JPS59195523A - Manufacture of zeolite - Google Patents

Abstract

PURPOSE:To reduce the production cost of zeolite by using amorphous hydrated silica, a by-product of the synthesis of cryolite and aluminum fluoride, as a silica source in manufacturing zeolite used for synthetic detergent. CONSTITUTION:In manufacturing zeolite which is suitably used for synthetic detergent, amorphous silica contg. 40-60% water content, a by-product of the synthesis of cryolite or aluminum fluoride from silico-fluoride is used as a silica source. For the production, Al(OH)3 is dissolved in an aq. soln. of NaOH, and said amorphous hydrated by-product silica, in powdery form or as a suspension in water or an aq. soln. of NaOH, is added to the soln., and reacted. In this case, SiO2, Al2O3, Na2O and water in the by-product silica, Al(OH)3, and NaOH are used to satisfy the ratio shown in equation (1). The reaction is carried out while agitating violently, and zeolite is crystallized at 80-105 deg.C under ordinary pressure. Thus, zeolite is manufactured at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for producing zeolites using a hydrous amorphous silica as the silica source. More specifically, the silica containing 40 to 60% by weight of water (hereinafter referred to as by-product silica), which is produced as a by-product when synthesizing cryolite or aluminum fluoride using silicofluoride, is used as a silica source. The present invention relates to the manufacturing method. □ The demand for zeolite increased rapidly as this substance began to be incorporated into synthetic detergents, and it has now become the social mission of zeolite manufacturers to produce and supply zeolite at the lowest possible cost.

Zeolites are usually produced by a process consisting of a hydrothermal reaction of a composition consisting of silica, alumina and soda. There are two typical methods for producing zeolite for detergents: One of them is sodium silicate (water glass)
and sodium aluminium;! ; One method consists of combining J and 84 to crystallize it, and the other method consists of adjusting the composition of pretreated silica salt-resistant clay minerals and crystallizing them. In the former case, separate equipment is required to dissolve the silica source and the alumina source in the sodium hydroxide solution. This method allows easy purification of raw materials and allows stable production of zeolite with excellent whiteness and ion exchange ability. Since the manufacturing process and operation for 1 m are complicated, equipment investment and operating costs tend to be high, and ultimately it is difficult to manufacture zeolite at a low cost. In the case of the latter, it was developed for the purpose of utilizing naturally produced and inexpensive raw materials, from the viewpoint that it does not have the disadvantage of high raw material cost I. in the former. However, since the raw material is a natural mineral product, it contains many undesirable components such as those that interfere with zeolite crystallization, components that have poor reactivity, or components that reduce the physical properties or quality of the product zeolite. May include. Therefore, in the latter method, in order to improve the purity or reactivity of the natural raw material, it is necessary to pre-treat the raw material, such as by treating it with alcohol or by pulverizing and calcining it. Therefore, even if the latter method is adopted, the final manufacturing cost will end up being about the same as when the former method is adopted. However, the latter type of zeolite products tend to be slightly inferior in quality to the former ones, such as being colored reddish yellow.

In view of the above-mentioned state of the known methods for producing zeolite, the present inventors have conducted extensive research into an economical method for producing zeolite particularly suitable for use in synthetic detergents. As a result, the above-mentioned by-product silica was found to have the following characteristics: (1) It is highly chemically active and easily disperses or dissolves in a low concentration aqueous sodium hydroxide solution at a temperature of about 0.80°C. When this product is used as a silica source for zeolite products, it is possible to produce zeolite suitable for detergents using simpler manufacturing equipment, which is comparable to the case where sodium silicate is used as a silica source using a known method. The present invention was achieved by discovering the fact that it can be manufactured at low cost.

As is clear from the following description, an object of the present invention is to provide a simple and efficient method for producing zeolite by effectively utilizing a specific by-product silica that has not been used much in the past.

The present invention focuses on the main structure of the description (1) and the embodiment structure of the following (2).

(1) Hydrous amorphous silica, aluminum hydroxide, sodium hydroxide, and water, which are produced as by-products when synthesizing cryolite or aluminum fluoride using silicofluoride, are converted into Na2O, which is their constituent quarter, Al2O3 and 5i02 and H2O are all in molar ratio or mol% (NaxO) / [Al2O3) = 1.5 ~ 3
．． 0(Sin,,) / (A1203) = 1.
5 to 2.1 = 90 to 96 mol%. Mix and react with typical stirring, and crystallize at 80 to 105°C. IIF
'6! I.

A method for producing zeolite.

(2) Dissolving aluminum hydroxide in an aqueous sodium hydroxide solution, and mixing wood-containing amorphous silica or a suspension of the substance in water or an aqueous sodium hydroxide solution into the solution obtained by the dissolution. The method described in section (1).

The structure and effects of the present invention will be explained in detail below. First of all, the above-mentioned by-product silica used in the present invention is, for example, a by-product produced during the production of phosphoric acid in the phosphorus dairy manufacturing industry, and also a by-product produced when the recovered fluorine compound is recycled. This stuff usually has a moisture content of 40-60%, 0.5
It is recovered as an aggregate of primary particles with a specific surface area of ~50rn'/g and a particle size of 1 gm or less.

In the method of the present invention, the by-product silica is in a hydrated state! It is extremely important to use the zeolite in the reaction up to 1:1 in order to finally produce a fine particle zeolite with a large ion exchange capacity.

For reference, the following known silicas a to d do not produce desirable results even if used in place of the by-product silica in the method of the present invention for the following reasons. Namely, a. Japanese Patent Application Laid-Open No. 53-5619i 3-inch Publication (Manufacturing power of hydraulic lath V,
5 tsp of water in the by-produced silica disclosed in )
Those who use it after drying it to less than i% / II:
Nucleic crystals are powders that are difficult to handle in the process, not only because of high raw material costs, but also because they cause dusting or flashing of the dried product. Furthermore, when this powder is mixed into a thorium hydroxide solution or a sodium aluminate solution for the production of theolite, there is a problem in that its rapid and uniform dispersion is inhibited by its own physical properties.

a; Furthermore, in connection with the invention of the same issue, a dry product of silica, which is a by-product obtained by drying a water-containing product at a high temperature such that its silanol groups are lost, is further reacted with sodium hydroxide, etc. It is not suitable as a substitute for the by-product silica according to the present invention because it lowers the properties. b, Japanese Patent Application Publication No. 1973-
Prior to the reaction with sodium hydroxide, monoga such as silicate clay and others disclosed in Publication No. 107899 are first mixed with an aqueous sodium hydroxide solution, aged, dissolved, and pulverized. When using the by-product silica according to the present invention, there is no need for any unnecessary extra steps.

c. Fine powder amorphous silica such as commercially available Aerosil (manufactured by Nippon Aerosil Hantao Co., Ltd.), Nibcil (Nippon Silica Stock System) or silica sol; or d. Silica gel or activated silica (obtained by acid treatment of resistant clay): The former two (Note C) are difficult to handle in the process as a powder and in terms of raw material cost, while the latter, activated silica, has similar difficulties, as well as the chemical problems involved in the reaction in the process of producing zeolite. The activity is significantly inferior to that of the by-product silica according to the present invention.

The content of silica in the by-product silica used in the present invention is
A content of 90% by weight or more based on 100°C drying (stellar product) is sufficient and can be preferably used. If the content decreases to 90% by weight, the quality of the desired zeolite product may decrease, and depending on the types of coexisting components, the quality of the filtrate obtained by filtering out the zeolite crystals, which will be described later, may also decrease. As a result, undesirable effects may be brought about when the filtrate is recycled and used in carrying out the method of the present invention. Silica containing a large amount of such undesirable coexisting components, particularly coloring organic substances, is particularly undesirable as a raw material for producing zeolite for detergents.

The morphological quality or solubility of aluminum hydroxide used in the present invention is determined in accordance with the practice of the present invention. When adopting an embodiment in which raw silica is mixed, there are no particular limitations. However, when adopting an embodiment in which the nuclear material is in powder form or the powder material is suspended in a sodium hydroxide solution and mixed with the by-product silica, the powder material is heated at a temperature of 80° to 105°C. It must be able to quickly dissolve in the liquid at a temperature of . Specifically, for example, α-aluminum chloride having a particle size distribution that passes through a water sieve having a mesh size of 44 pm, and which is highly reactive with thorium hydroxide, is used in the form of fine particles. preferable.

In the case of implementing method jE in which aluminum hydroxide is mixed with by-product silica in the form of powder or suspension as in ◎ above, if a material with poor reactivity with thorium hydroxide is used, the zeolite according to the present invention Synthesis reactions require higher temperatures or longer times than normal embodiments of the present invention. In addition, since the by-product silica is extremely easily soluble in the sodium hydroxide solution, the liquid phase of the reaction temporarily becomes silica-rich in composition, making it easy to produce sodalite, which can lead to the formation of sodalite. Product zeolite is also likely to be of inferior quality.

The sodium hydroxide used in the present invention may be fresh each time, but the filtrate obtained by separating zeolite crystals from the synthesis solution after the previous zeolite synthesis according to the present invention (Note, mother liquor and washing liquor) There is no particular problem even if a method is adopted in which only the insufficient amount, that is, the amount taken out of the system as a result of the previous reaction, is replenished, and such an embodiment is economically preferable. The sodium hydroxide is solid and liquid E.
(Note: Sodium hydroxide solution). However, the following impurities that may be contained in the sodium hydroxide are as follows: ◎ Iron content colors the zeolite; In both cases, it is preferable that the amount of impurities in the thorium hydroxide is as low as possible because it reduces the strength.

The water used in the present invention is added to the above-mentioned recycled filtrate, by-product silica, aluminum hydroxide, and additional thorium hydroxide (only that which was brought into the reaction system by f) is added. Such an embodiment is one of the characteristic features of the method of the invention.

As described above, as a result of using water in the above-described manner, the balance of sodium hydroxide and water in the reaction mixture according to the present invention is maintained within the most preferable range, and it is possible to maintain it in this manner. Most economical.

The composition ratio of each component of silica, alumina, soda and water for zeolite synthesis in the present invention is zeolite I.
It is sufficient within the range of known composition ratios to form. To explain this point in more detail, first, regarding the concentration of thorium hydroxide, since the by-product silica according to the present invention has high chemical activity against sodium hydroxide, It is sufficient to have the ability to dissolve the raw material aluminum hydroxide. However, on the other hand, it is well known that a decrease in the concentration of sodium hydroxide used prolongs the crystallization time of zeolite I, and conversely, as the concentration increases, sodalite is more likely to form as a by-product. The same is true for the method.

The preferred concentration of sodium hydroxide has the following relationship with the order of mixing the raw materials according to the present invention.

That is, for #i dilute sodium hydroxide solution,
Aluminum hydroxide is more difficult to dissolve than by-product silica. Therefore, if an embodiment is adopted in which aluminum hydroxide is dissolved in a sodium hydroxide solution in advance, there will be no need to add additional sodium hydroxide to the subsequent dissolution process of by-product silica, and the already produced aluminic acid I
・Only the sulfur and lithium hydroxide remaining in the lithium liquid is sufficient.

The optimum concentration of silica in the production of zeolite is
It is known that it depends on the concentration of alumina in the reaction system.

Also in the case of the present invention, (S+02) / (A1203)
If the molar ratio exceeds 2, sodalite is likely to be produced as described above. The concentration of silica and alumina is also related to the size of the primary particles of the zeolite produced.
The magnitude tends to be larger at low concentrations and smaller at high concentrations.

From the following explanation and experimental facts, it is desirable that the concentration of each component composition applied to the method of the present invention falls within the following range, taking into consideration the quality of Iola II to be produced and the manufacturing cost.

(Na2e) / (A1203) = 1.5 to 3.0
(Molar ratio) (Sin2) / (A1203)
= 1.5~2.1 (tt)8.0 111111--2-X 100 (H20') + (Na20) + (A
IQO3) + (Si02) In the method of the present invention, the desired zeolite can be produced well by any of the following methods (1) to (2) for mixing the various raw materials described above. That is, they: ■ Separately disperse by-product silica and aluminum hydroxide in a sodium hydroxide solution;
(j) mixing the by-product silica after dissolving aluminum hydroxide in the sodium hydroxide solution; and (j) mixing the by-product silica in the sodium hydroxide solution. There is a method of dissolving by-product silica and then mixing aluminum hydroxide, or a method of dissolving both by-product silica and aluminum hydroxide separately and then mixing them. However, when synthesizing zeolite by directly reacting powdered raw materials in a sodium hydroxide solution as in the method of the present invention, the reaction mixture is subjected to severe If stirring is not continued, the zeolite produced tends to form aggregated crystals, and the primary particles also tend to become large. Furthermore, a major reason is thought to be that aluminosilicate-1 precipitates on the surface of the undissolved raw material powder and prevents the dissolution of the raw material, but this precipitation significantly delays or stops the subsequent reaction. There is. In such cases, the X-ray diffraction peak of the produced zeolite is low;
Ion exchange capacity also decreases. Incidentally, the sodium hydroxide solution mentioned here preferably includes the above-mentioned liquid that is recycled and used in the zeolite production reaction, and vigorous stirring refers to the aluminosilicate-1 precipitated on the surface of the undissolved raw material.
The strength of stirring is greater than that which can peel off the material. Therefore, instead of so-called stirring, a method in which the reaction mixture is placed in a ball mill or the like and pulverized and mixed (mill mixing) is also effective.

Based on the above, 1. As in the method of the present invention, by-product silica, which is extremely easily soluble in a sodium hydroxide solution, is used as a silica source to economically produce zeolite of a quality suitable for detergent builders, for example. In this case, the raw material mixing method of (1) above is used, that is, after dissolving aluminum hydroxide in a sodium hydroxide solution, the aluminum hydroxide is dissolved in a wet Wtl raw material solution or a part of the sodium hydroxide solution is used to dissolve the aluminum hydroxide. The most preferable method is to prepare a liquid and then mix it.

Regarding this, an explanation using drawings will be added.

The drawing shows a relationship curve between the dissolution time (hours 9 minutes) of by-product silica in a sodium hydroxide solution and the dissolution rate (C%). 1st,
In Fig. 2, the symbols indicating each curve indicate the determination result (pass or fail) based on the dissolution conditions, that is, the Na2O concentration, the (Si02)/(Na20) molar ratio, and the temperature. This is summarized in the table below.

Table notes, 10 molar ratio, 2. Quality is best O2 good good 2 average O
As is clear from Section 9-1-, it is clear that if appropriate dissolution conditions are selected, good dissolution results for silica can be obtained within a short time. Furthermore, the dissolution rate of by-product silica is significantly higher than that of aluminum hydroxide,
In addition, it is preferable to dissolve aluminum hydroxide in a sodium hydroxide solution under the conditions of using a high-temperature, high-concentration reagent solution, and these facts can also explain why the above-mentioned mixing method (2) is preferable.

Incidentally, in the known production methods of A-type zeolite, both the method of mixing the reaction raw materials as a solution IE and the method of mixing the raw materials in a solid state are heated to a temperature of about 60°C or less. After aging for 1 hour to LEil, the product is kept at a temperature of about 80°C to crystallize. However, in the method of the present invention, there is no need for complicated or delicate temperature control as in the above-mentioned known techniques, and after the reaction path γ of the present invention described above, the zeolite crystallization temperature is set at a known crystallization temperature of zeolite, for example, 80° to 105°. It is sufficient to maintain the reaction mixture at 3°C. In particular, when using the method described above (dissolving aluminum hydroxide in a thorium hydroxide solution using a trowel and then mixing by-product silica with the solution), the method described in the prior art is as follows: Since there is no need for complicated temperature adjustment such as "cooling for crystallization → heating for crystallization", there is also the advantage that there is no loss of thermal energy associated with such adjustment.

Thus, according to the method of the present invention, type A zeolite can be easily produced through a process accompanied by the following two characteristic effects. The first characteristic effect is that the use of by-product silica eliminates the need for special melting and explanation of the raw material silica, and also eliminates the need for the glue formation step performed in known methods.

In other words, in the method of the present invention, the dissolution, reaction and crystallization of aluminum hydroxide and by-product silica can be carried out in the same equipment. The second effect is that since the by-product silica is treated as a hydrated substance, there are no process troubles peculiar to the handling of fine powder, such as dust generation and flashing, which accompany drying of silica in known methods.

The present invention will now be explained in a JL format using examples.

Example I From hydrated by-product silica, aluminum hydroxide, sodium hydroxide and water shown in Table 1 (Na20) / (Al2
O2) = 2.7 (molar ratio), [:5i02) /
(AI'203)-2,0 (molar ratio), H,,0=94
A mixture with a composition of mol % was prepared. 90% of this mixture
The mixture was stirred for 20 hours at 110,000 rpm using a homogenizer while heating to maintain the temperature at .degree. Thereafter, the stirring speed was reduced to 1100 Orp and stirring was continued for 2 hours, and then filtered using No. 5G filter paper and washed with warm water. The physical properties of the obtained solid content are shown in Table-2.

Example II Using the same raw materials as Example I, (Na20) / [
A1,03] (molar ratio) -1,7 (molar ratio) sodium aluminate solution (Na20 = 18.0 weight, %%, A
Iq03 = 17.4m; 1k%) was prepared. This sodium aluminate solution was heated to 90°C, and then thorium hydroxide, water, and hydrated by-product silica were mixed (Na20) / [:Al,,03) = 2.7
(molar ratio), (Si02r-/(A1203)
72.0 (mole ratio), a mixture of H2O=94 mol% was prepared. This mixture was stirred for 30 minutes at 110,000 rpm using a homogenizer while maintaining 90°C.

Thereafter, the stirring speed was reduced to 1100 Orp and stirring was continued for 2 hours, followed by suction filtration using No. 5G filter paper and washing with warm water to obtain zeolite crystals. The physical properties of the obtained solid content are shown in Table-2.

Example ■ A raw material mixture with the same composition was prepared in the same manner as in Example ■,
The mixture was ground in a pot mill for 3 hours while heating to 80°C. The obtained slurry was suctioned and filtered using No. 5G filter paper, and washed with warm water to obtain zeolite crystals. The physical properties of the obtained solid content are shown in Table-2.

Comparative Example 1 Synthesis was carried out in the same manner as in Example (1), and only stirring was performed using a homogenizer using a motor stirrer at 80 Orpm. The physical properties of the solid content are shown in Table 2.

Comparative Example 2 The same synthesis as in Example II was carried out, except that only a homogenizer was used for stirring and a motor stirrer was used at 60 Orpm to produce 11 solids.The physical properties of the solid content are shown in Table 2.

Table-2 Measurement V: 1. Crystal type = X-ray diffraction analysis, 2. Primary particle size: Scanning electron microscopy 3: Average particle size: Light transmission particle size analysis (D50%) 4,
Calcium ion exchange capacity 2100°C dry sample 385
mg to GaCl2: 10-3mar/U, 1
After dispersing in 0100O for 15 minutes, the C in the liquid was filtered.
a is measured by atomic absorption spectrometry, and the temperature is 1000°C.
Ignition range (-: Corrected by value.

[Brief explanation of drawings]

Show the line. I"2 Agent: Patent attorney Katsuhiko Nonaka Surji★3

Claims (1)

[Claims] (+) Hydrous amorphous silica, aluminum hydroxide, sodium hydroxide, and water, which are produced as by-products when synthesizing cryolite or aluminum fluoride using silicofluoride, are their constituents. 4 minutes, Na2O,' Al2O3 and 5i02 and H2O are all molar ratios or mol% (Na20) / (A1203) = 1.5 ~
3.1CS+02) / (Al2O3) = 1.
5 to 2.1 = 90 to 96 mol %, the reaction is carried out under vigorous stirring, and the zeolite is crystallized at normal pressure and 80 to 105°C. (2) A patent claim in which aluminum hydroxide is dissolved in an aqueous sodium hydroxide solution, and hydrated amorphous silica or a suspension of the substance in water or an aqueous sodium hydroxide solution is mixed into the solution obtained by the dissolution. The method described in scope item (1).