comprising the following steps:

Providing a herein described, according to the invention

Mixture;

Introducing the mixture into the molten metal in the

metallurgical vessel located S chlacke. 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 suitable in principle as

Slag conditioner for slag on a molten metal in any metallurgical vessel, for example for molten metals in converters, electric arc furnaces or pans. The mixture according to the invention is particularly preferably used as a slag conditioner for thin paints on metal melts which are 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 doloma -Carbon.

The invention further relates to the use of a herein

described mixture according to the invention for conditioning a in the iron and steel metallurgy on a molten metal in one

metallurgical vessel slag.

The use can be carried out as disclosed herein.

All of the features of the invention disclosed herein may be combined with each other singly or in combination.

The invention will be explained in more detail with reference to the following embodiment. First, a mixture was made available in the embodiment, the magnesium, carbon and aluminum and others

Components in the mass proportions according to Table 1 includes.

Table 1

The carbon was in the mixture in the form of graphite as well

Aluminum carbide ago.

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.

Table 2

The mixture was used as a slag conditioner for a slag on a molten metal found in an acid converter. The mixture was on the slag on the melt

given up. By adding the mixture to the paints, their basicity could be increased. Furthermore, by the proportions of carbon, aluminum and aluminum carbide in the mixture foaming of the slag could be achieved. Finally, the viscosity of the slag could be adjusted to the desired level.

Claims

P at e n t p o rt e s

Mixture for incorporation into the slag on a molten metal found in iron and steel metallurgy, magnesium,

Comprising carbon and aluminum in the following proportions by weight: MgO: 45 to 90% by mass;

C: 5 to 40 mass%;

A1 ₂ 0 ₃ : 1 to 20% by mass.

Mixture according to claim 1 with a content of MgC0 ₃ below

10% by mass.

Mixture according to at least one of the preceding claims, which is in the form of pellets.

4. Mixture according to at least one of the preceding claims, whose grain size is present at least 70% by mass in a particle size less than 0.5 mm.

A blend according to any one of the preceding claims, comprising calcium oxide and silica in the following proportions by weight: CaO: 0 to 10 mass%;

Si0 ₂ : 0 to 7 mass%.

6. Mixture according to at least one of the preceding claims, comprising iron oxide in the following proportions by mass:

Iron oxide: 0 to 7 mass%.

7. Method of conditioning a in the iron and

Steel metallurgy on a molten metal melt in a metallurgical vessel containing the following steps:

7. 1 providing a mixture according to at least one of the preceding claims;

7.2 introducing the mixture into the slag located on the molten metal in the metallurgical vessel.

8. Use of a mixture according to at least one of claims 1 to 6 for conditioning a slag present in iron and steel metallurgy on a molten metal in a metallurgical vessel.