JP3613435B2 - Closure material for molten metal outlet - Google Patents

Description

【００２１】
上記で使用した粉末状の石炭ピッチの性状を下記の表２に示す。
【００２２】
【表２】

【００２３】
表１からわかるように、本発明品は、従来品に比較して、低温側から高温側までの強度が大幅に向上するとともに、組織が緻密化し耐食性を向上することがわかる。その結果、実炉において出銑時間が延長できるとともに、開孔難発生率も低下することができる。
【００２４】
【発明の効果】
本発明の溶融金属出湯口用閉塞材は、低温側と高温側の強度差が小さく、耐摩耗性および耐食性が向上することにより、開孔時の開孔難が少なく、出銑時間を長時間にでき、高炉出銑口用、電気炉出湯口用閉塞材として有用である。[0001]
[Industrial application fields]
The present invention relates to a plug for a molten metal outlet, and more particularly to a plug for a molten metal outlet used in a reducing atmosphere, such as a plug for a blast furnace outlet and an electric furnace outlet.
[0002]
[Prior art]
Conventionally, the plugging material for the molten metal outlet has one or more of rholite, chamotte, and alumina as main raw materials, and silicon carbide, carbonaceous raw materials, silicon nitride iron, etc. and clay are added, and further as a binder. As a binder to be used, anhydrous coal tar has been added and a kneaded material has been generally used.
[0003]
As disclosed in JP-A-57-7875, JP-A-3-279271, JP-A-51-61515, JP-A-51-115513, etc., In some cases, a powdery coal pitch having a softening point of 130 ° C. or lower or a petroleum pitch having a softening point of 230 ° C. or lower is used.
[0004]
However, sufficient strength and corrosion resistance to obtain wear resistance against hot metal and slag are important in order to achieve long-time slagging. However, conventional plugging materials such as those described above are resistant to hot metal and slag. Abrasion and corrosion resistance were insufficient.
[0005]
Japanese Patent Publication No. 57-23675 discloses that a silicon alloy is added to improve the high temperature strength and improve the durability, but it cannot be said that this plugging material is sufficiently improved in the low temperature strength. Insufficient wear resistance, and there is a large difference in strength between the high temperature side and the low temperature side, and there is a problem that cracks are easily generated at the time of opening, making it difficult to open.
[0006]
[Problems to be solved by the invention]
The present invention provides a sealing material for a molten metal outlet, which improves wear resistance and corrosion resistance, achieves long-time slagging, and is less likely to be difficult to open due to cracks. Is an issue.
[0007]
[Means for Solving the Problems]
The plug material for the molten metal outlet of the present invention is a powdery coal pitch having a particle size adjusted refractory material of 91 wt% to 64 wt%, anhydrous coal tar as a binder of 35 wt% to 8 wt%, and a softening point of 250 ° C. or higher. It is characterized by being blended and kneaded at a ratio of 1% by weight to 7% by weight.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
The refractory material is generally composed of one or more oxide refractory materials such as rholite, chamotte, alumina, spinel, and magnesia, and a carbonaceous raw material, silicon carbide, silicon nitride-based raw material, and refractory clay. . The refractory material is adjusted to a particle size of 10 mm or less, preferably 5 mm or less, and the blending ratio in the plugging material is 91 wt% to 64 wt%, preferably 90 wt% to 80 wt%.
[0009]
Examples of the refractory clay include Kibushi clay, Sakaime clay, and ball clay, which are added to impart shape retention and slipperiness necessary for filling workability, and are 3% to 20% by weight in the refractory material. %, Preferably 5 to 15% by weight. If it is less than 3% by weight, the filling workability is deteriorated, and if it exceeds 20% by weight, the corrosion resistance is remarkably lowered.
[0010]
Conventional anhydrous coal tar is used as the binder, and purified tar Nos. 1 and 2 are exemplified as commercially available products, which have a water content of 0.5% or less. The amount of the binder added is adjusted based on the filling workability and the mud gun ability, but in the plugging material, the blending ratio is 8% to 35% by weight, preferably 10% to 20% by weight, and the effect is sufficient. .
[0011]
As a powdery coal pitch having a softening point of 250 ° C. or higher used for reinforcing the binder, for example, special pitch MCP-250 (softening point 250 ° C.), MCP-350 (softening point 350 ° C.) of Adchemco Corporation, etc. Is mentioned. The powdery coal pitch may have a softening point of 250 ° C. or higher, but preferably has a softening point of 280 ° C. to 350 ° C. As a compounding quantity, it is good to set it as the ratio of 1 to 13 weight% in an obstruction | occlusion material, Preferably it is 2 to 7 weight%. If the amount is less than 1% by weight, the erosion resistance and the strength improving effect are not sufficient. If the amount exceeds 13% by weight, the total amount of volatile components from the coal pitch increases, making it difficult to obtain a dense structure and the strength improving effect is reduced. Therefore, it is not preferable.
[0012]
The molten metal outlet closure material of the present invention is obtained by adding a powdery coal pitch having a softening point of 250 ° C. or higher as a reinforcing agent for a binder, using a conventional anhydrous coal tar as a binder. In the process of firing at the furnace temperature around the tap, the volatile matter is about ½ compared to the conventional powdery coal pitch with a softening point of 130 ° C or lower and petroleum pitch with a softening point of 230 ° C or lower. Therefore, fixed carbon higher than in the past remains, and the carbon bond in the plugging material can be strengthened, and a denser structure can be formed.
[0013]
As a result, the strength of the plugging material from the low temperature side to the high temperature side can be improved, so that the wear resistance against hot metal and slag is greatly improved, and the amount of carbon uniformly distributed in the structure of the plugging material is reduced. It can be increased and densified, the corrosion resistance is improved, and the brewing can be performed for a long time. In addition, since the strength on the low temperature side can be improved, the difference in strength between the high temperature side and the low temperature side is small, and cracking is difficult to occur at the time of opening, making it difficult to generate difficulty in opening.
[0014]
【Example】
Hereinafter, the present invention will be described in detail by way of examples.
[0015]
Example 1
The formulation of Example 1 shown in Table 1 below was kneaded with a 50 ° C. mixer to obtain a product of the present invention. Instead of the powdered coal pitch A in the blending of Example 1, a conventional powdered coal pitch K was blended and similarly kneaded with a mixer at 50 ° C. to obtain Comparative Example 1.
[0016]
(Example 2)
The formulation of Example 2 in Table 1 below was kneaded with a mixer at 50 ° C. to obtain the product of the present invention. Instead of powdered coal pitch B in Example 2 and blending, conventional powdered petroleum pitch N was blended and similarly kneaded with a mixer at 50 ° C. to obtain Comparative Example 2.
[0017]
The blocking materials of Examples 1 and 2 and Comparative Examples 1 and 2 were molded into 40 × 40 × 160 mm blocks at a molding pressure of 4.9 MPa to form specimens, each at 800 ° C. and 1500 ° C. for 3 hours. After reducing firing, the bending strength (MPa) and the apparent porosity (%) were measured.
[0018]
In addition, as a corrosion resistance test, the specimen reduced and fired at 800 ° C. for 3 hours was used, and by a rotating arc furnace erosion test method, pig iron + slag was used as an erodant, and 1550 ° C. for 10 hours in a reducing atmosphere. An erosion test was performed. And the sample was cut | disconnected after completion | finish of an erosion test, and the erosion dimension was measured. The erosion index was expressed as an index when the erosion dimension of the plug for the molten metal outlet obtained in Comparative Example 1 was 100.
[0019]
The average tapping time and the difficulty of opening the holes when the plugging materials of Examples 1 and 2 and Comparative Examples 1 and 2 were used as the plugging material for the actual blast furnace outlet were used as the actual furnace usage results.
Table 1 below shows the composition of the plugging materials and the measurement results of Examples 1 and 2 and Comparative Examples 1 and 2.
[0020]
[Table 1]

[0021]
The properties of the powdery coal pitch used above are shown in Table 2 below.
[0022]
[Table 2]

[0023]
As can be seen from Table 1, the product of the present invention has a significantly improved strength from the low temperature side to the high temperature side and a dense structure and improved corrosion resistance as compared with the conventional product. As a result, the tapping time can be extended in an actual furnace, and the rate of difficulty in opening holes can be reduced.
[0024]
【The invention's effect】
The closure material for the molten metal tap of the present invention has a small difference in strength between the low temperature side and the high temperature side, and has improved wear resistance and corrosion resistance. It is useful as a plugging material for blast furnace outlets and electric furnace outlets.

Claims (1)

91% to 64% by weight of refractory material with adjusted particle size, 35% to 8% by weight of anhydrous coal tar as a binder, and 1% to 7% by weight of powdered coal pitch with a softening point of 250 ° C. or higher. A closing material for a molten metal tap, characterized by being kneaded.