GB1576843A

GB1576843A - Process for the preparation of an aqueous suspension of finely-divided water-insoluble silicates capable of cation exchange

Info

Publication number: GB1576843A
Application number: GB458277A
Authority: GB
Original assignee: Henkel AG and Co KGaA; Degussa GmbH; Deutsche Gold und Silber Scheideanstalt
Current assignee: Henkel AG and Co KGaA; Evonik Operations GmbH
Priority date: 1976-02-06
Filing date: 1977-02-04
Publication date: 1980-10-15
Also published as: JPS5295600A; NL7700443A; AT356628B; BR7700719A; CH630044A5; DE2704310C2; ATA84276A; ES455646A1; BE851091A; DE2704310A1; FR2340128B1; SE7700492L; IT1082460B; SE426810B; FR2340128A1; JPS6137320B2; CA1103124A

Abstract

An aqueous suspension, suitable for further processing in detergents and cleaning agents, of a water-insoluble silicate of the general formula I: (Cat2O)0.8-1.3.(Al2O3).(SiO2)1.75-2.0 (I> in which Cat is an alkali metal cation, is obtained by mixing alkali metal aluminate dissolved in water with alkali metal silicate dissolved in water in the presence of excess alkali. In order to meet the requirement for a process which, in a particularly short reaction time and with a high space-time yield, produces aluminium silicates of the abovementioned formula, which are extremely finely particulate but at the same time have a narrow particle size spectrum, the aqueous solutions, whose arithmetic overall composition in terms of their Al2O3 and their SiO2 content corresponds to the abovementioned formula, but which in total have at least 2.5 mol of Cat2O per mole of Al2O3 and at most 80 mol of water per mole of Al2O3 of the formula, are mixed rapidly and with vigorous stirring and the suspension obtained - before the solutions have been combined completely, if appropriate - is passed at least once - and at least for as long as the solutions have not been completely mixed - through a size reduction appliance.

Description

(54) PROCESS FOR THE PREPARATION OF AN AQUEOUS SUSPENSION OF FINELY-DIVIDED WATER-INSOLUBLE SILICATES CAPABLE OF CATION EXCHANGE (71) We, HENKEL KOMMANDITGESELLSCHAFT AUF AKTIEN and DEUTSCHE GOLD- UND SILBER-SCHEIDEANSTALT VORMALS ROESSLER, both German Companies, of 67 Henkelstrasse, 4000 Duesseldorf Holthausen, Federal Republic of Germany, and Weissfrauenstrasse, 9, 6000 Frankfurt (Main), Federal Republic of Germany, respectively, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a process for the preparation of aqueous suspensions of finely divided water-insoluble silicates of the general formula (Kat2O)08~, 3. (A12O3) . (SiO2)1.7520 (I) capable of cation exchange and still containing bound water, and suitable for the further processing to washing and cleaning agents. In this formula Kat represents an alkali metal cation. The invention further relates to the suspensions obtainable according to the process and their use especially for the preparation of washing and cleaning agents.

The compounds of the general formula I are capable of cation exchange with substances forming hardness of water, thus magnesium and calcium ions. Their calcium binding power generally lies above 50 mg CaO/g active substance (AS), preferably in the range from 100 to 200 mg of CaO/g of active substance. The calcium binding power can be found by the process indicated in the part containing the Examples; by "active substance" is meant the solid obtained by drying for one hour at 8000 C.

The water-insoluble silicates described above are of special interest as components of washing and cleaning agents, since they are capable of replacing wholly or partly the phosphate building substances still largely used at the present time.

Aluminium silicates of the formula given above capable of cation exchange are known. Their synthesis takes place generally be preparing an aqueous synthesis mixture which consists analytically of Awl203 and SiO2 in a given proportion and also Kat2O and water, by uniting solutions of individual components. Solutions of alkali metal aluminate and alkali metal silicate mostly serve as the starting substances.

A plurality of different processes for the preparation of such compounds is already available within the framework outlined above. However, a process is needed which provides aluminium silicates of the above given formula with a specially short reaction time and high space-time-yield, which are extremely finely divided, but in this case have a narrow spectrum of grain sizes.

The invention relates to a process for the preparation of an aqueous suspension of a finely divided water-insoluble silicate capable of cation exchange and still containing bound water, of the general formula: (Kat20)0,8 ,,3 . (Al2o3) . (sio2)r 7s-2 o (1) in which Kat represents an alkali metal cation which comprises mixing an aqueous solution of an alkali metal aluminate or the reactants which will produce an alkali metal aluminate in situ and an aqueous solution of an alkali metal silicate or the reactants which will produce an alkali metal silicate in situ, in which the calculated total composition of the aqueous solutions with respect to their Awl203 and their SiO2 content corresponds to formula 1 above, but that the aqueous solutions in total contain not more than 80 mol of water per mol of Awl203 of the formula and contain an excess of alkali such that in total at least 2.5 mol of Kat2O is present per mol of Awl203, and in which at least part of the aqueous solutions to be mixed are mixed rapidly with vigorous stirring and the suspension obtained further vigorously stirred, and in which when the viscosity of the suspension so obtained has reached a maximum value and begun to fall again, the suspension is passed through a comminuting apparatus, and thereafter adding rapidly and with vigorous stirring to the suspension a measured quantity or repeated measured quantities of any unmixed aqueous solutions, followed after each such addition by further vigorous stirring and at the aforesaid viscosity level passing the solution through a comminuting apparatus, until all the aqueous solutions to be mixed have been mixed.

The further vigorous stirring may on each occurrence be continued until the viscosity level of the suspension has reached a maximumvalue and begun to fall again but may be discontinued before a minimum viscosity level is reached. After all the aqueous solutions to be mixed have been mixed and the suspension passed through the comminuting apparatus, the suspension may be maintained at an elevated temperature until at least partial crystallization has taken place.

Preferably the suspension is then adjusted to a pH value below 12.5, by washing out excess alkali, removal of at least a part of the adhering mother liquor and at least partly replacing by water, and/or by addition of an acid.

Preferred alkali metal cations are the potassium and especially the sodium ion.

In the following pages the invention is illustrated by means of the sodium aluminium silicates, but the details obviously also apply to the aluminium silicates of other cations.

The composition of the aluminium silicates contained in the suspensions prepared according to the invention can be found by the usual elementary analysis, wherein the aluminium silicates are isolated from the suspension after washing out to a pH value of 10 (in a suspension containing for example, 30V by weight of dry substance) and are dried until the adhering water is removed. The above indicated formula comprises both amorphous compounds, and more or less completely crystallised compounds of the same empirical composition. The degree of crystallisation can also be determined on the aluminium silicate isolated as previously described by comparison of the X-ray diffraction diagram with completely crystallised samples (maximum intensity of the X-ray diffraction lines).

The sequence of the mixing is optional. According to a preferred variant of the invention the mixing of the reaction solutions, for example, sodium aluminate and sodium silicate is carried out so that some liquid is placed in the reaction vessel, especially water or at least a part of the sodium aluminate solution, and the remaining reactants are quickly introduced while stirring. In such case it is advantageous to work so that in the reaction vessel a calculated excess of Awl203 exists until the solutions of the reactants are united. For example, the aluminate solution is inserted and the sodium silicate solution is introduced quickly with stirring. The reverse sequence is also possible, however, in which, for example, an at first highly concentrated sodium silicate solution is first of all diluted with some water.

On the other hand it is also possible to introduce only a part of the aluminate solution, thus for example, 10 /n or more, and the rest of the aluminate solution is measured into the reaction system during the reaction of the solutions with one another. All percentage data are in weights percent, provided nothing else is indicated.

Basically the reaction can be carried out at any temperature, while the range of temperature in which water is liquid at normal pressure is obviously preferred.

The temperatures mostly lie above room temperature.

The reaction can be accelerated by increasing the temperature, and it is preferred to carry out the mixing of the solutions at a temperature between 55" and 100"C, preferably between 60 and 85"C. In such case the aluminate solution and/or silicate solution are preferably used preheated to a temperature in the given range.

The sodium aluminate is introduced into the reaction system as a solution of sodium aluminate. the proportion of Na2O:AI203 in the sodium aluminate solution need not necessarily correspond to the formula NaAIO2, however, on the contrary, other proportions of Na2O:AI203 may be used as long as it is ensured that the synthesis mixture prepared by mixing the aluminate solution with the silicate solution has a composition in the given range. The proportion Na2O/A12O3 may thus be greater or less than 1 in the sodium aluminate solution, while as a limiting case, the aluminate may also be used in the form of reactive aluminium hydrate, which namely is converted in situ in sodium aluminate during the mixing by the alkali then correspondingly enriched in the silicate solution.

In general, the proportion of alkali metal oxide to Al203 in the aluminate solution lies above 1.5, for example in the range between 2.0 and 3.5. The range is usually preferred between 2.0 and 3.2.

Corresponding to the composition of the aluminate solution variable within wide limits, the composition of the silicate solution may also be varied within wide limits. The silicate is generally used as water-soluble silicate, for example waterglass. If the presence of the excess alkali necessary according to the invention is ensured by an enrichment of alkali in the sodium aluminate solution, an alkalipoor silicate may also be used, when as limiting case the silicic acid capable of reaction is to be mentioned, which under the reaction conditions is converted into an alkali metal silicate in situ in the synthesis mixture. Most advantageous, however, is the use of an alkali metal silicate with a molar ratio Kat2O:SiO2 of about 1:2.0 to 1:4, especially 1:2.2 to 1:3.8.

The composition of the synthesis mixture used within the framework of the invention corresponds with regard to the proportion of SiO2:A12O3 analytically to the proportion in the suspended aluminium silicates indicated above, which amounts to 1.75:1 to 2:1. The preferred aluminium silicates especially the preferred sodium aluminium silicates, have frequently proportions of SiO2:Al2O3 in the range from 1.8 to 1.9. The composition of the suspended aluminium silicate corresponds with respect to the SiO2/AI203 proportion of the composition of the synthesis mixture, while insignificant deviations may be caused in that besides the precipitated aluminium silicate, a small amount of unreacted aluminate or silicate is still present, which is then substantially removed on washing out. Such deviations, however, are trivial and lie in their magnitude mostly in the range of the limits of error of the analytical determinations.

A specially important parameter is the amount of alkali present in the synthesis mixture; it amounts to at least 2.5 mol of alkali metal oxide per mol of Awl203. A ratio of 2.8 to 3.8, especially from 3.0 to 3.6 mol of alkali metal oxide per mol of Al203 is preferred in such case. The calculated Na2O content or alkali metal oxide content in the isolated aluminium silicate lies in the given framework, and mostly at about 0.8 to 1.2, especially at 0.9 to 1.15 mol of Na2O per mol of Awl203.

Molecular proportions above 4 mol of alkali metal oxide per mol of Al203 are generally no more advantageous within the meaning of the invention.

A further essential parameter is the amount of water present.

The water content of the synthesis mixture should be not more than 80 mol of H2O per mol of Awl203. The lower limits of the water content is given by the limits of the stirrability; i.e. at least so much water must be added to the synthesis mixture that the mixture can be stirred in all stages of the process. The lower limits of water in the synthesis mixture may lie under 45 mol of water per mol of aluminium oxide.

Generally, however, amounts of water in the range from 45 to 75 mol of water/mol of Awl203 have proved satisfactory. This range is then specially advantageous, for it is of importance to prepare products which have the highest possible ion exchange capacity in the given composition, for example the highest possible binding capacity for the hardness-forming ions of the usual water. Such products are preferably highly crystalline and have the structure of the so-called zeolite A. Depending on the time of the crystallisation step, other crystalline and/or amorphous compounds-for example hydro-sodalite may also be present besides the zeolite. So far as the adjustment of the highest possible ion exchanger capacity is not important, the proportions used in the synthesis mixture within the framework of the invention with less than 45 mol H2O per mol of Al203 may be particularly preferred; in these a specially favourable space-time yield with at the same time extraordinary fine distribution and absence of agglomerates is observed.

Specially favourable proportions used for the adjustment to the highest possible exchanger capacity (determined as calcium binding power) are present with molecular proportions H2O/AI203 in the range between 45:1 and about 60:1.

When the reactants are mixed together a water-clear solution is first obtained at the beginning, which however, depending on whether the mixing temperature is more or less sudden, becomes cloudy and thickens to a gel-like form. A considerable increase of the viscosity of the reaction mixture thereby results, which however diminishes again when vigourous stirring is continued. The change of viscosity of the reaction mixture can be followed, for example, by means of the energy intake of the stirrer.

After the maximum viscosity is reached, the reaction mixture is taken from the reaction vessel to a comminuting apparatus, in which it is exposed to high cutting forces. The viscosity is thereby reduced to its minimum. It is preferably passed through the comminuting apparatus several times, for example 2-7 times, while, for example, the process may be carried out so that the suspension is passed back from the comminuting apparatus into the reaction vessel, where the reactant solutions, which at the beginning of the transfer of the suspensions from the reaction vessel to the comminuting apparatus have not yet been completely added, are addled in measured amounts. Then the reaction mixture is run again through the comminuting apparatus.

As already stated, the reaction velocity, i.e. the speed of the precipitation, is dependent on the temperature, the maximum viscosity is thus attained earlier or later according to the temperature and accordingly the decline of the viscosity after exceeding the maximum takes place more rapidly or more slowly depending on the temperature. For the removal of the reaction mixture from the reaction vessel and the transfer to the comminuting apparatus, this signifies that it is begun 1 to 120 seconds after the maximum viscosity is reached.

If, as is generally preferred, the mixing of reactants at temperatures in the range between 55 and 1000C, preferably between 60 and 85"C is effected, the maximum viscosity is reached extraordinarily quickly, so that it may be more suitable in some circumstances to control the process by means of certain time factors for the individual sections of the process, than by means of the control of viscosity. Thus the mixing of the reactants is generally effected within a period of 3 seconds to 5 minutes, preferably from 3 seconds to 2 minutes especially within a period of 4 to 60 seconds. Maintenance of the suitable reaction conditions is ensured when within 120 seconds, preferably in from about 0 to 60 seconds after the union of the amounts of reactants required calculated for the formation of half the amount of product provided has begun, as to lead the suspension obtained through the comminuting apparatus. The treatment in the comminuting apparatus is generally begun not later than 60 seconds after complete union of the reactants.

Used as comminuting apparatus are apparatus within the scope of the invention, which are used, for example, for the purpose of emulsifying a liquid with the other liquid which is not of itself miscible with the other liquid, or dispersing in liquid solids with low particle sizes. The phenomena which separate the action of comminuting apparatus in the meaning of the invention frqm simple stirrers, are: high cutting power, cavitation, torsional force or spin and turbulence. The comminuting apparatus used according to the invention are especially those in which cavitation occurs during the treating of liquids.

An example of a comminuting apparatus which may be used according to the invention is a high pressure homogeniser, with which the homogenising process in the so-called homogenising valves takes place, in which the mixture of liquids under high pressure and the suspension of silicate particles in aqueous medium under high pressure within the scope of the invention is released from pressure in sudden bursts, i.e. is subjected to a very much lower external pressure.

The comminuting apparatus used are especially those which make it possible to treat suspensions under conditions in which immiscible liquids such as water and benzene are emulsified with one another with formation of emulsions with a particle size between 0.1 and 10 , in the absence of surface-active compounds or naturally unstable emulsifiers.

An example of such homogenisers described above is the Gaulin homogeniser or high pressure homogeniser of the trade.

Other comminuting apparatus utilisable according to the invention, thus homogenising devices, are the so-called liquid mixers which consist of stator and rotor units. For example, the so-called multifrequency liquid mixers consist of a multistage system of stator plates and rotor discs, while the stator plates have bolthole circles, through which holes the mixing material flows in the axial direction. These holes lie sunk in annular channels arranged symmetrically on both sides of the stator plates. The sides of the channels may have specially constructed gears. In the channels run the likewise annularly arranged shearing pins of the rotor discs.

For inost uses of ion exchanger aluminium silicates crystalline products are preferred, and accordingly at the end of the recycling run of the suspension through a comminuting apparatus, the suspension is then preferably subjected to a crystallisation step. This consists in holding the suspension of the water-insoluble aluminium silicate after the comminuting step up to the adjustment of the desired, degree of crystallisation (as determined by X-ray diffraction analysis) of the suspended aluminium silicate at a temperature between 50 and 100"C, preferably between 70 and 95"C. It has also proved advantageous, if also by no means absolutely necessary, to supply no stirring energy or only very little, during the crystallisation step of the suspension. The continuous operation of the crystallisation step has proved favourable, in which there is added to the thixotropic suspensions in this stage preferably only just sufficient stirring energy for them to be kept just flowable or pumpable or transportable. Generally both with continuous and discontinuous operation of the crystallisation step, it is preferred to supply only sufficient stirring energy to the thixotropic suspension as is necessary for it to remain flowable or transportable.

The crystallisation is also accelerated by increase in temperature, so that it is expedient to raise the temperatures of the suspensions for the purpose of the crystallisation at least at times above the temperature being adjusted by the mixing of the aluminate and silicate solutions. A process is specially suitable for the crystallisation in which the temperature of the suspension is raised quickly, for example by blowing in steam or by external heating to a temperature at least 50C over the temperature achieved by the mixing of the aqueous solutions, preferably to 900 to 950C, and is held in this range of temperature up to the adjustment of the degree of crystallisation desired in the suspended aluminium silicate, or again can fall off to a temperature between 50 and 90"C and be held in this range up to the adjustment of the degree of crystallisation desired. The mixing of the aluminate and silicate solutions, which precedes the crystallisation step, may for example take place at 60 to 850C, preferably 600 to 700C.

Within the scope of the crystallisation step the suspensions may also be kept longer at elevated temperature than is necessary for the adjustment of the desired degree of crystallisation, because in some cases it is desired, to influence other properties of the suspension, for example the particle size distribution of the aluminium silicate particles. The period of the crystallisation step may lie between about 3 minutes and several hours. In connection therewith it has been surprisingly shown that with the described combination of measures in the process specially high values for the calcium binding capacity are obtained even with unusually short crystallisation times. Thus the time of the crystallisation step usually lies under 2 hours, and generally at 5 to 65 minutes.

After the-possibly repeated-treatment in the comminuting apparatus and, when provided for, the crystallisation step, the suspension may be cooled, whereupon the partial neutralisation provided of the suspension by washing out and/or addition of acid may take place. For the purpose of the partial neutralisation provided the suspension can be freed from a part of its content of excess alkali, for example by washing out. For this purpose the suspension is freed from at least a part of the mother liquor, for example by centrifuging or filtering off, on which water is added and possibly the now diluted mother liquor is again separated. The technique of displacement washing is particularly advantageous. The pH is generally adjusted to a value below 12.5. The suspensions, however, may also be treated with higher pH values to give washing and cleaning agents.

In the case of the partial neutralisation, obviously the concentration of the suspension may be affected. Basically the concentration can of course be adjusted to a small extent at will by addition of the necessary amount of water. A special advantage of the process of preparation according to the invention is, however, that aluminium silicate particles are obtained which show an unusually favourable suspension behaviour. Namely, there cannot only be prepared by way of comparison suspensions of low concentration with solid contents of for example 5 to 20 suspensions of middle concentrations of 20 to 300/n by weight, but also suspensions which at pH values between 7 and 11.5 are still able to be handled with solid contents in the range between 30 and about 53 /a by weight. In this range of concentration the advantages caused by the process of preparation are distinctly special, so that, when a later drying of the suspensions is intended and excess water thus is not desired, still liquid, directly pumpable suspensions according to the invention with solid contents above 35%, for example in the range from 37 to 50%, may be put in with special advantage. Under the term "Suspension" within the meaning of the invention fall of course also aluminium silicate/water-mixtures, which are no longer pumpable, thus mixtures which have a solid content of up to 60 or even up to 70% by weight.

When "Solid content" is spoken of here, the content of compounds of formula I is meant throughout. The solid content is found by filtering off the aluminium silicates of formula I, washing out carefully to a pH value of the wash water of 10, and then slowly drying for an hour at 800"C to remove the adhering water. A suspension according to the invention, which for example has a "solid content" of 31 /n by weight, thus contains by calculation 31 by weight of a separated and dried product described above, while in addition obviously further products may be present from the preparation which are solids in pure form, but on washing out are removed as water-soluble substances.

In general the pH value of the suspension after the comminuting step and possibly the subsequent crystallisation step is adjusted not only by washing out to values below 12.5 particularly between 11.5 and 12.5. On the contrary, it has been found advantageous to partially neutralise the suspension by addition of acid. For example, the aluminium silicate suspension may be washed out, until it has with a solid concentration of 30% by weight or more less than 5% excess alkali, and then is neutralised by addition of acid. It is preferred to wash out to an alkali content of 3% or less, especially 2% or less. The percentage data relate to the total weight of the suspension. The pH value of the suspension lies generally between about 6 and 11.5, mostly above 7 and preferably between 8 and 11.

Examples of free acids are especially the mineral acids, thus for example sulphuric acid, phosphoric acid or hydrochloric acid. Which individual acid is used for the neutralisation or partial neutralisation is essentially dependent on the use provided for the suspension. If, for example, the suspension is provided for the preparation of aluminium silicate-containing washing and cleaning agents, sulphuric acid is generally the chosen acid, since during the neutralisation sodium sulphate which is not objectionable in the washing process is formed.

On addition of acid a local excessive acidification of the suspension is to be avoided, since the products of the process are sensitive to free acids. Problems do not occur here however, since with good stirring and/or slow addition, local pH falls into the region in which the products are dissolved or damaged, may be avoided.

If the processing is to provide for washing and cleaning agents, it is particularly suitable to use as acid a substance whose water-soluble salts have surface-activity, especially washing activity. Suitable acids for the neutralisation are thus the anionic surface-active substances in their acid form, i.e. especially anionic surface-active substances of the sulphate and sulphonate type. These surface-active substances contain in the molecule at least one hydrophobic organic residue and mostly an aliphatic hydrocarbon residue with 8 to 26, preferably 10 to 22 and especially 12 to 18 carbon atoms or an alkylaromatic residue with 6 to 18, preferably 8 to 16 aliphatic carbon atoms. Suitable surface-active compounds of the sulphate type are alkylbenzene-sulphonates (Cg~,5-alkyl), mixtures of alkene- and hydroxyalkanesulphonates, as well as disulphonates, such as are obtained, for example, from monolefines with terminal or non-terminal double bond by sulphonation with gaseous sulphur trioxide and subsequent alkaline or acid hydrolysis of the sulphonation products. Alkanesulphonates are also suitable which are obtainable from alkanes by sulphochlorinatin or sulphoxidation and subsequent hydrolysis or neutralisation or by bisulphite addition to olefines. Further utilisable surface-active substances of the sulphonate type are the esters of a - sulpho - fatty acids, for example the a - sulphonic acids from hydrogenated methyl or ethyl esters of the coconut, palm kernel or tallow fatty acids.

Suitable surface-active substances of the sulphate type are the sulphuric acid monoesters of primary alcohols (for example from coconut fatty alcohol, tallow fatty alcohols or oleylalcohol) and of secondary alcohols. Furthermdre, sulphate fatty acid alkanolamides, fatty acid monoglycerides or reaction products of 1 to 4 mol of ethylene oxide with primary or secondary fatty alcohols alkylphenols are suitable.

Further suitable anionic surface-active substances, which in their acid form can be used for the neutralisation according to the invention, are the fatty acid esters or amides of hydroxy- or amino - carboxylic acids or sulphonic acids, as for example, the fatty acid sarcosides, glycolates, lactates, taurides or isothionates.

The use of anionic surface-active substances in their acid form for the neutralisation or partial neutralisation of excess alkali has proved specially advantageous insofar as the suspensions so prepared have a distinctly improved suspension stability, which is of considerable advantage for their further processing and also for their storage.

Further suitable compounds for the stabilisation of the suspensions, which are used as free acids, and thus are used for the partial neutralisation-but are obviously also utilisable in the form of point in aqueous butyldiglycol solution below 85"C (DIN 53917) are to be mentioned as stabilizing additives. These products have about 5 to 8 mol of ethylene oxide per mol of the phenol, while adducts with 6 to 7 mol ethylene oxide are preferred.

Single compounds which illustrate the above mentioned classes of non-ionic suspension agents are: lauric acid-, coconut fatty acid-, myristic acid-, palmitic acid-, stearic acid- and oleic acid-monoethanolamide; lauric-myristic acid diethanolamide, the diethanolamide of a fatty acid mixture of lauric and myristic acids, and oleic acid diethanolamide; an ethoxylation product of 5 mol of ethylene oxide per mol of a saturated alcohol or amine derived from tallow fatty acid, while the non-ethoxylated amine is also suitable; the adduct of 7 mol of ethylene oxide to nonylphenol.

As for the stabilizing, suitable compounds which have neither acid nor surface-active character, are the polymeric, preferably synthetic polyhydroxy compounds such as, for example, polyvinylalcohol.

If stabilizing additives are used within the scope of the invention, thus especially the above mentioned anionic or non-ionic surface-active substances, their amount in the suspensions according to the invention may be extremely low, while the desired stabilization is yet caused. This also is a special advantage of the invention. For example, stabilized suspensions, which are prepared according to the invention, have advantageously an aluminium silicate content between 30 and 55 ,4 by weight, and in such case a content of anionic and/or non-ionic surfaceactive substances in a range from 0.1 to 1% by weight. The concentrations may obviously deviate in one or other direction from that indicated, but the indicated range is usually distinctly preferred, especially the range from 0.2 to 0.7 /" by weight.

The suspensions prepared according to the invention are suitable for various uses in a special way. On the basis of the peculiarities of their preparation, especially by the combination according to the invention of quite specific proportions in the charge together with the unusually fast precipitation described and practically immediate further treatment, the suspensions already have stability and rheological properties which are considerably more favourable than the properties of aluminium silicate suspensions prepared in the customary way. These suspensions can therefore already be used, stabilized as such, as described above, for example, by addition of an anionic or nonionic washing substance, as liquid scouring agents, which have improved suspension stability. For use as liquid scouring agents, obviously further detergent substances or other usual components of such agents may be added, for example builder substances from the group of inorganic and organic complex-forming substances for the hardness-forming components of water.

A further in practice particularly important use of the suspensions according to the invention is their further processing to form pulverulent products with a dry appearance. Especially according to the invention the procedure is to subject the suspension to a spray drying, in which the suspension is sprayed by nozzles or is brought on to rotating discs and is thus finely divided, and the fine droplets formed during the spraying are dried in a stream of hot air. The products so obtained are marked by a specially favourable resuspension behaviour. Further, the pulverulent products obtained according to the invention are very suitable for use in washing and cleaning agents. Even in the case of the use described above, it is preferred to use the suspensions stabilised.

A particularly important use of the suspensions according to the invention is their further processing to give pulverulent washing and cleaning agents.

The present invention will now be further described by means of the following Examples.

Examples The calcium binding capacity of the aluminium silicates prepared in the Examples was determined in the following way: I litre of an aqueous solution containing 0.594 g of CaC12 (=300 mg CaO/litre=300dH) and adjusted with dilute NaOH to a pH value of 10 is treated with I g of aluminium silicate (referred to AS). Then the suspension is vigorously stirred for 15' at a temperature of 22"C (+2 C). After filtering off the aluminium silicate the residual hardness X of the filtrate is determined. The calcium binding capacity is calculated from this in mg CaO/g AS according to the formula: (30-x) . 10. To determine the residual hardness the calcium content is determined by titration with EDTA (see below).

The abbreviations used in the following pages signify: "TA+5EO" is a product of addition of 5 mol of ethylene oxide per mol of a substantially saturated fatty alcohol prepared by reduction of tallow fatty acid; "ABS" is the salt of an alkylbenzenesulphonic acid having about 11 to 13 carbon atoms in the alkyl chain obtained by condensing straight-chain olefines with benzene and sulphonation of the alkylbenzene thus formed; "OA+10 EO" is a product of addition of ethylene oxide to commercial oleyl alcohol in the molar ratio 10:1; "Waterglass" is a sodium silicate (Na2O:SiO2 calculated=l:3.35); "CMC" is the sodium salt of carboxymethylcellulose; "EDTA" is the tetrasodium salt of ethylenediaminotetraacetic acid; "Perborate" is a technical product of the approximate composition NaBO2 . H202 . 3H2O; "Salt" is the sodium salt of a hardened tallow fatty acid.

Example 1 1(A) In a precipitation vessel with a capacity of 60 litres 32 kg of an aluminate solution preheated to 600C showed the following calculated composition (molar ratio): Na2O:2.68; Awl203:1 0; H235.55.

10.0 kg of a sodium silicate solution, which was also preheated to 600 C, were added from a stock vessel with vigorous stirring with a propellor stirrer (670 rpm) in a period of 6 to 8 sec while the sodium silicate solution had a solid content of 35 /" by weight.

Altogether the sodium silicate solution corresponded to the composition (molar ratio): Na2O:0.52; Ski0,:1.80; H2O:l4.45 These molar quantities relate to the total amount of Al203 calculated present in the sodium aluminate solution, which was arbitrarily fixed at 1.0. The sum of the individual data for Na2O, Awl203, SiO2 and H2O thus gives the molar ratio, which is present in the reaction mixture after complete union of the reactants, here also: Na2O:3.2; Al203:1.0; Six2:1.8; H2O:50 Immediately after the end of the addition of the sodium silicate solution, the viscosity of the aqueous system is already beyond the maximum viscosity and decreases again. At this stage, the very highly viscous gel is immediately conveyed through a now open valve in the bottom of the reaction container of a homogenising apparatus (comminuting apparatus) of the stator/rotor type. In this case a comminuting apparatus of the "Supraton" type was used, Manufacturer: Firm Auer & Zucker, Federal Republic of Germany.

The amount rotated was about 1000 to 1500 litres/hour. During the treatment in the comminuting apparatus the viscosity decreased in order to reach a limiting value, which however lay distinctly above the viscosity of the aluminate or silicate solutions used.

During the drawing of the suspension through the comminuting apparatus, the remainder of the sodium silicate solution of the above given composition and temperature was in a period of 10 to 12 seconds fed into the precipitation container. Altogether approximately 20 seconds were needed for the complete union of the reactants. The final temperature in the reaction mixture was 70- 72"C.

After cycle of about 5 minutescirculation through precipitation containercomminuting apparatus-precipitation container-the suspension obtained, which even in this stage may be processed to washing and cleaning agents, was passed to a filter, while the mother liquor was partly removed-about 40% of the total water present. The filter residue was treated on the filter with fresh water until the water running off had a pH of 10. The solid product obtained corresponded to the formula 1.1 Na2O. 1.0 Awl203. 1.8 SiO2.

1(B) Alternatively, for the production of a fully crystalline product the suspension first obtained was transferred to a crystallisation vessel with a capacity of about 150 litres smaller vessel could be directly used. The temperature in the crystallisation vessel is immediately raised by blowing in steam at about 90"C, for which about 5 minutes are necessary. After reaching this temperature, the suspension is left without stirring for 30 minutes at about this temperature and then is passed to a filter. A considerable part of the mother liquor together with about 1/3 of the total alkali present is thereby removed. The amount of water removed is replaced twice by corresponding amounts of wash water, on which a filter residue of the composition 1.12 Na2O. 1.0 Al2O3. 1.8 SiO2.23 H2O is obtained. This product is stirred in a little water and the more dilute suspension obtained can be added by pumps directly to the washing agent production.

The product prepared as described above had a calcium binding capacity of 163 mg CaO/g of active substance. The grain size distribution was: 86/o < 5 8; 94/n < 10 8; 99/n < 20 y The aluminium silicate of the suspension described above showed 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(+) When the aluminium silicate is less strongly crystallised-i.e. lower degree of crystallinity-the intensity of these X-ray diffraction lines decreases. The strongest interference lines are characterised with a "(+)". All d-values are taken up with Cu K-radiation and given in ngstrm units ( ).

I(C) From the filter residue which is produced as described above and which contains crystalline sodium aluminium silicate, sodium aluminium silicate suspensions of the following compositions are produced, which are stabilized by mixing with water containing surfactants: (a) Sodium aluminium silicate 33 /n by weight; alkylbenzenesulphonic acid (sodium salt, C11-C13-alkyl) 0.5% by weight, (b) Sodium aluminium silicate 38 /n by weight; ethoxylation product of 5 mol of ethylene oxide with I mol of C,6~,8 fatty alcohol 0.5 by weight, (c) Sodium aluminium silicate 40 /n by weight; ethoxylation product of (b) 0.25 /n by weight, (d) Sodium aluminium silicate 35 /n by weight; poly - a - hydroxy - acrylic acid (molecular weight about 100,000) 0.5 by weight, (e) Sodium aluminium silicate 38 /n by weight; I - hydroxy - ethane - 1,1 diphosphonic acid 0.8 /n by weight.

In the case of the variants (d) and (e) the addition of the dispersing agent contributes to the partial neutralisation of the suspension.

Example 2 A suspension of crystallised sodium aluminium silicate was prepared as described in Example 1B, but with the difference, that it was only washed so far that the suspension still had a NaOH content of 1.15 and a solid content of 36.

The pH value of this suspension still lies above 13. It was now dosed with 20% aqueous sulphuric acid, with simultaneous stirring in an approximately 150 litre vessel, until the pH value had fallen into the range from 10.3 to 10.8. The suspension thus obtained had a sodium aluminium silicate content of 32% by weight, a content of sodium sulphate of 2.4% by weight and a pH value of 10.3. The calcium binding capacity of the sodium aluminium silicate was determined as 157 mg CaO/g of active substance. On microscopic inspection of the present sodium aluminium silicates, complete absence of undesired agglomeration of the primary particles to larger combinations was found.

Example 3 Suspensions of partly to wholly crystalline sodium aluminium silicates were prepared as described in Example 1, but with the changes given below, while the sodium aluminium silicates are characterised by their calcium binding capacity given in tabular form: Contents: 2.8 Na2O. 1.0 Al2O3. 1.8 Six2 .50 H2O Na2O At209 SiO2 H20 Sodium silicate solution 0.52 1.80 14.45 Sodium aluminate solution 2.28 1.0 35.55 Precipitation at 600C, Supraton driven in circuit for 5 minutes, within 5 minutes heated to crystallisation temperature (800 or 900) and crystallisation for a further 60 minutes while stirring. Final and intermediate samples were examined, while the suspensions after the crystallisation step as indicated were in each case washed out to a pH value between 9 and 11.5.

Crystallisation Temperature 800C Calcium Binding Capacity Crystallisation Time (Minutes) (mg CaO/g AS) 15 37 30 166 60 169 Crystallisation Temperature 90"C 15 145 30 171 60 173 Example 4 The procedure was as in Example 3, but with the following deviations: Contents: 2.8 Na2O. 1.0 Al203. 1.8 Six2 .60 H2O Na2O Awl203 SiO2 H20 Sodium silicate solution 0.52 1.80 14.45 Sodium aluminate solution 2.28 1.0 45.55 Precipitation at 600C, Supraton driven in circuit for 5 minutes, heated at 850C crystallisation temperature within 5 minutes and crystallised for a further 90 minutes while stirring. Final and intermediate samples were examined: Calcium Binding Capacity Crystallisation Time (Minutes) (mg CaO/g AS) 30 30 60 107 90 158 Example 5 The procedure was as in Example 3, but with the deivations indicated: Contents 3.2 Na2O. 1.0 Al203. 1.8 Six2 .44 H2O Na2O Al203 SiO2 H20 Sodium silicate solution 0.52 1.80 14.45 Sodium aluminate solution 2.68 1.0 29.55 Precipitation at 600 C, Supraton driven in circuit for 5 minutes, heated up to 900C crystallisation temperature within 5 minutes and crystallised for a further 60 minutes without stirring. Final and intermediate samples were examined: Calcium Binding Capacity Crystallisation Time (Minutes) (mg CaO/g AS) 0 124 15 116 30 112 60 106 Example 6 The procedure was as in Example 3, but with the deviations indicated: Contents: 3.2 Na2O. 1.0 Al2O3. 1.8 SiO2.60 H2O Na2O Al203 SiO2 H20 Sodium silicate solution 0.52 1.80 14.45 Sodium aluminate solution 2.68 1.0 45.55 Precipitation at 60 C, Supraton driven in circuit for 5 minutes, heated up to crystallisation temperature (800 or 90 C) within 5 minutes and crystallised for 60 or 90 minutes while stirring. Final and intermediate samples were examined: Crystallisation Temperature 80 C Calcium Binding Grain Size Distribution Crystallisation Time Capacity (Fractions in /n) (Minutes) (mgCaO/gAS) < lOp < 20p 30 59 60 148 96 99 90 162 98 99 Crystallisation temperature 900C 15 105 30 161 98 99 60 163 99 > 99 Example 7 The procedure was as in Example 3, but with the deviations indicated: Contents: 3.6 Na2O. 1.0 Al2O3. 1.8 SiO2. 50 H2O Na2O Al2O3 SiO2 H20 Sodium silicate solution 0.52 1.80 14.45 Sodium aluminate solution 3.08 1.0 35.55 Precipitation at 60 C, Supraton driven in circuit for 5 minutes, heated up to crystallisation temperature (700 C) and crystallised for a further 45 minutes while stirring. Final and intermediate samples were examined: Crystallisation Temperature 70 C Calcium Binding Grain Size Distribution Crystallisation Time Capacity (Fractions in /n) (Minutes) (mgCaO/gAS) < 10,u < 20p 15 165 87 97 30 166 95 99 45 167 96 99 Example 8 The procedure was as in Example 3, but with the deviations indicated: Contents: 3.6 Na2O. 1.0 Al2O3. 1.8 SiO2.70 H2O Na2O Al203 SiO2 H20 Sodium silicate solution 0.52 1.80 14.45 Sodium aluminate solution 3.08 1.0 55.55 Precipitation at 60"C, Supraton driven in the circuit for 5 minutes, heated up to 900C crystallisation temperature and crystallised further for 90 minutes while stirring. Final and intermediate samples were examined: Calcium Binding Grain Size Distribution Crystallisation Time Capacity (Fractions in /n) (Minutes) (mgCaO/gAS) 5p 10 20p 30 163 60 165 45 99 > 99 90 164 52 99 Example 9 The procedure was as in Example 3, but with the deviations indicated: Contents 3.2 Na2O. 1.0 Al2O3. 1.8 SiO2.70 H2O Na2O Al2O3 SiO2 H20 Sodium silicate solution 0.52 1.80 14.45 Sodium aluminate solution 2.68 1.0 55.55 Precipitation temperature varies between 10 C and 90"C.

Crystallisation Temperature at 90-95 C Calcium Binding Precipitation Crystallisation Time Capacity Temperature ( C) (Hours) (mg CaO/g AS) 10 1.5 148 30 1.0 158 45 1.0 161 2.0 170 2.0 158 60 1.0 157 2.0 162 2.0 159 75 1.0 163 2.0 169 90 0.5 128 Example 10 Pulverulent, pourable washing agents of the composition indicated in Table 1 were prepared as follows: a standard suspension, which had been prepared by introducing the filter-residue prepared according to Example 1B and partly neutralised to a pH value of about 10.5, into a dispersion heated to about 70 C of an hydrogenated tallow fatty alcohol ethoxylated with 5 mol of ethylene oxide per mol of the alcohol, and a conent of 40% by weight of aluminium silicate and 0.5 by weight of the dispersing agent-in each case referred to the total weight of the suspension-was pumped from a stock vessel into a container, in which then the other components and water were successively introduced while stirring, the water being such that a washing agent slurry containing about 45% by weight of water was formed. This was fed through pumps to the spray nozzles situated at the top of a spraying tower and by spraying and passing in countercurrent to hot air (ca. 260 C) converted into a fine powder.

A B ABS 1.4 TA+ 10 EO 7.0 OA+ 10 EO 8.0 /n TA+5 EO'2' 2.7% Sodium triphosphate 7.8% Sodium triphosphate 20.0 / Waterglass 5.4 Soda 5.0% CMC 0.8 /n Waterglass 3.0 /n Aluminium silicate(1)(AS) 36.0% CMC 1.8% TA+5 EO"' 0.45% Aluminium silicate''' (AS) 18.0% Remainder water and TA+5 EO(1) 0.23 /n Na2SO4 EDTA 0 5 /n MgSiO3 2.5% Perborate'3' 28.0% Soap 2.5% Remainder water and Na2SO4 (2) TA+5 EO with the remaining components added (1) with standard suspension introduced (3) after the addition of the spraying.

Instead of a suspension stabilised with TA+5 EO suspensions can also be used in the production of a corresponding washing agent B which contain, for example polyacrylate. Since polyacrylate is a substance forming complexes with calcium, the sodium triphosphate fraction can be correspondingly reduced. In the preparation of ABS-containing washing agents an ABS-containing suspension according to the invention may be used, while in a concrete case an ABS with 11 to 13 carbon atoms in the alkyl residue is used.

Example 11 An aqueous suspension containing about 40 /n by weight of aluminium silicate prepared according to Example IA was sprayed in a hot stream of air and thereby dried, i.e. freed from adhering water. The pulverulent aluminium silicate obtained is very suitable as a water-softening agent and as a washing agent builder substance.

The procedure is of special advantage which is as described above, but with a suspension, which is composed as given in Example 1Ca, but the aluminium silicate content is 40% by weight, or corresponds to Example lCc. In these cases special products with little dust are obtained, which are also very suitable as water softening agents and as washing agent builder substances.

WHAT WE CLAIM IS: 1. A process for the preparation of an aqueous suspension of a finely divided water-insoluble silicate capable of cation exchange and still containing bound, water, of the general formula; (Kat2O)08~,.3. (Al2O3) . (SiO2)r 7s-20 (I) in which Kat represents an alkali metal cation which comprises mixing an aqueous solution of an alkali metal aluminate or the reactants which will produce an alkali metal aluminate in situ and an aqueous solution of an alkali metal silicate or the reactants which will produce an alkali metal silicate in situ, in which the calculated total composition of the aqueous solutions with respect to their Awl203 and their SiO2 content corresponds to formula I above, but that the aqueous solutions in total contain not more than 80 mol of water per mol of Al203 of the formula and contain an excess of alkali such that in total at least 2.5 mol of Kat2O is present per mol of Awl203, and in which at least part of the aqueous solutions to be mixed are mixed rapidly with vigorous stirring and the suspension obtained further vigorously stirred, and in which when the viscosity of the suspension so obtained has reached a maximum value and begun to fall again, the suspension is passed through a comminuting apparatus, and thereafter adding rapidly and with vigorous stirring to the suspension a measured quantity or repeated measured quantities of any unmixed aqueous solutions, followed after each such addition by further vigorous stirring and at the aforesaid viscosity level passing the solution through a comminuting apparatus, until all the aqueous solutions to be mixed have been mixed.

2. A process as claimed in Claim 1 in which the further vigorous stirring is on each occurrence continued until the viscosity level of the suspension has reached a maximum value and begun to fall again but is discontinued before a minimum viscosity level is reached.

3. A process as claimed in Claim 1 or 2 in which the calculated total composition in respect of Al203 and SiO2 content of the aqueous solutions to be mixed corresponds to the composition of the desired silicate product.

4. A process as claimed in Claim 1 or 2, in which the Al2OWSiO2 ratio is 1:1.8 to 1:1.9.

5. A process as claimed in any of Claims 1 to 4, in which Kat represents a potassium, or sodium, ion.

6. A process as claimed in any of Claims 1 to 5, in which the solutions are mixed at a temperature in the range between 55" and 100"C, while the aluminate solution or the silicate solution or both solutions are used preheated to a temperature in the given range.

7. A process as claimed in Claim 6, in which the temperature of mixing is between 60 and 85"C.

8. A process as claimed in any one of Claims 1 to 7, in which the alkali metal silicate solution has a molar ratio of SiO2/Kat2O in the range from 2 to 4.

9. A process as claimed in Claim 8, in which the molar ratio of SiO2/Kat2O in the alkali metal silicate solution is from 2.2 to 3.8.

10. A process as claimed in any one of Claims 1 to 9 in which after all the aqueous solutions to be mixed have been mixed and the suspension passed through

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

the sodium triphosphate fraction can be correspondingly reduced. In the preparation of ABS-containing washing agents an ABS-containing suspension according to the invention may be used, while in a concrete case an ABS with 11 to

13 carbon atoms in the alkyl residue is used.

Example 11 An aqueous suspension containing about 40 /n by weight of aluminium silicate prepared according to Example IA was sprayed in a hot stream of air and thereby dried, i.e. freed from adhering water. The pulverulent aluminium silicate obtained is very suitable as a water-softening agent and as a washing agent builder substance.

The procedure is of special advantage which is as described above, but with a suspension, which is composed as given in Example 1Ca, but the aluminium silicate content is 40% by weight, or corresponds to Example lCc. In these cases special products with little dust are obtained, which are also very suitable as water softening agents and as washing agent builder substances.

WHAT WE CLAIM IS: 1. A process for the preparation of an aqueous suspension of a finely divided water-insoluble silicate capable of cation exchange and still containing bound, water, of the general formula; (Kat2O)08~,.3. (Al2O3) . (SiO2)r 7s-20 (I) in which Kat represents an alkali metal cation which comprises mixing an aqueous solution of an alkali metal aluminate or the reactants which will produce an alkali metal aluminate in situ and an aqueous solution of an alkali metal silicate or the reactants which will produce an alkali metal silicate in situ, in which the calculated total composition of the aqueous solutions with respect to their Awl203 and their SiO2 content corresponds to formula I above, but that the aqueous solutions in total contain not more than 80 mol of water per mol of Al203 of the formula and contain an excess of alkali such that in total at least 2.5 mol of Kat2O is present per mol of Awl203, and in which at least part of the aqueous solutions to be mixed are mixed rapidly with vigorous stirring and the suspension obtained further vigorously stirred, and in which when the viscosity of the suspension so obtained has reached a maximum value and begun to fall again, the suspension is passed through a comminuting apparatus, and thereafter adding rapidly and with vigorous stirring to the suspension a measured quantity or repeated measured quantities of any unmixed aqueous solutions, followed after each such addition by further vigorous stirring and at the aforesaid viscosity level passing the solution through a comminuting apparatus, until all the aqueous solutions to be mixed have been mixed.
2. A process as claimed in Claim 1 in which the further vigorous stirring is on each occurrence continued until the viscosity level of the suspension has reached a maximum value and begun to fall again but is discontinued before a minimum viscosity level is reached.
3. A process as claimed in Claim 1 or 2 in which the calculated total composition in respect of Al203 and SiO2 content of the aqueous solutions to be mixed corresponds to the composition of the desired silicate product.
4. A process as claimed in Claim 1 or 2, in which the Al2OWSiO2 ratio is 1:1.8 to 1:1.9.
5. A process as claimed in any of Claims 1 to 4, in which Kat represents a potassium, or sodium, ion.
6. A process as claimed in any of Claims 1 to 5, in which the solutions are mixed at a temperature in the range between 55" and 100"C, while the aluminate solution or the silicate solution or both solutions are used preheated to a temperature in the given range.
7. A process as claimed in Claim 6, in which the temperature of mixing is between 60 and 85"C.
8. A process as claimed in any one of Claims 1 to 7, in which the alkali metal silicate solution has a molar ratio of SiO2/Kat2O in the range from 2 to 4.
9. A process as claimed in Claim 8, in which the molar ratio of SiO2/Kat2O in the alkali metal silicate solution is from 2.2 to 3.8.
10. A process as claimed in any one of Claims 1 to 9 in which after all the aqueous solutions to be mixed have been mixed and the suspension passed through

the comminuting apparatus, the suspension is maintained at an elevated temperature until at least partial crystallization has taken place.
11. A process as claimed in Claim 10 in which the suspension of the waterinsoluble aluminium silicate is maintained at least up to the desired degree of crystallisation of the suspended aluminium silicate at a temperature between 50 and 100 C.
12. A process as claimed in Claim 11, in which the temperature is between 70" and 95"C.
13. A process as claimed in Claim 11 or 12, in which after the last treatment in the comminuting apparatus the suspension for the crystallisation step is heated by blowing in steam at a temperature which is at least 50C above the temperature achieved by the mixing of the aqueous solutions, when the mixing of the aqueous solutions is effected in the temperature range between 60 and 85"C.
14. A process as claimed in Claim 13, in which the suspension is heated by blowing in steam at a temperature of from 90 to 950C.
15. A process as claimed in any one of Claims 10 to 14, in which during the crystallisation step of the suspension which is thixotropic at this stage, only sufficient stirring energy is supplied in order to keep the suspension flowable and/or pumpable.
16. A process as claimed in Claim 15, in which the mixing of aluminate and silicate solutions is carried out at a temperature in the range from 60 to 700 C, the temperature then is quickly raised to 90--950C and is maintained at this temperature, or allowed to cool to a temperature between 50 and 90"C until the degree of crystallisation of the suspended alkali metal aluminium silicate has been adjusted to the desired level.
17. A process as claimed in Claim 16, in which the temperature is quickly raised to 90 to 950C by blowing in steam.
18. A process as claimed in any one of Claims 1 to 17, in which during the mixing of the aqueous solutions an amount of alkali is introduced so that 2.8-3.8 mol of Kat2O/mol of Al203 are present.
19. A process as claimed in Claim 18, in which during the mixing of the aqueous solutions an amount of alkali is introduced so that 3.0 to 3.6 mol of Kat2O/mol of Al203 are present.
20. A process as claimed in any one of Claims 1 to 19, in which the amount of water in the aqueous solutions is such that less than 75 mol of water/mol of Al203 are present.
21. A process as claimed in Claim 20, in which the amount of water in the aqueous solutions is such that 45-60 mol of water/mol of Al203 are present.
22. A process as claimed in any one of Claims 1 to 21, in which the suspension of an aluminium silicate is prepared which has a calcium binding capacity over 50 mg CaO/g of active substance.
23. A process as claimed in Claim 22, in which the aluminium silicate suspension has a calcium binding capacity of 100 to 200 mg CaO/g of active substance.
24. A process as claimed in any one of Claims 1 to 23, in which the suspension is passed through the comminution apparatus 2 to 7 times.
25. A process as claimed in any one of Claims I to 23, in which the treatment in the comminuting apparatus is begun 1 to 120 seconds after the suspension has attained the maximum viscosity.
26. A process as claimed in any one of Claims 1 to 25, in which the mixing of the aqueous solutions is effected at temperatures in the range between 55" and 100 C over a period of 3 seconds to 5 minutes, whereupon within 0 to 120 seconds after combination of the amounts of reactants calculated to be necessary for the formation of half the amount of product envisaged treatment of the suspension in the comminution apparatus is commenced.
27. A process as claimed in Claim 26, in which the mixing of the aqueous solutions is effected at temperatures in the range between 60 and 85"C over a period of 3 seconds to 2 minutes whereupon within 0 to 60 seconds after combination of the amounts of reactants calculated to be necessary for the formation of half the amount of product envisaged treatment of the suspension in the comminution apparatus is commenced.
28. A process as claimed in Claim 27, in which the aqueous solutions are mixed over a period of 4 to 60 seconds.
29. A process as claimed in any one of Claims I to 28, in which the comminution apparatus is suitable for the preparation of emulsions of liquids not miscible with one another, and the treated liquids or suspensions are exposed to a cavitation action, in which the homogenising process takes place in homogenising valves, in which the suspension or liquid standing under high pressure is suddenly de-pressurised, thus is exposed to a considerably lower exterior pressure; the homogenising apparatus consisting of stator and rotor units, in which the stator plates have holes, which may be arranged with respect to bolthole circles, through which the liquid or suspension to be treated flows in an axial direction, while the recessed holes lie in annular channels arranged symmetrically on both sides of the stator plates, and the annularly arranged shearing pins of the rotor discs run in the channels.
30. A process as claimed in any one of Claims 1 to 29, in which the suspensions after the treatment in the comminuting apparatus and the optional crystallisation step are adjusted to a pH value below 12.5 by washing out excess alkali, removal of at least a part of the adhering mother liquor and at least partial replacement by water, and/or by addition of an acid.
31. A process as claimed in any one of Claims I to 30, in which the pH value of the first obtained, still strongly alkaline suspension is reduced by washing out to a pH value between 11.5 and 12.5 and then is adjusted to a pH value in the range from 6 to 11.5, by addition of an acid.
32. A process as claimed in Claim 31, in which the pH of the suspension is adjusted to between 8 and 11.
33. A process as claimed in any one of Claims 30 to 32, in which the acid used is sulphuric acid, phosphoric acid, hydrochloric acid or another cqmponent of washing and cleaning agents present in acid form.
34. A process as claimed in Claim 33, in which an anionic surface-active sulphate or sulphonate is used for the neutralisation.
35. A process as claimed in Claim 33, in which the acid used is a polymeric polycarboxylic acid with a di- or poly-phosphonic acid.
36. A process as claimed in Claim 35, in which the polycarboxylic acid has a molecular weight above 20,000.
37. A process as claimed in any one of Claims 1 to 36, in which the suspensions are stabilised by addition of an anionic surface-active sulphate or sulphonate as water-soluble salts, by addition of a polymeric, polyhydroxy compound, or by addition of a non-ionic surface-active substance, which has a turbidity point, determined according to DIN 53917 in aqueous butyl-diglycol solution, between 40 and 85"C.
38. A process as claimed in Claim 37 in which the polymeric polyhydroxy compound is polyvinyl alcohol.
39. A process as claimed in Claim 35, in which the polymeric polycarboxylic acid is synthetic.
40. A process as claimed in Claim 37, in which the non-ionic surface-active substance has a turbidity point between 55" and 85"C.
41. An aqueous suspension suitable for further treatment to give washing and cleaning compositions, of the silicates defined in Claim 1, prepared by a process as claimed in any one of Claims 1 to 40.
42. Washing and cleaning compositions whenever produced from an aqueous suspension as claimed in Claim 41.
43. A process as claimed in Claim 1 and substantially as hereinbefore described with reference to any one of the Examples.
44. An aqueous suspension as claimed in Claim 41 and substantially as hereinbefore described with reference to any one of the Examples.
45. A washing and cleaning compositIon as claimed in Claim 42 and substantially as hereinbefore described with reference to any one of the Examples.