RU2335533C1 - Method of production of granulated synthetic zeolite-containing component of synthetic detergents - Google Patents

Abstract

FIELD: technological processes; chemistry.

SUBSTANCE: fine-grained zeolite of A-LSX type with crystal size of 0.9-3.0 micrometer is mixed with carboxymethyl cellulose (CMC), taken in the amount of 3-15 wt % in conversion to dry zeolite. Mixture is extruded. Granules are dried at 130-180°C, crushed and fractionated for production of end product with particle size of 0.2-2.5 micrometer. Fraction of particle with size below 0.2 mm are returned to mixing with CMC.

EFFECT: increase of cation-exchange efficiency.

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Description

The invention relates to a technology for producing granular zeolite components of synthetic detergents (CMC) and may find application in the production of CMC in the chemical industry.

Synthetic zeolites, which are used as ion exchangers that replace, partially or completely, phosphates in synthetic detergents, are widely used in the production of CMC.

Zeolites, both natural and artificial, are aluminosilicates of a porous crystalline structure formed from a three-dimensional framework of TO ₄ tetrahedra, where T can be silicon or aluminum. The presence of aluminum in tetrahedral coordination in the crystal lattice determines an excess negative charge balanced by alkali metal ions (Na, K, Rb, Li or Cs), alkaline earth metal ions (Mg or Ca) or ammonium ions.

It is known to use zeolite A as an additive in washing systems to improve their cleaning effect (US Patent No. 4,649,036). Zeolite is used to remove polyvalent metal ions from washing water, in particular calcium ions, which determine the hardness of water to the greatest extent. However, type A zeolite does not appreciably reduce the stiffness caused by the presence of a magnesium ion, because it has insufficient pore size relative to the radius of this ion in an aqueous solution at an initial contact temperature during washing with tap water.

At room temperature, before the entry of a washing solution containing, for example, surfactants, bleaching agents, carbonates, etc., the kinetics of magnesium ion exchange is very slow. Therefore, the ability of type A zeolite to remove magnesium ions is insufficient in practice so much that auxiliary additives are needed.

To improve the action of the washing system and to prevent the formation of residual plaque on the fabric, it is necessary, almost completely, to remove calcium and magnesium ions from the washing system, and as quickly as possible. If these ions are not removed, then the soluble salts of calcium and magnesium present in the water will increase (due to the presence of other components of the detergent composition — sodium carbonate) the formation of precipitation of mixed calcium and magnesium carbonates and carbonate hydrates.

In addition, the formation of poorly soluble salts of these ions, especially in detergent compositions containing anionic surfactants, reduces the active amount of these components necessary for the washing itself. To this should be added the fact that these salts are deposited on the tissues and this leads to possible damage to their fibers.

Another known zeolite with a washing ability is, for example, described in German patent DD 43221, type X zeolite, which has pore openings large enough to provide a high rate of ion exchange, in particular magnesium ions. However, the Si / Al ratio, which, in contrast to this ratio in type A zeolite, always significantly exceeds 1, leads to a decrease in the overall ion exchange capacity. In addition, all centers (a uniform porous system with an average pore diameter of 4.2 Å) are accessible for ion exchange in type A zeolite. The type X zeolite lattice contains cavities less accessible for ion exchange (non-uniform porous system: cavities with pores with an average diameter of 7.4 Å and cavities with pores with an average diameter of 2.2 Å).

This situation led to the creation of a zeolite with a Si / Al ratio between 0.9 and 1.1, similar to that in type A zeolite. The zeolite has been identified as type LSX zeolite (Low Silica X - type X low silicon zeolite), which has advantages ion-exchange ability close to the ability of type A zeolite due to the Si / Al ratio. At the same time, the ion exchange rate due to its structure is typical of type X zeolite. LSX type zeolite is described, for example, in GB 1,580,928.

However, known methods for producing LSX type zeolite are extremely expensive for economically acceptable and commercially viable industrial production. Its preparation requires an excessively long production time and, in particular, an aging time of 15 to 100 hours at a temperature below 50 ° C. In addition, the need for synthesis at a high ratio of K ₂ O / (K ₂ O + Na ₂ O) from 0.10 to 0.40 introduces an additional negative point that in the case of the presence of potassium in the final zeolite, the latter requires purification to achieve the required ion-exchange ability and exchange rate and characteristics necessary for a product suitable for use in the field of detergents.

A simpler and less expensive method for producing a new microporous crystalline material, hereinafter referred to as A-LSX type zeolite, has been developed (Patent RU No. 2148014). This zeolite has a structure that represents the advantages of both type A zeolites and type X zeolites. In addition, this zeolite is particularly suitable for use in the detergent industry in that it provides high ability and speed of removal of calcium and magnesium ions present in the water normal flushing temperature.

It should be noted that the A-LSX type zeolite provides the ion-exchange ability and the exchange rate of calcium and magnesium is much higher than those obtained by simple physical mixing of type A and X zeolites. In addition, in the type A-LSX zeolite, the percentage of LSX type zeolite is 20-30 wt.%, which is sufficient to achieve the desired goals in terms of exchange ability and exchange rate of calcium and magnesium ions. However, if necessary, the percentage of LSX type zeolite can reach 90% by weight.

A disadvantage of the A-LSX type zeolite is that the zeolite has an average particle diameter of from 0.9 to 10 μm, including extreme values, preferably from 1.5 μm to 5 μm, including extreme values. The introduction of zeolites in the composition of CMC is associated with certain difficulties, since zeolites are a highly dusting powder with a particle size of 1.5-5.0 microns, which complicates the technology, worsens working conditions and reduces the quality of the final product. According to GOST 25644-83, CMC granules with a size in the range of 0.2-2.5 mm are standard in the production of synthetic detergents.

The use of powdered zeolite, thus, completely eliminates the possibility of preparing CMC by dry mixing the raw materials included in the detergent receptor.

A known method of producing granular free-flowing components of CMC with a high bulk density containing 15-20 wt.% Ethoxylated with ethylene oxide alcohols C ₁₂ -C ₂₄ or other non-ionic hydroxyalkylated surfactants, 5 wt.% Anionic surfactants, 40-80 wt.% Inorganic fillers ( sodium tripolyphosphate, type A zeolite, sodium metasilicate, soda, sodium sulfate), 0.5-10 wt.% polyphosphonic acids, polycarboxylic acids, sodium toluenesulfonate, CMC, optical brightener and 10-20 wt.% adsorption or crystallization water (application of Germany No. 3434864, M. cl. С01D 11/02 , 1986).

The disadvantages of this method are:

1. The content of environmentally harmful phosphorus compounds, which, falling into natural bodies of water, cause their poisoning (eutrophication).

2. The use in the composition of the composition of many types of raw materials, which significantly complicates the process of production of granular product.

A known method of producing granular zeolite - component CMC containing carbonates and zeolites, which provides:

- preparation of zeolites of types A or X in the form of powders by hydrothermal crystallization of mixtures of sodium silicate and aluminate, separation of the mother liquor, washing and drying of the zeolite (average particle size of the zeolite is less than 15 μm);

- preparation of a suspension consisting of 20-60 wt.% zeolite, 5-30 wt.% soda (sodium carbonate), 5-15 wt.% sodium silicate and 25-60 wt.% water;

- spray drying the resulting mixture with the formation of spherical granules with a moisture content of 2-16 wt.% and cation exchange capacity (CBS) for CaO 170-190 mg / g of product;

- mixing the obtained granules with a nonionic surfactant (US Patent No. 4,406,808, CL 252-91, 1983).

This method has the following disadvantages.

1. The ability to obtain granular zeolite for CMC by spray drying an aqueous suspension of raw materials only in the form of microspherical granules 60-200 microns in size, which makes it impossible to use such a product in the preparation of CMC by dry mixing.

2. The use, as a raw material for the preparation of granules, of coarse type X zeolite, which obviously has 30-40 wt.% Lower KOS in CaO than type A zeolite, and lower KOS in MgO, due to the presence of zeolite particles of size up to 15 microns.

3. The use of zeolites (raw materials) with a particle size of up to 15 microns, because the smaller this size, the higher the KOS of the zeolite, both in CaO and MgO, and therefore, it is desirable to use powdered zeolite with a crystal size of not more than 4 microns.

A known method of producing a granular zeolite filler for synthetic detergents (RF patent No.2016846, C01B 33/34, 1994), which involves mixing solutions of silicate and sodium aluminate at a molar ratio of SiO ₂ / A ₂ O ₃ equal to 2.0-2, 5; crystallization of the resulting silica-aluminum hydrogel into type A zeolite at a temperature of 60-100 ° C for 0.4-6.0 hours and spray drying of a suspension of zeolite in the mother liquor with a concentration of: 100-250 g / l zeolite, 55-110 g / l NaOH , 5-30 g / l SiO ₂ in the flue gas stream containing CO ₂ . In this case, complete or partial neutralization of sodium hydroxide occurs, leading to the formation of a granular zeolite filler for CMC, containing: 50-60 wt.% Type A zeolite, 25-30 wt.% Soda, 2-8 wt.% Sodium silicate, 2- 5 wt.% Sodium hydroxide and 2-15 wt.% Water. The product has a CBS of CaO of 190-200 mg / g and a fractional composition of 80-200 microns.

One of the disadvantages of this method is the ability to obtain a zeolite-containing component of CMC only in the form of microspherical granules (60-200 μm), which makes it impossible to use them in the production of CMC by dry mixing. Another is low CBS for MgO, as Type A zeolite (NaA) has high ion-exchange properties when exchanging Na ⁺ cations for Ca ²⁺ and low in exchanging Na ⁺ for Mg ²⁺ .

A known method of producing granular synthetic zeolite used in CMC formulations (A.C. USSR No. 1159885, C01B 33/28, 1985). The method involves spraying using a pneumatic nozzle of a liquid medium onto a powdered zeolite while mixing it in a device with a vibro-boiling layer. As a liquid medium, an aqueous suspension of zeolite with a binder is used with a ratio of solid and liquid phases equal to (0.2-1.0): 1. As a binder use aqueous solutions of surface-active substances (surfactants). A granular zeolite with a binder with a particle size of 0.2-2.5 mm is obtained.

The known method has the following disadvantages.

1. The complexity and multi-stage technology for producing granules associated with the need to prepare and use only aqueous suspensions of zeolite and surfactants as a binder.

2. High energy consumption, because spraying occurs at a ratio of (0.2-1.0): 1 between the solid and liquid phases.

3. The inability to obtain granules containing less than 15 wt.% Water (humidity), because the method does not provide for the drying of granules at a temperature above 100 ° C. As a result, the finished product crumbles and loses flowability during storage and transportation, which makes it impossible to use it in the dry mix CMC production and significantly complicates its use in the tower production of CMC (through repulpation and subsequent spray drying).

The well-known "Method for the production of granular synthetic zeolite" (AS USSR No. 1156726, BJ 2/20, 2/28; CB 33/28, 1985).

According to this method, a zeolite with a moisture content of 20-40 wt.% Is mixed with a binder - powdered carboxymethyl cellulose (CMC), taken in an amount of 0.5-5.0 wt.% Calculated on dry zeolite and having a particle size of not more than 1.5 mm The mixture is extruded through a screw granulator grate, and the obtained granules with a diameter of 4.5 mm and a length of 6-9 mm are dried in a fluidized bed apparatus at 80 ° C and a fluidization number of 0.8-1.2. Get granular zeolite with a binder with a residual moisture content of 5 wt.% And mechanical strength of 7-10 kgf / cm ² (0,07-0,1 kgf / mm ² ).

This method has the following disadvantages.

1. The use of a binder in an amount of 0.5-5.0 wt.% Based on dry zeolite does not provide zeolite granules with a binder of the necessary mechanical strength. Granules are destroyed to a fraction of less than 0.2 mm during storage and transportation.

2. The use of a binder in an amount of 0.5-5 wt.%, Calculated on dry zeolite, does not allow us to speak of a granular product as a complex compound including zeolite and CMC (surfactant) in the ratio required for the production of CMC . In the CMC formulations, the zeolite is 10-15 wt.%, And the desired CMC content is about 1 wt.%. If you introduce granular zeolite obtained by a known method in the composition of CMC in the amount of 10-15 wt.%, The content of CMC will be only 0.05 ÷ 0.5-0.075 ÷ 0.75. Thus, CMC must be introduced as a separate type of raw material directly into the CMC.

3. Zeolite granules with a binder diameter of 4.5 mm and a length of 6–9 mm cannot be used to obtain CMC by dry mixing, as well as dust (fraction <0.2 mm) formed during storage and transportation. As already noted, a particle size of granular zeolite of 0.2-2.5 mm is required.

4. The use of only powdered CMC is provided as a binder, which complicates the process of mixing with zeolite and leads to inhomogeneity of granules and, as a result, can lead, with such a small amount of binder, to 0.5-5.0 wt.%, To their mechanical destruction .

5. Drying in the apparatus of a fluidized bed of extruded granules leads to the formation of microcracks on the granules and a decrease in their mechanical strength.

6. The use of zeolite type A, as well as the use of coarse zeolite type X, leads to the production of a granular component CMC having a low KOS in MgO.

The closest in technical essence and the achieved result to the proposed invention is the "Method for producing granular synthetic zeolite-containing component CMC" (Patent RU No. 2230778, C11D 3/02, C01B 39/22, 2004), which was chosen as the prototype.

According to the known method, highly dispersed zeolite type X (predominant crystal size of 1-3 μm) is mixed with carboxymethyl cellulose (CMC), taken in an amount of 5-10 wt.%, Counting on dry zeolite. Moreover, CMC is used in the form of a dry powder or in the form of an aqueous solution. The mixture is extruded. Cutting granules are dried in a belt dryer at a temperature of 130-180 ° C. Then the granules are crushed and the resulting crumb is classified to obtain a commercial fraction of 0.2-2.5 mm in size. The smaller fraction resulting from crushing is again sent to mixing with the binder.

The known method has disadvantages.

1. Low cation exchange ability (CBS) of the CMC component for Ca ²⁺ cations (CBS for CaO).

2. Insufficiently high cation exchange capacity (CBS) of the CMC component for Mg ²⁺ cations (CBS for MgO). Not quite the optimal composition of the CMC component, which would meet the requirements for the composition of modern CMC.

The objective of the invention is to develop a method for producing a granular synthetic zeolite-containing component CMC with improved quality indicators in terms of high CBS CaO and MgO, which has a balanced complex composition (zeolite + surfactant), i.e. such a component of CMC, which can be used in the production of modern detergents by dry mixing of raw materials.

A comparative analysis of the proposed method with the prototype allows us to conclude that the claimed method differs from the known mixture of finely dispersed (preferred crystal size 0.9-3.0 μm) zeolite, namely type A-LSX, with carboxymethyl cellulose taken in an amount of 3-15 wt.%, counting on dry zeolite. Moreover, CMC is used in the form of a dry powder or in the form of an aqueous solution, as in the prototype.

An analysis of known methods for producing synthetic zeolites and granular zeolite-containing components of CMC showed that the preparation of highly dispersed zeolite type X, mixing zeolite with CMC, extruding the mixture to obtain cuttings and then drying them is known. There is also known a method for producing and using in powder CMC a zeolite powder of type A-LSX. However, only the fact of mixing finely dispersed (predominantly crystal size 0.9-3.0 μm) zeolite, namely A-LSX type, with CMC taken in an amount of 3-15 wt.%, Counting on dry zeolite, allows drying after drying at a temperature 130-180 ° C to obtain mechanically strong granules of the synthetic component CMC. Moreover, such a component of CMC, which has a balanced (optimal) chemical (zeolite / surfactant ratio) composition for use in modern detergent formulations and high CBS for MgO and CaO.

Previously known technological operations: the use of a binder in the form of an aqueous solution of CMC, extruding the mixture, crushing and subsequent classification of granules lead to the desired particle size (0.2-2.5 mm) necessary to ensure the possibility of using the CMC component in the production of detergents dry mixing of raw materials. The use of a fraction of less than 0.2 mm formed during crushing, again upon receipt of the CMC component, allowed us to create a closed, waste-free, environmentally friendly production scheme.

The essence of the invention is as follows.

A finely dispersed (predominantly crystal size of 0.9-3.0 μm) type A-LSX zeolite (humidity 20-40 wt.%) Is mixed with CMC taken in the form of a dry powder (particle size ≤1.5 mm) or an aqueous solution, in an amount of 3-15 wt.% by weight of dry zeolite. Mixing is carried out until a homogeneous paste is formed. The paste is extruded through a screw granulator die. The resulting extrudates - cuttings with a diameter of 4 mm and a length of 5-8 mm, are dried in a belt dryer at a temperature of 130-180 ° C in a steam-air medium. Get mechanically strong 0.4-1.0 kg / mm ² (40-100 kg / cm ² ) granules containing 85-97 / 15-3 wt.% Zeolite type A-LSX and CMC, in terms of dry matter, respectively. Granules are crushed to obtain a fraction of 0.2-2.5 mm and classified by screening. A fraction of less than 0.2 mm is again sent to mixing with a binder. Commodity granular synthetic zeolite-containing component CMC has high BOC for MgO and CaO, flowability, does not dust, does not deteriorate during transportation and storage and is used in the production of CMC by dry mixing.

Example

100 g of highly dispersed zeolite A-LSX with a moisture content of 20 wt.% Are mixed with 8.9 g of CMC (added as a solution). Mixing is carried out until a homogeneous paste. The paste is extruded through a screw granulator die. The resulting cuttings are dried at 130 ° C in a vapor-air environment. Get mechanically strong 0.8 kg / mm ² (80 kg / cm ² ) granules containing 90 wt.% Zeolite type A-LSX and 10 wt.% CMC, calculated on the dry matter. Granules are crushed to obtain a fraction of 0.2-2.5 mm and classified by screening. A fraction of less than 0.2 mm is re-sent to mix with a binder.

The resulting sample is analyzed.

Calcium ion exchange is carried out using a device with an electrode for a specific ion in a standard system. The exchange ability of the sample for calcium ion is measured. For this purpose, 1 liter of an aqueous solution containing calcium chloride in an amount of 3.135 mmol of calcium, and 20 cm ^{3 of a} buffer solution with a pH of 10.2 are mixed and kept at a constant temperature of 22 ° C. After immersing the previously stabilized and calibrated specifically on the calcium electrode, a zeolite sample corresponding to 1 g of anhydrous product is introduced. After 15 minutes, the amount of calcium ions in the solution is measured.

Magnesium ion exchange is carried out on a similar device, modified by the use of an electrode specifically designed for magnesium ions. For this purpose, 1 liter of an aqueous solution containing magnesium chloride in an amount of 3.135 mmol of magnesium, and 20 cm ^{3 of a} buffer solution with a pH of 10.2 are mixed and kept at a constant temperature of 22 ° C. After immersing the previously stabilized and calibrated specifically on the magnesium electrode, a zeolite sample corresponding to 1 g of anhydrous product is introduced. After 15 minutes, the amount of magnesium ions in the solution is measured.

The properties of the CMC component and the data of the remaining examples are presented in the table.

Using in the preparation of the CMC component according to the proposed method, A-LSX zeolite with a crystal size of more than 3.0 μm leads to a deterioration in the cation exchange capacity (CBS) for CaO and MgO of a commercial product (example 6 is comparative).

Composition and properties of granular synthetic zeolite component CMC Examples The composition of the component CMC, zeolite / CMC, wt.% CBS MgO, mg / g CBS CaO, mg / g Strength, kg / mm ² Return fraction <0.2 mm, wt.% Prototype X / CMC = 90-95 / 10-5 70-73 75-80 0.6-0.8 15-30 one A-LSX / CMC = 90/10 136 172 0.8 fifteen 2 A-LSX / CMC = 85/15 115 154 1,0 10 3 A-LSX / CMC = 97/3 150 200 0.4 35 four A-LSX / CMC = 99/1 (comparative) 155 210 0.2 45 5 A-LSX / CMC = 80/20 (comparative) 102 136 1,2 7 6 A-LSX / CMC = 90/10 zeolite with a size of 5.0 microns (comparative) 130 162 0.8 fifteen

Claims (1)

A method for producing a granulated synthetic zeolite-containing component CMC, including mixing zeolite with a binder - carboxymethyl cellulose (CMC), extruding the mixture, drying the granules at a temperature of 130-180 ° C, crushing them, fractionating to obtain commodity chips with a size of 0.2-2.5 mm and the return of the crumbs fraction of less than 0.2 mm for mixing with a binder, characterized in that a highly dispersed zeolite type A-LSX with a crystal size of 0.9-3.0 μm and CMC are used in the amount of 3-15 wt.% in terms of on dry zeolite.