Method for patching and lining-making of steel ladle

Abstract

The invention relates to a steel ladle patching and lining making method which comprises the following steps: when a steel ladle is transferred to a safety line, cleaning residual steel slag on the surface of the steel ladle after the steel ladle is off line, then smearing high-strength bonding plastic refractory, and enabling the surface of the steel ladle smeared with the high-strength bonding plastic refractory to be smooth; then, the short bricks are laid layer by layer from bottom to top and tightly squeezed; after construction is completed, the steel ladle is conventionally baked and put into use; and after each off-line process, repeated patching and lining making are carried out, and the maintenance is carried out circularly in this way. The built steel ladle, the residual lining and the short bricks are bonded into a whole, the steel ladle cannot be peeled off and broken in the conventional baking and using process, the unit consumption of a refractory material is remarkably reduced, and the method plays an important role in reducing cost, improving efficiency and reducing energy consumption.

Description

Technical Field

[0001] The invention belongs to thermal kiln construction and maintenance technology, and in particular relates to a ladle masonry and repair method. Background Art

[0002] At present, there are two main methods of ladle use technology. One is castable ladle lining. For a new ladle shell, a permanent layer is first constructed, and then the inner mold is installed and cast with refractory castables. Then it is cured and baked, and put into operation. After going offline, the surface slag steel is cleaned, and the mold is installed for sleeve pouring construction. Then it is cured, baked and used. This infinite cycle leads to very little refractory waste and very low refractory unit consumption, even reaching less than 1kg / t. The second method is brick-built ladle. After the permanent layer is built, different refractory bricks are laid in different parts according to different requirements. After the masonry is completed, it is baked and put into use. When the slag line and other local losses are serious, the slag line is replaced offline and the local serious parts are excavated and repaired. Then it is baked and put online for use. Under normal circumstances, when the slag line erodes to the safety line again, it is offline, and all working layers are stripped off and replaced with new working layers. This construction and maintenance method has reached a level of about 3kg / t for the refractory unit consumption of 100t refined ladle. In fact, the amount of discarded refractory materials removed is more than 1.5kg / t, which is more than 50%, which is a huge waste of resources. Wasting refractory resources means high energy consumption and high costs.

[0003] Ruitai Magang New Material Technology Co., Ltd. uses high-grade corundum spinel coating material on 300 t ladle, with an adhesion rate of 95%. It can be used 30 to 35 times after one coating. It has achieved good results. Using coating material to coat the lining is a way to balance erosion and increase service life. However, its erosion resistance is insufficient. When the coating layer is thin, it will peel off, resulting in uneven ladle conditions, which makes it difficult to judge the ladle. It also does not fundamentally solve the problem of excessive amount of waste refractory materials removed during medium and major repairs.

[0004] Patent 201810610506.2 is "a composite refractory and wear-resistant plastic", which uses conventional aluminum-silicon refractory raw materials, which is not suitable for refining ladle lining. Its corrosion resistance is insufficient. Instead, conventional silicate binders are used. Silicates generate liquid phase at very low temperatures. This is extremely unfavorable for high temperature resistance and corrosion resistance. Patent 202010538345.8 is "a kind of aluminum silicate refractory plastic", which is also an aluminum-silicon material and uses clay as a binder. It is difficult to form a bond with the original layer, which will cause peeling or high-temperature shedding. Patent 201511011055.3 is "high-aluminum refractory plastic", which uses conventional phosphate binders. Although this binder has good viscosity, it is not resistant to high temperatures and cannot meet the high-temperature adhesion and service life requirements of the ladle. Patent 201310425093.8 is "hot-repair refractory plastic", which is also a high-aluminum plastic and uses high-aluminum cement. This introduces CaO, and although the strength increases, the viscosity and corrosion resistance deteriorate. If used on a ladle, the risk of peeling increases and the service life is reduced. Patent 202010127849.0 is "Micropowder-bonded coating for ladle lining and its preparation method and application", which is an aluminum-magnesium spinel coating. Micropowder bonding is adopted. One advantage of micropowder bonding is that it is sintered at high temperature to form a good high-temperature bond. However, as there is a lack of bonding between the residual lining and the new lining, the lack of bonding will lead to peeling and cracking, resulting in a low service life and failing to achieve the desired service life. Patent 202011337689.9 is an aluminum-magnesium repair material for a ladle, which is a castable-type repair. The residual lining and the repair material layer are not firmly bonded at high temperature. Temperature fluctuations at high temperatures will cause peeling, especially when the residual thickness of the patching bricks is relatively thin, it is easier to peel off, which leads to difficulties in judging the ladle and increased consumption.

[0005] In summary, the current methods for ladle repair include 1) lining by coating, 2) lining by gunning, and 3) lining by casting, which can increase the service life of the ladle. This leads to a reduction in the unit consumption of refractory materials for the ladle. The materials used are coating materials, gunning materials, and castables. No matter which material, the performance is not as good as that of bricks. The durability is inferior to that of bricks. Although there are patents for patching with bricks, the bonding problem is not solved. Through the above-mentioned coating, gunning, and casting, the junction between the residual lining and the lining is prone to cracking and peeling. This leads to insufficient safety in use and high unit consumption of refractory materials, which needs further improvement and improvement. Summary of the invention

[0006] The object of the present invention is to provide a method for patching and lining a ladle, so as to solve the problems of insufficient direct bonding between the residual lining and new bricks and insufficient material durability.

[0007] The specific technical scheme of the present invention is as follows:

[0008] A method for patching and lining a ladle, comprising the following steps:

[0009] When the ladle is running to the safety line, the residual steel slag on the surface of the ladle is cleaned after it comes off the line, and then high-strength bonding plastic is applied to make the surface coated with high-strength bonding plastic smooth; then short bricks are laid layer by layer from bottom to top and squeezed tightly; after the construction is completed, the ladle is routinely baked and put into use; every time it comes off the line, it is repeatedly patched and lined, and the maintenance cycle is repeated.

[0010] The preferred solution is that the high-strength bonding plastic material is composed of the following components in parts by mass: 20-60% granular material and 20-45% fine powder. The material of the granular material and the fine powder is the same as the material of the position to be repaired, and the rest is additives, which are composed of three parts: plasticizer, reinforcing agent and recarburizer, plus 8-30% carbon binder.

[0011] A preferred solution is that the fine powder has a particle size of ≤0.15 mm, of which particles ≤10 μm account for no less than 5%.

[0012] A preferred embodiment is that the reinforcing agent is one of silicon powder, aluminum powder, chromium powder, titanium powder or nickel powder, the plasticizer is one of trioctyl phosphate, dioctyl phthalate or soft clay, the recarburizer is one of colloidal sulfur, paraformaldehyde or urotropine, and the carbon binder is phenolic resin, furan resin, asphalt binder or a combination thereof.

[0013] The preferred solution is that the method for smoothing the surface by applying high-strength adhesive plastic is as follows: taking the thickest part of the residual bricks in the ladle as the reference, the thickness of the high-strength adhesive plastic layer applied there is 0.5-2 mm; the coating thickness is determined according to the recessed size of other parts to ensure a smooth and flat overall surface.

[0014] The present invention has the following beneficial effects:

[0015] 1. This application selects different high-strength bonding plastic materials according to the different materials of different parts of different ladles to control the different corrosion resistance and thermal expansion, and ensure the basic consistency of the line changes of the residual lining, the new patch bricks and the high-strength bonding plastic. This ensures that when the temperature changes during use, the stress generated between the interfaces is very small, and there will be no cracking and peeling. And because the material is basically the same as the bricks in the same position, coupled with the use of additives and carbon binders, the corrosion resistance will be greatly improved. Therefore, in terms of adhesion, peeling resistance and corrosion resistance, the new high-strength bonding plastic has the same corrosion resistance as the bonded residual lining and new bricks.

[0016] 2. The high-strength adhesive plastic material used in this application for patching and lining high-temperature kilns is used when the kiln is used to a safe thickness limit. Instead of dismantling the kiln, the kiln is patched and lining is continued, that is, the adhesive plastic material is applied to the surface of the remaining lining, and the patching short bricks are laid inside and squeezed tightly, so that the high-strength adhesive plastic material is squeezed into the gap between the remaining lining and the short bricks. In this way, the high-strength adhesive plastic material firmly bonds the remaining lining and the patching short bricks together, and the kiln is used like a new lining. Such unlimited recycling makes the waste refractory materials approach zero, significantly reducing the unit consumption and cost of refractory materials. DETAILED DESCRIPTION

[0017] In order to demonstrate the essential features and significant improvements of the present invention, the following examples are used to further illustrate the implementation methods and effects.

[0018] Embodiment 1:

[0019] For a 150t refining ladle, which uses magnesia carbon bricks as the ladle lining, after 50 uses, the thinnest residual thickness of the eroded slag line is only 60mm, and it needs to be replaced offline. If conventional means are used for replacement, 10t of bricks are needed for each replacement of the slag line, and the ladle needs to be taken offline for overhaul after about 50 operations. In this way, the unit consumption of refractory materials reaches 3.5kg / t.

[0020] The method of patching and lining the ladle of the present invention is adopted. When the number of uses reaches 50 times, the ladle is cooled after being offline, the slag steel on the surface of the residual lining is cleaned, and then a layer of high-strength bonding plastic is applied. Then, according to the defects of different parts, slag line magnesia carbon bricks of different thicknesses are patched, and squeezed and compacted. In this way, only 4 tons of bricks are used for each repair, saving 6 tons of magnesia carbon bricks, and then it can continue to be used for 50 times, and the unit consumption of refractory materials is reduced by 0.5 kg / t.

[0021] Embodiment 2:

[0022] For a 120t common refining ladle, aluminum-magnesia-carbon bricks are used in the molten pool and magnesium-carbon bricks are used in the slag line. After 65-70 times of use, the slag line is replaced and then replaced after another 60-70 times. The unit consumption of refractory materials is about 2.6kg / t.

[0023] The method for patching and lining the ladle of the present invention is adopted, that is, after the slag line is used for 65 to 70 times, the sticky slag and residual steel at the slag line are cleaned, and then high-strength plastic is applied, and then slag line patching bricks of different thicknesses are patched according to the defects of different parts, and the bricks are squeezed and compacted, and then the ladle is put back online for another 60 to 70 times before being taken offline. After cleaning the slag steel of the entire ladle lining, high-strength plastic is first applied, and the molten pool is patched with aluminum-magnesium-carbon bricks, and the slag line is still patched with magnesium-carbon bricks. During the masonry process, each brick is squeezed and compacted, and the thickness of the patching bricks is strictly controlled to ensure the regularity and volume of the ladle lining. After online baking and being put into circulation, the unit consumption of refractory materials is reduced to 1.5kg / t, and the unit consumption of refractory materials is reduced by 1.1kg / t.

[0024] Embodiment 3:

[0025] For the 60t special steel refining ladle, both the molten pool and the slag line are made of magnesia carbon bricks. After 50 uses, the slag line is replaced and then replaced after 45 uses. The refractory material consumption is about 4.2kg / t.

[0026] The method for patching and lining a ladle of the present invention is adopted, that is, after the slag line is used 50 times, the sticky slag and residual steel at the slag line are cleaned, and then high-strength bonding plastic is applied, and then slag line magnesium carbon bricks of different thicknesses are patched according to the defects of different parts, and squeezed and compacted. In this way, it is put online and used for 45 times before being offline. After cleaning the slag steel of the entire ladle lining, first apply high-strength bonding plastic, and use magnesium carbon bricks to patch the lining from the molten pool to the top. During the masonry process, squeeze and compact each brick, strictly control the thickness of the patching bricks, and ensure the regularity and volume of the ladle lining. After online baking and being put into circulation, the unit consumption of refractory materials is reduced to 2.2kg / t, and the unit consumption of refractory materials is reduced by 2kg / t.

[0027] The high-strength bonding plastic in the above-mentioned embodiments 1-3 is prepared according to the following formula:

[0028]

[0029] The high-strength bonding plastic is used to bond magnesia carbon bricks and aluminum-magnesia carbon bricks. Taking Example 1 as an example, when used to bond MT-14A magnesia carbon bricks, its granular material and fine powder are mainly composed of fused magnesia sand and -195 graphite, aluminum powder, magnesium aluminum powder, short carbon fiber as reinforcing agent, dioctyl phthalate as plasticizer, colloidal sulfur as carburizer, after curing at 200°C, hot strength test is carried out under the conditions of 1400°C and 3h carbon burial, and its flexural strength can reach 5.5MPa. Some magnesia carbon bricks break at the body, not at the bonding point, so it can be confirmed that the plastic bonding is very strong.

[0030] At the same time, by comparing Example 2-2 with Comparative Example 2, when used to adhere aluminum-magnesium-carbon bricks, the bonding properties are also improved by adding plasticizers and recarburizers.

[0031] The above are only preferred embodiments of the present invention. It should be pointed out that the present invention is not limited to the above embodiments, and any changes made under the enlightenment of the present invention, which have the same or similar technical solutions as the present invention, shall fall within the protection scope of the present invention.

Claims

1. A method for patching and lining a ladle, characterized in that: Here are the steps: When the ladle is running to the safety line, the residual steel slag on the surface of the ladle is cleaned after it comes off the line, and then high-strength bonding plastic is applied to make the surface coated with high-strength bonding plastic smooth; then short bricks are laid layer by layer from bottom to top and squeezed tightly; after the construction is completed, the ladle is routinely baked and put into use; every time it comes off the line, it is repeatedly patched and lined, and the maintenance cycle is repeated.

2. A method for patching and lining a ladle as claimed in claim 1, characterized in that: The high-strength bonding plastic material is composed of the following components in parts by mass: 20-60% granular material and 20-45% fine powder. The material of the granular material and the fine powder is the same as the material of the position to be repaired, and the rest is additives, which are composed of three parts: plasticizer, reinforcing agent and recarburizer, plus 8-30% carbon binder.

3. A method for patching and lining a ladle as claimed in claim 2, characterized in that: The fine powder has a particle size of ≤0.15 mm, of which particles ≤10 μm are not less than 5%.

4. A method for patching and lining a ladle as claimed in claim 2, characterized in that: The reinforcing agent is one of silicon powder, aluminum powder, chromium powder, titanium powder or nickel powder, the plasticizer is one of trioctyl phosphate, dioctyl phthalate or soft clay, the recarburizer is one of colloidal sulfur, paraformaldehyde or hexamethylenetetramine, and the carbon binder is phenolic resin, furan resin, asphalt binder or a combination thereof.

5. The method for patching and lining a ladle according to claim 1, characterized in that: The method for applying the high-strength adhesive plastic to make the surface smooth is: taking the thickest part of the residual bricks in the ladle as the reference, the thickness of the high-strength adhesive plastic layer applied there is 0.5-2mm; The coating thickness is determined according to the size of the recesses in other parts to ensure a smooth and flat overall surface.

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