JPH11302010A - Production of hauyne from aluminum ash - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a hauyne in a high yield by pulverizing an aluminum ash to separate an aluminum compd. layer on the surface, adding and mixing an oxygen-contg. calcium compd. and gypsum to the ash, further adding a caustic alkali and water, and firing at a specified temp. SOLUTION: An aluminum ash (having about <=0.1 mm grain size) is pulverized to separate an aluminum compd. layer on the surface, and gypsum and an oxygen-contg. calcium compd. such as calcium hydroxide are rapidly added and mixed to the pulverized material. The amt. of the oxygen-contg. calcium compd. is about 35 to 50 pts.wt. expressed in terms of calcium oxide, and the amt. of the gypsum is about 35 to 50 pts.wt. based on 100 pts.wt. of the aluminum ash. Further, about 50 to 500 pts.wt. of water and about 1 to 10 pts.wt. of a caustic alkali such as sodium hydroxide are added to 100 pts.wt. of the total aluminum ash, oxygen-contg. calcium compd. and gypsum. The mixture is calcined at 1000 to 1350 deg.C to produce the hauyne. Thereby, the aluminum ash conventionally treated as a waste can be effectively used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing Irwin using aluminum ash generated by aluminum refining or the like, particularly, finely divided aluminum ash, which has been almost conventionally disposed of, as a main raw material.

[0002]

2. Description of the Related Art Aluminum ash generated when aluminum is produced or recovered from aluminum refining or aluminum scrap is mainly composed of metallic aluminum, but is usually aluminum oxide, aluminum nitride, and aluminum carbide. Since such aluminum compounds are formed on the surface of aluminum ash, they are mainly disposed of in landfills with little reuse except for those having a particularly high content of metallic aluminum. At the time of disposal, when the aluminum ash comes in contact with water such as rainwater, ammonia or hydrocarbons may be generated. Therefore, a treatment for preventing this is required, and labor and cost for the treatment are required.

[0003] Although even aluminum ash having a low content of metallic aluminum is recycled without disposal, only a small amount is reused as an aluminum oxide source. This is because the aluminum oxide and other aluminum compound layers formed on the surface of the aluminum ash are extremely stable and prevent the progress of oxidation to the inside, so that it is extremely difficult to oxidize the entire aluminum ash. . Generally, the surface energy becomes higher as aluminum ash of fine powder,
There is a strong tendency to easily and rapidly form a surface layer made of such an aluminum compound upon contact with the atmosphere or the like.

On the other hand, as an effective use of the aluminum ash, it has been studied to utilize the aluminum ash as a source of aluminum oxide which is a raw material for producing Irwin which is a hydraulic substance. However, metallic aluminum in aluminum ash is a strongly reducing substance, and when calcined together with gypsum, a raw material component necessary for Irwin formation, the firing atmosphere becomes a reducing atmosphere and gypsum is decomposed, and the decomposed gypsum component forms Irwin. It has been difficult to use directly to produce calcium aluminate which inhibits the activity. As a countermeasure for this, it has been considered to convert aluminum ash into aluminum oxide in advance. In other words, a method is known in which aluminum ash is previously heat-treated in an atmosphere containing oxygen and then oxidized to the inside to use as a raw material.However, all metal aluminum having a stable oxide layer formed on the surface is oxidized. It is not easy to convert to an object, for example, it is necessary to heat in an atmosphere having an oxygen concentration much higher than that of air. Furthermore, there is a method of directly oxidizing aluminum ash using an oxidizing agent, but it may take a long time until the oxidation reaction is completed, and when a strong oxidizing agent is used to shorten the reaction time, There are restrictions on handling and processing,
Both have little production advantage.

[0005]

DISCLOSURE OF THE INVENTION The present invention relates to the use of aluminum ash as a source of aluminum oxide for Irwin production from the viewpoint of effective recycling of aluminum ash. The aluminum compound layer containing stable aluminum oxide as a main component is easily and inexpensively and easily removed without affecting other Irwin-forming raw materials. It is intended to provide a method for manufacturing Irwin.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, when converting metallic aluminum and its compounds in aluminum ash to aluminum oxide as a raw material for producing Irwin, the inventors have found that this problem has been hindered. It has been found that aluminum compounds mainly composed of aluminum oxide formed on the surface layer of aluminum ash can be easily separated from metal aluminum inside aluminum ash by grinding aluminum ash instead of the conventional chemical method, and The fine powder composed of the aluminum compound mainly composed of the removed aluminum oxide can be used as a raw material for producing Irwin even if it is mixed with metallic aluminum powder.
Further, an aluminate and / or aluminum hydroxide which is easily oxidized by adding an inorganic salt having calcium and oxygen as main constituents and water to the highly active metallic aluminum from which the aluminum compound of the surface layer has been removed by the pulverization. If the mixture of these products and gypsum is calcined, the product can be easily converted to aluminum oxide, and gypsum can be formed in high yield without being decomposed by calcining. The inventors have found that the present invention can be performed, and have completed the present invention.

That is, the present invention is a method for producing Irwin from aluminum ash represented by the following (1) to (4).
(1) Aluminum ash is pulverized to separate an aluminum compound layer on the surface, an oxygen-containing calcium compound and gypsum are added to and mixed with the pulverized product, and a mixture obtained by adding caustic alkali and water to the mixture at 1000 to 1350 ° C. A method for producing Irwin from aluminum ash, characterized by firing. (2) The method for producing Irwin from aluminum ash according to (1) above, wherein the particle size of the aluminum ash before pulverization is 0.1 mm or less. (3) A mixture composed of aluminum ash and an oxygen-containing calcium compound is pulverized to separate an aluminum compound layer on the surface of the aluminum ash.
A method for producing Irwin from aluminum ash, wherein the method is calcined at 1350 ° C. (4) The method for producing Irwin from aluminum ash according to the above (3), wherein the particle size of the aluminum ash before pulverization is 0.1 mm or less.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The source of aluminum ash used in the present invention is not particularly limited, but aluminum ash generated in the process of melting and regenerating aluminum, aluminum ash generated during the disposal of aluminum products, and the like can be used. . Prior to use, it is desirable to remove a mixture other than the metal aluminum and the aluminum compound by a known method, if necessary, for example, by removing other metal impurities by magnetic separation or the like. In general, the content of metallic aluminum in aluminum ash tends to include more metallic aluminum as the particle size increases, and aluminum ash having a large metallic aluminum content is often reused as an aluminum metal raw material. In the present invention, aluminum ash having a relatively high content of metallic aluminum and having a large particle size can be used, but aluminum ash having a small particle size, which has been conventionally discarded, has a higher reaction activity. It is preferable because it is easy. Preferably, aluminum ash having a particle size of 0.1 mm or less is used.

As described above, the stable film made of an aluminum compound such as aluminum oxide on the surface of aluminum ash is almost or completely removed by crushing the aluminum ash to obtain aluminum ash particles having metal aluminum exposed on the surface. . The pulverizer used for pulverizing the oxide film on the aluminum ash surface layer is not particularly limited as long as it is a known pulverizer or a particle grinder, but for example, a ball mill, a vertical roll mill, or the like can be used. The pulverization time depends on the particle size of the material to be pulverized, the processing amount, and the pulverizer, but may be about 10 minutes or more. In the case of pulverization, a mixture of aluminum ash and an oxygen-containing calcium compound may be pulverized in addition to the case where aluminum ash is used alone.

In the present method, in the former case, the oxygen-containing calcium compound and gypsum are added to the pulverized aluminum ash or the mixed and pulverized product of the pulverized aluminum ash and the oxygen-containing calcium compound. Further, water and caustic are added to the mixture, followed by mixing and stirring. In the latter case, gypsum, water and caustic are added and mixed and stirred. It is desirable that the addition and mixing of the components be performed promptly after grinding the aluminum ash. Here, the oxygen-containing calcium compound is a source of calcium that forms Irwin, for example, calcium hydroxide,
Any calcium salt, such as calcium carbonate, calcium oxide, or calcium phosphate, containing oxygen as a constituent substance can be used as long as it is an inorganic salt. Preferably, calcium oxide having high reactivity is used.
The caustic alkali is not particularly limited, and for example, sodium hydroxide, potassium hydroxide and the like can be used.
The compounding amount of the oxygen-containing calcium compound per 100 parts by weight of aluminum ash is 35 to 50 in terms of calcium oxide, even when added simultaneously with aluminum ash or after pulverization of aluminum ash.
Parts by weight and the added amount of gypsum are 35 to 50 parts by weight.
Any of the above amounts is not preferable because excess calcium content and excess sulfate which do not contribute to Irwin formation are precipitated at the time of Irwin formation, and the amount of reaction required for Irwin formation is insufficient if the addition amount is less than these amounts. And
It is not preferable because the rate of Irwin formation with respect to the amount of the reaction raw material is reduced. The amount of water added is 50 to 5 with respect to 100 parts by weight of aluminum ash, oxygen-containing calcium compound and gypsum in total.
00 parts by weight, the amount of caustic added is 1 to 100 parts by weight of aluminum ash, oxygenated calcium compound and gypsum in total.
10 parts by weight. If the amount of water or caustic added is less than this, the entire amount of metallic aluminum does not contribute to the reaction for producing Irwin, and a part of the metal aluminum may remain unreacted. On the other hand, if the amount of water exceeds 500 parts by weight, the amount of water that does not contribute to the aluminate formation reaction becomes excessive, which is not preferable. The aluminum ash from which the aluminum compound in the surface layer has been removed quickly reacts with the oxygen-containing calcium compound and water to generate hydrogen gas and an aluminate which is an easily oxidizable substance. Also, aluminum compound fine powder containing aluminum oxide as a main component, which is removed from the surface of the aluminum ash during pulverization of aluminum ash and mixed in the pulverized material, can be used as a raw material for Irwin. The contained aluminum nitride reacts very easily with the added water to produce ammonia gas and aluminum hydroxide which is an easily oxidizable substance.

The mixture containing the aluminate and aluminum hydroxide produced by the above reaction is desirably dried, and then dried in air or an oxidizing atmosphere at 1000 to 1350.
Firing at ℃ to produce Irwin. The firing temperature is 1
If the temperature is lower than 000 ° C., Irwin is not sufficiently formed and 1350
If the temperature exceeds ℃, it is not preferable because of melting.
Further, it is not preferable that the gypsum is decomposed in a reducing atmosphere. Desirably, calcination is performed at a temperature of 1200 to 1300 ° C. where Irwin excellent in both properties and yield can be easily obtained.

[0012]

EXAMPLES [Example] Aluminum ash comprising the components (% by weight) shown in Table 1 was pulverized by a batch ball mill, and the pulverized product was immediately classified to obtain particles of 0.1 mm or less.

[0013]

[Table 1]

To 52 Kg of the classified particles, 27 Kg of calcium oxide and 21 Kg of anhydrous gypsum were added and mixed with a Nauter mixer. 300 kg of water was added to the mixture, and 5 kg of sodium hydroxide was further added, followed by stirring for about 15 minutes.
After stirring, the mixture was left for a while, and after the reaction was completed when no generation of vaporized gas such as hydrogen gas was observed, that is, about 30 minutes after stirring, it was dried at 105 ° C., and dried for about 5 minutes.
Granules of 〜１０10 mm were molded with a pan pelletizer. The granules are placed in a rotary kiln at about 1300 ° C in air for 6 hours.
It was baked for 0 minutes. The produced phase of the obtained fired product was examined by powder X-ray diffraction (CuKα). As a result, a large amount of Irwin was generated, and none of the used raw materials and intermediate products such as aluminum metal, aluminum nitride, aluminum hydroxide, and calcium aluminate were detected.

COMPARATIVE EXAMPLE 27 kg of calcium oxide and 21 kg of anhydrous gypsum were added to 52 kg of aluminum ash having an average particle diameter of 1.2 mm, which was not subjected to pulverization and classification, and was subjected to Nauter mixer. Mixed. 300 kg of water is added to the mixture, and 5 kg of sodium hydroxide is further added.
And stirred for about 15 minutes. Leave for a while after stirring,
When about 60 minutes have passed since the stirring, the temperature was raised to 105 ° C.
After drying, granules having a size of about 5 to 10 mm were formed using a pan pelletizer. The granules were calcined at about 1300 ° C. for 60 minutes in air using a rotary kiln. The phase of the obtained fired product was examined by powder X-ray diffraction (using CuKα ray). As a result, although Irwin was produced, the amount produced was significantly smaller than that of the above-mentioned Example, and calcium aluminate was also detected.

[0016]

Industrial Applicability According to the present invention, aluminum ash mainly disposed of in landfill can be sufficiently used as an aluminum oxide source material as a main component for producing an Irwin-based hydraulic material. Can be effectively used.

Claims (4)

[Claims] 1. An aluminum ash is pulverized to separate an aluminum compound layer on the surface, an oxygen-containing calcium compound and gypsum are added to the pulverized product, mixed, and a mixture obtained by adding caustic alkali and water to the pulverized product is 1000 to 1350. A method for producing Irwin from aluminum ash, characterized by firing at a temperature of ° C. 2. The method for producing Irwin from aluminum ash according to claim 1, wherein the particle size of the aluminum ash before pulverization is 0.1 mm or less. 3. A mixture comprising aluminum ash and an oxygen-containing calcium compound is pulverized to separate an aluminum compound layer on the surface of the aluminum ash, and a mixture obtained by adding gypsum, caustic alkali and water to the pulverized product is subjected to a temperature of 1000 to 1350 ° C. A method for producing Irwin from aluminum ash, wherein the method is sintering. 4. The method for producing Irwin from aluminum ash according to claim 3, wherein the particle size of the aluminum ash before pulverization is 0.1 mm or less.