MXPA97001790A - Procedure for the preparation of aluminum basic polycollosulphates and applications of the mis - Google Patents

Abstract

The present invention refers to a process for the preparation of highly basic polyaluminium chlorosulfate, having the general formula: Al (OH) aClbYc / dM'C12 (eM "c1 in which Y represents a valence 2 anion, such as SO42-M 'represents a cation of valence 2, such as an alkaline earth metal, M "represents a cation of valence 1, such as an alkali metal or ammonium, a, b, c and d are positive non-zero integers or positive fractions and e can be zero or a positive integer or positive fraction such that 1.8

Description

PROCEDURE FOR THE PREPARATION OF BASIC ALUMINUM POLYCELLOSULPHATES AND APPLICATIONS THEREOF DESCRIPTIVE MEMORY The present invention relates to a process for the preparation of high basicity aluminum and to the application of these polyaluryl chlorosulfates or to the treatment of drinking water, aqueous effluents and in the paper industry. Polyaluminium chlorosulfates have the general formula: 01 (0H) aClbYc / dM'Cl2 / et "Cl (I) in which Y represents a valence anion 2, as 0« 2- tn 'represents a valence cation 2, With an alkaline earth metal, M "represents a valence cation l, co or an alkaline or ammonium metal, a, b, c and d are positive integers of non-zero or positive fractions, e can be zero or a positive integer or a fraction positive, b = 3-2c-a and 2d + e + b _ < . 3. Basicity | 3 is defined by the ratio a / 3 expressed as a percentage, and can be on the scale of 20 to 75%. Starting with the chemical composition, it can be calculated by the following formula: ß = 100 (301 + 2 go + Pl "- 2Y - CD / 3 Al, in which Al, M ',", Y and Cl are expressed in moles. Polyaluminium chlorosulfates, hereinafter referred to as PACS, are widely used in industry, in particular in the manufacture of paper and for the treatment of waste water and especially drinking water, where their high quality of coagulation and flocculation they make a product of choice. More precisely, for the treatment of water, processes are desired that avoid any formation of effluents, in particular gypsum (CaSO «-2H2?) And which make it possible to manufacture products that have capacities for flocculation-coagulation of materials in suspension in drinking water, capacities to release only very little soluble aluminum in the treated drinking water and storage stability of the PAC solutions? for several months, this means that it includes temperature variations between 0 ° C and 40 ° C or even higher if the storage is not protected from the sun's rays. EP 327,419 discloses a process for the manufacture of high basicity PACS which satisfies the capacities and stability as mentioned above. However, this procedure generates a gypsum effluent whose discharge into the river water has environmental problems and whose disposal involves additional costs. The efficiency of flocculation-coagulation is evaluated by measuring the turbidity of the supernatant water phase after treatment with a PACS. Large flocs with fast separation properties after the sedimentation has taken place are separated, while the smaller flocs can be placed in a sand filter and must have an excellent capacity to be absorbed in a sand filter. I. EFFECTIVENESS The complete filtration in a sand filter is characterized by the number of particles per cm3, which are found in clarified waters. The ability to only release a very low residual aluminum content in drinking water is evaluated by filtering the treated water through a 0.45 μm filter and testing the aluminum present. The PACS in solution is supposedly stable if it retains its application properties after storage for three months at room temperature and for a few months at 40 ° C, and if it does not deposit solids, at 40 ° C for one month or at room temperature (25 ° C). C) for three months. Several problems were created in the common PAC applications, resulting in particular from the manufacturing procedures. The elimination of turbidity, which is directly associated with flocculation-coagulation, requires a high sulphate content and a low temperature for the basification step, below 70 ° C, preferably below 40 ° C. When the sulfate content is high, the PACSs have a high temperature resistance. Without having a negative impact on the elimination of turbidity, it is then possible to carry out synthesis at 70 ° C, for example between 80 ° C and 90 ° C for a ratio of the percentages by mass of sulphate / alumina of more than 3 / 10.5. The treatment of drinking water requires the production of a low residue aluminum content in the treated water, which implies a high basicity of the PACSs, between 60% and 75%. The residual aluminum content in the treated water decreases when the PACSs are synthesized at high temperatures in the basification step, typically above 70 ° C and preferably between 80 ° C and 85 ° C. When the ratio of sulfate / alumina mass percentages increases from 0.1 / 10 to 3/10, the residual aluminum content increases rapidly to stabilize at a ratio of 3/10 to 23.8 / 8.5. The residual aluminum contents are very high for a ratio of the percentages by mass of sulphate / alumina greater than 0.1 / 10. To obtain PACSs that are effective in terms of residual alumina, it is necessary to have PACSs of high basicity, a high temperature for the basification step and a very low sulfate content in the PACSs. A high temperature and a low sulfate content are opposite conditions to the production of PACSs that are effective to eliminate turbidity. The PACSs in solution must be stable in storage and at temperatures of up to 40 ° C. The temperature stability of the PACSs in solution increases with increasing the sulfate / alumina loop ratio. The PACSs in solution are commonly very stable for sulphate / alumina mass ratio ratios greater than 3/10. In Japanese Patent JP-53 001699/1978, a process for the manufacture of polyaluminium chlorosulfate is described. This procedure consists, in a first step, of basifying a polysulfate chlorosulfate containing a lot of sulphate with an equuellar amount of CaC3, leading to the production of gypsum (CaS02 • 2H2O), which is separated. In a second step, the product of the previous step, whose hasicity is between 55% and 58%, is reacted with a compound selected from the group consisting of CaC 3, NaHCO 3, Na 2 C 3, M 2 OH and R 2, without exceed the temperature of 60 ° C. Although the basicity is between 65-70%, the residual aluminum contents in the treated waters are 30% to 60% higher than those obtained with the PACSs obtained in accordance with the process described in the aforementioned EP 327,419 patent. A temperature of 60 ° C is not sufficient and a temperature above 70 ° C degrades the flocculation-coagulation properties. The main disadvantage of this procedure lies in a considerable subproduction of gypsum whose waste has environmental problems, as mentioned above. Patent 3P 52 113384/1977 describes a process for the manufacture of basic chlorosulfato of 65-70% polyalumm by the addition of an alkaline agent such as CaC 3, NaHCO 3, Mg (0H) 2 and / or MgO to a solution of aluminum chloride or basic aluminum chloride, even at a temperature below 60 ° C. It is noted that the residual aluminum contents are again very high compared to the PACSs obtained in accordance with the procedure described in EP 327,419, for the same reasons as those explained above in the 3P-53 001699/1978 patent. A large amount of gypsum is underproduced, which is still a disadvantage. Canadian patent application CA 2,109,756 Al describes the manufacture of a flocculant, without the generation of gypsum, by adding gypsum to an aluminum chlorosulfate solution at a temperature between 45 ° C and 98 ° C, preferably 75 ° C. The plaster in this way added is completely dissolved; the calcium concentration remains limited on a scale from 0.1% to 0.4% Ca2 +. It is clearly indicated that the basification step with a base such as CaC 3 should be carried out at 45 ° C. The basicity of the product, obtained in accordance with that patent, is less than 55%. The ratio of mass percentages of sulfate / alumina is in the order of 3/10. However, when the examples were repeated it was not possible to reproduce the mentioned basicities of 55%, but instead lower basicities of between 10% and 15% were found. The residual aluminum contents are excessive when compared to the PACSs obtained in accordance with the process described in EP 327,419. In order to improve the remaining amount of aluminum remaining in the treated water, the aforementioned patent EP 327,419 proposes a process for the preparation of high basicity PACS, between 60% and 70%. This procedure consists in particular of placing an excess aluminum, chloride and sulphate solution in contact with a basic compound of alkaline earth, descending from 93 ° C to 65 ° C and subsequently removing the insoluble alkaline earth metal sulfate by filtration. It should be noted that the synthesis is initiated in a large amount of sulphate and that, simultaneously with the decrease in temperature, the sulfate content in the reaction medium decreases. The thermal degradation of PACS solutions, which are sensitive to low sulfate levels, is therefore avoided; typically for this product S0 * 2- = .g ?, AI2O3 = 10.5%. The high basicity PACS thus obtained make it possible to obtain lower contents of residual alumino in the treated water, as already mentioned above. However, this process has the great disadvantage of generating large amounts of gypsum (approximately 300 kg per ton of PACS produced). The patent EP 557,153 also describes a process for the preparation of PACS of high basicity, which leads to few influxes. However, this procedure has the disadvantage of being difficult to reproduce. This lack of reproduction ability is shown in particular by the production of a high level of residual aluminum in the treated water 8 out of 10 times. This residual level of aluminum can reach an amount that is 40% higher than that obtained with the PACSs described in EP 327,419.

It is recalled that to obtain PACSs that are effective in terms of residual aluminum, it is necessary to have a PACS of high basicity, manufactured at a high basification temperature with a low sulfate content in the PACSs. A high temperature and a low sulfate content are conditions that are opposite to the production of PACs that are effective in eliminating turbidity. This has been observed in particular in the patent FR 2,317,227 and European patent EP 0,557,153, in which it is impossible to overbassize basic aluminum chlorosulfate at 40% to about 55-70%, with a base, at a higher temperature at 70 ° C without preventing the degradation of the flocculent properties of the products. The temperature scale mentioned in the two p > Previous licenses are 40 ° C to 70 ° C for the first and 50 ° C to 70 ° C for the second. The products described in the patent FR 2,317,227 have basicities of between 40% and 55%, compared with 65% to 75% for the EP patent 0.55 ,, 153 Al. The ratio of the percentages by mass of? 42- / l2 ? 3 is less than 3 / 10.5. In accordance with EP 327,419, it is possible to work on 70 ° C starting the synthesis with an excess of sulphate, which is precipitated as gypsum. It is also possible to work over 70 ° C if you try to obtain a final product that contains more than 3% SOA2- for AI2O3 at 10.5%. The problem to solve is to obtain stable PACSs with good flocculent properties with an ability to pass very little residual aluminum to the treated water, being at the same time obliged to manufacture PACSs in accordance with a procedure that produces the least possible quantity of effluents. Moreover, it is desired by PACS users that smaller flocs should have good absorption properties in sand filters. A process for the preparation of high basicity polyaluminium chlorosulfate having the general formula: Al (0H), ClbYc / dp'Cl2 / eM "Cl (I) in which Y represents a valence anion 2 has now been discovered. , as SOA2", M 'represents a cation of valence 2, such as an alkaline earth metal, M" represents a cation of valence 1, such as an alkaline metal or ammonium, a, b, c and d are positive integers of non-zero or positive fractions , e can be zero or a positive integer or a positive fraction so that 1.8 < a < 2,25 0 ... 1 &ct; c < 0.150 b = 3-2c-a- and 2d + e + b _ < 3, and having a β basicity of between 60% and 75%, and preferably between 65% and 70%, this basicity being defined by the formula: β = 100 x (3A1 + 2 M '+ M "- 2Y-CD / 3 Al, in which Al, M ', M ", Y and Cl are expressed in rnoles, said process consists of placing a basic compound of an alkali metal, preferably in aqueous solution, and at least one compound basic d e) an alkaline earth metal or a halide of an alkaline earth metal, in aqueous suspension or in powder form, in the presence of sulphate ions, in contact with a basic solution of aluminum chloride of the formula: Al (0H)? Cly (II ) in which x is a number between 0.1 and 1.5 and y = 3-x, at a temperature between room temperature (about 25 ° C) and 70 ° C, said method being further characterized because after the basification, the medium obtained reaction is cooked at a temperature, known as the cooking temperature between 60 ° C and 95 ° C so that the cooking time is between 3 h and 20 h, and preferably between 5 h and 9 h for a cooking temperature of 60 ° C and for which the cooking time is between 5 minutes and 15 minutes, and preferably between 7 minutes and 10 minutes, for a cooking temperature of 95 ° C. According to the present invention, the cooking times for the cooking temperatures of 7Q ° C, 80 ° C, 85 ° C and 90 ° C are shown in the following table.

For all intermediate cooking temperatures, a person skilled in the art will proceed by extrapolation. According to the present invention, the ratio of sulfate / alumina mass percentages is advantageously less than 3 / 10.5 and preferably between 1 / 10.5 and 1.5 / 10.5. In accordance with the present invention, the reagents are preferably placed in contact with vigorous agitation and / or vigorous turbulence. In this way, any means that makes it possible to obtain high turbulence, such as injection with a nozzle or venturi, can be used. The cooking is advantageously carried out with stirring, which is preferably less vigorous than that carried out with the reagents being placed in contact.

According to the present invention, the expression "basic compound of an alkali metal" denotes any derivative of said alkali metal having a basic nature, in particular oxide, hydroxide, carbonate or bicarbonate. As an illustration of basic alkaline metal compounds that can be used in accordance with the present invention, there will be mentioned NaOH, KOH, NaHC 3, Na 2 C 3, K 2 CO 3, KHCO 3 and mixtures of at least two of the compounds of an alkali metal listed above. Preferably, NaOH, or Na 2 C 3, will be used. These compounds are preferably used in the form of an aqueous solution. The rnolar concentration of the basic compound of the alkali metal is at least equal to 2 mol / 1 and preferably between 4 mol / 1 and 7 raol / 1. According to the present invention, the term "basic compound of an alkaline earth metal" denotes any derivative of said alkaline earth metal having a basic nature, in particular oxide, hydroxide, carbonate or bicarbonate. As an illustration of basic compounds of an alkaline earth metal which can be used according to the present invention, there will be mentioned CaO, MgO, Ca (0H) 2, Mg (0H) 2, CaCO3 and mixtures of at least two of the Basic compounds of an alkaline earth metal listed above. Preferably, Ca (0H) 2, Mg (0H) 2 or MgO will be used. By way of illustration of halides of an alkaline earth metal which can be used according to the present invention, CaCl 2 and MgCl 2 will be mentioned.

Preferably CaCl 2 will be used. In accordance with the present invention, the sulfate ions can be provided by compounds such as H2SO4, a2O < 4, CaSO? , CaSO < v'2H2? or MgS? 4. Preferably, they will be used H2 SO4, Na2 SO4 and Ca2 O4 • 2H20 (gypsum). In accordance with the present invention, the reagents can be introduced in different orders and it has been demonstrated that the order of introduction of the reagents had no consequences on the quality of the PACSs obtained in accordance with the present invention. In this way, in particular, the basic solution of aluminum chloride (II) can be placed in contact simultaneously with the basic compound of an alkali metal and the sulfate, followed by the introduction into a reaction medium obtained from the basic compound of a alkaline earth metal (in suspension or in powder form), or conversely, the solution may be placed in contact with the alkaline earth metal basic compound, followed by the simultaneous introduction of the basic compound into an alkali metal and the sulfate. According to another variant, the basic solution of aluminum (II) chloride and CaCl2 can be placed in contact, followed by the simultaneous introduction into the reaction medium thus obtained of the basic compound of an alkali metal and the sulfate. The above procedures made it possible to improve one or more features to the detriment of one or more other features. In accordance with the present invention, PACs are obtained according to an improved process called "clean", which means a process that produces virtually no by-products such as gypsum. In addition, the process according to the present invention leads to high basicity PACs which have simultaneous storage stability, turbidity elimination and residual aluminum content characteristics in the treated waters. The PACSs according to the present invention can be used in many fields such as, for example, to treat drinking water, aqueous effluents and in the paper industry. Preferably, the PACSs of the present invention can be advantageously used to treat drinking water. The following examples illustrate the invention.

EXAMPLE 1 (In accordance with the invention) 500 g of a basic aluminum polychloride are introduced into a 2 liter reactor. This polychloride contains 11.18% aluminum based on AI2 O3, 21.61% chloride and possesses a basicity of 42.9%. Its empirical formula is: Al (OH) 1. 28 Cll. 7 1 - 19.2 g of lime Ca (0H) 2 are then added to the reactor which contains the polychloride maintained at 50 ° C. The addition time is 45 minutes with a Rushton agitation set at 800 rev / min. A basic solution of sodium carbonate and sodium sulphate is prepared according to the following procedure: 13.15 g of sulfuric acid at a concentration of 77.1% in the loop are poured into a sodium carbonate solution containing 68.5 g of a2C? 3 -H2? and 300 g of water. This basic solution preheated to 50 ° C is added, with vigorous turbulence, to the reactor containing the polychlorine and Ca (0H) 2 maintained at 50 ° C, for 30 minutes. At the end of basification, the stirring speed is reduced to 200 revolutions per minute. 10 g of solid gypsum CaS? 3-2H2? they are then added to obtain a constant concentration of CaS? 3-2H2 ?, and the temperature is brought from 50 ° C to 85 ° C for 30 minutes, after which the cooking is carried out for 1 hour at 85 ° C with agitation set at 200 revolutions per minute. The product is cooled to 40 ° C for 30 minutes and then filtrate. The plaster is recyclable. The recovered filtrate, giving a titre of approximately 9% alumina, is diluted by adding water until a density of 1,203 is obtained, that is, a content by weight of alumina of 8.5%. The chemical composition by weight, determined by analysis, is as follows: AI2O3: 8.71% Ca2 + 0.99% Na + 2.20% Cl- 10.45% S042"0.93% water: 76.9% calculated by difference The established reaction of the reagents and by the analysis of the finished products is as follows: Rl (0H)? 2? Cl? .7l + 0.14 Ca (0H) 2 + 0.223 Na2C03 + 0.057 Na2S0.? + 0.223 H20 Al (OH) 2.oiClo.β7 (SO / i) o.?57 - 0.14 CaCl2 + 0.550 NaCl + 0.223 CO2 resulting in a basicity of 2.01 / 3 = 67.1% EXAMPLE 2 (In accordance with the invention) 500 g of a basic aluminum polychloride are introduced into a 2 liter reactor. This polychloride contains 18.33% aluminum based on AI2 O3, 21.78% chloride and has a basicity of 43.1%. Its empirical formula is: Al (OH)? .29Cl? .71. 19. 2 g of Ca (0H) 2 are subsequently added to the reactor containing the polychloride maintaining at 50 ° C. The addition time ee of 45 minutes with a Rushton type stirring adjusted to 800 revolutions per minute. A basic solution of sodium carbonate and sodium sulfate is prepared according to the following procedure: 13.15 g of sulfuric acid at a concentration of 77.1% by mass are poured into a sodium carbonate solution containing 68.5 g of a2C0s 2O and 300 g of water. This basic solution preheated to 50 ° C is added, with vigorous turbulence, to the reactor containing the polychloride and to Ca (0H) 2 maintained at 50 ° C for 30 minutes. At the end of basification, the stirring speed is reduced to 200 revolutions per minute. The temperature is brought from 50 ° C to 85 ° C for 15 minutes, after which the cooking is carried out for 1 hour at 85 ° C, adjusting the stirring at 200 revolutions per minute. The product is cooled to 40 ° C for 30 minutes and subsequently clarified by filtration. The residue is less than 0.5 g / kg. The recovered filtrate, giving a titre of approximately 9% alumina, is diluted by adding water until a density of 1.205 is obtained, that is, a content by weight of alumina of 8.5%.

The chemical composition by weight, determined by analysis is as follows: AI2O3: 8.64% Ca2 +: 0.92% Na +: 2.25% Cl-: .1.0.21% S? 42 ~: 0.92% water: 76.9% calculated by difference. The established reaction of the reactants and by the analysis of the finished products is as follows: Al (0H)? 29Cl? .7l + 0.15 Ca (0H) 2 + 0.229 Na2C? 3 + 0.063 a2S? 4 + 0.229 H2O Al ( OH) 2.? 3Clo.84 (S? 4) o.?63 + 0.15 CaCl2 + 0.584 NaCl + 0.229 CO2 resulting in a basicity of 2.03 / 3 = 67.7% EXAMPLE 3 (In accordance with the invention) The procedure is carried out as in Example 2 with the same reagents, except that the temperature rise from 50 ° C to 80 ° C is carried out for 30 minutes and the cooking temperature is 80 ° C for 1 hour. h 30 minutes adjusting the agitation at 200 revolutions per minute.

EXAMPLE 4 (In accordance with the invention) The procedure is carried out as in Example 2 with the same reagents, except that the temperature rise from 50 ° C to 90 ° C is carried out for 30 minutes and the cooking temperature is 90 ° C for 20 minutes. minutes adjusting the agitation to 200 revolutions per minute.

EXAMPLE 5 (In accordance with the invention) The procedure is carried out as in example 2 with the same reactive, except that the temperature rise from 50 ° C to 95 ° C is carried out for 30 minutes and the cooking temperature is 95 ° C for 7 minutes. minutes adjusting the agitation to 200 revolutions per minute.

EXAMPLE 6 (Not in accordance with the invention) The procedure is carried out as in the patent EP 0,557, 153,. except that sodium carbonate in solution is used instead of sodium carbonate powder. The cooking of our invention is not carried out after basification. 500 g of a basic aluminum polychloride are introduced into a 2 liter reactor. This polychloride contains 18.33% aluminum based on AI2 O3, 21.47% chloride and possesses a basicity of 43.3%. Its empirical formula is: Al (OH) 1. 30 Cli. 70 - A basic solution of sodium carbonate and sodium sulfate is prepared according to the following procedure: 13.15 g of sulfuric acid at a concentration of 77.1% by mass are poured into a sodium carbonate solution containing 68.5 g of a2C? 3-H2? and 300 g of water. This basic solution preheated to 60 ° C is added, with vigorous turbulence, to the reactor containing the polychloride kept at 60 ° C for 20 minutes. 19.2 g of Ca (0H) 2 are added to the reactor containing the polychloride and the basic solution maintained at 60 ° C. The addition time is 45 mutually with a Rushton type stirring set at 800 revolutions per minute. At the end of the basification of calcium, the stirring speed is reduced to 200 revolutions per minute. The product is stirred for 30 minutes and is then cooled to 40 ° C for 20 minutes and then filtered. The recovered filtrate, giving a title of approximately 9% alumina, is diluted by adding water until a density of 1,204 is obtained, ie a content by weight of alumina of 8.5%. This is stored at room temperature. The chemical composition by weight, after the analysis is as follows: AI2O3: 8.6.1% Ca2 +: 0.95% Na +: 2.25% Cl-: 10.26% SO42-: 0.93% water: 77.0% calculated by difference. The reaction is as follows: Al (OH)? 3? Cl? .7? + 0.14 Ca (0H) 2 + 0.233 Na2C? 3 + 0.063 aa S0 «+ 0.233 H20 Al (OH) 2.? 3sClo.8s (S? 4)? 067 + 0.14 C Cl2 + 0.579 NaCl + 0.233 CO2 resulting in a basicity of 2.035 / 3 = 67.8% EXAMPLE 7 (In accordance with the invention) The product obtained after basification of calcium, according to example 6, is heated at 70 ° C for 20 minutes and the cooking is subsequently carried out at 70 ° C for 2 hours 30 minutes by adjusting the stirring at 200 revolutions per minute. The residual content of aluminum in the treated water improves from 140% (obtained with the PAC? According to the procedure of the patent EP 327,419) to z > ? .120% with the product of the present example.

EXAMPLE 8 (In accordance with the invention) The experiment described in Example 6 is repeated in a 200 liter reactor, except that Ca (OH) 2 is first introduced, followed by the mixture of sodium carbonate and sodium sulfate in solution at the level of the stirring paddle. 5 rn / s through a nozzle. The cooking described in example 7 is carried out. After cooking for 2 hours 30 minutes, a product is obtained which makes it possible to obtain a treated water which contains 104% of the residual aluminum instead of 140% with the PACS manufactured according to example 6 (the PACS was not subjected to to no cooking). It was observed that with this type of cooking, at a temperature of 70 ° C, a quantity of gypsum in suspension equal to approximately 200 g / ton was found in the liquid.

EXAMPLE 9 (In accordance with the invention) 500 g of a basic aluminum polychloride are introduced into a 2 liter reactor. This polychloride contains 18.33% aluminum based on AI2O3, 21.78% chloride and possesses a basicity of 43.1%. Its empirical formula is: Al (0H) l.29Cll.71. 19.2 g of Ca (0H) 2 are subsequently added to the reactor containing the polychloride maintained at 50 ° C. The addition time is 45 minutes with a Rushton agitation set at 800 revolutions per minute. A basic solution of sodium carbonate and sodium sulfate is prepared according to the following procedure: 13.15 g of sulfuric acid at a concentration of 77.1% by mass are poured into a sodium carbonate solution containing 68.5 g of Na2C? 3 -H2? and 300 g of water. Eeta basic solution preheated to 50 ° C is added, with vigorous turbulence, to the reactor containing the polychloride and Ca (0H) 2 kept at 50 ° C for 30 minutes. At the end of basification, the stirring speed is reduced to 200 revolutions per minute. The temperature is brought from 50 ° C to 60 ° C for 10 minutes, after which cooking is carried out for 5 hours at 60 ° C by adjusting the stirring at 200 revolutions per minute. The product is cooled to 40 ° C for 30 minutes and then filtered. The recovered filtrate, giving a titre of approximately 9% alumina, is diluted by adding water until a deficiency of 1,202 is obtained, that is to say an alum content of 8.5%.

The chemical composition by weight, determined by the analysis, is as follows: AI2O3: 8.46% Ca +: 0.95% Na +: 2.25% Cl-: .1.0.07% SO42-: 0.95% water: 77% calculated by difference. The reaction established from the reagents and by analysis of the finished products is as follows: RH OH) 1.29 Cli.71 + 0.15 CaiOH + 0.223 Na2C03 + 0.072 Na2 SO4 + 0.223 H2O A1 (0H) 2.03 Cio.82 (S? 4) o.?72 + 0.15 CaCl2 + 0.590 NaCl + 0.223 CO2 resulting in a basicity of 2.03 / 3 = 67.7% EXAMPLE 10 (in accordance with the invention) 500 g of basic aluminum polychloride are introduced into a 2 liter reactor. This polychloride contains 18.13% aluminum based on AI2O3, 21.47% chloride and has a basicity of 43.3%. Its empirical formula is: Al (0H)? 30CI1.70. 13.15 g of sulfuric acid at a concentration of 77. 1% by mass are emptied into said polychloride at 50 ° C for 14 minutes. 19.2 g. of Ca (0H) 2 are then added at 50 ° C. The addition time is 45 minutes with Rushton agitation set to 800 rev / rnin. Once the addition of Ca (0H) 2 is complete, a sodium carbonate solution containing 68.5 g is added. of Na2C? 3-H2? and 300 g of water with vigorous turbulence maintained at 50 ° C for 20 minutes. At the end of the basification, the stirring speed is reduced to 200 revolutions per minute and the product is heated at 70 ° C for 15 minutes and then cooked at 70 ° C for 2 hours 30 minutes with agitation set at 200 revolutions per minute . The product is cooled to 40 ° C for 20 minutes, filtered and diluted with 121 g of water. The recovered filtrate has a density of 1,204, ie a content by weight of alumina of 8.5%. It is stored at room temperature. The chemical composition by weight, after the analysis, is as follows: AI2O3: 8.51% Ca2 +: 0.92% N *: 2.37% Cl-: 10.04% O * 2-: 0.90% Water: 77.25% calculated by difference.

The reaction is as follows: Al (0H)? 3? Cl? .7? + 0-14 Ca (0H) 2 + 0.254 Na2C03 + 0.056 Na2 SO * + 0.254 H20 Al (OH) 2.? 8Clo.8l ( ?? 4) o.05 + 0.14 CaCl2 + 0.52 NaCl + 0.254 C02 resulting in a basicity of 2.08 / 3 = 69.3% EXAMPLE 11 (in accordance with the invention) The same test as in Example 7 was carried out, except that Ca (0H) 2 is introduced in the second place and the mixture of basifying solution of carbonate and sodium sulfate is introduced first. The same analytical results are obtained as for PACS from Example 7.

EXAMPLE 12 (In accordance with the invention) 750 g of a basic aluminum polychloride are introduced into a 2 liter reactor. This polychloride contains 18.33% aluminum based on AI2O3, 21.78% chloride and have a basicity of 43.1%. S? Empirical formula is: Al (OH)? 3? Cl? .70 - 28.8 g. of Ca (0H) 2 ee are added to the reactor containing the polychloride maintained at 50 ° C. The addition time ee of 45 minutes with Rushton type stirring adjusted to 800 rev / rnin. A basic solution of NaOH and sodium sulfate are prepared according to the following procedure: 19.7 g of sulfuric acid at a concentration of 77.1 mass% is emptied into 363.4 g of a NaOH solution containing 6 moles of NaOH / 1, followed by the addition of 88.7 g of water. This basic solution preheated to 50 ° C is added, with vigorous turbulence to the reactor containing the polychloride and Ca (0H) 2 kept at 50 ° C for 20 minutes. At the end of the basification the agitation speed is reduced to 200 revolutions per minute and the mixture is then allowed to stir for 10 minutes. The temperature is brought from 50 ° C to 70 ° C for 25 minutes after which it is cooked for 2 hours 30 minutes at 70 ° C with agitation set at 200 revolutions per minute. The product is cooled to 0 ° C for 30 minutes and then clarified by filtration. The residue is less than 0.2 g / kg. The recovered filtrate, which gives a titre of about 9% alumina, is diluted by adding water to obtain a density of 1,202, that is, a content by weight of alumina of 8.5%. The chemical composition by weight, determined by analysis, is as follows: AI2O3: 8.57% Ca2 +: 0.89% Na +: 2.50% Cl-: 10.11% S042": 0.92% water: 77.0% calculated by difference The reaction established from the reagents and by analysis of the finished products is as follows: Al (0H)? 29Cl? .7l + 0.13 Ca (0H) 2 + 0.536 NaOH + 0.057 Na2 SO4 Al (OH) 2.? oClo.78 (SO4) o.os7 + 0-13 CaCl2 + 0.65 NaCl resulting in a basicity of 2.1 / 3 = 70.0% EXAMPLE 13 (In accordance with the invention) 500 g of a basic aluminum polychloride are introduced into a 2 liter reactor. This polychloride contains 18. 33% aluminum based on AI2 O3, 21.78% chloride and have a basicity of 43.1%. Its empirical formula is: AH 0H)? . 29 Cll. 71-30.06 of calcium chloride are added afterwards to the reactor containing the polychloride maintained at 50 ° C. The purity of CaCl2 is 96%, the rest being NaCl and water. The addition time is 30 minutes with Rushton type stirring adjusted to 800 rev / rnin. An additional 15 minutes is required to dissolve the calcium chloride. A basic solution of NaOH and sodium sulfate ee is prepared according to the following procedure: 13.15 g of sulfuric acid at a concentration of 77.1% by mass is poured into 325.8 g of a NaOH solution containing 6 rnoles of NaOH / 1, followed by the addition of 42.7 g of water. This solution is preheated to 50 ° C and then added with vigorous turbulence at a linear velocity of about 4 rn / s in the reactor containing the polychloride and CaCl 2 maintained at 50 ° C for 20 minutes. At the end of basification, the stirring speed is reduced to 200 revolutions per minute and the mixture is then allowed to stir for 10 minutes. The temperature is brought from 50 ° C to 70 ° C for 25 minutes, after which it is cooked for 2 hours at 70 ° C with agitation set at 200 revolutions per minute. The product is cooled to 40 ° C for 30 minutes and then clarified by filtration. The residue is less than 0.1 g / kg. The recovered filtrate is diluted by adding water to obtain a density of 1,202, ie a content by weight of alumina of 8.5%. The chemical composition by weight, determined by analysis, is as follows: AI2O3: 8.00% Ca2 +: 0.75% Na *: 3.05% Cl-: 10.68% SO42-: 0.85% water: 76.7% calculated by difference.

The reaction established from the reagents and by analysis of the finished products is as follows: Al (0H)? 29Cl? .7l + 0.12 Ca (0H) 2 + 0.738 NaOH + 0.056 Na2SO4 A1 (0H) 2. ? oClo.78 (SO4) o.?56 + 0.12 CaCl2 + 0.85 NaCl resulting in a basicity of 2.05 / 3 = 68.5% EXAMPLE 14 (In accordance with the invention) 500 g of basic aluminum polychloride are introduced into a 2 liter reactor. This polychloride contains 18.33% aluminum based on AI2O3, 21.78% chloride and has a basicity of 43.1%. S? Empirical formula is: Al (0H)? 29Cl? .7i. 168.8 g of a NaOH solution containing 6 rnoles of NaOH / 1 ee diluted with 200 g of water. It is preheated to 50 ° C and then added for 20 minutes with vigorous turbulence, to the reactor containing the polychloride maintained at 50 ° C. 19.2 g of Ca (0H) 2 are then added to the reactor containing the polychloride and the NaOH solution is maintained at 50 ° C. The addition time is 45 minutes with Rushton type agitation set at 800 revolutions per minute. At the end of the baeification, the stirring speed is reduced to 200 revolutions per minute and the mixture is then allowed to stir for 10 minutes. The temperature is brought from 50 ° C to 70 ° C for 25 minutes, after which it is cooked for 2 hours at 70 ° C with agitation set at 200 revolutions per minute. The product is cooled to 40 ° C for 30 minutes and then clarified by filtration. The recovered filtrate is diluted by adding water to obtain a density of 1,202, ie a content by weight of alumina of 8.5%. The chemical composition by weight, determined by analysis, is as follows: AI2O3: 8.51% Ca2 +: 0.92% Na +: 2.30% Cl-: 10.04% ?? 42 ~: 1.18% water: 77.0% calculated by difference. The reaction established from the reagents and by analysis of the finished products is as follows: Al (0H)? 29Cl? .7i + 0.14 Ca (0H) 2 + 0.452 NaOH + 0.074 Na2 SO4 Al (OH) 2. 3Clo.ß2 (SO4) o.?74 + 0.14 CaCl? + 0.60 NaCl resulting in a basicity of 2.03 / 3 = 67.7% EXAMPLE 15 (In accordance with the invention) 500 g of a basic aluminum polychloride are introduced into a 2 liter reactor. This polychloride contains 18. 54% aluminum based on AI2 O3, 21. 78% chloride and have a basicity of 43.7%. Its empirical formula is: Al (0H)? 29Cl? .7i. 7.7 g of Ca (0H) 2 s are added after the reactor containing the polychloride maintained at 50 ° C. The addition time ee of 20 minutes with Rushton type stirring adjusted to 800 rev / rnin. A basic solution of sodium carbonate and sodium sulfate is prepared according to the following procedure. 1.1 g of sulfuric acid at a concentration of 77, .1% by mass are poured into a sodium carbonate solution containing 76.1 g of Na2C? 3-H2? and 30Q g of water. This basic solution preheated to 50 ° C is added with vigorous turbulence, to the reactor containing the polychloride and Ca (0H) 2 maintained at 50 ° C, for 30 minutes. At the end of the basification ,. The stirring speed is reduced to 200 revolutions per minute. The filter cake of 20 g of solid gypsum CaS? 4-2H2? recovered from several identical tests to Example 1 is added to the reactor as a reagent to saturate the solution. An additional 10 g of gypsum are added according to example 1 and the temperature is brought from 50 ° C to 85 ° C for 30 minutes, then cooking is carried out for 1 hour at 85 ° C, with stirring adjusted to 200 revolutions per hour. minute. The product is cooled to 40 ° C for 30 minutes and then filtered. The filtered gypsum, 8 g, can then be recirculated again.

The recovered filtrate, which gives a titre of approximately 9% alumina, is diluted by adding water haeta to obtain a density of 1,202, ie, a content by weight of alumina of 8.5%. The chemical composition by weight determined by analysis is as follows : AI2O3: 8.47% C, 2+: 0.88% Na +: 2.40% Cl-: 10.05% SO42-: 1.25% water: 77.0% calculated by difference. The reaction established from the reactants and by an analysis of the finished products is as follows: RH0H)? 2? Cl? .71 + 0.059 Ca (0H) 2 + 0.071 CaSO * + 0.0066 Na2S? 4 + 0.308 Na2C03 + 0.308 H20 Al (OH) 2.? 3Clo.8l (SO4) o.?78 * • 0.13 CaCl2 + 0.630 NaCl + 0.308 CO2 resulting in a basicity of 2.03 / 3 = 67.7% EXAMPLE 16 (Not in accordance with the invention) According to example No. 1 of Canadian patent application No. 2,109,756. 350. 6 g of basic polyaluminium chloride PAC 5/6 are placed in a 1 liter reactor equipped with a stirrer and a condenser. The PAC contains 12.39 aluminum and 8.27 chloride, that is, Al (OH) 2.49Clo.s? . The solution is heated to 80 ° C and 20 ° Baurné hydrochloric acid are then emptied over a period of 7 minutes. Acid density 1.16 at 20 ° C contains HCl at 32.14% by weight. The temperature is increased to 95 ° C and then maintained for 1 hour with continuous agitation. The temperature is then reduced to B5 ° C. The composition of the reaction medium is as follows: AI2O3: 8.32% Cl-: 11.96% q? E corresponds to the formula Al (0H) 0.93Cl2.06 and a basicity of 0.93 / 3 = 31% 31.3 g of 60 ° Baume of sulfuric acid are added for a period of 12 minutes. Sulfuric acid has a density of 1.71 at 15 ° C and contains 78.5% H2SO4. The temperature is maintained at 85 ° C for an additional 30 minutes. The heating is stopped and the solution is allowed to cool to 40 ° C for 2 hours. The agitation continues. 280.6 g of water are then added with stirring at 40 ° C. The solution is clear, without precipitate and stable for 30 days. Its chemical composition by weight, determined by analysis, is as follows: AI2 O3: 5. 24% Cl-: 7. 39% S? 42 ~: 3. 06% corresponding to the formula Al (OH)? 35Cl2.06 (S? 2-)? 31 resulting in a basicity of 0.35 / 3-11.7%, while in the Canadian patent application, the next composition in final weight: AI2O3: 10.36% Cl-: 8.84% SO42-: 2.93% equivalent to the formula Al (0H) l.47Cll.23 (S? 42") 0.15 equivalent to a basicity of 1.47 / 3 = 49 % EXAMPLE 17 (Not in accordance with the invention) The process is carried out according to the conditions of Example 4 of Patent FR 2,317,227, with the following reagents: 500 g of a basic polyaluninium chloride are introduced into a 2 liter reactor. The polychloride contains 16. 58% aluminum based on AI2O3, 22.24% chloride and has a basicity of 43.7%. S? Empirical formula is: Al (0H) l.07Cll.93 - The polychloride is heated to 30 ° C with Rushton type stirring adjusted to 200 rev / min. A basic solution of sodium carbonate is manufactured according to the following procedure: 44.29 g of a2C? 3-H2? they are introduced in 141 g of water. This basic solution preheated to 30 ° C is added for 1 hour with vigorous turbulence in the reactor containing the polychloride maintained at 30 ° C. 88.9 g of hydrated sodium sulfate a2S? 4-10H2? they are introduced into the reactor for 10 minutes and the stirring is then continued for 3 hours. The density is 1,289. The chemical composition by weight, determined by analysis, is as follows: AI2O3: 10.74% Na +: 3.70% Cl-: .1.4.50% SO42-: 3.52% water: 67.54% calculated by difference. The stabilized reaction of the reagents and by analysis of the finished products is as follows: Al (0H)? 07Cl? .93 + 18 Na2S? 4 + 0.38 Na2C03 + 0.38 H20 - > Al (OH)? 48Cl?.? 8 (S? 4) o.l7 + 0.76 NaCl + 0.38 C02 resulting in a weak basicity of 1. 48/3 = 49. 3% . The product manufactured earlier can be written in the form of fll (0H)? .48Cl? . 94 (SO4) o. 17 Nao. 76, which is in accordance with the product described in patent 2, 317, 227 having the following formula: Al (OH)? . 8CI1.95 (SO4) o. ís ao .73 - EXAMPLE 18 (Not in accordance with the invention) If the product obtained according to example 17, where said product does not contain a basic compound of an alkaline earth metal, is baked at 80 ° C for 20 minutes, it is observed that the obtained PACS solutions are not stable with time, either at room temperature or at 45 ° C. A large quantity of solids are deposited in the bottom of the flasks. Before comparing, in a table as to all the results of the test of applications in water treatment of the products of the previous examples, ee describe methods to evaluate the products.

MEASUREMENT OF LR RESIDUAL TURBIDITY A PACS obtained according to the EP patent 327,419 will be used as a reference point, leading to a gypsum effluent of 350 kg per ton of PACS, and having the following chemical formula by weight: AI2O3: 8.5% Ca2 +: 1.23% Cl-: 6.44% S042": 1.53% Basicity of 69.6% 20 liters of water from the Seine River are introduced into a 30-liter tank on the eve of the measurement to allow the water to reach room temperature.This water contains the following salts: Na2S? 4, NaHCO3, CaCl2 MgCl2 - It is kept under constant agitation at 100 revolutions per minute.The following amounts of salt (expressed in rng) are in a liter of this water: This water has a turbidity of 9 to 10 NTU and a pH of 8.2 to 8.5. The tests are carried out in a hydrochlorination flocculator (from Orchidis) in the following manner: - introduce in each 1-liter flask flask water from the Seine River, stirred at 100 revolutions per minute, - prepare solutions of the PACS samples to be tested and the reference product, at a dilution of approximately one hundredth of the products obtained in demineralized water, followed by letting the solutions stand for 1 hour, ie 2.94 g of reference PACS giving a title of AI2O3 at 8.5% introduced in the 250 ml flask made with water, the solutions are stable under dilution for at least 2 hours. collect the required quantities of product, 3 rnl, with syringes (solutions diluted to 1 cent, giving a titre of 1 g / 1 of AI2O3), increase the flocculation agitation speed- at 160 revolutions per minute; - inject the products, ie 3 rng based on AI2O3 per liter of water from the Seine River, in the flasks of "bottle test", - start the timer and count 1 minute 30 seconds until the end of the injection, - after stirring rapidly for 1 minute 30 seconds, the speed of agitation is slower at 40 revolutions per minute, - after 13 minutes for 30 seconds at 40 revolutions per minute, stirring is stopped and the agitator blades are lifted, - after sedimenting for 20 minutes, a peristaltic pump extraction tube is introduced into each flask at a depth of 5 cm below the surface and the center of the flask. The pump is turned on and approximately 40 rnl are removed. The extraction speed of the pump is adjusted in such a way that the extraction time does not exceed 30 minutes.

These samples will be attempted to measure residual turbidity. The measurement becomes a Ratio / XR Hach Tyridity Gauge. The results are expressed in NTU (Nephew Turbidity Unit), correlating this unit with the residual amount of particles in the treated water. They carry out four tests. The turbidity value TP, or Tr for the reference PACS, is measured for each test and for each product and the difference in the turbidity elimination is expressed after according to the following relationship: NTU average in% = average of (Tp) ? to4 / Tr? to4) x 100 standard deviation as a percentage of the sum of the relations (Tp? to4 / Tr? to4) x 100.

MEASUREMENT OF RESIDUAL ALUMINUM This test is carried out on the samples after being allowed to stand for 20 minutes. The supernatant solutions are filtered through 0.45 micron pulp membranes. The addition of Ultra-Pur concentrated nitric acid drop avoids any precipitation of aluminum. The measurement is taken by electrothermal atomic absorption, NFT 90-119 1993. The unit is ug / 1. The residual content of aluminum Alp or Air for the reference PACS, is measured for each test and for each product and the difference in residual aluminum content is then expressed according to the following relationship: Average Air * in% = average of (Alp? To4 / Alpto4) * 100 standard deviation as a percentage of the sum of the relations (Alp? To4 / Alr? To) x 100 STABILITY AT 40 ° C This stability occurs in relation to the appearance of solid at the bottom of the flasks, either in crystalline form or in cloudy form with a scaly deposit. It must be at least a month.

STABILITY R AMBIENT TEMPERATURE This stability is given in relation to the appearance of solid at the bottom of the flasks. It must be at least 3 months. Stabilities are determined in PACS solutions having a weight amount of AI2O3 at least equal to 8%. The results are compared in the following table. In the box: - NA: example not according to the invention. - NTU (%) represents the NTU in% according to the aforementioned relationship. - Air § • (%) represents the Alr «« in average% according to the aforementioned relationship. ++++ means very big. +++ means average ++ means deficient + means very deficient.

It is seen that the products obtained according to the present invention (examples 1 to 5 and 7 to 15): - are stable (> 3 months at room temperature and> 1 month at 40 ° C), - make it possible to obtain water treated that have a residual aluminum concentration of less than 125% of PACS reference, and - allow a foculation efficiency of less than 125% relative to the reference PACS.

Claims (19)

NOVELTY OF LR INVENTION CLAIMS
1. I. - A process for the preparation of high basicity polyaluminium chlorosulfate, having the general formula: Al (0H) aClbYc / dM'Cl2 (eM "Cl (I) in which Y represents a valence anion 2, such as SO42-M 'represents a valence cation 2, such as an alkaline earth metal, M "represents a valence cation 1, such co or an alkali metal or ammonium, a, b, c and d are positive non-zero integers or fractions positive and can be zero or a positive integer or positive fraction such that 1.8 < a < 2.25 0.001 < c < 0.150 b = 3 -2c- a &2d + e + b < 3, and q? e have a basicity 0 between 60% and 75%, this basicity being defined by the formula ß = 100 x (3A1 + 2M '+ M "- 2Y - CD / 3A1 in which Al, M' M", Y and Cl they are expressed in rnoles, and said process consists in placing a basic composition of an alkali metal, preferably in aqueous solution, and at least one basic compound of an alkaline earth metal or a metal halide. alkaline earth, in aqueous or powder suspension, in the presence of sulphate ions, in contact with a basic solution of aluminum chloride of the formula: AMOHECÍ ,, (II) in which x is a number between 0.1 and 1.5 ey = 3- x, at a temperature between room temperature (approximately 25 ° C) and 70 ° C, said process being characterized because after basification, the obtained reaction medium is cooked at a temperature, known as the cooking temperature, between 60 ° C and 95 ° C, in such a way that the cooking time is between 3 hours and 20 hours, and preferably between 5 hours and 9 hours for a cooking temperature of 60 ° C and in such a way that the cooking time is between 5 minutes and 15 minutes, and preferably between 7 minutes and 10 minutes, for a cooking temperature of 95 ° C.
2. 2. A method according to claim 1, further characterized in that for a cooking temperature of 60 ° C, the cooking time is between 5 hours and 9 hours.
3. 3. A process according to claim 1, further characterized in that for a cooking temperature of 95 ° C, the cooking time is between 7 minutes and 10 minutes.
4. 4. A method according to claim 1, further characterized in that for a cooking temperature of 70 ° C, the cooking time is between 1 hour and 5 hours.
5. 5. A method according to claim 1, further characterized in that for a cooking temperature of 70 ° C, the cooking time is between 1 hour and 4 hours.
6. 6. - A method according to claim 1, further characterized in that for a cooking temperature of 80 ° C the cooking time is between 10 minutes and 1 hour 45 minutes.
7. 7. A process according to claim 6, further characterized in that for a cooking temperature of 80 ° C, the cooking time is between 30 minutes and 1 hour 30 minutes.
8. 8. A method according to claim 1, further characterized in that for a cooking temperature of 85 ° C, the cooking time is between 10 minutes and 1 hour 45 minutes.
9. 9. A process according to claim 8, further characterized in that for a cooking temperature of 85 ° C, the cooking time is between 30 minutes and 1 hour.
10. 10. - A method according to claim 1 further characterized in that for a cooking temperature of 90 ° C, the cooking time is between 5 minutes and 45 minutes.
11. 11. A method according to claim 10, further characterized in that for a cooking temperature of 9D ° C, the cooking time is between 7 minutes and 10 minutes.
12. 12. A process according to claim 1, further characterized in that the basic compound of an alkali metal is chosen from NaOH, KOH, NaHC? 3, a2C? 3, K2CO3, KHCO3,. and mixtures of at least two of the basic compounds of an alkali metal listed above.
13. 13. A method according to claim 12, further characterized in that the basic compound of an alkali metal is NaOH or Na 2 C 3.
14. 14. A process according to claim 1, further characterized in that the basic compound of an alkaline earth metal is chosen from CaO, MgO, Ca (0H) 2, Mg (0H) 2, CaCO3, and mixtures of at least two of the basic compounds of a previously listed alkaline earth metal.
15. 15. A process according to claim 14, further characterized in that the alkaline earth metal basic compound is Ca (0H) 2, Mg (0H) 2 or MgO.
16. 16. A process according to claim 1, further characterized in that the halide of an alkaline earth metal is CaCl 2 or MgCl 2.
17. 17. A process according to claim 14, further characterized in that the halide of an alkaline earth metal is CaCl2-
18. 18. A process according to claim 1, further characterized in that the basicity ß of the polyaluminium chlorosulfate of high basicity of the formula (I) is between 65% and 70%.
19. 19. The application of high basicity polyaluminium chlorosulfates of the formula (I) obtained in accordance with any of claims 1 to 18 for the treatment of drinking water.