JP2001080942A - Production of alumina cement - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the perfectly recycling of scrapped aluminum possible at an aluminum regeneration factory by firing main materials of aluminum dross waste ash, which is treated as industrial waste, and shells at a specified temperature to produce alumina cement. SOLUTION: The main materials of aluminum dross waste ash and shells are fired at 1,100-1,500 deg.C in a mixed ration of 50-80 pts.wt. shells to 100 pts.wt. aluminum dross waste ash on a dry basis. The aluminum dross waste ash is obtained from the aluminum dross generated in a step to dissolve aluminum or an aluminum alloy after the recoverable metal aluminum content is recovered until the residual metal aluminum content is 5% or below. The residual metal aluminum is successfully reacted with calcium in the shell while restraining the thermit reaction when fired. As a result, the metal aluminum amount remaining in the fired matter can be made very small. High strength and great formability can be achieved when the fired matter is used as cement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to aluminum dross ash generated when aluminum is recovered by re-melting aluminum scrap discarded as industrial waste or re-melting an aluminum ingot, and oysters and pearls. The present invention relates to a method for producing useful alumina cement with shells produced from a shellfish farm.

[0002]

2. Description of the Related Art Aluminum dross is generated when melting or re-melting aluminum metal, aluminum alloy or scraps thereof. The aluminum dross contains metallic aluminum metal, and the remainder obtained by collecting the metal in the aluminum dross is referred to as aluminum dross residual ash. In particular, in the case of scrap, the dirtyer the molten raw material, the lower the metal recovery rate, and conversely, the greater the amount of aluminum dross residual ash generated.

In recent years, recycling has become active and the amount of aluminum scrap dissolved has increased, and the amount of aluminum dross residual ash generated has also increased. On the other hand, the shortage of waste disposal sites has become a serious social problem, and it is easy to expect that waste disposal costs will further increase in the future.

[0004] Aluminum dross residue ash includes light pressure-based residue ash generated from the rolling and extruding industries and alloy-based residue ash generated from castings, die castings and secondary alloys. Although the chemical composition of the light pressure system and the alloy system or the residual ash of the same system differs depending on the generation location, the variation is relatively small if the generation location is the same. Therefore, in the production of alumina cement, aluminum dross residual ash having the same generation location or different ones is mixed at a fixed ratio to stabilize the chemical composition before use.

[0005] The main constituent composition of the alloy-based aluminum dross residual ash is, for example, as follows.

Al ₂ O ₃ : 73.27% (internal metal Al: 33.5%) SiO ₂ : 11.14% (internal metal Si: 4.14%) MgO: 9.93% Fe ₂ O ₃ : 1.60% Na ₂ O: 0.59% K ₂ O: 0.64% On the other hand, the main component composition of light pressure aluminum dross residual ash is
For example:

Al ₂ O ₃ : 94.25% (inner metal Al: 36.3%) SiO ₂ : 0.45% (inner metal Si: 0.11%) MgO: 1.29% Fe ₂ O ₃ : 0.33% Na ₂ O: 074% K ₂ O: 0.10% As a conventional method for treating aluminum dross residual ash, there is a method in which limestone and quick lime are mixed with aluminum dross residual ash and melted to obtain an alumina cement (Japanese Patent Laid-Open No. 52-152928), and aluminum dross and dolomite are used. A method of manufacturing alumina cement by mixing and crushing and firing at 1500 to 1600 ° C (Japanese Patent Publication No. Sho 63-5
7376), add limestone and quicklime to aluminum dross
A method in which calcium aluminate and calcium sulfoaluminate are produced by baking at 0 to 1500 ° C. and used as a quick-setting hydraulic material (Japanese Patent Laid-Open No. 5-294685). There is a method for producing cement (JP-A-63-288932).

On the other hand, shells conventionally treated as industrial waste include scallops, pearl oysters, oyster shells, etc., which are completely different from the fossil shells described in JP-A-63-288932, and the passage of time. In addition, a bad smell is generated. In particular, oyster shells are generated in large quantities from oyster farms and the like, and there is a difficulty in treating them.

[0009] The composition of these shells is mainly calcium carbonate, organic substances attached to the surface, chlorine, silicon,
Etc. are contained. At present, some of them are used as fertilizers, but no definitive reuse method has been found, such as artificial fish reef fish collection cases (JP-A-06-141727) and pet foods for healthy eating (JP-A-07-031381). Use is suggested.

[0010]

SUMMARY OF THE INVENTION The present invention uses light-pressure or alloy aluminum dross residue ash and shells such as oyster shells, which are wastes that are difficult to treat, as starting materials. It is an object of the present invention to develop a method of producing alumina cement which does not use any raw material and which can be fired at a lower temperature than before and can contribute to reduction of energy consumption.

[0011]

A first aspect of the present invention relates to a method for producing an alumina cement according to the present invention, wherein "aluminum dross residual ash and shells are used as main raw materials and fired at a temperature of 1100 to 1500 ° C". Features. According to this, useful alumina cement can be manufactured from aluminum dross residual ash and shells such as oyster shells that have been treated as industrial waste, and scrap aluminum can be completely recycled in an aluminum recycling plant.

In particular, in comparison with the conventional example, it is important that the present invention uses, as one of the main raw materials, not the fossil shellfish but the raw shell after removing the contents. Raw shells are mainly formed of calcium carbonate as described above, but are considered to be microscopically porous with numerous voids and an organic substance filled in the voids. That is, it is a mixture of an inorganic substance and an organic substance, and the organic substance is burned by heat at the time of firing to form a porous calcium carbonate binder, and when it is further oxidatively decomposed, fine CaO with high reactivity is generated. It is presumed that the alumina cement formation reaction proceeds more easily. As a result, the formation reaction of alumina cement is
It is considered that low-temperature firing at (1100 to 1500 ° C.) was made possible.

[0013] Claim 2 relates to the mixing ratio of aluminum dross residual ash and shells. "The mixing ratio of aluminum dross residual ash and shells is 50 to 85 parts by weight of shell per 100 parts by weight of aluminum dross residual ash. In the range. "
For 100 parts by weight of residual amidroshes, corundum (Al ₂ O ₃ ) is generated more when the shell is less than 50 parts by weight in dry weight, and Ca ₂₀ Al ₂₆ Mg ₃ Si ₃ O
_A lot of ₆₈ and mayanite (12CaO.7Al ₂ O ₈ ) are formed and do not become alumina cement.

Claim 3 relates to the type of aluminum dross residual ash. "Aluminum dross residual ash is derived from aluminum dross generated from the aluminum or aluminum alloy melting step.
It is the remaining part of the metal that can be recovered. '' The aluminum dross ash after the metal recovery can be used as a raw material in this way, thus reducing the industrial waste and economical effects. Very high. Here, as the aluminum dross residual ash, the one after metal recovery is mentioned, but naturally, the one before metal recovery can also be used.

Claim 4 relates to the residual metal content in the aluminum dross residual ash, wherein the residual aluminum content of the calcined aluminum dross residual ash is 5% or less. By reducing the residual aluminum metal content to 5% or less by calcination as described above, the thermite reaction at the time of firing can be suppressed and the calcium content of the shell can be reacted well, and the metal remaining in the alumina cement The amount of aluminum can be extremely reduced, and when the fired product is used as cement, it exhibits high strength and high formability.

Claim 5 relates to an average particle size of aluminum residual ash. "Aluminum residual ash subjected to calcination performed prior to sintering with shells is pulverized to an average particle size of 1 mm or less. The feature is.

A sixth aspect of the present invention is characterized in that the average particle size of the crushed shell used for firing is 1 mm or less. The reaction is promoted by setting the average particle size of the aluminum residual ash and the crushed shell to 1 mm or less, and the calcination temperature is low, so that the calcination product remains in the form of powder and granules, and subsequent crushing becomes easy.

[Detailed Description of the Invention] Hereinafter, the present invention will be described in detail. Aluminum dross, which is a raw material of the present invention, is roughly classified into alloy dross and light pressure dross, and alloy dross is a raw material of alumina cement such as magnesium and silica as compared with light pressure dross. Contains many undesirable components. Examples of the composition are as described above.

During firing, magnesium contained in the alloy-based aluminum dross residual ash mainly combines with aluminum to form spinel (Al ₂ O ₃ .MgO). Spinel is very stable and therefore has no adverse effect on alumina cement. Conversely, spinel has high fire resistance and improves the fire resistance of alumina cement.

Similarly, the silica contained in the alloy-based aluminum dross residual ash in a large amount reacts with aluminum at the time of calcination to form gehlenite (2CaO.Al ₂ O ₃ .SiO ₂ ) having no hydraulic property. Spinel and gallenite do not adversely affect the alumina cement, but are not preferable in generating a large amount of calcium aluminate (CaO.Al ₂ O ₃ : hereinafter, CA) which is a main component of the alumina cement. It is. Therefore, it is preferable to use the alloy dross in combination with the light pressure dross rather than using the alloy dross alone.

Since the raw ash of aluminum dross residual ash contains a large amount of metal, an explosive reaction called a thermite reaction occurs when the raw ash comes into contact with iron oxide or the like at a high temperature.
Although the use of this thermite reaction was thought to be effective for the production of alumina cement, it did not react well with the calcium component of the shell in the firing range of 1100 to 1350 ° C, and it did not produce CA, the main component of alumina cement. It was not formed, and some aluminum metal remained.

It is considered that the cause of this is that the metal aluminum of dross is oxidized before reacting with the calcium component of the shell such as oyster shells, so that the environment of the reaction part is in an oxygen-deficient state and the reaction is not promoted. In addition, when metallic aluminum remains in the produced alumina cement, it becomes a foamed material at the time of mixing and does not exhibit sufficient strength, and does not expand to obtain a proper molded product. Therefore, previously oxidizing aluminum dross residual ash is effective for producing alumina cement at a firing temperature of 1100 to 1350 ° C.

As the calcareous raw material to be added to the aluminum dross residual ash, after removing contents such as oyster shells, pearl oyster shells, and scallop shells which are difficult to treat in oysters, pearls, or scallop farms, etc. Most of the shell components are calcium carbonate, and there are differences in the structure of calcite and aragonite depending on the type. However, these structural differences have no effect on the production of alumina cement treated at high temperatures.

The raw shell is mainly made of calcium carbonate as described above, but has a myriad of fine voids and is filled with organic substances and the like, and is microscopically porous. it is conceivable that. That is, it is a mixture of an inorganic substance and an organic substance, and the organic substance is burned by heat at the time of baking to form a porous calcium carbonate composite. And when this is oxidatively decomposed by firing, fine reactive Ca
It is presumed that O is produced and the alumina cement production reaction proceeds more easily. As a result, it is considered that the formation reaction of alumina cement can be performed at a low temperature (1100 to 1500 ° C.) at a low temperature.

Other components include potassium, sodium, chlorine and the like in a small amount, and when there are many deposits on the surface, silica and organic substances are also present. Most of silica and chlorine can be removed by washing with water, and in the case of oyster shells, etc., water is often retained inside even if the surface is dry. It is important to dry sufficiently above ℃. In addition, the organic substances causing the offensive odor are decomposed before reaching the calcination temperature of the cement, so that there is no problem.

It has already been mentioned that chlorine contained in shells can be considerably removed by washing with water. Amidroth residual ash also contains a small amount of chlorine because chlorine gas and chlorine-based flux are used for cleaning and improving the quality of the molten metal. Chlorine is also reduced during the alumina cement firing process, but it is also conceivable that chlorine remains in the finished cement.

In general, when cement is used as a material for reinforced concrete, chlorine has an adverse effect on the reinforcing steel (corrosion).
, The upper limit of the content is specified. However, even if a small amount of chlorine remains in the alumina cement, when used as a refractory, it is a straight concrete that is not used together with a reinforcing bar, so that there is no concern about rebar corrosion and there is no problem.

Next, the manufacturing method of the present invention will be described. First, raw shells and aluminum dross residual ash, which had been pre-oxidized by calcining, were each crushed to 1 mm or less, and then mixed.
Alumina cement clinker is obtained by baking at 100 to 1350 ° C. At this time, the mixing ratio is Al ₂ O ₃ /CaO=1.5 to 2.0
(Weight ratio), the firing time is preferably 60 to 120 minutes at the firing temperature,
Alumina cement is obtained by crushing the clinker to a specific surface area of about 3000 to 5000 cm ² / g.

Firing alumina cement at 1100 to 1350 ° C. is lower in temperature than 1450 to 1600 ° C., which is industrially manufactured, so that it consumes less energy. Since it is not melted into one large block state as in the case, the energy consumption for pulverization is reduced accordingly, which can contribute to energy saving. The pulverized alumina cement is used as it is or after adding alumina or the like, further adding water, kneading, and then hardening.

Hereinafter, the present invention will be described more specifically with reference to examples. "Example 1" Oyster husk 82 parts per 100 parts by weight of pre-oxidized alloy aluminum dross residual ash having the following main composition
A weight part was added and pulverized and mixed in a ball mill at 200 rpm for 1 hour. The amount of one firing was 20 g. This in an electric furnace
The mixture was calcined at 1300 ° C. for 2 hours, and the obtained calcined product was pulverized again with a ball mill at 200 rpm for 2 hours to obtain alumina cement. At this time, the main chemical composition of the aluminum residual ash and the X-ray diffraction pattern of the alumina cement are shown in FIG.

In FIG. 1, the main X-ray diffraction peaks of the product obtained in Example 1 were CA, which is a main compound of alumina cement, in addition to spinel and gehlenite.

(Main Chemical Composition of Oxidized Alloy Residual Ash in Example 1) Al ₂ O ₃ : 68.54% SiO ₂ : 14.44% MgO: 10.63% Fe ₂ O ₃ : 2.72% Na ₂ O: 0.32 % K ₂ O: 0.08% The alumina cement was subjected to a strength test and a fire resistance test. The strength test complies with JIS R2521 (1995), and the fire resistance test is J
This was performed according to a method according to IS R2204 (1991). as a result,
28.5MPa in one day of material age, 32.5MPa in 7th, 28th in 28th
At 34.8 MPa, the refractory temperature was 1480 ° C.

Example 2 Using the same waste raw material as in Example 1, preliminarily calcined alloy aluminum dross residual ash 10
0 parts by weight, 65 parts by weight of oyster shells, 1 in an electric furnace
It was baked at 150 ° C. for 2 hours. Other conditions were the same as in Example 1. FIG. 2 shows an X-ray diffraction pattern of the alumina cement at this time.

In FIG. 2, the X-ray diffraction peak of the product obtained in Example 2 is mainly CA, as well as spinel, gehlenite, corundum (Al ₂ O ₃ ) and mayanite (12CaO · 7Al ₂ O ₃ ).
Met. The strength test and the fire resistance test were performed in the same manner as in Example 1. As a result, the strength at 1 day of the material age was 15.0 MPa, 7
The day was 20.5 MPa, the 28th was 22.7 MPa and the refractory temperature was 1500 ° C.

[Example 3] A total of 336 kg of raw materials obtained by adding 150 kg of oyster shells to 150 kg of light-pressure dross and 36 kg of alloy dross, which had been oxidized in advance, were mixed and then fired in a rotary furnace. The firing conditions were as follows: raw material supply rate 140 kg / hour, furnace rotation speed 1.5 rpm, exhaust gas temperature 1080 ° C, and raw material firing time was approximately
Two hours. The main chemical composition of aluminum residual ash is shown below, and the X-ray diffraction pattern of the obtained alumina cement is shown in FIG.

(Main chemical composition of oxidized light pressure aluminum residual ash in Example 3) Al ₂ O ₃ : 86.57% (including metal aluminum content: 0.56)
%) SiO ₂ : 4.83% (including metal silica content: 0.11)
_{%) MgO: 5.10% Fe 2} O 3: 1.22% Na 2 O: 0.14% K 2 O: 0.03% ( main chemical composition of the alloy series aluminum residual ash obtained by oxidation in Example ₃₎ Al ₂ O 3: 65.76 % (Including metal aluminum content: 1.24)
%) SiO ₂ : 14.90% (of which metal silica content: 3.89)
%) MgO: 12.02% Fe ₂ O ₃ : 2.04% Na ₂ O: 0.11% K ₂ O: 0.06% In FIG. 3, the X-ray diffraction peaks of the product obtained in Example 3 mainly include CA, Spinel, Gehle Knight. The strength test and the fire resistance test were performed in the same manner as in Examples 1 and 2, and as a result, the strength on day 1 of the material was 39.5 MPa, and on day 7 it was 4
At 8.9MPa, the temperature on the 28th was 50.9MPa and the refractory temperature was 1480 ℃.
From the results of Example 3, it was confirmed that the results of the small amount of firing in the electric furnace and the results of the large amount of firing in the rotary furnace were in good agreement.

[0037]

As described above, according to the present invention, aluminum dross residual ash and shells such as oyster shells, which have been difficult to treat, can be treated simultaneously, and alumina cement useful as a refractory raw material can be produced. The obtained cement exhibits sufficient strength in the early stage of the material age, and has a good fire resistance of about 1500 ° C. By using aluminum dross residual ash as a raw material for alumina cement in this way, it becomes possible to completely recycle scrap aluminum in an aluminum recycling factory.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction pattern diagram of a cement manufactured in Example 1.

FIG. 2 is an X-ray diffraction pattern diagram of the cement produced in Example 2.

FIG. 3 is an X-ray diffraction pattern diagram of the cement manufactured in Example 3.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kazumi Murakami 5-5-45 Takachaya, Tsu-shi, Mie Pref., Mie Science and Technology Promotion Center, National Institute of Advanced Industrial Science and Technology (72) Inventor Yukihisa Yuasa 5 Takachaya, Tsu-shi, Mie No.5-45, Mie Prefectural Institute of Science and Technology, National Institute of Advanced Industrial Science and Technology (72) Inventor Keiji Tomii 3-46, Minamikyuhoji, Yao-shi, Osaka Inside Daiki Aluminum Industry Co., Ltd. (72) Inventor Masao Kadoya Osaka 3-46 Minamikyuho-ji Temple, Yao City Daiki Aluminum Industry Co., Ltd.

Claims (6)

[Claims] 1. A method for producing alumina cement, comprising using aluminid residual ash and shells as main raw materials and firing at a temperature of 1100 to 1500 ° C. 2. The mixing ratio of the residual amidroth ash and the shell is as follows:
The shell is 50 to 85 parts by weight on a dry weight basis relative to 100 parts by weight of the residual ash of the amidroth.
The method for producing alumina cement according to the above. 3. The method according to claim 1, wherein the residual amidroth ash is a remaining portion obtained by recovering a recoverable metal component from aluminum dross generated from the aluminum or aluminum alloy melting step. Manufacturing method of alumina cement. 4. The method for producing alumina cement according to claim 1, wherein the calcined aluminum dross residual ash has a residual aluminum metal content of 5% or less. 5. The method according to claim 1, wherein the aluminum residual ash subjected to calcination prior to sintering with the shell is ground to an average particle size of 1 mm or less. A method for producing the alumina cement according to the above. 6. The average particle size of the crushed shell used for firing is as follows:
The method for producing alumina cement according to any one of claims 1 to 5, wherein the diameter is 1 mm or less.