CA1103124A - Preparation of aqueous suspensions of finely-divided water-insoluble silicate cation-exchangers - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A method for the preparation of finely-divided water-insoluble calcium-binding aluminosilicate suspensions suitable for detergent formulations comprising 1) mixing an aqueous alkali metal aluminate solution with an aqueous alkali metal silicate solution in the presence of an excess of alkali to give a silicate compound having a calcium-binding power of at least 50 mg CaO/gm of anhydrous active substance and having the formula, combined water not shown:
(M2O)0.8-1.3 ? Al2O3 ? (SiO2)1.75-2.0 wherein M represents an alkali metal, wherein said aqueous solutions have a composition corresponding to the desired Al2O3 and SiO amounts of the above formula, with at least 2.5 mols M2O/mol Al2O3 and not more than 80 mols H2O/mol Al2O3, rapidly with vigorous agitation, 2) agitating the mixture vigorously while continuing said mixing until the mixture viscosity of the aqueous mixture has been passed but the minimum viscosity has not yet been reached, 3) then homogenizing said mixture at least once by recycling and until said mixing step is completed, 4) maintaining the homogenized aqueous suspension at an elevated temperature until formation of at least some aluminosilicate crystals, and 5) recovering said aluminosilicate suspensions.

Description

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~ he invention concerns a method of preparing aqueous suspensions of finely divided, water-insoluble aluminosilicates containing bound water and capable of ex-changing cations, which are suitable for processing to wash-ing and cleaniny agents, of the general formula (M20)o 8-1 3 A123 (Si2)1.75-2.0 (I) wherein M denotes an alkali metal cation. The invention con-cerns, furthermore, the suspensions obtained according to this method and their use particularly for the production of washing and cleaning agents.
The compounds of the general formula I are capable of exchanging cations with the hardness formers of waterl that is magnesium and calcium ions. Their calcium binding power is generally above 50 mg CaO/gm of active substance (AS), and preferably in the range of 100 to 200 mg CaO/gm,~AS.
The calcium binding power can be determined according to the method indicated in the examples. By "active subs-tance" (AS) the solid obtained after drying for 1 hour at 800C. is meant.
The above-described water-insoluble alumino-silicates are of, particular interest as ingredients of wash-ing and cleaning agents since they are capable of partly or completely replacing the phosphate builder substances present-ly used today.
Aluminosilicates of the above-indicated formula which are capable of exchanging cations are known compounds.

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They are generally synthesi~ed by preparing an aqueous mixture consistin~ of the calculated amounts of A12O3 and SiO2 in the indicated ratio and M20 and water by combining solutions of the individual components. Mostly solutions of alkali metal a:Luminate and alkali metal silicate are used as the starting materials.
A number of various methods of preparing such compounds within the above-outlined framework are already known. But there is still a need for a method which provides aluminosilicates of the above-indicated formula with a part-icularly short reaction time and high space-time yield, which are extremely finely-divided and have a narrow particle size spectrum or range.
OBJECTS OF THE INVENTION
An object of the present invention is the devel-opment of a method for the preparation of finely-divided water-insoluble calcium-binding aluminosilicate suspensions suitable for detergent formulations comprising 1) mixing an aqueous alkali metal aluminate solution with an aqueous alkali metal silicate solution in the presence of an excess of alkali to give a silicate compound having a calcium-binding power of at least 50 mg CaO/gm of anhydrous active substance and having theformula, combined water not shown:

(M20)o 8 1 3 A123 (Sio2)l.75-2.o wherein M represents an alkali metal, wherein said aqueous solutions have a composition corresponding to the desired A12O3 and Si02 amounts of the above formula, with at least

2.5 mols M20/mol A12O3 and not more than 80 mols H2O/mol A12O3, rapidly with vigorous agitation, 2) agitating the

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mixture vigorously while continui.ny said mixiny until the maximum viscosity of the a~ueous mixture has been passed but the minimum viscosity has not yet been reached, 3) then h~omogenlzing said mi~ture at least once by recycling and ~mtil said mixing step .is completed, 4) maintaining the homogenized aqueous suspension at an elevated temperature until formation of at least some aluminosilicate crystals, and 5) recovering said aluminosilicate suspensions.
A further object of the present invention is the obtaining of finely-divided, water-insoluble, calcium-binding aluminosilicate suspensions by the above method.
Another object of the present invention is the developing of a process for the production of washing agent compositions employing said finely-divided, water-insoluble, calcium-binding aluminosilicate suspensions.
These and other objects of the invention will become more apparent as the description thereof proceeds.
DESCRIPTION OF THE INVENTION
The subject of the invention is a method of pre-paring the above-mentioned compounds which are called here-after "aluminosilicates" for short, by mixing an alkali metal aluminate dissolved in water with an alkali metal silicate dissolved in water in the presence of excess alkali, which is characterized in that the aqueous solutions, whose calculated total composition regarding their A1203 and their Si02 con-tent corresponds to the above-indicated Formula I, and par-ticularly to the composition of the desired product, but which contain altogether at least 2.5 mols of M20 per mol

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A1203 and at most 80 mols of water per mol A1203, as con-t:ained in Formula I, are mixed rapidly under vigorous stir-ring, and that the suspension obtained, optionally before the solutions are completely combined, are further stirred Vigorously at least until its maximum viscosity has been passed, bu-t the minimum viscosity has not yet been reached, after which they are recycled through a homogenizer at least oncej but at least until the solutions are completely mixed, and are then kept at an elevated temperature until they at least partly crystallize. The suspensions can subsequently be adjusted to a pH value of below 12.5 by partly washing out the excess alkali, removing at least a part of the ad-hering mother liquor and replacing it at least partly by water and/or by the addition of an acid.
More particularly, the invention relates to a method for the preparation of finely-divided water-insoluble calcium-binding aluminosilicate suspensions suitable for detergent formulations comprising 1) mixing an aqueous alkali metal aluminate solution with an aqueous alkali metal silicate solution in the presence of an excess of alkali to give a silicate compound having a calcium-binding power of at least 50 mg CaO/gm of anhydrous active substance and having the formula, combined water not shown:
(M20)o 8 1 3 A123 (sio2)l.75-2-o wherein M represents an alkali metal, wherein said aqueous solutions have a composition corresponding to the desired A1203 and SiO2 amounts of the above formula, with at least 2.5 mols M20/mol A1203 and not more than 80 mols ~20/mol A1203, rapidly with vigorous agitation, 2) agitating the mixture vigorously while continuing said mixing until the jrc ~?~

maximum viscosity of the aqueous mixture has been passed but the minimum viscosity has not yet been reached, 3) then homogenizing said mixture by recycling the same through a separate homogenizer at least once during a period not later than 60 seconds after said mixing step is completed, 4) maintaining the homogenized aqueous suspension at an elevated temperature until formation of at least some alumino-silicate crystals, and 5) recovering said aluminosilicate suspensions.
The metal cations M in Formula I are the alkali metals, such as lithium, potassium and preferably sodium. The invention will be illustrated below on the basis of the sodium aluminosilicates but the data apply correspondingly also to the aluminosilicates of other catlons.
The composition of the aluminosilicates contained in the Ruspensions prepared according to the invention can be determined by elemental analysis. To this purpose, the aluminosilicates are isolated from the suspension by washing and adjusted to a pH value of 10 (in a suspension containing, for example, 30% by weight of dry substance) and dried until the adhering water is removed. The above-indicated formula comprises both amorphous compounds and more or less crystallized compounds of the same gross composition. The degree of crystallization can likewise be determined in the alumino-silicate, (isolated as described above), by comparing the X-ray diffraction diagrams with fully crystallized samples (maximum intensity of the X-ray diffraction lines).
The order in which the commponents are mixed can vary.
According to a preferred variant of the invention, the mixing of the reaction solutions of sodium a]uminate or sodium silicate, for examp]e, is so effected that some liquld, ~ ,- .i ~ . ! ~, j particularly water or at least a part of the sodium aluminate solution, is first charged into the reaction vessel, and the other reactants are rapidly introduced under stirring. It is advisable to work so that a mathematical A1203 excess exists in the reaction vessel until the solutions of the reactants are all combined with each other. For example, the aluminate solution is charged and the sodium silicate solution is introduced rapidly under stirring. But the re-verse order is likewise possible, for example, b~ diluting first a highly concentrated sodium silicate solution with some water.
On the other hand, it is also possible to charge only a part of the aluminate solution, hencel for example, 10~ more, and to add the balance of the aluminate solution during the reaction of the reaction solutions with each other.
All percentages are percent by weight, unless otherwise ! stated.
Principally, the reaction can be carried out at any temperature but, naturally, the temperature range in which water is liquid at normal pressure is preferred.
Mostly the temperatures are above room temperature.
By increasing the temperature, the reaction can be accelerated, and it is preferred to mix the solution at a ~rc:~

temperature between 55C and 100C, particularly between 60C
and 85OC. The aluminate solution and/or silicate solution is preferably preheated to a temperature in the indicated range.
In general, the sodium alurninate is introduced int-o the reaction system as a solution of sodiurn alumina-te.
The ratio of Na20 : A1203 in the sodium aluminate solution need not necessarily correspond to the formula NaA102. Rather, other ratios of Na20 : A1203 can also be used, provided the synthetic mixture prepared by mixing aluminate solution with the silicate solution has the composition in the indicated range. The ratio Na20/A1203 can thus be higher or lower than 1 in the sodium aluminate solution, where, as a limit, the aluminate can also be used in the form of reactive hydrate, which then transforms the correspondingly enriched alkali in the silicate solution into sodium aluminate during the mixing in situ. In general, the ratio of alkali metal oxide to A1203 in the aluminate solution is above 1.5, for example, in the range between 2.0 and 3.5. The range between 2.0 and 3.2 is mostly preferred.
Correspondinq to the composition of the aluminate solution which isvariable within wide limits, the composition of the silicate solution can also be varied within wide limits.
In general, the silicate is used as water-soluble silicate, e.g., waterglass. Provided that the presence of excess alkali required according to the invention is ensured by the enrich-ment of alkali in the sodium aluminate solution, a low-alkali silicate can also be used. Again, as a limit, reac-tive silica can be mentioned which is transformed under the reaction con-ditions in the synthetic mixture in situ into an alkali metal silicate. Preferably, an alkali metal silicate with a molar ratio of M20 : SiO2 of about 1 : 2.0 to 1 : 4, particularly 1 : 2.2 to 1 : 3.8 is used.
The composition of the synthetic mixtures used jrc:~

according to the lnvention corresponds with regard to the ratio of SiO2 : A1203 mathematically to the ahove-indicated ratio for the suspended aluminosilicates, which is 1.75 : 1 to 2 : ].. The preferred aluminos.ilicates, particularly the pre-ferred sodium aluminosilicates, have frequently ratios of SiO2 : A1203 in the range of 1.8 to 1.9. The composition of the suspended aluminosilicate corresponds with regard to the SiO2/A1203 ratio to the composition of the synthetic mixture; slight variations may be due to the fact that a small amount of unreacted aluminate or silicate is also present, in additio~ to the precipitated aluminosllicate, which is then removed substantially by washing. These are minor deviations, however, and they are mostly in the range of the limit of error of the analytical determinations.
A particularly important parameter is the amount of alkali in the synthetic mixture; it is at least 2.5 mols of alkali metal oxide per mol of A1203. A ratio of 2.8 to 3.8, particularly 3.0 to 3.6 mols of alkali-metal oxide per mol of A1203, is preferred. The calculated Na20 content or alkali metal oxide content in the isolated aluminosilicate is within the indicated range of Formula I, mostly about 0.8 to 1.2, particularly 0.9 to 1.15 mols of Na20 per mol of A1203. Molar ratios of above 4 mols of alkali metal oxide per mol of A1203 are generally no longer of advantage for the purposes of the invention. Preferahly, then, the mixing and reacting solutions should contain from 2.5 to 4 mols of alkali metal oxide per mol of A1203.
Another important parameter is the amount of water present. The water content of the synthetic mixture bein~
mixed should be below about 80 mols of H20 per mol of A1203.
The lower limit of the water content is that of the limit of stirrability, that is, there must be at least so much water present in the synthetic mixture being mixe~ that it can be _ g _ irc l~`~

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stirred in all stages of the process. This lower limit of water in the synthetic mixture can be below 45 mols of water per mol aluminum oxide.
In general, however, a water content on the range between 45 and 75 mols of water per mol of A1203 is preferred.
This range is of particular advantaye when it is important to obtain products which have, in the given composition, the highest possible ion-exchange capacity, for example, the max-imum binding power for the hardness-forming ions of ordinary water. Such products are preferably highly crystalline and have the structure of the so-called zeolite A. Depending on the duration of the crystallation stage, other crystalline and/or amorphous compounds, such as hydrosodalite, can be present, in addition to zeolite. Unless it is important to obtain the highest possible ion-exchange capacity, ratios with less than 45 mols of E120 per mol of A1203 are particularly preEerred in the synthetic mixture to be mixed according to the invention.
~ere a particularly favorable space-time yield with extremely finely-divided particles and absence of agglomeration are obtained. Particularly favorable mixing ratios for the high-est possible exchange capacity (determined as calcium-binding power) are ohtained with molar ratios of ~120/~1203 in the range between 45 : 1 and about 60 : 1.
When mixing the reactants with each other, a water-clear solution is obtained first, which becomes cloudy, however, more or less rapidly depending on the mixing temper-ature, and gelatinous. The viscosity of the reaction mixture being stirred first greatly increases, but then it diminishes when the vigorous stirring is continued. The viscosity course of the reaction mixture can be observed, for example, on the basis of the energy consumption of the stirrer operating at a constant speed.
When the maximum viscosity has been past, the reaction mixture is transferred from the reaction vessel into ~1~3~

a comminution device in which it is subjected to high shearing forces and the viscosity is reduced to its minumum. Prefer-ably, the comminution device is traversed several times, for example, 2 to 7 times, recycling the suspension from the comminution device to the reaction vessel where the reaction solutions, which had not yet been completely added when the suspensions were transferred from the reaction vessel to the comminution device, are now added in doses. Subsequently, the reaction mixture passes again th~ough the comminution device.
As mentioned above, the reaction velocity, that is, the rate of precipitation, depends on the temperature.
The viscosity maximum is thus achieved sooner or later, de-pending on the temperature, and correspondingly, the viscosity will drop faster or slower after the maximum has been attained, depending on the temperature. For the removal of the reaction mixture from the reaction vessel and the transfer to the comminution device, it is preferable tha-t this step is com-menced generally 1 to 120 seconds after the viscosity maximum has been past.
If the mixing of the reactants is effected at temperatures in the range between 55C and 100 C, particularly between 60 C and 85 C, as it is generally preferred, the viscosity maximum of the reaction mixture being vigorously stirred is reached extremely fast, so that it may be advisable under certain circumstances to control the process on the basis of calculated time data for the individual process steps than on the basis of the viscosity control. Thus the reactan-ts are generally mixed with each other within a period of about 3 seconds to 5 minutes, preferably about 3 seconds to 2 minutes, particularly within a period of about ~ to G0 seconds. The maintenance of the suitable reaction condition is ensured if the suspension obtained is recycled through the comminution jrc~
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devlce within about 0 to 120 seconds, preferably a~out 0 to 60 seconds after the calculated amounts of reactants required for the formation of half the anticipated amount of the product have been coml-ined. The treatment in the comminution device is generally continued not later than 60 seconds after the cornplete combination of the reactants.
The comminution devices which are used within the framework of the invention are those devices which are used, for example, to emulsify a liquid, which is not mis-cible by itself with the other liquid, with the latter, or to disperse solids with small particles size to liquids. The phenomena which distinquish the action of the cor~inution device according to the invention from simple stirrers are high shearing forces, cavitation, twist and turbulence. In particular, the comminution devices according to the invention are devices where cavitation occurs in the treatment of li~uids. The proce.ss is a homogenization process or homogeni-zation with cavitation.
An example of a comminution device that can be used according to the invention is a high-pressure homogenizer, where the homogenization process takes place in the so-called homogenizing valves in which the mixture of liquids which is under a high pressure, or the suspension of silicate particles which is under a high pressure accordinq to the invention, expands abruptly in the aqueous medium, hence, is exposed to a much lower èxternal pressure.
The comminution devices used are particularly those which perrnit the treatment of suspension under conditions under which liquids which are not miscible by themselves, like water and benæene, are emulsified with each other, forming, in the absence of surfactants or naturally unstable emulsi-fiers, emulsions with a particle size be-tween 0.1 and 10~.
An example of the above-described homogenizers _ 12 -jrc~

are the commercially availab~e Galllin homogenizers or high-pressure homogeniæers.
Other comminution devices that can be used according to the invention, as homogenizers, are the liquid mixers, which consist of stator and rotor units. An example is the multifrequency liquid mixexs, which consist of a milti~stage system of stator plates and rotor disks, where the stator plates have circular openings through the holes of which the material to be mixed passes in an axial direction.
These openings are arranged deep in annular channels provided symmetrically on both` sides of the stator plates. The flanks of the channels can have specially designed indentations. The likewise annularly arranged shearing pins of the rotor disks run in the channels.
For most applications of ion-exchanging, the aluminosilicates are preferred as crystalline products. Accord-ingly, the suspension is preferably subjected to a crystalliz-ation step, after the recycling of the suspension through a comminution device is completed. This crystallization step consists in keeping the suspension of the water-insoluble aluminosilicate after the homogenization at a temperature of between 50C ana 100C, preferably between 70C and 95C, until the desired, radiographically-de-terminable degree of crystalliæ-ation of the suspended aluminosilicate has been obtained. It has been found advantageous, although by no means necessary, to supply very lïttle or no stirring enerqy during the crystalliz-ation of the suspension. It is of advantage if the crystalliz-ation step is carried out continuously, supplying only so much stirring energy to the suspension, which is thixo-tropic suspen-sion, as is necessary to keep it fluid or conveyable.
The crystallization is also accelerated by a temperature increase. Therefore, it is advisable to raise the temperature at least temporarily above the temperature jrc~

established durin~ the mixing of the aluminate and silicate solutions, for the purpose of the crystallization. Particular-ly suitable for the crystallization step is a method where the temperature of the suspension is raised rapidly to 90C to 95C, for example, hy injectinq steam or by external heating, and either keeping it at this level until the desired degree of crystallization in the suspended aluminosilicate has been achieved, or reducinq it again to a range of between 50C to 90C and keeping it in this range until the desired degree of crystallization has been achieved. The mixing of the aluminate and silicate solutions, which has preceded the crystallization step, can be effected, for example, at 60 C to 70 C.
Within the framework of the crystallization step, the suspensions can also be kept longer at elevated temperature than is necessary to obtain theldesired degree of crystalliz~
ation, when it iLs desirable under certain circumstances to influence other properties of the suspension, for example, the particle-size distribution of the aluminosilicate particles.
The duration of the crystallization step can vary between about 3 m~nutes and several hours. It was found surprisingly that the above-descrihed combination of process steps yields particularly high valuec for the calcium binding power, even at the relatively short crystallization periods. Thus, the duration of the crystallization step is mostly under 2 hours, generally about 5 to 65 minutes.
After the recycling treatment in the comminution device, or, following the crystallization step when followed, the suspension can be cooled. After cooling, the desirable partial neutralization is effected by washing and/or addition of acid. For the purpose of the desirable partial neutralization, the suspension can be freed of at least a part of its content of excess alkali, for example, by washing. To this end the sus-pension is freed of at least a part of the mother liquor, for ~ 14 -jrc~

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example, by centrifug~ng or filtering, after which water is adcled and the now diluted mother liquor is separated again, if necessary. Particularly advantageOus is the technique of dis-plclcement washing. In qeneral, the pH value is adjusted to a value below 12.5. But the suspensions can also be utilized at hiyher pH values to formulate washing and cleaning agents.
Naturally the concentration of the suspension can be influenced during the partial neutralization. Principal-ly, the concentration can naturally be reduced to any desired yalue by adding the required amount of water. A particular advantage of the method accordin~ to the invention, however, is that aluminosilicate particles are obtained which show an unusually fa~orable suspension behavior. It is not only possible to produce suspensions of relatively low concentra-tions with solid contents of 5% to 20% by weight, or suspen-sions having a medium concentration of 2~% to 30% by weight, but also suspensions at pH values of between 7~and 11.5 with a soli~s content in the range of between 30% and about 53% by weight. At this concentration range the advantages achieved with the method according to the invention are par-ticularly obvious, so that, if it is intenaed to dry the sus-pension later and excess water is thus not desired, liquid, readily pumpable suspensions according to the invention with solid contents of over 35%, for example, in the range oE
37% to 50%, can still be used with great advantage. However, the term "suspension" in the sense of the invention also includes aluminosilicate/water mixtures which are no longer pumpable, hence mixtures which have a solids content of up to 60% or even up to 70% by weiqht.
When speaking of "solids content", this refers to the content of compounds o Formula I. The solids content is de ~rmined hy filtering off the aluminosilicates of Formula I, washing them out carefully to a pH value of the wash water jrc~

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of 10, and then drying them for one hour a-t 800C to remove the adhcring water and to determine the anhydrous active substance (AS). A suspension according to the invention with a solids content of 31% by weight, for example, thus contains 31% by weight of a product, isolated and dried as described above but, naturally, products can also be present from the production which are solid in pure form but which are removed during the washing as water-soluble substances.
In general, the pH value is adjusted af-ter the homogenization step and after the optional crystallization step. This can be done, as described, by washing to pH
values below 12.5. However, it was also found advantageous to effect the partial neutralization at least partly by adding acid. For example, the aluminosilicate suspension can be washed out until it has less than 5% excess alkali with a solid concentration of 30% or more, and then be neutralized by adding acid. Preferably, the suspension is washed out to an alkali content of 3% or less, particularly 2% or less. The percentages relate to the total weight of the suspension. The pH value of the suspension is generally between about 6 and 11.5, mostly above 7 and preferably between about 8 and 11.
The free acids which can be used for neutral-ization are particularly the mineral acids, such as sulfuric ` acid, phosphoric acid, or hydrochloric acid. Which acid is used specifically for the neutralization or partial neutral-ization step depends substantially on the intendecl use of the suspension. If the suspension is inten~ed, for example, for the production of aluminosilicate-containing washing and clean-3~ ing agents, sulfuric acid is generally the acid oE choice, since it forms sodium sulfate on neutralization which does not interfere with the washing process.

Local excessive acidification of the suspension ~ 16 -jrc~

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should be avoided durlny the addition of acid since the products are sensitive to free acids. This ~roblem can be controlled, however, since local pH reductions to the ranges where the products are dissolved or damaqed can be preven-ted by viyorous stirring and/or slow addition.
If processing to washiny and cleaning agents is intended, it is also possible and advisable to use a sub-stance whose water-soluble salts have surface activity, hence, washing activity, as the acid of neutralization.
Suitable acids for the neutralization are thus the anionic surface-active compounds or tensides in their acid form, particularly anionic tensides of the type of the sulfates and sulfonates. These tensides contain in the molecule at least one hydrophobic organic radical, mostly an aliphatic hydro-carbon radical with 8 to 26, preferably 8 to 16 aliphatic carbon atoms.
The tensides of the sulfate type include alkyl-benzene sulfonates (Cg 15 alkyl~, mixtures of alkene sul-fonates and hydroxyalkane sulfonates, as well as alkane di- ;
sulfonates, as they are obtained, for example, from mono-olefins with terminal or non-terminal double bond by sulfon-ation with gaseous sulfur trioxide and subsequent alkaline or acid hydrolysis of the sulfonation products. Also suit-able are alkane sulfonates which are obtained from alkanes by sulfochlorination or sulfoxidation and subsequent hydrolysis or neutralization, or by the addition of bisulfite onto olefins. Other suitable surfactants of the sulfonate type are the esters of ~-sulfofatty acids, e.y. the ~-sulfonic acids from hydrogenated methyl o~ ethyl esters of the coconut fatty acids or palm kernel fatty acids or tallow fatty acids.
Other suitable tensides of the sulfate type are the sulfuric monoesters of primary alcohols (e.g. from coconut fatty alcohols, tallow fatty alcohols or oleyl alcohol) and those of jrc~ J

secondary alcohols. Furthermore, sulfated fatty acid alkanol-amides, fatty acid monoglycerides, or reaction products of 1 to 4 mols of ethylene oxide with primary or secondary fatty alcohols or alkylphenols can also be used.
Other suitab]e anionic surface-active compounds which can be used according to the invention in their acid form for the neutralization are the fatty acid esters or fatty acid amides of hydroxy-or amino-carboxylic acids or sulfonic acids, such as fatty acid sarcosides, fatty acid glycolates, fatty acid lactates, fatty acid taurides or fatty acid isoethionates.
The use of anionic tensides in their acid form for the neutralization or partial neutralization of excess alkali is also of advantage insofar as the suspensions thus prepared have a much better suspension stability, which is of consider-able advantage for processing, but also for storage.
Other compounds suitable for stabilizing the sus-pensions, which can be used as free acids and thus for the partial neutralization, naturally also in the form of their salts, are the polymeric, especially synthetic, polycarboxylic acids. Among these are mentioned, in particular, polyacrylic acid and poly-~-hydroxyacrylic acid. The molecular weight of i~ the suitable compounds of this class is generally above 20,000.
Other suitable stabilizers are the phosphonic acids, particularly the polyphosphonic acids, such as l-hydroxyethane-l, l-diphosphonic acid, dime-thylaminomethane diphosphonic acid, phosphonobutane-tricarboxylic acid, methane-tri-methylenephos-phonic acid.
The stabilization of the suspensions can also be achieved by adding to the suspension, stabilizers which have no acid character, such as anionic surface-active compounds, as water-soluble salts. In this case the reduc-tion of the pll value to values below 12.5 or particularly 11.5 must naturally ~ 18 -irc~

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be effected by the above-described measures. For example, the pH value can be reduced by washing and/or by adding acid.
But the further stabilization ofthe suspensions car~ also be effected with non-ionic surface~active compounds or tensides, where the water-insoluble non-ionic tensides, that is, compounds with turbidity points in water below about 50C, particularly below room temperature, are particularly suitable. These compounds have in common that they have a tur-bidity point in aqueous butyldiglycol solution in the range of about 40C to 85C, particularly 55C to 85C, determined according to DIN 53917.
Among the non-ionic surface-active compounds which are suitable as suspension stabilizers according to the invention are the ethoxylation products of alkanols with 16 to 18 carbon atoms with 1 to 8 mols of ethylene oxide per mol of alcohol.
Other suitable non-ionic stabilizers are found in the .
group of compounds which have as a hydrophobic radical a long-chained alkyl or alkenyl radical containing mostly 10 to 20, r preferably 12 to 18 carbon atoms, which is mostly straight-chained but which can also be branched. Unsaturated, hydro-phobic radicals are mostly mono-unsaturated, like the frequently encountered oleyl radical. The hydrophilic group is mostly formed by polyoxyalkylene glycols, like ethylene glycol, propy-lene glycol, polyoxyethy'ene glycol or glycerin radicals which are connected with the hydrophobic radical over ester, amide, ether or amino groups. Particularly interesting are the ethylene oxide adducts. Among the ethylene oxide adducts with the same turbidity point, those with the longer hydrophobic radical of C14 to C18 are generally preferred. Suitable stabilizers, in addition to the ethylene oxide adduc-ts onto fatty alcohols, are the mono- and diethanolamides of carboxylic acids, preferably fatty acids, w:ith 10 to 20, preferably 12 to 18, and particularly 12 to 14 carbon atoms. These compounds are ~ jrc:l~

derived primarily from saturated and straight-chalned carboxylic acids. The best suitable amides can be considered as reaction products of carboxylic acid amides withethylene oxide; here, the number of ethylene oxide units is mostly 1 to 6, and part~
icularly 1 to 4.
Ester-like suspension stabilizers which can be employed are the products which can be consi~ered as addition products of ethylene oxide onto the carboxylic acids, for example, the addition products of 1 to 10 mols of ethylene oxide per mol of carboxylic acid. In such esters, polyalco-~hols with more than two hydroxyl groups, such as glycerin, can also be used as the alcohol component.
Instead of the above-mentioned ethoxylation products, the corresponding ethoxylation products of fatty amines, hence particularly ethoxylation products of preferably saturated primary alkyl amines having 16 to 18 carbon atoms with 1 to 8 mols of ethylene oxide per mol of amine can also be used.
Suitable here, too, are the non-ethoxylated amines. But products with 2 to 5 mols of ethylene oxide per mol of amine are also 20 highly suitable. Also mentioned here as stabilizing adducts are the ethoxylated alkylphenols with a turbidity point in water of below room temperature or a turbidity point in aqueous .- butyldiglycol solution of below 85 C (DIN 53917). These pro-.-~ ducts have about 5 to 8 mols of ethylene oxide per mol of alkyl-:~ phenol, adducts with 6 to 7 mols of ethylene oxide being prefer-red.
The specific compounds which illustrate the .~ above-mentioned classes of non-ionic stabilizing agents are lauric acid monoethanolamide, coconut fatty acid mono-ethanolamide, myristic acid monoethanolamide, palmitic acid monoethanolamide, stearic acid monoethanolamide, and oleic acid monoethanolamide; lauric/myristic acid diethanolamide, the diethanolamide of a fatty acid mix-ture of lauric acid and - 20 ~
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~3~3~4 myristic acid, and oleic acid diethanolamide; an ethoxylation product of 5 mols of ethylene oxide per mol of a saturated alcohol oramine derived from tallow taffy acid, where the non-ethoxylated saturated tallow fatty amine can likewise be used; the adduct of 7 mols of ethylene oxide onto nonylphenol.
The polymeric, preferably' synthetic, polyhydroxy compounds, such as polyvinyl alcohol, can be used as compounds suitable as stabilizers, which have neither an acid nor a surface-active character.
lU If stabilizing additives are used according to the invention, particularly the above-mentioned anionic or non-ionic surface-actlve compounds, their portion in the suspensions according to the invention can be extremely low, and the desired stabilizing effect can still be obtained. This, too, is a particular advantage of the invention. For example, sus-pensions prepared according to the invention and subsequently stabilized preferably have an aluminosilicate content of be-tween 30% and 55% by weight, and a content of anionic and/or non-ionic surface-active compounds in the range of 0.1% to 1%
by weight. The concentrations can naturally differ from the indicated concentrations in one or other direction, but the indicated range is clearly preferred, particularly the range of 0.2~ to 0.7% by weight.
The suspensions prepared according to the invention are highly suitable for various applications. Due to the special type of preparation, particularly the combination of certain mixing ratios with the above-described unusually rapid precipitation and practically immediate processing, the sus-pensions already have stabilities and rheological properties which are much better than the properties of aluminosilicate suspensions prepared in conventional manner. These suspensions can, therefore, already be used as such, when stabilized as described above, for example by the addition of an anionic - 21 ~
jrc~

or non-ionic surface-active compounds, as liquid scouring agents, with improve~ suspension stability. When used as liquid scouring agents, additional tensides or other conven-tional ingredients of such agents, for example, builder salts from the group of the inorganic and organic sequest~ants for the hardness formers of water, can optionally be added.
Another use of the suspensions according to the invention, which is particularly important in practice, is their processing to powdered, dry-appearing products. Accord-ing to the invention, the suspension is subjected to atomiza-tion where the suspension is atomized through nozzles or is applied on rotating disks and is thus finely divided, and the fine droplets formed by the atomization are air dried in a hot air current. The products thus obtained are characterized by a particularly favorable re-suspension behavior. Further-more, the powdered products obtained according to the inven-tion are excellently suitable for use in washing and cleaning agent compositions. In the above-described applications, the suspensions are preferably used in stabilized form.
A particularly important application of the sus-pensions according to the invention is the processing of the same to powdered washing andcleaning agents.
; The following examples are illustrative of the practice of the invention without being limitative in any manner:
EXAMPLES
The calcium-binding power of the aluminosilicates produced in the following examples was determined as follows:
1 liter of an aqueous solution containing 0.59~ gm of CaC12 (=300 mg CaO/l = 30 deg. dH-German hardness) and standardized with dilute NaOH to pH value of 10, was mixed with 1 gm of aluminosilicate (related to AS-active substance). The suspension was then stirred vigorously for jrc:,'i ~ "

2~
15 minutes at a temperature of 22 C (-~ 2 C). After filtering off the aluminosilicate, the residual hardness x of the fil-trate is de-termined, from which the calcium binding power is calculated in mg CaO/gm AS according to the formula:
(30 - x) . 10. For determining the residual hardness, the calcium content is determined by titration with EDTA (see below).
The abbreviations used below have the following meaning:
TA + 5 EO - an addition product of 5 mols of ethylene oxide per mol of a substantially saturated fatty alcohol produced by the reduction of tallow fatty acid.
ABS ~ the salt of an alkylbenzene sulfonic acid with about 11 to 13 carbon atoms in the alkyl chain, obtained by condensation of straight-chained olefins with benzene and sulfonation of the alkylbenzene thus obtained.
OA ~ 10 EO - an addition product of ethylene oxide onto technical oleyl alcohol in a molar ratio of 10:1.

Waterglass - a sodium silicate (Na O : SiO calculated ratio = 1.3.35).
CMC - the salt of carboxymethyl cellulose.
EDTA - the salt of ethylenediaminetetraacetic acid.
Perborate - a technical product of the approximate composition NaBO2 H2O2- 3 H2 Soap - the sodium salt of a hardened tallow fatty acid.

l-A~
A precipitating vessel with a capacity of 60 1 was employed. This vessel was charged with 32 kg of an aluminate solution preheated to 60 C which had the following calculated composition (molar ratio):
Na20 : 2.68; A1203 : 1.0; ~120 : 35.55.

jrc P~-From a storage vessel were then added within 6 to 8 seconds under vigorous stirring with a propeller stirrer (670 rpm), 10.0 kg of sodium silicate solution, which was likewise preheated to 60C. The sodium silicate solution has a solid content of 35% by weight.
~ ltogether the sodium silicate solution corres-ponded to the following composition (molar ratio):
Na20 : 0.52; SiO2 : 1.80; H20 : 14.45.
The molar ratio refers to the total calculated amount of A1203 contained in the sodium aluminate solution, which was assumed arbitrarily to be 1Ø The sum of the individual data for Na20, A1203, SiO2 and H20 yields thus the molar ratios that are present in the reaction mixture after complete combination of the reactants, here:
Na20 : 3.2; A1203 : 1.0; SiO2 : 1.8; H20 : 50.
Immediately after the addition of the sodium silicate solution was completed, the viscosity of the aqueous system had already passed beyond the viscosity maximum and was decreasing again. The aqueous system, which was still a highly viscous gel was, in this stage, immediately trans-ferred through a valve in the bottom of the reaction vessel, which is now open to a homogenizer (comminution device) of the stator-rotor type. The comminution device is a Supraton ~ , manufacturer: Auer & Zucker, Federal Republic of Germany.
The amount recycled was 1000 to 1500 l/h.
During the treatment in the cominution aevice, the viscosity decreased to attain a limiting value which was clearly above the viscosity of the aluminate or silicate solution employed as starting materials.
While the suspension was being recycled through the comminution device, the balance of about 4.1 kg of the sodium silicate solution of the above-indicated composition _24 _ jrc:l^J

and temperature was added to the preclpitating vessel within 10 to 12 seconds. Altogether 20 seconds were re~uired for the complete combination of the reactants. The end tempera-ture in the reaction mixture was 70 - 72C.
~ fter a circulation for 5 minutes from the pre-cipitatiny vessel to the comminution device to the precipi-tatiny vessel, the suspension obtained, which could be pro-cessed in this stage to give finished washing and cleaning agents, was placed on a filter, and the mother liquor was partly removed, about 40% of the total water. The filter residue was treated on the filter with fresh water unti] the filtrate water reached a pH of 10. The product obtained, on the solids content,corresponded to the formula 1.1 Na20 .
1.0 A1203 . 1.8 SiO2.
l-B) ~lternately, the above suspension obtained, after comminution, was transferred to a crystallization vessel with a capacity of about 150 1 (a smaller vessel could also be used) for the production of a crystalline product. The temperature in the crystallization vessel was immediately raised to about 90C by steam injection, which takes about 5 minutes. After this temperature was attained the suspension was left standing without stir-ring for about 30 minutes at this temperature and sub-sequently was placed on a filter. A consi~erable portion of the mother liquor with about 1/3 of the total alkali was removed. The amount of drained water was replaced twice with a corresponding amount of wash water, after which a residue on the filter of the composition lu12 Na20 .
1.0 A1203 .1.8 SiO2 . 23 H20 was obtained. This product was stirred into some water, and the dilute suspension obtained could be fed through pumps directly to the plant for the production of the detergent compositions.

jrc ~ i t 3 :L2~

The product produced as described above has a calcium-binding power of I63 mg CaO/gm AS. The p~rticle si.ze distribution was 85% < 5~; 94~ < lO~; 99% < 20~.
The aluminosilicate of the above-described suspension shows the following interference lines in the X-ray diffraction diagram:
12.4; 8.6; 7.0; 4.1 (~); 3.68 (+~; 3.38 (+);
3.26 ~+); 2.96 (+); 2.73 (+); 2.60 (~).
: lO If the.aluminosilicate is less crystallized, the intensity of these X-ray diffraction lines decreased.
The strongest interference lines are identified by a ~(+)~ All d-values were recorded with CuK radiation, and are given in Angstroms (A).
,, 1 C) From the residue on the filter produced as ~ described in l-B and containing crystalline sodium alumino-,~, .
silicate, stabilized sodium aluminosilicate suspensions of : the following compositions were obtained by mixing with tenside-containing water:
` a) sodium aluminosilicate, 33% by weight; alkyl-- benzene sulfonic acid (sodium-salt,Cll-Cl3 alkyl), 0.5% by weight;
b) sodium aluminosilicate, 38% by weight; ethoxyla-tion product of 5 mols of ethylene oxide onto l mol of a C 8 fatty alcohol, 0.5% by weight;
c) sodium aluminosilicate, 40% by weight; ethoxyla-tion product of b), 0.25% by weight;
d) sodium aluminosilicate, 35% by weight; poly-N-hydroxyacrylic.acid (molecul.ar weight about lOO,OOO), 0.5% by weight;
e) sodium aluminosilicate, 38% by weight; l-hydroxy-ethane-l,]-diphosphonic acid, 0.8% by weight.

jrc:~ !, ., ::

In the case of the variants d) and e), the addition of the dispersing agent in acidic form contributes to the partial neutralization of the suspension.

A suspension of crystallized sodium alumino-silicate was prepared as described in Example l-B, but with the difference that the sodium aluminosilicate was only washed out until the suspension had a NaOH content of 1.15% ~`
and a solid content of 36%. The pH value of this suspension was still above 13. 20% aqueous sulfuric acid was dosed in , this suspension with stirrinq in a vessel with a capacity of 150 1 until the pH value dropped to a range of 10.3 to 10.8.
The suspension thus obtained had a sodium aluminosilicate content of 32% by weiqht, a content of sodium sul~ate of 2.~%
by weight, and a pH value of 10.3. The calcium-binding power of the sodium aluminosilicate was 157 ma CaO/gm AS. A micro-scopic examination of the sodium aluminosilicates showed complete absence of undesired agglomeration of the primar~
particles of lar~er units.

~ Suspensions of partly to completely crystal-;~ lized sodium aluminosilicates were prepared as described in Example l-B, with the variations indicated below. The sodium aluminosilicates are also characterized by their calcium-binding power indicated in the tables below:
Formula: 2.8 Na20 . 1.0 A1203 . 1.8 SiG2 . 50 H20 Na20A123 SiO2 H20 Sodium silicate solution 0.52 1.80 14.45 Sodium aluminate solution 2.28 1.0 35.55 3rc: 1.1..,~.

~3~24 Precipitation at 60C, recycled for 5 minutes with Supraton ~ , heated within 5 minutes to crystallization tem-perature (80C and 90 C respectively) and crystallized for another 60 minutes under stirring. Final and intermedi.ate samples were examined, and the suspensions were washed out after crystallization as indicated to a pH value between 9 and 11.5.
TABLE I
.~ Crystallization temperature 80C
Crystallization time ~min.) Calcium binding power(mg CaO/gm AS) :5 . 37 Crystallization temperature 90C

, : Crystallization time (min.) Calcium binding power(mg CaO/gm AS) ~'15 145 The procedure was as in Example 3, but with the following differences:

Formula: 2.8 Na20 . 1.0 A1203 . 1.8 SiO2 . 60 H20 Na2~ A123 Si2 H2 ' Sodi.um silicate solution 0.52 1.80 14.45 Sodium aluminatè 2.28 1.0 45.55 Precipitation at 60 C, recycled for 5 minutes with Supraton ~ , heated within 5 minutes to 85 crystallization temperature, and c.rystallized for another 90 minutes under stirring. Final and intermediate samples were examined.

~rc:

3~L2~

T BLR II

. .
Crystallization time (min.) Calcium binding power(mg CaO/gm AS) _XAMPLE 5 The procedure was as in Example 3, but with the following differences: -Formula: 3.2 Na20 . 1.0 A1203 . 1.8 SiO2 . 44 H20 ' 10 Na20 A123 Si2 H2 Sodium silicate solution 0.52 1.80 14.45 Sodium aluminate 2.68 1.0 29.55 _ . . _ _ . ... . . . . . _ _ Precipitation at 60 C, recycled for 5 minutes with Supraton ~ , heated within 5 minutes to 90 C crystallization temperature, and crystallized for another 60 minutes without ~- stirring. Final and intermediate samples were examined.
_ABLE III

C'rystallization time (min.) Calcium binding power(mg CaO/gm AS) - _ ;

The procedure was as in Example 3, but with the following differences:
Formula: 3.2 Na20 . 1.0 A1203 . 1.8 SiO2 . 60 H20 1 rc:
.

z~

_2 A123 SiO2 H20 Sodium silicate solution 0.52 1.80 14.45 Sodium aluminate 2.68 1.0 45.55 Precipitation at 60C, recycled for 5 minutes with Supraton (~) , heated within 5 minutes to crystallization temperature (80C and 90C respectively), and crystallized " for 60 and 90 minutes respectively under stirring. End-and intermediate samples were examined.
_ABLE IV

Crystallization temperature 80C
Crystallization time Calcium-binding power Particle size (min.) (mg CaO/gmAS) distribution (portions in %) <10 lJ <20 ~
. .

Crystallization temperature 90C
Crystallization time Calcium-binding power Particle size - (min.) (mg CaO/amAS) disbribution (portions in ~6) <10 ~ <20 1 163 99 > 99 The procedure was as in Example 3, but with the ~ollowing differences:
Formula: 3-6 Na2 1.0 A1203. 1-8 Si2 ~ 50 ~2 Na20A123 SiO2 H20 Sodium silicate solution 0.52 1.80 1~.45 Sodium aluminate 3.08 1.0 35.55 jrc:

Precipitation at 60C, recycled for 5 minutes with '~
Supraton O , heated within 5 minutes to crystallization temper-ature (70 C) and crystallized for another 45 minutes under stir-ring. Final and intermediate samples were examined.
TABLE

C stallization temperature 70C

Crystallization time Calcium-binding power Particle size (min.) (mg CaO/gmAS) distribution (portion in %) <10 ~ <20 ~
~ _ _ _ .
; 15 165 87 97 The procedure was as in Example 3, but with the following differences:

Formula: 3.6 Na20 . . 2 3 2 2 Na20 A123 Si.02 H2 Sodium silicate solution 0.52 1.80 14.45 Sodium aluminate 3.08 1.0 55.55 Precipitation at 60 C, recycled for 5 minutes with Supraton ~ , heated within 5 minutes to crystallization temper-ature of 90 C and crystallized for another 90 minutes under stir-ring. Final and intermediate samples were examined.
_BLE VI

Crystallization time Calcium bindinq Particle size distri-(min) power (mg CaO/gm bution (portion in ~) _ AS) <5 ~ <10 ~ ~20 165 45 99 > 99 _ ~ 31 -1~3~

_XAMPLE 9 The procedure was as in Example 3, but with the following differences:
Formula: 3.2 Na20 . 1.0 A1203 . 1.8 SiO2 . 70 H20 Na20 ~l23 SiO2 H2 Sodium silicate solution 0.52 1.80 1~.45 . Sodium aluminate 2.68 1.0 55.55 ~ Precipitation temperature varied between 10 and 90C.
; Crystallization temperature at 90 - 95C.
TABLE VII
Precipitation temp. Crystallization time Calcium binding . C (hours)power ~mg CaO/gm AS) 1.5 148 1.0 158 1.0 161 2.0 170 2.0 158 1.0 157 2.0 162 2.0 159 1.0 163 - 2.0 169 -Powdered, tricklable detergents of the composition indicated in Table VIII were produced as follows: A stock suspension was prepared by introducing the filter residue produced according to Example l-B and partially neutralized to a pl~ value of 10.5, into a dispersion of a hydrogenated tallow fatty alcohol ethoxylated with 5 mols of ethylcne oxide per mol of alcohol. This stock suspension contained 40~ by weight jrc:

1~3~
aluminosilicate and 0.5% by weight of the dispersing ayent, based on the total weight of the suspension. This stock suspension was pumped from a storage tank into a vessel into which l:he other components and so much water were added suc-cessively under stirring that a deteryent mixture (slurry) containing ahout 45~ by weight o~ water was formed. This slurry was passed by pumping to the atomizing nozzles arranged at the upper end of a spray drying tower and transferred into a fine powder by atomization and passing through hot air in counter flow (about 260C).
Compos _ on A Co osition s ABS 1.4% TA + 10 EO 7.0%
OA + 10 EO 8.0% TA + 5 EO (2) 2.7%
Sodium tripolyphosphate 7.8% Sodium tripolyphosphate 20.0%
Waterglass 5.4% Sodium carbonate 5.0%

CMC 0.8% Waterglass 3.0%
CMC 1.8%
Aluminosilicate(l)(AS) 36.0% Aluminosilicate(l)(AS) 18.0%
TA + 5 EO (l) 0.45% TA + 5 EO (l) 0.23%
Balance water and Na2S04 EDTA 0.5%
MgSiO3 2.5%
Perborate (3) 28.0%
Soap 2.5%
Balance water and Na2S04 (l) introduced with stock suspension (2~ TA + 5 E0 added with the other components (3) added after spray drying the remainder of the slurry.
Instead of the suspension being stabilized with TA
+ 5 EO, it is also possible to use in the production of a detergent corresponding to 10 B an aluminosilicate suspension which contains a polyacrylic acid, for example, as a stabiliz-ing agent. Since polyacrylic acid or the neutralized salt there-of is a sequestrant for calcium, the sodium tripolyphosphate rc: .

~X~ 3~
portion can be reduced correspondingly. In the production of detergents containing ABS, the ABS containing a]umino-silicate suspension according to the invention can be used, specifically an ABS with 11 to 13 carbon atoms in the alkyl radical.

An aqueous suspension prepared according to Example l, which contained about 40% by weight of aluminosilicate, was atomized in a hot air current and thus dried, that is, lib-erated of adhering water. The powdered aluminosilicate obtained is excellently suitable as a water softener and as a builder salt for detergents. The procedure described above is also used with advantage with a suspension containing 40%
by weight of aluminosilicate, as described in Example l-C
a) or which corresponds to Example 1-C c). In these cases a product is obtained which is both low-dusting and which is also excellently suitable as water softeners and as builder salts for detergents.
The preceding specific embodiments are illustrative of the practice of the invention. It is to be understood, ; however, that other expedients known to those skilled in the art or disclosed herein, may be employed without departing from the spirit of the invention or the scope of the appended claims.

- ~4 -jrc:

Claims (31)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for the preparation of finely-divided water-soluble calcium-binding aluminosilicate suspensions suitable for detergent formulations comprising 1) mixing an aqueous alkali metal aluminate solution with an aqueous alkali metal silicate solution in the presence of an excess of alkali to give a silicate compound having a calcium-binding power, when measured at 22°C of at least 50 mg CaO/gm of anhydrous active substance and having the formula, combined water not shown:

(M2O)0.8-1.3 ? Al2O3 ? (SiO2)1.75-2.0 wherein M represents an alkali metal, wherein said aqueous solutions have a composition corresponding to the desired Al2O3 and SiO3 amounts of the above formula, with at least 2.5 mols M2O/mols Al2O3 and not more than 80 mols H2O/mol Al2O3, rapidly with vigorous agitation, wherein the total amount of said reactants are mixed with each other within a period of about 4 to 60 seconds, 2) then, within about 0 to 120 seconds after the calcu-lated amounts of reactants required for formation of half the anticipated amount of the product have been mixed, homogenizing said mixture by recycling the same through a separate area where the entire amount of said mixture is subjected to a cavitation effect at least once for a period not later than 60 seconds after said mixing step is completed, 3) maintaining the homogenized aqueous suspension at an elevated temperature until formation of at least some aluminosilicate crystals, said aluminosilicate crystals having a particle size between 0.1 and 10 µ.
4) adjusting the aluminosilicate suspension to a pH of below 12.5, and 5) recovering said aluminosilicate suspension.

2. The method of claim 1 wherein the ratio of A12O3 to SiO2 is from 1:1.8 to 1:1.9.

3. The method of claim 1 wherein the alkali metal cation M
is selected from the group consisting of lithium, sodium and potassium.

4. The method of claim 3 wherein the alkali metal cation M
is sodium.

5. The method of claim 1 wherein said mixing step 1 is con-ducted at a temperature of from 55°C to 100°C utilizing preheated solutions.

6. The method of claim 1 wherein said mixing step 1 is con-ducted at a temperature of from 60°C to 85°C utilizing preheated solutions.

7. The method of claim 1 wherein the ratio of M2O to SiO2 in said alkali metal silicate solution is from 1:2 to 1:4.

8. The method of claim 1 wherein the ratio of M2O to SiO2 in said alkali metal silicate solution is from 1:2.2 to 1:3.8.

9. The method of claim 1 wherein said elevated temperature of step 3 is from 50°C to 100°C and is maintained until the desired degree of crystallization is reached.

10. The method of claim 1 wherein said elevated temperature of step 3 is from 70°C to 95°C and is maintained until the desired degree of crystallization is reached.

11. The method of claim 1 wherein said elevated temperature of step 3 is above 50°C and at least 5° higher than the temperature of said mixing step 1.

12. The method of claim 1 wherein said mixing step 1 is conducted at a temperature of from 60°C to 85°C and said elevated temperature of step 3 is from 90°C to 95°C.

13. The method of claim 1, step 4, wherein the crystallizing suspension which is thioxtropic at this stage is agitated to a point where the suspension is just sufficiently fluid to be pumpable.

14. The method of claim 8 wherein said mixing step 1 is conducted at a temperature of from 60°C to 85°C and said elevated temperature of step 3 is from 90°C to 95°C.

15. The method of claim 8 wherein said mixing step 1 is conducted at a temperature of from 60°C to 85°C and said elevated temperature of step 3 is first adjusted to from 90°C
to 95°C by steam injection and thereafter allowed to drop to a range of from 50°C and 85°C.

16. The method of claim 1 wherein the ratio of M?O
to Al2O3 is from 2.5:1 to 4:1.

17. The method of claim 1 wherein the ratio of M20 to Al2O3 is from 2.8:1 to 3.8:1.

18. The method of claim 1 wherein the ratio of M2O to Al2O3 is from 3.0:1 to 3.6:1.

19. The method of claim 1 wherein the ratio of H2O to Al203 is from 40:1 to 80:1.

20. The method of claim 1 wherein the ratio of H2O to A12O3 is from 45:1 to 75:1.

21. The method of claim 1 wherein the ratio of H2O to A12O3 is from 45:1 to 60:1.

22. The method of claim 1 wherein the calcium binding power of said aluminosilicates is from 50 to 200 mg CaO/gm AS, when measured at 22°C.

23. The method of claim 1 wherein the calcium binding power of said aluminosilicates is from 100 to 200 mg CaO/gm AS, when measured at 22°C.

24. The method of claim 1 wherein said step 3 of homogenizing by recycling is conducted for 2 to 7 recycles.

25. The method of claim 1 wherein said step 2 is commenced from 1 to 120 seconds after said maximum viscosity of the aqueous mixture has been attained.

26. The method of claim 1 wherein said pH of below 12.5 is attained at least partially by neutralization with a mineral acid.

27. The method of claim 1 wherein said pH of below 12.5 is attained at least partially by neutralization with an anionic surface-active compound of the sulfate or sulfonate type in the acid form.

28. The method of claim 1 wherein said pH of below 12.5 is attained at least partially by neutralization with a polymeric polycarboxylic acid having a molecular weight above 20,000.

29. The method of claim 1 wherein said pH of below 12.5 is attained at least partially by neutralization with a polyphosphonic acid.

30. The method of claim 1 wherein said aluminosilicate suspensions are recovered in step 6 with a content of from 30% to 55% by weight of said aluminosilicate and from 0.1% to 1% by weight of an organic suspension stabilizer.

31. The process of claim 30 wherein said organic suspen-sion stabilizer is selected from the group consisting of water-soluble salts of anionic surface-active compounds of the sulfate or sulfonate type, polymeric polyhydroxy compounds and non-ionic surface-active compounds having a turbidity point according to DIN 53917 in aqueous butyl diglycol solution of between 40°C and 85°C.