JPS5914244B2 - Precursor for flocculant, method for producing the same, and flocculant using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel flocculant precursor comprising an amorphous carbonate radical-containing aluminum/iron hydroxide, and a flocculant produced using this precursor.

The invention further relates to a method for producing a precursor for a flocculant.

Basic aluminum chloride salts are useful as flocculants,
Many proposals have been made regarding its manufacturing method.

A typical method is to dissolve aluminum hydroxide in hydrochloric acid, but ordinary aluminum hydroxide is generally difficult to dissolve in hydrochloric acid, and even if it dissolves in hydrochloric acid, the basic aluminum chloride salt solution produced is stable. The disadvantage is that it is lacking in

It has already been proposed to use a basic salt of iron-containing aluminum in liquid form as a flocculant instead of basic aluminum chloride. It has been disclosed that a basic salt in the form of a solution is produced by adding and reacting an alkaline substance such as calcium carbonate, sodium carbonate, or caustic soda to an aqueous solution of a substance.

Although this invention has great significance as it provides a liquid flocculant made of a basic salt of iron-containing aluminum, there are still some problems that need to be improved.

First, this liquid flocculant has a problem in that it contains a large amount of contaminant salts due to the use of the above-mentioned neutralization means.

Furthermore, in this method of producing a liquid flocculant, it is difficult to increase the concentration of the active ingredient, ie, the iron-containing aluminum basic salt.

Furthermore, this liquid flocculant has a pH in a low range of 1.2 to 1.6, and when used as a flocculant, it not only requires an alkali but also has the undesirable effect of corroding containers and the like.

Generally, the pH of a basic salt is not recognized to be related to the degree of polymerization of the basic salt, and there is also the problem that basic salts with such a low pH generally have a low aggregation effect.

The present inventors prepared a soluble aluminum salt and a soluble iron salt at a certain composition ratio in an aqueous medium containing an alkali carbonate, so that the pH was within a certain range depending on the mixing ratio of the iron salt. When the amorphous carbonate radical-containing aluminum/iron hydroxide is easily dissolved in hydrochloric acid with extremely little amount of contaminant salts, and this amorphous carbonate radical-containing aluminum/iron hydroxide is simply dissolved in hydrochloric acid. Not only does it have excellent solubility, but it does not lose its excellent solubility even when left for a long period of time. By dissolving the flocculant on site and supplying it in liquid form, transportation costs can be significantly reduced.Furthermore, we have discovered that this flocculant has outstanding flocculation performance, and have arrived at the present invention. .

According to the present invention, expressed in molar ratio on an oxide basis, [C02].

1. A flocculation characterized by being composed of amorphous carbonate radical-containing aluminum/iron hydroxide having a composition of [R2O3]-[Fe2O3]-0.01 to 0.88 [R2O3] and being easily soluble in hydrochloric acid. A precursor for the agent is provided.

According to the present invention, furthermore, expressed in molar ratio on an oxide basis, [CO2]≧o2□ [R2O3 [F・203]=o, o□~.

, 88[R2O3] Consisting of a solution of amorphous carbonate-containing aluminum/iron hydroxide dissolved in hydrochloric acid or hydrochloric acid-sulfuric acid,
The solution has the following formula % formula % where:
[R2O3] represents basicity defined as ×100, where X is CFe2O
3), a basicity that satisfies [R2O3], a pH of 2.5 to 3.5, and an Al2
A liquid flocculant is provided, characterized in that it has a concentration, expressed as the total amount of O3 and F e 203, of between 5 and 30 by weight.

According to the invention, soluble aluminum salts and soluble iron salts (
III) in an aqueous medium containing alkali carbonate such that the molar ratio of sound is 0.01 to 0.88 and the pH is 6.5-0.7X to 9.8.
-1.1. Amorphous [
R2O3] A method for producing a precursor for a flocculant is provided, which is characterized by producing a carbonate radical-containing aluminum hydroxide.

In the present invention, the soluble aluminum salts used are mineral acid salts of aluminum, such as sulfates, nitrates, chlorides, etc., especially sulfates, or alkali aluminates.

As the soluble iron salt [■], trivalent iron mineral acid salts such as sulfates, nitrates, chlorides, etc., especially sulfates are used.

These raw materials may be prepared by mixing an aluminum salt and an iron salt and subjected to the neutralization reaction described below, but they may also be prepared all at once.

For example, montmorillonite clay minerals such as acid clay or other clay minerals such as calcined kaolin contain alumina and iron in addition to silica, so by extracting them with sulfuric acid, aluminum sulfate A raw material solution containing iron sulfate and iron sulfate can be easily obtained.

Of course, an aluminum raw material or an iron raw material may be added to this extract in order to adjust the composition ratio of both raw materials.

Further, even if these raw materials contain divalent iron salts in addition to trivalent iron salts, they are equivalent because they are oxidized in the neutralization step.

Such a raw material solution can also be easily obtained by extracting red mud, which is a by-product of the Bayer process, with sulfuric acid instead of clay minerals.

Further, an alkaline aluminate solution used as an aluminum raw material is produced by extracting an alumina raw material such as bauxite by the Bayer method or the method described in JP-A-54-107900.

Soluble aluminum salts can be used alone or in combination of two or more, for example, a combination of aluminum sulfate solution and sodium aluminate can be used, as detailed later.

In the present invention, the above-mentioned soluble aluminum salt and soluble iron salt (III) are mixed in an aqueous medium containing an alkali carbonate to give a ["e203]0')-E-JIi ratio □Qf)So,
01 to 0.88 (!: [R2O3] and the pH is 6.5-0.7X to 9.8-
1.1. Neutralization to obtain X is extremely important in producing an amorphous carbonate radical-containing aluminum hydroxide that is easily soluble in hydrochloric acid.

When the soluble aluminum salt and iron salt are mineral salts, this neutralization can be carried out using an alkali. , for example, alkali hydroxide,
Combinations with alkali aluminates may also be used.

Further, when the raw material aluminum salt is an alkali aluminate, neutralization may be performed using an iron salt together with mineral acids such as hydrochloric acid and sulfuric acid, if necessary.

In addition, as mentioned above, it should be understood that iron sulfate and an alkali aluminate may be mixed to perform neutralization by double decomposition.

Setting the above-mentioned molar fraction to 0.01 or more, especially 0.1 or more makes the produced floc heavy and dense with less water retention when used as a flocculant. On the other hand, from the viewpoint of stability as a liquid flocculant, it is important to keep the molar ratio X at most 0.88, particularly at most 0.62.

Furthermore, this neutralization reaction was carried out in an aqueous medium containing an alkali carbonate and in the above-mentioned 6,5-0.7X to 9.8-1. I
Working at a pH of X is extremely important in obtaining the amorphous carbonate flocculant precursor.

That is, under conditions where the pH is lower than 6-0.7X or when the pH is lower than 9.
8-1. When neutralization is carried out under conditions higher than IX, even if the aqueous medium contains alkali carbonate, the generated aluminum/iron hydroxide contains Al2O3 and Fe203.
It is difficult to contain 0.1 mol or more of carbonate radicals per 1 mol of the total amount.

Furthermore, aluminum/iron hydroxides with carbonate radical content lower than the range specified in the present invention have lower solubility in hydrochloric acid than the amorphous carbonate precursor according to the present invention, and furthermore, this solubility changes over time. The downward trend is also significant.

In the amorphous carbonate precursor according to the present invention, the carbonate radicals appear to be bonded to the aluminum/iron hydroxide in a manner different from that of the original alkali carbonate.

In other words, this fact shows that even when an amorphous carbonate precursor is repeatedly washed, the carbonate radicals hardly decrease, or even if they do, only the carbonate radicals corresponding to the attached sodium carbonate content decrease. It is confirmed by doing.

The amount of carbonate radicals contained in the amorphous carbonate precursor varies depending on the pH at the time of neutralization, and this pH is further influenced by the molar fraction of iron contained.

That is, when neutralized at pH 8,5-X, the intermediate contains the most carbonate radicals, and from this value, pH 6,5-0,7
It is observed that as the pH moves towards the X side or pH 9,8-1, IX side, the content of carbonate radicals decreases.

As a method for producing basic chlorides similar to the present invention,
Publication No. 38121 discloses that an alkaline aluminate solution is circulated and sprayed into a carbon dioxide gas stream to cause a rapid reaction, and the precipitated fine aluminum hydroxide is dissolved in an acid solution to form a basic aluminum salt. There is.

In this method as well, alkali carbonate is certainly formed in the solution, and the aluminum hydroxide produced also contains carbonate radicals, but in this method, as the pH of the solution drops to about 10.2, However, it is difficult to adjust the pH to a range of 6.5-0.7X to 9.8-1.1X.

In addition, the aluminum hydroxide produced is 0 per Al2O3.
．． It only has less than 1 mole of carbonate radicals.

Thus, it will be understood that the aluminum hydroxide formed by this method has undergone considerable polymerization and still has problems to be improved in terms of its solubility and its tendency to decrease over time.

On the other hand, according to the present invention, the iron content molar fraction X
Also related to neutralization from pH 6,5-0,7X to 9,8-
1.1. By carrying out the process within the range of This was successful in eliminating the decline.

Figure 1 of the attached drawings is a diagram showing the relationship between the pH at the time of neutralization and the concentration of carbonate groups in aluminum/iron hydroxide containing amorphous carbonate groups, and the pH at the time of neutralization is critical to the concentration of carbonate groups. It is clear that this will have a significant impact.

In the neutralization step of the present invention, the amount of alkali carbonate added to the aqueous medium is at least an amount commensurate with the carbonate radicals to be contained in the amorphous carbonate precursor, and generally the amount It is preferable to use Na2CO3 in an amount of 0.1 mol or less, particularly 0.2 to 2 mol, per 1 mol of Na2CO3 in total with Fe2O3.

On the other hand, raw material aluminum salt and iron salt are Al2O3+
Fe2O3 is preferably used in a concentration of 1 to 80 g/f, especially 10 to 50 g/l, in the reaction medium.

Although room temperature is sufficient for neutralization, the reaction may be carried out with heating if desired.

However, in a reaction at a high temperature, carbon dioxide gas may escape out of the reaction system, so the temperature should be kept at 80° C. or lower.

Mixing during the neutralization reaction also requires consideration to prevent carbon dioxide from escaping.

Thus, there are methods in which an alkaline substance is first filled into the reactor, and then an acidic substance is added thereto while stirring;
Alternatively, a method may be adopted in which an acidic substance and an alkaline substance are simultaneously added into an aqueous medium having a pH within the above-mentioned pH range and stirred.

Thus, an amorphous carbonate intermediate precipitates.

This is filtered and, if necessary, washed with water to remove contaminant salts to obtain a precursor to be added to the next hydrochloric acid dissolution step.

The amorphous carbonate precursor according to the present invention has outstanding solubility in hydrochloric acid, and the solubility of this intermediate does not decrease even when stored for a long period of time.

This intermediate can thus be supplied to the end use site in solid form for convenient transportation, where it can be dissolved and used as a flocculant, etc.

In this dissolution step, the amorphous carbonate precursor is dissolved in hydrochloric acid or a mixed acid of hydrochloric acid and sulfuric acid to obtain the following formula (%)), where Y is the formula [□-(C1)+2 (80,) ]C
6 [R2O3] x 100, X represents the molar fraction of ([R2O3]), more preferably (1) X≧0.01 ( 21,7≦¥≦84〕(2)
¥≧72X+21 (0,01≦X≦0.62) (3)
¥≦84 [0,01≦X≦0.62) (4)X≦0
．． Basicity satisfying 62, pH of 2.5 to 3.5, and Al
Expressed as the total amount of 2O3 and Fe2O3, q is 5 to 3
An aqueous solution of basic aluminum iron chloride having a concentration of 0% by weight is formed.

Figure 2 is a diagram plotting the stability of this liquid flocculant with basicity (maximum) on the vertical axis and iron molar fraction ■ on the horizontal axis, and Figure 3 shows the same vertical axis and horizontal axis. FIG. 2 is a diagram plotting the state of floc formation when used as a flocculant.

Note that straight lines 1, 2° 3, and 4 in the figure are straight lines corresponding to the equations in which there is an equal sign in the above-mentioned equations.

Referring to these figures 2 and 3, basicity (Y)
It can be seen that by adjusting the iron mole fraction and the iron mole fraction within the ranges specified in the present invention, an extremely good combination of stability and flocculation effect is achieved.

In addition, the flocculants according to the present invention have a pH 1 pH 1 of conventional basic aluminum iron chloride flocculants in connection with being derived from the above-mentioned unique amorphous carbonate precursors.
, 2 to 1.6, it has the surprising feature of having a considerably higher pH of 2.5 to 3.5.

As already mentioned above, the pH of basic chloride decreases as the degree of polymerization increases, but the fact that the flocculant according to the present invention exhibits such a high pH means that the degree of polymerization of this flocculant is higher than that of conventional flocculants. This suggests that the storage stability is extremely low compared to that of the other products, and this also correlates well with the fact that the storage stability is extremely low and the flocculation performance is excellent.

Furthermore, this liquid flocculant has a significantly higher concentration of 5 to 30 g, which provides significant advantages in terms of transportation and storage costs.

In addition, the molar ratio of [803] in this basic salt is 0 [R2O
3] to 0.65, preferably in the range of 0.2 to 0.4.

This liquid flocculant can be used in end applications in high concentrations of 10 to 30 parts by weight, and can also be used in similar applications in dilute concentrations of 0,01 to 10 parts by weight.

The present invention will be explained in more detail below with reference to Examples.

In addition, the component measurement method and agglutination test method (jar test method) in Examples are as follows.

(1) Component Measuring Method Among the components, Al2O3 and Fe2O3 were measured by a general chelate titration method, and the CO2 content was measured by a Schletter alkaline meter.

(2) Agglutination test method (jar test method) Test water (raw water) 500rrll or 1,000yd (
When diluting and injecting the sample flocculant stock solution, use 50% test water.
When injecting 0Hiro stock solution as it is, use 1,000r of test water.
Ill), and each sample solution [flocculant stock solution or diluted solution (
A1203 diluted to a concentration of 0.15 (w/v) %) was injected in a tonal amount of 3.14 ppIn as Al2O3, and stirred rapidly (120 rl) for 3 minutes and slowly stirred (60 rpm for 10 minutes). After this, the size of the flocs produced was observed with the naked eye, and after being allowed to stand still for another 10 minutes, the supernatant liquid was taken from a portion approximately 2 cIIL below the water surface.
Measure turbidity and pH.

The size of flocs was displayed according to the following standards.

Figure 3 Display of agglutination ability Adult 1 day later ◎ (4)) SO, o,: 3”°’ dog
3~5w1 ■ ・ / R203-mol medium
2-3M Mouth size: around 1 µm ◇ Very small: 0.5 M or less △ Example 1 2.221 g of aluminum sulfate (18 hydrate, reagent grade) and 1,665 g of ferric sulfate (reagent grade) were dissolved in water. and sodium carbonate (reagent grade)
23=H' and sodium hydroxide (reagent grade) 1.07
A solution obtained by dissolving 9g in water to make 4.091 was poured into a reaction vessel previously filled with 6.827g of water at the same speed while stirring, and continued stirring even after the addition was completed.
The aging reaction is carried out for 30 minutes.

The pH after the reaction was 8.2. When filtered and washed with water, Al2O3: 7.11%, Fe2O3: 15.5
9%, Na2O”, 0.03%, CO2: 2.6
5% (CO□ content relative to R2O31MoiLy: 0.
2.50 Or of carbonate radical-containing aluminum/iron hydroxide containing 360 mol) was obtained.

Next, in another container, add 35% hydrochloric acid 8631, water 1, O'0
Add 0yd, add the entire amount of this cake and stir gently, and it will immediately start to melt while generating bubbles and heat. When heated further, it will completely melt at 40℃ and turn dark brown.
Basic aluminum chloride/iron aqueous solution 4 with the following composition:
300 f was obtained.

Composition of basic aluminum chloride/iron: Alo, 52Fet, 1s(OH)4. o3clt97
Basicity: 67% R2O3 concentration of aqueous solution: 13.69 pH: 2.9 The carbonate radical-containing aluminum/iron hydroxide (flocculant precursor) obtained in this example has extremely excellent solubility in hydrochloric acid. Furthermore, the stability of the obtained basic aluminum chloride/iron aqueous solution during long-term storage (6 months or more) was also extremely high.

Table 1 shows the performance test results of the basic aluminum chloride/iron aqueous solution obtained in this example as a flocculant.

Example 2 Sodium aluminate (A!’20318.69%.

Na2017.96%) 13.72y and sodium carbonate (reagent grade) 234S' dissolved in water to form 4.091 and ferric chloride (large water salt, reagent grade) 1.07O
A solution obtained by dissolving f in water to make 4.09 t was added at the same speed while stirring into a reaction vessel in which 6.82 t of water had been previously charged, and after the addition was finished, stirring was continued.
The pH after three reactions in which the aging reaction was carried out for 0 minutes was 9.3.

When this is filtered and washed with water, Al2O3 near, 22%
v Fe2O3”, 8.56%.

Na2O: 0.83% = C1,” 0.26
%, CO2'', coefficient 2.34 (CO□ content: 0.427 mol relative to R2031 mol), 3,500 f of carbonate-containing aluminum/iron hydroxide was obtained.

Next, put 963 g of 35% hydrochloric acid in another container, add the entire amount of this cake, and stir gently. Melting begins immediately while generating bubbles and heat. The temperature rises to about 40°C due to the heat of reaction, and the cake completely dissolves to form a dark brown solution.

Further, the mixture was concentrated by heating to 80 to 85° C. while stirring, to obtain 2,800 P of an aluminum chloride/iron aqueous solution having the following composition.

Composition formula of basic aluminum/iron chloride: % Formula %: 69 The carbonate radical-containing aluminum/iron hydroxide (precursor for flocculant) obtained in this example has extremely excellent solubility in hydrochloric acid. The stability of the basic aluminum chloride/iron aqueous solution during long-term storage (6 months or more) was also extremely high.

Table 1 shows the performance test results of the basic aluminum chloride/iron aqueous solution obtained in this example as a flocculant.

Example 3 Sodium aluminate (Al2O3 18,69%, Na2
017.96) 1,426f and sodium carbonate (reagent grade) 234S' dissolved in water to form 4.09A, ferric sulfate (reagent grade) 659f and acidic industrial waste liquid (components: Al2O34,48%, Fe2030
．． 96%, 5O319, Section 25) Dissolve 1,629S' in water to make 4.091 and pre-mix 6.8% of water.
At the same time, the mixture was poured into the reaction vessel containing No. 21 at the same speed while stirring, and even after the addition was finished, stirring was continued to carry out the aging reaction for 30 minutes.

The pH after the reaction was 9.6.

When this is filtered and washed with water, Al2O3: 8.94%,
Fe2O3: 4.77%, SO3: 0.90%.

CO2: 1.93 ratio (CO□ per 1 mole of R203
3,700 S' of carbonate radical-containing aluminum/iron hydroxide containing 0.373 mol) was obtained.

Next, put 1,057 L of 35th grade hydrochloric acid in another container. Add the entire amount of this cake and stir gently, it will immediately begin to melt while generating bubbles and heat, and will continue to melt until the temperature reaches 80 to 80.
When heated to 5°C, the cake soon completely dissolves and becomes dark brown, forming a basic aqueous solution of aluminum/iron chloride with the following composition: 4,700 ml was gotten.

Compositional formula of basic aluminum/iron chloride: % formula %): 66 R2O3 concentration in aqueous solution: 10.70 tt pH: 3.1 Carbonate radical-containing aluminum/iron hydroxide (flocculant) obtained in this example The solubility of the basic aluminum chloride/iron aqueous solution obtained was extremely high in terms of long-term storage (6 months or more).

Table 1 shows the performance test results of the basic aluminum chloride/iron aqueous solution obtained in this example as a flocculant.

Example 4 Alkaline industrial waste liquid (component: Na203.00%
Acidic industrial waste liquid (component: Al2O34, 38% t F
e2030.95 section, 80318.96 section) 3.31
3f was added with stirring, and the stirring was continued even after the addition was completed to carry out the aging reaction for 30 minutes.

The pH after the reaction was 7.6.

When this is filtered and washed with water, Al2O3: 10.38%
, Fe2O3", 1.72%, 804", 0
．． 1.80 Of of carbonate radical-containing aluminum/iron hydroxide containing CO□: 2.79□ (CO□ content: 0.563 mol relative to R2031 mol) was obtained.

Next, when adding 35% hydrochloric acid 8641 to a separate container and stirring gently, it immediately begins to dissolve while generating bubbles and heat.When further heated to 80-85℃, the cake completely dissolves in about 10 minutes. Dissolves and turns dark brown.

Furthermore, by continuing heating and stirring, water is evaporated and concentrated, and the total liquid volume is reduced to 1,146 SF.

To the resulting solution, 832 rn1. By adding the above-mentioned acidic industrial waste liquid 1791, a basic aluminum chloride/iron aqueous solution 2.15 with the following composition is obtained.
I got 7g.

Compositional formula of basic aluminum chloride/iron: % formula %) (30:62 R2O3 concentration of aqueous solution: 10.50 pH: 2.5 Carbonate radical-containing aluminum/iron hydroxide obtained in this example ( The flocculant precursor) had extremely excellent solubility in hydrochloric acid, and the obtained basic aluminum chloride/iron aqueous solution had extremely high stability during long-term storage (6 months or more).

Table 1 shows the performance test results of the basic aluminum chloride/iron aqueous solution obtained in this example as a flocculant.

The comparative examples listed in Table 1 are examples in which commercially available basic aluminum chloride (PAC) was used as a flocculant.

[Brief explanation of drawings]

Figure 1 shows the production pH (pH at neutralization) of amorphous carbonate radical-containing aluminum/iron hydroxide obtained by the present invention and C
It is a diagram showing the relationship between O2 content, with the vertical axis representing the CO2 content (CO2/R2O3 molar fraction) and the horizontal axis representing the field. In the figure, curves A, B, C, D, and E are F e203 /R2O3 of carbonate-containing aluminum/iron hydroxide, respectively.
Molar fraction is 0, 0.26, 0.59, 0.86
. It shows the relationship when it is 1. Figure 2 is a diagram plotting the stability of a basic aluminum chloride/iron solution, where the vertical axis is basicity Y (support) and the horizontal axis is iron mole fraction X (F e2 o3 / R20a mole fraction). It's great. In the figure, straight lines 1, 2, 3, and 4 indicate the boundaries between the stable region and the unstable region, and are expressed by the following formula. (1) X=0.01 (2) Y=72X+21 (3) Y284 (4) X=0.62 The stability of the basic aluminum chloride/iron solution was expressed as follows. Solution concentration: R203 10% or more, standing time = 6 months Figure 3 is a diagram in which the floc formation state of basic aluminum chloride/iron is plotted on the vertical and horizontal axes, exactly the same as in Figure 2. Figure 4 shows the production pH of aluminum/iron hydroxide containing easily soluble carbonate radicals (
It is a diagram showing the relationship between pH at neutralization) and iron mole fraction, with the vertical axis representing pH and the horizontal axis representing iron mole fraction (Fe2O3/R2O
3 mole fraction). In the figure, the dotted line indicates the relationship when the CO2 content (CO□/R2O3 molar fraction) is at its maximum, and the solid line a. b has a CO2 content of 0 on the acidic side and alkaline side, respectively.
．． It shows the relationship when it is 1. Figure 5 shows the iron mole fraction of carbonate radical-containing aluminum/iron hydroxide and CO obtained from the relationship shown in Figure 1.
□It is a diagram showing the relationship between the CO2 content when the content reaches its maximum, and the vertical axis shows the iron mole fraction (F e2 o3/
R203 mole fraction), and the horizontal axis shows the maximum CO2 content (CO
□/R2O3 molar fraction) is the best.

Claims (1)

[Claims] 1 [CO2]≧0.expressed in molar ratio on an oxide basis. □ [R2O3] [Fe2O3] -〇, 01 to 0.88 [R2O3] However, [R2O3] is the sum of molar concentration [Al2O3] and molar concentration CFe2O3), and all [R2O3] hereinafter express this meaning. A precursor for a flocculant, characterized in that it is composed of an amorphous carbonate radical-containing aluminum/iron hydroxide which has the following composition and is easily soluble in hydrochloric acid. 2 [CO2] expressed as a molar ratio on an oxide basis. 1. [R2O3]-[Fe2O3]-〇,01~0.88 [R2O3] Consists of a solution in which an amorphous carbonate radical-containing aluminum/iron hydroxide is dissolved in hydrochloric acid or hydrochloric acid or sulfuric acid,
The solution has the following formula % formula % where Y is the formula [1t((jll+z(803))]×6
[R2O3] represents basicity defined as 100, X is CFe2O3
) representing the molar fraction of [R2O3], a basicity of 2.5 to 3.5, and Al2
5 to 30 expressed as the total amount of O3 and Fe2O3
A liquid flocculant having a concentration by weight. 3 Soluble aluminum salt and soluble iron salt (III) in an aqueous medium containing an alkali carbonate ["e203
] CD%yv ratio CyO 0.01 to 0.88 [R2
O3] and... is 6.5-0.7 X to 9.8
-1, IX to produce an amorphous carbonate radical-containing aluminum iron hydroxide having a molar ratio (1) of [C02] of 0.1 or more [R2O3]. A method for producing a precursor for a flocculant.