JPS6042271A - Manufacture of high purity magnesia sintered body - 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 provides 8203.5i02 in a magnesia sintered body,
The present invention relates to a method for producing a high-purity magnesia sintered body by removing CaO.

Seawater magnesia clinker as a raw material for basic refractories has improved in Ca o, si 02.8 due to improvements in steelmaking technology in recent years.
High-purity clinkers containing few impurities such as 203, At 203, and Fe 203 have become popular.

Among the above impurities, hot bending is known to be a quality factor in magnesia clinker and magnesia brick, and it is desired to reduce this.

Conventionally, methods for producing high-purity magnesia sintered bodies with B20:l and low CaO content by firing magnesium hydroxide obtained by the reaction of seawater and milk of lime include a method of removing boron from seawater; Alternatively, there is an overliming process in which, during the reaction between seawater and milk of lime, a reaction is performed by adding milk of lime in an amount equal to or more than Mg in the seawater.

The method of removing boron from high water requires treating a large amount of seawater, which is disadvantageous in terms of loss. In this case, boron is low, but lime is high.

A method in which magnesium hydroxide is once thermally decomposed to produce magnesia and then CaO is reduced. In this method, magnesium hydroxide is heated at 700 to 1000°C, the generated magnesia is placed in seawater, and the resulting magnesia is separated by precipitation once again. High-purity magnesium hydroxide containing 0.3% or less of CaO is molded and fired at a temperature of 1700° C. or higher, and 8203 is volatilized and reduced.

It is desirable to reduce 8203 in magnesia sintered bodies, which has a particularly negative effect on the hot bending strength as a quality of magnesia bricks, but conventionally, it has not been possible to improve the purity of the composition of manufactured magnesia sintered bodies. When manufacturing magnesia bricks, this composition had to be used as is.

In view of the current situation, the first aspect of the present invention is to produce refractories, other electric vA! With the aim of improving the magnesia sintered body as a raw material clinker for magnesia, the present invention was developed as a result of studies to effectively remove impurities from the magnesia sintered body.

That is, the present invention provides a method for producing a high-purity magnesia sintered body, which comprises bringing a magnesia sintered body containing one or more of B203, Si02, and CaO into contact with water or an aqueous solution, and then separating it from the liquid phase. It is.

1. That is, in the present invention, the magnesia sintered body is brought into contact with, for example, water or an aqueous solution containing one or more organic substances such as acid, alkali, salt, sugar, etc., and then separated from the liquid phase. Water @ Kezuni, Ca 0XB203.51
02. Such a mechanism was proposed in the above-mentioned
The mechanism is different from the mechanism shown in Publication No. 9-40602, and the reduction rate of B203 in water droplet is significantly better.

The present invention is a magnesia sintered body fired at a temperature of 1400°C or higher, and the particle size is fine powder of 1 m/m or less, or if the particle size is 1111/II1 or more, the bulk specific gravity is 2.5.
Applicable to the following magnesia sintered bodies.

In particular, it is suitable for seawater magnesia sintered bodies containing a large amount of B203, but it can also be used for magnesia sintered bodies obtained by firing natural magnesite.

The above-mentioned water or aqueous solution used is preferably an aqueous solution with a pH of 8 or less in order to fully obtain the effects of the present invention,
The contact method requires not only immersing the magnesia sintered body in an aqueous solution, but also stirring or the like to ensure sufficient solid-liquid contact.

The contact time is preferably within 2 days, and in order to prevent hydration of the magnesia sintered body, it is preferable to contact within a short period of time, and 3 to 3 days.
0 minutes, and the contact temperature was lowered to 30℃.
It is better to do the following.

If the contact is made in the above manner, hydration of the magnesia sintered body will not proceed, and by separating the liquid phase, B2
03, Si 02, and CaO can be removed with high efficiency, and I!
The digestion resistance of the produced high-purity magnesia sintered body also does not deteriorate. The high-purity magnesia sintered body thus obtained is used either undried or dried.

In the method of the present invention, 2 of 8203 in the magnesia sintered body
0-90%, 10-80% of Si02, 20% of CaO
~50% is removed. Conventionally, the composition of magnesia sintered bodies was determined by the composition of magnesium hydroxide and natural magnesite, which are obtained by the reaction between seawater and milk of lime, which are the raw materials, so these raw materials were purified, but the present invention According to the report, the magnesia sintered body itself has a high M! degree,
[I can.

This high-purity magnesia sintered body does not require re-firing.
It can be used as a fine powder raw material and fine powder for high-purity magnesia bricks or as a raw material clinker for high-purity fused magnesia.

Next, examples will be given.

Examples 1 to 2 250 g of magnesia clinker powder with a diameter of 0.5 m/m or less baked in a 0-tally kiln at a temperature of 1950°C or higher
0.125N-1-ICI (11140,93/2
7.0°C) 1β, stir for 5 minutes, discard the supernatant, and add water 11! After stirring and washing for 5 minutes, the mixture was filtered and dried in a dryer at 120°C.

As a result, the composition and digestion resistance were as follows. - Example 3 Bulk specific gravity is 2.04 and particle size is 15.9 to 4.00
100g of magnesia sintered body of It/m is 0.035N
-HCI (DH1,50/24.5°C) 1 Place in a container and stir for 30 minutes, then take out the magnesia sintered body, put this sintered body in water at 1°C, stir and wash for 5 minutes, then take out,
It was dried in a dryer at 0°C.

As a result, for the composition of CaO,B203, Example 4~
5. Magnesia clinker calcined at a temperature of 1950°C or higher in a 0-tally kiln is crushed and 100g of tallinker powder with a particle size of 105μ or less is added to 0.035N-"l-
I put it in CI 1β and 1 o'clock li! After stirring, the mixture was filtered and dried for 3 hours.

As a result, the composition f7) Ca 0,820a, T glo
Regarding ss, it was as follows.

Magnesia clinker powder with a diameter of 0.5 m/m or less, baked in a tally kiln at a temperature of 1950°C or higher.
was added to 1β of water (DH7,62/24.5°C), stirred for 1 hour, and filtered. This was dried in a dryer at 120°C.

As a result, the composition was as follows.

Claims (1)

[Claims] A method for producing a high-purity magnesia sintered body, which comprises bringing a magnesia sintered body containing one or more of B2O3, 5107, and CaO into contact with water or an aqueous solution, and then separating the mixture with a liquid phase.