JPH07242462A - Cao-containing refractories - Google Patents

Abstract

PURPOSE:To inhibit a slaking reaction of CaO-contg. refractories causing the deterioration of performance. CONSTITUTION:A refractory base material consisting of MgO-CaO stock contg. >=3wt.% CaO and carbonaceous stock is prepd. and metal Mg foil chips each having <=0.1mm thickness and <=10mm diameter or cut metal Mg wires each having <=1mm diameter and <=10mm length are added to the refractory base material by 0.3-8wt.% of the amt. of the base material. Metal Mg having higher activity than CaO captures moisture.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CaO-containing refractory used for a converter, a ladle, a tundish, and a molten metal container such as a hot metal gutter.

[0002]

2. Description of the Related Art MgO-CaO-C refractory or Mg
CaO-containing refractory materials such as O-CaO refractory materials are widely used for refractory lining of molten metal containers such as converters, ladles, tundishes, and hot metal gutters because of their excellent corrosion resistance and heat-resistant spalling resistance.

The refractory base material of the refractory material containing CaO is M
Electrofused magnesia, sintered magnesia clinker, etc. are used as the gO source, and dolomite, magnesia dolomite, electrofused magnesia-calcia, sintered calcia, electrofused calcia clinker, etc. are used as the CaO source, and scaly graphite and pitch are used as the C source. And so on.

Further, in the non-fired product, an organic system of phenol resin, tar pitch, etc. as a binder and hexamine as a curing agent is added.

[0005]

While the CaO-containing refractory is stored, the MgO source, Ca, which constitutes the refractory base material, is stored.
It is known that the water content adhering to each raw material of the O source and the C source reacts with the CaO component to proceed a digestion reaction to produce calcium hydroxide [Ca (OH) ₂ ]. Since such a digestion reaction is accompanied by a rapid expansion of the volume inside the matrix, it leads to performance deterioration such as loose bonding of the matrix and generation of cracks. In some cases, it could become unusable due to damage or destruction.

Further, the phenol resin or tar pitch added as a binder undergoes a condensation reaction in a relatively low temperature range such as the curing process of refractory and the initial stage of operation, and water produced by the condensation is also generated. It is a factor that promotes the digestive reaction.

Further, an inorganic binder such as hexamine
Is used, an amino group (-NH ₂) And the rest
The water in the air is adsorbed by the distillate nitrogen, which
Also promotes the digestion reaction.

The present invention has been made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a CaO-containing refractory material in which a digestion reaction which causes deterioration of performance is suppressed.

[0009]

In order to achieve the above object, the present invention employs the following means. That is, CaO
A refractory base material composed of MgO-CaO-based raw material and carbonaceous raw material containing 3% by weight or more of components, and a metal Mg foil piece having a thickness of 0.1 mm or less and a diameter of 10 mm or less, or a diameter of 1 mm or less and a length of 10 mm or less. 0.3 mm outer metal cut wire
It is a CaO-containing refractory added with ˜8% by weight.

[0010]

According to the above structure, the moisture adhering to the refractory base material,
The water generated by the condensation reaction at the time of curing or the water adsorbed from the air is used as a metal M more active than CaO.
By capturing in the form of Mg (OH) ₂ by g, the digestion reaction of CaO is suppressed.

Since the metal Mg is added to the refractory base material in the form of foil pieces or cut wires, the Mg (OH)
_The volume expansion associated with the formation of ₂ is smaller than the volume expansion associated with the digestion reaction of CaO, and does not adversely affect the matrix structure. Rather, the formation of Mg (OH) ₂ appropriately fills the voids between the refractory base materials, which has the advantage of promoting the densification of the matrix.

Since Mg (OH) ₂ is produced below the melting point (650 ° C.) of metallic Mg, the above action is sufficiently exerted in the temperature range up to 500 ° C. where the digestion reaction of CaO proceeds. .

The CaO component of the refractory material containing CaO to which the present invention is applied is 3% by weight or more, and when the CaO component is less than 3% by weight, the CaO component is coated with phenol resin, tar pitch, etc. added as a binder. Therefore, there is no concern that the performance will be deteriorated due to the digestion reaction, and the effect of the present invention is almost negligible.

Further, as will be described later, the effect of suppressing digestion according to the present invention depends on the relative blending amount of CaO component and metallic Mg, so that other refractory materials such as MgO component and C component are constituted. The ingredients are not specifically defined.

In the present invention, the metal Mg foil piece has a thickness of 0.1.
0 mm or less, 1 mm or less in diameter, and the cut wire of metallic Mg has a length of 10 mm or less and a diameter of 1 mm or less. For larger sizes exceeding these, the volume expansion at the time of Mg (OH) ₂ formation into pores distributed in the matrix. Compared with this, the performance is deteriorated such that it becomes excessively large and causes tissue destruction. Rather, the size of the metal Mg foil piece or the cut wire is preferably as small as possible if a predetermined safety (prevention of spontaneous combustion or explosion) is secured.

Further, it is appropriate that the amount of the above-mentioned metallic Mg added is 0.3 to 8% by weight on the outer side of the refractory base material, and more desirably about 10% of the above CaO component. It has been confirmed that the effect of suppressing digestion is exerted. However, it has also been confirmed that the digestive inhibitory effect is saturated with an upper limit of 8% by weight.

[0017]

EXAMPLES The present invention will be described below based on examples. Table 1 below shows the measurement results of the weight loss rate when each raw material was heated to 1000 ° C. in order to determine the amount of adhering water content of various raw materials blended as the refractory base material.

According to Table 1, adhered water is present in every raw material without exception, and in particular, scaly graphite, which is widely used as a carbonaceous raw material, can retain a large amount of water between the graphite layers. In comparison, it can be seen that the amount of attached water is much higher.

Further, Table 2 below shows the water content of the phenol resin when the temperature is raised, which ranges from RT (room temperature) to 350.
Moisture generated in each temperature range of 350C to 500C and 500 to 900C was measured. The "curing agent" shown in the lower part of Table 2 is hexamine, and the measurement was carried out at a mixing ratio of 100: 10 with the phenol resin.

From Table 2, it can be seen that when the curing agent is blended in the above proportion, the amount of water produced is slightly less than twice that of the phenol resin alone. Table 3 is Table 1 and Table 2 above.
3 shows the respective blending and physical property values of Examples 1 to 4 according to the present invention obtained by blending metallic Mg with various raw materials shown in FIG. 2 and Comparative Examples 1 and 2 not according to the present invention. It should be noted that each raw material shown in Table 3 has one letter in the column in order to correspond to the raw material shown in Table 1.

As shown in the lower column of Table 3, in each of Examples 1 to 4 according to the present invention, the dimensional increase rate after 90 days was lower than that of Comparative Examples 1 and 2, and no crack was observed. It can be seen that the degree of compression strength deterioration is also low, and it can be seen that the digestion reaction was suppressed by the metal Mg added in each example.

The present invention is not limited to the above-mentioned examples, and it goes without saying that the digestion reaction is similarly suppressed when applied to refractory base materials with other blends.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Table 3]

[0026]

INDUSTRIAL APPLICABILITY As described above, by applying the present invention to a refractory material containing a CaO component, it is possible to suppress the digestive reaction that occurs during storage, the curing step, or the initial operation. It has an effect of improving durability afterwards.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C04B 35/74 F27D 1/00 N 7727-4K

Claims (2)

[Claims] 1. A Mg containing 3% by weight or more of CaO component.
CaO-containing, characterized in that a metal Mg foil piece having a thickness of 0.1 mm or less and a diameter of 10 mm or less is externally added to a refractory base material composed of O-CaO-based raw material and carbonaceous raw material in an amount of 0.3 to 8% by weight. Refractory. 2. Mg containing 3% by weight or more of CaO component
A metal Mg cut wire having a diameter of 1 mm or less and a length of 10 mm or less is externally added to a refractory base material composed of an O—CaO raw material and a carbonaceous raw material in an amount of 0.3 to 8% by weight of Ca.
O-containing refractory.