FR2534897A1 - PROCESS FOR THE PRODUCTION OF BASIC ALUMINUM CHLOROSULFATES - Google Patents

Abstract

BASIC ALUMINUM CHLOROSULPHATE MANUFACTURING PROCESS THAT MEETS THE GENERAL FORMULA: (CF DRAWING IN BOPI) IN WHICH: -3N-M-2P3N IS BETWEEN 0.4 AND 0.7 -P IS BETWEEN 0.04 AND 0 , 25N; ET -MP IS INCLUDED BETWEEN 8 AND 35, Z BEING 1CONSISTENT IN REACTING BASIC ALUMINUM CHLORIDE ON BASIC ALUMINUM SULPHATE, PREVIOUSLY WARMED, AT A TEMPERATURE BETWEEN 80 AND 120C, THE RELATIVE PROPORTIONS OF THE CONSTITUENTS BEING CHOSEN SO AS TO OBTAIN A PRODUCT THAT MEETS FORMULA I ABOVE. THE BASIC ALUMINUM CHLOROSULFATES PREPARED ACCORDING TO THE INVENTION FIND AN APPLICATION ESPECIALLY IN WATER TREATMENT. THE PROCESS OF THE PRESENT INVENTION DOES NOT LEAD TO AN BYPRODUCTION OF CALCIUM SULPHATE, CONTRARY TO THE USUAL PROCESSES USED HILL PRESENT.

Description

The present invention relates to a process for the preparation of salts

  Basic aluminum compounds having the general formula: ## STR1 ## the basicity of aluminum chlorosulfate, defined by the ratio of 3 nm to 2 μm, is between 40 and 70% 3 n These products are generally aqueous solutions of concentration 1 to 35 moles of alumina per liter, but they can also be in solid form more or less hydrated, containing more than 30% by weight

of soluble alumina.

  These basic aluminum chlorosulfates find an application especially for the purification of water

  It has been proposed to prepare chlorosulphates

  The hydrosolate is attacked by a mixture of hydrochloric acid and sulfuric acid and the neutral chlorosulfate is brought to the desired basicity by partial neutralization and consolidated by means of carbonate, hydroxide or alkaline bicarbonate. (FR 2 036 685)

  this type of process actually makes it possible to prepare

  posed the most appropriate, but has the disadvantage of

  produce a significant amount of alkaline sulphate

  earthy, calcium for example, which poses pollution problems. There are other variants of the above process, where the chloride ion is brought by calcium chloride and not in the form of hydrochloric acid (FR 2 281 895): the

  Effluent problem is further amplified.

  That's why he was tempted to make up for this

  the defect of the prior art by performing the step of basification

i 5 34897

  different way: chiorosulphate or chloride of

  luminium is treated with aluminum metal powder.

  This process, in addition to the economic disadvantage

  use of aluminum powder, does not make it possible to obtain the basic salts having the desired polymeric structure for the

water treatment.

  Finally, a process has been proposed which carries out the basification by carrying under pressure and at a temperature of 170 [deg.] C. a mixture of aluminum chloride, aluminum hydroxide and sulfuric acid, optionally recycling

  unreacted surplus products (FR 2 125 337).

  This way of operating is close to the already known technique

  of basification consisting in attacking with hydrochloric acid

  excess hydrargillite, this reaction being

  also under pressure to accelerate its kinetics (FR 2 174 114).

  This procedure makes it necessary to add the sulfuric acid before the basification phase to obtain a basic chlorosulphate having a better efficiency in the treatment of water compared to a similar basified salt in the absence

of sulfuric acid.

  However, it was discovered quite unexpectedly.

  in the applicant's laboratories that it was possible to prepare a basic aluminum chlorosulfate having such good characteristics for the treatment of water by carrying out the basification stage under pressure in the absence of sulfuric acid, unlike what were left

  assume the data of the prior art.

  It was surprising to find that after having dissolved the aluminum hydroxide in a concentrated solution of aluminum chloride by operating under pressure, the reaction mixture can be stabilized, that is to say, keep in solution the basic chloride of aluminum, by adding a

  more dilute solution of slightly basic aluminum sulphate

  than; to achieve this stabilization, we operate in the same way

2.534897

  following: after bringing back the supersaturated solution of chlorine

  basic aluminum oxide at its boiling point at

  atmospheric pressure adds a frankly

  coated with basic aluminum sulphate obtained by attacking an excess of aluminum hydroxide with sulfuric acid at atmospheric pressure, the latter solution being at a

  temperature as close as possible to that of the chloride

  if that. The present invention thus provides a process for producing basic aluminum chlorosulfate having the general formula: ## STR1 ## wherein: N-m is between 0.4 and 0.7, 3 np is between 0.04 and 0.25 N and m / p is between 8 and 35, z being> 1 consisting of reacting basic aluminum chloride on basic aluminum sulphate, previously

  when hot, at a temperature between 80 and 120 OC.

  The reaction is rapid: the duration of the reaction is usually

  between a few minutes and an hour.

  The relative proportions of the constituents are determined so as to obtain a product having the formula

(I) above.

  The basic aluminum chloride used can

  The present invention may be obtained by any suitable means. It may in particular be obtained in the following manner known per se: hydrochloric acid is reacted with alumina in such proportions that, after reaction, a solution of chloride is obtained. of aluminum close to supersaturation, this solution is then reacted with aluminum hydroxide in excess of 10 to 150% relative to the theoretical amount necessary for the desired basicity, in a stirred medium for a maximum of 5 hours. hours, at a temperature of 140 165 O under a pressure of 0.5 to 3 bars. Basic aluminum sulphate usable according to

  the present invention may be prepared by any suitable means

  It can in particular be prepared in the following manner known per se: is added to a sulfuric acid solution% O of aluminum hydroxide in excess of 10 to 100% relative to

  at the stoichiometry of the neutral sulphate, the suspension is heated

  obtained and kept at boiling for 15 minutes.

at 30 minutes.

  In a more detailed way the implementation of the

  process, which may be continuous or discontinuous, may be

  read in the following way: it is introduced into a reactor

  agitated hydrochloric acid having a weighted concentration

  equal to or greater than 30%, and preferably 33%, as well as aluminum hydroxide (eg hydrargillite) in

  such proportions that, after reaction, a solution is obtained

  aluminum chloride which is close to saturation;

  the solution is then transferred, which may contain hy-

  aluminum hydroxide in suspension if the previous reaction was carried out with an excess of this reagent, in a reactor

  pressure-resistant or the introduction of hy-

  aluminum oxide so as to have an excess of 10 to 150%

  and preferably 70 to 120% with respect to the theo-

  necessary for the desired basicity.

  stirred for up to 5 hours, but preferably 2 to 3 hours depending on the fineness of the hydroxide used, at a temperature of

  1 = 650 ° C. and under a pressure of 0.5 to 3 bars; these

  operational procedures make it possible to obtain maximum disso-

  elution of aluminum hydroxide The reaction mixture

  is then brought back to atmospheric pressure, the temperature

t 534897

  ture then being 120 1250 C according to the initial concentrations

  the degree of dissolution of the hydroxide and

the water content of the latter.

  Simultaneously with basification of

  luminium, the synthesis of aluminum sulphate

  basic to stabilize the basic chloride at a

  In the case of sulfuric acid, aluminum hydroxide is added in excess of 10 to 100% and preferably 30 to 70% relative to the stoichiometry of the neutral sulphate and the suspension obtained is heated and then boiled for 15 to 15 minutes. 30 minutes; this duration is variable according to the fineness of the hydroxide used After dilution with water for

  to fluidify the reaction medium, this aluminum sulphate

  The most basic alkyds, whose temperature is then between 70 and 1000.degree. C., are cast in basic aluminum chloride, the temperature of which is 120.degree.125.degree. C., in proportions such that the chlorosulfate obtained has the general formula: IA (OH) 2 c (SO) 1 Ln 3 nm 2 pm 4 p IZ in which, n, m and p where the meanings above and

z is> 1.

  In order to ensure maximum dissolution of the

  aluminum hydroxide solution in the aluminum chloride solution, it is necessary to add an excess of about 100%, in one

  or several times, grains of less than 30

  Crons preferentially contributing by dissolving to basify the reaction medium. The aluminum hydroxide which has not reacted is recovered during the filtration which delivers the solution.

  final chlorosulfate basic; following the excess nis in

  its quantity may be sufficient to make a new

  The solution is then rendered basic with nine hydroxide added in excess,

in one or more times.

  This excess quantity may vary between 10 and 150% and preferably 70 and 120% depending on the reactivity

  and the moisture of the hydroxide In fact a very human hydroxide

  mide added in excess is to dilute the solution

  aluminum chloride and reduce its boiling point.

  lition, therefore of attack which must then be compensated by a

  pressure increase of the agitated autoclave.

  After stabilization of the basic chloride with the sulfate solution, the basic chlorosulfate is diluted, cooled, filtered to remove the excess hydroxide next

  techniques known to those skilled in the art.

  The aluminum hydroxide used in the

  assigned according to the invention may have different origins, it may be a freshly prepared hydroxide, but it will be used

  preferably, for economic reasons, hydrargill-

  lite from the Bayer Alumina Extraction Process at

  bauxite shot, in wet form (35% water content) or in dry form Depending on the acceptable levels of impurities, it is also possible to directly use an alumina ore, for example bauxite or after

prior calcination.

  The examples below illustrate the invention

without limiting it.

i

EXAMPLE 1

  In a stirred reactor 550 g of acid were poured

  40% hydrochloric acid (density 1,198) on 162 g of hydrated alumina

  wet end grading 62.8% of A 1203 After braking

  ballooning of the reaction through a means of heating-

  cooling to maintain the temperature at 60 C, heated gradually to 105 C, and then poured 324 g wet hydrated alumina Continuing to heat,

34897

  it boils at 123 ° C. at atmospheric pressure: the reactor is then placed under an air pressure of 1.2 bar, while boiling is restored at the moment when the reactor temperature reaches 147 ° C. heating to keep boiling starting for 3 hours. Despite the excess of hydrated alumina, no thickening of the suspension would occur.

  to a precipitation of basic chloride We stop the heating

  fuse, slowly breaks the pressure up to the pressure

  mospheric and poured while stirring a hot solution (about 80 90 C) of basic sulfate prepared as follows: 91 g of sulfuric acid 70 T% are poured on 55 g of hydrated alumina is boiled for 15 minutes while stirring, pour 30 g of cold water, then 220 g of water

hot dilution.

  The contents of the 1-liter reactor are transferred to a stirred 2-liter vessel. 700 g of water are then poured in at 40 ° C., the mixture is stirred for 15 minutes to cool to 40 ° C. and the suspension is filtered. In less than 12 minutes, 1895 g are collected. of solution of density 1,225 at 200 C which is diluted with 136 g of water to reduce the density to 1.206 The solid residue weighs

  207 g, 57% A 1203 and 2.0% chlorine ion.

  consisting of excess alumina and imbibition solution. Density solution 1,206 grade 10.0% ion

  chlorine, 10.5% alumina and 3.0% total sulfate ion.

EXAMPLE 2

  In 550 g of 40% hydrochloric acid,

  184 g of the above residue to make the chlorine solution

  aluminum hydroxide, and basified as before with 324 g of moist hydrated alumina while maintaining for 3 hours at

boiling at 146 ° C. under 1.2 bar.

  In addition, the basic sulfate is prepared with

  the residue residue to which 43 g of hydrated alumina is added.

  After boiling, dilute with 30 g of cold water and 220 g

  of water brought to 90 ° C., this suspension is poured into the solution.

  The solution was then diluted with 830 g of water at 40 ° C. Filtration produced 200 g of residue containing 57.7% of A 1203 with 1.93% of chlorine ion and 2050 g of sodium chloride solution. density 1.213 which is brought back to a density equal to 1.206 with 58 g of water The 2108 g of final solution contains 9.95% of chlorine ion, 10.6% of A 1203 and 3.0% of ion SO 504

23 4

  As can be seen, we arrive at a complete consumption of alumina while manufacturing solutions of basic chlorosulphate of aluminum, whereas in some processes of neutralization with lime or calcium carbonate, the portion unaccounted for 1050 C in acid medium

  hydrochloric acid + sulfuric acid is lost with the remaining

brant of gypsum formed.

Claims (3)

  1 Process for producing basic aluminum chlorosulfate   nium corresponding to the general formula: lAin (OH) 3 nm_ 2 p Cl (SO 4 p () in which: 3 nm-2 p is between -0.4 and 0.73 np is between 0.04 and 0.925 N and _-m / p is between 8 and 35, z 6 as> 1 consisting in reacting basic aluminum chloride with basic aluminum sulphate, previously heated, at a temperature of between 80 and 80.degree. 120 C, the relative proportions of the constituents being chosen so as to obtain   a product of formula (I) above.   The process according to claim 1 wherein said chlorine   Basic aluminum oxide is obtained by reaction of hydrochloric acid on alumina in such proportions that after reaction we obtain a solution of aluminum chloride   substantially supersaturated, followed by the reaction of this solu-   of aluminum chloride with aluminum hydroxide being in excess of 10 to 150% in excess of the theoretical amount required for the desired basicity, in stirring medium for a maximum of 5 hours, at a temperature of   at 165 ° C. under a pressure of 0.5 to 3 bars. <2534897 Ji IOQ   3. Method according to one of claims i or 2 in the-   which said basic aluminum sulphate is obtained by reaction   sulfuric acid on aluminum hydroxide in excess of 10 to 100% with respect to the stoichiometry of the neutral sulphate, the solution being heated and then kept at the boiling point. lition for 15 to 30 minutes.