JPS61236658A - Manufacture of 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 Field of Industrial Application: The present invention is directed to an excellent industrial furnace that has low lime by adding ultrafine refractory powder, still exhibits strength, and has high refractory properties. The invention relates to a method for producing castable refractories that can be used to form a lining.

Background of the invention/Related technology: Conventional castable refractories using alumina cement have a high reactivity of the cement itself, and in the refractory, for example, anorthite (CaO・k120B・28102) or gehlenite (2CaO-kl, , 08-5in2)
It is difficult to obtain high refractory properties due to the formation of easily meltable materials such as, etc., and this tendency is even more pronounced in heavy-duty materials, where a large amount of gold is added in an attempt to obtain high strength.

As a countermeasure for this, in recent years, the amount of alumina cement blended has been reduced by adding ultrafine powder of refractory material, which has reduced the amount of water used (standard mixed water t) from 15 to 30 wt4 in the conventional case. , 15 wt, castable refractories that can be constructed even with a moisture content of less than 4, and have high strength and high fire resistance (Japanese Patent Application No. 53-21339, Japanese Patent Application No. 1987-
No. 160569) has been proposed. However, these castable refractories, which have a lower lime content due to a reduction in the amount of alumina cement blended, also have drawbacks. ) and curing time may vary,
The material may turn into a flash-setting state with no usable life, or conversely cause poor curing, making it impossible to obtain the original physical properties.Furthermore, such phenomena are affected by the conditions of construction as a castable refractory, especially water temperature, air temperature, etc. It is recognized that there will be a significant impact. The cause of this is thought to be that the amount of alumina cement blended is small, and the alumina cement changes in quality as a whole due to the slight residual moisture in the refractory material powder.This tendency is similar to that seen in conventional examples of alumina cement 20wt4
This seems reasonable considering that in the case of a refractory containing a large amount of carbon dioxide, the O deterioration is only partially suppressed, and the above-mentioned phenomenon is slight.

Additionally, in order to prevent the effects of hydration on the alumina cement, the alumina cement is packaged separately from the refractory material powder, and the alumina cement is first introduced into the mixer during hydration and kneading. It is difficult to disperse, and it is inevitable that the applied product will harden or that local deviations will occur in the obtained physical properties.

Purpose of the invention: In view of the current situation, the present invention completely avoids the effects of water content in refractory materials by reducing the amount of alumina cement blended, and also achieves excellent properties during use and physical properties of the cured product. This was made with the aim of proposing a castable refractory that can be obtained, and by using ultrafine refractory powder and stepwise blending of alumina cement, it has a uniform pot life and hardening characteristics, and maintains the desired physical properties. The purpose of the method is to manufacture castable refractories that are highly versatile.

Structure and Examples of the Invention: Hereinafter, the structure of the method of the present invention will be explained based on various examples.

In the case of the method for producing castable refractories of the present invention, even when a large amount of alumina cement is mixed, it is possible to achieve uniform hardening control and to obtain physical property values with no local deviations. This method is applicable to low-lime castable refractories containing ultrafine refractory powder.

Next, to list composition raw materials suitable for the present invention, the refractory aggregate is not limited to oxides, but may be non-oxides. Generally, electrically fused or high temperature sintered alumina, bauxite, mullite, zirconia, zircon, silica, silicon carbide, cordierite, pitch, graphite, etc. are naturally occurring ores, sandalwood raw materials, or synthetic raw materials. One or more types of the group can be arbitrarily selected.

As the ultrafine refractory powder, one or more selected from the group of alumina, chromium oxide, zircon, zirconia, silica, titanium, etc. with a particle size of 5 to 0.01μ are used.
*Add t and t.

Peptizers are used to improve the dispersibility of ultrafine refractory powder and improve the fluidity of castable refractories, such as sodium tripolyphosphate, sodium hexametaphosphate, sodium ultrapolyphosphate, acidic sodium hexametaphosphate, sodium borate, One or more selected from the group of inorganic salts such as soda carbonate, and organic salts such as sodium citrate, sodium tartrate, sodium polyacrylate, and sodium sulfonate,
Add to the fireproof material and add 0.01~o, awt, *0 on the outside.Additionally, curing time regulators, viscosity regulators, or various 7-dayers, metal powders, etc. may be added as necessary. good.

The alumina cement is preferably in the range of 1 to 4 g zt4, and a blending amount that is considered optimal in terms of workability and desired physical properties is determined depending on the use of the castable refractory. Once this blending amount is determined, 25 to 90 wt% of the amount of alumina cement is thoroughly mixed with the refractory material in advance.
The remaining 10 to 75 Wt$ is attached so as not to come into contact with the refractory material, and is mixed during water addition and kneading. If the amount of alumina cement added during this water-mixing is less than 1 Ovrt4, sufficient curing cannot be achieved, and if it exceeds 75wt8% gold, uniform mixing of the alumina cement becomes impossible and desired physical properties cannot be obtained.

There are no particular limitations on the means for attaching the material so that it does not come into contact with the fireproof material, but for example, Japanese Patent Application No. 59-19646
The container bag can be packed in a polyvinyl alcohol bag that can be soaked in water as shown in No. 9, or the container bag can be filled with fireproof material and alumina cement in a small bag. According to the present invention, it is possible to take appropriate measures such as a method in which the fireproof material and alumina cement in the sachet are mixed and discharged as soon as the bag is opened, or other appropriate measures can be taken as long as moisture absorption of the alumina cement is suppressed. This is an advantageous point.

Example: Castable refractories were manufactured by the method of the present invention using the blending composition shown in Table 1. Fireproof material
The additives and amount of mixed water (/J11 water) at the time of crosstalk are constant, Nα2~5 is an example of the present invention, and for alumina cement, the amount of mixture from the beginning is 25~gOwt, q6 of the required amount of alumina cement. (Na2 is 83 wt,%
, 66 wt4 for column 3 and 50 wt, %, Na for column 4.

5 is 33 wt, and the amount of water mixed during kneading with water is 10
~75wt, Chi (17gt for 2nd, 34w for 3rd place)
t, weight, weight 4 is 5o wt, %, 1 weight 5 is 67wt, chi). In addition, Na1 is obtained by the conventional method, and the alumina cement is mixed in its entirety from the beginning, and seats 6 to 8 are comparative examples in which the amount of alumina cement mixed at the time of mixing with water is less than 10 wt, % or 75 wt, excellent. The amount exceeds the limit.

The curing characteristics of the castable refractories manufactured by these methods and the physical properties of the cured products are shown in Table 2. Examples 2 to 5 of the present invention have the characteristics or physical properties immediately after manufacture and after long-term storage. Almost no difference was observed, and it is clear that the stability is extremely excellent. Comparative Example 1 East 6 similar to the method of the present invention
No. 8 is second to this, and the conventional l1lal exhibits significant deterioration in hardening characteristics and physical properties of the cured product due to long-term storage, and is inevitably difficult to construct.

Effects and Effects of the Invention: When using the castable refractory obtained by the method of the present invention as described above, a thickening agent is first applied by adding water and kneading, and the ultrafine powder refractory is subjected to K-rarization. They begin to repel each other, and the castable refractory becomes fluid.

Next, Ca++ ions added during kneading with water and eluted from the alumina cement, which shows almost no change over time, neutralize the plastering agent, and coagulation and solidification of the ultrafine refractory begins. By coagulating and solidifying this ultrafine powder, the caster pull refractory reaches a strength that allows it to be removed from the frame. Furthermore, 25 to 90 wt changes over time since it has been mixed from the beginning.

Added alumina cement, including alumina cement of 100% or higher, gradually undergoes a water utilization reaction, increasing its strength when it contains water. As a result, the resulting castable refractory structure has physical properties similar to those obtained when using alumina cement that has not changed over time.

If the entire amount of alumina cement and refractory material are mixed together and stored, the surface of the alumina cement particles may lose activity due to residual moisture in the refractory material. t),
The elution of Ca"+ ions is very slow, and the curing time is delayed. Also, when the residual moisture in the refractory material is extremely large, for example when natural raw materials are used, a part of the alumina cement may undergo a hydration reaction. If this occurs, a false agglomeration phenomenon occurs with the refractory material powders that are in contact with each other, and when mixed with water, they exhibit a plastic state and do not dissolve at all.

Additionally, the method of adding the entire amount of alumina cement to the refractory material so that it does not come into contact with the refractory material and mixing it when adding water is difficult to accept from the perspective of preventing dust generation during work in front of the furnace. Since water is added, alumina cement cannot be expected to be uniformly mixed and dispersed in the refractory material powder.

On this point, the method of the present invention, in which a part of alumina cement is mixed during kneading with water, can be expected to act as a priming agent for the start of hardening even if it is not mixed and dispersed uniformly at that time, eliminating the problem of over-mixing. The strength of the hardened product is achieved by the hydration of the alumina cement that has been sufficiently mixed and dispersed with the refractory material from the beginning, thereby ensuring the desired physical properties.

Claims (1)

[Claims] When obtaining a castable refractory, 25 to 90 wt. % or more should be thoroughly mixed and dispersed with the refractory material powder in advance, and the remaining 1.
A method for producing a castable refractory, characterized in that alumina cement of 0 to 75 wt.