JPS61122157A - Limy 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 [Industrial Application Field] The present invention relates to a lime-based refractory using natural raw materials such as limestone and dolomite.

[Conventional technology 1 Basic refractories include magnesia, Maguro 1 Maguro,
Examples include bricks such as magnesia carbon and monolithic refractories, which are used in various steelmaking furnaces. However, recently,
The cleanliness of steel is increasingly required, and it is no longer possible to obtain sufficient cleanliness of steel with conventional basic refractories.

For two, come to the molten steel ladle or tandissi λ.

Lime refractories that easily collect inclusions are now being considered. For example, ``Refractories J19B4, Vol. 36, No. 3'' describes the application of lime bricks with CaC1- to molten steel ladles. This ladle for molten steel using lime bricks contains 12Ca of A1□03, S i O2, and S in the steel.
It is reported that it can be absorbed as O・)^1-03.3CaO-SiO2, CaS. In addition, in ``Tetsu to Hagane 4, Vol. 69, No. 12, 1983,'' published by the Japan Iron and Steel Institute, ``cao
Examples such as "Development of technology for application to refractory linings for tundishes" are described, and application to actual tundishes 1 is being considered. The CaO-resistant material used here contains Gael□ as described above, and it is reported that Al2O3* inclusions are reduced in the same way as the CaCl and lime bricks described above.

[Problems to be Solved by the Invention] As mentioned above, lime refractories have excellent properties in absorbing inclusions. At present, it is hardly used for water use.While various studies have been carried out to prevent lime hydration, it has not been possible to prevent water use, and to this day, it has not been possible to prevent the hydration of lime. Currently, various additives are added to limestone IJ inkers to delay hydration, or they are fired at high temperatures, but these operations sacrifice the natural activity of lime. , and the benefits of lime reaction are lost.

As a lime-based refractory that does not use lime clinker, a lime-based refractory that does not use lime clinker is disclosed in Japanese Patent Application Laid-Open No. 53-122055, to which the present inventor is a part.
5-51763), when one or more of silicates and phosphates (e.g., alkali metal silicate, alkali metal phosphate, etc.) are added to limestone, there is almost no shrinkage even after firing (, It is said that active Coo refractories can be made, and there is a disclosure that there is no need to worry about water availability since the product is in the form of limestone until it is used.

Furthermore, in ``Ceramic Data Book J198Q, it was reported that adding CaCl□ to limestone results in less shrinkage during firing (1%) and can be used as a refractory.

However, CaC1□ has a boiling point of 1600 compared to other chlorides.
Ca as a binder in lime refractories for very high temperatures
When Cl2 is used, CaCL becomes a liquid phase in the temperature range for human use, so as shown below as a reference example, it has low hot strength and is easily deformed when subjected to wear or weight from molten steel. There is a problem.

[Means for Solving the Problems] In order to solve the above-mentioned problems of CaClt-containing lime refractories, the present invention investigates inorganic compounds such as various compounds of divalent or higher valent metals other than calcium, and organic compounds. As a result, when chlorides of divalent or higher valent metals other than calcium chloride, especially magnesium chloride, aluminum chloride, barium chloride, or f:A1 iron chloride, are added as a binder to limestone, dolomite, or both, CaC1□-containing This is based on the knowledge that lime refractories with better hot strength than lime refractories can be obtained.

The purpose of the present invention is to use limestone, dolomite, or both as a lime-based refractory raw material without using a lime clinker, and to use one or two molar chlorides of divalent or higher metals other than calcium chloride as a binder. The object of the present invention is to provide a lime-based refractory made by adding the above binder.

The present invention uses 100 parts by weight of limestone, dolomite, or both as a binder, and a chloride of a divalent or higher valent metal other than calcium chloride, particularly one or two of magnesium chloride, aluminum chloride, barium chloride, or N41 iron chloride. It is a lime-based refractory made by adding 0.1 to 20 parts by weight of seeds or more.

[Function] When limestone and dolomite are simply fired, the temperature is 300-900℃.
Decarboxylation takes place between 0 and 1000°C, causing linear shrinkage of about 20% at 1500°C, so it cannot be used as a fireproof structure.
As a result of various studies, it has been found that when the above-mentioned binder is added to limestone, dolomite, or both, the product hardly shrinks even when fired at 1500° C., and can be used as a lime-based refractory.

However, even if the above-mentioned binder is added to magnesite ore, which is an alkaline earth metal carbonate similar to limestone and dolomite, the firing shrinkage rate at 1500"C is as large as 20% or more.
CaO plays an important role, and various binders such as portland cement, alumina cement, boric acid, ammonium sulfate, alumina sol, magnesium sulfate, monobasic magnesium phosphate, paraffin, and ethylene glycol are added to limestone and dolomite. Even if it is added, the firing shrinkage is extremely large and it cannot be used as a fireproof structure.

From this, the binder and CaO used in the lime-based refractory of the present invention interact with each other, inhibiting sintering and suppressing firing shrinkage, thereby achieving hot volume stability at high temperatures. It can be used as a fireproof structure.

The amount of the above-mentioned binder used in the lime-based refractory of the present invention is 0.1 to 20 parts by weight, but if it is less than 0.1 part by weight, the binding force is weak and the refractory will not take shape, causing problems. will occur. Moreover, if it exceeds 20 parts by weight, the corrosion resistance will deteriorate, which is not preferable.

``The limestone and dolomite used in the present invention are not particularly limited as long as they are commonly produced refractory materials.

Corrosion resistance can also be improved by adding lime talinker, dolomite clinker, and magnesia clinker to the above-mentioned limestone and dolomite. The amount decreases, and the cleanliness of the molten steel decreases. However, the corrosion resistance of lime-based refractories also differs depending on the steel type; for example, it is inferior to aluminum guild steel, high-manage steel, and cane steel. It is also possible to add less than 100 parts by weight of lime tallinker, dolomite clinker, or magnesia clinker.

The lime-based refractories of the present invention can be used to obtain refractory structures as unburned bricks or monolithic refractories made by spraying, coating, pouring, or the like. It is also possible to add commonly used plasticizers or hardeners to improve the workability of brick manufacturing or monolithic refractories.

[Example 1 Limestone 2-0.3 am 70 weight ji 1 part, 0.3 Il 1
Adjust the particle size to less than 1 and 30 parts by weight, add various binders,
Table 1 shows the results after firing at 1500° C. using a sample molded to a size of 5()φX 50 m+++1lIIi.

Effect of the invention 1 As is clear from Table 1 above, the firing line change rate of lime-based refractories containing magnesium chloride, aluminum chloride, barium chloride, and ferrous chloride is extremely low, and the apparent porosity is extremely low. It becomes a fireproof structure with high thermal insulation properties. However, all of the comparative examples that use compounds other than chlorides as binders show large #l change rates of 10% or more, which means that when used as refractories, hot This indicates that the volumetric stability of the material is not obtained, making it unsuitable for use as a fire-resistant structure.

Furthermore, the lime-based refractories of the present invention have much higher hot bending strength than those using CaCl2 as a binder described as a reference example, and have a much higher hot bending strength than the conventionally used Ca11. It can be seen that it is superior to lime-based refractories containing lime.

Therefore, in addition to adding known alkali silicate salts, alkali phosphate salts, or calcium chloride to limestone and dolomite, we can also add chlorides of divalent or higher valent metals other than calcium chloride,
In particular, magnesium chloride, aluminum chloride, barium chloride, and ferrous chloride can also provide similar or better effects.

In addition, since the lime-based refractory of the present invention is rich in extremely active CaO, it is better at absorbing inclusions such as A I 203, P, and S in molten steel than lime bricks left behind by sintered lime clinker. It was something that existed.

The effects of the present invention can be summarized as follows.

(It is a lime-based refractory that does not have to worry about hydration during storage and construction.)

(2) Active CaO adsorbs inclusions in molten iron and molten steel.

(3) Adiabatic ms can be obtained due to the porous structure after decarboxylation.

Claims (1)

[Claims] One or more of magnesium chloride, aluminum chloride, barium chloride, or ferrous chloride is added as a binder to 100 parts by weight of limestone, dolomite, or both.
A lime-based refractory containing 1 to 20 parts by weight.