JPH07110793B2 - Blast furnace tap closure - Google Patents

Description

TECHNICAL FIELD The present invention relates to a plugging material for a taphole of a blast furnace.

Conventional technology and its problems With the recent enlargement of the blast furnace and severer operating conditions, the corrosion resistance (remeltability), heat resistance, wear resistance, etc. of the plugging material of the taphole to the hot metal and slag are strongly improved. Is desired. In particular, if the slag resistance is low, the amount of slag in the latter half of the tapping increases, causing rapid wear and expansion of the taphole, and at the same time, a large amount of furnace gas leaks from the enlarged taphole. The amount of slag will decrease. Therefore, the tap hole must be closed again before tapping is sufficiently performed. Such shortening of the tapping time inevitably increases the number of tappings and significantly reduces workability.

In order to solve the above-mentioned problems, an occluding material having an increased alumina content is used. The increase in alumina is
Effective in improving slag resistance. However, the occlusive material having an increased content of alumina has a drawback that it is difficult to sinter at normal temperature and time. Therefore, the closure is
According to a conventional method, even if the taphole is filled with a pineapple gun and then dried and fired, sufficient strength is not exhibited.

Further, an occluding material containing an increased amount of pigment such as silicon carbide or a carbon material is also used. Increasing the amount of silicon carbide and carbon material is optimal for improving slag resistance. However, if the amount is increased above a certain amount, the function of the binder having the clay degree is weakened, and the strength of the plugging material is lowered.

Means for Solving the Problems The present inventor has conducted extensive studies in order to solve the problems of the conventional techniques as described above, and as a result, as a raw material for the occluding material having a specific composition,
The inventors have found that the addition of a specific liquid organic binder can provide a blast furnace taphole closing material having excellent slag resistance, and have completed the present invention.

That is, the present invention includes (a) 60 to 84% by weight of carbon material, 5 to 15% by weight of silicon carbide, 4 to 15% by weight of carbon black, 2 to 8% by weight of metallic silicon, and Al ₂ O ₃ —SiO ₂ -based refractory. The present invention relates to a blast furnace taphole closing material containing 100 parts by weight of an occluding material raw material composed of 5 to 20% by weight of an aggregate and (b) 15 to 26 parts by weight of a liquid organic binder.

In the present invention, carbon materials, silicon carbide,
Carbon black, metallic silicon and Al ₂ O ₃ —SiO ₂ type refractory aggregate are used.

Although many carbon materials and silicon carbide are used in the present invention,
The decrease in strength that occurs with conventional occlusive materials does not occur. In addition to conventional materials, this is a carbon black that can impart the same level of plasticity and bonding strength as clay, and also has excellent slag resistance, and metal silicon and slag resistance that improve slag resistance and strength. Al ₂ O ₃ effective in improving the properties and suppressing the oxidation of components
This is because —SiO ₂ refractory aggregate is used and an organic binder is further added.

As the carbon material, any of ordinary carbon materials other than carbon black can be used, and examples thereof include earth-like graphite, phosphorous graphite, coal coke, petroleum coke, and electrode pulverized products. The amount of the carbon material blended is preferably about 60 to 84% by weight in the plugging material. If it is less than 60% by weight, the slag resistance of the obtained occluding material is not sufficient, and if it exceeds 84% by weight, the strength of the obtained occluding material decreases.

The content of silicon carbide is preferably about 5 to 15% by weight in the refractory material. When it is less than 5% by weight, the CO gas generated by the oxidation of the carbon-based raw material reduces the filling degree of C and SiO ₂ in the structure generated by the decomposition of silicon carbide, and the slag resistance and strength decrease. To do. On the other hand, if it exceeds 15% by weight, the amount of SiO ₂ generated becomes excessive, and the slag resistance and strength decrease.

The particle diameters of the carbon material and silicon carbide are not particularly limited and may be appropriately selected. For example, 3000 to 500μ is about 90% and 210μ or less, and 74μ or less is about 70%. Good.

Carbon black is effective in improving the plasticity, bondability and slag resistance of the occluding material. The carbon black is not particularly limited and any ordinary one can work, and examples thereof include a channel black, a furnace black and an acetylene black produced by incompletely burning hydrocarbons. When using carbon black, it is desirable that the water content is 0.5% or less and the carbon content is 97% or more. If the water content exceeds 0.5%, a large amount of H ₂ and CO will be generated due to the rapid temperature rise during the use of the occluding material, and the pressure inside the occluding material momentarily becomes high, causing cracks, pores, etc. Is reduced. Further, if the carbon content is less than 97%, COOH groups and the like remain to some extent, which decompose during the temperature rising period when the plugging material is used, and reduce the strength. The particle size of the carbon black is not particularly limited and can be appropriately selected, but it is preferable to use, for example, an average particle size of 74 μ or less. If it exceeds 74μ, the cohesive force is lowered, and the plasticity suitable for filling the taphole may not be obtained.

The blending amount of carbon black is preferably 4 to 15% by weight in the raw material of the occluding material. If it is less than 4% by weight, the characteristics of carbon black will not be fully exhibited, while if it exceeds 15% by weight,
The plasticity becomes too large, making it difficult to fill the taphole.

Metallic silicon reacts with CO gas generated by oxidation of a carbon-based raw material to generate silicon carbide (3Si + 2CO → 2β-SiC + Si
O ₂ ), exerts a strong bonding force mainly in the temperature range of about 1100 to 1500 ° C., and improves strength and slag resistance. The SiO ₂ liberated during the formation of silicon carbide suppresses the excessive generation of CO gas and maintains the compactness of the structure for a long time.

The content of metallic silicon is preferably 2 to 8% by weight in the raw material of the plugging material. If it is less than 2% by weight, the above effect is not exhibited. On the other hand, if it exceeds 8% by weight, the strength becomes excessive and it becomes difficult to open the taphole.

The Al ₂ O ₃ —SiO ₂ -based refractory aggregate is effective in improving the slag resistance and suppressing the fire resistance of the plugging material component, mainly in the high temperature range of 1500 ° C. or higher. The Al ₂ O ₃ -SiO ₂ refractory aggregate is not particularly limited, and any ordinary one can be used, for example, Al ₂ O ₃ content of 10 to 20%, SiO ₂ content of 75 to 85% , Al ₂
Those having an O ₃ content of 85 to 95% and a SiO ₂ content of 5 to 10% are particularly preferable.

The compounding amount of Al ₂ O ₃ —SiO ₂ -based refractory aggregate is 5 to 2 in the plugging material.
It is good to set it to 0% by weight. If it is less than 5% by weight, there is no effect in suppressing the oxidation of the occluding material in the high temperature region, while if it exceeds 20% by weight, the slag resistance is lowered.

In the present invention, a liquid organic binder such as coal tar, resole type or novolak type phenol resin is used as the binder. The blending amount of the liquid organic binder is preferably about 15 to 26 parts by weight with respect to 100 parts by weight of the plugging material. If it is less than 15 parts by weight, the raw materials of the plugging material are not uniformly mixed, so that sufficient plasticity cannot be obtained, and furthermore, each raw material cannot exhibit its characteristics. If it exceeds 26 parts by weight, the organic binder contains volatile components, so the amount of volatile components increases, and cracks, pores, etc. occur in the occlusive material structure during the temperature rise period after plugging of the taphole. However, the strength is reduced.

The occlusive material of the present invention can be produced by kneading a predetermined amount of each of the above raw materials.

Effects of the Invention The blast furnace taphole closing material of the present invention has excellent slag resistance, heat resistance, wear resistance and strength with respect to iron and slag, so that the tapping time can be extended to increase the number of tapping times. The workability can be reduced and the workability can be significantly improved.

Examples The following examples and comparative examples will further clarify the present invention. Tables 1 to 3 show the chemical components and the like of the raw materials used in the examples.

Examples 1 to 3 and Comparative Examples 1 to 4 Coal tar was added to 100 parts by weight of the occluding material as a mixing ratio shown in Table 4 and kneaded well, and the occluding material of the present invention (Examples 1 to 3) and conventional The occluding material (Comparative Examples 1 to 4) was manufactured. Each of the obtained plugging materials was molded, then fired at 1400 ° C., and then subjected to a performance test. The results are shown in Table 4.

From Table 4, it can be seen that the product of the present invention has significantly superior slag resistance and strength as compared with the conventional product.

When the product of the present invention (Example 3) and the conventional product (Comparative Example 2) were used to block the tap hole of the large blast furnace of Company A (4500 m ³ ), the average tap time of the conventional product was 190 minutes. On the other hand, the product of the present invention was 210 minutes and could be used longer than the conventional product. Also, the number of tapping was reduced from 8 times / day to 7 times / day, and the workability was improved.

Claims (1)

[Claims] (A) 60 to 84% by weight of carbon material, 5 silicon carbide
~ 15 wt%, carbon black 4-15 wt%, metallic silicon 2-8 wt% and Al ₂ O ₃ -SiO ₂ based refractory aggregate 5-20 wt%
A blast furnace taphole plugging material containing 100 parts by weight of a plugging material as a raw material and (b) 15 to 26 parts by weight of a liquid organic binder.