RU2615506C1 - Method for granulation of zeolite as synthetic detergent component - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: zeolite granulating method is described, including zeolite powder is moistening with granulation liquid, an aqueous solution of SokalanCP5 acrylic maleic acid copolymer®, manufactured by BASF, Germany, with a molecular weight of at least 70,000 g/mol is taken as the granulation liquid component, the humidified mixture is stirred until a homogeneous plastic mass is obtained, granules are formed and dried; according to the invention, 33.3-50.0% aqueous solution of acrylic maleic acid copolymer is taken as the granulation liquid, during preparation, the mass ratio of solid zeolite phase and granulation liquid is 5:1, zeolite granulation is performed using a sieve with mesh size of 200 microns, after drying and granulating, zeolite is passed through the sieve with mesh size of 200 microns.

EFFECT: obtaining of granular zeolite with good performance, the preparation of granules with sufficient mechanical strength that do not disintegrate during transportation and have good solubility with the ability to form a stable zeolite suspension with uniform zeolite distribution over the entire solution volume, reduced residual moisture content of zeolite after granules formation.

2 cl, 2 tbl, 9 ex

Description

The invention relates to methods for producing granular zeolite used in the chemical industry as a component in the production of synthetic detergents (CMC).

Zeolites in most cases are obtained in the form of powders that are practically not subjected to the molding process. The use of powdered zeolite as a component of detergents causes difficulties in transporting and adding powder to detergents, creating a very dusty room, sticking in the pneumatic transport system and clogging of the equipment that dispenses zeolite in detergents. In order to be able to be used as an additive to CMC, zeolites are molded in the form of granules with a size of 200-2500 microns, while the molding method and the type of binder used should provide:

- sufficient mechanical strength of the granules - they should not crumble under slight external loads during transportation or dosing in the production of CMC;

- solubility of the granules - when added to the liquid components of the CMC, the granules should be “dispersed” rather quickly, within 1-2 minutes, forming a stable suspension without the formation of a significant precipitate due to sedimentation of zeolite particles;

- significant sorption capacity for calcium - the ability to remove calcium cations (magnesium) from aqueous solutions with the highest rate.

A method for producing zeolite components of synthetic detergents [RU 2230779 C1, 11.27.2002], in which concentrated solutions of silicate and sodium aluminate are mixed at a molar ratio of silica to alumina in a mixture of 2.0-2.5, is described. The mixture is crystallized at a temperature of 60-80 ° C and stirred for 0.4-6.0 hours, after which part of the mother liquor is separated. The zeolite suspension in the remaining mother liquor is diluted with water to the previous concentration and sent to spray drying in a flue gas stream. The disadvantage of this method is the need to use silica-aluminum hydrogel, which necessitates the preparation of working solutions of sodium silicate and aluminate, as well as a method of forming spray drying, which makes the process more expensive. In addition, using this method it is possible to obtain granular zeolite for CMC only in the form of microspherical granules of 60-200 μm in size, which makes it impossible to use such a product in the preparation of CMC by dry mixing.

A known method of producing granular zeolite filler for synthetic detergents [SU 1731799 A1, 05/07/1992], the essence of the method is to mix (based on dry matter) sodium carbonate (11-30 wt.%), Sodium silicate 5-10% of the mass ., sodium sulfate (5-10% wt.) and zeolite A (up to 100% wt.), get a suspension in finished form containing 25-40% of the mass. dry matter. This ensures uniform distribution of the components in the mixture and complete homogenization of the suspension. Zeolite is used in the form of a powder, wet cake or suspension. The prepared suspension is subjected to spray drying and get granules with a size of 50-200 microns with a strength of 48-62%. The disadvantage of this method is the use of a significant amount of reagents, as well as the molding method - spray drying.

A known method of molding zeolite (RF №2016846, 07/30/1994), the essence of which is as follows.

Mix solutions of silicate and sodium aluminate at a molar ratio of SiO ₂ : Al ₂ O ₃ = 2.0-2.5. The resulting silica-aluminum hydrogel is crystallized in type A zeolite at 60-100 ° C for 0.4-6.0 hours. A mixture of a suspension of type A zeolite with a concentration of 100-250 g / l, sodium hydroxide solution with a concentration of 55-110 g / l and liquid glass solution with concentration (on silicon dioxide) of 5-30 g / l, which is sent to spray drying in a stream of flue gases containing carbon dioxide. In this case, complete or partial carbonization of sodium hydroxide occurs, leading to the formation of a granular zeolite filler for CMC, containing: 50-60% of the mass. zeolite type A, 25-30% of the mass. soda, 2-8% of the mass. sodium silicate, 2-5% of the mass. sodium hydroxide and 2-15% of the mass. water. The disadvantage of this method is the use of a significant amount of reagents, as well as the molding method - spray drying.

A method is proposed for molding zeolite for use as a component of CMC (RF No. 2335533, 10/10/2008), in which highly dispersed (mainly crystal size 0.9–3.0 μm) type A-LSX zeolite (humidity 20–40 wt.%) Is mixed with carboxymethyl cellulose ( CMC) as a binder, taken in the form of a dry powder (particles ≤1.5 mm in size) or an aqueous solution, in an amount of 3-15 mass. % by weight of dry zeolite. Mixing is carried out until a homogeneous paste is formed, after which the paste is extruded through a die of a screw granulator. 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 mass. % zeolite type A-LSX and CMC, calculated on the 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 a flowability, does not dust, does not deteriorate during transportation and storage. The disadvantage of this method is that the resulting product can only be used in the production of CMC by dry mixing, as it has insufficient solubility.

The closest analogue in accordance with the same purpose and the number of matching features is the method described in the patent (US 5399287 A, 03/21/1995). The zeolite powder is introduced into the mixer / granulator and sprayed with a granulation liquid until a homogeneous mixture is obtained. Granulation liquid consists (based on the calculation of 49.5% of the mass. Per 100% of the mass. Anhydrous zeolite) of: 20% of the mass. 40% solution of the copolymer brand Sokalan®CP5 (company BASF), 14% of the mass. saturated alcohols of composition C ₁₂ -C ₁₈ , 66% of the mass. water with a mass ratio of solid phase: liquid of approximately 2: 1.

After mixing for 10-60 seconds, the granulation liquid is sprayed through the nozzle for 1-5 minutes and the mixture is granulated for another 1-3 minutes with continuous stirring. The granules leaving the mixer are dried with hot flue gases (temperature - 70 ° C) in a fluidized bed.

The disadvantages of this method are the significant expenditure rates of the reagents when obtaining the final product, which leads to its cost increase, the complexity of the granulation method. In addition, with the indicated ratio of solid phase: granulation solution of approximately 2: 1, the residual humidity will be significant, which will require an increase in the drying time of the zeolite after granulation.

The objective of the present invention is to reduce the cost of granular zeolite used as a component in the production of synthetic detergents, simplifying the granulation method, which allows to obtain granular zeolite with good performance (solubility, sorption capacity for calcium) is not worse than the prototype, reducing the drying time of zeolite after granulation .

The technical result is the possibility of simple molding of a powdery zeolite with granule size adjustment by changing the size of the mesh of the cleaning sieves, to obtain granules with sufficient mechanical strength, not crumbling during transportation and having good solubility, with the possibility of forming a stable suspension with a uniform distribution of zeolite throughout the volume of the solution, a decrease in the residual moisture of the zeolite after molding its granules.

The problem is solved and the technical result is implemented in a method for producing granular zeolite, which consists in the following:

- powdered zeolite is moistened with granulation liquid;

- as an component of the granulation liquid, an aqueous solution of a Sokalan®CP5 acrylo-maleic acid copolymer made by BASF, Germany, with a molecular weight of at least 70,000 g / mol is taken;

- the moistened mixture is mixed until a plastic homogeneous mass is obtained;

- molded into granules;

- the granules are dried.

The difference of the proposed method of granulation of zeolite is that

- as a binder - granulation liquid - take 33.3-50.0% aqueous solution of the specified copolymer of acrylo-maleic acid brand Sokalan®CP5, manufactured by BASF, Germany;

- the components are taken in the following quantitative ratio, based on the calculation of dry matter,% mass .:

Zeolite powder 80-95 Sokalan®CP5 copolymer 5-20

- in the process of preparation, the mass ratio of the solid phase (zeolite) to the granulation liquid is taken equal to 5: 1;

- zeolite granulation is carried out using wiping sieves intended for granulation of wet pastes, with a mesh with a mesh size of at least 200 μm, which allows to obtain zeolite granules of the required size;

- after granulation and drying, the zeolite is sieved through a sieve with a mesh with a mesh size of less than 200 microns to separate zeolite granules with a size of less than 200 microns;

- from the separated granules with a size of less than 200 microns, the molding mass is re-prepared and granulation is repeated through a wiping sieve, which allows to reduce losses during granulation and to achieve the maximum possible yield of the final product.

To implement the method of producing zeolite, the following components were used:

- crystalline zeolite of the NaA grade manufactured by Salavat Catalyst Plant LLC, STO 05766575-002-2009, Russia;

- crystalline zeolite brand NaA manufactured by Huiying Chemical Products (Quanzhou) Co., Ltd. (China);

- crystalline zeolite brand Doucil MAP production of PQ Corporation, the Netherlands;

- copolymer of acrylic maleic acid Sokalan®CP5, Sokalan®PA25, Sokalan®HP25, molecular weight 3000, 4000, 70,000, respectively, 40% solution, manufacturer

- company BASF, Germany.

A known method of forming particles of the desired size using wiper screens.

Known operations for the classification of solid particles of different fractional composition using sieves with a certain cell size.

It is known to use a solution of a Sokalan®CP5 copolymer with a molecular weight of 70,000 as a binder in a granulation liquid with the addition of alcohols when forming granules in a more complex method of granulating zeolite.

However, to obtain granular zeolite with a simply controlled particle size, the use of wipers is not known. Spray drying does not allow you to adjust the particle size, to obtain the required "narrow" range of particle sizes, the range of particle sizes in spray drying is wider than when using wiping screens.

It is known that zeolite is able to finely disperse calcium ions from aqueous solutions in a finely dispersed state, i.e. in this case, after the dissolution of the zeolite granules with the formation of a stable suspension, when the zeolite particles are uniformly distributed throughout the volume of the solution. In addition to its binding function, the Sokalan®CP5 acryl-maleic acid copolymer is capable of dispersing suspended zeolite particles and inhibiting the reprecipitation of contaminants on tissues, which is very important for CMC.

Granulation of the zeolite with the proposed new method using a Sokalan®CP5 copolymer solution in the indicated concentration range and with the indicated solid to liquid ratio of 5: 1 made it possible to obtain a product with the granule sizes required for the production of synthetic detergents at least 200-400 microns possessing good flowability, mechanical strength, solubility and sorption capacity for calcium. The ratio of the solid phase (zeolite) to liquid (granulation copolymer solution) for the prototype is (2.0-2.6): 1. In the proposed method, the amount of solution used for granulation is less than in the prototype, but its concentration in the binder is greater. With this ratio, the necessary humidity and plasticity of the moldable mass is ensured, with a larger ratio of solid phase to liquid, the mixture will be dry, and the granules will be scattered during molding, not reaching the required size. With a lower ratio of solid phase to liquid, the mixture will be waterlogged, the granules will stick together during wiping, forming a “porridge”, clogging the mesh cells. Thus, the unknown properties of providing the required ductility of the moldable mass, reducing the residual moisture of the zeolite after granulation at low cost for the drying process with a ratio of solid phase to liquid 5: 1.

In the General case, the granulation method is as follows.

Prepare a solution of the Sokalan®CP5 copolymer with a concentration of 33.3-50.0 wt%, based on the ratio of solid phase (g): granulation solution (g) = 5: 1. The prepared granulation solution is gradually added to the zeolite powder with constant stirring. The resulting mixture is thoroughly mixed for 5-10 minutes until a homogeneous plastic paste is obtained. Next, the resulting mass is wiped through a sieve with a mesh size of 200-400 μm, after which the granular zeolite is sieved through a sieve with a mesh with a mesh size of 200 μm to separate zeolite granules with a size of less than 200 μm, from which the molding mass is re-prepared and granulation is repeated through wiping sieve. After granulation, the zeolite is dried at a temperature of 90 ° C for 2 hours.

The proposed method for producing granular zeolite is illustrated by the following examples, the data of which are shown in Table 1. Table 2 shows the characteristics of the obtained zeolite according to these examples.

Sorption capacity is characterized by the value of the binding ability of calcium from aqueous solutions, which was determined in accordance with the method described in the work of L.V. Trubacheva, S.Yu. Lohanina, Bulletin of Udmurt State University, 2005, No. 8, p. 211-222.

The solubility of granular zeolite was estimated as the time between the moment it was placed in water and the formation of a suspension stable in time, without significant sedimentation of zeolite particles on the bottom of the vessel.

Example 1

Prepare a solution of the Sokalan®CP5 copolymer (molar mass of about 70,000 g / mol) with a concentration of 33.3 wt.%, Based on the mass ratio of the solid phase: granulation solution 5: 1. The prepared granulation solution is gradually added to the zeolite powder with constant stirring. The resulting mixture is thoroughly mixed for 5-10 minutes until a homogeneous plastic paste is obtained. Next, the resulting mass is wiped through a sieve with a mesh size of 200 μm, after which the granular zeolite is sieved through a sieve with a mesh size of 200 μm to separate zeolite granules with a size of less than 200 μm, from which the molding mass is re-prepared and granulation is repeated through a wipe sieve. After granulation, the zeolite is dried at a temperature of 90 ° C for 2 hours.

As can be seen from the data in Table 2, this sample has a high rate of solubility and calcium binding capacity. The binder at this content in the composition of the obtained product does not allow the granules to crumble during transportation and storage and at the same time provides good solubility of the granules, while being a dispersant with a large molar mass, which keeps the particles of the dissolved granules in suspension, not allowing them to settle on the bottom of the vessel, which is very important for synthetic detergents not to settle on the fabric during washing. The residual moisture content of granular zeolite after drying is 12.4%. This sample can be used in the manufacture of synthetic detergents.

Example 2

The zeolite is granulated similarly to the sample described in example 1, the difference is that the granulation uses a solution of Sokalan®CP5 copolymer with a concentration of 20.0% by mass. As can be seen from Table 2, the sample of example 2 due to the lower content of the copolymer has a greater solubility time (the time of formation of a homogeneous suspension) and, accordingly, a slightly lower indicator of the binding ability of calcium in comparison with example 1. Due to the lower content of the copolymer its dispersing the effect is manifested to a lesser extent compared to example 1, which leads to the gradual subsidence of a significant number of zeolite particles at the bottom of the vessel, i.e. stable suspension is not observed. The residual moisture content of granular zeolite after drying is 11.6%. Despite optimal hydration, this sample cannot be used in the manufacture of synthetic detergents.

Example 3

The zeolite is granulated similarly to the sample described in example 1, the difference is that the granulation uses a solution of the Sokalan®CP5 copolymer with a concentration of 42.9% of the mass. As can be seen from the data of Table 2, this sample, similarly to the sample of example 1, has a high solubility and calcium binding capacity. The residual moisture content of granular zeolite after drying is 9.7%. This sample can be used in the manufacture of synthetic detergents.

Example 4

The zeolite is granulated similarly to the sample described in example 1, the difference is that the granulation uses a solution of Sokalan®CP5 copolymer with a concentration of 50.0% by mass. As can be seen from the data of Table 2, this sample, similarly to the sample of example 1, has a high solubility and calcium binding capacity. The residual moisture content of the granulated zeolite after drying is 14.4%. This sample can be used in the manufacture of synthetic detergents.

Example 5

The zeolite is granulated similarly to the sample described in example 1, the difference is that during granulation the mass ratio of the solid phase: granulation solution is 4.5: 1. As can be seen from Table 2, the sample of example 5 has performance indicators similar to the sample of example 1. However, due to the large amount of granulation liquid, the molded paste is overmoistened, during the formation through the sieve, the obtained granules stick together, and the mesh holes are clogged. In addition, the granules obtained after drying have a residual moisture content of 30.2%, which does not meet the requirements for zeolites used in the manufacture of synthetic detergents. This sample cannot be used in the manufacture of synthetic detergents.

Example 6

The zeolite is granulated similarly to the sample described in example 1, the difference is that during granulation the mass ratio of the solid phase: granulation solution is 5.5: 1. As can be seen from Table 2, the sample of this example has performance indicators similar to the example of example 1. Due to the large amount of the zeolite solid phase, the molded paste is not moistened, during molding through a sieve, the obtained granules crumble, forming a large amount of dust, which leads to transportation problems and the operation of zeolite and does not meet the requirements for zeolites used in the manufacture of synthetic detergents. This sample cannot be used in the manufacture of synthetic detergents.

Example 7

The zeolite is granulated similarly to the sample described in example 1, the difference is that the granulation uses a solution of the Sokalan® PA25 copolymer with a molar mass of about 4000 g / mol. As can be seen from Table 2, the sample of the example due to the lower molar mass of the copolymer and, as a result, a smaller dispersing effect has a longer solubility time - the time of formation of a homogeneous suspension, and, accordingly, a slightly lower indicator of calcium binding capacity compared to example 1. For the same reason, the formation of a stable suspension is not observed; a significant amount of zeolite particles settles rapidly at the bottom of the vessel. The residual moisture content of granular zeolite after drying is 11.8%. Despite the optimal wetting during the formation of granules, this sample cannot be used in the manufacture of synthetic detergents.

Example 8

The zeolite is granulated similarly to the sample described in example 1, the difference is that the granulation uses a solution of the Sokalan®HP25 copolymer (molar mass of about 3000 g / mol). As can be seen from Table 2, the sample of the example due to the lower molar mass of the copolymer and, as a result, a smaller dispersing effect has a longer solubility time (time of formation of a homogeneous suspension) and, accordingly, a slightly lower indicator of calcium binding capacity compared to example 1. For the same reason, the formation of a stable suspension is not observed; a significant amount of zeolite particles settles rapidly at the bottom of the vessel. The residual moisture content of the granulated zeolite after drying is 15.1%. Despite the optimal wetting during the formation of granules, this sample cannot be used in the manufacture of synthetic detergents.

Example 9

The zeolite in accordance with this example is granulated as follows. Powdered zeolite is pressed into tablets using special pressing equipment at the lowest possible pressure of 7 atm. The resulting tablets are dried at a temperature of 120 ° C for 2 hours, and then crushed to obtain a fraction of 200-400 microns and classified by screening. A fraction of less than 200 microns is again sent to tabletting. The resulting sample compared to the sample of example 1 is poorly soluble, does not form a stable suspension and has a low sorption capacity for calcium. The reason for all of the above, apparently, is the dense packing of particles during molding, the lack of significant secondary porosity of the obtained granules and, as a consequence, the lack of accessibility of ion exchange centers. The residual moisture content of the granulated zeolite after drying is 20.4%. This sample cannot be used in the manufacture of synthetic detergents.

To implement the prototype, powdered zeolite is introduced into the mixer / granulator and sprayed with granulation liquid until a homogeneous mixture is obtained. Granulation fluid is based on a calculation of 49.5% of the mass. 100% of the mass. anhydrous zeolite, from: 20% of the mass. 40% solution of the copolymer brand Sokalan®CP5 (company BASF), 14% of the mass. saturated alcohols of composition C ₁₂ -C ₁₈ , 66% of the mass. water with a mass ratio of solid phase: liquid (2.0-2.6): 1. After mixing for 10-60 seconds, the granulation liquid is sprayed through the nozzle for 1-5 minutes and the mixture is granulated for another 1-3 minutes with continuous stirring. Residual humidity is significant - 19-22%. The granules leaving the mixer are dried with hot flue gases (temperature - 70 ° C) in a fluidized bed. The solubility of zeolite granules was 10 s, the sorption capacity for calcium was about 220 mg CaO / g.

Thus, a simpler method compared to known methods of granulating powdered zeolite using a cheaper and simpler granulation liquid composition with a lower consumption of the expensive Sokalan®CP5 component with the possibility of obtaining granules of a certain size by adjusting the mesh size of the cleaning sieve mesh having operational characteristics is proposed. not inferior to the prototype. With the stated ratio of the solid phase: granulation solution, the requirements for the residual moisture of the zeolite are fulfilled - not more than 20%. At small ratios, the solid phase: granulation solution, as shown in the examples, the residual moisture will be significant, which will require an increase in the drying time of the zeolite after granulation.

Claims (2)

1. A method of granulating a zeolite in which a powdered zeolite is moistened with a granulation liquid, an aqueous solution of a Sokalan® male acid acrylic-maleic acid copolymer made by BASF, Germany, with a molecular weight of at least 70,000 g / mol moistened is taken as a component of the granulation liquid the mixture is stirred until a homogeneous plastic mass is obtained, formed into granules, the granules are dried, characterized in that a 33.3-50.0% aqueous solution of an acrylo-maleic acid copolymer is taken as granulation liquid, in the preparation process, the mass ratio of the solid phase-zeolite to the granulation liquid is taken equal to 5: 1, the zeolite is granulated using wipers, with a mesh with a mesh size of at least 200 μm, after granulation and drying, the zeolite is sieved through a sieve with a mesh with a mesh size of less than 200 microns. 2. The method according to p. 1, characterized in that from the separated granules with a size of less than 200 microns, the molding mass is re-prepared and re-granulation is carried out through a wipe sieve.