JPS5935067A - Castable refractories - 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 The present invention relates to a castable refractory made by blending silica flour in a fine powder portion in an amount of 1 to 25% by weight.

Traditionally, castable refractories have been produced using acidic refractory raw materials such as synthetic alumina, synthetic mullite, sillimanite, porcelain, bauxite, chamotte, silicon carbide, silicon nitride, natural graphite, and silicon, as well as neutral refractory rough stones with adjusted particle sizes. Alumina cement having hydraulic properties is usually added in an amount of 10 to 16% and is used by kneading it with water. As is well known, castable refractories have a temperature of approximately 7 to
(There is a drawback that the strength decreases due to crystal transformation of CαQ, A, I!2Q3/1QH20, which is an alumina cement hydrate, in the vicinity of 10 to 1.100'O.) In conventional castable refractories, for example, aluminum melting furnace There is a problem in that the parts where the impact is applied when raw materials are introduced into the room are severely cracked, and the cause of this is often due to the decrease in strength near the humidity.The present invention solves the problem of The main feature of this product is that it contains 7% to 98% by weight of refractory particles, 1 to 17% of alumina cement, and 1 to 25% of silica flour.

Next is a table explaining the raw stones used and their usage ratios.The refractory particles are synthetic alumina, synthetic mullite,
Sillimanite, clay shale, bauxite, chamotte, silica stone 1 Silica sand, zircon, silicon carbide, silicon nitride, natural graphite, silicon, etc. Acidic refractory raw material R1, Neutral refractory raw stone or more) Adjust the grain size of the raw stone This is what I did.

Its usage m is 70 to 98% by weight. Commercially available hydraulic calcium aluminate can be used as the alumina cement. It is preferable to use an alumina cement that has as much alumina as possible and has as little Fe203 as possible. The amount used is critical, 1-17%, preferably 5-15%. If it is less than 1%, there is a disadvantage that explosion phenomenon during rapid heating due to the alkali-water reaction is likely to occur. Silica flour is generated in the process of manufacturing zirconia, ferrosilicon, etc. and cannot be obtained. In the case of ferrosilicon, a part of the silicon produced by reducing the raw material silica stone is volatilized, ignited and smoldered, and recovered by a dust collector as amorphous SiO2. That silk 11!2. IA2. The main component is 5to2, which accounts for about 9%, and its size is 8'20.
Contains 11% II'Q20;, MgO, etc. Particle size: Approximately 90% of the particles are smaller than Itt, and the shape of the particles is spherical. Since silica flour is highly reactive, it is thought that it reacts with alumina dimetate and promotes the formation of calcium silicate hydrate, and therefore castable refractories containing silica flour have extremely high dry strength. In addition, cask-pull refractories containing slick silica flour, which has a spherical shape and small particle size, have good fluidity of the water-added mixture, so the added water W can be reduced, and the strength of the constructed body is lower than that of conventional castable refractories. It has the advantage of being significantly more expensive than other products. In addition, if necessary, carboxylic acids such as gluconic acid and oxalic acid, glycerin, casein, cellulose products, phosphates, lignin sulfonates, and hydrochloric acid may also be used.
The addition of
The fluidity of the water-added mixture can be adjusted according to the two operations. In addition, acids such as oxalic acid have the advantage of increasing the hardening strength of the body in cold conditions.

Hereinafter, the effects of the present invention will be specifically illustrated by examples. 1st
The table shows the blending ratios of Examples of the present invention.

Inner method 1 (i 0 x 40
It was placed in a 40mm x 40mm mold and molded while being vibrated.

After being fed for 24 hours after molding, the mold was removed and dried for about 24 hours to obtain a molded product. This molded body was held in a furnace at a predetermined humidity for 3 hours and fired. After cooling the fired product, certain physical properties were determined. The measured values at this time are listed in Table 2. Incidentally, Table 3 lists the chemical composition, particle size distribution, etc. of silica flour.

As can be seen from Table 2, in the castable refractories of the present invention, the molded bodies fired at 800C or 1,000'O have sufficient strength in terms of bending strength and compressive strength. Furthermore, the bending strength and compressive strength are significantly increased compared to the molded product after drying at 110°C. This is 800' for the conventional castable refractory shown in the comparative example.
The castable refractories of the present invention have significantly improved flexural strength and compressive strength compared to those fired at 0 or 1.00()C, which are significantly lower in bending strength and compressive strength than the molded products after zo'c drying. It shows that Furthermore, the castable refractories of the present invention are dense, have high strength, and are resistant to skim ringing, so they have the advantage of being able to be used satisfactorily even in locations with severe usage conditions.

Table 1: Mixing ratio of Examples of the present invention Chapter: Table 3 -413-

Claims (1)

[Claims] In Ichikawa, refractory particles 70-98%, alumina cement 1
-17% and 1-25% of silica flour.