JP2003048712A - Method for producing hydrotalcites - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively reutilize waste metallic aluminum, waste alumina and the like by recycling them as hydrotalcites. SOLUTION: Waste metallic aluminum or aluminum hydroxide is dissolved so that the molar ratio of Na2 O/Al2 O3 is controlled to (0.6 to 3.6):1 to prepare an aluminum solution. A carbonic compound is added to the aluminum solution so that the molar ratio of Al/CO3 is controlled to (3 to 2):1. Further, magnesium salt is added thereto so that the molar ratio of Mg/Al is controlled to (2 to 3):1. After that, this solution is reacted at 80 to 100 deg.C for 3 to 24 hr to produce the hydrotalcites.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is discharged from a metal aluminum processing industry, an aluminum foil manufacturing industry, an aluminum capacitor manufacturing factory, a lithium ion battery manufacturing factory, an aluminum sash manufacturing factory, and the like. Emissions from waste metal aluminum, waste metal aluminum, and various aluminum industries, chemical industries that use alumina catalysts, etc., and petrochemical industries, etc., for the purpose of reusing waste metal aluminum and metal-containing aluminum products required to be recycled by the Recycling Law. The present invention relates to a method for producing hydrotalcites from waste alumina and aluminum hydroxide used.

[0002]

2. Description of the Related Art Conventionally, as a method of effectively utilizing these waste aluminum metals, high purity ones are melted and reused by heat, dissolved with an acid to produce a flocculant, and poor quality ones are scrap. The main items were to return to Yamamoto and to use for landfill as scrap.

[0003]

However, the above method is a good method in the case where a large amount of metallic aluminum is used, but the heat melting furnace is large and aluminum is easily oxidized. Active gas, such as nitrogen gas,
It is necessary to use neon, helium, or the like, or to use a reducing gas such as hydrogen gas, which is expensive, and there is a drawback that the energy cost is also high. The method of (1) may generate hydrogen when dissolved in an acid and may explode, and this treatment method has become a problem, and more recently,
Since aluminum is a problem as one of the causes of Alzheimer's disease, aluminum-based flocculants tend not to be used so often. This method is not popular in Yamamoto, and the processing cost is high, which is a big problem. This method is not practical because there are few landfills. Under these circumstances, a more effective recycling method of waste metal aluminum is desired.

Various aluminum industries, chemical industries,
Waste alumina (mainly alumina catalyst) discharged from the petrochemical industry contains organic substances, oils, etc., and therefore it is difficult to dispose of it. At present, most of them are landfilled as waste. However, recently, a shortage of treated land and soil pollution have become problems, and an effective treatment method for waste alumina is desired.

The present invention has been made in order to meet the above-mentioned demands, and in order to effectively reuse waste metal aluminum, waste alumina, etc., industrially advantageous hydrotalcites from waste metal aluminum, waste alumina, etc. It aims at providing the method of manufacturing.

[0006]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies for a long period of time to achieve the above-mentioned object, the present inventors have found that (1) waste metal aluminum is appropriately pretreated. By doing so, it is possible to remove those contaminated by surface treatment, etc. (2) Since aluminum is an amphoteric metal, it can be dissolved in alkali such as caustic soda, and (3) Hydrogen generated during dissolution is a metal oxide. Can be reduced by the addition of (4), (4) using a magnesium salt such as MgO as a metal oxide to be added,
Hydrotalcites can be obtained by heating reaction at 0 to 100 ° C. (5) Ions trapping anions when carbonic compounds such as sodium carbonate and carbon dioxide are added when producing hydrotalcites It was discovered that they have exchange capacity.

If waste alumina is calcined at high temperature together with sodium carbonate, water-soluble sodium aluminate can be obtained. In this case, impurities such as organic substances contained in the waste alumina due to the high temperature baking are removed. Can be removed,
High-purity sodium aluminate can be obtained, and hydrotalcites can be produced as described above by using this sodium aluminate, and further, these methods can be effectively adopted for waste aluminum hydroxide. I found out.

The present invention is based on these findings,
Waste metal aluminum or aluminum hydroxide is dissolved in an alkali so that the molar ratio of Na ₂ O / Al ₂ O ₃ is 0.6 to 3.6: 1 to prepare an aluminum solution, and the carbonate solution is added to the aluminum solution. Was added so that the Al / CO ₃ molar ratio was 3 to 2: 1 and the magnesium salt was added so that the Mg / Al molar ratio was 2 to 3: 1. Provided is a method for producing hydrotalcites, which comprises reacting at a temperature of 3 to 24 hours.

In the present invention, waste activated alumina or aluminum hydroxide is mixed with sodium carbonate into Na ₂ O / Al ₂ O ₃
The first step of mixing so that the molar ratio of the mixture is 0.8 to 1.1: 1, and the mixture is 2 to 12 at 700 to 1250 ° C.
Second step of firing for a time and N obtained by this firing
a ₂ O-Al ₂ molar ratio of O ₃ based compound Na ₂ O / Al ₂ O ₃ is 0.6 to 3.6: and a third step of dissolving in an alkaline solution to a 1, the resulting solution Carbonate compound in Al / C
O ₃ is added in a molar ratio of 3 to 2: 1 and magnesium salt is added in a Mg / Al molar ratio of 2 to 3: 1.
To 80 ° C to 100 ° C for 3 ~
A fourth step of reacting for 24 hours is provided, which provides a method for producing hydrotalcites.

The present invention will be described in more detail below.
The first method for producing hydrotalcites of the present invention uses waste metal aluminum or aluminum hydroxide as a starting material.

Here, the waste metal aluminum is discharged from a metal aluminum processing industry, an aluminum foil manufacturing industry, an aluminum sash manufacturing factory, a lithium ion battery manufacturing factory, an aluminum sash manufacturing factory, etc. Waste metal aluminum, and waste metal aluminum intended for reuse of metal-containing aluminum products required to be recycled by the Recycling Law.

As the first method for producing hydrotalcites of the present invention, the first step of removing impurities from waste metal aluminum by any method such as acid treatment, alkali treatment, or calcination treatment, which is obtained The metal aluminum is N
The second step of dissolving with an alkali such as caustic soda so that the molar ratio of a ₂ O / Al ₂ O ₃ is 0.6 to 3.6: 1, and a carbonate compound such as sodium carbonate and carbon dioxide is added to this aluminum solution. The Al / CO ₃ molar ratio is ₃ to 2: 1, and the magnesium salt such as magnesium oxide has a Mg / Al molar ratio of 2 to 2.
Third step of adding 3: 1, 80-1
It is preferable to include a fourth step of reacting at 00 ° C. for 3 to 24 hours, a fifth step of cooling the reaction solution and separating a reaction product, and a sixth step of washing the reaction product.

Here, in the first step, the waste metal aluminum surface-treated with resin or film is subjected to firing treatment,
Depending on the type of waste metal aluminum, pretreatment methods such as those where an oxide film is formed on the surface or a plating film is formed are treated with acid, and those with oil etc. are treated with alkali. Is selected and impurities are removed.
In this case, the waste metal aluminum from which such impurities have been removed is preferably the one from which impurities have been removed so that the aluminum purity is 90% or more, more preferably 95% or more, and particularly 99% or more. Therefore, if the waste metal aluminum has a purity of 99% or more without such an impurity removal treatment, the pretreatment of the first step can be omitted.

Next, in the step of obtaining the alkaline solution of aluminum in the second step, an alkali such as caustic soda is used so that the molar ratio of Na ₂ O / Al ₂ O ₃ is 0.6 to 3.6: 1. As shown in Table 1, when it is less than 0.6, it is difficult to synthesize hydrotalcite, and 3.6
If it exceeds, the alkali is too strong and OH ⁻ and CO ₃ ^2- become Mg.
This is because it is difficult to enter between —Al bonds, resulting in poor crystallization, and in particular, poor heat resistance and ion exchange ability.

[0015]

[Table 1]

A in the aluminum solution
1 concentration is 20 to 150 g / L, especially 30 to 50 g / L
Is preferred.

Further, in the third step, the molar ratio of Al / CO ₃ is set to ₃ to 2: 1, and especially 2: 1 because the typical rational formula of hydrotalcite is Mg ₆ Al ₂ (OH) ₁₆・ CO
₃ · 4H ₂ O or _{Mg 4.5 Al 2 (OH) 13} · CO 3 · 3.
As can be seen in 5H ₂ O, the Al / CO ₃ molar ratio is 2: 1.
The CO ₃ Increasing the CO ₃ and does not enter the crystal below,
This is because it is wasted because it becomes Na ₂ CO ₃ and remains in the liquid.

Further, the Mg / Al molar ratio is made to be 2 to 3: 1 because unreacted Al (OH) ₃ is generated when the magnesium salt is too small, and Mg (O) is too large.
H) ₂ containing basic magnesium carbonate (MgCO ₃ Mg
This is because (OH) ₂ · CO ₂ ) is generated.

In the reaction step of the fourth step, the reaction temperature is set to 80 to 100 ° C. The reason is that if the temperature is lower than 80 ° C., the reaction is slow, and if it exceeds 100 ° C., the reaction is good, but it is necessary to use an autoclave. Because. The reaction time is 3 to 24 hours, especially 6 to 12 hours.

In the fifth step, the reaction solution obtained in the fourth step is cooled at room temperature, and the reaction product (hydrotalcite) is separated by a means such as filtration. In this case, the separated mother liquor from which the reaction product has been separated can be used as an alkaline solution for the second step to dissolve the waste metal aluminum.

The sixth step is a step of washing the separated reaction product with water or warm water.

Next, the second hydrotalcite of the present invention
The manufacturing method of these products is based on the waste alumina catalyst discharged from various industries.
Waste media such as activated alumina and aluminum hydroxide
Sodium carbonate on activated alumina or aluminum hydroxide
To Na₂O / Al₂O ₃Molar ratio of 0.8 to 1.1: 1
The first step of mixing so that the mixture is 700-1
The second step of firing at 250 ° C for 2 to 12 hours, this firing
So obtained Na₂O-Al₂O₃System compounds as Na₂O /
Al₂O₃The molar ratio of 0.6 to 3.6: 1.
Third step of dissolving with Lucari solution, carbonation of the resulting solution
Al / CO₃The molar ratio of 3 to 2: 1
With addition, the magnesium salt is added to the Mg / Al molar ratio
Is added at a ratio of 2 to 3: 1 and then 80 to 1
4th step of reacting at 00 ° C for 3 to 24 hours, cooling the reaction solution
5th step of removing and separating the reaction product, and further washing this
It is preferable to include a sixth step of

In this case, impurities such as organic substances are removed from the raw material in the firing step of the second step, but if necessary, depending on the degree of contamination of the raw material such as the waste alumina catalyst, the first step of the above-mentioned waste metal aluminum treatment. An appropriate impurity removing method as described in the step can be performed before the first step.

In the sodium carbonate addition treatment of the first step, the amount of sodium carbonate added is Na ₂ O / Al ₂ O ₃
Has a molar ratio of 0.8 to 1.1: 1, especially 0.9 to 1.0:
It is 1. If it is less than 0.8, the production rate of sodium aluminate is poor, and if it exceeds 1.2, it is economically wasteful.

The firing process in the second step is 700 to 1250.
The temperature is preferably in the range of 950 to 1250 ° C., and the alumina is converted into β by such a calcination treatment, so that sodium aluminate is easily formed. The firing time is appropriately selected, but it is preferably 2 to 12 hours, particularly 6 to 12 hours. The firing atmosphere may be air.

The third step is N obtained by the above firing.
a ₂ O-Al ₂ O ₃ based compound (sodium aluminate) a step of dissolving by adding an alkali solution such as caustic soda, which is similar to the second step in the waste aluminized. Further, the addition of the carbonic acid compound and the magnesium salt and the reaction treatment in the fourth step are the same as those in the third and fourth steps in the waste aluminum treatment, and the fifth and sixth steps are also the same as above. , The description is omitted.
The separated mother liquor obtained in the fifth step is preferably used for dissolving the Na ₂ O—Al ₂ O ₃ compound (sodium aluminate) in the third step.

[0027]

INDUSTRIAL APPLICABILITY According to the present invention, waste metal aluminum, waste alumina and the like can be regenerated as hydrotalcites and effectively reused.

[0028]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to the following examples.

[Example 1] 40 waste lithium-ion batteries were used.
It was baked at 0 ° C. for 30 minutes, and 30 kg of waste metal aluminum separated from the carbide was dissolved in 1 g ³ of 150 g / L NaOH solution. After adding 133 kg of MgO to this solution, N
58 kg of a ₂ CO ₃ was added, and 100 rp at 95 ° C.
The reaction was carried out for 6 hours while stirring at m. After cooling and separation, the solid was washed with warm water, dissolved, and filtered again to obtain about 332 kg of solid matter. When this was dried at 100 ° C. and examined by X-ray diffraction, the same pattern as hydrotalcite was obtained. The intensity of the peak indicating the crystallinity was 2-3 times that of the commercial product, and high-quality hydrotalcite was obtained.

Example 2 Waste metal aluminum having a film such as an oxide film or a plating film on the surface of an aluminum sash, an aluminum foil etching waste material, etc. was treated with an acid, and 30 kg of which was removed to obtain 150 g / L. NaO
It was dissolved in 1 m ³ of H solution. Add 133K MgO to this solution
After adding g, 58 kg of Na ₂ CO ₃ was added, and the reaction was carried out at 90 ° C. for 8 hours with stirring at 100 rpm.
After cooling and separation, washing with warm water, dissolution, filtration again, 33
2 kg of solid was obtained. When this was dried at 100 ° C. and examined by X-ray diffraction, the same results as in Example 1 were obtained.

[Example 3] Hydrotalcite is produced by treating waste aluminum products such as oil-waste aluminum sashes and automobile parts with alkali, and reacting the degreased aluminum waste metal under the same conditions as in Example 1. The result was exactly the same.

[Example 4] In the aluminum molding step, the aluminum attached to the die by molding using a die was dissolved in a 150 g / l NaOH solution. The amount of aluminum in the obtained solution was 337.6 g, and the amount of liquid was 6,02.
It was 8 ml. After adding 1,510 g of MgO to this, 662.5 g of Na ₂ CO ₃ was added and reacted at 90 ° C. for 6 hours. At that time, the mixture was stirred at 300 rpm. The obtained solid matter was 3,766 g. When this was measured by the same method as in Example 1, the same result was obtained.

[Example 5] 750 kg of waste alumina for dehydration
And 700 kg of Na ₂ CO ₃ were mixed, and this was mixed with 1 in air.
It was baked at 230 ° C. for 8 hours to obtain 1,083 kg of sodium aluminate. This was dissolved in a NaOH solution so that the molar ratio of Na ₂ O / Al ₂ O ₃ was 2: 1, and MgO was added to this solution so that the molar ratio of Mg / Al was 3: 1. Further, Na ₂ CO ₃ was added so that the Al / CO ₃ molar ratio was 3: 1, and the mixture was reacted at 90 to 95 ° C. for 6 hours. The obtained hydrotalcites were the same as in Example 1 as a result of X-ray diffraction.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mikami Hachijuya             38-1 Komaba, Meguro-ku, Tokyo (72) Inventor Watanabe Daiaki             886-2 Hita, Hita Town, Toki City, Gifu Prefecture (72) Inventor Hiromi Komi             6-22-2 Shimbashi, Minato-ku, Tokyo Horyu             C Kagaku Co., Ltd. F term (reference) 4D004 AA16 AA21 AA43 BA10 CA13                       CA30 CA34 CA41 DA03 DA06                       DA10 DA20                 4G076 AA10 AA16 AB18 AB27 BA30

Claims (6)

[Claims] 1. A waste metal aluminum or aluminum hydroxide is used as an alkali and the molar ratio of Na ₂ O / Al ₂ O ₃ is 0.6.
To an aluminum solution by dissolving the carbonic acid compound at a ratio of 3.6: 1.
O ₃ is added in a molar ratio of 3 to 2: 1 and magnesium salt is added in a Mg / Al molar ratio of 2 to 3: 1.
To 80 ° C to 100 ° C for 3 ~
A method for producing hydrotalcites, which comprises reacting for 24 hours. 2. The production method according to claim 1, wherein the waste metal aluminum having a purity of 99% or more from which impurities are removed is used. 3. The production method according to claim 1, wherein as the waste metal aluminum, one in which impurities are removed by at least one of acid treatment, alkali treatment and baking treatment is used. 4. The separated mother liquor after separating the reaction product from the reaction solution after the reaction is used for dissolving waste metal aluminum or aluminum hydroxide.
Or the manufacturing method according to 3. 5. Waste activated alumina or aluminum hydroxide with sodium carbonate at a Na ₂ O / Al ₂ O ₃ molar ratio of 0.
The first step of mixing so as to be 8 to 1.1: 1, the second step of baking this mixture at 700 to 1250 ° C. for 2 to 12 hours, and the Na ₂ O—Al ₂ O obtained by this baking. The third step of dissolving the ₃ type compound in an alkaline solution so that the molar ratio of Na ₂ O / Al ₂ O ₃ is 0.6 to 3.6: 1; the molar ratio of ₃ 3
~ 2: 1 and magnesium salt at a Mg / Al molar ratio of 2-3: 1, and then reacting at 80-100 ° C for 3-24 hours. A method for producing hydrotalcites, comprising the steps of: 6. The separated mother liquor after separating the reaction product from the reaction solution after the reaction in the fourth step is Na ₂ O—Al ₂ O ₃
The method according to claim 5, wherein the method is used for dissolving the system compound.