JP2023088138A - mud material - Google Patents

Abstract

A mud material is provided that satisfies three required properties in good balance: securing of hole depth, suppression of hole breakage, and suppression of hole enlargement.
The mud material comprises a refractory material containing carbon black, a binder comprising tars and a resin, and a curing accelerator for the resin, added and kneaded. The content of carbon black is 5% by mass or more and 12% by mass or less in 100% by mass of the refractory material, and the amount of the binder added is 12% by mass or more and 22% by mass or less in terms of the external weight of 100% by mass of the refractory material. The amount of the curing accelerator added is 1% by mass or more and 4% by mass or less with respect to 100% by mass of the resin, and the mass ratio of the resin to the tar (resin/tar) is 1 or more and 4 or less.
[Selection figure] None

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mud material that is press-fitted into a tap hole of a blast furnace to close the tap hole.

In the operation of a blast furnace, the tap hole is closed by press-fitting a mud material into the tap hole after the completion of tapping. Then, when the iron is tapped after a predetermined time (usually 2 to 5 hours) has passed, a runner is formed by drilling the mud material that has been fired by the heat of the furnace until then. When forming runners by drilling the mud material in this way, it is necessary to ensure that the runners have a certain length or more. The length of such a runner is called the hole depth.

In addition, during the formation of the runner by the drill, the mud material may fall off and molten iron or slag may flow into the runner from a portion different from the runner. In such a case, the tip of the drill wears out and cannot be drilled. This phenomenon is called piercing.

Further, in recent years, there has been a demand for extending the tapping time during tapping, so it is necessary to prevent the runner from being eroded and enlarged by molten iron or slag during tapping. Enlargement of the runner due to scraping by molten iron or slag during tapping is called hole enlargement. In addition, in order to extend the tapping time, it is necessary to suppress not only hole enlargement but also hole breakage and secure a hole depth.

By the way, the basic structure of the mud material is a kneaded refractory material obtained by adding a binder to a refractory material and kneading them. Further, a tar-based mud material using tars as a binder and a resin-based mud material using a resin are known. Mud materials using resin together are also known.
Tars have high spreadability, but it is difficult to obtain strength at low temperatures when filled. On the other hand, resin exhibits high strength but low spreadability. Thus, tars and resins have mutually contradictory advantages and disadvantages. Therefore, if tars and resins are used together as a binder, the disadvantages of one can be compensated for by the advantages of the other, making it an excellent mud material. is likely to be realized.

However, simply using a combination of tars and resin as a binder is not sufficient to satisfy the three required properties of securing the above-mentioned pore depth, suppressing piercing, and suppressing pore enlargement in a well-balanced manner. As a result, the extension of the tapping time was not sufficient.

JP 2008-100886 A

The problem to be solved by the present invention is to provide a mud material that satisfies three required properties in good balance: securing of hole depth, suppression of hole breakage, and suppression of hole enlargement.

The inventors of the present invention conducted repeated tests and studies on the composition of the mud material in order to satisfy the above-mentioned three required characteristics in a well-balanced manner in the mud material using a combination of tars and resin as a binder. It is important to keep the mass ratio of the resin and tars in a specific range, add an appropriate amount of curing accelerator for the resin, and keep the content of carbon black in the refractory material within a specific range. Found it.

That is, according to one aspect of the present invention, the following mud material is provided.
A mud material obtained by kneading a refractory material containing carbon black with a binder made of tars and a resin and a curing accelerator for the resin,
The content of the carbon black is 5% by mass or more and 12% by mass or less as a proportion of 100% by mass of the refractory material,
The amount of the binder to be added is 12% by mass or more and 22% by mass or less in terms of the external amount with respect to 100% by mass of the refractory material,
The amount of the curing accelerator to be added is 1% by mass or more and 4% by mass or less as an external amount with respect to 100% by mass of the resin,
The mud material, wherein the mass ratio of the resin and the tar (resin/tar) is 1 or more and 4 or less.

According to the present invention, it is possible to provide a mud material that satisfies three required properties in good balance: securing of hole depth, suppression of hole breakage, and suppression of hole enlargement.

The basic composition of the mud material of the present invention is obtained by kneading a refractory material containing carbon black with a binder consisting of tars and resin, and a curing accelerator for the resin. In order to satisfy the above-mentioned three required characteristics in a well-balanced manner, the mud material should spread well into the furnace when filled, exhibit strength immediately after filling, and be resistant to erosion by hot metal and slag. From this point of view, a specific configuration as a mud material is specified.

First, since the mud material of the present invention uses both tars and resins as binders, it develops strength earlier than when only tars are used, and expands during filling more quickly than when only resins are used. Good nature. By setting the mass ratio of the resin and the tar (resin/tar) to 1 or more and 4 or less, strength expression and developability are balanced. In addition, since a hardening accelerator for resin is added, corrosion resistance to hot metal and slag (hereinafter referred to as "corrosion resistance") is improved. Furthermore, by including an appropriate amount of carbon black in the refractory material, it is possible to improve spreadability while suppressing deterioration in corrosion resistance. More specific description will be given below.

In the mud material of the present invention, the refractory material contains 5% by mass or more and 12% by mass or less of carbon black. If the carbon black content is less than 5% by mass, the expandability is insufficient and the hole depth cannot be ensured. On the other hand, when the content of carbon black exceeds 12% by mass, corrosion resistance is remarkably lowered and pore enlargement is remarkably caused. The content of carbon black is preferably 5% by mass or more and 9% by mass or less based on 100% by mass of the refractory material. From the viewpoint of ensuring sufficient spreadability, the particle size of carbon black is preferably 0.075 mm or less.

Refractory materials other than carbon black include alumina siliceous raw materials such as roseite, mullite, kaolin, clay, chamotte, sericite, sillimanite, andalusite, bauxite, diaspore, and the like, as well as general mud materials. Alumina raw materials such as sand shale, fused alumina, sintered alumina, calcined alumina, sintered spinel, and fused spinel, siliceous raw materials such as silica, silica flour, and fused silica, scale graphite, earthy graphite, coke and other carbonaceous raw materials, and in addition, one or more selected from the group consisting of silicon carbide, silicon nitride, silicon iron nitride, zircon, zirconia, magnesia, chromium ore, dolomite clinker, lime, ferrosilicon, and pellets. can be done.

For refractory materials other than carbon black, the particle size is adjusted to coarse, medium, and fine grains for the purpose of obtaining a densely packed structure and good workability. be done. Specifically, the refractory material has a particle size of 10 to 30% by mass, and a particle size of 0.075 mm or less, measured using a standard sieve specified in JIS-Z8801. % is preferably adjusted so that particles having a particle size of more than 0.075 mm and 1 mm or less constitute the remainder. A plain weave sieve is used in the particle size measurement of the particles constituting the mud material using the standard sieve of JIS-Z8801. Further, the sieving test is performed in accordance with JIS-Z8815, and the test method is dry mechanical sieving.

The mud material of the present invention is obtained by adding a binder composed of tars and resin, and a resin hardening accelerator to the above-described refractory material and kneading the mixture. The amount of the binder added is 12% by mass or more and 22% by mass or less in terms of external weight with respect to 100% by mass of the refractory material. If the amount of the binder added is less than 12% by mass, the development of the strength of the mud material is delayed, so that the holes are likely to break and it becomes difficult to extend the depth of the holes. If the amount of the binder added exceeds 22% by mass, the structure of the mud material becomes porous at high temperatures, and the durability of the mud material against hot metal and slag is poor because a large amount of tars volatilizes after combustion. Pore enlargement is more likely to occur.
In the present invention, when a compatible solvent that dissolves both the tars and the resin or a conventionally used resin solvent is used, the amount of the compatible solvent or resin solvent added is included in the amount of the binder added. More specifically, it shall be included in the amount of resin added. In other words, the compatible solvent and resin solvent are included in the resin. Therefore, in the mud material of the present invention, the binder consists essentially of tars and resin.

In the mud material of the present invention, the compatible solvent can be, for example, a mixture of polyhydric alcohol and dicarboxylic acid methyl ester. As the polyhydric alcohol, for example, one or more selected from the group consisting of ethylene glycol such as monoethylene glycol, diethylene glycol and triethylene glycol, propylene glycol, polypropylene glycol, and glycerin can be used. As the dicarboxylic acid methyl ester, for example, one or more selected from the group consisting of dimethyl malonate, dimethyl succinate, dimethyl glutarate, and dimethyl adipate can be used.

In addition, the amount of the resin curing accelerator to be added is 1% by mass or more and 4% by mass or less in terms of the amount added relative to 100% by mass of the resin. If the amount of the hardening accelerator added is less than 1% by mass, the densification of the mud material becomes insufficient and the corrosion resistance decreases, resulting in conspicuous pore enlargement. On the other hand, if the amount of the curing accelerator added exceeds 4% by mass, the resin cures too quickly and the hole depth cannot be ensured. Considering the stability of the mud material in the mud gun and the structural stability in hot conditions, the amount of the curing accelerator added to the resin should be 1.4% by mass or more and 2% by mass or less based on 100% by mass of the resin. is preferred. Hexamine, epoxy resin, isocyanate, or the like can be used as a resin curing accelerator.

In the mud material of the present invention, the mass ratio (resin/tar) of resin and tar in the binder is 1 or more and 4 or less. If the mass ratio is less than 1, the strength development after filling is insufficient, and piercing is likely to occur. On the other hand, if the mass ratio is more than 4, the spreadability is lowered, and the hole depth cannot be secured, and the corrosion resistance is also lowered, so that the holes are likely to expand. The mass ratio is preferably 1 or more and 2.4 or less.

Examples of resins include phenol resins, furan resins, urea resins, melamine resins, xylene resins, and epoxy resins. Both novolak type and resol type phenol resins can be used. When a phenol resin is used as the resin, it is preferable to use hexamine as the curing accelerator.
On the other hand, as tars, for example, one or more selected from the group consisting of coal tar, petroleum tar, wood tar, shale tar (oil produced by dry distillation of oil shale), asphalt, and pitch can be used. . As the tars, it is preferable to use those having a viscosity of 200 mPa·s or more and 2000 mPa·s or less at 60°C. If the viscosity at 60° C. is less than 200 mPa·s, the amount of residual carbon after combustion of tars is reduced, and the resistance of the mud material to hot metal and slag is poor, and pore enlargement is likely to occur. In addition, when the viscosity at 60°C exceeds 2000 mPa·s, it is necessary to increase the amount of tars added to the mud material in order to obtain strength, compared to those with a viscosity at 60°C of 200 mPa·s or more and 2000 mPa·s or less. be. Since many tars volatilize after combustion, the structure of the mud material becomes porous at high temperatures, and the resistance of the mud material to hot metal and slag is poor, and pores are likely to expand.

As described above, in the mud material of the present invention, the mass ratio of the resin and tars in the binder is set within a specific range, a suitable amount of resin curing accelerator is added, and carbon black in the refractory material is added. By setting the content of is within a specific range, it is possible to satisfy the three required properties in a well-balanced manner: ensuring hole depth, suppressing hole breakage, and suppressing hole enlargement.

The strength development, plasticity and corrosion resistance of the mud material of each example having the composition shown in Table 1 were evaluated, and a comprehensive evaluation was made based on these evaluation results.
In addition, in Table 1, refractory materials other than carbon black include pyrophyllite, silicon carbide, electrofused alumina, clay, and the like, similarly to general mud materials. A novolac type phenol resin was used as the resin, and hexamine was used as the curing accelerator. Tars having a viscosity of 200 mPa·s or more and 400 mPa·s or less at 60° C. were used. According to JISZ8803, the viscosity was measured using a Brookfield viscometer for tar at 60°C.

Evaluation methods and evaluation criteria for strength development, plasticity, corrosion resistance, and comprehensive evaluation are as follows.
<Strength expression>
An electric furnace under a nitrogen atmosphere was previously heated to 300° C., and a φ35×30 mm mud material was placed in the furnace, taken out after 35 minutes, and strength was measured with a compression tester. Then, when the strength measurement value is 20 MPa or more and 40 MPa or less, ◎ (excellent), 3 MPa or more and less than 20 MPa, O (good), less than 3 MPa, x (low) (poor), and more than 40 MPa, x. (High) (Poor). The higher the measured strength value, the more the strength is developed immediately after filling with the mud material, which contributes particularly to the suppression of hole breakage.

<Plasticity>
1 kg of the mud material was heated at 250° C. for 3 hours, and the extrusion pressure value was measured with a Marshall tester. Then, when the extrusion pressure value was 3 MPa or less, it was evaluated as ◯ (good), and when it exceeded 3 MPa, it was evaluated as x (poor). The lower the extrusion pressure value, the better the plasticity, and the better the spreadability into the furnace when the mud material is filled, which contributes particularly to ensuring the hole depth.

<Corrosion resistance>
After molding the mud material under pressure at 7 MPa, a test piece obtained by baking at 500° C. was lined in a small rotary furnace using blast furnace slag as an erosion agent, and an erosion test was performed at 1600° C. for 5 hours. rice field. The erosion agent was replaced (10 times) every 30 minutes during the erosion test. After the corrosion test, the eroded dimension (maximum eroded portion) of the test piece was measured, and the corrosion resistance index was calculated with the eroded dimension of Comparative Example 2 being 100. When the corrosion resistance index was less than 70, it was evaluated as ⊚ (excellent); The smaller the corrosion resistance index, the better the corrosion resistance, which contributes particularly to the suppression of pore enlargement.

<Comprehensive evaluation>
◎ (excellent) when both the evaluation of strength development and corrosion resistance are ◎ (excellent) and the evaluation of plasticity is 〇 (good), and at least one evaluation of strength development and corrosion resistance is 〇 (good). And when there is no evaluation of × (poor) in the evaluation of strength development, plasticity and corrosion resistance, 〇 (good), and when at least one evaluation of strength development, plasticity and corrosion resistance is × (poor) (defective).

In Table 1, Examples 1 to 3 are all mud materials within the scope of the present invention, and the overall evaluation was ⊚ (excellent) or ◯ (good), and good results were obtained. That is, according to the mud materials of Examples 1 to 3, it can be said that the three required properties of securing hole depth, suppressing hole breakage, and suppressing hole enlargement can be satisfied in a well-balanced manner. Among them, Example 1, in which the content of carbon black, the amount of curing accelerator added, and the mass ratio of resin and tar (resin/tar) are all within the preferable range, received an overall evaluation of ⊚ (excellent). , gave particularly good results.

Comparative Example 1 is an example in which the carbon black content is too small. Evaluation of plasticity was x (poor). Therefore, the hole depth cannot be ensured.
On the other hand, Comparative Example 2 is an example in which the content of carbon black is too large. The evaluation of corrosion resistance was x (poor). Therefore, pore enlargement cannot be suppressed.

Comparative Example 3 is an example in which the amount of binder added is too small. The evaluation of strength development was x (low) (poor) and the evaluation of plasticity was x (poor). Therefore, it is not possible to suppress the breakage of the hole, and it is also impossible to ensure the depth of the hole.
On the other hand, Comparative Example 4 is an example in which the amount of binder added is too large. The evaluation of corrosion resistance was x (poor). Therefore, pore enlargement cannot be suppressed.

Comparative Example 5 is an example in which the mass ratio (resin/tars) is too low. The evaluation of strength development was x (low) (poor). Therefore, breakage cannot be suppressed.
On the other hand, Comparative Example 6 is an example in which the mass ratio (resin/tars) is too high. The evaluation of strength development was x (high) (poor) and the evaluation of plasticity and corrosion resistance was x (poor). Therefore, the hole depth cannot be ensured, and hole breakage and hole enlargement cannot be suppressed.

Comparative Example 7 is an example in which the amount of the curing accelerator added is too small. The evaluation of corrosion resistance was x (poor). Therefore, pore enlargement cannot be suppressed.
On the other hand, Comparative Example 8 is an example in which the amount of the curing accelerator added is too large. The evaluation of strength development was x (high) (poor) and the evaluation of plasticity was x (poor). Therefore, the hole depth cannot be ensured.

Claims (3)

A mud material obtained by kneading a refractory material containing carbon black with a binder made of tars and a resin and a curing accelerator for the resin,
The content of the carbon black is 5% by mass or more and 12% by mass or less as a proportion of 100% by mass of the refractory material,
The amount of the binder to be added is 12% by mass or more and 22% by mass or less in terms of the external amount with respect to 100% by mass of the refractory material,
The amount of the curing accelerator to be added is 1% by mass or more and 4% by mass or less as an external amount with respect to 100% by mass of the resin,
The mud material, wherein the mass ratio of the resin and the tar (resin/tar) is 1 or more and 4 or less. 2. The mud material according to claim 1, wherein said tar has a viscosity at 60[deg.] C. of 200 mPa.s or more and 2000 mPa.s or less. 3. The mud material according to claim 1, wherein said resin is a phenolic resin and said curing accelerator is hexamine.