JP2008105889A - Taphole stopper - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a taphole stopper having high adhesivity and improved wear resistance and corrosion resistance and useful for the protection of a furnace wall with the improved adhesive strength to an existing material. <P>SOLUTION: The taphole stopper is obtained by mixing and kneading anhydrous coal tar and powdery pitch in a refractory material and the ratio of total fixed carbon in the anhydrous coal tar and the powdery pitch is controlled to 40-50 mass%. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a tap hole closing material, and more particularly, to a tap hole closing material used for filling and closing a tap hole of a blast furnace and an electric furnace.

  Each current blast furnace is equipped with 1 to 4 outlets in one furnace, and the normal outlet operation is performed by alternately using these outlets, and the opening and closing intervals of the outlets are the same. Although it is usually spent several hours at the tap, in recent years the blast furnace has been increased in size and increased in high-pressure operation, the coke ratio has been greatly reduced by injecting pulverized coal, etc., and the operating years have been significantly extended. Among these, the required quality for the tap hole closing material has become increasingly severe.

  The techniques required for the filling hole closing material generally include good filling by a press-fitting machine, strong bonding strength at high temperatures, and excellent hot metal resistance. On the other hand, it plays an important role of protecting the furnace bottom and increasing the durability of the blast furnace by the accumulation of the plugging material to be filled.

  The tap hole plugging material is usually a combination of a fire-resistant raw material containing clay and a sintering aid such as metal with a coal-based binder or a resin binder (Patent Documents 1 to 3), and a petroleum-based binder. (Patent Document 4, Patent Document 5) are generally known, and in particular, in the tap hole closing material in Patent Document 1 and Patent Document 2, the wear resistance against hot metal and slag and Insufficient corrosion resistance.

In order to solve this problem, the present applicant has previously proposed a tap hole plugging material obtained by adding powdered coal pitch having a softening point of 250 ° C. or higher to anhydrous coal tar (Patent Document 3). The powdery coal pitch with a softening point of 250 ° C. or higher in the tap hole plugging material has less volatile content, the fixed carbon remains at a higher rate than before, and the carbon bond in the plugging material can be strengthened, resulting in a denser powder. However, there is a demand for improved adhesion, strength, and durability.
JP 57-7875 A JP-A-3-279271 JP 11-278949 A JP 51-115513 A JP-A-51-61515

  The present invention provides an exit hole closing material useful for protecting a furnace wall by improving adhesive strength with an old material while having high adhesiveness as an exit hole closing material and improving the wear resistance and corrosion resistance. Let it be an issue.

  The brewing hole blocking material of the present invention is a brewing hole blocking material prepared by mixing and kneading anhydrous coal tar and powdered pitch with a refractory material, and the total fixed carbon ratio in the anhydrous coal tar and powdered pitch. The amount is 40% by mass to 50% by mass.

  The fixed carbon ratio in anhydrous coal tar is 32% by mass to 36% by mass, and the fixed carbon ratio in powdery pitch is 85% by mass to 93% by mass.

  The refractory material is characterized in that anhydrous coal tar and powdery pitch are blended at a ratio of 10% by mass to 30% by mass.

  The tap hole closing material of the present invention comprises a refractory raw material, anhydrous coal tar, and pitch. The binder in the present invention consists of anhydrous coal tar and pitch, but in order to solve the problems in the present invention, the present inventors need to reinforce the organic binder in the tap hole closing material. Focused on reducing the volatile components as much as possible and increasing the fixed carbon rate. First, it is considered effective to use anhydrous coal tar with a high fixed carbon ratio. However, anhydrous coal tar with a fixed carbon ratio exceeding 36% by mass is highly viscous and difficult to transport, and is easy to handle when used. bad. Therefore, anhydrous coal tar having a fixed carbon ratio of 32% by mass to 36% by mass is preferable from the viewpoint of filling workability and mud gun ability as the tap hole closing material. Examples of commercially available products include high-viscosity products (viscosity 1,000 cps / 60 ° C., fixed carbon ratio 35 mass%). The coal tar is anhydrous coal tar having a water content of 0.5% by mass or less. The amount of anhydrous coal tar added is adjusted based on filling workability and mud gun capability.

  Moreover, even if it exists in a pitch, it is good to raise the fixed carbon rate as a whole, and to raise the fixed carbon rate as the whole organic binder. Pitch has the same origin as tar, and pitch is easily dissolved in tar and has similar characteristics in terms of characteristics. As the pitch, a powder pitch having a fixed carbon ratio of 85 mass% to 93 mass% may be used. Examples of the powdery coal pitch include those having a softening point of 350 ° C. and fixed carbon of 90% by mass.

  The anhydrous coal tar and the powdery pitch may be added together in an amount of 10% to 30% by mass, preferably 16% to 30% by mass, as an outer coating with respect to the refractory material. Anhydrous coal tar may be added to the refractory material as an outer coating at 15% by mass to 20% by mass, and powdery pitch may be added to the refractory material as an outer coating at a rate of 1% by mass to 10% by mass.

  Moreover, it is good for the fixed carbon rate in the sum total of anhydrous coal tar and powder pitch to be 40 mass%-50 mass%. Thereby, a carbon bond is strengthened and the characteristic as a tap hole closing material can be improved. If the total fixed carbon ratio is less than 40% by mass, there is no significant difference from carbon bonding with anhydrous coal tar alone, and if it exceeds 50% by mass, the viscosity becomes high and kneading becomes difficult, which causes problems in production and work. Is not preferable.

  In the refractory aggregate in the tap hole closing material, strength development is not recognized at a low temperature of 1000 ° C. or less, and it largely depends on carbon bonding by an organic binder at a low temperature of 1000 ° C. or less. The brewing hole plugging material of the present invention has a fixed carbon ratio of 40% by mass or more in the organic binder, the carbon bond is strengthened, and the brewing hole plugging material in a low temperature region of 1000 ° C. or less. The durability of can be improved.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.
(Example 1)
The blended raw materials shown in Table 1 below were kneaded at the blending ratio (mass%) for about 5 minutes, and anhydrous coal tar heated to 60 ° C. was added thereto, and kneaded for about 1 hour.

The amount of anhydrous coal tar added in each Example and each Comparative Example is an amount adjusted so that the total load becomes about 350 kgf by the extrusion resistance measuring device (Marshall test) shown in FIGS. That is, the kneaded clay kept at 60 ° C. is filled into a stainless steel sample holder (L ₁ = 9 cm, L ₂ = 6 cm, L ₃ = 26 cm, L ₄ = 12 cm, L ₅ = 2 cm) as shown in FIG. 2 using the measuring apparatus shown in FIG. 2 (A is a sample extrusion faceplate, B is a sample holder, C is a pedestal, and D is a cylinder head), and the extrusion speed of the cylinder head D is 10 mm / sec. The resistance is measured as a total load applied to the sample extrusion faceplate A. As described above, the amount of anhydrous coal tar added in the kneaded clay is adjusted so that the total load is about 350 kgf.

  The adhesive strength was measured with a three-point bending strength measuring apparatus (according to JIS R2213) shown in FIG. That is, two firing samples (4 cm × 4 cm × 8 cm) of the tap hole closing material fired at 1500 ° C. are prepared and bonded as shown in FIG. Reduction baking is performed at 800 ° C., and the adhesive strength (MPa) is measured.

  Table 1 below shows the measurement results of the adhesive strength (MPa) of the tap hole closing material obtained in each example and each comparative example.

  In the table, coal pitch and coal tar indicate the amount of outer coating (% by mass).

Coal pitch A is softening point 110 ° C., fixed carbon 60% by mass, ash content less than 0.5% by mass Coal pitch B is softening point 350 ° C., fixed carbon 90% by mass, ash content less than 0.5% by mass High viscosity product (35% by mass of fixed carbon, 0.1 to 0.3% by mass of moisture, 1,000 cps / 60 ° C.)
Coal tar B is a low-viscosity product (fixed carbon 28% by mass, moisture 0.1-0.3% by mass, 200 cps / 60 ° C.).

  In Example 1, a fixed carbon 35 mass% anhydrous tar A (high viscosity product 1,000 cps / 60 ° C.) was added with a fixed carbon 90 mass% pitch B, and the total fixed carbon ratio of tar and pitch was 43 mass%. It is the tap hole closing material adjusted so that it becomes. The bond strength was clearly increased to 2.0 MPa.

  In Example 2, the pitch was increased and the total fixed carbon ratio was 49% by mass, and the adhesive strength further increased to 2.2 MPa. Although not shown in the table, when the total fixed carbon ratio was further increased to 51% by mass, the viscosity became too high and kneading became difficult, resulting in inconvenience in production.

  In Comparative Example 1, only coal tar B having a fixed carbon ratio of 28% by mass was used as the binder, the fixed carbon ratio in the binder was 28% by mass, and the adhesive strength was 0.3 MPa.

  Comparative Example 2 is a case where only coal tar A having a fixed carbon ratio of 35% by mass is used as the binder, and the fixed carbon ratio in the binder is 35% by mass. The adhesive strength was 0.5 MPa, which was less than 1/4 of that of the example, although the adhesiveness was improved as compared with Comparative Example 1. Anhydrous coal tar A has a high viscosity of 1,000 cps at 60 ° C., but it is the upper limit within the range where there is no problem in production.

  In Comparative Example 3, pitch B of fixed carbon 90% was added to tar B of fixed carbon 28% by mass to make the total fixed carbon ratio 37% by mass, but the adhesive strength was 0.9 MPa. The intensity was less than half.

  In Comparative Example 4, pitch A of fixed carbon 60% by mass was added to tar A of fixed carbon 35% by mass, and the total fixed carbon ratio was 39% by mass, but the adhesive strength was 1.3 MPa, Although the strength was 70% or less of the example, pitch A with fixed carbon of 60% by mass has a low softening point, melts during kneading, is strong, and easily adheres to each part of the mixer. Was judged unsuitable for production.

It is a figure for demonstrating the shape of the stainless steel sample holder used in order to measure the extrusion resistance pressure of a tap hole obstruction | occlusion material. It is a figure for demonstrating the measuring apparatus used in order to measure the extrusion resistance pressure of a sprue hole obstruction | occlusion material. It is a figure for demonstrating the adhesive strength measuring method of a tap hole obstruction | occlusion material.

Explanation of symbols

  A is a sample extrusion faceplate, B is a sample holder, C is a pedestal, and D is a cylinder head.

Claims (3)

In a tap hole closing material obtained by blending and kneading anhydrous coal tar and powdery pitch with a refractory material, the total amount of fixed carbon ratio in the anhydrous coal tar and powdery pitch is 40% by mass to 50% by mass. A sprue hole closing material characterized by the above. 2. The tap hole closing material according to claim 1, wherein the fixed carbon ratio in anhydrous coal tar is 32 mass% to 36 mass%, and the fixed carbon ratio in the powdery pitch is 85 mass% to 93 mass%. 2. The tap hole closing material according to claim 1, wherein anhydrous coal tar and powdery pitch are blended in an amount of 10% by mass to 30% by mass with respect to the refractory material.

Images