JPS63247589A - Lining for protecting inside of metallurgical vessel and lining forming method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lining for protecting the inside of a metallurgical vessel for containing molten metal, such as liquid steel.

The invention also relates to a method of forming an internal protective lining of the above type.

Metallurgical vessels which may be desired to be protected by an internal lining according to the invention include casting ladles, tundishes,
Alternatively, there is a slag container, etc.

[Conventional technology]

Typically, metallurgical vessels of the above type have a steel shell with a lining of refractory material, such as magnesia, alumina or aluminosilicate, or refractory cement bricks.

At the end of a casting operation, it is necessary to remove any residue remaining inside the container that contained the molten metal. This residue has a strong corrosive effect on the refractory lining, which results in wear and tear over time.
Must be replaced after a limited period of use. However, this replacement work is complicated and expensive.

A number of solutions have already been proposed to provide permanent refractory linings of metallurgical vessels with protection against corrosion wear and tear.

French Patent No. 2,316,027 discloses a container for the transfer of molten metal or It claims to protect the entire inside of the ladle.

French Patent No. 2,393.637 describes a similar protection, which may or may not utilize prefabricated refractory insulation elements that can be sintered in contact with liquid steel. The element is bonded to a permanent refractory lining by applying a composition substantially identical to the element.

In French Patent No. 2,451,789, a permanently refractory lining of a metallurgical vessel is protected by a relatively compressible layer between the permanently refractory lining and an inner lining in contact with the liquid steel, the compressible The flexible layer is formed by a base of organic and/or inorganic fibers coated with a binder.

Another solution, claimed in West German patent application no. Consists of incorporating sexual sand.

The already mentioned French patent No. 2.393.637 also describes the possibility of applying, projecting or inserting said composition by means of a mold which leaves a uniform space between it and the wall surface to be lined. In this case, the composition is introduced into the homogeneous space by stuffing and/or blowing, suction or vibration.

All these solutions are associated with a number of drawbacks.

Internal protective linings consisting of plates or prefabricated elements are relatively expensive and complex to install. Furthermore,
Typically, the plate or prefabricated element will not resist more than 5 or 6 subsequent casting operations.

In order to avoid hydrogen contamination of the molten metal, it may be necessary to preheat the lining plate to a temperature of 600° C. or higher to remove moisture and organic compounds contained in the lining plate.

Plates or prefabricated elements tend to warp under the action of heat during preheating, thereby forming gaps between the joints of the plates or elements, with the result that molten metal can leak through these gaps and damage the permanent refractory lining. There is a strong possibility that it will reach .

This condition is even worse if the gap formed between the plate and the permanent refractory lining is filled with powdered material such as sand. In fact, this powdered material is likely to contaminate the molten metal as it flows through the gaps formed between the plates that have been distorted by the action of heat. Furthermore, the molten metal leaks through the gaps and mixes with the powdered material to form a lump that adheres strongly to the permanent refractory lining, making cleaning of this permanent lining very difficult.

The single-layer internal lining produced by projection or spray coating as described in French Patent No. 2,393.637 is obtained from a mixture of refractory inorganic particles and an inorganic or organic binder and is Without the disadvantages of prefabricated elements.

This type of internal lining must necessarily sinter in contact with the molten metal so that inorganic particles do not break away from this internal lining and contaminate the molten metal.

Since the above-mentioned sintering process occurs gradually and after a period of contact between the molten metal and the internal protective lining the entire lining is sintered, it results in two disadvantages:

First of all, when the entire internal protective lining is sintered, the thermal insulation capacity of this lining is considerably reduced, so that there is a potential risk of cooling of the molten metal.

Secondly, when the entire internal lining is sintered, the entire sintered lining adheres to the permanent refractory lining, making cleaning of the latter very difficult.

For the above two reasons, the internal protective lining must not be completely sintered. Then, at the end of the casting operation,
The inner lining can be detached in one piece from the inner wall of the metallurgical vessel simply by overturning the metallurgical vessel.

The protective lining can therefore only be used for a few casting operations and must therefore be replaced frequently. Replacement is also undesirable from an economic point of view since it is relatively expensive and causes interruptions in the casting operation.

In French patent no. 2.338.100, a combination of a sintered internal lining and a permanent refractory lining is proposed in order to provide the possibility of limiting the risk of adhesion between the sintered internal lining and the permanent refractory lining. It has been proposed to arrange a material with a paper substrate in between. However, this material quickly carbonizes under the action of heat and eventually cannot actually perform the above function.

[Problem that the invention seeks to solve]

The present invention aims to overcome the drawbacks of the above-mentioned known solutions and provides an internal protective lining for this purpose, which is inexpensive, easy to install and can be used in a number of subsequent casting operations. It is fire resistant and allows to withstand high preheating temperatures without damage and maintain a high thermal insulation capacity during multiple subsequent casting operations, ensuring that the internal protective lining and the metallurgical vessel wall are The cleaning of the container at the end of the casting operation is greatly facilitated by effective protection against the risk of fouling.

[Means for solving problems]

In the present invention, an internal lining having the function of protecting the interior of a metallurgical vessel for containing molten metal is formed of a material having a base of refractory inorganic particles coated with a binder. The lining comprises at least two layers: - a layer having refractory inorganic particles of composition and particle size such that they sinter throughout the layer under the action of the heat of the molten metal contained in the metallurgical vessel; , and a refractory composition and particle size such that even when the second layer is fully sintered, the second layer does not sinter or only partially sinters to maintain friability. a second layer comprising inorganic particles.

The internal protective lining according to the invention is thus composed of at least two different layers. The first of these two layers gradually sinters in contact with the molten metal. After prolonged contact, for example after a subsequent casting operation, the first layer is sintered throughout.

The second layer is either unsintered or only partially sintered so that it remains friable even when the first layer is fully sintered. Therefore, when the second layer is in contact with the permanent refractory lining, the second layer does not adhere to the refractory lining. As a result, even when the first layer is completely sintered, the risk of adhesion between the internal protective lining and the refractory lining is avoided. The result achieved thereby is that the cleaning of the inside of the metallurgical vessel at the end of the casting operation is a very easy task, and the refractory lining of the vessel is less likely to be damaged during the casting process or during cleaning.

It is also known that sintering of the refractory lining has a negative effect on its own thermal insulation properties. Since the second layer is not sintered or is only partially sintered, the second layer is sufficiently Continue to ensure a certain degree of insulation.

By combining two layers, one sinterable and the other partially sinterable or non-sinterable, the service life of the refractory lining of a metallurgical vessel can be considerably extended and therefore unduly extended. It is possible to avoid casting interruptions, which are frequent and result in large cost penalties.

It is therefore surprising that the service life of the two-layer protective lining according to the invention is longer than that of a protective lining made of a single layer with sinterability throughout and of equal thickness to the two-layer protective lining according to the invention. Obviously long.

Sintering is a physicochemical phenomenon that creates a bond between two inorganic particles. The sintering process takes place at a temperature clearly below the melting point of these particles. This process is accelerated by the high pressure exerted by the molten metal on the protective lining according to the invention and by the presence within this lining of very fine particles, flux (the flux is mixed with other refractory particles). (inorganic particles having a melting point lower than that of the inorganic particles) and by keeping the proportion of binder as low as possible in order to locate the inorganic particles very close to each other.

Furthermore, in the method of forming an internal protective lining according to the invention, the different layers are applied successively using a slurry containing the solid phase component of the layer to be formed, the solid phase component comprising 3 to 30 wt of the weight of the liquid. % ratio of ethylene glycol alcohol and/or water, the density of the slurry is 0.8-3.5 kg/
It varies from layer to layer within the range of dm3, and after the application the layer is dried. This drying is carried out at a temperature in the range of 100-200 DEG C. to remove free moisture. In some cases, with a view to preventing hydrogen contamination of the molten metal, political parties may be required to use six
Preheated to a temperature in the range 00/1450°C.

Preferably, the slurry is applied by projection and/or spraying;
This can also be done by suitable mechanical means such as troweling.

The method according to the invention is extremely economical and is perfectly suitable for applying layers with different compositions in succession.

〔Example〕

Other features of the invention will become more apparent to those skilled in the art upon consideration of the following description.

Reference is made to the accompanying figure, which is a cross-sectional view of the internal protective lining of the invention. In the embodiment described here, the protective lining consists of three superimposed layers and is applied to and placed inside an intermediate casting vessel known as a tundish.

In the embodiment shown, the tundish for accommodating liquid steel has a steel shell 1 whose inner surface is provided with a permanently refractory lining made of refractory bricks 2. ing.

An internal protective lining is applied in a slurry over the permanent refractory lining. In the embodiment shown, the protective lining is made up of three layers 3,4.5.

The inner layer 3, which comes into contact with the molten metal when it is being poured into the tundish, is formed by a mixture of refractory inorganic particles bound by an organic and/or inorganic binder.

The composition and effective dimensions of this refractory inorganic particle are determined by the particle force q
It is of a composition and dimensions that allows it to sinter, or in other words, fuse, to form an agglomerate in contact with the capacitive metal.

The caking that occurs in contact with molten metal proceeds very gradually and usually eventually reaches the entire thickness of layer 3, i.e. within the contact period during which sintering is completed throughout the layer. The final process takes place within a few hours or after several casting runs.

It is very obvious that the greater the thickness of the layer 3, the longer the time required for the sintering of the layer to be completed over its entirety. The thickness of the layer 3 is usually in the range 1-1Qcn+.

The intermediate layer 4 is also formed by a mixture of inorganic particles bound together by an organic and/or inorganic binder. The composition and effective dimensions of the particles are such that the particles are only partially sintered so that the layer 4 remains friable even after the inner layer 3 has sintered throughout its entirety. be. The thickness of layer 4 is typically comparable to the thickness of layer 3.

Layer 5 is in direct contact with the refractory brick 2 lining. The layer 5 is also formed by a mixture of refractory inorganic particles bound by an organic and/or inorganic binder.

However, unlike the other layers 3 and 4, layer 5 is not sinterable. Therefore, when the organic or inorganic binder that initially made the layer sticky is destroyed by the action of heat, the layer 5 becomes powdery and no longer adheres to the lining of the refractory brick 2.

Layers 3 and 4 are sinterable and partially sinterable, respectively, and have the following desirable weight compositions:

monomineral binders (e.g. boron and/or boric acid and/or clay and/or one or more silicates and/or aluminum-containing cements and/or
or phosphate cement and/or magnesia cement and/or organic binder and/or synthetic binder (e.g. synthetic adhesive such as phenolic resin >-
−−・−・−−−−−1−−−−−−・・−−−−
- 0.3 to 15%, - granular and/or fibrous refractory inorganic particles (e.g. chromium magnesia and/or magnesia and/or magnesia silicate and/or alumina and/or zircon and/or zirconia and/or silica----------------------
・−−−−−1−−−・−−−−−−−−−−70～
99.7%, - fibrous and/or granular organic particles and/or carbon-containing materials -------・-・--・-・
- 0 to 28.7%, - Surfactant compound - - - - - - 0 to 5%.

The strength of the sinterability of layers 3 and 4 depends on the characteristics of the composition of the refractory inorganic particles, the effective size of the particles, the presence or absence of iron oxides or carbonates of alkali metals or alkaline earth metals, and the use of binders. Depends on content percentage.

In order to ensure complete sintering of layer 3 upon contact with molten metal, it is desirable to employ a composition containing a large amount of refractory inorganic particles. The weight of this particleffl? Et degree is 70~
The particle size is preferably within the range of 0 to 4 fins. This necessarily results in the presence of a considerable number of particles of very small size, which has a favorable effect on the sintering process.

The intermediate layer 4 contains refractory inorganic particles in a smaller proportion than the fully sinterable layer 3. This proportion is desirably within the range of 75 to 95 wt%. The effective size or particle diameter is advantageously between 0 and 3, and between 0.25 and 2.
．． 5 mm, so that the diameter is 0.5 mm.
Very small particles below 5 n are not present in this composition, which limits the sintering process. In this way, even if layer 3 is completely sintered throughout, layer 4 is only partially sintered and thus remains friable or brittle.

Since the intermediate layer 4 is only partially sintered, it maintains its thermal insulation properties, so that even if the inner layer 3 is completely sintered and loses its initial thermal insulation properties, the molten metal remains intact. Cooling can be prevented.

The layer 5 adjacent to the permanent refractory lining 2 is 65-96w
It is desirable to contain t% of refractory inorganic particles, and the diameter of the particles is preferably in the range of 0 to 5 mm. Since the outer layer 5 has a low concentration of refractory inorganic particles,
Since it is separated from the sinterable layer 3 by a heat insulating intermediate layer 4, it does not sinter under the action of heat and therefore initially the layer 5
After the binder which ensured the cohesion of the layer 5 is destroyed, the layer 5 loses its cohesiveness and becomes powdery. Therefore, after a number of successive casting operations, the internal protective lining of the invention has become sufficiently worn out that it can be replaced with a new lining, the operations required for this purpose being simple. That is, since the layer 5 adjacent to the permanent refractory lining 2 is in powder form, there is no adhesion between the permanent lining and the protective lining, so that the protective lining can be removed as one piece from the permanent lining very easily.
It can be removed by simply flipping the tandish upside down.

Therefore, the protective lining according to the invention not only efficiently protects the permanent refractory lining 2, but also makes it possible to clean the interior of the tundish very easily.

By carrying out the method according to the invention, the three layers described above are
These layers are applied to the walls of the tundish in the form of a slurry containing the solid phase components of each layer, which solid phase components are mixed with a liquid such as water and/or oil and a liquid are mixed at a ratio of 3 to 30% by weight. Alcohols are also suitable (eg ethylene glycol).

The slurry must have sufficient viscosity to be a paste that does not flow when applied.

The density of the applied slurry is 0.5 by layers 3 and 4.5.
8 kg/di' ~3.5 kg/da+3
the density of the inner layer 3 is greater than the density of the intermediate layer 4, and the density of the intermediate layer 4 is greater than the density of the layer 5 adjacent to the refractory lining 2.
greater than the density of

53,4.5 applied in this way is 100-20
Drying is carried out at a temperature within the range of 0°C. The drying means are, for example, flame drying and/or hot air blowing, or an electric resistance heater located within the tundish and mounted on a cover that closes the tundish. Drying allows free moisture to be removed from the slurry forming the different layers.

In order to possibly protect against the risk of hydrogen contamination of the molten metal, it is useful to remove all organic components and the total amount of water of composition and water of crystallization from layer 3.4.5. For this purpose, 113.4.5 is preheated to a temperature in the range 600-1450°C.

At this high temperature, the inorganic and/or organic binder used for the initial agglomeration of layers 3, 4.5 decomposes. This heating to high temperatures has the effect of partially sintering the inner layer 3. This partial sintering process can open up the agglomeration of the protective lining as a whole. As a result of this agglomeration, the inorganic particles are prevented from falling out from the protective lining and the molten metal is not contaminated when it is poured into the tundish).

Compared to conventional coated linings of the sinterable monolayer type, which have a similar composition to the inner layer 3 of the protective lining according to the invention, the lining according to the invention exhibits unexpected technical advantages with respect to the same total thickness.

First of all, the protective lining according to the invention has a distinctly long service life, since the sintering process practically does not continue beyond the inner layer 3 and therefore cannot reach a permanent refractory lining, 2.

Secondly, since the intermediate layer 4 is only partially sintered and the layer 5 adjacent to the permanent refractory lining 2 is not sintered at all, these layers 4 and 5 ensure good thermal insulation properties. , thereby preventing cooling of the molten metal within the tandi nosh.

Thirdly, the protection at the end of the casting operation, since the layer 5 adjacent to the permanent refractory lining 2 does not sinter and becomes powdered, and also because it has no adhesion to the permanent lining. The lining can be removed extremely easily.

There is therefore no risk of damaging the permanent refractory lining by using tools such as pneumatic drills in an attempt to remove clots adhering to the refractory lining.

It is clear that the invention is not limited to the embodiments of construction described above. Accordingly, many modifications are possible without departing from the scope or spirit of the invention.

Therefore, in hour wheel embodiments of the invention, one of layers 4 and 5 may be omitted so that there are at least two layers.

If the sinterable inner layer 3 is separated from the permanent refractory lining 2 by a non-sinterable layer 5, there is also no risk of adhesion occurring between said layer 5 and the permanent refractory lining 2. However, the thermal insulation capacity of these two layers is clearly lower than in the case of a protective lining with three layers.

If the sinterable inner layer 3 is separated from the permanent refractory lining 2 by a layer 4 which is only partially sintered and remains friable, adhesion may occur between said layer 4 and the refractory lining 2. Even if it is, it is a minor adhesion.

Furthermore, if the protective lining is made of three layers,
It is possible to arrange a non-sinterable layer 5 between the sinterable layer 3 and the partially sinterable layer 4.

Furthermore, if it is to be tolerated that the molten metal is slightly contaminated by inorganic particles emanating from the protective lining, the sinterable layer 3 can be combined with the non-sinterable layer 5 and the partially sinterable layer 4. Layers 3 and 4 can be reversed by being placed in between.

Further, by the method according to the present invention, the extra thickness part 7 of the sinterable layer 3
It is also possible to apply it opposite the zone of floating slag 6 floating on the surface of the molten metal.

This extra thickness 7 can have the same composition as layer 3 in order to be sintered at the same time as layer 3. The extra thickness 7 improves the protection provided by the internal lining according to the invention in the slag zone, which is the most susceptible zone of the tundish.

The extra thickness 7 can also have a composition different from that of the layer 3 in order to provide stronger protection against slag. Therefore, the composition of the layer forming this extra thick part 7 is zircon and/or zirconia and/or carbon and/or
Alternatively, it can contain highly refractory particles of materials such as silicon carbide.

As will be readily understood, at other locations on the tundish, the thickness of the protective lining is partially increased in the zones that are impacted by the molten metal flow injected from the casting ladle located above the tundish. You can also do that.

Practical experience has shown that it is also possible to apply the different layers by troweling or shaping.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a metallurgical vessel lined according to the present invention. May 1, 1986 Director General of the Patent Office Mr. Kunio Ogawa ■, Indication of the case 1984 Patent Application No. 284081 2, Name of the invention Protecting the inside of a metallurgical container Lining and lining formation method 3, relationship with the case of the person making the amendment Patent applicant's name F. Dosan et Compagne 4, Agent's address: Shizuko Toranomon Building, 8-10 Toranomon-chome, Minato-ku, Tokyo 105 Telephone: 504- 07215, date of amendment order 6, specification to be amended 7, engraving of the statement of contents of the amendment (no change in content) 8, engraving of the list of attached documents 1 copy

Claims (1)

[Claims] 1. An internal lining for protecting the interior of a metallurgical vessel for containing molten metal, formed of a material having a base of refractory inorganic particles coated with a binder. in a lining containing at least two layers of: - refractory inorganic particles of a composition and particle size such that they sinter throughout the layers under the action of the heat of the molten metal contained in the metallurgical vessel; a layer (3) comprising a layer (3), and - such that when the first layer (3) is completely sintered, the second layer is not sintered or is only partially sintered in order to maintain its friability. a second layer (4 or 5) having refractory inorganic particles of composition and particle size; 2. In an internal protective lining for a metallurgical vessel with a permanent lining (2) of refractory material, at least two layers: - an inner layer (3) for direct contact with said molten metal; an inner layer (3) capable of sintering over the inner layer (3) in contact with the molten metal; and - a layer (4 or 5) covered by the inner layer (3), in contact with the molten metal. a layer (4 or 5) formed of a non-sinterable material that becomes powdery or remains friable even when the inner layer (3) is sintered throughout; The lining according to claim 1. 3. In the internal protective lining, the following three layers: - an inner layer (3) for direct contact with said molten metal, sintering over said inner layer (3) in contact with said molten metal; - a layer (4) covered by the inner layer (3), which is in contact with the molten metal and which also partially sinters when the inner layer (3) in contact with the molten metal is sintered throughout; - a layer (4) formed of a material that is only sintered and remains friable; and - a layer (5) in direct contact with the refractory permanent lining, which forms a powder under the action of heat. Lining according to claim 1, constituted by a layer (5) formed of a non-sinterable material. 4. In the internal protective lining, the following three layers: - an inner layer for direct contact with said molten metal and capable of sintering over said inner layer in contact with said molten metal; - a layer covered by an inner layer, formed of a non-sintering material which becomes powder under the action of heat, and - a layer in direct contact with the refractory permanent lining, which does not sinter 2. The lining according to claim 1, further comprising: a layer that can be sintered only partially and maintain its friability even when the entire sintered layer is sintered. 5. In the internal protective lining, the sinterable layer (3
) and partially sinterable layer (4) has the following composition by weight: - mineral binder (clay and/or silicate and/or aluminium-containing cement and/or phosphate cement and/or magnesia cement and/
Or organic binder (synthetic adhesive)...0.3-15%
, - granular and/or fibrous refractory inorganic particles (chromium magnesia and/or magnesia silicate and/or
or silica and/or alumina and/or zircon and/or zirconia)...70-99.
7%, - fibrous and/or granular organic particles and/or carbon-containing material...0 to 28.7%, - surfactant compound...0 to 5%. Lining as described in section. 6. In the inner protective lining, the sinterable layer (3) for contacting the molten metal preferably has a thickness of 0 to 4 m.
refractory organic particles having a particle size in the range of 70 to
The lining according to claim 2, containing 99.7 wt%. 7. In the internal protective lining, said layer (4) which is partially sinterable but remains friable, preferably 0.25
Lining according to claim 2, containing from 75 to 95 wt% of refractory inorganic particles having a particle size in the range of -2.5 mm. 8. In the internal protective lining, said powdered non-sinterable layer (5) contains 65 to 96 wt% of refractory inorganic particles with a desired particle size in the range of 0 to 5 mm. The lining described in item 3. 9. In the internal protective lining, an extra thickness (7) of the layer for complete sintering in contact with the molten metal is formed opposite a zone of floating slag (6) above the molten metal. The lining described in range 1. 10. In the internal protective lining, an extra thickness (7) is provided opposite the zone of floating slag (6) on the molten metal, the extra thickness being in contact with the molten metal to completely sinter it; Claims 1. Formed by a layer applied to said layer (3) on the inside of said layer (3), said extra-thickness layer being formed of a material containing inorganic particles imparting resistance to the attacking action of slag. The lining described in item 1. 11. A method of forming an internal lining to protect the interior of a metallurgical vessel for containing molten metal, the method comprising:
formed of a material having a base of refractory inorganic particles coated with a binder, at least two layers: - over the entire layer under the action of the heat of the molten metal contained in the metallurgical vessel; a layer (3) having refractory inorganic particles of a composition and particle size such that the first layer (3) sinters completely; a second layer (4 or 5) having refractory inorganic particles of a composition and particle size such that they are not sintered or only partially sintered in order to (5, 4, 3) is subsequently applied in the form of a slurry containing the solid phase component of the layer to be formed, the solid phase component being mixed with the liquid in a proportion of 3 to 30 wt% of the weight of the liquid. The density of the slurry is 0.8 to 3.5 kg.
/dm^3, and after the application the different layers (5, 4, 3) differ from 100 to 20
A method for forming a lining, which is dried at a temperature in the range of 0°C. 12. The method of forming a lining according to claim 11, wherein the different layers (5, 4, 3) are preheated to a temperature in the range of 600 to 1450° C. for removal of composition water and/or crystallization water. .