JPS6389452A - Magnesia base refractory material - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to improvement of a magnesia-based refractory material used as a basic refractory material.

(Prior art) Currently, the typical material used for basic refractories is magnesia material, but this magnesia material has many advantages such as high fire resistance and low solubility in basic slag. On the other hand, foreign components such as slag easily penetrate into the tarinker structure, causing alteration and deterioration of the structure.
It has disadvantages such as a high coefficient of thermal expansion. For this reason, shaped and unshaped refractories formed and constructed using these raw materials easily absorb foreign components such as slag during use, forming an altered layer that causes structural deterioration. The current situation is that magnesia materials cannot take full advantage of their original properties, such as the formation of a layer that is different from the raw material, structural peeling similar to thermal spalling, and enlarged lesions.

The microstructure of magnesia clinker produced by the conventional method consists of periclase microcrystals and a silicate matrix surrounding them. Therefore, periclase has a high melting point of 2°C, OOo, and high resistance to basic slag, etc. However, the silicate matrix has a low melting point and high reactivity with slag, so when it comes into contact with slag at high temperatures,
The lag lag easily and in large quantities penetrates into this matrix portion to produce a low melting liquid. Since the periclase microcrystals are surrounded by the low-melting substance that produced the concavity, the structure becomes loose and the slag becomes more easily soaked.

As a result, a thick degraded layer is formed, and a fragile layer is also formed inside, which causes thermal and structural peeling phenomena, leading to major damage.

(Problem to be solved by the invention) In order to improve the above-mentioned shortcomings, currently, 1) Adopt high purity magnesium hydroxide raw material.

■) Increase density by performing high pressure granulation or calcining and high pressure granulation.

■) Perform high temperature firing.

In particular, clinker with high purity and high density is manufactured;

Even if the density is increased, the quality of the clinker basically remains the same, so the easy permeability of the slag during use, that is, the mechanism for penetrating into tissues, will not change, and although there will be some improvement, it will not be enough. The current situation is that the effect has not yet been achieved.

Therefore, in view of the current situation, this invention has been developed to maintain the high heat resistance and low solubility in basic slag that are the characteristics of conventional magnesia clinker, while improving the slag permeability, which is its biggest drawback. The technical objective is to provide a magnesia refractory material with excellent properties as a product.

(Means for Solving the Problems) The present invention was made to solve the above-mentioned problems and technical problems. After coating the particle surface of the magnesia clinker material using fine powder, by firing, a structure in which the zirconia material is interposed in the sintered layer covering the surface surface of the magnesia particle and/or the crystal interface is formed. It is a magnesia-based refractory material characterized by:

To explain this invention in more detail, in order to interpose zirconia on the particle surfaces and grain boundaries of magnesia clinker, the magnesia clinker is coated with a refractory material whose main component is soluble zirconia material and/or finely powdered zirconia, and fired at a high temperature. By forming a strong thin sintered layer of coating material and periclase on the grain surface, and a structure with zirconia interposed at the grain boundaries, cypericlase has high bonding properties and low slag permeability. An object of the present invention is to easily obtain a new and excellent magnesia-based refractory material.

Next, embodiments of this invention will be described.

Example/.

First, sludge-like magnesium hydroxide is heated (at elevated temperature J 0
0”71 p maximum temperature o ooa, maximum temperature hold 2
Calcination is performed in a briquette machine, followed by granulation using a briquette machine to produce granules of IO x 20 x g, and the particles are then primary fired at /100°C/2Ar. Then, g% of magnesium chloride aqueous solution and g% of zirconium oxide powder were added to the particles and mixed for j minutes in a mixer to coat the particle surface. After drying, rotary kiln (
Residence time in rotary kiln, maximum temperature/9 (1'c)
) to obtain a product of the present invention.

Example 2 Grinding magnesite with an impeller breaker,
The particles were subjected to the same particle surface coating process as in Examples, and then fired in a rotary kiln at a maximum temperature of A OCPa for a period of time to obtain a product of the present invention.

Example 3 Modifying the produced magnesia clinker as a raw material - First, magnesia clinker was added to an aqueous magnesium chloride solution with zirconia powder (110μ or less) and mixed with a mixer to coat the particle surface. After drying, the product was fired in a rotary kiln (/woOO°a) to obtain a product of the present invention.

Based on the above examples, a novel magnesia clinker was obtained.

These clinkers are characterized mainly by the formation of zirconia intercalated grain boundaries at the grain boundaries in the surface layer of the MfO particles, and the structure in which a zirconia-coated sintered layer is formed on the surface.

(Effects of the Invention) The novel magnesia clinker produced by the method of each of the above embodiments is characterized mainly by the presence of a sintered thin film of zirconia material on the MfO grain surface and/or the presence of zirconia at the periclase grain boundaries in the grain surface layer. I got the material that made up the composition.

The quality evaluation test results are as follows.

Quality Characteristics Physical Properties Slag Erosion Penetration Test (Immersion Time 30 minutes) Penetration Test Test Conditions Slag with a basicity of 3 from a steelmaking converter is melted in a graphite crucible and immersed in this molten slag. Regarding the particle shape of the magnesia clinker material used in the present invention, it is most effective to use one having a size that does not require a step of crushing the clinker when producing refractories.

As described above, the clinker according to the present invention has a great effect on suppressing the penetration of slag that comes into contact with the zirconia material at high temperatures through coating and intervening, and has a fire resistance that can be improved without impairing the characteristics of the magnesia clinker. material could be manufactured.

The test results of the refractory bricks manufactured using the magnesia clinker obtained in this example are as follows.

Slag erosion test (converter slag medium chain induction furnace lining method, 6 hours) As mentioned above, the amount of erosion is almost the same, and the slag immersion depth is /7. ! ; and very few.

In addition, in the comparison material, generation of cracks was observed at a depth of 20M parallel to the operating surface, but in the example/material, no such occurrence was observed at all.

Claims (1)

[Claims] Consisting of a coating sintered layer formed by coating the particle surface of a magnesia-based refractory material with a refractory material mainly composed of zirconia and then firing it, and/or a permeation layer that penetrates into the structure from the particle surface layer. A magnesia fireproof material characterized by: