RU2721561C1 - Method of producing heat-insulating material - Google Patents

Abstract

FIELD: chemistry; construction.

SUBSTANCE: invention relates to production of construction materials, particularly those relating to production of porous heat-insulating articles, and can be used in production of heat-insulating material, especially light concrete, as well as heat-insulating fillings and heat-resistant insulation of heat apparatus. In the method of producing a heat-insulating material based on liquid glass, involving thorough mixing, milling and heat treatment of the components of the composition, additionally used as a fly ash component, lime-dust of lime produced during calcining of limestone, and waste solution of iron etching with sulphuric acid at the following ratio of components, wt. %: liquid sodium glass 25–30, flue ash 42–44, lime-dust lime 9–12, waste solution of iron etching with sulphuric acid 18–20, wherein milling, mixing and heat treatment of components is carried out in three stages: at the first stage in the bead mill, mixing liquid sodium glass and fly ash to particle size of 1–3 mm, heating to temperature of 150–160 °C for 6 hours, obtained suspension of sodium aluminosilicate is transferred to two-roller high-speed mixer; at the second stage in a reactor with a high-speed stirrer, neutralization of the spent solution of iron etching with sulphuric acid by lime-dust dust is performed to pH = 8.5–9.0 at temperature of 80–90 °C and a suspension of calcium sulphate and iron hydroxide is obtained, then flue ash is added and neutralization of said suspension is performed to pH = 6.5–7.0 and a suspension containing a mixture of gypsum and calcium aluminate is obtained, which is fed into a high-speed two-roller mixer, in which it is mixed with a suspension of sodium aluminosilicate, in a third stage the resulting slurry from the high-speed two-roll mixer spray fed to the fluidized bed furnace, in which it is heat treated flue products with an excess of oxygen at temperature of 140–350 °C and obtaining heat-insulating material with particle size of 0.6–1.0 mm, including expanded sodium aluminosilicate, expanding cement - product of interaction of calcium aluminosilicate with gypsum and iron oxide pigments of yellow colour at temperature of 140 °C and red colour at temperature of 350 °C.

EFFECT: technical result is high strength, possibility of producing heat-insulating materials of yellow or red colours, recycling wastes from production.

1 cl, 1 dwg, 1 tbl, 2 ex

Description

The invention relates to the production of building materials, in particular, related to the production of porous heat-insulating products, and can be used in the manufacture of heat-insulating material, especially lightweight concrete, as well as heat-insulating backfill and heat-resistant insulation of heat devices.

A known method of obtaining a heat-insulating material, including the preparation of a raw mixture containing, wt:% liquid glass - 82-89.3, filler - silica fume - waste production of crystalline silicon - 8.93-16.4 and the sodium salt of an inorganic acid - sodium bicarbonate - 1.6-1.77, granulation of the mixture and its subsequent heat treatment at 100 ° C for 1 hour and then at 250 ° C for an hour [RU 2128633, 1999]. This method has the following disadvantages:

1. The complexity of the process.

2. Low quality of the obtained insulating material.

A known method of obtaining structural and heat-insulating building material based on aluminosilicate microspheres, including mixing aluminosilicate microspheres and a binder - water glass, molding, heat treatment, aging, cooling, use liquid glass sodium and / or potassium with a module 1-4 and density 1 , 1-1.47 g / cm ³ , carry out molding with a specific load of 1.5-5 MPa, heat treatment, including: stage I thermal shock - by raising the temperature to 100-130 ° C in 7-15 minutes, exposure - at 100 -130 ° C for 7-15 minutes, stage II of thermal shock - by raising the temperature to 300-550 ° C for 10-30 minutes, holding for 40-80 minutes and cooling in the oven for 5-8 hours, with the following ratio of components % vol .: aluminosilicate microspheres 65-97, the specified liquid glass 3-35 [US Pat. RF number, 2455253, 1999].

This method has the following disadvantages:

1. A very sophisticated technology for producing heat engineering material.

2. The duration of the process and high energy consumption.

A known method of producing a heat-insulating material containing liquid glass, finely ground fireclay, ferrochrome slag and chamotte scrap as a filler, characterized in that it additionally contains neutralized galvanic sludge, and as chamotte scrap - unfractionated slagged chamotte scrap with a grain size of 0.01 ... 20 mm in the following ratio of components, mass. %: liquid glass - 17 ... 22; finely ground fireclay - 8 ... 11; ferrochrome slag - 3 ... 6; unfractionated slagged fireclay scrap with a size of 0.01-20 mm - 60 ... 67; neutralized galvanic sludge - 1 ... 5 (US Pat. RF No. 2187482, С04В 28/08, 2005).

This method has the following disadvantages:

1. High energy consumption for grinding the raw materials used.

2. Low strength of the products.

The closest in technical essence is a method for producing a heat-insulating porous material based on liquid glass, including thoroughly mixing the components of the composition containing liquid glass, sodium chloride, preparing the products and heat treating them at 350 ° C, part of the liquid glass is thoroughly pre-treated before thoroughly mixing the components in the temperature range of 250 ... 300 ° C, then the resulting porous mass, crushed to a size of 2 ... 5 mm with a bulk density of 50 ... 80 kg / m ³ , is thoroughly mixed with liquid glass and sodium chloride, in the following ratio of components, mass. %: water glass with a density of 1.45 g / cm ³ - 70 ... 80, sodium chloride - 10, the specified ground mass - 10 ... 20 [US Pat. RF №2504525, С04В 28/08, 2014].

This method also has the following disadvantages:

1. High energy consumption with two times the heat treatment of raw material components.

2. Low strength of the insulating material (depending on the composition varies from 0.075 to 1.3 MPa).

The technical objective of the proposed method is to reduce the cost of obtaining insulation material due to the disposal of industrial waste, increasing strength and the possibility of obtaining materials of yellow or red colors.

The stated technical problem is solved due to the fact that in the method for producing a heat-insulating material based on liquid glass, including thoroughly mixing, grinding and heat treating the components of the composition according to the invention, they are additionally used as components of fly ash, dust dust from lime calcined by calcining limestone , and the spent solution of iron etching with sulfuric acid, in the following ratio of components, mass. %: liquid sodium glass - 25 ... 30, fly ash - 42 ... 44, dust fly ash - 9 ... 12, the spent solution of iron etching with sulfuric acid -18 ... 20, and grinding, mixing and heat treatment of the components is carried out in three stages: at the first stage, liquid sodium glass and fly ash are mixed and crushed in a bead mill to a particle size of 1 ... 3 mm, heated to a temperature of 150 ... 160 ° C for 6 hours, the resulting suspension of sodium aluminosilicate is transferred to a twin-roll high-speed mixer; at the second stage, in a reactor with a high-speed stirrer, neutralize the spent solution of iron etching with sulfuric acid dust-fly-off lime first to pH = 8.5 ... 9.0 at a temperature of 80 ... 90 ° C and a suspension of calcium sulfate and iron hydroxide is obtained, then ash is added -unos and neutralize the specified suspension to pH = 6.5 ... 7.0 and get a suspension containing a mixture of gypsum and calcium aluminate, which is fed to a high-speed twin roll mixer, which is mixed with a suspension of sodium aluminosilicate, in the third stage, the suspension obtained from high-speed a twin-roll mixer is sprayed into a fluidized bed furnace, in which it is subjected to heat treatment with smoke products with an excess of oxygen at a temperature of 140 ... 350 ° C and a heat-insulating material with a particle size of 0.6 ... 1.0 mm, including expanded sodium aluminosilicate, expanding cement - a product of the interaction of calcium aluminosilicate with gypsum and yellow iron oxide pigments at a heat treatment temperature fabrics 140 ° C and red - at a heat treatment temperature of 350 ° C.

The waste used is characterized by the following chemical composition:

Liquid glass corresponding to GOST 130078-81, density = 1.45 g / cm ³ , pH> 8, containing, wt%: SiO ₂ - 28.9; Na ₂ O - 10.2, water - the rest.

Fly ash obtained at the Troitsk state district power station when burning Ekibastuz coal contains, wt.%: SiO ₂ - 54.8; Al ₂ O ₃ - 25.5; Fe ₃ O ₃ - 5.9; CaO - 0.8; R ₂ O - 0.9; SO ₂ 0.6.

Lime fly ash obtained by Mechel OAO (Ch. Yelyabinsk) in large volumes upon calcination of limestone contains, wt.%: CaO-74.7; SiO ₂ - 1.8; MgO - 2.8 and CaCO ₃ - 21.2. The waste is partially used to neutralize acidic wastewater.

The spent solution of iron etching with sulfuric acid, obtained by etching pipes with sulfuric acid at the Chelyabinsk Pipe Plant, containing, wt.%: H ₂ SO ₄ - 4 ... 5; FeSO ₄ - 18 ... 20; H ₂ O - the rest is neutralized by lime and the resulting gypsum with a high content of iron oxide does not find industrial application.

It is known that when the waste used in the production of heat-insulating materials contains calcium, aluminum and silicon oxides, as well as sulfates and water glass, during their processing under certain conditions, binders of high activity can be obtained from such waste: aluminosilicate binder (sodium aluminosilicate), building gypsum and calcium aluminate, the presence of which in heat-insulating materials increases their strength, which allows them to be used for the manufacture of products for various applications (for the manufacture of facing plates not only for their internal but also for external use [Refractory cements / Melnik MT, Ilyukha N.G., Shapovalova N.N., - Kiev: Vishcha school, 1984. - 123 s].

Considering the above, it is proposed to process these wastes in the following sequence: at the first stage, the calculated amounts of liquid sodium glass and fly ash are loaded into a bead mill and mixing and grinding are carried out simultaneously to a particle size of 1 ... 3 mm. Grinding less than 1 mm requires a large expenditure of energy and time, and grinding particles larger than 3 mm dramatically reduces the further expansion of liquid glass. Together with grinding, liquid glass interacts with aluminum oxide of fly ash, while the temperature in the bead mill is raised to 150 ... 160 ° C by supplying steam to the steam jacket for 6 hours, and reaction (1) proceeds in this suspension and the suspension forms sodium aluminosilicate (aluminosilicate adhesive bond):

It is known that in aluminosilicate solutions-systems in which equilibria between monomer and polymer compounds are carried out, the content of polymer ions increases with increasing alkalinity of the medium due to the fact that aluminate ions shift the equilibrium towards an increase in the concentration of polymer silicate ions, which makes such systems are more stable than individual silicate solutions [Sychev MM]. Inorganic adhesives, L., Chemistry, 1986, 93 s].

The maximum content of Al ₂ O ₃ , which may be contained in the aluminosilicate adhesive bonding while maintaining its stability, is 10% (in terms of dry oxides). With an increase in the content of alumina, the adhesive bonding thickens and it turns into a gelatinous mass. When these solutions are mixed, gels of sodium aluminosilicate of normal hardening and high compressive strength up to 600-900 MPa are formed, depending on the ratio of these components.

After the end of the reaction (the cessation of steam evolution) from the bead mill, the formed suspension of sodium aluminosilicate is transferred to an intermediate tank and then from it to a twin-roll high-speed mixer.

At the second stage, in a reactor equipped with a high-speed mixer during its operation, neutralize the spent etching solution of metal dust-fly-lime to pH 8.5 ... 9.0. As a result of neutralization, the temperature rises in the reactor to 80 ... 90 ° C and the reactions (2) and (3) below proceed with the formation of a suspension of calcium sulfate and iron hydroxide:

After completion of the reactions (termination of steam evolution), fly ash is added to the same reactor with the stirrer operating until a pH of 6.5 ... 7.0 is reached, while reactions (4) and (5) proceed in the reactor with the formation of gypsum suspensions and calcium aluminate:

After the reactions are completed, a mixture of suspensions of gypsum, calcium aluminate and iron hydroxide is fed to a two-roll high-speed mixer, in which it is thoroughly mixed with a suspension of sodium aluminosilicate, which is available there, after being transferred from a bead mill and an intermediate tank. Next, the mixture is pumped to the third stage.

At the third stage, the mixture of suspensions is pumped by spraying into the upper part of the fluidized bed furnace, excess oxygen and a temperature of 140 ... 350 ° C are maintained in the heated flue products and three processes occur simultaneously in the furnace: sodium aluminosilicate swelling with the formation of particles with a size of 0.6 ... 1.0 mm, the interaction of calcium aluminate with gypsum with the formation of expanding cement and the oxidation of iron hydroxide to oxides to produce iron oxide pigments - yellow - at a temperature of 140 ° C and red - at a temperature of 350 ° C according to the following reactions (6 -8):

The study found that when the silicate mixture is melted, its expansion begins at a temperature above 48 ° C, and the most complete at 350 ° C [Konev V.I., Danilov V.V. Production and use of soluble glass. L .: Stroyizdat, 1991, p. 177].

Under such conditions, the formation of high strength gypsum by reaction 4 also occurs, which is explained as follows. It is known that natural gypsum in the hardened state does not have high compressive strength (2 ... 16 MPa) and its strength decreases with moisture. It is possible to increase the strength of gypsum products by finely grinding a-hemihydrate, obtained by heat treatment in an autoclave in saturated steam at a pressure of 0.15 ... 0.3 MPa. In this regard, in an industrial environment, to obtain high-quality gypsum, natural gypsum is subjected to heat treatment in steamers (steam boilers) at a temperature of 140 ... 190 ° C and a pressure of 1.3 atm. within 1.0 ... 1.5 hours. Products obtained using such gypsum have a compressive strength of 40 ... 55 MPa after 1.5 hours. [Brief chemical encyclopedia. - M .: Soviet Encyclopedia, 1964, T1, S. 715].

Due to the fact that the conditions of the steam boiler are created under the indicated conditions in the fluidized bed furnace, the gypsum obtained is of high quality, and the heat-insulating materials made on its basis are suitable not only for insulation of industrial heating networks, but also for thermal protection some industrial facilities and thermal units. The advantages of the proposed method is also confirmed by the data given in the following examples.

Example 1. 250 g of the indicated chemical composition of liquid glass is poured into a bead mill and 200 g of the given composition of fly ash are added to it, the mixture is heated to a temperature of 150 ° C and held for 6 hours, while reaction (1) proceeds in it and 450 g of suspension are formed with an admixture of 330 g of sodium aluminosilicate. At the same time, 200 g of the above composition of the spent metal-iron etching solution with sulfuric acid is poured into the reactor and 120 g of the specified lime dust-entrainment composition is added to the reactor with the stirrer turned on until the pH of the suspension is 8.5, while the temperature in the reactor rises to 80 ° C and forms 320 g of a mixture containing calcium sulfate and iron hydroxide according to reactions (2) and (3). After the completion of the reactions (termination of vapor evolution), 230 g of fly ash were added to the reactor with a working stirrer to a pH of 6.5, while reactions (4) and (5) proceeded in the reactor with the formation of gypsum and iron hydroxide in the suspension. After completion of the reactions, the mixture of suspensions from the reactor and the suspension from the bead mill were placed in the mixer and thoroughly mixed, then the mixture was placed in a platinum glass, which was heat treated in a muffle furnace at a temperature of 140 ° C until the color of the mass changed from gray to yellow. During heat treatment, the mixture was purged with hot smoke products with an excess of oxygen, and reactions (6) and (7) proceeded in it with the formation of expanding cement and yellow iron oxide pigment. After cooling the mixture to 40 ° C, 1000 g of thermal insulation material was obtained containing 330 g of foamed particles of sodium aluminosilicate, 218.8 g of expanding cement and 101.2 g of yellow iron oxide pigment. The strength of the obtained insulating material 154 MPa.

The quality of the obtained heat-insulating material (dispersion and strength) was determined according to GOST 310.3-76 (2003), with production of samples 40 × 40 × 40 mm in size on a vibrating table and pressing them and testing them in a day.

Example 2. 300 g of the indicated chemical composition of liquid glass are poured into a bead mill and 320 g of the given composition of fly ash are added to it, the mixture is heated to a temperature of 160 ° C and held for 6 hours, while reaction (1) proceeds in it and 640 g of suspension are formed with an admixture of 540 g of sodium aluminosilicate. At the same time, 180 g of the above composition of the spent solution of iron etching with sulfuric acid is poured into the reactor and 90 g of the specified composition of lime dust-entrainment is added to it with the stirrer turned on until the suspension reaches pH = 9.0, while the temperature in the reactor rises to 90 ° C and 270 g of a mixture containing calcium sulfate and iron hydroxide are formed according to reactions (2) and (3). After the completion of the reactions (termination of vapor evolution), 100 g of fly ash was added to the reactor with a working stirrer to a pH of 7.0, while reactions (4) and (5) proceeded in the reactor with the formation of gypsum and iron hydroxide in an amount of 188, respectively , 6 g and 81.4 g. After completion of the reactions, the mixture of suspensions from the reactor and the suspension from the bead mill were placed in the mixer and mixed thoroughly, then the mixture was placed in a platinum glass, which was heat treated in a muffle furnace at a temperature of 350 ° С until the color of the mass changed from gray to red. During heat treatment, the mixture was purged with hot smoke products with an excess of oxygen and reactions (6) and (7) proceeded in it with the formation of expanding cement and red iron oxide pigment. After the mixture was cooled to 40 ° C, 1000 g of heat-insulating material was obtained containing 540 g of foamed particles of sodium aluminosilicate, 188.6 g of expanding cement and 84.4 g of red iron oxide pigment. The strength of the obtained insulating material is 174.8 MPa. Tests of the samples were carried out as in example 1.

The technological equipment (Fig.) Includes the following equipment: 1 - the capacity of liquid glass; 2 - fly ash bin; 3 - silo dust-entrainment of lime; 4 - the capacity of the spent solution of iron etching; 5 - bead mill; 6 - interstitial capacity; 7 - reactor; 8 - twin roll mixer; 9 - pump for pumping slurry; 10 - fluidized bed furnace; 11 - capacitor; 12 condensate capacity; 13 - cooling drum; 14 - bunker of finished products.

The process of formation of heat-insulating materials proceeds in the following sequence. At the first stage, the interaction of liquid glass with aluminum oxide of fly ash is carried out in a bead mill 5, to which predetermined amounts of the indicated reagents are supplied from tank 1 and hopper 2, respectively, while the temperature in the bead mill is raised to 150 ... 160 ° C by steam supply in the steam jacket of the mill, while reaction (1) proceeds in suspension. After the reaction (termination of steam evolution), the suspension through the intermediate tank 6 is fed into a twin-roll mixer 8.

At the second stage, the reactor 7 neutralizes the spent solution of iron pickling with dust-entrainment of lime, supplied respectively from tank 3 and hopper 4, to a pH of 8.5 ... 9.0, while the temperature in the suspension rises to 80 ... 90 ° C and flows reactions (2 and 3), after completion of the reactions, fly ash is added to the reactor with a working stirrer to a pH of 6.5 ... 7.0 and reactions (4 and 5) proceed. After completion of the reactions, the suspension is transferred to a twin roll mixer 8, where it is thoroughly mixed with the suspension previously supplied from a bead mill.

In the third stage, the mixed suspensions by pump 9 are sprayed into the upper part of the fluidized bed furnace 10, in which three processes simultaneously occur at a temperature of 140 ... 350 ° C: drying the suspension, foaming sodium aluminosilicate and grinding it to a particle size of 0.6 ... 1 , 0 μm. During the heat treatment of the suspension in the furnace, the resulting vapors are condensed in the condenser 11 and the condensate formed is collected in the tank 12 and is used in the process as it accumulates. After the end of the processes, the hot foamed mass from the furnace is transferred by a screw to the cooling drum 13, in which it is cooled to 40 ... 50 ° C, after which it is transferred to the finished product bin 14.

In the table. 1 shows the characteristic of the technological equipment necessary for the implementation of this method.

The obtained insulating material meets the requirements of the current technical documentation, surpassing the prototype in mechanical strength. The proposed method allows to reduce the cost of obtaining heat-insulating material through the use of specialized equipment, disposal of industrial waste, as well as to increase its strength through the use of industrial waste and processing technology.

Claims (1)

A method of obtaining a heat-insulating material based on liquid glass, including thoroughly mixing, grinding and heat treating the components of the composition, characterized in that it is additionally used as components of fly ash, dust dust of lime obtained by calcining limestone, and an spent solution of iron etching with sulfuric acid, in the following ratio of components, wt.%: liquid sodium glass 25-30, fly ash 42-44, dust fly ash 9-12, the spent solution of iron etching with sulfuric acid 18-20, and grinding, mixing and heat treatment of the components is carried out in three stages: in the first stage, liquid sodium glass and fly ash are mixed and crushed in a bead mill to a particle size of 1-3 mm, heated to a temperature of 150-160 ° C for 6 hours, the resulting suspension of sodium aluminosilicate is transferred to a twin-roll high-speed mixer ; at the second stage, in a reactor with a high-speed stirrer, neutralization of the spent solution of iron etching with sulfuric dust dust-lime is carried out first to pH = 8.5-9.0 at a temperature of 80-90 ° C and a suspension of calcium sulfate and iron hydroxide is obtained, then ash is added -unos and carry out the neutralization of the specified suspension to pH = 6.5-7.0 and get a suspension containing a mixture of gypsum and calcium aluminate, which is fed to a high-speed twin roll mixer, which is mixed with a suspension of sodium aluminosilicate, in the third stage, the suspension obtained from high-speed a twin-roll mixer is sprayed into a fluidized bed furnace, in which it is subjected to heat treatment with smoke products with an excess of oxygen at a temperature of 140-350 ° C and a heat-insulating material with a particle size of 0.6-1.0 mm, including expanded sodium aluminosilicate, expanding cement - a product of the interaction of calcium aluminosilicate with gypsum and yellow iron oxide pigments at a heat treatment temperature fabric 140 ° C and red at a heat treatment temperature of 350 ° C.

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