FR2523950A1 - Zeolite suspension with static and dynamic stability - obtd. by neutralising suspension, adding organic polymer dispersant e.g. CMC and shearing - Google Patents

Abstract

Zeolite suspension having good static and dynamic stabilities and good fluidity, is prepd. by:- (1) neutralising an aq. cake or suspension contg. water and a zeolite in a form such that these cannot be separated by filtration with an (in)organic acid or its corresponding anhydride or salt, so that the pH of the zeolite suspension after adding the acid, anhydride or salt is 9.5-12 and the pH after adding the acid etc. and allowing to stand is 11.3-12.7; (2) adding a water-soluble or -dispersible organic polymeric dispersant at the rate of at least 0.1 wt.% w.r.t. anhydrous zeolite to the neutralised zeolite suspension, and (3) subjecting the obtd. suspension to strong shear. The zeolite suspension is also claimed. The zeolite suspension also has a relatively low viscosity at room temp. It is used for the prepn. of detergents in which agglutination, pptn. and deterioration of the zeolite particles are prevented under static or dynamic conditions.

Description

 The invention relates to a process for preparing an aqueous zeolite suspension having excellent stability, particularly with regard to the combination of static stability and dynamic stability and which has a relatively low viscosity even at normal temperatures and which has good fluidity. The invention also relates to a process for preparing a zeolite builder suspension which can advantageously be used for the manufacture of detergents.

 It has long been known that a water-insoluble alkali metal aluminosilicate, such as a zeolite, exhibits excellent metal ion sequestering capacity and has a high buffering effect and a good effect of inhibiting the recontamination of the metal. alkaline conditions and that a water-insoluble alkali metal aluminosilicate can be effectively used as a detergent builder due to these excellent characteristics.

 However, various problems in the manufacture and transport of zeolite additives remain to be solved.

A zeolite is a substance having an expansive character and it is difficult to sufficiently remove water from a crystallized zeolite by filtration and if the zeolite filter cake is allowed to stand without exerting any external force, this filter cake is transformed. in a pasty product. Therefore, to obtain a dry zeolite powder, it is necessary to use expensive drying modes, such as spray drying. The zeolite particles tend to agglomerate upon drying, but from the viewpoint of the adjuvant characteristics, it is preferred that the zeolite particles be as small as possible. Therefore, the spray drying product of a zeolite must be subjected to a spray treatment whose duration is important. In addition, the dry powder zeolite very fine particles is very bulky and therefore the cost of transport s Increases and the working environment is polluted by the spread of the powder when handling or transporting this zeolite powder in very fine amounts.

 In order to overcome the aforementioned drawbacks caused by the handling of the zeolite powder, a method has been adopted in which a crystallized zeolite is handled in the form of an aqueous suspension. However in this case also other problems remain to be solved. The zeolite particles tend to precipitate in water and when an external force is applied by vibrations or the like during transport, the particles agglomerate to form a very hard precipitation cake. Thus, when handling a zeolite in the form of an aqueous suspension, it is common that even unloading a zeolite from a container becomes difficult.

 Many attempts have been made to obtain an aqueous liquid containing a zeolite. In these tests, various dispersing surfactants were used to prevent the precipitation of the zeolite particles. For example, a process is known in which a water-soluble polymer containing a carboxy group, such as carboxymethylcellulose, a laminar clay swelling under the effect of the invention, is added as a stabilizing agent to an aqueous suspension of zeolite. water such as a bentonite or a nonionic surfactant such as an ethylene oxide addition compound of a higher alcohol (see US Pat. No. 4,072,622), a process in which in combination with an aqueous suspension of zeolite, to obtain a stabilizing effect, a water soluble alkali metal salt such as sodium carbonate and a nonionic surfactant (see Japanese Unexamined Patent Application No. 155200 / 79) and a process in which an organic flocculating agent such as polyacrylamide, polyacrylic acid or acrylic acid copolymer (see published Japanese Patent Application No. 84533/80) is added to an aqueous suspension of zeolite.

 These known methods are still insufficient in that when a dispersion stabilizer as indicated above is added to an aqueous suspension of zeolite, the viscosity of the suspension increases enormously and that for this aqueous suspension remains fluid, it is necessary to maintain it at a high temperature or to carry out a permanent gentle stirring. Moreover, these known processes have the disadvantage that the effect of inhibiting the precipitation of the particles, when the aqueous suspension obtained is allowed to stand in stationary conditions, ie thermal stability, and the effect of inhibiting particle precipitation, when the aqueous suspension is allowed to stand under dynamic conditions, i.e. with application of vibrations or other external forces caused by transport, are unsatisfactory.

Japanese Patent Application Publication No. 64504/79 discloses an aqueous suspension of precipitation stabilized zeolite which is formed by dispersion of
zeolite in an aqueous solution of sodium silicate. This aqueous suspension has good stability during
short-term storage, but when stored for extended periods, a type A zeolite is transformed into a Pc-type zeolite or analcime, the ion-exchange capacity is considerably reduced and precipitation and agglutination become important.

 The main object of the present invention is to provide an aqueous suspension of zeolite which has excellent stability, in particular an excellent combination of static stability and dynamic stability, and which has a relatively low viscosity even at ordinary temperatures and which has good fluidity.

 It is also an object of the invention to provide an aqueous zeolite suspension for the manufacture of detergents in which agglutination, precipitation and deterioration of the zeolite particles can be prevented effectively under static or dynamic conditions and the high stability of the suspension of zeolite fines and the excellent properties of a detergent builder can be stably maintained in a low viscosity form.

 The invention also relates to a process for preparing the above-mentioned aqueous suspension of zeolite according to a relatively simple and inexpensive operation.

 The invention thus provides a process for preparing a zeolite slurry having excellent static stability and dynamic stability and having good fluidity, wherein an aqueous cake or an aqueous slurry containing water and a zeolite under water is neutralized. in such a form that they are substantially inseparable from one another by filtration with an inorganic or organic acid or an anhydride or corresponding acidic salt so that the pH of the zeolite suspension upon completion of the addition said acid, acid anhydride or acidic salt is in the range of 9.5 to 12 and the pH of the zeolite suspension in the stationary state after the addition of said acid, acid anhydride or acidic salt is included in the range of from 11.3 to 12.7, a water-soluble or water-dispersible organic polymer dispersant is added at least 0.1% by weight based on the anhydrous zeolite to the suspension. neutralized zeolite then the resulting suspension is subjected to stirring with high shear.

The invention will be better understood on reading the description which follows and on examining the appended drawings in which
FIG. 1 is a titration curve illustrating the relationship between the amount of hydrochloric acid added (meq / 100 g of annular zeolite on the abscissa) and the pH (on the ordinate) which is observed when it is added progressively. 20% hydrochloric acid (6.04 N) at a flow rate of about 2.1 ml / min to 500 g of the base zeolite suspension Al used in Example 1 (having an anhydrous zeolite concentration). 40.6%, a free alkali concentration of 0.28%, a density of 1.352 measured at 250C and a viscosity of about 94 cP measured at 250C); ; and
FIG. 2 is a curve showing the variation of the pH (ordinates) over time (hours, on the abscissa) observed when 10.2, 13.3 or 20.2 are added dropwise. ml of 20% hydrochloric acid at a rate of 4.5 ml / min to the above suspension Al to form a suspension having a pH of 12.2, 11.0 or 9.5 and the suspension obtained is allowed to stand.

 The preferred embodiments of the invention will now be described in detail.

One of the important features of the process of the invention lies in the discovery that, when a zeolite is neutralized in the form of an aqueous suspension with an inorganic or organic acid or an anhydride or acidic acid salt
than the reactants (often referred to as "acid" hereinafter) for the pH (P1) of the zeolite suspension upon completion of the addition of the acid is in the range of 12 to 9.5, 11.5 to 10, and the pH (P2) of the zeolite suspension in the stationary state after the addition of the acid, for example 4 hours after the moment of addition of the acid, is in the range of 12.7 to 11.3, in particular 12.5 to 11.5 and the difference between the values P1 and P2 is preferably in the range of 0.7 to 1.3, the stability of the suspension can be remarkably improved virtually without increasing its viscosity.

 The alkali (Na) ions present in the aqueous zeolite slurry are roughly divided into the following three types: (a) alkali ions dissolved in the aqueous phase, (b) alkali ions incorporated into the crystal structure of the zeolite particles and (c) the alkaline ions present at the interface between the zeolite particles and the aqueous phase. When titrating an aqueous suspension of zeolite with an acid such as hydrochloric acid and that a graph is drawn where the amount of hydrochloric acid added and the pH of the suspension are represented respectively on the abscissa scale. and the ordinate scale, a curve similar to that illustrated in FIG. 1 is obtained. As shown in FIG. 1, the portion (a) with a gentle slope in the high pH region corresponds to the free alkaline ions (a) present. in the aqueous phase, the gently sloping portion (b) in the low pH region corresponds to the alkaline ions (b) incorporated in the crystal structure of the zeolite particles and the relatively large portion (c) lying between the portions a and b correspond to the alkaline ions (c) present at the interface between the zeolite particles and the aqueous phase. In practice, the smaller the size of the dispersed zeolite particles, the greater the amount of added hydrochloric acid corresponding to the portion (c) of the titration curve.

 When an aqueous suspension of zeolite at various pHs is neutralized with an acid such as hydrochloric acid, and the changes in pH are examined over time, a pH-time curve similar to that obtained is obtained. illustrated in FIG. 2. The results illustrated in FIG. 2 show that when the neutralization is carried out in a pH region corresponding to the free alkaline ions (a), there is no significant difference between the pH at the time of stopping the neutralization and the pH after a certain time has elapsed, while when performing the neutralization in a pH region corresponding to the portions c or b of the titration curve, the pH of the suspension increases over time after the completion of the addition of the acid to finally cap at a value above the pH observed upon completion of the addition of the acid and it is also seen that when the neutralization is carried out in a corresponding pH region spawning at portion b of the titration curve, the subsequent pH rise is greater than that observed when the neutralization is performed in the pH region corresponding to the portion (c) of the titration curve.

 The pH region in which the zeolite suspension is neutralized with the acid according to the invention is between the portions a and b of the abovementioned titration curve. Thus in this pH region the alkali metal ions incorporated in the crystal structure of the zeolite particles are substantially neutralized but all of the free alkali metal ions in the zeolite slurry and at least a portion of the alkali metal ions present on the surface of the zeolite particles are neutralized.

 If neutralization of the zeolite slurry with the acid is carried out so that the pH is within the above range upon completion of acid addition, the slurry stability of the zeolite particles is remarkably improved without an abnormal increase in the viscosity of the final suspension. More particularly, when the pH at the time of completion of the addition of the acid is too high and exceeds the above range, it is difficult to adjust the pH of the final suspension in the range specified in the invention and even if a water-soluble dispersant is added to this neutralized suspension, the static stability of the suspension is impaired and when the suspension is allowed to stand for 1 to 4 days, precipitates agglomerated zeolite particles which coagulate by adhering to the container.When the pH at the time of completion of the addition of the acid is too low and less than the ga As mentioned above, it is difficult to adjust the pH of the final suspension to the range indicated in the invention and if a water-soluble organic dispersant is added to the neutralized suspension, the dynamic stability of the suspension is impaired. and when the suspension is stirred for 16 hours or more, substantial agglutination of the precipitated particles is formed.

 It is also apparent from the following description that to prepare a zeolite slurry having excellent stability and low viscosity, it is important to neutralize the zeolite with an acid so that the above-mentioned pH conditions are met. As previously indicated, it is known that the stability of a slurry of zeolite particles can be improved by the addition to this slurry of a water-soluble alkali metal salt. However, if the alkali metal salt is added to a zeolite slurry in an amount sufficient to prevent agglutination and precipitation of the zeolite particles, the slurry viscosity increases abnormally to, for example, 10,000 cP. or more at ordinary temperatures, and the slurry virtually loses fluidity at ordinary temperatures. When it is desired to manipulate this suspension in the fluid state, it must be maintained at a temperature greater than 300 which constitutes an undesirable operation.

This tendency is also observed when a nonionic surfactant is added to a zeolite slurry to stabilize it. This is evident from the fact that an alkali metal salt or a nonionic surfactant in aqueous solution is surrounded by a layer consisting of a large amount of water. In contrast, the suspension of the zeolite prepared according to the process of the invention has a relatively low viscosity of 50 to 5000 cP at 20oC and has a good fluidity suitable for handling and also the suspension of the zeolite according to the invention. excellent stability.

 When a slurry of zeolite is washed several times to remove the alkali metal component to adjust the pH of the slurry to the above range, even when adding a water-soluble organic dispersant to this slurry, the static stability of the suspension is very low and after one day only highly agglomerated particles precipitate. This shows that to improve the stability of the slurry, it is important that the alkali metal component contained in the zeolite slurry is neutralized with a predetermined amount of the acid so that the pH is within the range indicated in the invention. .

 The reason why the stability of the suspension of the zeolite particles is greatly improved in the invention by neutralization of a zeolite suspension with the acid so that the pH is within the aforementioned range, has not been fully elucidated. . However, it appears that in the acid neutralized zeolite slurry, there is a water-soluble salt formed by the reaction of the alkali metal component and the acid and that this water-soluble salt improves the stability. However, because in the invention a remarkable effect of improving the stability of the suspension can be obtained with an amount of alkali metal salt which is soluble in water less than that of a metal salt. water-soluble alkali added from the outside to the suspension, it appears that the physical and chemical properties of zeolite particle surfaces are modified and that the improvement in the stability of the suspension is mainly due to these changes in the properties of chemical and physical.

As previously indicated, when the neutralization conditions specified in the invention are adopted, all of the free alkali metal ions and at least a portion of the alkali metal ions of the surfaces of the zeolite particles are neutralized and if let stand this neutralized suspension the pH rises over time. This apparently indicates that the alkali metal (Na +) ions on the surfaces of the zeolite particles are substituted by the hydrogen ions (H) of the liquid phase. It appears that in the invention the proton surface zeolite particles are in stable suspension and that this stability of the suspension is increased by the water-soluble alkali metal salt present in the liquid phase and the subsequently added polymer dispersant.

 As a slurry of zeolite used as starting material in the invention, there may be mentioned a slurry formed by stirring a wet cake during the process of producing a zeolite. Generally, to prepare a zeolite, a homogeneous liquid composition containing alumina, silicic acid and alkali metal components and water is formed in the zeolite formation ratio and the composition is heated. homogeneous to crystallize the zeolite. The zeolite filter cake is obtained by subjecting the liquid containing the crystallized zeolite to filtration, centrifugal separation, liquid elimination treatment using a filter press, a belt filter, a drum filter, leaf filter or centrifugal separator.

 Due to its expansive character, this filter cake contains a considerable amount of water which can not be separated by filtration or centrifugation. According to the invention, the zeolite particles are suspended using this residual water as dispersion medium.

The concentration of the zeolite particles in the starting slurry is such that this slurry substantially contains this inseparable water. More particularly, the concentration of the zeolite expressed in the anhydrous state is from 30 to 50% by weight, in particular from 37 to 45% by weight. If the concentration is too high and falls outside the indicated range, the viscosity of the suspension is too high and handling of the suspension is difficult. On the other hand, if the concentration is too low and below the indicated range, a supernatant separates easily and it becomes difficult to achieve the objectives of the invention. In addition, in this case, it is necessary to transport and handle an excessive amount of water which has economic disadvantages.

 In the invention it is preferred that in the starting zeolite slurry the free alkali concentration of the mother liquor is 0.1 to 1.0% by weight, in particular 0.2 to 0.7% by weight. by weight, this concentration being determined according to the method described below. If the amount of the free alkali metal component is too small and less than the above range, even when performing the neutralization treatment, it is difficult to improve the stability of the suspension to a satisfactory value. and if the amount of the free alkali metal component is too large and falls outside the above range, the viscosity of the final suspension becomes too high and handling of the suspension becomes difficult.

 The invention is applicable to aqueous suspensions of various synthetic zeolites and can be particularly advantageously applied to zeolites for detergent builder. With regard to the sequestering capacity of metal ions, it is preferred that the CaO (exchange capacity) binding capacity of a zeolite for detergent builder be at least 100 mg / g, in particular 120 at 180 mg / g, calculated as anhydrous zeolite.

 The zeolite metal ion sequestering capacity differs according to the nature of the crystalline structure, and it is known that a Type A zeolite has the highest capacity followed by the capacity of an X-type zeolite while Y-type zeolite has the lowest capacity. In the invention, it is preferred that the zeolite used be composed only of type A zeolite or a mixture of type A zeolites and type X or Y zeolites.

 The invention is applicable to any zeolite particles having a primary particle size (measured with an electron microscope) of at least 1 μ, but particularly good results are obtained when applying the invention to zeolite fine particles having a primary particle size of less than 1 lum.

A zeolite having such fine particles has a high rate of ion exchange and has the excellent properties that adjuvants must possess. However, its tendency to agglomeration is important and the viscosity of a suspension of such fine particles is much greater than the viscosity of a suspension of zeolite particles having a larger size, the comparison being made for the same concentration of material. dried. According to the invention, even if such zeolite fine particles are used, a zeolite slurry can be obtained in which the primary particles do not tend to agglomerate, the viscosity of which is relatively low and the we can handle very easily.

 A fine particle zeolite that can be advantageously used to achieve the objects of the invention is a zeolite prepared according to the process described in US Pat. No. 4,102,977 which comprises treating an acid with a smectite clay. under conditions such that at least the X-ray diffraction peak of index (001) substantially disappears, to form an activated silicic acid or an activated aluminosilicic acid, the treatment of activated silicic acid or aluminosilicic acid activated with an alkali metal hydroxide or a water-soluble alkali metal silicate to form an alkali metal or polyaluminosilicate alkali metal polysilicate having a molar ratio of 20: SiO 2 in the range of 1: 3.5 to 1: 500, adding an additional alumina component and an alkali metal component and water to the alkali metal polysilicate or alkali metal polyaluminosilicate to form a homogeneous composition. wherein the respective components are contained in a ratio corresponding to the formation of a type A zeolite and heating the homogeneous composition to crystallize a fine particle zeolite having a primary particle size of less than 1 μm.

 In the invention, it is preferred to use directly as the starting slurry the wet cake obtained in the above method of producing a zeolite. In addition, a suspension having a higher concentration obtained by adding a dry zeolite powder to this wet cake can be used. Also, as the starting material in the invention, an aqueous suspension formed by dispersing a dry zeolite powder in water is used.

 In the invention, the zeolite suspension, a mineral acid, an organic acid or an anhydride or corresponding acidic salt is used to neutralize. Examples of inorganic acids are carbonic acid, sulfuric acid, sulphurous acid, hydrochloric acid, hydrobromic acid, hypochlorous acid, chloric acid, boric acid, nitric acid, phosphoric acid, phosphorous acid and metaphosphoric acid. Examples of organic acids are acetic acid, propionic acid, oxalic acid, citric acid, tartaric acid, succinic acid, maleic acid and malic acid. gluconic acid, -itaconic acid, thioglycolic acid, ethylenediaminetetraacetic acid, nitrilotriacetic acid, diglycolic acid, sulfo-itaconic acid, trimellitic acid, and pyromellitic acid. Examples of acid anhydrides include carbon dioxide (carbon dioxide), gaseous sulfur dioxide, chlorine, acetic anhydride and succinic anhydride. Examples of acid salts include sodium bicarbonate, sodium hydrogen sulfite and sodium dihydrogen phosphate. The acid can be added directly to the zeolite slurry, but it is generally preferred to gradually add the acid as an aqueous solution to the zeolite slurry with stirring.

 Among the various acids mentioned above, gaseous carbon dioxide is particularly preferred. Gaseous carbon dioxide behaves like an acid when it is dissolved in water and converted into carbonic acid. The other acids may react with the zeolite particles prior to reaction with the free alkali metal component of the slurry which causes a local drop in the pH of the slurry. This risk does not exist in the case of carbon dioxide. Thus carbon dioxide is particularly suitable for the treatment of the invention. In addition, when carbon dioxide is used for the neutralization, the stability of the final zeolite slurry is remarkably improved compared to the case where other acids are used. carbon to the suspension by insufflation of carbon dioxide gas in the zeolite suspension.

 It suffices to add the acid to the zeolite suspension in an amount such that the above-mentioned pH is obtained. More particularly, the amount of added acid is selected in the range of 7 to 45 meq / 100 g, particularly 8 to 20 meq / 100 g, relative to the anhydrous zeolite, for the pH to be within the aforementioned range. .

 Another characteristic of the invention is that the neutralized suspension thus obtained is mixed with a water-dispersible or water-dispersible organic polymer dispersant in a proportion of at least 0.1% by weight, in particular of 0.15 to 2% by weight relative to the anhydrous zeolite and that the suspension is subjected to stirring with high shear. Although the aforementioned neutralized zeolite suspension exhibits excellent static stability, agglomeration or precipitation of the zeolite particles is caused under dynamic conditions, for example under the effect of external forces, such as vibrations. However, if the polymer dispersant is incorporated in the neutralized suspension according to the invention, the dynamic stability can be remarkably improved.

 Examples of water-soluble or water-dispersible organic polymer dispersants are water-soluble polymers having at least one carboxy, hydroxy or ether radical, such as carboxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydroxymethylcellulose, various starches, cyanoethylated starch, carboxymethylated starch, sodium alginate, gum tragacanth, gum arabic, strong glue, casein, gelatin, alcohol polyvinyl alcohol, partially hydrolysed polyvinyl acetate, partially acetalized polyvinyl alcohol, polyvinyl methyl ether, vinyl methyl ethyl ether / maleic acid copolymer, polyvinylpyrrolidone, polyacrylamide and water-soluble acrylic resin. These organic dispersants can be used singly or in the form of a mixture of two or more. To achieve the objectives of the invention, it is particularly preferred to Previous organic dispersants, polymers having both a carboxy radical and a hydroxy radical such as carboxymethylcellulose and carboxymethylated starch.

 From the point of view of the stability of the final slurry, it is important to incorporate the organic polymeric dispersant in an amount of at least 0.1% by weight based on the anhydrous zeolite. If the amount of dispersant exceeds 2% by weight, the viscosity of the suspension is likely to increase. It is therefore necessary to avoid the incorporation of such a large quantity of dispersant.

 In the invention, the incorporation of the organic polymer dispersant into the above-mentioned neutralized suspension makes it possible to improve the dynamic stability of the zeolite particles. The reason for this phenomenon is considered to be the following.

 As previously described, it is considered that protons are present at extremely high concentrations on the particle surfaces of the suspension which has been neutralized under the above conditions. On the other hand, the organic polymeric dispersants contain a polar group behaving as an acceptor due to the existence of a hydrogen bond such as a carboxy, hydroxy or ether radical. Therefore, in the slurry of the invention it is considered that a hydrogen bond or other bond is formed between the zeolite particles and the polymeric dispersant and that under this binding the zeolite particles are stabilized against the precipitation, even if an external dynamic force is applied to the suspension.In the case of a dispersant such as carboxymethylcellulose, it is considered that the presence of many carboxy radicals play an important role in the dissolution and dispersion and many hydroxyl radicals capable of effectively forming hydrogen bonds with the zeolite particles of the suspension makes it possible to obtain a particularly excellent dispersion stability.

 The water-soluble polymeric dispersant may be added as a powder, solution or dispersion. To avoid dilution of the slurry, it is generally preferred to add the water-soluble polymer dispersant as a powder.

 In order to form a stabilized final suspension from the slurry into which an organic dispersant has been incorporated, it is important to subject the slurry to which an organic dispersant has been stirred with high shear. Shear agitation can be achieved for example with a colloid mill, a homogenizer, a dispersion mill, a dispersion mixer, a grinding mill or the like. The stirring is carried out under conditions such that the peripheral speed of the blade or rotor causing the shear is at least 10 m / s and in particular at least 15 m / s.

 The aqueous suspension of zeolite obtained according to the invention contains 30 to 50% by weight, in particular 37 to 45% by weight, of zeolite, in anhydrous zeolite, with respect to the total suspension, 7 to 45 meq / 100 g, in particular 8 to 20 meq / 100 g of the alkali metal salt of the mineral or organic acid relative to the anhydrous zeolite and at least 0.1% by weight, in particular 0.15 to 2% by weight water soluble or water dispersible organic polymer dispersant relative to the anhydrous zeolite.This suspension has a relatively low pH of 12.7 to 11.3, in particular 12.5 to 11.5 and a relatively low viscosity of 50 to 5000 cP, in particular 80 to 2000 cP, measured at 200 C. In addition the suspension has a good fluidity suitable for operations such as transport, unloading and feeding, even at ordinary temperatures. In addition, the suspension of the invention is advantageous in that when subjected to the static stability test and the dynamic stability test described in detail below, no precipitate is formed or in case a precipitate forms, the precipitated solids are only in the form of traces.

 Since the alkali metal salt and the polymeric dispersant contained in the suspension according to the invention are components usually used for a detergent composition, when using the suspension of this zeolite of the invention as a detergent builder, the incorporation of an undesirable ingredient in the detergent composition can be avoided.

In addition, since the additive that is used in the invention does not cause a bubbling phenomenon unlike a surfactant, the formation of bubbles is limited during the preparation operation or during transport and the handling of the suspension is greatly facilitated.

 In addition, the alkali metal salt and the polymeric dispersant which are contained in combination in the slurry of the invention provide excellent spray drying granulation characteristics when using the zeolite slurry of the invention as the base for the slurry. producing a granular detergent and a granulated product having good dispersibility and high resistance to powder fragmentation can be obtained.

 The invention is illustrated by the following nonlimiting examples.

EXAMPLE 1
In this example, a synthetic zeolite slurry for a detergent builder is prepared using an acid clay produced at Nakajo-machi, Niigata-ken, Japan, as a smectite clay.

The acidic starting clay produced at Nakajo-machi,
Niigata-Ken, Japan, which is used in this example, contains 45% by weight of water as collected and the main ingredients in relation to the dry products it contains are 72.1% by weight of SiO 2, 14.2% by weight of Al 2 O 3, 3.87% by weight of Fe 2 O 3, 3.25% by weight of MgO and 1.06% by weight of CaO, the loss on ignition being 3.15% by weight. The acidic clay is shaped into cylinders having a diameter of 5 mm and a length of 5 to 20 mm and 1,250 kg of shaped clay (dry product) is introduced into a lead-coated wooden container having a diameter of 5 mm. capacity of 5 m 3 and 3400 l of an aqueous solution of sulfuric acid having a concentration of 47% by weight are added to the clay. The mixture is heated to 90 ° C. and the acid treatment of the clay in the granular state is carried out for 40 hours.

By decantation using a dilute aqueous solution of sulfuric acid and water, a salt of sulfuric acid of a basic component reacted with sulfuric acid is washed off and the mixture is washed at room temperature. water until no more sufluric radical is detected to obtain an acid-treated granular clay. This acid-treated product is hereinafter referred to as "activated silicic acid" and contains 50% water.

 To prepare a zeolite, water is added to the activated silicic acid so that the concentration is 20% and the wet silicic acid is sprayed wet with a ball mill to obtain a suspension A of the activated silicic acid.

796 kg of the suspension thus obtained are introduced into a stainless steel container having a capacity of 2 m 3 and 46.6 kg of a commercially available solution of sodium hydroxide (containing 49% of NaOH) are added to the suspension. The mixture is stirred at 600C for 6 hours to obtain a suspension of an alkali metal polysilicate corresponding to
Na2O.8.8 SiO2.

To prepare a synthetic zeolite for detergent builder, the molar ratios of the following ingredients (expressed in oxides) are chosen
Na2O / SiO2 = 0.9
SiO2 / Al2O3 = 2.0
H2O / Na2O = 50.0
As a solution to be added to the alkali metal polysilicate slurry to achieve the above mole ratios, an alkali metal aluminate solution formed by adding and dissolving a commercial aluminum hydroxide to a commercial solution of caustic soda.

This solution contains 18.54% Na2O, 19.1% Au2O3 and 62.4% H2O and the molar ratio Na2O / Al2O3 is 1.6 / 1.

Process for preparing a synthetic zeolite for detergent builder

 Water is added to the alkali metal polysilicate slurry so that the SiO 2 concentration is 10% and the slurry is introduced into a stainless steel vessel having a capacity of 3.5 m 3. Water is added to the above-mentioned alkali metal aluminate solution to form a solution having a Na2O concentration of 12.5% and an Al203 concentration of 12.8. At 200C this solution is added with stirring to the suspension in about 80 minutes. The mixture temporarily passes to the gel state and finally a homogeneous suspension is obtained. The slurry was heated to 950C and reacted for 5 hours with stirring to form crystalline zeolite particles. The reaction product was washed with a slurry and filtered and the water was removed sufficiently to obtain a filter cake (having a in water of 59.4% relative to the anhydrous zeolite obtained by drying at 8000 C).

 About 100 kg of the resultant filter cake is then introduced into a 100 liter stainless steel vessel equipped with a stirrer and stirred to form a slurry having a solids content of 40% by weight.

1 kg of this zeolite suspension is then introduced
Al (having a pH of 13.2 measured at 200 ° C. and a free alkali content of 0.28 S) in a stainless steel vessel, and an aqueous sulfuric acid solution having a stirring amount is added dropwise to the suspension while stirring. concentration of 20% by weight at a flow rate of 4.8 ml / min. After addition of 11.1 ml of the solution, the pH of the zeolite suspension is 11.0. When the suspension is allowed to stand, the pH rises and stabilizes after 4 hours. At this time the pH of the suspension is 12.2.

 This suspension H1 is mixed with 0.5% by weight, relative to the anhydrous zeolite, of carboxymethylcellulose (CMC NO 1150 supplied by Daicel KK) and the mixture is subjected to a dispersion treatment using a domestic mixer to obtain a suspension. 1-1 zeolite having improved stability.

 Separately, sulfuric acid is added to the above-mentioned Al suspension so that the pH is 12.8, 11.6, 10.3 or 9.4, and the stabilized samples H-2, 1-2, are obtained. 1-3 and H-3.

 For each sample, the pH, viscosity, static stability, dynamic stability, zeolite concentration calculated as dry product, zeolite primary particle size, calcium exchange capacity, and rate of flow are determined. exchange. The results obtained are shown in Table 1.

 For comparison, 0.5% of carboxymethylcellulose is added directly to suspension A-1 and the mixture is subjected to the dispersion treatment to obtain a sample A-4.

 Samples H-1 to H-4 are comparative samples.

(See Table 1 on pages 35 and 36).

The physical properties shown in Table 1 are determined by the following methods (1) pH measurement of the suspension
100 ml of the sample suspension are introduced into a glass beaker and a glass electrode (associated with a reference electrode and a thermometer) is immersed in the sample and the pH is read after 3 minutes at 200 ° C. As a pH meter, we use the HM5A model supplied by Toa Denpa KK

(2) Viscosity measurement (with a type B viscometer):
The sample suspension is introduced into a beaker having a capacity of 1000 ml ensuring that the suspension does not contain air bubbles. The temperature of the suspension is adjusted to 200 ° C. and the measuring rotor of a type B viscometer is immersed in the suspension. so that the mark coincides with the liquid level of the suspension. The rotor is rotated at 20 rpm for one minute and the torsion of the spring is read on the scale.

The value read by the rotor factor is multiplied and the viscosity is expressed in centipoises (cP).

(3) Static stability measurement
In a 1000 ml wide-necked flask having an inside diameter of about 95 mm and a height of about 150 mm, 750 ml of suspension sample is introduced, the flask is capped and the suspension is allowed to settle in a room. maintained at 252C for 96 hours. Then, 5 experts determine whether a supernatant has formed or not, whether or not a precipitate has formed at the bottom of the suspension and what is the consistency of the precipitate. The static stability of the suspension is evaluated according to the following scale. ,
Evaluation Note Nature of assessment 10 no supernatant, no precipitate
9 trace of supernatant, no precipitate
8 about 5% by volume of supernatant, not
precipitate
7 about 5% by volume of supernatant, trace
of precipitate
6 about 5% by volume of supernatant, precipitated
covering all the substance and adhering to a
glass rod
About 5% by volume of supernatant, about
3% by volume of precipitate in which a
glass rod sinks
About 5% by volume of supernatant, about
5% by volume of precipitate in which a
glass rod sinks
3 about 5% by volume of supernatant, about
8% by volume of precipitate in a part of
what a glass rod does not sink.

2 about 8% by volume of supernatant, about
15% by volume of precipitate in which a
glass rod does not sink
About 15% by volume of supernatant, about
20% by volume or more of precipitate in the
what a glass rod does not sink.

(4) Measurement of dynamic stability
150 ml of suspension sample are placed in a clear 150 ml wide-mouthed flask having an inside diameter of about 60 mm and a height of about 60 rpm, the flask is capped and secured to the tray of a machine. of agitation (Eyela Shaker Mini SS-80 supplied by Tokyo Rika
Kikai KK). The suspension sample was shaken with horizontal amplitudes of 50 mm in the x direction and 30 mm in the y direction at the rate of 68 stirrels per minute for 16 hours. The presence of a supernatant is sought and the suspension is decanted off in the upper portion of the flask. Then 5 experts determine whether or not a precipitate is formed and what is the consistency of the precipitate. The dynamic stability is evaluated according to the following scale.

Evaluation score Nature of assessment 10 no precipitate
9 no precipitate, but some resistance
is felt when moving a rod of
glass on the bottom surface
8 no precipitate, but a clear resistance
is felt when moving a rod of
glass on the bottom surface but when in
cline the bottle all the content flows
7 precipitate adhering to the glass rod, resis
felt on the glass rod
6 when the glass rod sinks into the con
held, it reaches the bottom, but a precipitate
considerable solid is present that is not
evacuated when tilting the bottle
About 3% by volume of the precipitate indicated in 6
above
4 about 5% by volume of the precipitate indicated in 6
above
3 very dense precipitate in which a stem of
slightly hard
glass does not sink and covered with a layer
2 about 10% by volume of dense precipitate which
is not covered with a slightly hard coat
1 about 20% by volume of dense precipitate which
is not covered with a layer
tough.

(5) Measuring the amount of alkali metal component
free
A suspension sample is filtered with a filter paper (filter paper No. 6 for analysis, supplied by Toyo
Roshi KK) to obtain a filtrate and accurately weighs about 10 g of filtrate as gold. with a 0.05 N solution of hydrochloric acid using methyl orange as an indicator (changing to pH 3.1-4.4). The amount of free alkali metal component is expressed by the Na 2 O concentration (% by weight) of the filtrate.

(6) Measurement of the concentration of anhydrous zeolite
A sample of about 5 g of suspension is placed in a platinum crucible and calcined in an electric muffle furnace maintained at 800 ° C. for 60 minutes. The concentration of anhydrous zeolite is calculated from the weight of the residue.

(7) Primary particle size measurement (Dp)
The sample is observed with an electron microscope in a form in which the particles are sufficiently dispersed and the length of the edge of a directly measured cubic particle is chosen as the size of the primary particles (Dp). This size of the primary particles is determined according to the following procedures.

 A suitable amount of a fine powder sample is placed on a glass plate and a paraffin wax or petrolatum is added to the sample in a volume substantially equal to the volume of the sample. The mixture is thoroughly kneaded with a small stainless steel spatula. A small amount of ethanol is added to the kneaded mixture and kneaded thoroughly on the glass plate. The kneaded mixture is placed on an electron microscope measurement grid and immersed in ethanol to dissolve the paraffin wax or the like and the residue is dried in a desiccator maintained between 60 and 700 ° C for 1 hour to evaporate the ethanol.

 Usually, the observation is carried out under the electron microscope with a direct magnifying power of 1000 to 2000 and a photographic enlargement of 10 and four photographs taken under an electron microscope with a magnification of 10,000 to 20,000 are made suitable for measuring the size of the primary particles that varies in the field of view.

 Six typical particles are chosen from the cubic particles present in the field of observation and the length of the edge considered to be practically parallel to the plane of the field of view (grid plane) is measured for each selected particle. The maximum value measured is used as the size of the primary particles (Dp).

(8) Measurement of calcium exchange capacity
A sample is accurately weighed so that the amount of anhydrous zeolite is about 0.5 g and introduced into a 1500 ml beaker. Deionized water is then added so that the volume contained in the beaker is exactly 250 ml. A 250 ml hard water (200 ° C) containing 600 mg / l CaO, prepared using CaC12 reagent grade, is dispersed thoroughly with a magnetic stirrer and beaker.

The mixture is stirred for 10 minutes and filtered immediately on a filter paper (# 6 paper supplied by Toyo
Roshi KK). 20 ml of filtrate are accurately taken and diluted with deionized water to bring the volume to about 100 ml. 2 to 3 ml of the Dotite NH3-NH4-Cl reagent and 0.5 ml of a 0.01 M solution of Zn-EDTA are then added to the solution. It is titrated with a standard 0.01 M EDTA solution using the Dotite BT reagent (Black Eriochrome T) as an indicator, and the calcium exchange capacity (mg of CaO per gram of anhydrous zeolites) is calculated according to US Pat. following equation calcium exchange capacity (CaO mg / g = 300 - 28 x C x F
2a x B / 100
where a is the weight (g) of the sample,
b is the content of anhydrous zeolites (%), C is the volume
delivered me (ml) of the 0.01 M solution of EDTA and F is
the titrimetric factor of the 0.01M solution of EDTA.

(9) Measurement of the rate of exchange of calcium ions
Hard water containing about 300 mg / l of
CaO (hydrotitrimetric titre = 43, CaO content = 214.3 mg / l) and the pH was adjusted to 10.0 with 0.1 N solution
NaOH. 500 ml of calcium-containing solution are then introduced into a 1-liter beaker and heated to 300 ° C., and the solution is then stirred with a stirrer (magnetic stirrer model A-2 supplied by Mitamura Co. Ltd). Separately, 0.500 g of the sample which has been dried for 2 hours in a thermostatically controlled desiccator maintained at 1100 ° C is weighed accurately with a constant relative sensitivity and direct reading balance and the sample is projected into the solution containing the aforesaid calcium. The mixture is subjected to one of the following three treatments (a), (b) and (c).

 (a) The mixture is stirred for 30 seconds after contacting the sample with the calcium-containing solution and the mixture is immediately filtered with a No. 6 filter paper. The time of contact between the sample and the solution containing calcium is practically 1 minute.

 (b) The mixture is stirred for 90 seconds and filtered immediately as in (a) above. The contact time between the sample and the calcium-containing solution is almost 2 minutes.

 (c) The mixture is stirred for 150 seconds after the sample is thrown and filtered immediately as in (a) and (b) above. The contact time between the sample and the calcium-containing solution is almost 3 minutes.

10 ml of accurately measured filtrate are then collected and diluted with deionized water to bring the volume to about 50 ml. 4 ml of 8N KOH are then added to the dilution to adjust the pH to 12. A few drops of 5% KOH and then 0.1 g of Dotite NN indicator are added. The title is then titrated with a 0.01 N aqueous solution of EDTA. The measured values are taken on a semi-logarithmic paper, the best matching line is drawn and the coefficient is calculated.
K the rate of exchange of calcium ions from the slope of this line according to the equation given below.

In the case where the exchange rate is too fast and the concentration determined after 1 minute of contact is almost the same as the concentrations determined after 2 minutes and 3 minutes, the contact time is adjusted between 10 and 20 seconds and perform the measurement again to determine the K value.

in which CO is the concentration (mg / ml) of the ions
Calcium (CaO, mg / l) in hard water starting, C is the
concentration (mg / l) of calcium ions (CaO) in the
filtrate collected after calcium ion exchange, t
is the time (minutes) of calcium and K ion exchange
is the rate of exchange of calcium ions (mn-1/2
EXAMPLE 2
Carbon dioxide was blown at a rate of 1 l / min in 1 kg of the zeolite suspension Al obtained in Example 1 and after about 3 minutes of insufflation, the pH was 11.0. The zeolite suspension is then allowed to stand for 4 hours and the pH is 12.1.

 As described in Example 1, carboxymethylcellulose was added at 0.5% relative to the anhydrous zeolite to the above zeolite suspension, and the suspension was subjected to dispersion treatment with a domestic mixer to form a 2-1 zeolite suspension having improved stability.

 Carbon dioxide is blown into the aforesaid suspension A-1 so that the pH is 12.6, 11.5> 10.5 or 9.6.

The neutralized samples H-5, 2-2, 2-3 and H-6 are thus prepared.

 On each sample, the properties described in Example 1 are determined. The results obtained are shown in Table 2.

 The amount of carbon dioxide (meq / 100 g anhydrous zeolite) was determined according to the following procedure.

 After 4 hours have elapsed after the addition of the carbon dioxide, 3 g of the suspension are accurately weighed and introduced into a Schrotter alkalimeter for the analysis of the gaseous carbon dioxide. Usually, 6N hydrochloric acid is added dropwise and the gaseous CO2 formed is introduced into a gas chromatograph (supplied by Shimazu Seisakusho KK, Polapack column, 3m, 400C) to determine the amount of CO2. and the number of milli-equivalents (meq) of CO2 per 100 g of the anhydrous zeolite contained in the suspension is determined.

(see table 2 on page 37),
EXAMPLE 3
In this example, the neutralization treatment is carried out using nitric acid, hydrochloric acid, acetic acid, citric acid, oxalic acid, hydrochloric acid + oxalic acid. or carbon dioxide + nitric acid.

 The suspension of zeolite A-1 obtained in Example 1 is introduced into seven stainless steel containers and in each container the neutralization treatment is carried out.

In the case of the mixture of hydrochloric acid + oxalic acid, a mixed acid solution is prepared from 25 g of 20% hydrochloric acid and 50 g of 10% oxalic acid and this mixed acid solution is used for the neutralization. .

In the case of the carbon dioxide + nitric acid mixture, carbon dioxide is blown into the zeolite suspension with stirring until the pH of the suspension is 12 and then 20% nitric acid is added to the slurry. the suspension so that the pH is 11.

 Carboxymethylcellulose is then added at a level of 0.5% based on the dry weight of zeolite to each neutralized suspension and the suspension is then subjected to a dispersion treatment with stirring to form a zeolite suspension having improved stability.

 For each sample, the properties described in Example 1 are determined. The results obtained are shown in Table 3.

(see table 3 on page 38).

EXAMPLE 4
In this example, the neutralization treatment is carried out using sodium hydrogencarbonate, which is an acidic salt.

 To 1 kg of the suspension A-1 prepared in Example 1 is added 4.26 g of commercial sodium hydrogen carbonate of reactive quality. The pH of the suspension after the addition of the neutralizing agent is 11. 0.25 g of carboxymethylcellulose are then added to the neutralized suspension and the suspension is subjected to dispersion treatment using a domestic mixer to form a suspension. of zeolite (sample 4-1) having improved stability.

 For comparison, a comparative sample (H-7 or H-8) is prepared as described above except that sodium carbonate is used in the neutralization treatment instead of sodium hydrogencarbonate.

The properties of each sample are determined. The results obtained are shown in Table 4 (page 39)
EXAMPLE 5
In this example, the effects of carboxymethyl starch, sodium alginate, and vinyl alcohol are examined as water soluble polymer dispersants.

 In a 2-liter stainless steel container, 1 kg of the zeolite A-1 slurry prepared in Example 1 is introduced and an aqueous 20% sulfuric acid solution is added dropwise to the slurry to form a slurry. zeolite suspension having a pH of 11. 0.25%, based on the zeolite suspension, of a dispersant indicated in Table 5 is then added with stirring to obtain a zeolite suspension having a static stability. and excellent dynamic stability.

 The properties described in Example 1 are determined for each sample. The results obtained are shown in Table 5 (page 40).

EXAMPLE 6
In this example, the influence of the anhydrous concentration of the zeolite slurry is examined.

A dilute alkaline solution having a concentration of 0.67% Na 2 O or a zeolite powder of the same type is added.
Naa Trade (supplied by Mizusawa Industrial Chemicals,
Ltd) having a crystal particle size of 0.8 to the Zeolite Al slurry prepared in Example 1 for the slurry to have the anhydrous zeolite concentration shown in Table 6. A suspension solution was then added to the slurry. 20% hydrochloric acid so that the pH is 11.0. 5 g of carboxymethylcellulose are then added to 1 kg of the suspension thus treated and the suspension is subjected to a dispersion treatment using a domestic mixer. The properties described in Example 1 are determined for each sample. The results obtained are shown in Table 6.

TABLE 6
Samples of Samples
Comparative invention
Sample NO 6-1 6-2 6-3 6-4 6-5 H-9
Concentration (% of anhydrous zeolite) 31.2 34.7 37.9 43.1 46.9 20.5
Viscosity (cP at 200, C) after the 43 101 163 332 938 24 preparation
Static stability 5 7 9 10 10 2
Dynamic stability 6 7 8 10 10 2
Calcium exchange capacity (mg / g 170 170 170 170 170 170 anhydrous zeolite)
EXAMPLE 7
In this example, a synthetic zeolite for detergent builder was prepared using as the starting silicic acid component sodium silicate having an SiO 2 / Na 2 O molar ratio of 2.5 from a siliceous clay (gypsum) produced in Kagoshima. -Ken, Japan, commercial caustic soda and sodium aluminate and prepared from the synthetic zeolite thus obtained a zeolite suspension having excellent static stability and dynamic stability.

 In a 100-liter stainless steel container equipped with a heating device, 11.2 kg of the above-mentioned sodium silicate (having a Na2O content of 8.9% and an SiO2 content of 21.5%) are introduced. 30 kg of water are added with stirring. 22.7 kg of a sodium aluminate solution (having a Na 2 O concentration of 14.7% and a concentration of Al 2 O 3 of 15%) are then gradually added to the mixture to form a suspension of sodium aluminosilicate gel. . The suspension is allowed to mature with stirring at room temperature for 24 hours, the temperature is raised to 900 ° C. and a crystallization reaction is carried out under these conditions for 8 hours to obtain a crystalline zeolite.

The molar ratios of the ingredients in the crystallization reaction are as follows
Na2O / SiO2 = 1.75
SiO2 / A12O3 = 1.2
H2O / Na2O = 42.7
The crystalline zeolite thus obtained is separated from the mother liquor by filtration and washed with water and the water is removed to obtain 13 kg of a zeolite cake of the following type.
NaA having a water content of 60% relative to the anhydrous zeolite obtained by drying at 8000C and a pH of 13.2 measured at 200C. The free alkali content of the zeolite cake is 0.67%.

 The resultant filter cake is stirred in a stainless steel vessel equipped with a stirrer to form a suspension. Carbon dioxide was blown at a rate of 10 l / min into the zeolite slurry with stirring for about 5 minutes to obtain a zeolite slurry having a pH of 11.0. When this zeolite suspension is allowed to stand for 4 hours, the pH is 12.2.

As described in Example 1, carboxymethylcellulose is added to the suspension at a rate of 0.5% with respect to the anhydrous zeolite and the suspension is subjected to dispersion treatment with a colloid mill (Micolloid).
L provided by Tokushu Kika Kogyo KK) to obtain a zeolite suspension (Sample 7-1) having excellent static stability and dynamic stability. The properties thus described in Example 1 are determined on the sample thus obtained. The results obtained are shown in Table 7.

TABLE 7
Sample of
the invention
Sample 7-1
Viscosity (cP at 200C) after preparation 395
Static stability 9
Dynamic stability 9
Primary particle size of zeolite (lm) 1.2
Calcium exchange capacity (mg / g anhydrous zeolite) 169
EXAMPLE 8
In this example, the influence of the free alkali metal component is studied.

 The zeolite cake obtained in Example 1 was washed well with distilled water to obtain a suspension having a free alkali content of 0.056% or 0.11%.

In addition, reactive grade caustic soda was added to the slurry of zeolite A-1 prepared in Example 1 to form a suspension having a free alkali content of 0.61%, 0.96% or 1.20%. %. Carbon dioxide was blown into the suspensions with free alkali contents of 0.11%, 0.61%, 0.96% and 1.20% to form neutralized suspensions.

 Each suspension is mixed with carboxymethylcellulose at a rate of 0.5 relative to the anhydrous zeolite and then subjected to a dispersion treatment with a domestic mixer.

 The properties described in Example 1 are determined for each of the suspensions obtained. The results obtained are shown in Table 8.

TABLE 8
Sample Samples
Comparative invention
Sample NO 8-1 8-2 8-3 H-10 H-ll
Neutralizing agent nature CO2 CO2 CO2 non CO2 2
Amount (meq / 100 g anhydrous zeolite) 4.9 27.5 43.2 0 54.0
Content of the alkali metal of the suspension 0.11 0.61 0.96 0.056 1.20 of starting zeolite
Viscosity (cP at 200C) 215 336 895 201 2310 after preparation
Static stability 7 10 10 4 10
Dynamic stability 8 10 10 7 6
Primary zeolite particle size 0.8 0.8 0.8 0.8 0.8
Calcium ion exchange capacity 170 170 168 168 168 (mg / g anhydrous zeolite)
EXAMPLE 9
In this example, the stabilization treatment is carried out with various commercial type-A zeolites having different crystalline particle sizes. More particularly, one selects and uses (1) NaA-type zeolite powder (supplied by UCC), (2) NaX-type zeolite powder (supplied by UCC), (3) NaA-type zeolite powder (provided by by Toyo Soda KK), (4) a NaA-type zeolite powder (supplied by Degussa) and (5) a NaA-type zeolite powder (supplied by Mizusawa Industrial
Chemicals, Ltd.).

 The sample of zeolite powder is added to deionized water contained in a stainless steel vessel with stirring to form a slurry having a solids concentration of 40% by weight. Carbon dioxide is then blown into the zeolite slurry to form a slurry of zeolite having a pH of 11. Carboxymethylcellulose is then added to the zeolite slurry at a rate of 0.5% relative to the solids of the slurry. and suitably agitating the mixture with a strong stirrer to obtain a zeolite slurry having excellent static stability and dynamic stability.

 The properties described in Example 1 are determined on each of the suspensions obtained. The results obtained are shown in Table 9.

TABLE 9
Samples of the invention
Sample NO 9-1 9-2 9-3 9-4 9-5
Zeolite powder (1) (2) (3) (4) (5)
Viscosity (cP at 200C) 132 154 217 139 201 after preparation
Static stability 6 7 7 7 10
Dynamic stability 6 7 8 7 10
Particle size 5 2 2 2.5 0.8 primary zeolite (them)
Calcium exchange capacity (mg / g zeolite 140 120 140 150 170 anhydride)
Calcium exchange rate factor 1.1 1.7 1.6 1.5 3.0 EXAMPLE 10
In this example, the influence of the amount of organic polymer dispersant (carboxymethylcellulose) added is examined.

 To 1 kg of the suspension of zeolite H-1 neutralized with sulfuric acid prepared in Example 1, carboxymethylcellulose is added at a rate of 0.05, 0.1, 0.25, 0.5, 1 or 2% relative to the anhydrous zeolite and stirred well to obtain a suspension.

 The properties described in Example 1 are determined on each of the suspensions obtained. The results obtained are shown in Table 10.

TABLE 10
Sample of the invention Sample
comparative
Sample N @ 10-1 10-2 10-3 10-4 10-5 H-12
Quantity (%) of carboxymethyl-0.1 0.25 0.5 1 2 0.05 cellulose
Viscosity (cP at 200C) after 130 150 255 1400 3100 115 preparation
Static stability 7 8 10 10 10 6
Stability 7 9 10 10 10 2 dynamic
Primary particle size 0.8 0.8 0.8 0.8 0.8 0.8 zeolite (m)
Calcium exchange capacity (mg / g of 168 168 168 166 164 168 anhydrous zeolite)
EXAMPLE 11
Suspensions corresponding to samples 1-1, 2-1 and 7-1 and a comparative sample H-3 prepared in the preceding examples are prepared in large quantities and subjected to a real transport test according to the following procedure.

About 31 liters of suspension sample are placed in a stainless steel container having a capacity of 36 liters (having an inside diameter of about 200 mm and a height of about 1150 mm), the container is sealed and fixed directly to the tray of a truck. The truck is then driven for about 13 hours (about 500 km), the truck is stopped for about 5 hours and driven again for about 13 hours (about 500 km). Five experts then examine with the naked eye the fluidity, the viscosity and the state of precipitation of the suspension. The stability with respect to the precipitation is evaluated during the actual transfer according to the following scale.

: Stable suspension, very fluid, all the content is
flows through the discharge opening of the container.

: Light precipitate but although the precipitate has a
poor fluidity, it flows from the container.

: Light precipitate and some of the precipitate is not
Fluid: Only the supernatant flows and a precipitate that is
no fluid remains in the container.

The results obtained are shown in Table 11.

TABLEAU 1
Suspension Echantillons de l'invention de base
Echantillon N A-1 1-1 1-2 1-3
Agent neutralisant
Nature - acide acide acide sulfurique sulfurique sulfurique
Quantité (meq/100 g de zéolite anhydre - 12,8 9,0 18,6 pH de la suspension - juste après l'achèvement de l'addition de l'agent neutralisant - 11,0 11,6 10,3 - après 4 heures - 12,2 12,5 11,5
Addition de carboxyméthylcellulose - ajoutée ajoutée ajoutée
Viscosité (cP à 20 C) après préparation 94 253 219 252
Concentration en zéolite anhydre (%) 40,6 40,1 40,3 40,0
Stabilité statique 2 10 8 10
Stabilité dynamique 1 10 8 9
Taille des particules primaires de zéolite ( m) 0,8 0,8 0,8 0,8
Capacité d'échange du calcium (mg/g de zéolite anhydre) 168 168 168 166
Coefficient de vitesse d'échange du calcium (mn-1/2) 2,8 2,8 2,9 2,9 TABLEAU 1 (suite)
Echantillons comparatifs
Echantillon N H-1 H-2 H-3 H-4
Agent neutralisant
Nature acide acide acide sulfurique sulfurique sulfurique
Quantité (meq/100 g de zéolite anhydre) 12,8 5,8 20,0 pH de la suspension juste après l'achèvement de l'addition de l'agent neutralisant 11,0 12,8 9,4 après 4 heures 12,2 12,8 11,1
Addition de carboxyméthylcellulose non non non non ajoutée ajoutée ajoutée ajoutée
Viscosité (cP à 20 C) après préparation 110 185 270 152
Concentration en zéolite anhydre (%) 40,2 40,6 39,8 40,5
Stabilité statique 6 4 7 2
Stabilité dynamique 2 4 2 3
Taille des particules primaires de zéolite ( m) 0,8 0,8 0,8 0,8
Capacité d'échange du calcium (mg/g de zéolite anhydre) 168 168 163 168
Coefficient de vitesse d'échange du calcium (mn-1/2) 2,8 2,8 2,7 2,8 TABLEAU 2
Echantillons de Echantillons l'invention comparatifs
Echantillon N 2-1 2-2 2-3 H-5 H-6
Agent neutralisant nature CO2 CO2 CO2 CO2 CO2 quantité (meq/100 g de zéolite anhydre) 9,0 3,4 14,0 1,1 26,8 pH de la suspension juste après l'addition de l'agent neutra11,0 11,5 10,5 12,6 9,5 lisant après 4 heures 12,1 12,4 11,6 12,9 10,1
Viscosité (cP, 20 C) après la préparation 214 222 220 205 216
Concentration (%) en zéolite anhydre 40,7 40,7 40,6 40,6 40,7
Stabilité statique 10 9 10 3 6
Stabilité dynamique 10 10 9 5 3
Taille des particules primaires de zéolite ( m) 0,8 0,8 0,8 0,8 0,8
Capacité d'échange des ions calcium (mg/g de 168 168 168 168 160 zéolite anhydre)
Coefficient de vitesse d'échange des ions calcium (mn-1/2) 2,9 2,8 2,9 2,7 2,6 TABLEAU 3
Echantillons de l'invention
Echantillon N 3-1 3-2 3-3 3-4 3-5 3-6 3-7
Agent neutralisant nature HNO3 à HCl à acide acide acide HCl + CO2 + 20% 20 % acétique citrique oxalique acide
HNO3 à 10 % à 10 % à 10% oxalique quantité (meq/100 g de zéolite 13,3 13,0 14,4 14,7 14,5 13,7 11,9 anhydre) pH de la suspension juste après l'addition de l'agent 10,9 11,0 11,2 11,1 11,0 11,1 neutralisant après 4 heures 12,0 12,1 12,1 12,1 12,2 12,0 11,7
Viscosité (cP à 20 C) après préparation 243 236 204 194 181 199 213
Concentration (%) en zéolite anhydre 40,2 40,3 40,5 40,5 39,8 40,0 40,4
Stabilité statique 9 9 9 9 9 9 10
Stabilité dynamique 9 9 9 9 7 8 9
Taille des particules primaires de 0,8 0,8 0,8 0,8 0,8 0,8 0,8 zéolite ( m)
Capacité d'échange des ions calcium 168 168 168 168 167 167 168 (mg/g de zéolite anhydre) TABLEAU 4
Echantillon de Echantillons l'invention comparatifs
Echantillon N 4-1 H-7 H-8
Agent neutralisant nature hydrogénocarbonate de carbonate carbonate sodium de sodium de sodium quantité (meq/100 g de zéolite anhydre) 12,5 12,5 25,0 pH de la suspension juste après l'addition de l'agent neutralisant 11,0 13,1 13,1 après 4 heures 11,9 13,1 13,1
Viscosité (cP à 20 C) après préparation 299 1270 12640
Concentration (%) en zéolite anhydre 40,0 40,1 40,0
Stabilité statique 9 7 10
Stabilité dynamique 8 3 7
Taille des particules primaires de zéolite ( m) 0,8 0,8 0,8
Capacité d'échange des ions calcium (mg/g de zéolite 170 170 170 anhydre) TABLEAU 5
Echantillons de l'invention
Echantillon N 5-1 5-2 5-3
Dispersant polymère carboxy- alginate alcool méthyl/ de sodium polyvinylique amidon
Viscosité (cP à 20 C) après la préparation 778 990 415
Concentration (%) en zéolite anhydre 40,5 40,6 40,6
Stabilité statique 8 8 7
Stabilité dynamique 7 8 6
Taille des particules primaires de zéolite ( m) 0,8 0,8 0,8
Capacité d'échange des ions calcium (mg/g de 168 167 167 zéolite anhydre) TABLE 11
Sample Samples the Comparative Invention
Sample NO
Stability with respect to precipitation during actual transport

TABLE 1
Suspension Samples of the basic invention
Sample N A-1 1-1 1-2 1-3
Neutralizing agent
Nature - sulfuric acid sulfuric acid sulfuric acid
Amount (meq / 100 g anhydrous zeolite - 12.8 9.0 18.6 pH of the suspension - just after the completion of the addition of the neutralizing agent - 11.0 11.6 10.3 - after 4 hours - 12.2 12.5 11.5
Addition of carboxymethylcellulose - added added added
Viscosity (cP at 20 ° C.) after preparation 94 253 219 252
Concentration of anhydrous zeolite (%) 40.6 40.1 40.3 40.0
Static stability 2 10 8 10
Dynamic stability 1 10 8 9
Primary particle size of zeolite (m) 0.8 0.8 0.8 0.8
Calcium exchange capacity (mg / g anhydrous zeolite) 168 168 168 166
Coefficient of calcium exchange rate (min-1/2) 2.8 2.8 2.9 2.9 TABLE 1 (continued)
Comparative samples
Sample N H-1 H-2 H-3 H-4
Neutralizing agent
Nature acid sulfuric acid sulfuric sulfuric acid
Amount (meq / 100 g anhydrous zeolite) 12.8 5.8 20.0 pH of the suspension just after the completion of the addition of the neutralizing agent 11.0 12.8 9.4 after 4 hours 12 , 2 12.8 11.1
Addition of carboxymethylcellulose no no no no added added added added
Viscosity (cP at 20 C) after preparation 110 185 270 152
Anhydrous zeolite concentration (%) 40.2 40.6 39.8 40.5
Static stability 6 4 7 2
Dynamic stability 2 4 2 3
Primary particle size of zeolite (m) 0.8 0.8 0.8 0.8
Calcium exchange capacity (mg / g anhydrous zeolite) 168 168 163 168
Coefficient of calcium exchange rate (min-1/2) 2.8 2.8 2.7 2.8 TABLE 2
Sample Samples Comparative Invention
Sample N 2-1 2-2 2-3 H-5 H-6
Neutralizing agent nature CO2 CO2 CO2 CO2 CO2 quantity (meq / 100 g anhydrous zeolite) 9.0 3.4 14.0 1.1 26.8 pH of the suspension just after the addition of the neutra11.0 agent 11 , 5 10.5 12.6 9.5 reading after 4 hours 12.1 12.4 11.6 12.9 10.1
Viscosity (cP, 20 C) after preparation 214 222 220 205 216
Concentration (%) of anhydrous zeolite 40.7 40.7 40.6 40.6 40.7
Static stability 10 9 10 3 6
Dynamic Stability 10 10 9 5 3
Primary particle size of zeolite (m) 0.8 0.8 0.8 0.8 0.8
Calcium ion exchange capacity (mg / g of 168 168 168 168 160 anhydrous zeolite)
Coefficient of calcium ion exchange rate (min-1/2) 2.9 2.8 2.9 2.7 2.6 TABLE 3
Samples of the invention
Sample N 3-1 3-2 3-3 3-4 3-5 3-6 3-7
Natural neutralizing agent HNO3 to HCl with acidic acid HCl + CO2 + 20% 20% acetic acidic citric acid
HNO3 10% to 10% to 10% oxalic quantity (meq / 100 g zeolite 13.3 13.0 14.4 14.7 14.5 13.7 11.9 anhydrous) pH of the suspension just after the addition of agent 10.9 11.0 11.2 11.1 11.0 11.1 neutralizer after 4 hours 12.0 12.1 12.1 12.1 12.2 12.0 11.7
Viscosity (cP at 20 C) after preparation 243 236 204 194 181 199 213
Concentration (%) of anhydrous zeolite 40.2 40.3 40.5 40.5 39.8 40.0 40.4
Static stability 9 9 9 9 9 9 10
Dynamic Stability 9 9 9 9 7 8 9
Primary particle size 0.8 0.8 0.8 0.8 0.8 0.8 0.8 Zeolite (m)
Calcium ion exchange capacity 168 168 168 168 167 167 168 (mg / g anhydrous zeolite) TABLE 4
Sample of the samples the comparative invention
Sample N 4-1 H-7 H-8
Neutralizing agent nature sodium carbonate sodium carbonate sodium carbonate carbonate quantity (meq / 100 g anhydrous zeolite) 12.5 12.5 25.0 pH of the suspension just after the addition of the neutralizing agent 11.0 13, 1 13.1 after 4 hours 11.9 13.1 13.1
Viscosity (cP at 20 ° C) after preparation 299 1270 12640
Concentration (%) of anhydrous zeolite 40.0 40.1 40.0
Static stability 9 7 10
Dynamic Stability 8 3 7
Primary zeolite particle size (m) 0.8 0.8 0.8
Calcium ion exchange capacity (mg / g zeolite 170 170 170 anhydrous) TABLE 5
Samples of the invention
Sample N 5-1 5-2 5-3
Dispersant polymer carboxy-alginate methyl alcohol / sodium polyvinyl starch
Viscosity (cP at 20 ° C) after preparation 778 990 415
Concentration (%) of anhydrous zeolite 40.5 40.6 40.6
Static stability 8 8 7
Dynamic Stability 7 8 6
Primary zeolite particle size (m) 0.8 0.8 0.8
Calcium ion exchange capacity (mg / g of 168 167 167 anhydrous zeolite)

Claims (12)

claims  1. A process for preparing a zeolite suspension having excellent static stability and dynamic stability and good fluidity, characterized in that an aqueous cake or an aqueous suspension containing water and a zeolite in a form is neutralized. such that they are substantially inseparable from one another by filtration, with an inorganic or organic acid or an anhydride or corresponding acidic salt so that the pH of the zeolite suspension upon completion of the addition of said acid , acid anhydride or acidic salt is in the range of 9.5 to 12 and the pH of the zeolite suspension at rest after the addition of said acid, acid anhydride or acidic salt is in the range of 11 3 to 12.7, a water-soluble or water-dispersible organic polymer dispersant of at least 0.1% by weight, based on the anhydrous zeolite, is added to the neutralized zeolite suspension, and submits the obtained suspension to a stir with a strong shear.  The process according to claim 1, wherein said aqueous cake or said starting aqueous slurry has a concentration such that the concentration of anhydrous zeolites of the final slurry is from 30 to 50% by weight.  The process of claim 1, wherein said aqueous cake or aqueous starter slurry contains 0.1 to 1.0 wt.% Of a free alkali metal component.  4. The process of claim 1, wherein the zeolite has a CaO binding capacity of 120 to 180 mg / g.  5. The process of claim 1, wherein the zeolite is a type A zeolite.  6. The process of claim wherein the zeolite has a primary particle size of less than 1 μm.  The process of claim 1, wherein the zeolite is neutralized with carbon dioxide.  8. A process according to claim 1, wherein the acid, acid anhydride or acid salt is added to the suspension in an amount of 7 to 45 milliequivalents per 100 g of the anhydrous zeolite.  The process of claim 1 wherein the water soluble or water dispersible organic polymeric dispersant is a dispersant containing carboxy and hydroxy radicals.  The process of claim 9 wherein the dispersant is carboxymethylcellulose.  11. Zeolite suspension having excellent stability and fluidity, characterized in that it comprises an aqueous suspension containing 3 to 50% by weight of zeolite, in anhydrous zeolite relative to the total suspension, an alkali metal salt. an inorganic or organic acid in an amount of 7 to 45 milliequivalents per 100 g of the anhydrous zeolite, and an organic polymer dispersant soluble in water or dispersible in water at a rate of at least 0.1% by weight with respect to the anhydrous zeolite, said aqueous suspension having a pH of 12.7 to 11.3 and a viscosity of 50 to 5000 cP measured at 200C.  The zeolite slurry of claim 11, wherein said inorganic or organic acid alkali metal salt is formed in situ by neutralization of a slurry of zeolite with a mineral acid, an organic acid or an acid anhydride. or corresponding acid salt.