JP6845195B2 - Highly basic aluminum chloride - Google Patents

Description

The present invention relates to highly basic aluminum chloride, a water treatment flocculant composition containing the same, and a method for producing the same.

In recent years, the concentration of aluminum in drinking water has been regulated, and the World Health Organization (WHO) drinking water quality guideline is 0.2 mg / L, which is the Safe Drinking Water Act Class 2 Drinking Water Regulation of the US Environmental Protection Agency. The European Union's drinking water quality standards stipulate a guide level of 0.05 mg / L and a maximum permissible concentration of 0.2 mg / L.

On the other hand, in Japan as well, Al is indicated in the comfortable water quality item of the standard regarding tap water quality set by the Ministry of Health, Labor and Welfare, and the target value is set to 0.2 mg / L or less.

In order to convert river water into drinking water, a coagulant for water purification using basic aluminum chloride is usually used, and this basic aluminum chloride generally reacts hydrochloric acid and aluminum hydrate under pressure. The basic aluminum chloride is obtained, and sulfuric acid or a water-soluble sulfate is added thereto to produce sulfate-containing basic aluminum chloride (PAC). The basicity is 40% to 60%.

Further, as a manufacturing method for increasing the basicity and improving the aggregation performance, there is a method disclosed in Patent Document 1 (Patent 6186528). That is, it is a method in which an alkali (sodium carbonate, sodium aluminate, etc.) is added to basic aluminum chloride to gel it, and then this gel is added to a basic aluminum chloride solution and dissolved to obtain highly basic aluminum chloride. In this case, it has been shown that basic aluminum chloride having a high basicity of about 73% can be obtained. This method is hereinafter referred to as a gel method.

Japanese Patent No. 6186528

A highly basic aluminum chloride flocculant with increased basicity and improved aggregation performance has the advantage that there is little variation in aggregation characteristics due to fluctuations in river water, and it is possible to reduce residual Al, etc. by increasing the basicity to the utmost limit. Although it can be expected to be a solid flocculant, the invention of Patent Document 1 has a problem that when the basicity of basic aluminum chloride is increased, the viscosity rapidly increases when the basicity exceeds 75%. ..

Recently, the water quality standards for drinking water have become stricter, the content of organic components is as small as possible (evaluated by the value of E260), and biologically-derived fine particles such as cryptosporidium and picoplankton (evaluated by the number of fine particles). It is hoped that the value will be extremely low.

We, repeated extensive studies, the results of investigation of the improvement of the alumina gel method, the content of SO ₄ aluminum chloride first solution of raw materials during the alumina gel, aluminum chloride to dissolve the alumina gel _{Set the SO 4} content in the second solution to 0 to 0.1 in terms of _{the molar ratio of SO 4} / Al ₂ O ₃ , and add alkali carbonate to the dissolved basic aluminum chloride solution to complete the reaction. By increasing the basicity to 80 % to 90 % and performing the dissolution and aging of these under heating at 40 ° C to 80 ° C, a highly basic aluminum chloride solution that is extremely stable despite the high basicity can be obtained. The present invention was completed by finding that it can be obtained.
that's all

Then, by using the obtained highly basic aluminum chloride as a flocculant, the residual Al concentration in the purified water after the treatment, the number of fine particles derived from microorganisms, and the E260 value indicating the content of organic substances are all remarkably increased. I succeeded in lowering it.

An object of the present invention is to provide such highly basic aluminum chloride and a coagulant for water purification using the same, and to provide a coagulant capable of reducing the number of fine particles and the E260 value as well as reducing residual Al. To do.

That is, in the present invention, the composition is M / Al ₂ O ₃ (molar ratio) = 0.8 to 2.2 (M indicates the number of moles of alkali metal), E / Al ₂ O ₃ (molar ratio) = 0. ~ 0.3 (E indicates the number of moles of alkaline earth metal), Cl / Al ₂ O ₃ (molar ratio) = 1.0 to 3.0, SO ₄ / Al ₂ O ₃ (molar ratio) = 0 It is a highly basic aluminum chloride having a basicity of about 0.26 and a basicity of 80 % to 90%.

The present invention is further characterized by further containing a Si compound of Si / Al ₂ O ₃ (molar ratio) = 0.001 to 0.1.

Furthermore, the present invention is a water treatment flocculant, which comprises the above-mentioned highly basic aluminum chloride in water in an amount of 8% by weight to 12% by weight in terms of _{Al 2} O _3.

According to the present invention, the basicity of basic aluminum chloride can be increased from 80 % to 90 %, the storage stability is excellent, and by using it as a coagulant, the residual Al, E260 in purified water after treatment can be used. Both the value and the number of fine particles can be significantly reduced.

In the present invention, the composition is M / Al2O3 (molar ratio) = 0.8 to 2.2 (M indicates the number of moles of alkali metal), E / Al2O3 (molar ratio) = 0 to 0.3 (E is The number of moles of alkaline earth metal is shown), Cl / Al2O3 (molar ratio) = 1.0 to 3.0, SO4 / Al2O3 (molar ratio) = 0 to 0.35, and the basicity is 80 % to 90. % Is highly basic aluminum chloride.

In the present invention, the alkali metal overbased chloride in aluminum, to _Al 2 _{O 3} 1 mol, 0.8 to 2.2 mol, preferably included 1.3 to 1.9 moles. If the amount of the alkali metal is _{less than 0.8 mol with respect to 1 mol of Al 2} O ₃₁ , the effect of sufficiently reducing the number of residual Al, E260 and fine particles cannot be sufficiently obtained, and if it exceeds 2.2 mol, the viscosity is increased. It becomes difficult to manufacture.

In the present invention, examples of the alkali metal represented by M include lithium, potassium, sodium and rubidium, and potassium and sodium are preferable.

Further, in the present invention, overbased alkaline earth metal chloride in aluminum, to _Al 2 _{O 3} 1 mol to 0.3 mol and, preferably 0.02 to 0.2 mol. Alkaline earth metal has an effect of further enhancing cohesiveness due to a synergistic effect with a silicon compound, whereas _{Al 2} O _{31 mol is produced.} The effect of alkaline earth metal is saturated when it exceeds 0.3 mol with respect to 1 mol of _{Al 2} O _31.

Further, in the present invention, examples of the alkaline earth metal represented by E include beryllium, magnesium, calcium and barium, and magnesium and calcium are preferable.

Further, in the present invention, Cl in highly basic aluminum chloride is contained in an amount of 1.0 to 3.0 mol, preferably 2.0 to 3.0 mol, based on 1 mol of _{Al 2} O _31. This Cl is the sum of Cl bonded to Al and Cl bonded to an alkali metal. The higher the basicity, the less Cl is bound to Al and the more Cl is bound to the alkali metal.

Further, in the present invention, SO ₄ in highly basic aluminum chloride contains 0 to 0.35 mol, preferably 0.05 to 0.25 mol, of _{SO 4} with respect to 1 mol of Al ₂ O _31.

In the present invention, SO ₄ (sulfate root) can be omitted depending on the type of river. SO ₄ has the effect of increasing the cohesiveness, but has a negative effect on the effect of reducing residual Al, and when the purpose is to reduce residual Al, it is better to reduce it as much as possible.

In the present invention, alkaline earth metal, as described above, the synergistic effect with the silicon compound, it is possible to further increase the cohesive properties, especially for SO ₄ by cohesion river water required, magnesium, silicon _{Since it is possible to reduce the SO 4} content by combining with, it is preferable to use an alkaline earth metal and a silicon compound in combination.

The silicon compound is contained in highly basic aluminum chloride in an amount of 0.001 to 0.1 mol, preferably 0.01 to 0.05 mol, based on 1 mol _{of Al 2} O _{31 as silicon.}

Silicon enhances cohesiveness and is particularly effective for treated water at high turbidity. If it is less than 0.001 mol, no improvement in cohesiveness is observed, and if it exceeds 0.1 mol, the effect is saturated, which is not preferable.

The basicity of the highly basic aluminum chloride of the present invention is 80 % to 90 %, and the highly basic aluminum chloride of the present invention is possible.

The water treatment flocculant composition of the present invention, the high basic aluminum chloride in terms _{of Al} 2 _{O 3} in water 8% to 12% by weight, preferably comprises 10 wt% to 11 wt%, used The concentration can be changed as appropriate depending on the quality of river water and other sampled water.

In the water treatment coagulant composition of the present invention, various additives can be used, and the additive does not inhibit the agglutinating action and does not hinder the drinking of the treated water which has been agglutinated. For example, there is no particular limitation.

Specific examples of the additive include a polymer flocculant, sodium citrate, sodium gluconate and the like.

The coagulant composition for water treatment of the present invention can be used by adding and mixing highly basic aluminum chloride to water so as to have a predetermined concentration.

When the coagulant composition for water treatment of the present invention is used as a coagulant, the number of residual Al, E260 and fine particles in the treated water after the treatment is remarkably reduced.

The highly basic aluminum chloride of the present invention
(1) A _{first solution of basic aluminum chloride having an SO 4} content (SO ₄ / Al ₂ O ₃ (molar ratio)) of 0 to 0.1 and a basicity of 40% to 65% is reacted with an alkaline solution. The first step of forming an alumina gel and
(2) The alumina gel obtained in the first step has a SO ₄ content (SO ₄ / Al ₂ O ₃ (molar ratio)) of 0 to 0.1 and a basicity of 40% to 55%. The second step of adding and dissolving in the second aluminum solution at 40 ° C to 80 ° C, and
(3) In the third step, an alkali carbonate is added to the solution obtained in the second step to obtain a third solution of basic aluminum chloride having a basicity of 80 % to 90%.
(4) The fourth step of aging the third solution obtained in the third step at 40 ° C. to 90 ° C. to obtain an aging solution, and
(5) Sulfate is added to the aging solution obtained in the fourth step to adjust the SO ₄ content in the aging solution to SO ₄ / Al ₂ O ₃ (molar ratio) = 0 to 0.35. It can be manufactured by going through five steps.

In the first step, _{a basic first solution of aluminum chloride having an SO 4} content (SO ₄ / Al ₂ O ₃ (molar ratio)) of 0 to 0.1 and a basicity of 40% to 65% was prepared as an alkaline solution. To produce an alumina gel.

The first solution of basic aluminum chloride used in this first step is not particularly limited, but usually has a basicity of 40% to 65%, and may be produced by a known method, for example, in an autoclave. It can be produced by reacting hydrochloric acid with aluminum hydroxide.

As an example, it is synthesized by reacting 35% hydrochloric acid: 649 g, aluminum hydroxide (moisture content 2.6%): 325.3 g, and water: 35.7 g in an autoclave at 160 ° C. for 160 minutes. Is.

Further, in the present invention, the alkaline solution of the raw material used in the first step may be an alkaline solution having a pH of 10 or more, for example, alkali metal hydroxide such as sodium hydroxide and potassium hydroxide, sodium aluminate, and the like. Examples thereof include a solution containing an aluminate alkali metal salt such as potassium aluminate. Alkali metal carbonates such as sodium carbonate and potassium carbonate can also be used.

Of these, when alkali metal hydroxide and alkali metal carbonate are used alone, the sodium content is high, and the basic aluminum chloride of the product inevitably contains a large amount of sodium chloride. Therefore, it is preferable to use it in combination with an alkali metal aluminate salt.

In alkali metal aluminate salts such as sodium aluminate and potassium aluminate, the alumina content contributes to the improvement of basicity, reduces the amount of Na required to achieve a predetermined basicity, and reduces the amount of residual sodium chloride due to the reaction. It is preferable because it can be reduced. Further, an alkali metal of alkali aluminate and Al ₂ O ₃ molar ratio of 1.0 to 2.0 can be used.

In addition to the alkali metal, the basic aluminum chloride contains 0 to 0.3 mol, particularly preferably 0.02 to 0.2 mol _{, of alkaline earth metal with respect to 1 mol of Al 2} O _31.

Further, this basic aluminum chloride contains 1.0 to 3.0 mol, particularly preferably 2.0 to 3.0 mol, of _{Cl with respect to 1 mol of Al 2} O _31. This Cl is the sum of Cl bonded to Al and Cl bonded to an alkali metal. Even if it is less than 1.0 mol or more than 3.0 mol, the stability of basic aluminum chloride deteriorates, which is not preferable.

Further, this basic aluminum chloride contains 0 to 0.26 mol of _{SO 4} with respect to 1 mol of _{Al 2} O _31. This SO ₄ is used as a supplement to cohesiveness and can be omitted depending on the type of water.

As a method of containing an alkaline earth metal such as Mg in basic aluminum chloride, a method of mixing and dissolving with magnesium chloride or the like in a first solution of basic aluminum chloride in the first step, and a method of mixing and dissolving basic aluminum chloride as a raw material in the second step. A method of mixing and dissolving as magnesium chloride or the like in the second solution can be mentioned.

SO ₄ in order to incorporate the is a method of mixing and dissolving the like SO ₄ Compound basic aluminum chloride first solution of the material in the first step, SO ₄ compound to a basic aluminum chloride the second solution of the material in the second step include a method of mixing and dissolving the like, to the solution obtained in the second step may be added SO ₄ compound.

The SO ₄ compound, aluminum sulfate, alkali metal sulfates, alkaline earth metal sulfates, be mentioned include sulfuric acid, Among them, aluminum sulfate, sodium sulfate, magnesium sulfate is preferred.

It must be noted here, if it contains SO ₄ basic aluminum chloride solution (first solution), the concentration of the SO ₄ is _Al 2 _{O 3} 1 mol at 0 to 0.1 mole There must be. If it exceeds 0.1 mol, it is not preferable because it thickens in the third and subsequent steps, easily gels, and easily solidifies.

When forming an alumina gel, the first solution is added to the alkaline solution having a pH of 10 or more and reacted. In the initial state of alumina gel formation, the alumina gel precipitated by adding the acidic basic aluminum chloride primary solution to the strong alkaline solution is rapidly dissolved in the alkaline solution.

As the reaction proceeds, the alkaline solution in which the alumina gel is dissolved becomes hypersaturated and precipitates the alumina gel. By mixing in a reaction solution having a pH of 10 or higher to prepare the alumina gel, the precipitated alumina gel becomes an acid. It does not grow into a poorly soluble crystalline alumina gel and becomes an easily soluble alumina gel.

Further, by maintaining the temperature at the time of mixing the alkaline solution and the basic aluminum chloride first solution at 0 to 40 ° C., an alumina gel can be stably produced even in an alkaline environment. Further, it is preferable that the produced alumina gel is aged before moving to the second step.

This aging further facilitates dissolution in the second step. The temperature at the time of aging is also preferably 0 ° C. to 40 ° C. If the temperature during mixing and aging exceeds 40 ° C., the alumina gel is polymerized too much, and the finished basic aluminum chloride becomes translucent, white and turbid, which is not preferable. The aging time is preferably about 0 to 2 hours.

In the second step, the alumina gel obtained in the first step _{is a base having an SO 4} content (SO ₄ / Al ₂ O ₃ (molar ratio)) of 0 to 0.1 and a basicity of 40% to 55%. It is added to a second solution of aluminium chloride at 40 ° C to 80 ° C and dissolved. In this case, the second solution may be added to the alumina gel solution.

As the second solution, one produced in the same manner as the basic aluminum chloride first solution used in the first step can be used.

Further, the dissolution liquid obtained in the second step is preferably subjected to a heating treatment at 50 ° C. to 90 ° C. at the time of dissolution and / or after dissolution. The processing time is 1 to 3 hours. By this treatment, undissolved alumina gel can be reduced, basic aluminum chloride can be stabilized, and precipitation and sedimentation during storage can be prevented.

_{When SO 4} is contained in this basic aluminum chloride solution (second solution), _{the concentration of this SO 4} is 0 to 0.1 mol with respect to 1 mol of _{Al 2} O ₃₁ as in the first solution. Must be. If it exceeds 0.1 mol, the dissolved alumina gel tends to gel again and solidify, which is not preferable. This tendency is remarkable especially when the basicity is high.

In the third step, an alkali carbonate such as sodium carbonate or potassium carbonate is added to the solution obtained in the second step to obtain a basic aluminum chloride third solution having a basicity of 80 % to 90%.

In the fourth step, the basic aluminum chloride third solution is aged for about 2 hours while maintaining the temperature of 50 ° C. to 80 ° C. As a result, a stabilized aged solution of highly basic aluminum chloride having a basicity of 80 % to 90% can be obtained.

Then, the aging solution, by adding sulfate by SO ₄ content is adjusted to be 0 to 0.35, it is possible to produce a highly basic aluminum chloride of the present invention.
If the SO ₄ content is less than the above range, the required amount (if the first and second solutions _{contain a part of SO 4} , the required amount minus the required amount) is used. Add to make highly basic aluminum chloride. When magnesium is included, it is preferable to add magnesium chloride to any of the steps as described above.

As the sulfate, a sulfate band, sodium sulfate, magnesium sulfate and the like can be used.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to such Examples.

Example 1
Sodium aluminate solution _(Al 2 _{O 3} in terms of 19.7%, Na ₂ O in terms of 20.2%) 109.0 g and sodium silicate solution (SiO ₂ conversion 28%, Na ₂ O in terms of 10%) 7.0 g Was mixed.

126.7 g of a basic aluminum chloride solution (basicity 49.7%, Al ₂ O ₃ concentration 19.1%, SO ₄ concentration 0%) was mixed with this to produce an alumina gel. Then, this alumina gel is aged at room temperature for 0.25 to 2 hours, and further, 281.1 g of a basic aluminum chloride solution (basicity 49.7%, Al ₂ O ₃ concentration 19.1%, SO ₄ concentration 0%). Was added and dissolved.

This solution was aged at 40 ° C. to 80 ° C. for 60 to 180 minutes, and 28.4 g of sodium carbonate was added to increase the basicity. Further, this basic aluminum chloride solution was aged at 40 ° C. to 90 ° C. for 60 to 240 minutes.

Then, 30.8 g of a liquid sulfuric acid band (Al ₂ O ₃ 8.0%, SO ₄ 22.3%) and 12 g of magnesium chloride hexahydrate were added, and finally, high basicity with a basicity of 80.5%. An aluminum chloride solution (Al ₂ O ₃ 10.3%) was obtained.

The composition of the obtained highly basic aluminum chloride is Si / Al ₂ O ₃ (molar ratio) = 0.03, Na / Al ₂ O ₃ (molar ratio) = 1.3, Mg / Al ₂ O ₃ (molar ratio). Ratio) = 0.06, Cl / Al ₂ O ₃ (molar ratio) = 2.7, SO ₄ / Al ₂ O ₃ (molar ratio) = 0.07, and the obtained highly basic aluminum chloride was There was almost no thickening and the storage stability was very good.

The performance of this highly basic aluminum chloride as a flocculant was evaluated using river water under the following test conditions. The composition is shown in Table 1 and the results are shown in Table 2.

<Test conditions>
Put 1 liter of river water in a beaker, add highly basic aluminum chloride with rapid stirring (100 rpm: 64 cm / sec), and then continue with rapid stirring (60 rpm; 38 cm / sec) for 1 minute under the same conditions as above. Perform for 10 minutes, allow to stand for 10 minutes, collect the supernatant with a siphon, turbidity, residual aluminum concentration, E260 (ultraviolet absorbance: trihalomethane removal rate). , The number of fine particles was calculated.

Further, the highly basic aluminum chloride was stored in a water bath at 50 ° C., and the storage stability was visually confirmed.

<Measurement method>
Turbidity: The supernatant was used as a sample and measured using a turbidity meter (WA-6000, manufactured by Nippon Denshoku Industries Co., Ltd.).

Residual aluminum concentration: Using the supernatant as a sample, the filtrate filtered using a 0.5 μm filter paper (GC-90 manufactured by Advantech Toyo Co., Ltd.) was measured by ICP emission spectroscopy. As the ICP emission spectroscopic analyzer, ICP-OES and SPS5000 manufactured by VARIAN were used.

E260: Using the supernatant as a sample, a filtrate filtered using a 0.5 μm filter paper (GC-90 manufactured by Advantech Toyo Co., Ltd.) is used as a spectrophotometer (Shimadzu Co., Ltd.) using a quartz glass cell with an optical path length of 1 cm. The absorbance at a wavelength of 260 nm was measured at a UV-2400 PC factory.

Number of fine particles: Measured using a high-sensitivity turbidity meter (NP-6000T manufactured by Nippon Denshoku Industries Co., Ltd.).

<Evaluation>
The turbidity was evaluated by the measured value. Storage stability was evaluated visually by storing in a water bath at 50 ° C. The residual aluminum concentration, E260 and the number of fine particles were evaluated by measured values.

Example 2
Highly basic aluminum chloride was obtained in the same manner as in Example 1 except that the sodium silicate solution of Example 1, magnesium chloride hexahydrate and liquid sulfate band were not added. The composition is shown in Table 1. Moreover, the test was performed and evaluated in the same manner as in Example 1. The results are shown in Table 2.

Example 3
Highly basic aluminum chloride having a basicity of 90% was obtained in the same manner as in Example 1 except that 60.6 g of sodium carbonate in Example 1 was added. The composition is shown in Table 1. Moreover, the test was performed and evaluated in the same manner as in Example 1. The results are shown in Table 2.

Example 4
In the fifth step of Example 3, high-basic aluminum chloride was obtained in the same manner as in Example 3 except that 26.6 g of sodium sulfate was added in order to add the _{shortage of SO 4.} The composition is shown in Table 1. Moreover, the test was performed and evaluated in the same manner as in Example 1. The results are shown in Table 2.

Reference example 1
Highly basic aluminum chloride having a basicity of 75.5% was obtained in the same manner as in Example 1 except that 14.5 g of sodium carbonate of Example 1 was added. The composition is shown in Table 1. Moreover, the test was performed and evaluated in the same manner as in Example 1. The results are shown in Table 2.

Reference example 2
Sodium aluminate solution (19.7% in terms of Al2O3, 20.2% in terms of Na2O) 110.7 g and basic aluminum chloride solution (basicity 49.7%, Al2O3 concentration 19.1%, SO4 concentration 0%) 128 .7 g was mixed to produce an alumina gel. Then, this alumina gel is aged at room temperature for 0.25 to 2 hours, and 273.8 g of a basic aluminum chloride solution (basicity 49.7%, Al2O3 concentration 19.1%, SO4 concentration 0%) is added and dissolved. did. This solution was aged at 40 ° C. to 80 ° C. for 60 to 180 minutes, and 14.5 g of sodium carbonate was added to increase the basicity.

Further, this basic aluminum chloride solution was aged at 40 ° C. to 90 ° C. for 60 to 240 minutes. Then, 39.7 g of a liquid sulfate band (Al ₂ O ₃ 8.0%, SO ₄ 22.3%) was added, and finally a highly basic aluminum chloride solution (Al ₂ O _{3) having a basicity of 75.5% was added.} 10.2%) was obtained. Moreover, the test was performed and evaluated in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 1
Instead of the highly basic aluminum chloride of Example 1, a commercially available (manufactured by Asahi Chemical Co., Ltd.) PAC (Al ₂ O ₃ : 10.3%, basicity: 52%, SO ₄ : 2.6% (SO) ₄ / Al ₂ O ₃ (molar ratio) = 0.27) was evaluated in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 2
Sodium aluminate solution _(Al 2 _{O 3} in terms of 19.7%, Na ₂ O in terms of 20.2%) 109.0 g and sodium silicate solution (SiO ₂ conversion 28%, Na ₂ O in terms of 10%) 7.0 g Was mixed.

231.4 g of a basic aluminum chloride solution (basic aluminum chloride, basicity 52%, Al ₂ O ₃ 10.3%, SO ₄ 2.6%, Cl 11.4%) was mixed with this to produce an alumina gel. did.

Then, this alumina gel was aged at room temperature for 0.25 to 2 hours, and further, 290.9 g of a basic aluminum chloride solution (basicity 49.7%, Al ₂ O ₃ 19.1%), a liquid sulfuric acid band (Al _2). 5.3 g of O ₃ 8.0%, SO ₄ 22.3%) and 12 g of magnesium chloride hexahydrate were added and dissolved.

This solution was aged at 30 ° C. to 50 ° C. for 90 minutes, and a highly basic aluminum chloride solution (Al ₂ O ₃ 10.3%) having a basicity of 71% was evaluated in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 3
45.5 g of metallic aluminum pieces were dissolved in 94.6 g of hydrochloric acid (35.6%) to obtain 402.4 g of a basic aluminum chloride solution (basicity 83.3%, Al ₂ O ₃ 23.1%). ..

To this, 112.1 g of a liquid sulfate band was added and mixed. Then, 13.0 g of sodium carbonate was added, and it was dissolved and aged at 80 ° C. for 120 minutes to obtain a basic aluminum chloride solution.

The composition of the obtained highly basic aluminum chloride was Na / Al ₂ O ₃ (molar ratio) = 0.3, Cl / Al ₂ O ₃ (molar ratio) = 0.9, SO ₄ / Al ₂ O ₃ (molar ratio). (Mole ratio) = 0.26. The composition is shown in Table 1, but the stability at 50 ° C. was poor, and the turbidity in the evaluation was 1 or more, so that it could not be used.

Comparative Example 4
Highly basic aluminum chloride having a basicity of 73.5% was obtained in the same manner as in Example 2 except that 7 g of sodium carbonate was added before the addition of the liquid sulfate band of Comparative Example 2 to set the aging temperature to 65 ° C. Obtained. This solution was evaluated in the same manner as in Example 1. The results are shown in Table 2.

Claims (3)

The composition is M / Al ₂ O ₃ (molar ratio) = 0.8 to 2.2 (M indicates the number of moles of alkali metal), E / Al ₂ O ₃ (molar ratio) = 0 to 0.3 (molar ratio). E indicates the number of moles of alkaline earth metal), Cl / Al ₂ O ₃ (molar ratio) = 1.0 to 3.0, SO ₄ / Al ₂ O ₃ (molar ratio) = 0 to 0.26. A highly basic aluminum chloride having a basicity of 80 % to 90%. The highly basic aluminum chloride according to claim 1, further comprising a Si compound of Si / Al ₂ O ₃ (molar ratio) = 0.001 to 0.1. A water treatment flocculant composition comprising the highly basic aluminum chloride according to claim 1 or 2 in water in an amount of 8% by weight to 12% by weight in terms of _{Al 2} O _3.