RU2448902C1 - Method of making solid hydrosilicate gel - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to making solid gels based on complex mixtures of hydrosilicates of alkali metals. Porous silica material, which contains not less than 70 wt % amorphous SiO₂ is crushed until silica sand is obtained. The sand and the air-dried granular caustic alkali are then fed into a reactor having a switched on mixer and then stirred until a hot viscous semi-finished product is obtained. The semi-finished product is loaded into containers and held therein with gradual natural cooling to ambient temperature until a mature solid hydrosilicate gel is obtained.

EFFECT: simple equipment used in the process and less need for external heat sources.

7 cl, 4 tbl

Description

Technical field

The invention relates to the manufacture of solid gels based on complex mixtures of alkali metal hydrosilicates, which are obtained by treatment with caustic alkali of suitable raw materials containing amorphous silicon dioxide.

Such gels can usually be used:

a) after crushing and dilution with water to the required viscosity - as mineral adhesives or components of organomineral adhesives for the manufacture of a variety of practically non-combustible composite materials;

b) after granulation and drying - as raw materials for the manufacture by heating and swelling of heat-insulating filling materials, the basis of artificial soil for growing plants and highly porous aggregates of lightweight concrete;

c) after fine grinding of granules into powder (mainly with an average particle size of 20 to 100 microns) - as accelerators for setting cement compositions, raw materials for the formation of fire-resistant coatings on the details of buildings and engineering structures, and fillers of polymer compositions.

State of the art

Gel-like hydrosilicate materials have been known for so long that information about them and the basic processes for their manufacture are already included in the directories.

For example, the well-known "liquid glass" (Brief chemical encyclopedia. - M .: Publishing house "Soviet Encyclopedia", t.4, 1965, p.1037-1038).

It is based on solid "soluble glass", which is a mixture of alkali metal hydrosilicates of the general formula R ₂ O · mSiO ₂ , where R ₂ O is sodium and / or potassium oxide, and the silicate module (number m) is usually from 2.0 up to 4.5.

Solid soluble glass is obtained by melting at 1100-1400 ° C a mixture of silica sand, the basis of which is crystalline SiO ₂ , with soda and / or sodium sulfate. During melting, SiO ₂ passes into an amorphous state, which is fixed during the formation of these silicates. The product has the form of a silicate block if the melt was cooled in bulk, or silicate granulate if the melt was quickly cooled in running water and cracked into grains. Liquid glass is obtained by grinding solid soluble glass and mixing it with water.

It is clear that the high-temperature process for producing solid soluble glass as the basis of liquid glass is not energetically favorable.

Therefore, liquid glass is often made from raw materials based on amorphous SiO ₂ . It is treated in autoclaves at a temperature of about 200 ° C with caustic alkali solutions with the direct preparation of a colloidal solution of sodium hydrosilicates (see the above article in the “brief chemical encyclopedia”).

A decrease in the processing temperature, characteristic of a “wet” process, significantly reduces energy costs and reduces the cost of liquid glass.

Unfortunately, the solubility of alkali metal hydrosilicates in water is reduced if, in addition to amorphous SiO ₂ , impurities of other metal oxides are present in the feed, for example, 1.0-1.35% Al ₂ O ₃ + Fe ₂ O ₃ and 0.4-0, 6% CaO (GV Kukolev “Silicon chemistry and physical chemistry of silicates.” - M.: Higher School Publishing House, 1966, p.164).

Therefore, the basis for the "wet" production of liquid glass are rare deposits of siliceous raw materials, which contain more than 98.0% of amorphous SiO ₂ .

In addition, composite materials based on liquid glass are hygroscopic and therefore unstable in a humid environment, and in a dry gas environment they crack more easily, the lower the concentration of reinforcing aggregates in them.

Further, liquid glass-based cement slurries, widely used in municipal services for plugging water breakthroughs and filling gaps, have an extremely small viability of several minutes.

And finally, water in liquid glass serves only as a dispersion medium, is easily removed from it during drying and therefore does not affect the fire resistance of glued products.

Therefore, the development of simple and economical methods for the manufacture of more advanced hydrosilicate gels from raw materials with a relatively low concentration of amorphous SiO ₂ remains an urgent problem.

A number of steps towards its solution have already been taken.

So, in DA Patent No. 3802 describes a method of manufacturing a hydrosilicate gel, including grinding a siliceous feed, which contains at least 85% amorphous SiO ₂ , into a fine-grained mass and treating this mass with caustic soda in a medium of saturated water vapor at a temperature of 80-100 ° C in within 20-60 minutes

The product of this method, which is calculated per 100 mass parts (hereinafter, parts by weight) of amorphous SiO _2, contains 1-30 parts by weight of alkali metal hydroxide and 30-125 mph water, insensitive to ballast impurities. It has the appearance of a sticky mass and is capable of melting once, and when heated above 200 ° C, it hardens irreversibly.

The specific energy consumption for the manufacture of such a gel is noticeably lower than for the production of liquid glass by the wet method.

However, caustic soda, that is, a concentrated (normally 48%) aqueous solution of caustic soda, requires careful handling not only for the safety of work, but also to protect it from contact with air and from overcooling.

Indeed, air always contains CO ₂ , which is readily soluble in water and able to react with sodium hydroxide to form inactive NaHCO ₃ . Therefore, for long-term storage of caustic soda, hermetic tanks equipped with means for forming a nitrogen pad over the solution mirror are needed.

Further, at a temperature below + 7 ° C, caustic soda acquires a jelly-like consistency, and a dense precipitate of NaOH forms at the bottom of the tank. Such raw materials are practically unsuitable for pumping. Therefore, the tanks have to be equipped with thermal insulation, heaters and mixing means.

The specialist understands that the above applies to potassium hydroxide and that the use of expensive and complex equipment for working with liquid caustic alkalis significantly complicates and increases the cost of implementing the known method.

Moreover, the stickiness and viscosity of the hydrosilicate gel obtained by the described method vary widely.

A method of manufacturing a more stable solid hydrosilicate gel is known from international publication WO 97/33843 of 09/18/1997. This method includes:

crushing the selected porous silica raw material containing at least 70% by weight of amorphous SiO ₂ to obtain particles with a size of 1.0-2.5 mm,

mixing these particles with an aqueous solution of caustic alkali,

steaming the mixture (saturated water vapor, if the specified raw material was only partially watered during the preparation of the mixture, or by heating the completely watered mixture from an external heat source until it is saturated with water vapor) at atmospheric pressure, a temperature of 75-90 ° С and stirring until hydrosilicates are formed and

cooling the steamed mixture to room temperature (18-25 ° C) for a time sufficient for it to transition to a brittle hydrosilicate gel state.

This solid gel when heated above 100 ° C becomes plastic, and at temperatures above 200 ° C it intensely swells and hardens irreversibly.

After crushing and grading according to particle size distribution, a brittle gel is suitable for processing into two types of heat-insulating materials, namely:

into expanded granules, which are obtained by heating the initial granules in a free state at a temperature of from 200 to 250 ° C for 25-35 min (for using products as bulk insulation or aggregates of light concrete),

into blocks or slabs, which are obtained by swelling the mass of adhered granules at a temperature of from 250 to 450 ° C for 2.5-6.0 hours.

However, the method described above also requires the use of complex and expensive means of storing caustic soda.

In addition, the solid hydrosilicate gel obtained in this way is of little use as an astringent and, especially, as an adhesive, since the introduction of fillers into a highly viscous mass and the homogenization of mixtures are difficult. This drawback was especially acute in attempts to create mechanically durable fire-resistant composite materials to protect wood, metal and other building structures from fires.

Further experimental studies showed that it is possible to enhance the adhesive activity and technological properties of solid hydrosilicate gels.

So, from the international publication WO 00/46277 of 08/10/2000, a method for manufacturing a solid hydrosilicate body is known, which is closest in technical essence to the method proposed below. The known method includes:

crushing of porous natural silica raw materials containing at least 70% by weight of amorphous SiO ₂ to obtain the mass of particles, of which not more than 15% have a diameter of more than 10 mm,

dosing the specified raw materials and an aqueous solution of caustic alkali,

preheating an aqueous solution of caustic alkali to a temperature close to the boiling point of water,

mixing siliceous raw materials with a heated solution of caustic alkali,

homogenization of the reaction mixture to distribute saturated water vapor in its entire volume and

immediate unloading of the mixture after its transition to a viscoelastic state.

In this way, a solid gel is obtained which contains a mixture of alkali metal hydrosilicates and from 30 to 40% by weight of bound water, and the ratio of the masses of “dispersed” and “hydrated” water is from 5: 3 to 4: 1. Such a gel is a hydrosilicate "thermoset", which

after grinding, it is suitable for dilution with water,

able to once go into a viscous-fluid state with short-term heating in the temperature range 45-250 ° C and

irreversibly hardens upon prolonged heating to a temperature of more than 180 ° C with the destruction of hydrates, preliminary expansion with melting of the surface layer and final expansion.

This solid gel is especially effective as a fire retardant material (including in the form of compositions that are conveniently prepared from aqueous dispersions of hydrosilicates), which can be explained as follows.

The exothermic effect of alkalization of amorphous SiO ₂ in the particles of crushed raw materials under the action of a hot solution of caustic alkali provides almost uniform heating of the entire reaction mass even with minimal stirring. Ballast impurities in silica raw materials contribute to the homogenization of the mixture, because they adsorb a portion of the sodium ions. The cooling of the viscoelastic prefabricated product after unloading ensures the binding of almost all the available water in the solid hydrogel and stretches the alkalization in time until the first contact of the flame retardant material based on the hydrogel with the flame. Removing bound water from a hydrogel requires significant heat. Therefore, the surface temperature of the protected product during fire tests remains at about 100 ° C, the longer, the thicker the layer of fire-retardant material.

Unfortunately, this method of manufacturing a hydrosilicate gel, which is the closest in technical essence to the method proposed below, also requires complex and expensive hardware design, which is due to the use of liquid caustic alkalis and their heating before mixing with silica raw materials.

Summary of the invention

The basis of the invention is the task of changing the order and conditions of preparation of the reagents and alkalization of siliceous raw materials to create a significantly simpler and more economical method of manufacturing a hydrosilicate gel.

The problem is solved in that the proposed method includes:

grinding porous silica raw materials containing at least 70% by weight of amorphous SiO ₂ to obtain siliceous “sand”,

dosing of this “sand” and air-dried granular caustic alkali,

loading them into the reactor with the stirrer turned on and mixing, accompanied by self-heating, to obtain a hot viscous cake mix,

unloading hot viscous semi-finished product in containers and

holding this semi-finished product in containers with gradual free cooling to a temperature close to ambient temperature until a mature solid hydrosilicate gel is obtained.

The use of dry caustic alkali significantly simplifies the hardware design of the process and dramatically reduces the need for external heat sources. Indeed, dry caustic soda or dry potassium hydroxide in the form of granules or flakes can be stored in sealed bags and introduced into the process by opening the bags immediately before loading the alkali into the reactor, and two exothermic reactions simultaneously provide self-heating of the reaction mixture, namely:

dissolving dry alkali in the water present in the siliceous “sand”, and

alkalization of amorphous silicon dioxide in the mass of "grains of sand".

An additional difference is that the raw materials are crushed into “sand” with a particle size of not more than 0.5 mm, which facilitates the alkalization of amorphous SiO ₂ .

The following additional difference is that the moisture content of the siliceous feed is normalized. To do this, excessively wet siliceous “sand” is dried at a temperature not exceeding 100 ° C before being loaded into the reactor, and dry siliceous “sand” is moistened, as a rule, by supplying water with a temperature of 80 to 95 ° C directly to the reactor with the mixer turned on. These measures stabilize the quality of the product.

Another additional difference is that the solid hydrosilicate gel is crushed into granules from 20 μm to 5.00 mm in size and these granules are dried at a temperature below 150 ° C until they lose their ability to stick together. Typically, the granules are dried in a fluidized bed in a stream of air at a temperature of from 110 to 120 ° C. This allows you to store the target product indefinitely and expand its scope.

The best examples of carrying out the invention

Further, the invention is illustrated by a detailed description of the types of raw materials, a method of manufacturing a hydrosilicate gel according to the invention and the results of studies of the obtained products.

Public raw materials for the preparation of a hydrosilicate gel can be natural or man-made minerals containing at least 70% amorphous SiO ₂ .

Natural siliceous minerals are usually selected from the group consisting of sedimentary rocks that are close in chemical composition, such as tripoli, diatomites, flasks, spongolites, and radiolarites (see Ivanenko V.N. Building materials and products from siliceous rocks. - Kiev: "BUDYVELNIK" 1978, p. 5).

Data on natural raw materials of this kind in Ukraine are shown in table 1.

Table 1 CHARACTERISTICS OF NATURAL SILICA RAW MATERIALS Type of raw material and its source TRIPEL Konoplyanskogo deposits, Kirovograd region SPONGOLIT of the Balka wet field, Donetsk region TRIPEL of the Vokzalnaya Gora deposit, Vinnytsia region Quality indicators AVERAGE CHEMICAL COMPOSITION OF DRY MINERAL,% BY MASS amorphous SiO ₂ 82.10 82.34 90.61 alumina Al ₂ About ₃ 5.90 7.67 0.08 iron oxide Fe ₂ O ₃ 3.04 2.84 3.99 calcium oxide CaO 2,30 1.25 1.14 magnesium oxide MqO 0.65 0.74 0.88 sulfur (in terms of SO ₃ ) 0.06 0.23 0.33 organic impurities (p.p.p.) 5.70 3.72 2.76 CAREER HUMIDITY (PER CENT OF THE MASS OF DRY RAW MATERIALS) 35 5 28 MECHANICAL IMPURITIES OF UNCERTAIN COMPOSITION no more than 15 no more than 5 no more than 20

In particular, tripoli of the Konoplyanskoye field was used to experimentally verify the feasibility and effectiveness of the invention.

As technogenic siliceous raw materials containing at least 70% amorphous SiO ₂ , ferroalloy production wastes (microsilica) are used, namely, sludge from gas treatment plants of ferrosilicon production, which are usually stored in dumps polluting the environment.

In particular, for experimental verification of the feasibility and effectiveness of the invention, waste from the Stakhanov Ferroalloy Plant (Ukraine) was used. Their composition and some other data are shown in table 2.

table 2 CHARACTERISTICS OF TECHNOGENIC SILICA RAW MATERIALS CONTENT,% BY MASS, CALCULATED ON DRY RAW MATERIAL amorphous SiO ₂ 89.90 alumina Al ₂ About ₃ 0.96 iron oxide Fe ₂ O ₃ 1.51 calcium oxide CaO 0.73 magnesium oxide MgO 1.25 sodium oxide Na ₂ O 0.68 potassium oxide K ₂ O 0.97 chlorine ions 0,035 bonded carbon 1.10 sulfur (in terms of S ₂ O ₃ ) 0.99 organic impurities (p.p.p., i.e. loss on ignition) 2,55 the average humidity in the plant,% by weight 32.8 bulk density, kg / m ³ 650 ± 50

The proposed method is as follows. At the first stage, a porous silica raw material containing at least 70% by weight of amorphous SiO ₂ (in particular, said tripoli or said ferroalloy waste) is crushed, for example, on a jaw crusher and then crushed to siliceous “sand”.

It is desirable that the average size of "grains of sand" does not exceed 0.5 mm.

A carryover stock of siliceous “sand” is stored in a suitable metal or polymer container.

To obtain a hydrosilicate gel, a thermally insulated reactor with a stirrer is used, equipped with silica sand and heated water dispensers and a manhole for loading dry caustic alkali. In addition, the reactor can be equipped with an adjustable heater (for example, in the form of a water jacket), which will allow it to be operated efficiently even in the cold season, and with temperature control.

It is well known that dry caustic soda and dry potassium hydroxide are supplied to the market in the form of granules or flakes, which are packed in sealed bags of 25 kg. Therefore, it is advisable to open these bags immediately before loading the alkali into the mixer. It is also advisable to pre-set the amount of loaded silica “sand” based on the mass of dry alkali, a multiple of 25 kg

Usually, the actual humidity of each batch of siliceous “sand” is determined before submission for processing. If the humidity significantly (by more than 5-10%) deviates from the preferred value of 40%, then it is normalized by drying excessively wet or by moisturizing dry siliceous “sand”.

In this case, excessively wet siliceous “sand” is pre-dried (before being fed to the reactor) at a temperature not exceeding 100 ° C in a suitable dryer.

Siliceous “sand” and dry caustic alkali are dosed and fed into the specified reactor with the stirrer switched on.

The specific consumption of dry caustic alkali is determined experimentally for each batch of silica raw materials.

As shown below, per 100 kg of siliceous “sand” usually spend from 5 to 20 kg of dry caustic soda and from 10 to 20 kg of dry caustic potassium.

If the moisture content of siliceous “sand” is insufficient, then after mechanical homogenization of the mixture of solid reagents, the required amount of water is heated into the specified reactor with stirring, heated to a temperature in the range from 80 to 95 ° C.

Further mixing of the reaction mixture is accompanied by self-heating due to the above exothermic effects of dry alkali hydration reactions and alkalization of amorphous silica. The temperature of the reaction mixture should be in the range of 75-95 ° C. If it is below 75 ° C (which is usually observed in winter), then the reaction mixture is additionally heated.

The process is carried out to obtain a hot viscous cake mix.

The completion of the process is easily determined by a sharp increase in the power consumed by the stirrer drive (in particular, by the readings of the ammeter).

Then the hot viscous semi-finished product is immediately unloaded into suitable open containers and kept there until a temperature close to ambient temperature is reached, and then until a mature solid hydrosilicate gel is obtained. The maturity of the solid hydrosilicate gel is determined by:

either by its ability to crumble when squeezed,

either by the rebound of the percussion instrument (in particular, the hammer) from the surface of the gel block located in the container,

or by a characteristic non-uniform “cheese” fracture, which 10-20 minutes after breaking off a piece from the block gains shine due to mechanochemical violation of the structure of hydrosilicates and the release of chemically unbound water.

Mature hydrosilicate gel can be an independent commercial product, which, after crushing and diluting with water to the required viscosity, is used as a mineral adhesive or a component of organomineral adhesives.

However, it is preferable to process the mature hydrosilicate gel into a granular material that does not stick during storage and transportation.

For this, a mature gel is unloaded from containers and crushed first into small gravel (for example, in a multi-shaft shredder with a gap between the plates of about 3 cm) and then into granules (for example, in a rotary crusher). In this case, a polydisperse mixture of particles is formed, the size of which, as a rule, is in the range from 20 μm to 5.00 mm.

The granules are immediately fed into the gaseous coolant stream and dried at a temperature below 150 ° C until the ability to stick together is lost. This temperature threshold is lower than the temperature of thermal destruction of crystalline hydrates (160-170 ° С). Preferred drying of the granules in a fluidized bed in the temperature range from 110 to 120 ° C.

Granules are removed from the dryer when their surface becomes dull, which serves as a sign of the removal of free water and the closure of chemical bonds in hydrosilicates.

Dried granules are usually forced to cool to ambient temperature, classified according to particle size distribution and packaged in a suitable sealed container to avoid contact with drip moisture during prolonged storage and transportation.

Fine fractions of the obtained granules (especially finely divided powder with a particle size of from 20 to 100 microns, which contains from 15 to 25% crystalline hydrated water), it is advisable to use as mineral glue. Indeed, at a temperature of 160-170 ° C, water is released from crystalline hydrates and partially dissolves sodium or potassium hydrosilicates. Thus, for some time, the material is in a liquid state and has increased adhesion, especially to hot surfaces.

Granules with a particle size of more than 1.0 mm, it is advisable to process by additional heating to a temperature in the range from 200 to 500 ° C (usually in a fluidized bed of a gaseous coolant). It has been experimentally established that from one ton of granular solid hydrosilicate gel, up to 12 m ^{3 of} expanded granules can be obtained, which are usually used as bulk waterproof heat-insulating material, a component of artificial soil for growing plants or highly porous aggregate, for example, light concrete and products from them.

To test the feasibility of the described method and assess the quality of the products obtained, two series of experiments were carried out using natural and man-made raw materials, which were the aforementioned tripoli and ferroalloy production wastes with different initial humidity. During the experiments were determined:

specific consumption of dry caustic alkali (kg / 100 kg of siliceous "sand"),

the possibility of obtaining the target product in the form of a solid hydrosilicate gel as such with a specific specific consumption of dry caustic alkali and

bulk density of expanded granules obtained from such a gel (with an average size of such granules from 3 to 8 mm).

The most illustrative examples selected from each of the aforementioned series of experiments on the basis of the proximity of the initial moisture content of siliceous “sand” to its value in the source of siliceous raw materials are shown in table 3.

Table 3 DATA ON THE POSSIBILITY OF OBJECTIVES OF THE PURPOSE PRODUCT IN THE FORM OF BLOCKS OF SOLID HYDRO SILICATE GEL, PRODUCED FROM NATURAL AND TECHNOGENIC RAW MATERIALS, AND ON THE BULK DENSITY OF THE EXPLOSED GRANULATED HYDROGEN Specific consumption of caustic alkali, kg / 100 kg of siliceous “sand” Sample Numbers one 2 3 four 5 Tripoli with initial humidity,% Ferroalloy production waste with initial humidity,% thirty 40 twenty thirty 40 Data on the possibility of obtaining the target product in the form of blocks of solid hydrosilicate gel and the bulk density of expanded granules, kg / m ³ Dry caustic soda 5 - - Solid gel does not swell 180 10 - 220 128 86 fifteen 110 90 205 80 55 twenty - 60 150 68 Solid gel does not form Dry potassium hydroxide 5 - - - - Solid gel does not form 10 Solid gel does not form Solid gel does not form - 185 149 fifteen 240 179 - 163 117 twenty 165 Solid gel does not form - 140 -

From table 3 it is seen that:

specific consumption of 5 to 20 kg of dry caustic soda and 10 to 20 kg of dry caustic potassium per 100 kg of siliceous “sand” in most cases is sufficient to obtain the target product in the form of blocks of solid hydrosilicate gel from natural and technogenic silica raw materials;

the specific consumption of any dry caustic alkali at a level of about 15 kg / 100 kg allows you to get a solid hydrosilicate gel, not only in the form of blocks, but also in the form of dry granules from any siliceous raw materials with different initial humidity;

the increase in the specific consumption of dry caustic alkali allows to reduce the bulk density of expanded granules and thereby reduce the specific consumption of the target product for the production of heat-insulating materials and their thermal conductivity;

Dry caustic soda is suitable for the production of solid hydrosilicate gel from silica raw materials of any origin, and dry potassium hydroxide is preferably used in the processing of technogenic silica raw materials.

An additional criterion for assessing the quality of granules is their water resistance, that is, the ability to be in water for a long time without a noticeable loss of strength.

To this end, the expanded granules were kept for two weeks in water at room temperature and the relative water resistance was evaluated on a five-point scale, in which a zero rating corresponded to the preservation of the initial compressive strength, and five points indicated a softening. The results of such tests are shown in table 4, in which the numbers of examples and the bulk density of expanded granules correspond to what was indicated in table 3.

Table 4 DATA ON RELATIVE WATER RESISTANCE OF EXPLOSED GRANULES OBTAINED FROM DRY GRANULATED SOLID HYDRO SILICATE GEL Specific consumption of caustic alkali, kg / 100 kg of siliceous “sand” Sample Numbers one 2 3 four 5 Tripoli with initial humidity,% Ferroalloy production waste with initial humidity,% thirty 40 twenty thirty 40 Water resistance of granules, points Dry caustic soda 5 - - - - 0 10 - 0 - 0 0 fifteen 2 2 0 one one twenty - 3 0 3 - Dry potassium hydroxide 5 - - - - - 10 - - - 0 0 fifteen 2 2 - one 2 twenty four - - four -

Table 3 shows:

that not one of the tested samples is fully softened;

that samples obtained from solid hydrosilicate gels, which were made at a specific consumption of any dry caustic alkali at a level of about 15 kg / 100 kg of siliceous raw materials of any origin, have a relative water resistance of at least two points and

that increasing the specific consumption of any dry caustic alkali to 20 kg / 100 kg of siliceous raw materials with an initial moisture content of about 30% reduces the water resistance of expanded granules.

Industrial applicability

The proposed method is easily feasible using publicly available, including environmentally harmful technogenic silica raw materials, dry caustic alkalis and standard mixers made of carbon steel.

Solid hydrosilicate gels can be used in the production of various (including composite) materials.

It should be especially noted that granular solid hydrosilicate gels, which are capable of swelling and surface melting when heated, serve as mineral analogues of polymer composite materials (in particular, based on polystyrene or polyvinyl chloride), which include foaming agents.

These properties of granular solid hydrosilicate gels make it possible to at least partially replace them with polymer binders such as phenolic, urea and melamine-formaldehyde resins in the manufacture of products such as plates based on basalt fibers, plywood, organic-mineral pipes, etc. pressing or extrusion methods. Moreover, it is advisable to use small fractions of granular solid hydrosilicate gels in combination with natural, styrene-butadiene or acrylic-styrene latex, polyvinyl acetate emulsion, animal and plant adhesives and other adhesive-active materials in the production of various non-woven materials.

Claims (7)

1. A method of manufacturing a solid hydrosilicate gel, including: grinding a porous silica raw material containing at least 70 wt.% Amorphous SiO ₂ to obtain silica sand, dosing this sand and air-dried granular caustic alkali, loading them into a reactor with an included stirrer and mixing, accompanied by self-heating, until a hot viscous semi-finished product is obtained, unloading the hot viscous semi-finished product in containers and holding this semi-finished product in containers with gradual natural cooling m to a temperature close to ambient temperature to give a solid mature hydrosilicate gel. 2. The method according to claim 1, in which the porous silica raw material is crushed in sand with a particle size of not more than 0.5 mm 3. The method according to claim 1, in which the moisture content of the silica raw material is normalized by drying excessively wet or by moisturizing dry silica sand. 4. The method according to claim 3, in which excessively wet siliceous sand is dried at a temperature not exceeding 100 ° C before loading into the reactor. 5. The method according to claim 3, in which dry silica sand is moistened by supplying water with a temperature of from 80 to 95 ° C to the reactor with the stirrer turned on. 6. The method according to claim 1, in which the solid hydrosilicate gel is crushed into granules from 20 to 5.00 mm in size and these granules are dried at a temperature below 150 ° C until they lose their ability to stick together. 7. The method according to claim 6, in which these granules are dried in a fluidized bed in a stream of air at a temperature of from 110 to 120 ° C.