JPS6256354A - Graphite-containing refractory brick - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] 1 Izumi Norigidan ■Kou 1 The present invention relates to a graphite-containing refractory brick.

Recently, from the viewpoint of upgrading steel and saving energy, preliminary treatment of hot metal to remove silicon, phosphorus, and Wt has been carried out. Mill scale, iron ore, iron sand), soda ash (Na2 GO3>, limestone (CaCO3), quicklime (Cab), fluorite (CaF2)
> etc. are used as processing agents. However, while the above treatment agents are excellent refining agents, they also act as powerful corrosive agents for refractories.

Alumina (A9203>) and spinel (MqO・
AQ 203>, magnesia, etc. are known. However, although these refractory materials have excellent corrosion resistance, they have the disadvantage that they have poor thermal spall resistance or structural spall resistance, and are susceptible to damage due to cracking and flaking under usage conditions with large temperature changes. There is. For example, alumina has a high linear expansion coefficient of 0.86% at 1000°C, and its melting point is over 2000°C, so it does not form a liquid phase at the operating temperature. Under similar operating conditions, CabSS t
Slag components such as 02 and Feo penetrate and easily cause structural spalls. Similarly to alumina, spinel and magnesia are inferior in heat spall resistance and structural spall resistance due to slag penetration, and the inherent excellent properties of these materials cannot be utilized. Therefore, in order to suppress damage caused by such thermal spalls and structural spalls,
These fire-resistant materials are mixed with graphite and the like.

However, such refractory bricks containing graphite have poor oxidation resistance because graphite is easily oxidized, and also have poor durability because the graphite may dissolve into the steel and disappear when the refractory bricks are used. It is also insufficient in this respect. Therefore, various methods have been proposed to impart excellent oxidation resistance and durability to graphite-containing refractory bricks. Examples of such methods include (1) vacuum-pressing graphite-containing refractory bricks to make the brick structure dense; (2) fine powders of silicon, aluminum, and their alloys, and carbides such as silicon carbide. A method of adding a small amount to graphite-containing refractory bricks,
(3) A method of adding a small amount of inorganic low-melting point glass components such as borosilicate glass and phosphate glass to graphite-containing refractory bricks, (4)
) Methods of applying various antioxidants to the surface of graphite-containing refractory bricks are known. All of these methods aim to suppress wear due to oxidation by minimizing the chances of contact between graphite and oxygen (including Co and CO2) during the production or use of graphite-containing refractory bricks. . However, although all of these methods have been practically applied and achieved considerable results, they are still not fully satisfactory.

B. Means for Solving the Problems The inventor of the present invention, in response to the current situation, has conducted extensive research to develop graphite-containing refractory bricks that have excellent oxidation resistance, durability, etc., and has developed the following specific graphite-containing refractory bricks. By using the above (
It has been discovered that graphite-containing refractory bricks having excellent oxidation resistance, durability, etc. can be obtained without performing the special treatments described in 1) to (4). The present invention was completed based on this knowledge.

That is, in the present invention, the particle size is 74 μm or less, and 50% by weight or more of the particles have a particle size of 20. The present invention relates to a graphite-containing refractory brick characterized by containing 3 to 40% by weight of graphite having a particle diameter of less than czm.

As the graphite used in the present invention, a wide variety of conventionally known graphites can be used, such as naturally occurring graphite such as scale graphite, chip graphite, and earthy graphite, quiche graphite, coal pitch coke, and petroleum pitch coke (needle coke). , carbon black, etc. Among these, scaly graphite, chip graphite and earthy graphite are preferred, and chip graphite is most preferred. In the present invention, it is essential to use graphite having a particle size of 74 μm or less, of which 51ff1% or more has a particle size of 20 μm or less.

Here, the grain size refers to the spread of the layer planes of graphite crystals (a-axis and b-axis).
It means the size in the axial direction.

When the graphite particle size is 74 μm or more, and even if the graphite particle size is 74 μm or less, less than 50% by weight of the graphite particle size is 20 μm or less, the homogeneity of the structure of the refractory brick obtained It is unsuitable because it deteriorates filling properties and hot strength, and also reduces oxidation resistance, corrosion resistance, etc. The purity of graphite used in the present invention is not particularly limited, and is usually 80 to 98%.
A moderate amount is sufficient.

In the present invention, the above-mentioned specific graphite is preferably blended into the refractory brick of the present invention in an amount of 3 to 40% by weight. If the above-mentioned specific graphite is used, the distribution of graphite in the brick structure becomes homogeneous, and as a result, the graphite with a diameter of, for example, 1mm becomes homogeneous.
The desired effect can be achieved by adding a smaller amount of (b) than when using the following graphite. When the blending amount of graphite exceeds 40wt%, the amount of oxidation loss of graphite increases, and the brick structure deteriorates due to oxidation loss of graphite, resulting in the loss of 1% of the brick.
(It is not preferable because the amount of graphite increases. Also, if the blending amount of graphite is less than 3% by weight, it is preferable because the heat spall resistance, structural spall resistance, etc. of 17 fire resistance/ν decreases.) In the present invention, it is particularly preferable to blend the above-mentioned specific graphite in the refractory brick of the present invention so as to contain 5 to 20% by mass.

As the refractory material used in the present invention, conventional refractory materials such as alumina, spinel, magnesia, silica, silicon carbide, and silicon nitride can be used as they are or after adjusting the particle size as appropriate. Further, powders of aluminum, silicon, etc., and powders of alloys thereof can also be used.

When manufacturing the graphite-containing refractory/vga of the present invention,
Any method conventionally used to produce this type of refractory brick can be used, such as adding a binder such as a phenolic resin to the graphite and refractory material, kneading the mixture, drying it after molding, or further It can be manufactured by firing.

The graphite-containing refractory brick of the present invention has high strength, excellent corrosion resistance, oxidation resistance, durability, etc., and is suitable for practical use. Moreover, if deep graphite is used in particular among graphites, it is possible to obtain refractory bricks with further improved corrosion resistance and F14 abrasion resistance.

X-Toyoichi 1 Examples and comparative examples are given below to further clarify the present invention.

Example 1 Using various graphites shown in Table 1 below, AQ203 SICG-based samples were prepared at the blending ratios shown in Table 2 below. In Table 1, the graphites satisfying the conditions of the present invention are C, D,
F and H.

The sample was prepared as follows. After mixing the refractory material and graphite for 10 minutes, add phenolic resin as a binder, knead for 20 minutes, and use a hydraulic press to form a 114 mm x 114 m sheet at a pressure of 1150 ka/cm2.
It was molded into a shape of m x 65 mm.

Thereafter, it was dried at 220° C. for 24 hours to prepare a test sample. These samples were subjected to various tests shown in Table 3, and the results are also shown in Table 3.

Table 1 Graphite A: Made in Madagascar, trade name AGM/C (Shanetsu graphite ■), flaky graphite B: Made in China, trade name P85T (Tozai ■), flaky black, 641C: Made in China, trade name 285 [ Tozai■], scaly graphite D: made in China, product name #1000 (tozai■), scaly graphite E: made in the Republic of Korea, product name C@ [Hikari Casting Materials Works],
Powdered graphite F: pulverized graphite E above Graphite G: Made in Sri Lanka, product name FineChips
BF9597 [ITOCHU Corporation ■], massive graphite E-1 = produced in Sri Lanka, product name Ultra Fin
e Powder (Itochu Corporation ■), lumpy Table 2 (Product name PR-50273, manufactured by Sumitomo Durez) Table 3 shows that the particle size of graphite is 74 μm or less, and that more than 50% of the back of the particle is made up of particles. It is clear that when graphite with a diameter of 20 μm or less is used, it has good filling properties, low porosity, high hot strength, and excellent oxidative wear resistance and corrosion resistance.

Example 2 Samples were prepared with the blending ratios shown in Table 4 below and tested. The sample preparation method and testing method were the same as in Example 1. The test results are also listed in Table 4.

From Table 4, it is clear that excellent graphite-containing refractory bricks can be obtained by using fine graphite even in spinel-carbon and magnesia-carbon refractories.

Table 4 (Product name PR-50273, manufactured by Sumitomo Durez Co., Ltd.) Example 3 Graphite-containing refractory bricks were manufactured at the ratio of the present invention product 5, the present invention product 8, and the comparative amount 5 in Table 4, and the slag from a mixed iron car was A practical test was conducted in the line section.

After using the bricks 212 times, we collected the bricks and measured the amount of wear, and found that the product 5 of the present invention lost 0.16 m1T per charge.
The amount of loss of l, the invention product 8 is 0.12 mm per charge.
On the other hand, comparative product 5 has a loss of 0.2 per jersey.
It was a failure with 1mm of wear.

(that's all)

Claims (1)

[Claims] (1) A graphite-containing refractory brick characterized by containing 3 to 40% by weight of graphite having a particle size of 74 μm or less, of which 50% by weight or more has a particle size of 20 μm or less.