JP3194176B2 - Method for producing sulfated radical-containing highly basic aluminum chloride solution - Google Patents

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 sulfate-containing high-basic aluminum chloride (hereinafter referred to as PAC) used for treating industrial water, wastewater, and sewage. More specifically, the present invention relates to a method for producing a PAC which is inexpensive and has excellent storage stability even in a range from room temperature to a relatively high temperature.

[0002]

2. Description of the Related Art A conventional method of manufacturing a PAC can be roughly classified as follows.
Ca in a mixture of aluminum chloride and aluminum sulfate
A method in which a compound is added, or calcium chloride and calcium hydroxide are added to aluminum sulfate, and most of sulfate ions are removed as gypsum to obtain PAC. A PAC is obtained by dissolving a readily soluble alumina gel in sulfuric acid containing hydrochloric acid or an aluminum salt of hydrochloric acid, or dissolving a readily soluble alumina gel in hydrochloric acid or an aluminum salt of hydrochloric acid, and then dissolving the aqueous solution of sulfuric acid or sodium sulfate. A method of obtaining PAC by adding a neutral sulfate. The law makes it difficult to dispose of large amounts of gypsum.

[0003] As a conventional production method in the method, (a) a soluble Al salt is neutralized in an aqueous medium containing an alkali carbonate so as to have a pH of 6.5 to 9.8, and CO ₂ / A
A method in which an alumina gel containing carbonate groups having a molar ratio of l ₂ O ₃ > 0.1 is produced and dissolved in hydrochloric acid or a mixed acid of hydrochloric acid and sulfuric acid.
(B) A method of dissolving a gel obtained by a neutralization reaction of a mixed solution of sodium aluminate and sodium carbonate with aluminum sulfate in basic aluminum chloride. (Japanese Patent Publication No. 63-12645
(C) A method of dissolving an acid-soluble alumina gel obtained by a neutralization reaction between aluminum chloride and sodium aluminate in HCl or aluminum chloride. (Japanese Patent Publication No. 2-4534) and the like are known.

The disadvantages of these methods are that (a) dissolves alumina gel in a free acid, (b) dissolves it in an acidic substance such as aluminum chloride or basic aluminum chloride as shown in (c). In comparison, a large amount of alumina gel must be used twice or more, which requires a large-capacity aluminum gel reactor, and it takes a long time to filter and dissolve the large amount of alumina gel in acid. However, it cannot be said that it is an economical production method. (B) and (c) disclose a method for reacting aluminum sulfate or aluminum chloride with sodium aluminate (or a mixture of sodium aluminate and sodium carbonate) as a method for obtaining an alumina gel. This method is not economical because a large amount of sodium aluminate or sodium carbonate is required as compared with the method using basic aluminum sulfate or basic aluminum chloride instead of aluminum sulfate or aluminum chloride. Further, the alumina gel is converted into a highly basic aluminum chloride simply by dissolving it in an acid or an Al salt, and then converted to PAC by adding a sulfate group. (20 ° C.), it has a fatal disadvantage that it gels or decomposes at an early stage and precipitates when stored at a high temperature such that the liquid temperature becomes 40 ° C. or more even when the solution temperature becomes 40 ° C. or more. In particular, when the PAC has a basicity of more than 70 ° C., the tendency of gelation or precipitation is remarkable.

[0005]

In view of such circumstances,
The present inventors have conducted intensive studies to obtain a PAC that is inexpensive and has excellent stability over time, and as a result, has completed the present invention.

[0006]

That is, the present invention relates to a method for producing a sulfated group-containing highly basic aluminum chloride solution, comprising: (1) a basic aluminum chloride solution having a basicity of less than 50% and a carbonate as an alkali; Or a mixed solution of an alkali aluminate solution and a carbonate at a required ratio, and simultaneously mixing and reacting to form an alumina gel, (2) the alumina gel obtained in the first step,
In a basic aluminum chloride solution having a basicity of less than 50%,
60-75 ° C., second soluble within 2.5-4 hours
(3) a third step of adding a water-soluble sulfate to the basic aluminum chloride solution obtained in the second step, wherein the basicity is 60 to 80% and the sulfate group-containing high basicity. An object of the present invention is to provide a method for producing an aluminum chloride solution.

Hereinafter, the present invention will be described in more detail. In carrying out the present invention, in the first step, a basic aluminum chloride solution and a carbonate as an alkali, or one of a mixed solution of an alkali aluminate solution and a carbonate are simultaneously added at a required ratio and mixed and reacted to form an alumina gel. Generate.
The basic aluminum chloride solution (hereinafter, referred to as BAC) used herein is not particularly limited, but may be represented by the formula A
basicity represented by ln (OH) _m Cl _3n-m [(m / 3
n) × 100] is more than 0 and less than 50%, preferably more than 30% and less than 50%. Thereby, NaCl produced as a by-product during the reaction with an alkali described later
Is reduced as compared with the case where hydrochloric acid or aluminum chloride is used, so that the gel can be easily washed when desalting in a subsequent step.

As the alkali, carbonate or a mixed solution of carbonate and alkali aluminate is used. Sodium carbonate is preferable as the carbonate, and sodium aluminate is preferable as the alkali aluminate. As sodium aluminate, Na ₂ O / Al ₂ O ₃ molar ratio is 1.1 to 1.5,
More preferably, when sodium aluminate of 1.1 to 1.3 is used, not only the amount of by-produced NaCl is reduced, but also the solubility of the generated alumina gel is improved, and the sodium aluminate is inexpensive. .

In carrying out the present invention, a method of reacting BAC with an alkali to produce an alumina gel includes the following methods:
A method in which BAC and an alkali are simultaneously added at a required ratio, more specifically, a method in which pH is added to a reaction vessel filled with water while stirring.
It is essential to adopt a method of simultaneously adding BAC and alkali while maintaining the range of 6 to 9. Conventionally, the method of reacting an acidic aluminum salt solution with an alkali is (b) a method of adding an alkali to the acidic aluminum salt solution. (C)
Contrary to the method (b), a method of adding an acidic aluminum salt to an alkali is known. However, when the methods (b) and (c) are adopted, Al ₂ O ₃ in the reaction system after the addition of the raw material is used. Concentration 5
When a raw material having a concentration exceeding 0.1% is used, the viscosity is increased (gelling) before the raw material is completely added, so that the raw material cannot be synthesized. On the other hand, when the method of the present invention, “the method of simultaneously adding BAC and alkali at a required ratio”, is employed, even if the Al ₂ O ₃ concentration in the reaction system after the addition of the raw materials is about 10%, it is increased. There is no tendency to stick, so that the synthesis can be performed about twice or more in a reaction tank having the same volume as compared with the methods (c) and (b). In addition, the alumina gel obtained by this method is superior to the alumina gel obtained by the methods (c) and (b) in terms of excellent sedimentation upon dilution and standing, and after dilution, Al ₂ O _{3 is obtained} only by simple gradient filtration. Content is 1
A 0% slurry (alumina gel) can be obtained.
Such sedimentation is achieved by using NaCl in alumina gel described later.
In removing, the device and time can be greatly reduced.
Further, by using a carbonate as an essential alkali source, an alumina gel having extremely excellent solubility in BAC can be obtained.

The mixing ratio of carbonate and alkali aluminate varies depending on the basicity of BAC used in the first and second steps, the dissolution temperature in the second step, and the target basicity of BAC.
Mixing is carried out so that the molar ratio of CO ₂ / Al ₂ O ₃ ≧ 0.2 with respect to the total amount of Al ₂ O ₃ in the reaction system when a gel is formed. This makes it possible to obtain a so-called easily soluble alumina gel that easily dissolves in the BAC in the second step.

The alumina gel thus obtained is then dissolved in a low basicity BAC of less than 50%, usually 20% to 50%. The amount of NaCl contained in the alumina gel dissolved in the BAC is Is obtained as a final product
If the molar ratio of NaCl / Al ₂ O ₃ exceeds 1 with respect to the amount of Al ₂ O ₃ in the AC, the NaCl / A
The alumina gel is desalted so that the molar ratio of l ₂ O ₃ is 1 or less. If the final product is NaCl / Al in PAC
_{If the 2} O ₃ molar ratio exceeds 1, 40 to 50 ° C.
Storing at a relatively high temperature as described above is not preferable because PAC causes precipitation at an early stage.

As a desalting method, any method such as filtration and washing, dilution / decantation and the like by a conventional method may be used, but the alumina gel obtained in the first step of the present invention is prepared by diluting / decanting only 10% of Al _2. Since a slurry having an O ₃ concentration can be obtained, no special filter is required, which is extremely advantageous in terms of device efficiency, shortening of operation time, and the like.

In the practice of the present invention, the BAC in the second step
The dissolution of the alumina gel in a specific temperature and at a specific time is essential. In the present invention, the dissolution of alumina gel in BAC is usually carried out by heating BAC heated to about 50 ° C to about 85 ° C.
Alumina gel is gradually added to AC, at least 50-85 at least, regardless of whether the gel dissolution rate is slow.
Hold at a temperature of ° C. for the time shown in FIG. That is, the formula Y = 10 ^(12−0.2X) +2 [log ₁₀ (93−x)] ⁴ , Y ′ = 10 ^(5−0.08X) +0.5 X = 50 to 85 [where Y, Y ′ Is dissolution time (hour), X is temperature (° C)
The treatment may be performed within the range of the dissolution temperature and the dissolution time of the portion surrounded by the line given by If the dissolution time is insufficient at or below the above-mentioned temperature, gelation over time of the final product PAC at room temperature is inevitable. On the other hand, alumina gel
Melting at a temperature of ~ 85 ° C for a predetermined time,
AC does not gel and changes stably with time. Even if the desalted alumina gel is used, if the dissolution time exceeds a predetermined time, the PAC does not gel, but precipitates relatively quickly at a temperature higher than room temperature.
Therefore, when the BAC is 85 ° C. or higher, the alumina gel must be immediately cooled to a predetermined temperature range after addition and dissolved within a predetermined time. It should be noted that the temperature and the dissolution time of the present invention can provide a PAC with excellent stability if the relationship in FIG. 1 is satisfied. However, as is clear from the figure, in the low temperature region around 50 ° C., 10 hours or more, In a high temperature range around 85 ° C., the operation time is as short as several minutes to several tens of minutes. It is desirable to do. Addition of the alumina gel to the BAC causes gelation when a large amount of the alumina gel is added to the BAC solution at a time, so that foaming due to CO ₂ present in the added alumina gel is not remarkable,
Usually, about 5 g (Al ₂
In O ₃ Inuikarada basis) / min to about 10 g / min range, it may be added under stirring BAC solution.

The thus obtained B having an increased basicity
The AC is then converted to PAC by adding a water-soluble sulfate.
Although the amount of the water-soluble sulfate added to BAC is not particularly limited, PAC is usually represented by the formula Al ₂ (OH) _X · Cl _Y
(SO ₄₎ In the composition represented by _Z, Z 0.05
What is necessary is just to add in the range which satisfies 0.5. The mixing temperature of BAC and the water-soluble sulfate is about 85 ° C. or less, preferably about 3 ° C.
It is carried out in the range from 0 ° C to about 70 ° C. Mixing temperature is 85 ° C
In the case described above, the PAC obtained unless cooled immediately decomposes with time, and the tendency to precipitate is increased. The water-soluble sulfate used in the third step may be any of soluble sulfates such as sulfuric acid, aluminum sulfate and sodium sulfate, but it is preferable to use aluminum sulfate. In the practice of the present invention, when the sulfate group is present in the BAC before dissolving the alumina gel, gelation occurs before dissolving all of the alumina gel in a predetermined amount, resulting in high basicity P.
I can't get AC.

[0015]

According to the method of the present invention described in detail above, (1) As a method for producing an alumina gel for obtaining a highly basic aluminum chloride, a carbonate is used as an alkali in a basic aluminum chloride solution having a basicity of less than 50%. Or a method of reacting any one of a mixed solution of an alkali aluminate solution and a carbonate to obtain an alumina gel, which is disclosed in JP-B-63-12645 and JP-B-2-45 mentioned above.
As a method for obtaining an alumina gel, as disclosed in
Compared to a method of reacting aluminum sulfate or aluminum chloride with sodium aluminate (or a mixture of sodium aluminate and sodium carbonate), the amount of sodium aluminate or sodium carbonate used is small and economical. (2) As a method for obtaining highly basic aluminum chloride, a method of dissolving alumina gel in basic aluminum chloride was adopted, as described in Japanese Patent Publication No. 60-8973, which was introduced earlier, to hydrochloric acid or a mixed acid of hydrochloric acid and sulfuric acid. Since the amount of alumina gel used is small compared to the dissolving method, it is possible to reduce the size of equipment such as a reaction tank and a filtration tank for obtaining the alumina gel, and the dissolving time may be short, and as a result, It is economical in terms of equipment and operation. (3) In the method for producing an alumina gel, a method of simultaneously adding and mixing BAC and an alkali at a desired ratio in a desired ratio is employed, whereby alumina having a high Al ₂ O ₃ concentration exceeding 10% and having extremely excellent sedimentation properties is obtained. Since the synthesis is possible without making the gel muddy, the equipment such as the reaction tank and filtration tank for obtaining the alumina gel can be downsized, and the operations such as desalination can be easily performed. It is also economical. (4) Further, a method of dissolving and aging the easily soluble alumina gel containing no sulfate group obtained in the first step in basic aluminum chloride at a specific temperature and for a specific time, and then adding and mixing with a water-soluble sulfate is adopted. As a result, compared with the known method introduced above, not only the stability with time at room temperature is improved, but also a sulfate-containing high base containing extremely few gels or precipitates even when stored at a relatively high temperature. It is possible to provide a neutral aluminum chloride. Basicity of 60 to 8 which is inexpensive and has excellent storage stability in the range from room temperature to relatively high temperature.
It enables the supply of a highly basic aluminum chloride solution containing 0% of a sulfate group, and its industrial value is extremely large.

[0016]

EXAMPLES Hereinafter, the method of the present invention will be described in more detail with reference to examples, but the scope of the present invention is not limited by these examples.

Example 1 In a reaction vessel equipped with a stirrer previously charged with 200 g of water,
Sodium aluminate (Al ₂ O ₃ concentration 26%, Na ₂ O /
An alkaline solution obtained by mixing 185 g of Al ₂ O ₃ = 1.2 mol ratio) and 250 g of sodium carbonate solution (14% concentration);
AC (Al ₂ O ₃ concentration 13.5%, basicity 48%) 43
4 g were simultaneously added at room temperature with stirring while maintaining the pH in the range of 6.5 to 8, to obtain an alumina gel slurry having an Al ₂ O ₃ concentration of 10%. The alumina gel slurry was diluted to 2.9% with water, allowed to stand, and then partially discarded by discarding the supernatant water to make 9.2% of Al ₂ O ₃ and NaCl
1160 g of a 2.6% alumina gel slurry was obtained. The alumina gel slurry (total amount) after the desalting treatment is subjected to BAC (Al
₂ O ₃ concentration 12.7%, basicity 48%) in 600 g 60
The solution was supplied for 30 minutes while maintaining the temperature of ° C., and was then stirred for 3 hours for dissolution treatment (dissolution time 3.5 hours). Subsequently, aluminum sulfate (Al ₂ O ₃₎ was added to the solution.
221 g at a temperature of 60 ° C. and mixed.
After one minute, the mixture was filtered to obtain 1960 g of a transparent PAC solution. The composition of the solution is Al ₂ O ₃ 10.2% sulfate group 2.5%,
Basicity 71.5%, NaCl / Al ₂ O ₃ (molar ratio)
0.26. PAC 150m obtained in this way
1 was collected in a wide-mouthed transparent bottle, kept in a constant-temperature bath at a temperature of 20 ° C. and 50 ° C., and the time-dependent change of the solution was observed. Table 1 shows the results.

Comparative Example 1 A transparent PAC solution was obtained in the same manner as in Example 1 except that the dissolution time of the alumina gel slurry was changed to 1 hour. The composition of the solution is Al ₂ O ₃ 10.1% sulfate group 2.5%, basicity _{71.3%, NaCl / Al 2 O} 3 ( molar ratio) 0.
26. This change in PAC with time was carried out in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 2 A transparent PAC solution was obtained in the same manner as in Example 1 except that the dissolution of the alumina gel slurry and the addition of aluminum sulfate were carried out at 45 ° C. The composition of this solution is Al ₂ O ₃ 1
0.1%, sulfate group 2.4%, basicity 70.9%, NaC
1 / Al ₂ O ₃ (molar ratio) was 0.27. This PA
The change with time of C was carried out in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 3 In a reaction vessel equipped with a stirrer previously charged with 200 g of water,
Sodium aluminate (Al ₂ O ₃ concentration 26%, Na ₂ O /
An alkaline solution obtained by mixing 109 g of Al ₂ O ₃ = 1.2 mol ratio) and 320 g of a sodium carbonate solution (25% concentration);
440 g of AC (Al ₂ O ₃ concentration 14%, basicity 40%)
Was simultaneously added at room temperature with stirring while maintaining the pH in the range of 6 to 9, to obtain an alumina gel slurry having an Al ₂ O ₃ concentration of 8.4%. The alumina gel slurry was diluted to 6.1% with water, allowed to stand, and then partially discarded by discarding the supernatant water to give 8.4% of Al ₂ O ₃ and 8.3 of NaCl.
% Alumina gel slurry was obtained. The alumina gel slurry (total amount) after the desalting treatment was subjected to BAC (Al ₂ O ₃
The solution was supplied to 570 g (concentration: 14%, basicity: 40%) in 30 minutes while maintaining the temperature at 60 ° C., and then further stirred for 7.5 hours for dissolution treatment (dissolution time: 8 hours). continue,
Aluminum sulfate (Al ₂ O ₃ concentration 8%) 37
7 g was added and mixed at a temperature of 60 ° C., and after 30 minutes, the mixture was filtered to obtain 1940 g of a transparent PAC solution. The composition of this solution is A
l ₂ O ₃ 10.3%, sulfate group 4.3%, basicity 60.8
%, NaCl / Al ₂ O ₃ (molar ratio) 0.77. 150 ml of the PAC thus obtained was collected in a wide-mouthed bottle, kept tightly in a thermostat at a temperature of 20 ° C. and a temperature of 50 ° C., and observed over time in the solution. Table 1 shows the results.

[0021] Another did not desalted Comparative Example 4 Alumina gel slurry Comparative Example
In the same manner as in Example 3 , a clear PAC solution was obtained. The composition of the solution is Al ₂ O ₃ 10.2% sulfate group 4.4%, basicity 6
1.2%, NaCl / Al ₂ O ₃ (molar ratio) 1.11. This change in PAC with time was carried out in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 5 In Example 1, the conditions for dissolving the alumina gel slurry in BAC were 80 ° C. for 30 minutes, and then the mixture was rapidly cooled to 40 ° C., and aluminum sulfate was added to the solution and mixed.
A transparent PAC solution was obtained in the same manner except that filtration was performed 30 minutes later. The composition of this solution was 10.2% Al ₂ O ₃ , 2.4% sulfate, 70.9% basicity, NaCl / Al ₂ O ₃
(Molar ratio) was 0.05. This change in PAC with time was carried out in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 6 In Example 1, the conditions for dissolving the alumina gel slurry in BAC were 100 ° C. for 30 minutes, and then the mixture was quenched to 40 ° C., and aluminum sulfate was added to the solution and mixed. A transparent PAC solution was obtained in the same manner except for filtering. The composition of the solution is Al ₂ O ₃ 10.4% sulfate group 2.4%, basicity 70.7%, NaCl / Al ₂ O
₃ (molar ratio) was 0.05. This change in PAC with time was carried out in the same manner as in Example 1. Table 1 shows the results.

Comparative Example 7 BAC (Al ₂ O ₃ concentration 11%,
533 g (basicity: 48%) was added, and sodium aluminate solution (Al ₂ O ₃ concentration: 26%, Na ₂ O / Al ₂ O ₃ ) was added under stirring.
(1.2 mol ratio) and an alkali solution obtained by mixing 350 g of a sodium carbonate solution (10% concentration) with 350 g was added at room temperature to obtain an alumina gel slurry having an Al ₂ O ₃ concentration of 10%. When 70% of the compound was added, gelation occurred, and stirring became impossible thereafter.

Comparative Example 8 The procedure of Example 1 was repeated, except that the addition of aluminum sulfate was performed before the addition of the alumina gel slurry. However, gelation occurred when 80% of the alumina gel slurry was added. Could not be obtained.

[0026]

[Table 1] Note: G indicates the number of days of gelation, and the others indicate the number of days of precipitation.

[Brief description of the drawings]

FIG. 1 shows the dissolution temperature and dissolution time of an alumina gel in a basic aluminum chloride solution, and the range over which the basic aluminum chloride solution obtained by this reaction has excellent stability over time as defined in the present invention. , And the relationship between the dissolution temperature and the dissolution time is shown as a shaded portion.

[Explanation of symbols]

In the figure, Y and Y 'indicate the dissolution time (minutes), X indicates the dissolution temperature (° C.), and Y = 10 ^(12-0.2X) +2 [log ₁₀ (93-x)] ⁴ Y' = 10 ^{(5-0.08 X)} +0.5, X = 50-85.

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshio Ashiya 5-1 Sokai-cho, Niihama-shi, Ehime Sumitomo Chemical Industries, Ltd. (72) Inventor Tatsuya Sakatani 4-1-2 Shigino Nishi, Joto-ku, Osaka-shi No. Asahi Chemical Industry Co., Ltd. (56) References JP-A-47-20096 (JP, A) JP-A-51-49198 (JP, A) JP-A-57-71818 (JP, A) JP-A-54 -32197 (JP, A) JP-A-59-116125 (JP, A) JP-A-55-140718 (JP, A) JP-B-47-40628 (JP, B1) JP-B-48-27601 (JP, B1) (58) Fields surveyed (Int. Cl. ⁷ , DB name) C01F 7/74 C01F 7/56

Claims (10)

(57) [Claims] The present invention relates to a method for producing a sulfated group-containing highly basic aluminum chloride solution. (1) A basic aluminum chloride solution having a basicity of less than 50% and a carbonate as an alkali or an alkali aluminate solution and a carbonate. Any one of the mixed solutions is added simultaneously at a required ratio and mixed to form an alumina gel.
(2) The alumina gel obtained in the first step is subjected to a basicity of 5
60-75 in less than 0% basic aluminum chloride solution
° C., a second step of dissolving in the range of 2.5 to 4 hours, (3) a third step of adding a water-soluble sulfate in basic aluminum chloride solutions obtained in the second step, characterized in that more A method for producing a sulfate-containing highly basic aluminum chloride solution having a basicity of 60 to 80%. 2. The method according to claim 1, wherein the basicity of the basic aluminum chloride solution in the first step is more than 30% and less than 50%. 3. The method according to claim 1, wherein the reaction between the basic aluminum chloride and the alkali in the first step is simultaneously carried out by adding and mixing the basic aluminum chloride solution and the alkali while maintaining the pH in the range of 6 to 9 under water. The method of claim 1. 4. The method according to claim 1, wherein the carbonate in the first step is sodium carbonate. 5. The method according to claim 1, wherein the molar ratio (M ₂ O / Al ₂ O ₃ ) of the alkali aluminate used in the first step is from 1.1 to 1.5. 6. The method according to claim 1, wherein the alkali aluminate used in the first step is sodium aluminate. 7. The method according to claim 1, wherein the basicity of the basic aluminum chloride solution used in the second step is more than 20% and less than 50%. 8. The alumina gel used in the second step is adjusted so that the molar ratio of NaCl / Al ₂ O ₃ becomes 1 or less with respect to the amount of Al ₂ O ₃ in the sulfate-containing basic aluminum chloride obtained as a final product. 2. The method according to claim 1, which is a desalted alumina gel. 9. The method according to claim 1, wherein the mixing temperature of the water-soluble sulfate in the third step is 30 to 70 ° C.
The described method. 9. The method of claim 1 or 9, wherein the water-soluble sulfate in the third step is aluminum sulfate.