JPS62197360A - Refractories for lining - 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 Field of Industrial Application The present invention relates to a refractory for lining, and more specifically, an AQ20s-8i of a pig iron mixing car or pig iron receiving ladle used for holding and transporting molten metal, refining, etc. This invention relates to a C-C lining refractory.

BACKGROUND OF THE INVENTION Conventionally, A0203 StCC refractories have been used as lining refractories in the hit areas of pig iron mixers or pig iron receivers. However, the above AQ203-8! C-
In C-class refractories, the silicon carbide and carbon components thereof are easily oxidized, and structural spalling is likely to occur due to mechanical or thermal shock during pig iron receiving and contact with slag.

In other words, silicon carbide has high thermal conductivity and is effective in preventing spalling, but it reacts with mill scale used as a desiliconizing agent during the desiliconizing treatment of molten metal, producing 5i02 and CO2.
They emit gas, are rapidly consumed, and their properties deteriorate during use.

In addition, due to its small thermal expansion coefficient and elasticity, Chikarabon can effectively absorb the thermal expansion and contraction of alumina-based and alumina-silica-based aggregates, and reduce iron oxides in the slag to form refractories. It suppresses reactions with other compositions in the refractory, and further prevents slag from penetrating into the refractory due to its property of being difficult to wet. Therefore, although the spalling resistance is improved, oxidation progresses due to the reduction of iron oxide and the reaction with oxygen in the air, which has the disadvantage of weakening the structure of the heavy-duty material. Aluminum is used to effectively exhibit the above-mentioned advantages of carbon in an actual furnace. Aluminum melts at 690℃,
It plays the role of an oxidation inhibitor by reducing Co gas generated by oxidation of carbon to carbon again. However, the addition of aluminum causes volumetric expansion, which causes peeling and cracking, so the amount of aluminum added is limited, and therefore its effectiveness is limited. Refractories containing both silicon carbide and aluminum are also manufactured. (Japanese Patent Publication No. 61-882) However, this refractory is also undesirable because it has the same drawbacks as those of carbon and aluminum.

In view of the above-mentioned problems, the inventor of the present invention has conducted extensive research to develop a refractory with excellent oxidation resistance and spalling resistance, and has obtained the following knowledge and has developed the present invention. completed.

That is, by using a refractory material consisting of refractory aggregate, carbon material, silicon carbide, and lithium phosphate and/or barium phosphate, the present inventor has achieved oxidation resistance and spalling resistance compared to conventional refractories. succeeded in obtaining an excellent refractory.

The present invention uses 55 to 85 parts by weight of fireproof aggregate and 10 to 85 parts of carbon material.
1 to 5 parts by weight of an organic binder are blended to 100 parts by weight of a refractory material consisting of 20 parts by weight, 5 to 20 parts by weight of silicon carbide, and 1 to 5 parts by weight of lithium phosphate and/or barium phosphate. This relates to the characteristic refractory material for lining.

In the refractory of the present invention, one or more selected from high alumina materials and spinel is used as the refractory aggregate. High alumina refers to minerals containing corundum, mullite, and silica, and containing A9203 [165% or more]. Further, spinel refers to a material having an A9203 MQO composition and containing 70% or more of A+1203. The amount of refractory aggregate used is preferably about 55 to 85 parts by weight.

If it is less than 55 parts by weight, it will be difficult to maintain mechanical strength during pig iron receiving. When the amount exceeds 85 parts by weight, durability decreases due to increased spalling and infiltration of slag.

As the carbon material, solid carbon materials with low ash content, such as artificial graphite, scaly graphite, and beaded graphite, are preferable.

These solid carbon materials preferably contain about 95% of particles with a particle size of about 0.6 to 0.151. 0.
When it exceeds 61, the oxidation reaction slows down, but when it comes into contact with the slag, it tends to accelerate the infiltration of the slag into the refractory because it is coarsely dispersed in the structure of the refractory, impairing its durability. 0.15
If it is less than 11, the generation of Co gas due to oxidation will increase at an accelerated pace, the carbon material will be consumed, and the structure may become brittle.

The amount of the solid carbon material used is preferably about 10 to 20 parts by weight. If it exceeds 20 parts by weight, the strength of the refractory will decrease, which is not preferable. In addition, if the amount is less than 10 parts by weight, it will be oxidized by iron oxide as a desiliconizing agent, and the carbon material will be used to prevent slag from penetrating into the refractory structure, and to prevent cracking and peeling due to thermal shock. Effectiveness is significantly reduced and durability is shortened.

Silicon carbide provides the refractory of the present invention with thermal shock resistance and oxidation resistance in a high temperature range. That is, silicon carbide has a small coefficient of thermal expansion and a high thermal conductivity, so it is effective in preventing the occurrence of cracks and peeling due to thermal shock.

Silicon carbide also reacts with Co gas generated by oxidation of carbon and decomposes into carbon and 5fO2, and Stow coats carbon to prevent oxidation.

The amount of silicon carbide used is preferably about 5 to 20ffi 1 part. If it exceeds 20 parts by weight, it reacts with iron oxides in the slag, causing significant wear and tear, which is not preferable. 5
If the amount is less than 1 part by weight, thermal shock resistance decreases.

In the present invention, by using a powdered metal phosphate as an oxidation inhibitor, oxidation of components in the refractory in the gas phase and solid phase is strongly prevented. This also significantly prevents solid phase oxidation, which is a serious drawback of silicon carbide. As the metal phosphate, lithium phosphate and/or barium phosphate, which strongly suppress oxidation phenomena at temperatures of 600 to 1400°C, are used. Sodium salts of metal phosphates other than the above,
Manganese salts, aluminum salts, etc. are not suitable for use because they have low oxidation inhibiting power. Lithium phosphate and barium phosphate used in the present invention adsorb onto the surface of carbon particles to form a coating and produce an oxidation inhibiting effect. It is effective in preventing On the other hand, conventional oxidation inhibitors (aluminum, etc.) only inhibit oxidation through the gas phase by utilizing the equilibrium vapor pressure of the gas phase, and do not have the effect of preventing carbon from turning into a gas phase. You can't expect much.

The amount of lithium phosphate and/or barium phosphate used is
The amount is preferably about 1 to 5 parts by weight.

If it exceeds 5 parts by weight, the hot strength will decrease due to an increase in the glass phase at high temperatures. If it is less than 1 part by weight, the surface of the carbon particles will be insufficiently coated, and the oxidation inhibiting effect will be reduced.

As the organic binder, for example, coal tar, coal tar pitch, resol type and novolak type phenolic resin, furan resin, etc. are used.

The amount of these organic binders used is preferably about 1 to 5 parts by weight per 100 parts by weight of the refractory material. If it exceeds 5 parts by weight, expansion and peeling and cracking will occur due to rapid temperature changes during drying and pig iron receiving, which is undesirable. If it is less than one layer, unevenness will occur during manufacturing and kneading, and cracks will occur during molding and drying.

The refractory of the present invention comprises 100 parts of refractory material consisting of 55 to 851 parts by weight of refractory aggregate, 10 to 20 parts by weight of carbon material, 5 to 20 parts by weight of silicon carbide, and 1 to 5 parts by weight of lithium phosphate and/or barium phosphate. Organic binder 1 to 5 for heavy passage area
It is manufactured by blending parts by weight, kneading, molding, and drying at about 200 to 450°C.

W-ri The refractory of the present invention exhibits the following excellent effects.

(1) In the refractory of the present invention, peeling and cracking that occur in refractories using conventional oxidation inhibitors such as aluminum are not observed.

(2) The refractory of the present invention has excellent oxidation resistance, spalling resistance, etc. compared to conventional products, and therefore has increased durability, improves work efficiency, and reduces equipment investment costs.

EXAMPLES Examples and comparative examples are shown below to make the present invention even clearer.

Examples 1 to 3 Refractory aggregates (high alumina aggregates), silicon carbide, and carbon materials (graphite) having chemical components shown in Tables 1, 2, and 3 were used, and the formulations shown in Table 4 were used. Refractories of the present invention (Examples 1 to 3) were manufactured using the following ratios.

In its production, 0.2 parts by weight of phenolic resin is well kneaded with 15 parts by weight of graphite, and then 2 parts by weight of lithium phosphate (and/or barium phosphate) are added and kneaded further. The mixed material and the remaining raw materials were mixed, molded, and dried.

Comparative Examples 1 and 2 The same raw materials as in the examples were mixed at the mixing ratio shown in Table 4.
A conventional refractory was produced by molding and drying.

A quality characteristic test was conducted on the product of the present invention and the conventional product.

The results are also listed in Table 4.

Table 1 Chemical composition of high alumina aggregate Table 2 Chemical composition of silicon carbide Table 3 Composition of graphite As is clear from Table 4, the refractory of the present invention has remarkable oxidation resistance compared to conventional products. showed improvement. In particular, no decrease in oxidation resistance was observed even when the blended amount of graphite was increased. Furthermore, the compressive strength at room temperature, the hot bending strength, etc. showed considerable improvement, and it can be seen that the bending strength at room temperature was also improved, albeit slightly. The above results show that the refractory of the present invention is superior to conventional products.

The refractory of the present invention manufactured in Example 3 and the conventional product were used for lining the slag line of a slag line of a company A company 280,
As a result of observation and investigation at the end of the 130 charge (silicon removal rate 40%), the degree of wear was 81 when the conventional product was set as 100.
It was confirmed that the durability was extended by about 20% compared to conventional products.

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Claims (1)

[Claims] (1) 55 to 85 parts by weight of fireproof aggregate, 10 to 20 parts by weight of carbon material
It is characterized by blending 1 to 5 parts by weight of an organic binder to 100 parts by weight of a refractory material consisting of 5 to 20 parts by weight of silicon carbide and 1 to 5 parts by weight of lithium phosphate and/or barium phosphate. Refractories for lining.