JP4040828B2 - Tar mud - Google Patents

Description

【００２１】
【発明の効果】
以上説明したように本発明によれば、作業性を損なうことなく、タール添加量の低減がはかれるので、開孔性と強度（使用時の耐用性）に優れたタールマッド材を提供することが可能となる。
【図面の簡単な説明】
【図１】タール添加量とタールマッドの気孔率との関係を示すグラフである。
【図２】作業性値とタール添加量の関係を示すグラフである。
【図３】タール添加量／比表面積と作業性値との関係を示すグラフである。
【図４】カーボンブラックとシリカヒュームの配合比率と熱間曲げ強さとの関係を示すグラフである。
【図５】タール添加量／ＢＥＴ比表面積と作業性値との関係を示すグラフである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tar mud material used for closing a blast furnace outlet, and particularly provides a mud material having high strength and good workability at the time of closing (hereinafter simply referred to as “workability”).
[0002]
[Prior art]
In general, the blast furnace outlet for discharging pig iron and slag is filled with a plugging material (hereinafter referred to as `` mud material '') consisting mainly of an indeterminate refractory via a plugging machine (mud gun) after discharging and dredging. It is blocked by filling.
The properties required for this mud material are:
(1) Provide plasticity for filling the outlet, that is, excellent workability,
(2) Filled mud material, no formation of voids due to rapid expansion / evaporation of volatile matter, a dense filling state is maintained, and sintering is completed in a short time.
(3) At the time of unloading, it is easy to open the unloading port, especially drilling, that is, excellent in machinability,
(4) Withstands mechanical or chemical erosion caused by contact with hot metal and hot metal that flows out during unloading and unloading, and the diameter of the unloaded hole is small.
(5) At the time of filling and firing, in the furnace and in the deep part of the tap outlet, familiarity with the old mud material that has already been fired is good, and it easily penetrates into the cracked part and is excellent in maintaining depth and preventing side holes. Excellent adhesion
Etc.
[0003]
For such a blast furnace outlet closing mud material, coal tar (hereinafter simply abbreviated as “tar”) is added as a binder (sintered material) as disclosed in JP-A-52-33907. Tar mud material is common. The reason why such a tar mud material is adopted is that, besides the reason that tar is cheap, the properties required for the mud material, that is, workability and machinability after firing are excellent.
[0004]
By the way, tar contributes to the fluidity at the time of press-fitting, and plays a role as a binder that forms a carbon bond and develops strength after firing. On the other hand, this tar has the property of foaming in the carbonization process up to 600 ° C. For this reason, it is known that the tar mud material undergoes volume expansion immediately after being press-fitted into the tap outlet, and the amount of expansion increases as the tar content increases (the volatile content increases). In other words, in the conventional tar mud material, the relationship between the tar content in the mud material and the porosity due to volume expansion (porosity of the 1400 ° C calcined mud) is generally as shown in FIG. If it is 17% or more, the porosity of the tar mud material increases as the tar content increases. As described above, when the tar content is 17% or more, it is caused by excessive tar foaming and void formation due to volatilization. The reason why the porosity increases even when the tar content is less than 17% is considered that the tar mud material was already poorly filled before firing.
[0005]
As shown in FIG. 1, when the amount of the tar mud material exceeds a certain amount (about 17% in FIG. 1), the volume expansion of the mud material due to the foaming of the tar increases, and the porosity increases. For this reason, the firing strength is reduced, and the resulting mud material does not push back the residue in the furnace during the closing operation of the anti-sticking, and takes it into the gap of the filled mud material. It can happen.
For this reason, in order to reduce the voids of the tar mud material and increase the firing strength, it is necessary to reduce the amount of tar as much as possible. As a proposal from such a standpoint, Japanese Patent Application Laid-Open No. 11-217264 discloses a technique for impregnating a raw material with tar in advance.
[0006]
However, in order to press-fit the tar mud material into the tap outlet, it is indispensable to impart fluidity to the tar mud material. In other words, in order to obtain the necessary firing strength as a tar mud material, it is possible to reduce the amount of tar, while on the other hand, it is necessary to increase the amount of tar rather than the press-fitting work, to solve the mutually contradicting problems. It becomes necessary.
[0007]
It is known that the fluidity of a paste-like material such as a tar mud material is improved by using a fine powdery raw material as a solid component. This is because fine powder generally exhibits fluid properties and functions as a solid lubricant. Examples of the fine powder material of the tar mud material include oxide fine powders such as silica, mullite, and alumina, clay-based fine powders, carbon-based fine powders such as carbon black, SiC, and Si ₃ N ₄ (Fe—Si ₃ N ₄ ). The use of oxide fine powder is conceivable, and some of these fine powder raw materials have already been used as raw materials for tar mud materials.
However, in general, the use of a large amount of fine powder often leads to an increase in the amount of tar added, which also causes the above-described problems caused by the increase in the amount of tar.
[0008]
[Problems to be solved by the invention]
This invention makes it a subject to solve the problem mentioned above which the conventional tar mud material has.
That is, the objective of this invention is providing the tar mud material which has workability | operativity and intensity | strength by adding tar effectively. Specifically, the tar mud material contains a sufficient amount of tar that matches the characteristics of the solid particles, thereby maintaining the fluidity (workability) of the tar mud material and forming a dense packed structure. Thus, it is to provide a tar mud material having sufficient strength.
[0009]
[Means for Solving the Problems]
In the above prior art, when using a large amount of fine powder, the function as a solid lubricant has not been quantitatively grasped so far, as the cause of increasing the amount of tar added (content) It is possible that
Accordingly, the inventors conducted detailed experiments and examinations focusing on the relationship between the solid component, particularly the action as a solid lubricant of the fine powder raw material, and the specific surface area, and the appropriate amount of tar added according to the characteristics of the solid component. It was found that (content) exists. In addition, the inventors have found a fine powder material that has a large effect as a solid lubricant and that contributes effectively to a reduction in the amount of added tar. It was confirmed that the tar mud material manufactured based on such knowledge is well controlled in workability and sinterability, and has both reduced load during opening and improved durability.
[0010]
The present invention completed based on such knowledge,
(1) A tar mud material used to occlude the blast furnace taphole, a specific surface area of the solid component containing the content of the tar contained in the tar mud material, silica fume and / or carbon black ratio, and obstructive workability value, the following (1), tar mud material characterized in that it meets the expression (2) conditions.
Record
3500−9.55 × 10 ⁴ x ≦ y / 9.8 ≦ 4000−9.55 × 10 ⁴ x …… (1)
100 ≦ y / 9.8 ≦ 400 (2)
However,
x: (tar content (% by mass) / (specific surface area determined by BET method of solid component (m ² / g)) in tar mud material
y: Workability value obtained by marshall test (N)
[0011]
(2) In the inventions of the above (1), the solid component, it is preferable to use those containing no clay fines.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The inventors studied to reduce the amount of tar contained in the tar mud material to the minimum amount necessary for ensuring strength and workability. First, tar muds containing various raw materials and solid components composed of particle size distributions were prototyped, and the relationship between the tar content and workability values was investigated. As a result, as shown in FIG. 2, it was clarified that the workability value largely varied even under the same tar content although the workability value generally decreased when the tar content was increased. .
Therefore, as a parameter that can comprehensively evaluate the influence of tar acting as a fluid lubricant and fine powder acting as a solid lubricant, the specific surface area determined by the BET method of tar content and solid components (mostly less than 74 μm) Since it is determined by the solid component of the particle size, the relationship with the workability value was investigated using the ratio of physical quantities that can quantitatively evaluate the contribution of fine powder.
[0013]
As a result, the workability value y is given by
y / 9.8 = 4300−9.55 × 10 ⁴ x …… (a)
It was confirmed that there is a relationship. here,
x: (tar content in tar mud material (%)) / (specific surface area (m ² / g) obtained by BET method of solid component) y: work of occlusion determined by Marshall test (70 ° C.) It is a sex value (N). The above formula (a) is a formula that holds for a so-called conventional blending design in which no special consideration is given to the raw material of the solid component.
[0014]
Therefore, the inventors investigated how the relationship between the tar content / specific surface area and the workability value changes when the raw material of the conventional solid component is changed to one having further lubricity. did.
Specifically, the fine powder of 74 μm or less, which has a large role as a solid lubricant, is changed from conventional raw materials to carbon black, silica fume , kaolin clay, rholite, alumina, SiC, Si ₃ N _4, etc. Tar mud material was manufactured and the workability value was investigated. As a result, in the tar mud material using carbon black and silica fume as a solid component, a relationship having a proportional constant similar to that of the conventional material is seen between the tar content / specific surface area and the workability value. It was found that the shift to the lower workability value side than the above equation (a). And when such a highly lubricious solid component was utilized effectively to the maximum, a range represented by the following formula was obtained.
3500−9.55 × 10 ⁴ x <y / 9.8 <4000−9.55 × 10 ⁴ x ...... (b)
[0015]
FIG. 3 shows the results obtained by the experiment in which the fine powder raw material of 74 μm or less is changed together with the above formulas. In FIG. 3, most of the conventional materials (containing SiC: 15 to 35% in the fine powder raw material) are on the right side of the formula (a), but the experimental points using the high lubricant as a solid component (all are In the fine powder raw material, 9 to 15% of a lubricant is added) and is shifted to the lower left to satisfy the formula (b).
[0016]
From the above, according to the required workability value y, the parameter x, that is, the ratio between the tar content and the specific surface area of the solid component described above is
3500−9.55 × 10 ⁴ x ≦ y / 9.8 ≦ 4000−9.55 × 10 ⁴ x ...... (1)
If it is adjusted to a range that satisfies the above relationship, tar addition can be effectively used while maintaining strength, and particularly by using a solid component having a lubricating action within the above range, tar can be used very effectively. Can do.
However, if this workability value is less than 100 kg, hot metal tends to be caught when filling with an actual mud gun, and wear of the spout hole tends to increase due to poor filling (leakage), while 400 kg is reduced. If it exceeds, the ability of the mud gun will be exceeded, and there will be a tendency for frequent filling failures such as swinging off without being pushed out, so the workability value y must also satisfy the following equation.
100 ≤ y / 9.8 ≤ 400 ...... (2)
Therefore, when these tar content, specific surface area and workability value satisfy both of the above formulas (1) and (2), a dense packed structure can be obtained while maintaining workability. Is defined as a range to be satisfied by the present invention.
[0017]
The tar mud material according to the above-mentioned invention consists of tar and a solid component. The solid component is a mixture of coarse aggregate exceeding 74 μm and fine powder of 74 μm or less. Of these, the amount of fine powder of 74 μm or less is 40 to 40% of the solid component in terms of workability and strength (fillability). It is desirable to occupy 60%. Furthermore, the amount of carbon black and / or Shirikahiyumu having high lubricity, it is preferable to 8-75% containing organic in the following fines 74 .mu.m. On the other hand, as shown in FIG. 3, the clay-like material has a relatively small lubricating effect as compared with carbon black and silica fume, and therefore is not actively contained in a fine powder of 74 μm or less.
In addition, as an aggregate exceeding 74 micrometers, it is preferable that a carbon material, rholite, a band shale, a silica, an alumina, a mullite, a spinel, magnesia etc. are included. Further, in the environment where the mud material is used, tar pitch can be added for the purpose of adjusting fluidity according to the ability of the mud gun.
[0018]
In actual use, control of sinterability and a certain degree of strength maintenance are required. In such a case, it is possible to improve the strength by replacing the carbon black with silica fume. It is good to change. FIG. 4 shows the effect of the use ratio of carbon black and silica fume on strength (hot bending strength at 1400 ° C.).
[0019]
【Example】
A mud material was prepared according to the formulation described in Table 1.
In accordance with the present invention, a combination of carbon black having solid lubricity and silica fume (invention example), and for comparison, a fine powder portion mainly composed of kaolin clay (Comparative Example 1) and alumina ultrafine powder mainly. A sample (Comparative Example 2) was prototyped and evaluated.
Table 1 shows the BET specific surface area, workability value, and tar content (addition amount) of the prototype. In the inventive examples, it was possible to obtain a low workability value with a low tar amount as compared with the comparative examples. FIG. 5 shows the relationship between the tar content / BET specific surface area and the workability value. When using ultra-fine alumina powder, the workability depends on the amount of tar and, more precisely, the coating thickness of tar, but the combination of carbon black and silica fume dominates the effect of solid lubrication and is less The workability value could be reduced even with the tar content.
Further, the mud material prepared by blending as described above was baked at 1400 ° C. and the porosity was measured. As a result, the same result as in FIG. A porosity of 21% or less was obtained, which was practically preferable.
[0020]
[Table 1]

[0021]
【The invention's effect】
As described above, according to the present invention, since the tar addition amount can be reduced without impairing workability, it is possible to provide a tar mud material excellent in pore opening property and strength (durability during use). It becomes possible.
[Brief description of the drawings]
FIG. 1 is a graph showing the relationship between the amount of tar added and the porosity of tar mud.
FIG. 2 is a graph showing the relationship between workability value and tar addition amount.
FIG. 3 is a graph showing the relationship between tar addition amount / specific surface area and workability value.
FIG. 4 is a graph showing the relationship between the blending ratio of carbon black and silica fume and hot bending strength.
FIG. 5 is a graph showing the relationship between tar addition amount / BET specific surface area and workability value.

Claims (2)

A tar mud material used for closing a blast furnace outlet, the ratio of the tar content contained in the tar mud material and the specific surface area of the solid component containing silica fume and / or carbon black, A tar mud material characterized in that the blockage workability value satisfies the conditions of the following formulas (1) and (2).
Record
3500−9.55 × 10 ⁴ x ≦ y / 9.8 ≦ 4000−9.55 × 10 ⁴ x …… (1)
100 ≦ y / 9.8 ≦ 400 …… (2)
However,
x: (tar content (% by mass) / (specific surface area determined by BET method of solid component (m ² / g)) in tar mud material
y: Workability value obtained by marshall test (N) The solid Ingredients are tar mud material according to claim 1, characterized in that use containing no clay fines.

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