KR900001487B1 - Method for production of zeolite - Google Patents

Abstract

A zeolite is produced by manufacturing sucessively homogeneous and amorphous alumino silicate gel by supplying and hydrogeling silicate of soda solution and aluminate of soda solution into a flowing mixer, converting the gel (where viscosity is 550 - 15000 cp) to fluid alumino silicate sol (where viscosity is 20 - 1400 cp) by charging torque, aging the sol at 5 - 70 deg. C for 0 - 72 hours, and crystallizing at 50 - 120 deg. C for 0.2 - 24 hours into mean particle size 2 - 4 micron.

Description

Method of manufacturing zeolite

Figure 1 shows the flow of the zeolite crystal ripening process using the present invention.

Figure 2 shows the relationship between the temperature of the reaction solution and the hydrogelation time introduced into the continuous flow blender according to the present invention.

3 is a comparative observation of the zeolite products synthesized according to the present invention and commercial zeolites by SEM microscopy.

In the present invention, by simultaneously introducing a freshly prepared aqueous solution of sodium silicate and aqueous solution of sodium aluminate at a constant concentration at a constant flow rate through a continuous flow blender (FIG. 1), homogeneous mixing is possible in an equivalent amount in the flow, followed by a torque immediately before solidification occurs. Torque was added to prevent excessive hydrogelation and localization.

As a result, an amorphous aluminosilicate sol (sol) having a uniform viscosity and excellent fluidity can be obtained, which was used as a raw material for crystallization of zeolite.

Features of the present invention are less grit (granular solid matter) mixture and excellent fluidity, compared to the conventional batch hydrogel, the zeolite products synthesized therefrom have high yield and narrow particle size distribution width. Atomization crystallization is possible, and hydrogelation

In particular, in the present invention, a method for preparing a zeolite 4A powder for detergent builders with an average particle diameter of 2 μm or less, 4 μm or less, particle size distribution accumulation rate of 90% or more and calcium ion exchange capacity of 270 mg CaCO ₃ / g zeolite (anhydride) or more It is about.

Zeolite is a crystalline aluminosilicate represented by the following general formula. In other words,

M is a cation having an atom of n, and w represents the number of molecules of crystal water. The ratio of y to x, y / x, varies with the crystal structure and usually has a value of 1-5. These zeolites are unique in their adsorption properties, catalytic activity and ion exchange ability due to their structural specificity, and thus have various uses in various chemical processes such as separation and purification processes. In particular, zeolite 4A has been widely used as a substitute for phosphate detergent additives, which have excellent cation exchange capacity and high ecological stability, causing water pollution.

Since zeolite is a water-insoluble crystalline compound, ion exchange rate, sedimentation rate, fiber surface adhesion, etc. become important property standards during washing process. In order for zeolite to fully show its efficacy as a detergent adjuvant, a fine uniform particle size distribution is required above all.

In particular, in Korea and Japan, where washing conditions are significantly different from those in Europe, detergent zeolites should have finer powder levels due to lower washing temperatures, shorter washing times, and smaller quantities.

Zeolite synthesis is based on the clay process and the hydrogel process.

The clay method is a method of activating aluminosilicate clay such as Kaolin and hydrothermally synthesizing it in an aqueous solution of caustic soda. U.S. Patents 3,114, 603, 4,075,280, German Patent 2,852,674, European Patent 0103799, French Patent 2,543,939, Although it is reported in Japanese Patent No. 55-18277 and the like, it is evaluated that it is difficult to remove impurities contaminated in the crystal lattice of natural ore, and is unsuitable for producing high quality functional zeolite due to low yield of product and wide particle size distribution. On the other hand, the aqueous gelatinization method is a method of converting the amorphous aluminosilicate gel into zeolite crystals by hydrothermal reaction, and most synthetic zeolites are produced by this method.

Early patents related to this can be U.S. Patent Nos. 2,882,243, 2,882,244, German Patents 1,038,016, 1,038,017, and the like. Aluminosilicate gels are flowable by injecting or emulsifying alumina soda solution into silicic acid or sodium silicate solution. After conversion to a sol, it is aged and aged to convert to zeolite crystals. However, the process of amorphous aluminosilicate formation varies significantly over time, and the exact chemical reactor conduct is still unknown.

Although it is interpreted as a stage in which crystalline species are formed, miscellaneous silicate polymer intermediates may be formed depending on the mixing method, and thus, the physical and chemical properties of the final product may be greatly changed.

Conventionally, Al ³⁺ ions, which are positive elements, are frequently added because the solution of sodium aluminate is added dropwise to an excess silicate solution and the stirring is continued until the equivalent molar ratio is terminated.

In Japanese Patent No. 55-90417, a small amount of alumina is added to an aqueous solution of sodium silicate to prepare an active sodium silicate solution, and a sodium aluminate solution is added to it in a short time to obtain an amorphous aluminosilicate gel having a high silicate component. A method of producing a granular zeolite with an average particle diameter of 2 μm or less by crystallizing at 占 폚 is described. In this method, since the silica and alkali content in the aluminosilicate gel are excessive compared to the existing method, it is difficult to manufacture a product having a uniform physical property because the energy loss during crystallization is large and complex side reactions are easily involved. In addition, since the silica component and the alkali component remain in the alkaline mother liquor after the crystallization process, the recovery and use thereof are restricted.

German Patent No. 2,856,278, US Patent No. 4,275,048, and Japanese Patent No. 55-90417 provide a uniform amorphous aluminosilicate obtained by continuously spraying a sodium silicate solution and a sodium aluminate solution with air through a nozzle. A method for producing a fine zeolite having a particle diameter of 3 μm or less is described. This method has the advantage of being able to manufacture a fine amorphous aluminosilicate continuously without applying high shear force because the two solutions are mixed in the sprayed state.

However, since the two components of the raw material solution to increase the dispersion through the nozzle, in consideration of the water vaporization during the spray mixing process, the original water content of the two raw materials solution is higher than the existing method, the energy loss to follow this is large.

In addition, the extremely fine aluminosilicate gel fine particles that can be produced during the hydrogelation by the nozzle passage do not settle and are mixed with the discharged gas, thereby causing a reactant loss.

In the present invention, the sodium silicate solution and the sodium aluminate solution were simultaneously injected into a continuous flow mixer, and hydrogelized during the flow process to form a uniform aluminosilicate gel.

Subsequently, before the rapid increase in viscosity or the solidification phenomenon, torque is applied to convert into a fluidized sol and then crystallized.

Sodium silicate solution was prepared by dissolving H ₂ O in solid sodium silicate (Cullet) at 120-180 ℃ and adding alkaline mother liquor (described later). It was.

Na ₂ O / SiO ₂ = 0.3-1.0

H ₂ O / Na ₂ O = 10-80

Viscosity: 3-150cp

However, unless otherwise stated, all the viscosities were measured using a Hake viscometer at 25 ° C. and then temperature corrected.

Sodium aluminate solution is a net solution of alkaline mother liquor recovered from the zeolite synthesis process.

Na ₂ O / Al ₂ O ₃ = 0.7-2.1

H ₂ O / Na ₂ O = 10-47

Viscosity: 2-85cp

Freshly prepared soda and aluminate soda solutions were stored in different storage tanks (1, 2) as shown in FIG. Both reactants were maintained at a constant temperature between 0-60 ° C. and allowed to co-inject into the blender at a constant flow rate through a metering pump (3). The blender 5 used for this purpose was a Y-shaped tube with a check valve attached to the diameter D, and the reactants were mixed in equivalent amounts during the t-hour flow along the length L and the hydrogelation reaction proceeded.

Depending on the flow rate, D and L can be adjusted and baffles can be attached for optimum flow rate and turbulence, and homogeneous viscosity (550-15,000 cps) alumino when the reaction blend reaches the bottom of the blender Silicate was allowed to form. The reaction product was subsequently introduced into a spiral kneader or the like to give an appropriate torque to convert into a more stable fluidized sol having a viscosity of 20-1400 cps without a sudden increase in viscosity or severe aggregation. Preferably it is possible to enable a continuous process by using an improved kneader.

The reactant viscosity at this stage increases instantaneously according to conventional batch blending processes, reaching tens of thousands to hundreds of thousands of cps, making uniform blending virtually impossible. The molar composition ratio and viscosity of the aluminosilicate hydrogel prepared by this method are as follows.

SiO ₂ / Al ₂ O ₃ = 1.7-2.1

Na ₂ O / SiO ₂ = 1.1-2.3

H ₂ O / Na ₂ O = 15-56

Viscosity: 20-450cp

In order to prepare 4A zeolite for detergent adjuvant, the amorphous aluminosilicate obtained above was aged in a crystallizer (8) equipped with a stirrer (7) for 5-70 ° C, 0-72 hours, and 50-120 ° C, 0.2- Crystallization was carried out for 24 hours to prepare a zeolite powder having an average particle diameter of 2 μm or less, a particle size distribution accumulation ratio of 4 μm or less, 90% or more, and a calcium ion exchange capacity of 270 mg CaCO ₃ / g zeolite (anhydride) or more.

In the hydrogelation process of the present invention, the residence time, which is different from the temperature, injection rate, length and diameter of the continuous flow mixer, and the shape of the baffle, is a very important factor in the sodium silicate solution and the sodium aluminate solution.

If the residence time is too short, the mixture of the two solutions may be insufficient, so that the solution is introduced into the kneader as it is and becomes a semi-sol sol. During the aging process, the unreacted solution in the sol gels again to form non-uniform aluminosilicates. If the residence time in the continuous flow blender is too long, the two solutions will gel completely, causing a sharp rise in viscosity or clogging of the outlet, making continuous hydrogelation operations impossible.

Therefore, proper residence time adjustment is very important. An important parameter in controlling the residence time is

2 shows the relationship between the temperature of the reaction solution flowing into the continuous flow mixer and the hydrogelization time. As the temperature of the solution increases, the gel formation time decreases logarithmically. In the present invention, the temperature of the two solutions is maintained at a constant temperature between 0-60 ° C, and the combustion flow reactor adjusts the diameter, length, and the number and shape of the baffles so that the in-flight residence time is 10 ³ seconds or less when the two solutions are introduced. This resulted in the formation of an aluminosilicate gel of uniform viscosity (550-15,000 cps).

Example 1

10.65 kg of H ₂ O was added to 4.73 kg of solid sodium silicate (Na ₂ O: SiO ₂ = 1: 3.5), dissolved at 145 ° C (60 psig), and 17.06 kg of 7.8% aqueous NaOH solution was added thereto. Was prepared. Next, an aqueous 16.1% NaOH solution was added to 4.9 kg of aluminum hydroxide (64% of Al ₂ O ₃ ), dissolved at 140 ° C. (50 psig), and 7.9 kg of 7.8% NaOH aqueous solution was added to prepare a solution of alumina soda having a viscosity of 7.3 cp. . Both solutions were stored in 30 L polyethylene containers respectively to maintain the temperature of the reactants at 25 ° C, respectively.

Next, the flow rate of the sodium silicate solution and the sodium aluminate solution was adjusted to 1.5 L / min through a metering pump and injected into the continuous flow blender. The blender used was a Y-shaped tube with a total length of 400 mm and a diameter of 10 mm, and the four The baffle was attached, and the installation angle was 90 ° from the horizontal, and the in-vehicle residence time of the two solutions was about 1.5 seconds. The aluminosilicate gel with a viscosity of 1200 cps was injected into a double screw type kneader with a length of 150 mm and 120 revolutions per minute to convert to a flowable sol with a viscosity of 65 cps and

After crystallization, the solid cake was separated from the alkaline mother liquor and washed with 56 L of demineralized water. The recovered slurry was then spray dried to obtain a zeolite 4A powder.

Calcium ion exchange capacity: 295mg CaCO ₃ / g Zeolite (anhydride)

Average particle size: 1.7 μm

Particle size distribution (accumulation rate): 90% of 3.2μm or less

10% below 1.1μm

Whiteness: 98 (Hunter Color Test, L value)

Thermal reduction (800 ℃): 20.3%

Example 2

In the same manner as in Example 1, a sodium silicate solution and a sodium aluminate solution were prepared. Next, the temperature of the two solutions was maintained at 50 ° C. and the length of the continuous flow mixer of Example 1 was adjusted to set the residence time of the two solutions to 0.02 seconds.

Hereinafter, zeolite 4A was synthesized in the same manner as in Example 1.

The physical properties of the product are as follows.

Calcium ion exchange capacity: 290mg CaCO ₃ / g zeolite (anhydride)

Average particle size: 1.3μm

Particle size distribution (accumulation rate): 7.6μm or less 90%

0.3μm or less 10%

Whiteness: 98 (Hunter Color Test, L value)

Thermal loss (800 ℃): 18.5%

Claims (5)

Simultaneous injection of sodium silicate solution and sodium aluminate solution into the continuous flow compounder and hydrogelized to the equivalent weight during the flow process; (Na ₂ O) _1.9-4.8. (Al ₂ O ₃ ). (SiO ₂ ) _1.7-2.1. (H ₂ O) Homogeneous amorphous aluminosilicate gel represented by _28.5-268.8 was continuously prepared and torqued The solution was converted into a flowable aluminosilicate sol and aged for 0-72 hours at 5-70 ° C, followed by crystallization at 0.2-24 hours at 50-120 ° C.Average particle size distribution of less than 2μm, cumulative particle size distribution of 4μm or more, 90% of calcium ion A method for producing zeolite 4A having a exchange capacity of 270 mg CaCO ₃ / g zeolite (anhydride) or more. The sodium silicate solution of claim 1 is prepared by adding H ₂ O and caustic soda to sodium silicate and dissolving at 120-180 ° C. to have the following molar composition ratio and viscosity. Na ₂ O / SiO ₂ = 0.3-1.0 H ₂ O / Na ₂ O = 10-80 Viscosity: 3-150cp The sodium aluminate solution of claim 1 is prepared by adding an alkaline mother liquor and an additional amount of caustic soda to aluminum hydroxide and dissolving at 100-180 ° C. to have a molar composition ratio and viscosity. Na ₂ O / Al ₂ O ₃ = 0.7-2.1 H ₂ O / Na ₂ O = 10-47 Viscosity: 2-85cp The method of claim 1 wherein the reaction is maintained at 0-60 ° C. constant temperature during the hydrogelation process, and the viscosity of the amorphous aluminosilicate gel produced by adjusting the residence time in the continuous flow mixer is maintained at 550-15,000 cp. The method of claim 4 wherein the amorphous aluminosilicate gel is subjected to torque to convert to a flowable sol having a viscosity of 20-1400 cp.

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