Mud material

Abstract

In mud materials used by filling a mud gun using a vibration method, sufficient fluidity is provided when the mud material is poured from the hopper into the mud gun for filling, and the density of the mud material structure that seals the taphole is improved. [Solution] The mud material comprises a refractory material and a binder, the refractory material contains 2 to 8% by mass of carbon black, and the particle size composition of the refractory material is 15% by mass or less (including 0) of particles with a particle size of 1 mm or more and less than 3 mm, and 60 to 85% by mass of particles with a particle size of less than 0.075 mm.

Description

Technical Field

[0001] The present invention relates to a mud material that is pressure-filled into the taphole of a blast furnace to block the taphole.

Background Art

[0002] The mud material comprises a refractory material and a binder. For example, in Patent Document 1, Patent Document 2, etc., a mud material is disclosed in which a binder such as tar is added to a refractory material containing oxide materials such as vermiculite, silica, kyanite, alumina, chamotte, and clay, non-oxide materials such as silicon carbide and ferrosilicon nitride, and carbonaceous materials such as coke and graphite. In such a mud material, clay is blended in the fine powder portion of the refractory material to impart plasticity. Also, a technique is known in which the amount of the binder is reduced by using carbon black together with clay to obtain a high-density material (see, for example, Patent Document 3). Further, a technique is known in which the amount of the binder is reduced by using an ultrafine powder material having an average particle size of 1 μm or less (see, for example, Patent Document 4). However, there is little knowledge about the particle size composition of the refractory material.

[0003] On the other hand, the pressure filling of the mud material into the taphole of the blast furnace is performed using a mud gun. As a method of filling the mud gun with the mud material, a method of automatically filling from a hopper to the mud gun using a vibrating device (hereinafter referred to as the "vibrating method") is known (see, for example, Patent Document 5 and Patent Document 6).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

[0005] One of the required properties for mud material is to improve the density of the mud material structure that seals the taphole. This is because improved mud material density improves corrosion resistance to slag and molten iron. In this regard, Patent Document 7 states that tar used as a binder contains a large amount of volatile components, which causes a decrease in the density of the mud material structure. In other words, if the amount of tar can be reduced, the density of the mud material structure can be improved. Furthermore, Patent Document 7 states that it is possible to reduce the amount of tar by using carbon black as the refractory material for the mud material. This is because carbon black has sliding properties, and can impart sliding properties when the mud material is press-fitted into the taphole, thus serving as a substitute for tar.

[0006] However, when the mud material containing carbon black described in Patent Document 7 is applied to the vibration method described in Patent Documents 5 and 6, a problem arises in that the mud material does not fill the mud gun when it is poured from the hopper to the mud gun. This is because the mud material with added carbon black is highly viscous due to the viscosity characteristic of carbon black, and sufficient fluidity cannot be obtained in the mud material when it is poured from the hopper to the mud gun.

[0007] One might think that using a low-viscosity binder (for example, low-viscosity tar) would solve this problem. However, simply adding a low-viscosity binder would increase the volatile content of the binder and raise the porosity, thus reducing the density of the mud material structure. Although Patent Documents 5 and 6 attempt improvements from the perspective of binder properties, the effects have not been entirely satisfactory.

[0008] Therefore, the problem that this invention aims to solve is to provide sufficient fluidity to the mud material used when it is poured from the hopper into the mud gun by a vibration method, and to improve the density of the mud material structure that closes the taphole. [Means for solving the problem]

[0009] According to one aspect of the present invention, the following mud material is provided. The mud material is poured from the hopper into the mud gun by the vibration of the vibrating device. It contains fire-resistant material and binder, The aforementioned fire-resistant material contains 2 to 8% by mass of carbon black. The refractory material has a particle size composition of 15% by mass or less with a particle size of 1 mm or more and less than 3 mm, and 60 to 85% by mass with a particle size of less than 0.075 mm, and is a mud material. [Effects of the Invention]

[0010] According to the present invention, by limiting the carbon black content in the refractory material to a specific range and limiting the particle size composition of the refractory material, it is possible to provide sufficient fluidity when pouring and filling the material from the hopper to the mud gun using a vibration method, and to improve the density of the mud material structure that closes the taphole. [Modes for carrying out the invention]

[0011] The mud material of the present invention comprises a fire-resistant material and a binder. The refractory material contains at least 2 to 8 mass% of carbon black. If the carbon black content is less than 2 mass%, sufficient sliding properties are difficult to obtain when the mud material is injected into the tapping hole using a mud gun, resulting in a decrease in the density of the mud material structure. When the density of the mud material structure decreases, the mud material becomes more susceptible to melting. As a result, it becomes impossible to ensure sufficient tapping time. On the other hand, if the carbon black content exceeds 8 mass%, the viscosity of the mud material increases, and sufficient fluidity cannot be obtained when the mud material is flowed from the hopper to the mud gun using a vibration method. As a result, it becomes impossible to fill the mud material from the hopper to the mud gun. The carbon black content is preferably 4 to 8 mass%. The specific types of carbon black are not limited in any way, and examples include furnace black, thermal black, acetylene black, channel black, lamp black, and Ketjenblack S.

[0012] The mud material of the present invention contains, in addition to carbon black, alumina, alumina-silica, silica, magnesia, magnesia-calcia, spinel, carbides, nitrides, carbon, coke, clay, various metals, and other refractory materials that have been commonly used as refractory materials in conventional mud materials. The content of these materials is adjusted as appropriate.

[0013] In the present invention, the particle size composition of the refractory material is such that particles with a particle size of 1 mm or more and less than 3 mm account for 15% by mass or less (including 0), and particles with a particle size of less than 0.075 mm account for 60 to 85% by mass. If the particle size composition of the refractory material exceeds 15% by mass, the relative decrease in particles with a particle size of less than 1 mm reduces the fluidity (hereinafter referred to as "vibration fluidity") when filling the mud gun from the hopper using the vibration method, resulting in poor filling. Similarly, if the percentage of particles with a particle size of less than 0.075 mm is less than 60% by mass, vibration fluidity decreases, resulting in poor filling. On the other hand, if the percentage of particles with a particle size of less than 0.075 mm exceeds 85% by mass, there is an excess of fine powder with a particle size of less than 0.075 mm, which reduces the density of the mud material structure. It is preferable that the percentage of particles with a particle size of less than 0.075 mm in the particle size composition of the refractory material is 70 to 85% by mass.

[0014] In this invention, particle size refers to the size of the sieve opening when refractory material particles are separated by sieving. For example, a refractory material with a particle size of less than 3 mm is a refractory material that can pass through a sieve with a 3 mm opening, and a refractory material with a particle size of 1 mm or more is a refractory material that cannot pass through a sieve with a 1 mm opening.

[0015] In the mud material of the present invention, tars or resins that have been conventionally used as binders for mud materials can be used as the binder. As for tars, one or more selected from the group consisting of coal tar, petroleum tar, wood tar, oxalite tar (oil produced by the dry distillation of oil oxalite), asphalt, and pitch can be used. As for resins, examples include phenol resin, furan resin, urea resin, melamine resin, xylene resin, epoxy resin, etc. Both novolac type and resol type phenol resins can be used. In addition, tars and resins can be used in combination.

[0016] In the mud material of the present invention, the binder addition rate is adjusted as appropriate, similar to conventional mud materials, so that the extrusion pressure value of the mud material measured by a Marshall testing machine falls within a predetermined range. An example of such an addition rate range is 17 to 22% by mass.

[0017] The mud material of the present invention is filled into the mud gun from the hopper by a vibration method. The filling method itself by the vibration method is known as disclosed in Patent Document 5 above, and the mud material is automatically filled from the hopper into the mud gun using a vibration device and, if necessary, a heat preservation device. The vibration force of the vibration device used in the vibration method is generally about 1.6 kN (about 160 kgf), and the heat preservation temperature of the mud material during filling is about 50 to 80°C.

[0018] In addition, the mud material of the present invention preferably has a vibration flow value (hereinafter simply referred to as "vibration flow value") at 50°C of 130 mm or more. Here, the "vibration flow value" refers to the value measured by the following procedure. (1) Place a cylindrical metal frame with a diameter of 100 mm and a height of 60 mm heated to 50°C on the upper surface of a surface plate maintained at 50°C, and fill the sample of the mud material at 50°C into it. (2) Lift the cylindrical metal frame, and immediately apply a vibration of 6.0 G to the surface plate for 30 seconds, and measure the spread dimension of the sample. (3) The spread dimension is the length of a straight line passing through the position where the center of the cylindrical metal frame was located, and the minimum value is taken as the vibration flow value.

[0019] This vibration flow value is an index representing the fluidity, that is, the vibration fluidity, when the mud material is filled into the mud gun from the hopper by the vibration method. A vibration flow value that imparts sufficient vibration fluidity is more preferably 140 mm or more. The upper limit value of the vibration flow value is not particularly limited, but considering problems such as material separation, for example, it can be set to 200 mm as the upper limit.

Examples

[0020] Hereinafter, examples of the present invention and comparative examples thereof are shown. Table 1 shows the blending composition of the mud material in each example and the evaluation results. The evaluation items and evaluation methods for the mud material in each example shown in Table 1 are as follows. <Vibration flow value> The vibration flow value was measured using the procedure described above. As mentioned above, this vibration flow value is an index representing vibration fluidity, and was evaluated as follows: less than 130 mm was × (poor), 130 mm or more but less than 140 mm was △ (good), and 140 mm or more was ○ (excellent). <Apparent porosity> Apparent porosity was measured according to JIS2205 using samples of the mud material dried at 800°C for each example. Apparent porosity is an indicator of the density of the mud material structure, and was evaluated as follows: less than 25% was ○ (excellent), 25% to less than 27% was △ (good), and 27% or more was × (poor). <Overall Rating> The overall evaluation was as follows: ◎ (Excellent) if both evaluation results were ○, ○ (Good) if one of the two evaluation results was △ but there were no × evaluation results, and × (Poor) if at least one of the two evaluation results was ×. ◎ (Excellent) or ○ (Good) was considered a passing grade.

[0021] [Table 1]

[0022] Examples 1 to 3 show different proportions of particle size between 1 mm and 3 mm in the particle size composition of the refractory material, but all are within the scope of the present invention, and good results were obtained in both the evaluation of vibration flow value and apparent porosity. In contrast, Comparative Example 1 is an example where the proportion of particles with a particle size of 1 mm or more and less than 3 mm exceeds the upper limit of the present invention in the particle size composition of the refractory material, and the evaluation of the vibration flow value was × (poor). Therefore, there is a problem of insufficient vibration flowability resulting in poor filling.

[0023] Examples 4, 5, 2, and 6 show different proportions of particles smaller than 0.075 mm in the particle size composition of the refractory material, but all are within the scope of the present invention, and good results were obtained in both the evaluation of vibration flow value and apparent porosity. In contrast, Comparative Example 2 is an example where the proportion of particles with a particle size of less than 0.075 mm in the particle size composition of the refractory material falls below the lower limit of the present invention, and the evaluation of the vibration flow value was × (poor). Therefore, there is a problem of insufficient vibration flowability and poor filling. On the other hand, Comparative Example 3 is an example where the proportion of particles with a particle size of less than 0.075 mm in the particle size composition of the refractory material exceeds the upper limit of the present invention, and the evaluation of the apparent porosity was × (poor). Therefore, there is a problem of reduced density of the mud material structure.

[0024] Examples 7, 8, 2, and 9 represent different carbon black content levels, but all fall within the scope of the present invention, and good results were obtained in both the evaluation of vibration flow value and apparent porosity. In contrast, Comparative Example 4 is an example where the carbon black content is below the lower limit of the present invention, and the evaluation of apparent porosity was × (poor). Therefore, there is a problem of reduced density of the mud material structure. On the other hand, Comparative Example 5 is an example where the carbon black content is above the upper limit of the present invention, and the evaluation of the vibration flow value was × (poor). Therefore, there is a problem of insufficient vibration fluidity resulting in poor filling.

[0025] Example 10 is an example in which resin was used as a binder instead of tars, but it is within the scope of the present invention, and good results were obtained in both the evaluation of vibration flow value and apparent porosity.

Claims

1. The mud material is poured from the hopper into the mud gun by the vibration of the vibrating device. It contains fire-resistant material and binder, The aforementioned fire-resistant material contains 2 to 8% by mass of carbon black. The refractory material has a particle size composition of 15% by mass or less (including 0) of particles with a particle size of 1 mm or more and less than 3 mm, and 60 to 85% by mass of particles with a particle size of less than 0.075 mm.

2. The mud material according to claim 1, wherein the carbon black content in the refractory material is 4 to 6% by mass.

3. The mud material according to claim 1 or 2, wherein the particle size composition of the refractory material contains 70 to 85% by mass of particles with a particle size of less than 0.075 mm.

4. The mud material according to claim 1 or 2, wherein the vibration flow value at 50°C is 130 mm or more.

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