JPH0245111B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a lining for protecting the inside of a tundish or foundry ladle for containing molten metal, such as a liquid mesh.

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

[Conventional technology]

Typically, a tundish or casting ladle is
magnesia, alumina or aluminosilicate,
Alternatively, it may have a steel shell with a lining of refractory material, such as refractory cement bricks.

At the end of a casting operation, it is necessary to remove any residue remaining inside the tundish or casting ladle that contained the molten metal. This residue has a strong corrosive effect on the refractory lining, so that the lining wears out over time and has to 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 a permanent refractory lining of tundishes or casting ladles with protection against corrosive wear.

French Patent No. 2,316,327 discloses a tundish or casting machine for the transfer of molten metal by inserting a sinterable element (usually provided in the form of a plate) between a permanent refractory lining and molten metal. It claims to protect the entire inside of the ladle.

French patent No. 2393637 describes a similar protection, which may or may not utilize a prefabricated refractory insulation element that can be sintered in contact with a liquid screen; The permanent refractory lining is bonded to the permanent refractory lining by applying a composition substantially the same as the permanent refractory lining.

In French Patent No. 2451789, a permanent refractory lining of a tundish or foundry ladle is protected by a relatively compressible layer between the permanent refractory lining and an inner lining in contact with the liquid screen; The compressible layer is formed by a base material of organic and/or inorganic fibers coated with a binder.

Another solution claimed in West German Patent Application No. 2010743 is to incorporate non-cohesive sand below and behind the prefabricated elements in order to increase the insulation coefficient of the wear lining in contact with the liquid mesh. Consists of.

The already mentioned French patent No. 2,393,637 discloses that the composition is applied by means of a mold, which leaves a uniform space between it and the wall surface to be lined;
Alternatively, the possibility of insertion is also described, in which case the composition is introduced into the homogeneous space by stuffing and/or blowing, absorption 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, this plate or prefabricated element usually has a
~6 times or more resistance is not provided.

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 cause permanent fire protection. There is a strong possibility that it will reach the lining.

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 reality, this powdered material is produced when molten metal flows through the gap formed between the plates, which are distorted by the action of heat.
There is a strong possibility that this molten metal will be contaminated. Furthermore, by leaking through the gaps, the molten metal 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. Become.

A 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 used in the prefabricated form of the above-mentioned plates and others. without elemental drawbacks.

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:

- Firstly, 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 removed in one piece from the inner wall of the metallurgical vessel by simply 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. 2338100, in order to offer the possibility of limiting the risk of adhesion between the sintered internal lining and the permanent refractory lining,
It has been proposed to place a material with a paper base between the sinterable inner lining and the permanent refractory lining. 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 which a tundish or casting ladle with said internal protective lining and a method for forming the lining are inexpensive and easy to install. It is easily refractory to multiple subsequent casting operations, can withstand high preheating temperatures without damage, and maintains high thermal insulation capacity during multiple subsequent casting operations. This greatly facilitates the cleaning of the vessel at the end of the casting operation by effectively protecting against the risk of adhesion between the internal protective lining and the metallurgical vessel walls.

[Means for solving problems]

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

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 phase 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 is that the cleaning of the inside of the tundish or foundry ladle at the end of the casting operation is a much easier task, and the refractory lining of the vessel is not damaged during the casting process or during cleaning. It's hard to do.

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 tundish or foundry ladle can be considerably extended. This makes it possible to avoid unduly long and frequent casting interruptions, which 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 formed of a single layer with sinterability throughout and of equal thickness to the two-layer protective lining according to the invention. obviously longer than

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
The presence of very fine particles, fluxes, within this lining (fluxes are made up of inorganic particles with a lower melting point than other refractory particles) and the fact that they This is done by keeping the proportion of binder as low as possible in order to locate it in close proximity to the binder.

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 accounting for 3 to 30 wt of the weight of the liquid. % ratio of ethylene glycol alcohol and/or water, the density of the slurry varies depending on the layer within the range of 0.8-3.5Kg/ ^dm3 , and after the application the different The layers are dried. This drying is performed at 100 to 200 for the removal of free moisture.
It is carried out at a temperature within the range of °C. Optionally, with a view to preventing hydrogen contamination of the molten metal, the different layers are preheated to a temperature in the range of 600/1450° C. for removal of composition water and/or crystallization water.

Application of the slurry is preferably carried out by projection and/or spraying, but may also be carried out by any suitable mechanical means such as casting, jetting, vibration, gravity casting, troweling, or the like.

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 attached figure, which is a cross-sectional view of the internal protective lining according to 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 illustrated embodiment, the protective lining comprises three layers 3,
It is made from 4 and 5.

an inner layer 3 which will be in contact with the molten metal as 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:
The particles can be sintered in contact with molten metal to form agglomerates. In other words, the composition and dimensions allow for fusion.

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 to 10 cm.

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 this particle are
The composition and dimensions 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. The layer 4
The thickness of layer 3 is usually comparable to that 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 together by an organic and/or inorganic binder. But other layers 3 and 4
In contrast, layer 5 is not sinterable. Therefore,
When the organic or inorganic adhesive 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:

- mineral binders (for example boron and/or boric acid and/or clay and/or one or more silicates and/or aluminum-containing cements and/or phosphate cements and/or magnesia cements and/or organic Binder and/or synthetic binder (e.g. synthetic adhesive such as phenolic resin) ...0.3-15%, - granular and/or fibrous refractory inorganic particles (e.g. chromium-magnesia and/or magnesia and/or magnesia silicate and/or
or alumina and/or zircon and/or zirconia and/or silica
...70-99.7%, - fibrous and/or granular organic particles and/or carbon-containing material ...0-28.7%, - surfactant compound ...0-5%.

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 the binder. Depends on content percentage.

In order to reliably sinter the layer 3 in contact with the molten metal, it is desirable to employ a composition containing a large amount of refractory inorganic particles. The weight concentration of this particle is 70 ~
The particle size is preferably within the range of 0 to 4 mm. 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 ratio is 75~
It is desirable that it be within the range of 95wt%. The effective size or particle diameter is advantageously between 0 and 3 mm, preferably between 0.25 and 2.5 mm, so that very small particles of less than 0.5 mm in diameter are not present in the composition. First, it limits the sintering process. In this way, even if the layer 3 is completely sintered throughout, the 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 thermal insulation properties, it is still able to cool the molten metal. It can be prevented.

The layer 5 adjacent to the permanent refractory lining 2 is 65~
It is desirable to contain 96 wt% 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 and is separated from the sinterable layer 3 by the heat-insulating intermediate layer 4, it does not sinter under the action of heat and therefore After the binder which initially ensured the cohesion of the layer 5 is destroyed, the layer 5 loses all cohesiveness and becomes powdery. Therefore, after a number of successive casting operations, the internal protective lining of the present invention has become sufficiently worn out that it is necessary to replace it with a new lining, which requires a simple operation. be. 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 and simply. The container can be removed by turning it upside down.

The protective lining according to the invention therefore comprises:
To not only efficiently protect a permanent refractory lining 2 but also to extremely easily clean the inside of a tundish.

In order to carry out the method according to the invention to form a protective lining with the three layers 3, 4, 5 mentioned above, these layers are applied to the walls of the tundish in the form of a slurry containing the solid phase components of each layer. ,
The solid phase component is mixed with a liquid such as water and/or oil in a proportion of 3 to 30% by weight of the liquid. 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 varies between 0.8Kg/dm ³ and 3.5Kg/dm ³ depending on the layers 3, 4 and 5, the density of the inner layer 3 is greater than that of the middle layer 4, and the density of the middle layer 4 is higher than that of the middle layer 4. The density is greater than the density of the layer 5 adjacent to the refractory lining 2.

Layers 3, 4 and 5 applied in this way are 100
Dry at temperatures in the range ~200°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. By drying, free water can 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 layers 3, 4, 5. Therefore, layers 3, 4, and 5 are 600~
Preheated to a temperature within the range of 1450℃.

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 restore the cohesion of the protective lining as a whole. As a result of this agglomeration, the inorganic particles are prevented from falling out of 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 longer service life, since the sintering process practically does not continue beyond the inner layer 3 and thus cannot reach the 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 tundish.

Thirdly, since the layer 5 adjacent to the permanent refractory lining 2 does not sinter and becomes powdery, and since it has no adhesion to the permanent lining, the protective lining at the end of the casting operation is 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 a simplified embodiment of the invention, the layers 4 and 4 are arranged so that there are at least two layers.
and 5 may be omitted.

If the sinterable inner layer 3 is separated from the permanent refractory lining 2 by a non-sinterable layer 5, there is again 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.

The sinterable inner layer 3 forms a permanently refractory lining 2 by means of a layer 4 which is only partially sintered and thus remains friable.
If the layer 4 is separated from the refractory lining 2, only slight adhesion occurs between the layer 4 and the refractory lining 2.

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

Furthermore, if slight contamination of the molten metal by inorganic particles emanating from the protective lining is to be tolerated, the sinterable layer 3 can be replaced by a non-sinterable layer 5 and a partially sinterable layer 4. Layers 3 and 4 can be reversed by being placed between them.

It is also possible with the method according to the invention to apply the extra thickness 7 of the sinterable layer 3 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 the extra thick part 7 is zircon and/or zirconia and/or carbon and/or silicon.
It can contain highly refractory particles of materials such as carbides.

As will be readily understood, it is also possible to partially increase the thickness of the protective lining in other locations of the tundish in the zone that is subjected to the impact of the molten metal poured from the casting ladle located above the tundish. You can also do it.

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

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a tundish or casting ladle which is lined according to the present invention.

Claims (1)

[Scope of Claims] 1. A tundish or casting ladle for containing molten metal, having a metal shell lined with a permanent refractory lining, the permanent lining having a destructible temporary refractory lining. further lined, the temporary lining comprising at least two layers of predetermined composition and particle size, the plurality of layers sequentially depositing a slurry containing refractory inorganic particles, a binder, and a liquid onto the permanent lining. the plurality of layers include an inner layer in contact with the molten metal contained in the tundish or foundry ladle and an outer layer in contact with the permanent lining, the inner layer being in contact with the molten metal contained in the tundish or foundry ladle; The outer layer has a composition and particle size such that it will sinter throughout under the action of the heat of the molten metal contained in the ladle, the outer layer remaining friable even when the inner layer is fully sintered. A tundish or foundry ladle characterized in that it has a different composition and grain size from said inner layer, such that it is unsintered or only partially sintered so as to maintain a 2. The temporary lining comprises the following three layers (a) to (c): (a) an inner layer 3 capable of sintering throughout the layer in contact with molten metal contained in the tundish or casting ladle; (b) an intermediate layer 4 that is covered by the inner layer 3 and maintains its friability by only partially sintering even when the inner layer 3 is sintered over the entire layer; and (c) the above-mentioned Claim 1 characterized in that it consists of an outer layer 5 formed of a non-sinterable material which becomes powder under the action of said heat, covered by an intermediate layer 4 and in contact with said permanent refractory lining. The tundish or casting ladle described in item 1. 3 Said inner layer 3 has the following composition by weight: - Mineral binder (clay and/or silicate and/or aluminum-containing cement and/or phosphate cement and/or magnesia cement and/or organic binder) Agent (synthetic adhesive) ...0.3-15%, - Granular and/or fibrous refractory inorganic particles (chromium magnesia and/or magnesia silicate and/or silica and/or alumina and/or zircon and/or Zirconia)...70 to 99.7%, - Fibrous and/or granular organic particles and/or carbon-containing material...0 to 28.7%, - Surfactant compound...0 to 5%. 4. A tundish or casting ladle according to claim 1. 4. A tundish or casting ladle according to claim 2, wherein the inner layer 3 contains 70 to 99.7 wt% of refractory organic particles having a particle size in the range of 0 to 4 mm. 5. The tundish or casting ladle according to claim 2, wherein the intermediate layer 4 contains 75 to 95 wt% of refractory inorganic particles having a particle size in the range of 0.25 to 2.5 mm. Ladle. 6. The tundish or casting ladle according to claim 2, wherein the outer layer 5 contains 65 to 96 wt% of refractory inorganic particles having a particle size in the range of 0 to 5 mm. 7. , a tundish or casting ladle according to claim 1, wherein an extra thickness 7 is provided in the zone of floating slag 6 above the molten metal.8. A method of forming a temporary protective lining, wherein the tundish or casting ladle has a metal shell lined with a permanent refractory lining, the permanent lining being further lined with a destructible temporary refractory lining. and the temporary lining is comprised of at least two layers of predetermined composition and particle size, which layers are sequentially applied onto the permanent lining with a slurry containing refractory inorganic particles, a binder, and a liquid. It is formed by
The plurality of layers includes an inner layer in contact with molten metal contained in a tundish or casting ladle, and an outer layer in contact with the permanent lining, the inner layer comprising:
having a composition and particle size such that it will sinter throughout under the action of the heat of molten metal contained in a tundish or casting ladle, the outer layer comprising:
for tundishing or casting, such that the inner layer has a different composition and particle size than the inner layer, such that the inner layer remains friable when fully sintered, or is only partially sintered. In the method of forming a temporary lining in a ladle, a plurality of different layers 5, 4, 3 are prepared with a density of 0.8-3.6 Kg/3, with the solid components of these layers being mixed with the liquid in a proportion of 3-30% of the weight of the liquid. dm ³ as a slurry, and the above applied different layers 5, 4, 3.
and drying at a temperature in the range of 100 to 200°C. 9 After the drying, the plurality of layers 5, 4, 3 are
9. A method according to claim 8, characterized in that it is preheated to a temperature in the range of 600 to 1450<0>C. 10. The method according to claim 8, characterized in that the application is carried out by spraying.