DK172765B1 - Basic aluminum chlorosulfate, process for their preparation and use as flocculant - Google Patents

Abstract

A basic aluminium chlorosulphate whose basicity is between 45 and 70 % and in which more than 80 % of the SO4<2><-> ions are complexed. This product is prepared by reaction of calcium carbonate with an aluminium chlorosulphuric solution. This product can be used for coagulating and flocculating suspended matter in water, in particular with the aim of preparing potable water. An advantage of the product of the invention is that it leaves very little residual aluminium in the water produced.

Description

5 in DK 172765 B1

The present invention relates to a basic aluminum chlorosulfate, process for the preparation thereof and use thereof as a fumigant.

Treatment of waste streams, of house wastewater, of spring water or of river water, almost always includes a step for removing materials in suspension. Products known to have a coagulant effect on these 10 materials in suspension or in solution in the aqueous system to be treated are materials which will not decant within a reasonable time by natural decanting.

These products further convert these materials into coagulated lids which are easy to filter and to separate 15 from the liquid phase.

In French Patent Nos. 2 036 6B5, 2 226 361 and 2 534 897 such products and their use are mentioned.

In European Patent Application Serial No. 218,487, 20 discloses a product which may reduce the amount of aluminum remaining in the water after treatment.

Now a very effective chlorine sulphate has been found which can be used in a very simple way.

25

The chlorine sulphate according to the invention is a basic aluminum chlorine sulphate, which is in the form of an aqueous solution, which is characterized in that it comprises a product of the formula: A1, C1, "(OH) 3n *," Ι: -ιη -Γρ (SO.j) p X |; wherein: X represents an alkaline earth metal, preferably calcium, n, m, p and k represent molar concentrations (mol / l) of the components in solution less than 20% of the SO 2 ions are precipitated by reaction with barium chloride at room temperature and whose basicity: 3n + 2k - m - 2p is 10 3n between 45 and 70 ",

Advantageously, such products are selected according to the gross formula shown above, in which the ratio of aluminum equivalent to chlorine, i.e. 3 n / m is <2.8 preferably <2.75.

Although one could have a large basicity range, 20 usually use products with a basicity of between 50 and 70%. Depending on the uses of the product, different values for the basicity may be preferred. Especially in the preparation of drinking water, residues of aluminum have been observed, which is the lower the basicity.

The failure to precipitate with barium salts of the majority of the SCV ions in the product indicates that this sulfate is complex. The determination of the total content A of sulfate 30 contained in the product is carried out in the usual manner by precipitation of the sulfate with barium by means of a solution of barium chloride and of hydrochloric acid which is added to the sample which is heated to boiling. When the barium chloride is introduced at room temperature (i.e., between 15 and 25 ° C) in a non-acidic sample in stoichiometric amounts relative to the SO42 ions present in the product, the weight of the dry precipitate is the dry precipitate. , as formed after one hour, in relation to the content D of SOf 'ions, designated as "non-complex".

Difference A-B is termed "content of SO ^ 'ions that are complex".

The product of the invention, which is in the form of an aqueous solution containing between 5 and 15% by weight of 10 aluminum expressed as Δ1.0., Is mixed with barium chloride in aqueous solution (eg between 5 and 20 g / l). You homogenize and you let the sediment form through approx. One hour is filtered off on a filter crucible with the porous site number 4. All these treatments from the mixture of the chlorine sulfate with BaCl 2 until the filtration takes place at room temperature, ie. between 15 and 25 ° C.

The filtrate further contains the SOv, ions ions of the product of the invention, which are not precipitated in the form of BaSO1 and are thus complex. To find this 20 amount of complex SO / -, the product is decomposed by adding hydrochloric acid in the filtrate and subsequent heating to boiling. The SO 4 '' ions are then precipitated with Bad; in aqueous solution between 5 and 15% by weight *. Measurement of the mass of BaSO 1 in the precipitate, by comparison with the total amount of SO 2 Z 2 in the product, gives the percentage content of SO 2 ions which are precipitated by the reaction with barium chloride at room temperature.

Advantageously, the products have less than 10 6 SO 2 'ions which settle, under usual conditions, preferably <5 *, ie. at> 95? of SO. ^ - are complex.

The present invention also relates to a process for the manufacture of these products.

The method is characterized by the features of claim 7.

DK 172765 B1 4

The term alumina means any product of the type alumina or aluminum hydroxide. It is preferred to use alumina derived from the so-called Bayer process or aluminum hydroxides, which are by-products of aluminum surface treatments.

Advantageously, the alumina is attacked with a mixture of concentrated hydrochloric acid and concentrated sulfuric acid at a temperature between 70 and 115 ° C. This temperature range is not essential, it merely corresponds to a reaction time of 1-2 hours, which is in line with the industrial implementation of the process. One can place the alumina in a mixture of the acids or allow the alumina to react with one and then with the other acid, or one can add the acids several times. It is preferred to attack the alumina with a mixture of hydrochloric acid and sulfuric acid, whereupon, in part of the alumina already dissolved, a supplementary portion of concentrated sulfuric acid is added.

Advantageously, hydrochloric acid is used in a solution stronger than 20% by weight, preferably a 33% by weight solution. It is also advantageous to use sulfuric acid with at least 60% by weight. The amount of hydrochloric acid expressed in moles between 1.89 and 2.44 times the amount of alumina expressed as moles is Al 2 O, preferably between 1.95 and 2.40.

Similarly, the amount of sulfuric acid expressed in moles (used over one or more cycles) is between 1.37 and 1.73 times the amount of alumina expressed as moles of Al 2 O 1, preferably between 1.42 and 1.68.

The solution of the aluminum chlorine sulphate from step a) is then contacted with the alkaline earth metal compound. This DK 172765 B1 5 alkaline earth metal compound can e.g. be selected from calcium carbonate, hydroxide / oxide or hydrogen carbonate.

A mixture of these products can be used, e.g. of calcium carbonate and calcium hydroxide, 5 calcium carbonate is preferred.

The alkaline earth metal compound is advantageously present in finely divided form, such as in the form of a powder. Although capable of operating at any temperature, it is preferred to heat the aluminum chloride sulfate solution between 60 and 100 ° C to contact it with the alkaline earth metal compound.

This contact is generally carried out for 10 or 30 minutes, which corresponds to the usual technological conditions; but one does not exceed the scope of the invention by working for a few minutes or for a few hours.

The amount of alkaline earth metal compound expressed in moles is between 1.63 and 1.70 times the amount of the alumina introduced in step a), expressed in moles Al; Ch, preferably between 1.65 and 1.68. Once all the alkaline earth metal compound has been mixed with the solution of aluminum chloride sulphate, the mixture is allowed to stir. The temperature can be arbitrary, in general, the temperature settles at between 30 and 60 ° C.

This end of step b) advantageously lasts from 15 minutes to 2 hours. It is then sufficient to separate the alkaline earth metal sulfate. Conventional agents such as filtration, centrifugation can be used.

This separation preferably takes place above room temperature, e.g. between 30 and 60 AD.

The filtrate contains the basic chlorine sulfate of the invention in solution in water. The concentration can be modified by the addition of water. The product of the invention is in the form of this solution containing by weight between 5. and 15% aluminum expressed in the formula Al 2 O 2. This form has the advantage of having a stable (no solid phase appearance) for several months at room temperature.

The present invention also relates to the use of these products as coagulant and flocculant in the treatment of water, in particular for the purification of water for the preparation thereof of drinking water.

Among the basic aluminum chlorine sulphates according to the invention, those exhibiting at the same time: 15 have a basicity> 60% and whose weight ratio Cl / (total SO () is between 4.5 and 8 when used in the area 20 processes for aqueous media, a most optimal degree of treatment by flocculation, which is less than similar properties with respect to the aluminum remaining in solution (residue Al).

25

The following examples further illustrate the invention.

EXAMPLE 1: 30 Preparation of a Product of the Invention

Step a): A glass reactor containing 3 moles of HCl in the form of 331.9 g of a 33% solution and 1.45 moles of 78% H.SOi, 3.09 moles of a 99 "powder of Al (OH) is added. 35 is heated to 70 ° C, after which the temperature stabilizes at 102 ° C. It is diluted with 374 g of water, to which 1 mol of 78 µl of hydrochloric acid is added. The temperature rises to 112 ° C in 20 minutes. The duration of this step is approx. 2 hours.

Step b): Allow to cool to 93 ° C and introduce, within 30 minutes, 2.60 moles of CaCO 3, i.e. 481.5 g of a 54% slurry of CaCO 3. Allow the reactor to stir for 1 hour. hour and 30 minutes, and the temperature then becomes 61 ° C.

10

Step c): Allow to cool to 40 ° C, then filter in a vacuum filtration apparatus. Wash the lark cake with 100 g in water. The dry cake weighs 362 g and contains, by weight, 7.73% aluminum expressed as A1.0-, 15 53.4% SO / -, 1.35? Cl ', the remainder being calcium. 1100 g of filtrate are collected at a density of 1,224, which is diluted with 109 g in water. The product obtained in the form of a solution is obtained.

The solution weighs 1220 g, has a density of 1,201 and contains by weight 10.09% Al expressed as Al. 0 ·, 8.11% Cl ", 1.8% SO₂ -, 1.78% complex SO / - and 1.08% Ca77, i.e. the ratio (Al equivalent) / Cl is 2.6, 97.3- of SO / - are complex.

25

The basicity is 64.18% and the weight ratio Cl / (total SO, -) is 4.43.

EXAMPLE 2: 30

Preparation of another product according to the invention

One proceeds analogously to Example 1, but using other proportions of the reaction components.

The starting point is always 3.09 moles Al (OH) duration of DK 172765 B1. Step (a) is 2 hours. Step b) lasts for 2 hours and begins at 90 ° C.

Step a): 5

Final temperature: 113.4 "C

HCl: 3.0 mol 10 H; SO 2: 2.6 mol

Step b):

End temperature: 63 "C

CaCO 2: 2.6 moles in the form of a 4 4% liquid 20

After separation of the calcium sulfate (step c) and dilution with water, the following product is obtained, the percentages given being by weight in the solution.

25 Percentages in solution

AljOj: 10.59¾

Cl: 8.35¾30

Total SO42-: 2, 13%

Complex S042-: 2.13% Residue Ca: 0.77% DK 172765 B1 9 (Al equivalent) / Cl: 2.65

Basicity: 61.29 5 Complex SO 2 ions: 100, 00 ?.

Cl / (total SCV'-): 3.92 Example 3: 10

Preparation of another product according to the invention

One proceeds analogously to Example 1, but using other proportions of the reaction components.

The starting point is 3.09 mol Al (OH) .., the duration of step a) cr 2 hours. Step b) lasts 2 hours and begins at 90 ° C.

Step a):

Final temperature: 112 "C

HCl: 2.81 mol H; SO 4: 2, 25 mol 25

Step b):

Final temperature: 62 AD

CaCO 2: 2.38 moles in the form of a 54% liquid.

After separation of the calcium sulfate (step c) and dilution with water, the following product is obtained, with the 35 percent of the manufacturer being listed as the weight percent of the solution.

DK 172765 B1 10

Percentages in solution

Al.Oj: 9.96¾ 5 Cl: 7.72? ·

Total SO4, 2-: 1.50 o

Complex 50./-: 1.50 ?.

10

Rest Ca: 0.66? (Al equivalent) / Cl: 2.69 Basicity: 63.2%

Complex SO 2 ions: 100%

Cl / (total SO 2): 5.15 Example 4:

Products not in accordance with the invention 25

Their gross formula is expressed in the same form as the soro formulas for the products of the invention.

4a) preparing a basic aluminum chlorosulfal according to the prior art, which is in the form of a solution containing by weight:

Eel ; 10.3 (expressed as A1: 0. <) 35 Cl: 9.09 m DK 172765 B1 11

Total SO.f ”: 2.49

Basicity: 51.32 *, 5 where the basicity is defined as for the product according to the invention.

The concentration of complex SO 2 ions is 1.64, ie 1.64 ie 65.9% of the sulfate is complex.

2.49

The ratio (Al equivalent) / Cl is 2.37 and the ratio Cl / (Total SO /) is 3.65. The product is prepared by reaction between alumina and HCl and II.:SO4, as disclosed in French Patent Specification No. 2,036,685.

4b) another basic aluminum chlorosulfate is prepared which is in the form of a solution containing in% by weight: 20

Al: 8.3 (expressed as Al .. O ·.)

Cl: 5.21 Total SO, 7-: 5.02

Basicity is: 49.8%

The concentration of complex SO / 7 'ions is 1.5, ie. that 1.5 29.9% of the sulfate is complex.

5, 02

The ratio (Al equivalent) / Cl is 3.32 and the ratio

Cl / (total SO / 7 ”) is 1.04.

35 DK 172765 B1 12

This product is prepared by a process comprising a step of preparing a liquid of calcium chloride and of calcium carbonate a chlorocarbonate-containing liquid), a step of contacting between the chlorocarbonate liquid and the aluminum sulfate, then a step of separating the reaction mixture thus obtained. separating a cake of calcium sulfate from a filtrate containing the basic aluminum chlorosulfate.

This process is described in European Patent Application Serial No. 218,487.

An apparent hydrodynamic diameter ζζ of 70 nm (700A) has been measured for this product by quasi-elastic diffusion of light.

4c) A product of the same kind as in 4b) is produced. The concentrations are: 20 Al: 8.55 (as Al.00

Cl: 6.82

Total SO, δ: 2.74

Complex SO / ': 1.93

The basicity is: 57'i The percentage is complex SO / - is thus 1.93 = 70.4 *, and the 2.74 ratio (Al equivalent) / Cl is 2.64, and the ratio Cl / (Total S0 / ') is 2.49.

EXAMPLE 5:

This example illustrates the use of the product of the invention.

The product according to the invention is compared with the products of the above Comparative Example 4.

Experiments are carried out in the so-called soil test, using the following procedure: - 1 liter carrier glass, - temperature 15 "C, 15 - river water, - jar test" hydrocure "type SLH6, 20 - rapid stirring for 1 minute and 30 seconds after the addition of flocculant and then slow stirring, ie sufficient for confluence, but avoiding decanting the flocks.

25

It is then allowed to decant for 3, 10 or 20 minutes, as shown in Tables 1-7.

- measuring the residual aluminum content in the water by a 30 polyometric method using chromazurol after filtering the decanted water for 20 minutes over a 0.45 µm pore filter.

DK 172765 B1 14 The following tables indicate the type of water to be treated, the pH value, the cloudiness expressed as NTU and the organic constituents expressed in mg of oxygen per day. liters of water.

5

The products listed in the table are characterized by the number of the corresponding example. The turbidity of water at the surface is indicated after x minutes of decantation, final pH and the organic materials and aluminum as residue in the water (residual Al) expressed in ppb (pg / liter).

Tables 1-7 show the results obtained.

TABLE 1

Water type; water from the river Seine 20 pH: 7.97

Obscurity; 42 NTU

Organic materials (MO): 6.96 mg 0 / l 25 I I 1 -—- 1-Γ - 1-1

In 1 Quantity | Blur in superna- | | | IN

I Product I in g / m3 1 natant | III

I (No. of | (as | -, - 1- | end | | Remainder | 30 Ieks) IΛ1 _. (),) I 3 »I 10 '| 20 '| arrow | M.O. | Λ1 | I-1 - I-1-l · --- 1-1-I --- 1 I 3 I 4 I 2.1 I 1.45 I 1.3 I 7.7 (2.76 | 148 [I 1 I 4 I 1.8, I 1.35 I 1.2 I 7.8412.72 i 97 |

1 -> -____ I_I_I_1__1______I_I

DK 172765 B1 TABLE 2 15

Water type: water from river Marne 5 pH: 8.02

Obscurity: 60 NTU

Organic matr. (M.O.): 6.68 mg 0.; / l 10

I-1-1-1-1 in I

I In Quantity | Blur in superna- | | | |

In Product I in g / m3 | natant I I I I

I (No. of | (as | -1-1- | End | | Remainder | 15 I ex) | A], Oj) I 3 '| 10 '| 20 '| pH | M.O. | Al | I- I - 1-1-1-1 ---] - I-1 I 4a I 3 I 1.7 I 1.6 I 1.5 17.78 | 2.94 | 152 | I 4c I e I 1.7 I 1.55 | 1.45 | 7.80 | 2.78 | 152 | I 1 I 3 I 1.8 I 1.6 I 1, 4 17, 80 12, 661 118 |

2 o I__1 __'_ I___I__I_i_i______I

TABLE 3 25

Water type: Water from the river Marne pH: 8.26 (has been modified by the addition of sodium hydroxide)

Obscurity: 55 NTU

Organic matr. (M.O.): 5.94 mg O./l DK 172765 B1 16 I-1-i-1-1-1--1 I | Quantity | Blur in superna- | | | | In Product I in g / m3 | natant 1111 I (No. of I (as | -1-1-Islut | | Rest | 5 I ex) [Al.Oj) | 3 '| 10 '| 20 '| pH | M.O. | Al [I-1 -, --- 1 --- 1 --- [- 1--1 --- 1 I 4a 1 3 I 1.55 | 1.55 | 1.35 17.90} 2.12 [216 | I 4c 1 3 I 1.6 I 1.55 I 1.3 | 7.92 | 2.14j 212 | I 1 1 3 I 1.7 I 1.55 I 1.45 | 7.97 | 2.08 | 165 (I o I_1_I_I_I_1__I_1-1 TABLE 4

Water Type: Water from River Oise 15 pH: 7.99

Obscurity: 9.9 NTU

20 Organic matr. (M.O.): 5.64 mg O ^ / l

I I I I I I I I

I (Quantity | Blur in superna- ||||

In Product I in g / m3 | natant I I I I

I (No. of I (as | -1-1- | End | (Remaining | 25 Ex) 1 Al ^ Oi) | 3 '| 10' | 20 '| pH | MO | Al | Ii ---- --1-1--1 ----, - 1-1 --- | I 1 I 3 I 1.0 I 0.88 1 0.80 | 7.88 | 2.94 | 89 | I 4a I 3 I 0.98 I 0.93 | 0.91 | 7.84 | 3.101 123 | I 4b I 3 I 1.2 I 1.02 I 0.91 | 7.82 | 3.08 | 120 | 30 I_L ____ L__I ___ L__I ___ 1-L-1 TABLE 5 DK 172765 B1 17

Water Type: Water from River Oise 5 pH: 8.24 (after addition of sodium hydroxide)

Obscurity: 21 NTU

10 Organic matr. (M.O.): 6.92 mg O./l i i-1-i i i i 15 I I Quantity | Blur in superna- | | | |

I Product I in g / m3 j natant I I I I

I (No. of I (as | -1-1- | End | | Rest | (ex) | Al, Oj) I 3 'I 10' | 20 '| pH | MO | Al |, -1-1- 1-1 --- 1 — i — I - 1 20 I 1 I 3 I 0.94 I 0.83 | 0, 72 18, 08 12, 861 163 | I 4a I 3 I 1.05 I 1 | 0.99 | 8.03 12.8 61 242 | I 4b I 3 I 1.25 I 0.99 | 0, 93 18, 02 12, 88 (238 |

I - I_I ___ I____1_____I____I_I_____I

25 It is seen that even with a very basic water material, the product according to the invention makes it possible to be below the maximum concentration of 2 µg / l allowed as permitted by the Council of Europe Directive of 15 July 1980.

TABLE 6

Water type: Water from the river Seine 35 pH: 7.97 DK 172765 B1 18

Obscurity: 42 NTU

Organic matr. (M.O.): 6.96 mg of 0 ../ 1

5 I-1 I j [I I

In Quantity | Blur in superna- | | | |

In Product I in g / m3 | natant I I I I

I (No. of | (as | -1-1- (End ((Remain | Ex)) In ΑΙ.Όι) I 3 '| 10' | 20 '| pli | MO | Al | 10 1-1-1 -1-1-1-1--1--1 I 4a I 4 I 2.15 | 1.45 | 1.3 17.7 12.76 J 148 | I 2 I 3 I 2.2 I 1, 2 I 1.3 | 7.77 (2.72 (117 | I 1 I 4 I 3.0 I 1.40 I 1.3 17, 81 12.721 104 | I_I__I_I__1 _! _ I-1--1 TABLE 7

Water type: Water from the river Marne 20 pH: 8.02

Obscurity: 60 NTU

Organic matr. (M.O.): 6.68 mg 0 ° · / 1 25 I-1-1--1-i-1-1 (Quantity | Cloudiness in supernal || (|

(Product I in g / m3 (natant I [I I

I (No. of | (as | -1-1- | SluL | | Remaining | 30 (ex) IAl_0j) | 3 '| 10' | 20 '| pH (MO | Al | 1-1--1-1 -1 -, - 1-1- (I 4a I 3 1 1.7 I 1.6 | 1.5 (7.78 | 2.94 | 152 | I 4c I 3 I 1.6 (1.55 I 1.45 (7.80 12.781 152 | I 2 I 3 I 1.8 I 1.6 I 1, 5 17, 82 (2.72 (128 | 35 (1 I 3 I 1.8 I 1.6 I 1.4 | 7, 80 (2, 661 118 | I______I___I_I______J_I__I I_1 EXAMPLE 6 19 DK 172765 B1

This example consists of a comparison of the results with respect to cloudiness and residual content of aluminum in the products of the invention of Examples 1 and 3 when used at very low content concentrations: 1, 1.5, 2 and 3 g / m * measured like Al.Oj.

The tests are carried out by so-called jar tests using 10 of the procedure described in Example 5 and using water of the Seine river type.

Table 8 lists the pH values, the cloudiness, and the amount of organic matter in the 15 Seine River water measured prior to treatment using the products of Examples 1 and 3 (Experiments Λ - P).

TABLE 8 20 i-1 i-r - 1 | Test No. | pH water | obscurity (NTU) | M.O. (mg 0 ^ / 1) |

I A I I I 5.88 I

25 I B-C I I I 6.08 I

| D-E | 8.02 | 8.2 I I

I F-G I 8.05 I 7.4 I I

I H-I I I 10.0 I 5.88 I

I J-K I I 10.0 I 5.48 I

30 I L I 8.10 I 12.0 I 4.68 |

I M-N I 8.00 I 8.3 I I

I O-P I 7.91 I 12 I I

I - 1_I_1__I

35 DK 172765 B1 20 Table 9 uses the average values of the results obtained by reference for the product of Example 3. The percentages shown are obtained as follows: 5 -, t, .. x fcks. i,. , nn range of parameters x {?,) = the value of x for example; 3 x 100-100 with i = 1 or 3, 10 N.B. The calculated values are not shown to be significant unless their absolute value is> or = 5¾.

TABLE 9 15 i-i-1-1 I I I Difference of | I i i ------, -, - i I | Quantity | Supernatant cloudiness | M.O | Rest | 20 I Product I in g / m3 | % [| Al j I (No. of | (as | -, - 1--1 | |

Ieks) | A1.0j I 3 'I 10T | 20 | (Ί) | (?) | 1-1 ---------- 1--1-H ------ 1 —— I --- 1 I 1 II 14 I 9.3 I 8.9 I -0.7 I - |

25 I 3 1 1 I 0 I 0 | 0 I 0 I 0 I

I I I I I I I I

il I I 18 I 9.2 I 6 I 1.8 I- 10 I

I 3 I 1.5 I 0 I 0 I 0 I 0 I o I

I I I I I I I I

30 I 1 I I 20 I 9.9 I 3.3 I | | I 3 I 2 I 0 I 0 I 0 I 0 I 0 [

I I I I I I I I

I 1 I I 5.25 I 0.34 I -2.4 | - | - | I 3 I 3 I o you | o j o 1 j 35 1-1-1-1-1-1 ----- 1 ----------- 1

Claims (9)

Basic aluminum chlorosulfate, in the form of an aqueous solution, characterized in that it comprises: - a product of the formula: Al "C 1" (OH SO,) r X ", wherein:. n, m, p and k represent the molar concentrations (mol / l) of the components of solution, X represents an alkaline earth metal, preferably calcium,. less than 20% of the SCVv ions can be precipitated by 20 roaction with barium chloride at room temperature and whose basicity: 3n + 2k - m - 2p 3n is between 45 and 70? ·. 25 Basic aluminum chlorosulfate according to claim 1, characterized in that the ratio (Al equivalent) / C.l, 3n / m is less than 2.8. Basic aluminium chlorosulfate according to claim 1 or 2, characterized in that the basicity is between 50 and 65%. Basic aluminum chlorosulfate according to any one of claims 35 to 1-3, characterized in that the ratio (-1 equivalent / Cl is less than 2.75. DK 172765 B1 5. Basic aluminum aluminum chlorosulfate according to any one of claims 1-4, characterized in that less than 5¾ of the SO 1 ions can be precipitated by reaction with barium chloride at room temperature. Basic aluminum chlorine sulfate according to any one of claims 1-5, characterized in that: its basicity is greater than or equal to 10 by 60% and the weight ratio Cl / SCh is between 4.5 and 8. Process for the preparation of basic aluminum chlorosulfate according to claim 1, characterized in that, (a) aluminum oxide, hydrochloric acid and sulfuric acid are contacted with an aqueous solution in the following proportions: 1.89 <HCI ____ <2.44 aluminum 25 1.37 <_H ^ SO | _____ <1.73 aluminum as aluminum is expressed as AJ ... Oj and the ratios are molar, b) this solution is contacted with an alkaline earth metal compound, the molar ratio of the alkaline earth metal compound to the aluminum expressed as Al; Oj is between 1.63 and 1.10, c) The alkaline earth metal sulfate is removed. DK 172765 B1 Process according to claim 7, characterized in that the alkaline earth metal compound is selected from calcium carbonate, hydroxide, oxide and hydrogen carbonate. Method for treating an aqueous medium, characterized in that a product according to any one of claims 1-6 is used.