KR19990010415A - Method for preparing crystalline layered sodium disilicate - Google Patents

Abstract

The present invention relates to a method for producing crystalline layered sodium disilicate, and more particularly, by using anhydrous sodium disilicate cullet powder of a certain composition ratio as a starting material and adding an aqueous sodium silicate solution as a binder to the granulated granules. After preparing and drying, the granulated granules are put into a kiln and subjected to crystallization to produce crystalline layered sodium silicate, which increases the purity of the product and simplifies the manufacturing process and facilitates process control, compared to the conventional method. Improved production of crystalline sodium bisulfite useful as builders of water softners or detergent compositions that reduce costs and significantly reduce the reactant deposits in the firing apparatus. It is about a method.

Description

Method for preparing crystalline layered sodium disilicate

The present invention relates to a method for producing crystalline layered sodium disilicate, and more particularly, by using anhydrous sodium disilicate cullet powder of a certain composition ratio as a starting material and adding an aqueous sodium silicate solution as a binder to the granulated granules. After preparing and drying, the granulated granules are put into a kiln and subjected to crystallization to produce crystalline layered sodium silicate, which increases the purity of the product and simplifies the manufacturing process and facilitates process control, compared to the conventional method. Improved production of crystalline sodium bisulfite useful as builders of water softners or detergent compositions that reduce costs and significantly reduce the reactant deposits in the firing apparatus. It is about a method.

As a starting material in the present invention (Cullet) is often used as a raw material in the production of aqueous sodium silicate solution, the silica and sodium carbonate in a suitable molar ratio (the ratio of SiO ₂ to Na ₂ O, that is, SiO ₂ / Na ₂ O ) Is a compound consisting of small agglomerates or pieces of amorphous sodium silicate that can be obtained by mixing and heating and melting at a high temperature of about 1000 ~ 1400 ℃.

In addition, layered sodium silicate is a crystalline silicate represented by (Na ₂ O) _x (SiO ₂ ) _y (where y / x changes depending on the crystal structure and usually has a value of 2 to 11). Among them, crystalline sodium sodium silicate, represented by Na ₂ Si ₂ O ₅ , has been reported to have crystallographic α-, β-, γ-, and δ-types, and due to its structural specificity, adsorption characteristics, ions Due to its unique exchange capacity, it is useful for various chemical processes such as catalyst carriers, separation and purification processes. In particular, δ-type crystalline sodium bisulfite has a high binding capacity to hardness components such as Ca ²⁺ , Mg ²⁺ in water and has recently been used as a water softner or detergent composition builder. It is developed and used for various purposes such as (builder).

As a representative method for synthesizing δ-type crystalline lamellar sodium silicate, the following method is known.

U.S. Patent No. 4,585,642 No. and European Patent No. 293 640 number or the like is sodium silicate aqueous solution and adjusting the molar ratio (SiO ₂ / Na ₂ O) of the SiO ₂ to Na ₂ O with a sodium hydroxide solution to 1.9 ~ 2.5 and a spray drier The method of crystallizing at 550-800 degreeC after dehydrating using is known.

However, this manufacturing method uses an aqueous sodium silicate solution which is expensive per unit unit compared to anhydrous sodium silicate, and again, a large amount of water is consumed because a large amount of water present in the aqueous sodium silicate solution is consumed, and dehydrated sodium silicate is very bulky. The larger the size of the crystallization device and the greater the amount of dust generated, the bag filter (bag filter) has a disadvantage that takes a lot of load. In addition, in the early stage of the crystallization process, swelling (foam) due to the separation of residual moisture occurs severely, followed by sintering and shrinkage of the particles and particles between each other and the deposition occurs inside the crystallization apparatus problem in the continuous process It is a factor of occurrence.

Japanese heated portion to the Patent Publication No. 4-238809 discloses a molar ratio (SiO ₂ / Na ₂ O) a sodium silicate aqueous solution adjusted to 1.9 ~ 3.2 on SiO ₂ to Na ₂ O keeping the crystallization temperature range of 680 ~ 830 ℃ The crystallization process was simplified by introducing directly into the crystallization process, but the production of large amount of water vapor in the process of high temperature dehydration caused excessive energy consumption, corrosion of the crystallization device, and the device in case of sudden shutdown. There is a problem that deposition of the reactant can occur inside.

In Japanese Patent Laid-Open No. 3-93649, in order to improve the water resistance, a method of modifying the layered structure by adding alumina component to prepare anhydrous sodium silicate and then grinding and crystallizing is known, but this method also contains a large amount of impurities. There is a problem in that sintering occurs between particles.

The above-mentioned U.S. Patent No. 4,585,642 and U.S. Patent Nos. 5,211,930 and 5,268,156 are commonly heated and dissolved by adding a large amount of water to a cullet to heat and dissolve to form an aqueous sodium silicate (water content: 50 to 60 wt%). The sodium hydroxide solution is added to an aqueous solution of the sodium silicate to adjust the desired molar ratio (SiO ₂ / Na ₂ O) to 50 to 60% by weight of the moisture contained in the process using a spray dryer at a temperature of 140 ° C. or higher. After drying the drying step, the powdery intermediate product is crystallized in a high temperature crystallization process in a firing furnace at a temperature in the range of 600 to 800 ° C. US Pat. No. 4,585,642 adds a step of adding a seed corresponding to the δ-form to prevent the final product from mixing with crystalline sodium bisulfite having various crystal forms. 5,211,930 added a recycle process to the final product to prevent the deposition of the product in the firing apparatus, US Patent No. 5,268,156 is a drying means as a means for suppressing the deposition of deposits and dust generation inside the firing apparatus A method of increasing the bulk density by pulverizing (pulverizing) the powdered intermediate product after the process to about 1 to 50 μm was used.

However, in view of the complexity of the process and apparatus, the above technologies are not only economically disadvantageous in terms of maintaining the quality of the final product, but also require high heat energy processes such as heating, drying, and crystallization. The equipment of the required device is much required, and due to the complicated multi-step whole manufacturing process, it becomes a big problem in the process.

Thus, U.S. Patent No. 5,183,651 proposes a manufacturing method that significantly reduces the device and energy costs required by improving a complicated multi-step manufacturing process that has been pointed out as a disadvantage of the above technologies. In this method, various forms of crystals are not mixed and α-type crystalline sodium disilicate is obtained, which is evaluated as an economically advantageous method, but additional recycling of the final product requires additional addition, and most of the final product is α-. As the crystalline layered sodium disilicate of the type, as shown in U.S. Patent No. 4,820,439 and Japanese Patent Application Laid-open No. Hei 4-238809, the binding capacity of the hardness component in water is much lower than that of δ-type crystalline sodium bisulfate There was a problem that can not be used at all as a builder of water softener or detergent composition.

Accordingly, the present inventors have made efforts to improve the complicated multi-step manufacturing process of the above-described prior arts and to prepare a high purity, high-quality crystalline layered sodium silicate having a δ-type. In Korean Patent Publication No. 95-31902), a granulated granule is prepared by adding a small amount of water required for assembly to a collet powder having a molar ratio pre-adjusted to facilitate phase transition to a δ-type. By introducing the granules into the kiln as it is crystallized, we have proposed a new method that not only simplifies the entire manufacturing process and reduces energy consumption, but also reduces costs and deposits of reactants in the device. have. In this method, however, the water used for the granulation of the cullet powder not only acts as a binder but also as an indispensable element of phase inversion by hydration, wherein the conditions for producing granulated granules are difficult depending on the amount of water added. There are disadvantages. For example, when the amount of water added is small due to the characteristics of the cullet powder, granulation is difficult and the purity of the final product produced after crystallization is poor. When a large amount of water is added, it is converted into a slurry that is difficult to maintain the shape of the granulated product. In order to prepare the optimum granulated granules, it is necessary to control the amount of water added.

The present inventors use an aqueous sodium silicate solution instead of water as a binder component in the granulation process of the crystalline powder in the manufacturing method of crystalline sodium bisulfate according to US Patent No. 5,567,404 (Korean Patent Publication No. 95-31902). The present invention has been completed by finding that the amount of water can be easily controlled due to the binding of the solid component in the binder.

It is therefore an object of the present invention to provide a process for the preparation of crystalline sodium bisulfite which improves the demanding granulation process and improves the purity of the product.

1 is a process diagram schematically showing the manufacturing process of the crystalline layered sodium silicate according to the present invention,

2 shows the X-ray diffraction pattern of the sample prepared in Example 1 of the present invention.

The present invention provides a method for producing a crystalline layered sodium silicate, by adding water to anhydrous sodium silicate powder powder to prepare granulated granules and crystallizing them, in which an aqueous sodium silicate solution is used instead of water as a binder for the anhydrous sodium silicate powder. It is characterized by the preparation of the granulated granules by the addition.

Referring to the present invention in more detail as follows.

The present invention is granulated by adding an aqueous sodium silicate solution containing a certain amount of water as a binder component required for the granulation of anhydrous sodium silicate cullet powder composed of a certain component composition. It is one of the key processes of the present invention that not only serves as a binder to facilitate the size adjustment but also serves to promote the hydration reaction. Therefore, the present invention using an aqueous sodium silicate as a binder is completely different from the process of simply adding water in the prior art, and the role of the water and the mechanism of the process. In other words, it effectively contributes to the granulation of the pulverized cullet powder and is easily removed in the crystallization process, and contributes to the improvement of purity and crushability by uniform crystal formation and pore formation, and the addition amount is very small. It provides a mechanism basis that shortens the process without impeding any problem or post-production properties.

In addition, most of the crystalline sodium bisulfite prepared by the production method of the present invention has a δ-type crystal, which is particularly useful as a water softener or detergent adjuvant.

In the process of preparing crystalline sodium bisulfite according to the present invention, a process of preparing anhydrous sodium silicate cullets by mixing, heating and melting silicate and sodium carbonate, and granulating by adding an aqueous sodium silicate solution to the pulverized powder It consists of a process of preparing a granular material, and the process of crystallizing the granulated granular material by heat baking.

Such a method of preparing the crystalline lamellar sodium silicate of the present invention will be described in more detail by each process as follows.

The first process is a process of preparing a cullet by mixing silica and sodium carbonate so that the molar ratio of SiO ₂ / Na ₂ O is 1.80 to 2.20, melting the solution at 1,000 to 1,400 ° C. for 1 to 3 hours, and then cooling to room temperature. At this time, the molar ratio of SiO ₂ / Na ₂ O is the most important factor that determines the crystal form of the crystalline layered sodium disilicate so as to maintain the molar ratio.

In the second process, the cullet prepared above is pulverized to produce a cullet powder having a particle size of 850 μm or less (D ₅₀ : ≒ 300 μm), wherein the molar ratio of SiO ₂ / Na ₂ O as a binder is 2.0 to 3.3. It is a process of preparing granulated granules (volume density: 1.1-1.6 g / cm <3>) of the diameter of 1-50 mm in diameter by adding aqueous sodium silicate (solid content: 15-40 weight%).

If the particle size of the collet powder is larger than 850 μm, the residence time required for granulation is long, and the time required to penetrate into the granulated material with high heat energy during crystallization becomes too long, so that physical properties in the crystallization process of the target product are too long. There is a problem of deterioration. The bulk density of the cullet powder is 0.5 to 0.6 g / cm 3, and the amount of ignition loss at 700 ° C. is 0.4 to 1.0 wt%.

In addition, the aqueous sodium silicate solution used as a binder for granulating the powder powder preferably maintains a molar ratio of SiO ₂ / Na ₂ O of 2.0 to 3.3. When the molar ratio is out of the above range, a large amount of a Or a β-form is generated and present as an impurity. In addition, the solid content of the sodium silicate aqueous solution is 15 to 40% by weight. If the solid content is less than 15% by weight, the amount of water present is large, so that control of the granulation process is not easy, and when the content exceeds 40% by weight. The viscosity of the solution is high, there is a problem that uniform addition to the cullet powder is difficult.

Sodium silicate aqueous solution having the above conditions is added within the range of 10 to 30% by weight with respect to the cullet powder, if the addition amount is less than 10% by weight will be present in the wet powder form without granulation, if it exceeds 30% by weight Due to the excessive moisture is changed into a slurry phase there is a problem that can not be assembled.

The granulated granules thus prepared have a diameter of 1 to 50 mm. If the particle size is less than 1 mm, the granule size is too small to maintain a constant residence time in the crystallization apparatus. There is a problem in that it is difficult to fast heat transfer into the interior of the assembly to produce some impurities. The bulk density of the granulated granules thus prepared is in the range of 1.1 to 1.6 g / cm 3.

In addition, in the present invention, any of a disc granulator, a compression molding machine, a cylindrical granulator, a fluidized bed granulator, and the like can be used as the granulator.

The third step is a step of drying the granulated granules prepared above and heating and calcining to obtain crystalline sodium bisulfite as an object of the present invention.

In the present invention, the granulated granules are dried before being put into the continuous firing apparatus, thereby removing the adhesiveness of the aqueous sodium silicate component on the surface of the granulated granules, thereby eliminating the phenomenon that the granules adhere to each other and transporting the granulated substances. In addition to facilitating, there is an advantage of facilitating the phase change during crystallization by promoting the hydration reaction by the moisture occurring inside the granules. However, if the drying temperature is too high, impurities are formed, resulting in a problem that the purity of the product falls, it is more preferable to carry out the drying process until the water evaporation rate is 0.2 to 1.0% by weight in the temperature range of 80 ~ 200 ℃. At this time, the high temperature heat source used in the drying process has the advantage of reducing the energy consumption by using the exhaust gas discharged from the firing apparatus of the next process. As a result, the dried granulated granules have a bulk density of 1.1 to 1.6 g / cm 3.

The granulated granules subjected to the drying process are crystallized at 0.1 to 1 hour at 650 to 770 ° C. in a rotary firing furnace, which is a continuous firing apparatus, to obtain a material having a bulk density of 0.1 to 0.5 g / cm 3, and then pulverized using a ball mill. . At this time, since the crystal form produced varies depending on the crystallization conditions, it is necessary to crystallize in the above range to obtain a high quality δ-type crystalline layered sodium silicate having high purity.

The characteristics of the method for producing the crystalline layered sodium di silicate according to the present invention as described above are as follows.

First, by using the molar ratio of SiO ₂ / Na ₂ O in the cullet, which affects the purity of the final product, in the range of 1.80 to 2.20, granulating and calcining by adding only a small amount of aqueous sodium silicate solution required for granulation, Through a greatly simplified manufacturing process, most of them are of δ-type, so that a final product suitable for use as a water softener or detergent adjuvant can be obtained.

Second, since there is no need for a device for heating, dissolving, drying, and recycling, which is commonly used, it not only simplifies the entire manufacturing process and saves enormous high-temperature energy, but also reduces the time required for the entire manufacturing process. There is an economic advantage that can greatly reduce the unit output by dramatically reducing

Third, the use of aqueous sodium silicate as a binder facilitates the control of the granulation process and eliminates the problems that may occur during the storage and transfer of granular materials through a drying process that dries the surface of the granulated material. The granular granules are uniformly crystallized in the firing apparatus, and no sedimentation occurs in the kiln, and local sintering is also prevented by putting them into the kiln in the form of granules having only moisture. A high purity crystalline layered sodium disilicate, consisting mostly of δ-forms, is obtained.

Crystalline layered sodium silicate of the present invention prepared by the above method has a calcium ion binding capacity of 98 to 108 mgCa ²⁺ / g, magnesium ion binding capacity of 78 to 86 mgMg ^{2 +} / g at 25 ℃ in a known method It was superior to that prepared by the above, and its crystal phase was also mostly in the δ-form.

When the present invention is described in detail based on the embodiments as follows, the present invention is not limited thereto.

Example 1

600.0 g of quartzite (Australia, Cape Carpenterium) dried at 120 ° C. for 5 hours and 531.9 g of sodium carbonate (Sweden, Solvay) dried at 350 ° C. for 5 hours were respectively weighed. , Ball (φ: 20 mm), pulverized and mixed for 1 hour, put about 1 kg in an alumina crucible (heat, Inc., Model 46200), heated and melted for 2 hours at 1200 ℃ in an electric furnace (USA 46, model 46200) After cooling to room temperature, about 700 g of a transparent cullet mass was obtained. This was analyzed by liquid sodium silicate analysis (KS-M-1415) and found that the molar ratio of SiO ₂ / Na ₂ O was 2.03.

The cullet mass was first crushed into small pieces in a jaw crusher (Korea, made from large powders), and then pulverized for 3 hours with a ball mill (material: alumina, capacity: 3.6 l, ball: φ 20 mm). And classified to make the cullet powder (volume density: 0.5 to 0.6 g / cm 3) having a particle size of 850 μm or less (D ₅₀ : ≒ 300 μm) at a temperature of 700 ° C. to be 0.40 wt%. Take 500g of cullet powder and put it into disc type granulator (Korea, Yeongjin Machinery) and rotate it at 15rpm. Sodium silicate aqueous solution (solid content: 30% by weight, Sinheung silicate) with a molar ratio of SiO ₂ / Na ₂ O is 2.26 A spherical granulated granule having an average diameter of about 17 mm was obtained by dropping it so that the amount of sodium silicate added while forming granulated granule was about 18% by weight.

The granulated granules were dried in a blow dryer for 30 minutes (moisture evaporation rate: 0.5% by weight, bulk density: 1.31 g / cm 3), and then maintained at 725 ° C. in a rotary kiln (US, Lindberg, Model 54579) was crystallized for 20 minutes under conditions of an inclination angle of 0.5 ° and rotational speed of 8 rpm. In this process, no product adhesion occurred in the apparatus, and 498 g of white porous crystalline layered sodium silicate expanded in bulk density of 0.26 g / cm 3 while maintaining the initial granular form.

Example 2

500 g of the collet powder obtained by treatment under the same conditions as in Example 1 was placed in a disc-shaped granulator and rotated at 15 rpm, and an aqueous sodium silicate solution having a molar ratio of SiO ₂ / Na ₂ O of 3.20 (solid content: 30 wt%, emerging silicate) Xiii) 18 wt% was added to form granulated granules under the same conditions as in Example 1. The crystalline layered sodium silicate was prepared by the same treatment as in Example 1 below.

Comparative Example 1

The crystalline layered sodium silicate was prepared by crystallizing and pulverizing the collet powder obtained by treating under the same conditions as in Example 1 under the same conditions as in Example 1 without undergoing a granulated granule manufacturing process. In the manufacturing process, the product melted and adhered to the inside of the sintering device. A large amount of dust was generated in the raw material input process, and the disintegration property of the product due to sintering was poor.

Comparative Example 2

Crystalline layered sodium silicate was treated under the same conditions as in Example 1 using a cullet (molar ratio of SiO ₂ / Na ₂ O: 2.50) obtained by quantifying 600 g of silica and 432.0 g of sodium carbonate under the same conditions as in Example 1. Was prepared.

Comparative Example 3

To 500 g of the collet powder obtained by treating under the same conditions as in Example 1, 125 g of water was added instead of an aqueous sodium silicate solution to prepare granulated granules, and crystallized and pulverized under the same conditions as in Example 1 to form crystalline sodium bisulfate. Prepared.

Experimental Example 1: Measurement of hardness component binding capacity

The products prepared in Examples 1 and 2 and Comparative Examples 1 to 3 were pulverized and classified in a ball mill for 30 minutes to adjust the particle size to 43 to 104 μm, and then Ca ²⁺ and Mg ²⁺ binding capacity in the following manner. Was measured, and the results are shown in Table 1 below.

(1) Ca ²⁺ binding capacity measurement

After weighing about 1.0 g of the sample, it was placed in a stirrer maintained at 25 ° C and 1000 ml of hard water (Ca ²⁺ aqueous solution, hardness 200 mgCa ²⁺ / L) was added thereto. After stirring for 15 minutes, the filtrate was immediately filtered, and 25 ml of the filtrate was accurately taken into a 100 ml Erlenmeyer flask, and 2-3 ml of NH ₃ -NH ₄ Cl buffer (pH 10) was added thereto. The EBT indicator was added thereto, titrated with 0.01 M EDTA standard solution, and Ca ²⁺ binding capacity was calculated using Equation 1 below.

In Formula 1, t is EDTA consumption (ml); w is the sample weight (g); f is the factor of the used EDTA solution.

(2) Mg ²⁺ binding capacity measurement

After weighing about 1.0 g of the sample, it was placed in a stirrer maintained at 25 ° C. and 1000 ml of hard water (Mg ²⁺ aqueous solution, hardness 120 mgMg ²⁺ / L) was added thereto. After stirring for 15 minutes, the filtrate was immediately filtered and 25 ml of the filtrate was taken accurately and placed in a 100 ml Erlenmeyer flask, 0.5 ml of potassium cyanide solution (10%), several drops of hydroxyl ammonium chloride solution (10%) and NH ₃ -NH ₄ Cl buffer. (pH 10) 2-3 ml were added. The EBT indicator was added thereto, titrated with 0.01 M EDTA standard solution, and Mg ²⁺ binding capacity was calculated by Equation 2.

In Equation 2, t is the EDTA consumption (ml); w is the sample weight (g); f is the factor of the used EDTA solution.

division Molar ratio of SiO ₂ / Na ₂ O Ca ²⁺ binding amount (mgCa ²⁺ / g) Mg ²⁺ binding amount (mgMg ²⁺ / g) X-ray diffraction Cullet Sodium Silicate Aqueous Solution Example 1 2.03 2.26 108.6 86.5 δ-Na ₂ Si ₂ O ₅ Example 2 2.03 3.20 98.7 78.7 δ-Na ₂ Si ₂ O ₅ Comparative Example 1 2.03 - 65.7 56.5 α, β, δ-Na ₂ Si ₂ O ₅ Mixture Formation Comparative Example 2 2.50 2.26 62.4 51.7 α, β, δ-Na ₂ Si ₂ O ₅ Mixture Formation Comparative Example 3 2.03 - 97.6 76.9 δ-Na ₂ Si ₂ O ₅

According to Table 1, in Examples 1 to 2 according to the present invention, the final product showed excellent hardness component binding ability, and most of the crystal phases were δ-Na ₂ Si ₂ O ₅ . On the other hand, in Comparative Example 1 and Comparative Example 2, the final product showed a low hardness component binding capacity, and included impurities such as α-type and β-type in addition to the δ-type. In addition, Comparative Example 3 using water as a binder was somewhat inferior in physical properties compared to Example 1, the granulation process was much more difficult than Examples 1 and 2.

Experimental Example 2 X-ray Diffraction Analysis

The product prepared in Example 1 was pulverized and classified in a ball mill for 30 minutes to adjust the particle size to 43-104 μm, followed by crystallinity using an X-ray diffractometer (Digaku, Japan, D / MAX-3B). Was investigated. As the analysis conditions, CuKα target and Ni filter were used, and the relative intensity was measured with a diffraction angle of 5 to 50 ° and a count range of 5000 cps with an output of 15 mA and 35 KV.

Relative strengths characteristic of δ-crystalline crystalline sodium bisulfite as defined in the Joint Committee on Powder Diffraction Standard (22-1396) of the United States in relation to the X-ray diffraction analysis are shown in Table 2 below. In addition, the X-ray diffraction characteristics of the crystalline sodium bisulfate prepared in Example 1 according to the present invention are shown in Table 3 and FIG. 2.

D-SPACE (10 ^-8cm ) Relative strength 6.88 (± 0.06) 0 to 24 4.90 (± 0.05) 0 to 24 3.93 (± 0.07) 75-100 3.78 (± 0.05) 50 to 74 3.44 (± 0.05) 0 to 24 3.02 (± 0.06) 25-49 2.72 (± 0.05) 0 to 24 2.53 (± 0.06) 0 to 24 2.42 (± 0.06) 25-49 2.09 (± 0.05) 0 to 24 1.98 (± 0.07) 0 to 24 1.84 (± 0.05) 0 to 24

2θ D-SPACE (10 ^-8cm ) Relative strength 12.79 6.91 5 14.59 6.07 12 17.98 4.93 13 21.10 4.21 13 22.36 3.97 100 22.97 3.87 7 23.45 3.79 40 24.45 3.64 10 25.80 3.45 10 26.87 3.31 13 28.74 3.10 7 29.50 3.02 20 30.71 2.91 9 31.41 2.84 14 32.79 2.73 6 34.92 2.56 7 35.29 2.54 6 35.96 2.49 11 37.01 2.42 37 43.07 2.10 17 43.73 2.07 5 44.53 2.01 4 47.27 1.92 5 48.24 1.87 7 48.92 1.86 5 49.81 1.83 5 49.16 1.82 7

Table 3 is an X-ray diffraction analysis of the crystalline sodium bisulfate prepared in Examples according to the present invention 2.42, 3.78, 3.93 is the main characteristic value of the typical δ-crystalline crystalline sodium bisulfate shown in Table 2 , Corresponding to the D-SPACE value of 6.88, it can be seen that the final product of the present invention is composed mostly of δ-form.

As described above, the production method according to the present invention makes the composition of the cullet powder within a specific range so that the δ-type layered crystals occupy most of the final object, and is easily powdered to a certain particle size. Aqueous solution of sodium silicate is added to remove the problem of granulation process by drying granulated granules, and very simple to obtain crystalline sodium sodium silicate having excellent physical properties in crystallization of granulated granules. Has

Claims (7)

In the method for producing a crystalline layered sodium silicate, by adding a binder to anhydrous sodium silicate powder powder to prepare a granulated granule and crystallize it, the crystalline layered sodium silicate, characterized in that the aqueous solution of sodium silicate is used as the binder Manufacturing method. The method of claim 1, wherein the aqueous sodium silicate solution has a molar ratio of SiO ₂ / Na ₂ O of 2.0 to 3.3 and a solid content of 15 to 40% by weight. The method for producing crystalline sodium bisulfate according to claim 1 or 2, wherein the aqueous sodium silicate solution is added in an amount of 10 to 30% by weight based on the anhydrous sodium silicate collet powder. The crystalline layered disilicate acid according to claim 1, wherein the anhydrous sodium silicate powder powder has a molar ratio of SiO ₂ / Na ₂ O of 1.80 to 2.20 and a pulverization particle size of 850 µm or less (D ₅₀ : 300 µm). Method of producing sodium. The method for producing crystalline sodium bisulfite according to claim 1, wherein the granulated granules have a diameter of 1 to 50 mm. The method of claim 1, wherein the crystallization process is a process of heating and baking for 0.1 to 1 hour at a temperature of 650 ~ 770 ℃. The method of claim 1, wherein the calcium ion binding capacity measured at 25 ° C is 98 to 108 mgCa ²⁺ / g, the magnesium ion binding capacity is 78 to 86 mgMg ²⁺ / g, and has a δ-type crystal form. Crystalline layered sodium disilicate prepared by