RU2487102C1 - Method to manufacture light-weight heat insulation items for lining of thermal aggregates - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: method may be used to manufacture light-weight silica-alumina items of normal dimensions and simple cuts, designed for lining of thermal aggregates in zones with temperature of up to 1250°C, not exposed to action of melts, wear forces and mechanical shocks. The method includes preparation of a charge from chamotte, a binder and additives, shaping, drying and baking of items.

EFFECT: higher strength of light-weight heat insulation items for lining of thermal aggregates with preservation of low density and heat conductivity.

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Description

The invention relates to metallurgy and can be used in the manufacture of lightweight aluminosilicate products of normal sizes and simple shapes designed for lining of thermal units in areas with temperatures up to 1250 ° C, not exposed to melts, abrasive forces and mechanical shocks.

For these purposes, a known method of manufacturing lightweight products (Collection of technological instructions. Ministry of ferrous metallurgy of the USSR, SOYUZOGNEUPOR, Sukholozhsky refractory production of the Bogdanovo refractory plant, Sukhoi Log, 1985, pages 49-62) [1]. The known method involves mixing the components of the mixture, namely: clay - as a binder, fireclay - as an exhaustive additive, sawdust - as a burnable additive. At the same time, in the manufacture of products with an apparent density of 1.3 g / cm ³ , clay of the Troitsko-Bainovsky deposit in the amount of 37 wt.% Is used as a binder, imported chamotte scrap and fireclay battle from the marriage of products in the amount of 17 wt. %, sawdust is introduced into the mixture in the amount of 46 wt.% (p. 49-56 [1]).

In the manufacture of products with an apparent density of 1.0 g / cm ³ , a clay mixture is used as a binder: Troitsko-Bainovsky TB-4 and kaolin of the Nevyansk, Polozhy, Glukhovets and Kyshtym deposits in a ratio of 5: 1 or 4: 1, depending on plasticity clay TB-4. The components of the mixture are used in the amount of mass%: a mixture of clays - 36, chamotte - 3, sawdust - 61 (p.57-62 [1]). According to the known method, the prepared mixture is moistened with water during the entire mixing cycle, the products are molded by pressing a bar, which is cut into billets, pressed, products with an apparent density of 1.0 g / cm ³ and 1.3 g / cm ³ are dried at a temperature of from 170 ± 5 ° C and fired at a temperature of 1350 ° C. Receive products brands SHL-0.4, SHTL-0.6, SHL-0.9, SHL-1.0, SHL-1.3 SHLA-1,3, the compressive strength of which is in the range from 1 to 4 , 5 N / mm ² , thermal conductivity at an average temperature of 350 ± 25 is in the range of 0.2-0.6 W / (m * K), at an average temperature of 650 ± 50 - in the range of 0.25-0.7 W / (m * K).

The objective of the present invention is to obtain lightweight products for lining thermal units with high strength while maintaining low density and thermal conductivity, and is solved by the fact that the products are made from a mixture composition, wt.%:

Bauxite brand MiD D fractions 3-7 mm Chamotte of lump clay of the Arkalyk field fractions 1-3 mm Quartzite fraction 3-5 mm 4.9 Fiber brand Ruvol-M 4.9 Aluminosilicate Microspheres 20.0-59.0 Chamotte of lump clay of the Arkalyk field fractions 55 microns 11.8 White corundum fraction 0-0.063 mm 12.7 Ferrochrome slag 7.0 Additive Thermoplast T-3 3.0,

the amount of bauxite grade MiD D fractions of 3-7 mm and chamotte of lump clay of the Arkalyksky deposit of a fraction of 1-3 mm is 1.0-40 wt.% with a mass ratio of these components 1: 1, and the total amount of bauxite, chamotte of a fraction of 1-3 mm and aluminosilicate microspheres is 60 wt.%, when preparing the mixture, bauxite, chamotte fractions 1-3 mm, quartzite, fiber of the Ruvol-M brand are first mixed, mixed, moistened and Thermoplast T-3 additive is added, aluminosilicate microspheres, chamotte are loaded into the resulting mixture lump clay of the Arkalyk field fraction and 55 microns, white corundum, ferrochrome slag, mixed, the resulting mass is moistened with liquid glass with a density of 1.35 g / cm ³ , mixed and formed from it products that are fired after drying, raising the temperature to 500 ° C at 80-100 ° C / hour, from 500 to 1070 ° C at 150-200 ° C / hour, incubated at 1070 ° C for 6 hours, then cooled to 200 ° C without air supply when the oven is off.

The increase in strength with high heat resistance of products in the claimed method is achieved through the use of liquid glass as a binder, which forms fading during firing, as well as the use of Thermoplast T-3 additive, which has a highly developed specific surface, which contributes, firstly, to a better charge package, and secondly, increasing the plasticity of the mass and, consequently, reducing the water-cement ratio. In addition, it is known that in the region of high pore curvature high internal stresses arise, which negatively affects the strength of the product. Replacing a burnable additive with hollow aluminosilicate microspheres leads to a uniform distribution of pore curvature over the entire volume of the product, which prevents the appearance of areas of high internal stresses. Moreover, the use of aluminosilicate microspheres as a lightweight aggregate ensures the preservation of low density and thermal conductivity of products. Grains of large fractions of bauxite and chamotte of the indicated brands, as well as aluminosilicate fibers of the Ruvol-M brand, prevent the development of cracks, which leads to an increase in the heat resistance of products.

Fine-ground white corundum, consisting of more than 90% alumina, has a melting point significantly higher than the firing temperature and product life. Adding it to the mixture serves to increase the refractoriness of the products and reduces their linear shrinkage. During firing, quartzite undergoes polymorphic transformations, as a result of which it expands, which allows to compensate for the linear shrinkage of other components of the charge. The ratio of the components of the charge is selected based on a given final density of the obtained products, given that an increase in the mass fraction of aluminosilicate microspheres corresponds to a decrease in density. The order of preparation of the mixture due to the following factors. First, the components of the charge fraction of at least 1 mm are mixed with aluminosilicate fiber, which allows to achieve uniform distribution of fiber throughout the volume. The introduction of additives Thermoplast T-3, accompanied by wetting of the mixture, is produced after mixing the fibers and large grains, because moistened fiber practically does not lend itself to mixing, and before the introduction of fine-grained components of the charge. The latter is due to the need to achieve enveloping with the addition of large grains, which ensures their subsequent good interaction with the grains of fine fractions and the best packing of the charge. Aluminosilicate microspheres, chamotte fractions of 0.055 mm, white corundum, water glass and ferrochrome slag are introduced into the charge for the indicated reasons last. Obtained from the thus prepared mixture of the claimed composition of the product is subjected to firing. When the temperature rises to 500 ° C at 80-100 ° C / h, the Thermoplast T-3 additive burns out and the fusible compounds of the binder interact with the charge components. A further rise in temperature from 500 to 1070 ° C at 150-200 ° C / hour with holding at 1070 ° C for 6 hours provides sintering of the fine-grained charge components with coarse-grained components.

A new technical result achieved by the claimed invention is to increase the strength of lightweight thermal insulation products for lining thermal units while maintaining low density and thermal conductivity.

Example. To prepare the mixture used the following materials:

- Bauxite grade MID D fraction 3 ... 7 mm, the properties of which are given in table 1;

- Chamotte of lump clay of the Arkalyk field with a fraction of 0-70 mm of the ShKAR-45 grade according to STP 101-157-94. The properties are shown in table 2;

- Quartzite fraction 0-6 mm grade PPK-98, which meets the chemical composition requirements of TU 1511-027-59284560-2004;

- Chopped fiber of Cerafiber ™ (Bulk) brand, Ruvol-M grade mullite-siliceous heat treated according to the requirements of STO-05802307-1-001-2001, mass fraction of Al ₂ O ₃ ,%, not less than 50, change in mass fraction during calcination,%, not more than 0.6;

- Aluminosilicate microspheres of the MS-500 brand according to TU 5712-001-49558624-2003;

- Electrofused white corundum, crushed in accordance with TI 202-0-24-2008. It is possible to use corundum corresponding to the indicators of table 3;

- Self-scattering ferrochrome slag that meets the requirements of TU 14-5-295-99, TU 14-11-325-97.

The chemical composition of the slag:

CaO 48-52.3%

SiO ₂ 19.5-30.0%

Al ₂ O ₃ 4.0-6.7%

MgO 7.5-12.0%

Cr ₂ O ₃ 3.0-12.5%

FeO 0.1-3.3%

Phase composition: 65% γ - 2CaO · SiO ₂ ; 5% β - 2CaO · SiO ₂ ; 20-25% spinel MgO · Al ₂ O ₃ , FeO (Al, Cr) ₂ O ₃ ;

- Sodium liquid glass that meets the requirements of GOST 13078-81;

- Additive Thermoplast T-3 TU 5746-048-58042865-2010.

To prepare the mixture used water for concrete and mortar that meets the requirements of GOST 23732.

The components of the mixture fall asleep in the mixer of intensive mixing, for example, IP-0.2 / 125, characterized by the largest volume of the mixture to be filled in 200 dm ³ . The mass is prepared in a mixer in portions of 100 kg. To prepare 100 kg of ATB-1.3 concrete, at the beginning, bauxite is loaded into the mixer in an amount of 14.3 kg, chamotte fractions 1-3 in an amount of 14.3 kg, quartzite in an amount of 3.6 kg, fiber Ruvol-M in an amount of 3 , 6 kg and stirred for 1 minute, add 4 liters of water and T-3 additive in the amount of 2.75 kg, mix for 1 minute and, without turning off the mixer, load aluminosilicate microspheres in the amount of 14.3 kg through the loading hatch, chamotte fraction of 0.055 mm in the amount of 8.6 kg, white corundum in the amount of 9.3 kg, ferrochrome slag in the amount of 5 kg and stirred for 2 minutes after the latest components. Next, the mass is moistened with 15 liters of water glass, diluted to a density of 1.35 g / cm ³ and finally mixed for 1 minute. The preparation of the mixture for the manufacture of concrete grades ATB-0.7, ATB-0.9, ATB-1.1 is carried out in a similar way, choosing the ratio of the components of the mixture, based on a given final concrete density of the grades obtained.

The finished mass is loaded into metal or wooden molds. First, fill out half of the form and include a vibrating table, for example, electromagnetic with an elastic return element. The oscillation amplitude of the table is 2.5 mm. Molding is carried out at 45 cu within 1 minute, after which the vibrating table is turned off. The form is completely filled with mass and immediately include a vibrating table. Molding is carried out at 40 cu for 1 minute, after which molding is continued at 25 cu within 1 minute. The surface of the molded product is leveled with a spatula.

After molding, the mold with the product is left to stand for 24 hours at a temperature in the range from + 25 ° C to + 35 ° C under a plastic film. After 24 hours, the forms with the products are disassembled, the products are exposed to air drying for 48 hours under a plastic film on wooden pallets coated with corrugated cardboard, at a temperature in the range from + 25 ° C to + 35 ° C.

After air drying, the products are placed in a batch dryer and dried at a temperature of from 20 ° C to 120 ° C with a rise in temperature from 20 ° C to 50 ° C for 24 hours, from 50 ° C to 120 ° C for 24 hours. In this case, the temperature of the coolant at the outlet of the dried in the range of 50 ... 70 ° C, exposure at maximum temperature for 24 hours. The products can be dried in a special mode: raising the temperature from 20 ° C to 120 ° C for 24 hours and holding at the maximum temperature for 24 hours.

After drying, the product is subjected to heat treatment in periodic furnaces with a sliding hearth. Products are planted in a "muffle" of fireclay products, 1.2 m high around the perimeter of the hearth of the furnace. The distance from the edge of the hearth is 25 cm. Temperature rise during the heat treatment period: up to 500 ° C at 80-100 ° C / hour; from 500 to 1070 ° C at 150-200 ° C / hour; exposure at 1070 ° C - 6 hours; furnace shutdown; cooling to 200 ° C, without air supply; furnace opening. Physico-chemical characteristics of thermal insulation concrete products of the brand ATB-0.7, ATB-0.9, ATB-1.1, ATB-1.3, obtained by the claimed method, are shown in table 4, from which it can be seen that at the same density values and thermal conductivity, products of these brands have twice the strength than products of the brands ШЛ-0,4, ШТЛ-0,6, ШЛ-0,9, ШЛ-1,0, ШЛ-1,3, ШЛА-1,3 obtained in a known manner.

Table 1 A method of manufacturing a lightweight thermal insulation products for lining thermal units Indicators Norm Mass fraction,% Al ₂ O ₃ , not less 84 Fe ₂ O ₃ , no more 2.0 SiO ₂ , no more 7.0 TiO ₂ , no more 4.0 CaO + MgO, no more 0.5 R ₂ O, no more 0.30 Rev. mass during calcination%, not more than 0.35 Moisture content, % 1,0 The apparent density of bauxite, g / cm ³ , not less 3,1 Grain composition: Fraction 3 ... 7 mm The remainder on the grid number 8 Not allowed Residue on net No. 6.3, passage through net No. 8.0%, within - 0 ... 15 Residue on net No. 5.0, passage through net No. 6.3,%, within - 25 ... 40 The remainder on the grid number 4.0, the passage through the grid number 5.0,%, within - 20 ... 30 The remainder on the grid number 3.2, the passage through the grid number 4.0,%, within - 15 ... 25 Pass through the grid No. 3.2,%, within 0 ... 15

table 2 The name of indicators Indicators Chemical composition, mass fraction,%: Al ₂ O ₃ , not less 45.0 Fe ₂ O ₃ , no more 2,5 Mass fraction of moisture,%, no more 5,0 Water absorption,%, no more 6.0 Refractoriness, ° С, not less 1750 Limit size of a piece, mm, no more
Grain content less than 0.5 mm,%, no more 70
25

Table 3 A method of manufacturing a lightweight thermal insulation products for lining thermal units Indicators Norm for corundum White Mass fraction,% Al ₂ O ₃ , not less 96.0 SiO ₂ , no more 0.5 Fe ₂ O ₃ , no more 0.2 MgO, no more 1,0 TiO ₂ , no more - Grain composition,% Fraction 0 ... 1.0 mm, incl. The remainder on the grid number 1.0, within 0 ... 10 Net balance No. 05, within 35 ... 45 The remainder on the grid No. 02, within 30 ... 40 Balance on grid No. 01, within 10 ... 20 Passage through mesh No. 01, within 5 ... 15 Mass fraction of moisture,%, no more 0.4

Table 4 A method of manufacturing a lightweight thermal insulation products for lining thermal units Name of indicator Norm for brand products ATB - 0.7 ATB - 0.9 ATB - 1.1 ATB - 1.3 HL - 0.4 SHTL - 0.6 HL - 0.9 HL - 1.0 HL - 1.3 SLA - 1.3 Mass fraction of Al ₂ O ₃ ,%, not less 35 35 35 35 36 Apparent density, g / cm ³ , no more 0.7 0.9 1,1 1.3 0.4 0.6 0.9 one 1.3 1.3 The compressive strength, N / mm ² , not less: after drying at 125 ° C 2,5 3,5 5 5.5 after heat treatment four 6 8 10 one 2,5 2,5 3 3,5 4,5 at temperature, ° С 1100 1250 1250 1300 Additional shrinkage at a temperature in ° C 1100 1200 1250 1300 1150 1150 1270 1300 1300 1400 in%, no more one one one one one 0.7 one one one one Thermal conductivity, W / (m * K), no more, at average temperature, ° С 350 + -25 0.25 0.4 0.5 0.6 0.2 0.25 0.4 0.5 0.6 0.6 650 + -50 0.3 0.5 0.6 0.7 0.25 0.3 0.5 0.6 0.7 0.7

Claims (1)

A method of manufacturing a lightweight thermal insulation products for lining thermal units, including the preparation of a mixture of chamotte, a binder and additives, molding, drying and firing of products, characterized in that the products are made from a mixture composition, wt.%:
Bauxite brand MiD D fractions 3-7 mm Chamotte of lump clay of the Arkalyk field fractions 1-3 mm Quartzite fraction 3-5 mm 4.9 Fiber brand Ruvol-M, 4.9 Aluminosilicate Microspheres 20.0-59.0 Chamotte of lump clay of the Arkalyk field fractions 55 microns 11.8 White corundum fraction 0-0.063 mm 12.7 Ferrochrome slag 7.0 Additive Thermoplast T-3 3.0,
the amount of bauxite grade MiD D fractions of 3-7 mm and chamotte of lump clay of the Arkalyksky deposit of a fraction of 1-3 mm is 1.0-40 wt.% with a mass ratio of these components 1: 1, and the total amount of bauxite, chamotte of a fraction of 1-3 mm and aluminosilicate microspheres is 60 wt.%, when preparing the mixture, bauxite, chamotte fractions 1-3 mm, quartzite, fiber of the Ruvol-M brand are first mixed, mixed, moistened with water and Thermoplast T-3 additive is added, aluminosilicate microspheres are loaded into the resulting mixture, chamotte of lump clay of Arkalykskoye field fr ktsii 55 microns, white corundum, ferrochromium slag, stirred, the resulting mass is moistened with liquid glass density of 1.35 g / cm ^3, stirred and formed into a product which, after drying, is calcined by raising the temperature to 500 ° C at 80-100 ° C. / h, from 500 to 1070 ° C at 150-200 ° C / h, incubated at 1070 ° C for 6 hours, then cooled to 200 ° C without air supply when the oven is off.