RU2033966C1 - Method for production of granulated zeolite of faujasite type based on natural clay materials - Google Patents

Abstract

FIELD: processing of natural materials. SUBSTANCE: natural clay material is mixed with neutral aluminum salt, sodium hydroxide, and introduced at the same time into reaction mixture is aluminum hydroxide or silicon dioxide. Mixture is subjected to steam heat treatment and after subsequent thermal activation, it is mixed with aluminosilicate hydrogel to obtain homogeneous mass. Neutral aluminum salt is used in form of aluminum sulfate. Initial clay material is mixed with neutral aluminum salt and sodium hydroxide in mass ratio of 100:0.05:0.02, respectively and steam heat treatment is carried out at 100-250 C for 10-60 min. EFFECT: higher efficiency. 4 cl, 3 tbl

Description

 The alleged invention relates to the processing of natural materials, in particular to the production of granular synthetic zeolite type faujasite, which can be used in the chemical, oil, oil refining, gas industry, as well as for the purification of water and gas streams from cations of heavy metals and organic components.

 Closest to the technological essence of the proposed method is the "Method of obtaining zeolite type A", in which the zeolite is obtained by mixing clay material with aluminum hydroxide, calcining, molding, drying granules, hydrothermal crystallization (see ed. Certificate of the USSR N 1432005, 1988 ) The disadvantages of this method include: low dynamic activity of the granules of the adsorbent; low degree of crystallization of the product.

 The objective of the invention is: the use of a wide range of clays, which significantly expands the raw material base in the production of granular zeolites (the transition from the possibility of using kaolin to the use of clays of other geomorphological types and other chemical composition) and increasing the absorption rate (dynamic activity) of zeolite granules of n-heptane vapor, compared with the dynamic activity of faujasite obtained by the method of the prototype.

To do this, the initial clay (the chemical compositions of the initial clay materials and intermediate reaction masses are presented in Table 1) are mixed with a medium aluminum salt, caustic soda, aluminum hydroxide or silicon oxide, depending on the type of source clay, subjected to thermocouple treatment and after subsequent thermal activation are mixed with aluminosilicon hydrogel until a homogeneous mass is formed, while aluminum sulfate is used as the average aluminum salt, a mixture of the initial clay material with the average aluminum salt with mix with caustic soda in a mass ratio of 100: 0.05: 0.02, respectively, and thermocouple treatment is carried out at a temperature of 110-250 ^about C for 10-60 minutes

Distinctive features of the claimed method in relation to the prototype are:
the aluminosilicate feedstock is mixed with a medium aluminum salt, sodium hydroxide, aluminum hydroxide. In the case of using halloysite clay (example 2) to obtain the necessary chemical composition, silicon dioxide is added to the initial clay;
the aluminosilicate mass is subjected to heat treatment with water vapor to increase its chemical activity;
after thermal activation, the aluminosilicate mass is mixed with alkaline aluminosilicon hydrogel, which is necessary for the optimal chemical composition and porous structure of the aluminosilicate mass, suitable for granulation into X-ray amorphous granules and their further hydrothermal crystallization into zeolite.

 The method is implemented as follows. Natural clay material is distilled from impurities of pebbles, sand, crushed to a particle size of not more than 20 microns and subjected to acid purification. The resulting mass is mixed with a medium aluminum salt, for example, aluminum sulfate. To this mass add caustic soda in an amount of from 0.02 to 0.05 wt. The introduction of caustic soda into the clay mixture makes it possible to obtain a chemically active structure during subsequent thermocouple treatment. The introduction of caustic soda in an amount of less than 0.02 wt. It turns out to be insufficient for the formation of a chemically active mass structure, an increase in the amount of caustic soda over 0.05 wt. does not increase the degree of conversion of the original clay material into active layered structures. These additives to natural clay material make it possible to start the process of kaolinization of the structure of this aluminosilicate during exposure to water vapor and subsequent calcination. Thermal processes in a water vapor medium alter the structure of the initial clay material in such a way that it becomes possible to process zeolite structures of various types during their further processing, the basis of which are aluminum-silicon oxygen tetrahedra, articulated in a special way.

 The kaolinization of the structure of clay materials leads to the predominant formation of layered structures. Subsequent thermal activation in the presence of a stoichiometric amount of aluminum hydroxide leads to the formation of aluminosilicates, in which aluminum atoms from the octahedral environment become tetrahedral. It should be noted that in addition to aluminum hydroxide, silicon dioxide can be introduced into the reaction mass in a stoichiometric ratio to the composition of the initial clay. In this case, at the time of thermal amorphization, a solid-phase reaction of the formation of an aluminosilicate of intermediate composition occurs.

 The destruction of the crystal structure of the reaction mass during thermal activation, its amorphization significantly increases the chemical activity of the calcined reaction mixture, makes it capable of entering into solid-phase reactions proceeding in parallel with amorphization, and forming reactive compounds with aluminum hydroxide or silicon dioxide, and then interacting with alumina-silica hydrogel with the formation of alkaline reaction masses that are able to crystallize in a crystallization solution in Literature type faujasite.

Introduced into the reaction mass of aluminum hydroxide or silicon dioxide can be obtained in various ways. This can be industrially obtained in significant quantities from alumina production waste, or it is aluminum hydroxide obtained by filtering a suspension obtained by mixing solutions of aluminum salt and sodium aluminate, or obtained by mixing solutions of aluminum salt and caustic soda. Silicon dioxide can be obtained by exposure to a solution of sodium silicate of ammonium nitrate, solutions of sulfuric or nitric acid. This can be a departure from the production of phosphate fertilizers white soot, or specially produced highly dispersed silicon oxide, the so-called aerosil, or it can be a waste from the metallurgical production of ferrosilicon siliceous dust, highly dispersed SiO ₂ powder in a chemically active form.

The mass obtained after adding aluminum hydroxide or silicon dioxide is subjected to thermocouple treatment, which allows you to get the desired structure of the intermediate reaction mass at a minimum temperature of 110 ^about ; temperature decrease below this level stops flowing solid phase reaction structure change when the temperature rises above 250 ^{° C} side reactions begin to dominate, leading to the formation of intermediate compounds that are not transformed during further processing in the zeolitic molecular sieve. The necessary degree of conversion of the clay mass during thermocouple processing occurs within 10-60 minutes The increase in the duration of stay in the medium of water vapor in excess of the specified time does not lead to an increase in the degree of conversion.

 The next step in the preparation of zeolite adsorbents is the thermal activation (amorphization of structures) of the resulting kaolin-like clay structures. This technique is well known and widely used in industry in the preparation of catalysts and adsorbents.

 The next step is the mixing of the intermediate clay mass with alkaline aluminosilicon hydrogel. This mixing allows to obtain a plastic mass, which is subjected to an extrusion process on modern industrial granulators. The method of mixing clay mass with aluminosilicon hydrogel makes it possible to obtain a porous structure of such a degree of permeability that polycrystalline zeolite aggregates in the form of granules form during further hydrothermal crystallization. The secondary porous structure of these granules in comparison with the porosity of zeolite granules obtained by the prototype method, can significantly increase the absorption rate and the equilibrium adsorption capacity of the adsorbed components, which is a production indicator characterizing the quality of the adsorbent. It should be noted that the composition of the prepared alkaline aluminosilicon hydrogel, obtained by mixing solutions of sodium silicate and sodium aluminate, is selected so that when mixed with a clay mass, a plastic non-crumbling mass is obtained, which after granulation allows to obtain amorphous granules crystallized into zeolite with a high degree of permeability and phase purity.

 Amorphous granules obtained as a result of the above operations must satisfy two main requirements: in terms of chemical composition, they must be in the optimal region of the zeolite crystallization field; be strong and have an optimal porous structure.

 To obtain a zeolite of the indicated type, the initial granules of which are made from clays of different types, the composition of the crystallization solution will also be different. The composition of crystallization solutions will necessarily include sodium hydroxide solution and mother liquor from previous crystallizations (this allows for almost complete utilization of alkaline effluents) and sodium aluminate solution. During crystallization of a faujasite-type zeolite based on all types of clays, a crystallization solution is used, which includes sodium hydroxide solution and sodium aluminate solution. In detail, the essence of the proposed method is illustrated by specific examples of its implementation.

PRI me R 1. In this example, the possibility of obtaining zeolite X from bentonite clay by mixing it with aluminum sulfate, sodium hydroxide, aluminum hydroxide, which is a waste of alumina production. One ton of clay is mixed in a mixer for bulk materials with 0.850 kg of aluminum sulfate for 40 minutes and then with 0.500 kg of caustic soda for another 20 minutes. To this mass, 177.8 kg of aluminum hydroxide, which is a by-product of the production of alumina, is added with stirring. The resulting mass is treated with water vapor at 170 ^about C for 50 minutes After thermocouple treatment, this mass is subjected to thermal activation (calcination) at 720 ^о С for 3 hours.

 The resulting 1116.5 kg of the mixture in a mixer for pasty materials is mixed with 702 l of alkaline aluminosilicon hydrogel obtained by mixing 454 l of sodium silicate and 247.9 l of a solution of sodium aluminate. The concentration of silicon oxide in a solution of sodium silicate is equal to 270 g / l, for sodium oxide 93 g / l. In a solution of sodium aluminate, the concentration of aluminum oxide is 280 g / l, sodium oxide 253.6 g / l. This mass is mixed for 50 minutes in a mixer and then granulated into granules.

After drying, granules in an amount of 1410 kg are loaded into a crystallizer, where a crystallization solution is also poured. The crystallization solution is obtained by mixing 3090 liters of water, 981 liters of sodium hydroxide and 76.9 liters of sodium aluminate solution. The resulting reaction mass is maintained at ³⁰ ° C for 16 hours, then the temperature is raised to ^{90 °} C and the mass is subjected to the hydrothermal crystallization process further 24 hours. The resulting zeolite is washed from alkaline mother liquor, dried.

 The parameters of the zeolite obtained in this example are shown in table.3.

 PRI me R 2. This example shows the possibility of obtaining type X zeolite based on halloysite clay when mixed with aluminum nitrate, sodium hydroxide and silica, which was obtained by filtering a suspension that was formed by mixing a solution of sodium silicate and solution ammonium nitrate.

 This example shows the possibility of using one stripped off mother liquor from previous crystallizations in order to partially replace the crystallization solution.

 After a pretreatment, one ton of halloysite clay is mixed with 0.48 kg of aluminum sulphate and 0.3 kg of sodium hydroxide in a mixer for bulk materials for a time sufficient to evenly distribute the components.

After that, 194.4 kg of silicon oxide is added to the mass, which is obtained by filtering a suspension of silica obtained by pouring 720 l of a solution of sodium silicate and 960 l of a solution of ammonium nitrate having a concentration of 180 g / l in NH ₄ NO ₃ . After intensive mixing of all components of a given mass is treated with water vapor at 190 ^{° C} for 60 min. After processing termoparovoy this mass was calcined at 720 ^{° C} for 3 hours.

 The resulting 1195.23 kg of the intermediate reaction mixture is mixed in a paste-type mixer with 810 L of aluminosilicon hydrogel, which is obtained by mixing 551.7 L of sodium silicate solution and 258.2 L of sodium aluminate solution.

 After a plastic mass suitable for granulation is formed in the mixer, it is granulated into granules. After drying, granules in the amount of 1532.5 kg are loaded into the crystallizer and must be filled with a crystallization solution, which is obtained by draining 3810 liters of water, 1036 liters of caustic soda and 144 liters of sodium aluminate solution.

In order to reduce the reagent consumption and utilize the mother liquor from crystallization, this crystallization solution was replaced by a mixture consisting of 294 m ³ sodium hydroxide solution, 144 l sodium aluminate solution and 4.55 m ^{3 one} stripped off mother liquor from the previous crystallization (decrease in mother liquor volume as a result of evaporation is 1.0967 times). The temperature and time crystallization conditions are the same as in Example 1. After crystallization, the zeolite is washed from the alkaline mother liquor and dried.

 Physico-chemical parameters are given in table.3.

 PRI me R 3. The present example shows the possibility of synthesis of faujasite from lake-river clays by mixing them with ammonium sulfate, sodium hydroxide and ammonium hydroxide.

One ton of lake-river clay after preliminary processing in a mixer for bulk materials with 0.96 kg of ammonium sulfate and 0.5 kg of caustic soda is mixed until completely homogeneous, 185.2 kg of aluminum hydroxide obtained by filtering the suspension formed when mixing 422 l of a solution of aluminum sulfate and 289.8 l of a solution of sodium aluminate. After these components by mixing uniformly distributed over the volume of the intermediate mass, it is subjected to treatment in water vapor atmosphere at 205 ^{° C} for 55 min. After thermocouple treatment, this mass is subjected to thermal amorphization according to the regime described in example 2.

 The resulting 1122.5 kg of this treated mass is mixed with 895 l of alkaline aluminosilicon hydrogel, which is formed with vigorous stirring of 605.1 l of sodium silicate solution and 289.9 l of sodium aluminate solution. After mixing the powder mass with an alkaline aluminosilicon hydrogel, a plastic mass forms, which is granulated into granules. 1495.9 kg of granules are loaded into a crystallizer, poured with a crystallization solution and kept under hydrothermal conditions similar to that in Example 1.

 The crystallization solution is prepared by mixing 4270 liters of water with 896 liters of sodium hydroxide solution and 118.4 liters of sodium aluminate solution.

 After the crystallization process is completed, the zeolite is washed from an alkaline solution, dried.

 Physico-chemical parameters of the zeolite are given in table.3.

Claims (3)

1. A METHOD FOR PRODUCING A GRANULATED ZEOLITE OF TYPE FOGAZIT ON THE BASIS OF NATURAL CLAY MATERIAL, including mixing clay material with an oxygen-containing inorganic substance, calcining, granulating, drying granules, hydrothermal crystallization in an alkaline solution, which does not contain oxygen, or an organohydrogen dioxide that does not contain aluminum hydroxide silicon, the mixing is additionally served with an average aluminum salt and sodium hydroxide, taken in an amount of 0.02 0.05 wt. of the amount of clay material, after mixing, thermocouple treatment of the mixture is carried out at 110-250 ^° C for 10-60 minutes, before granulation, it is mixed with aluminosilicon hydrogel until a homogeneous mass is formed and hydrothermal crystallization is carried out in a solution containing aluminate ions.  2. The method according to claim 1, characterized in that aluminum sulfate is used as the average aluminum salt.  3. The method according to claim 1, characterized in that the mixing of clay material with an average aluminum salt and sodium hydroxide is carried out in the following mass ratio of components 100 0.05 0.02, respectively.

Images