JPH0532344B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a lining material for hot metal and molten steel processing vessels, and particularly to a carbon-containing refractory that suppresses the temperature drop of hot metal and molten steel. [Prior Art] Rouseite, clay, high alumina, and zircon refractories have traditionally been used as lining materials for processing containers for hot metal and molten steel to provide stable container life. In recent years, with the trend toward high-grade steel or energy saving, so-called hot metal pretreatment, which involves desiliconization, dephosphorization, and desulfurization, has been carried out.As a result, a large amount of CaO-based flux is added to the hot metal or molten steel, resulting in the formation of slag. Penetration and chemical erosion have increased, and the durability of the above-mentioned refractories has been significantly reduced. Therefore, Al ₂ O ₃ -SiC-C bricks or MgO- which are difficult to get wet with slag and have excellent heat spalling resistance
Graphite-containing refractories such as C bricks have come into use, and as a result their durability has improved considerably. However, the above graphite refractories have a high thermal conductivity, and when used as a lining material, they have the drawback of lowering the temperature of hot metal and molten steel and causing damage to the iron skin. [Problems to be Solved by the Invention] For this reason, Japanese Patent Application Laid-Open No. 1983-1999 was proposed as a method for solving the above-mentioned drawbacks while retaining the advantages of graphite-containing bricks.
As seen in Publication No. 117813, insulation material was inserted between the back of the brick and the iron shell, and
As in Publication No. 41777, a two-layer structure of bricks has been proposed in which graphite-containing bricks are laminated on the operating side and bricks with low thermal conductivity without added graphite are laminated on the back side. However, in the case of the former, when the back side is insulated during use, the temperature of the brick increases more than necessary, which can lead to premature melting and loss. Regarding the latter, a problem has arisen in that when the graphite-containing brick is eroded during use, the graphite-free brick is exposed, and the erosion increases rapidly, impeding stable operation of the processing vessel. [Means for Solving the Problems] The present inventors have proposed a method that suppresses the temperature drop of hot metal, has low thermal conductivity that can prevent shell deformation, and is resistant to slag penetration, such as graphite-containing bricks. As a result of various studies on refractories with excellent heat and spall resistance, the present invention was completed. That is, the present invention provides a carbon-containing refractory comprising 3 to 20% by weight of amorphous carbon, the balance being at least one of silica, silica, kyanite, and andalusite, a high alumina raw material, silicon carbide, and an organic binder. It is. [Function] Amorphous carbon raw materials such as pitch coke and petroleum coke have traditionally been used as carbon raw materials for unfired carbon-containing bricks, along with graphite raw materials such as scaly graphite, but amorphous carbon has the characteristic of shrinking when heat treated. As shown in FIG. 1, when it is added to a high alumina raw material to make a brick, the line change after heating and cooling, so-called residual line change rate, becomes negative. When lined with these bricks, the shrinkage of the bricks causes the joints to open and slag ingots enter the joints, causing joint melting and damage, which shortens the life of the furnace, so it is not generally used. The present invention controls the rate of residual linear change by combining silica, rouseki, kyanite, and andalusite with amorphous carbon in an optimal range, thereby obtaining a refractory with excellent volume stability and significantly reduced thermal conductivity. That is. Examples of the amorphous carbon used in the present invention include pitch coke obtained by thermally decomposing coal pitch, petroleum coke produced from vacuum residue during petroleum refining, and carbon black anthracite. The amorphous carbon has a particle size of 0.1 mm or less and is composed of solid carbon.
85% or more is desirable. The reason for this is that pitch coke and petroleum coke have high porosity, and when used as coarse particles of 0.1 mm or more, the porosity of bricks increases and the mechanical strength decreases. In addition, if the solid carbon content is less than 85%, the volatile content is large and the volatile content disappears during use, leading to an increase in porosity and a decrease in strength. The reason why the amorphous carbon is limited to 3 to 20% by weight is that if it is less than 3% by weight, the effect of preventing slag penetration cannot be obtained, and if it exceeds 20% by weight, the mechanical strength of the brick will decrease and the abrasion resistance will be low. This is to become. The reason for blending at least one of silica, Rouseki, kyanite, and andalusite is to utilize the thermal expansion characteristics of these raw materials, that is, the large residual expansion, and to suppress the residual shrinkage of the amorphous carbon-containing brick. As shown in FIG. 2, it varies depending on the raw materials added, but by adjusting the amount added, an appropriate residual expansion property can be imparted and joint opening of the lining brick can be suppressed. High alumina raw materials for aggregate include fused alumina, sintered alumina, bauxite, shale,
Sillimanite, synthetic mullite, siyamoto, etc. can be used. Suitable organic binders to be added include novolac type and/or resol type phenolic resins, furan resins, tarpitch, and the like. Silicon carbide is used as an oxidation inhibitor for amorphous carbon, and is preferably 1 to 15% by weight. If it is less than 1%, no antioxidant effect can be obtained, and if it is more than 15% by weight, corrosion resistance against hot metal and molten steel will decrease. . In addition, metal Al, metal Si powder, glass powder, etc. can be used in combination with the silicon carbide as an antioxidant. [Example] Examples will be described below. After mixing and kneading the inventive product, the comparative product, and the conventional product at the compounding ratios shown in Table 1, they were molded into a regular shape using a friction press. After that, test specimen No. 1 was passed through a drying oven at 200℃ for 20 hours.
-10 were prepared and their physical properties were measured using conventional methods. As a result, as is clear from Table 1, the thermal conductivity of the product of the present invention is significantly lower than that of the conventional product with the addition of scaly graphite, and the corrosion resistance is also 7 to 15.
% improved.

【table】

〔Effect of the invention〕

When specimen No. 1 of the invention product was lined in the hot metal area of a pig iron mixing car, the hot metal temperature decreased and the iron skin temperature was reduced to 1/2 compared to the conventional product No. 10 containing scaly graphite, resulting in a long service life. The performance improved by about 10%. The industrial benefits of achieving both lower molten metal temperature, higher durability, and prevention of damage caused by higher skin temperature are significant.

[Brief explanation of the drawing]

Figure 1 shows bricks with silicon carbide constant at 7% by weight and varying amounts of bauxite and pitch coke.
Figure 2 shows the residual linear change rate after heat treatment in a coke breeze at 1500°C for 3 hours. Silicon carbide is kept constant at 7% by weight, pitch coke is kept at 10% by weight, and kyanite, Rouseki, silica and FIG. 3 is a diagram showing the residual linear change rate after heat treating bricks with varying amounts of andalusite added (the remainder of the aggregate being bauxite) at 1500° C. for 3 hours in a coke breeze.

Claims (1)

[Claims] 1 3 to 20% by weight of amorphous carbon, the balance being silica,
A carbon-containing refractory comprising at least one of Rouseki, Kyanite, and Andalusite, a high alumina raw material, silicon carbide, and an organic binder.