JPS61261273A - Manufacture of aluminum oxonitride 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 method for producing aluminum oxynitride, and in particular, to a method for producing aluminum oxynitride refractories using Al<=rum residual ash as a nitride raw material. This relates to a manufacturing method. .

[Conventional technology]

Conventionally, by heating and sintering a mixture of fine alumina powder and aluminum nitride powder.

It is known that aluminum oxynitride having the chemical formula mA40s·nAIN can be obtained. The aluminum oxynitride obtained in this way has good fire resistance and heat resistance as well as excellent corrosion resistance against molten metal, so it can be used as a refractory material, especially a refractory material used in a reducing atmosphere. It is expected to be used in a wide range of fields.

As mentioned above, aluminum oxynitride can be obtained by heating and sintering a mixture of alumina powder and aluminum nitride powder.

When such a method is used, the obtained refractory is.

It inevitably had to be expensive. The reason for this is that when using the above sintering method, extremely finely adjusted aluminum oxide with a diameter of several μm or less must be used as a raw material, and relatively expensive aluminum nitride powder is used as a nitride raw material. Because you need it.

Therefore, in the production of acid-chambered aluminum sulfur refractories, several methods have been proposed in which Bayer process alumina, which is industrially mass-produced and available at low cost, is used as a raw material. For example, Japanese Patent Publication No. 53-14247 discloses a method of introducing nitrogen into fused alumina by using Bayer process alumina as a raw material and electro-melting it in a nitrogen gas atmosphere. However, with this method, it is difficult to introduce a sufficient amount of nitrogen into alumina, and a refractory with a high nitrogen content cannot be obtained.

Also,! ¥f Publication No. 1040 describes a nitrogen-containing alumina refractory in which metallic aluminum powder is mixed with Bayer process alumina and then electromelted in a nitrogen-containing atmosphere (including the air). In other words, the method described in the publication causes a nitriding reaction to occur in metallic aluminum powder mixed in alumina during electric fusion of alumina to form alkynyl nitride,
This method attempts to introduce this into molten alumina.

Although it is possible to obtain a refractory with a much higher nitrogen content than the method disclosed in Japanese Patent Publication No. 55-14247, it still has the following drawbacks.

That is, in the method described in Japanese Patent Publication No. 52-50040, as described above, metallic aluminum powder is mixed with Bayer process alumina, and this is electrofused in a nitrogen-containing atmosphere (including the air). By doing this, the metallic aluminum powder mixed in the alumina is changed into aluminum nitride, which is then introduced into the molten alumina. If you use , i.e.
When a mixture of Bayer process alumina and metallic aluminum powder is electrofused in the atmosphere, the metallic aluminum powder mixed in the alumina is nitrided and at the same time a considerable portion is oxidized by oxygen in the air. Therefore, the entire amount of metal aluminum powder used is not effectively utilized.

For this reason, there were drawbacks such as difficulty in keeping the nitrogen content of the product constant for each production lot. Therefore, in order to eliminate such drawbacks and effectively utilize the used metal aluminum powder, it is necessary to keep the entire alumina electric melting furnace in a sealed state,
The electromelting operation had to be carried out in a complete nitrogen gas atmosphere inside the furnace, which resulted in complicated operations and increased equipment costs.

[Means for solving problems]

In view of the above-mentioned circumstances, the inventors of the present invention have conducted various studies to develop an aluminum oxynitride refractory that is more efficient and cheaper than conventional methods. We focused on the fact that so-called residual ash, which is produced as aluminum molten residue in melting factories, etc., is mainly composed of fine alumina, and contains nitrogen in the form of A/H. When the ash is melted in an electric furnace in the same way as in the production of ash, the dragon elements contained in the remaining ash are introduced into the molten alkaline very smoothly.

It has been discovered that nitrogen-containing alumina can be obtained. However, as mentioned above, aluminum residual ash is a waste product generated during aluminum melting, and its composition is not necessarily fixed, and its nitrogen content also varies depending on the residual ash, so it is When aluminum oxynitride refractories are produced by tt melting, the amount of nitrogen introduced into the molten product varies, making it difficult to obtain refractories of constant quality.

Therefore, the inventors continued their research.

The nitrogen content can be reduced by adding and mixing Dodo's Alden Su powder, which has been adjusted according to the amount of nitrogen contained in the residual aluminum ash, in advance and melting this mixture. It has been found that it is possible to produce a constant and controlled melt product.

The present invention was made based on the above-mentioned findings.

That is, one aspect of the present invention is a method for producing an aluminum oxynitride refractory by electrolyzing residual aluminum ash or a mixture of residual aluminum ash and alumina.

The method of the present invention will be described in more detail below.

The aluminum residual ash used as a nitrogen raw material in the method of the present invention is a residual aluminum ash obtained by recovering as much metal aluonium as possible from the furnace slag produced in an aluminum smelting factory or foundry, and is produced by the oxidation of molten aluminum. It is mainly made up of fine particles zt O, with about 5 to 15% A/N mixed closely with it, and some other metals Aj remain attached.

In the present invention, the above-mentioned aluminum residual ash is electrofused in its shape, or.

In order to adjust the nitrogen content of the molten product, if necessary, an appropriate amount of alumina raw material is added and mixed, and this mixture is electrolyzed to form an aluminum oxynitride melt. In this case, it is preferable to use commercially available Bayer process alumina, for example, as the alumina raw material to be mixed with the aluminum residual ash. Bayer process alumina has moderate granularity, can be obtained at a relatively low price, and when mixed with aluminum residual ash and electrofused, it has good compatibility with the molten product of the residual ash. 〈The amount of nitrogen in the residual ash is hardly decomposed and is dissolved during alkalinity to form a nitrogen-containing alumina melt.

The mixing ratio of the aluminum residual ash and the alumina raw material may be arbitrarily determined in consideration of the amount of nitrogen contained in the residual ash and the nitrogen content of the molten refractory to be obtained.

Electro-fused 1 9 as in the production of normal electro-fused alumina
For example, it can be carried out using an AC arc furnace using carbon electrodes.

The thus obtained molten material may be poured directly into a mold to produce cast refractories, or the solidified material may be crushed to an appropriate particle size and used as an aggregate raw material for sintered refractories, castable refractories, etc. can do.

〔Effect of the invention〕

As mentioned above, the present invention uses the residual ash generated when melting aluminum in an aluminum smelting factory or foundry as a nitrogen-containing raw material, and also as an alumina raw material to be mixed with the residual ash, which can be obtained in large quantities at low cost. The raw material cost is low, and the residual ash or the mixture of residual ash and alkali can be melted using a sealed electrician in a nitrogen gas atmosphere as in Publication No. 411F Publication No. 52-50040. The equipment cost is low because it does not need to be carried out in a melting furnace and can be carried out in the atmosphere in the same manner as in the production of ordinary fused alumina.

This invention also has many advantages, such as being easy to work with.

〔Example〕

Next, an example of the present invention will be described.

Example 1 Lamb ash in Al (Analysis value: AJ!'!O376L/
N11%, metal A/8%) 20kp OKVA O
The material was melted in a three-phase AC arc furnace at 75 V with 200 people for about 2 hours to obtain an aluminum oxynitride ingot of about 19 kp.

When this ingot was crushed and analyzed, the average N content was approximately 5.7%.

Example 2 Aluminum residual ash (analytical value: A/, 0s75%, A
JFNIL 5%, Metal A/6%) Mix 100fi parts with Bayer process alumina at a ratio of 50314 parts.

This mixture (about 20k) was melted in an arc furnace for about 2 hours in the same manner as in Example 1 to obtain an aluminum oxynitride ingot of about 19kp.

When this ingot was analyzed, the average N content was approximately &1
It was Chi.

Example 3 100 parts by weight of aluminum residual ash similar to that used in Example 2 was mixed with 100 parts by weight of Bayer process alumina, and approximately 201 P of this mixture was heated in an arc furnace in the same manner as in Example 1. After melting for 2 hours, an aluminum oxynitride ingot of about 19k) was obtained.

When this ingot was analyzed, the average N content was approximately 2.
It was 4%.

Claims (1)

[Claims] A method for producing an aluminum oxynitride refractory, which comprises electrolytizing residual aluminum ash or a mixture of residual aluminum ash and alumina.