RU2379264C1 - Raw mix for manufacturing of ceramic vermiculite products - Google Patents

Abstract

FIELD: construction engineering.

SUBSTANCE: raw mix for manufacturing of ceramic vermiculite products concerns high-temperature heat insulation presented with bricks and boards, industrial machinery, particularly for fettling of cathodes in electrolytic cells in aluminium industry and building materials industry. The raw mix for manufacturing of ceramic vermiculite products contains expanded vermiculite, firestone and clay-phosphate binder in the following ratio, wt %: expanded vermiculite - 65-25; firestone - 25-65; clay-phosphate binder - 7-15.

EFFECT: higher durability, thermal stability, fire resistance and lower decrease shrinkage of products.

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Description

The invention relates to high-temperature (up to 1100 ° C) thermal insulation in the form of bricks and plates, industrial equipment, in particular for lining the cathode part of electrolytic cells in the aluminum industry, as well as the building materials industry.

Known thermal insulation and structural material and the method of its production on the basis of expanded vermiculite refractories (Russian Federation, item No. 2161142 C1, class C04B 28/24, 06/06/2000), which consists in mixing the expanded vermiculite with a binder - liquid glass and a technological additive , form the formation and carry out hot pressing with a hot gaseous agent blowing with isothermal exposure; a material selected from the group is used as a technological additive: vermiculite dust captured during vermiculite roasting, amorphous to organic matter is of rhizomene, and flue gases of vermiculite kilns or carbon dioxide with a temperature of 100-350 ° C are used as a hot gaseous agent.

The disadvantages of the method and material are that it is less productive due to the high technological and time costs, and liquid glass is used as a binder, which reduces the fire resistance of the product and, as a consequence, the scope.

Known high-temperature heat-insulating material (SU 1648938 A1, class C04B 38/08, 28/34), consisting of expanded vermiculite grade 150, which is closed with aqueous solutions of acids of 10% concentration. The mixture is placed in a reactor, where it is kept at normal atmospheric pressure and normal temperature at rest until the liquid phase of the mixture reaches pH 7, then the acid-treated expanded vermiculite is pressed under pressure of 15 and 30 kg / cm ^2, respectively, for heat-insulating and heat-insulating structural products and served for drying at 100-120 ° C.

The disadvantages are that with a high consumption of acid phosphate binder (up to 26 wt.%), The strength of the products does not exceed 2 MPa.

The closest technical solution to the claimed method is a method for the production of heat-insulating ceramo-vermiculite products (SU 1583395 A1, class С04В 35/56, publ. 07.08.1990, (prototype)), including the preparation of clay slip, the introduction of a refractory filler in the amount of 25- 45 parts by weight from its entire content, mixing the mixture with expanded vermiculite and the remaining part of the refractory aggregate, heated to 80-95 ° C, keeping the mass for 1.5-2.0 hours, molding, drying and firing, which is carried out by placing in a furnace with a temperature of 1000-1050 ° C, withstand them for 35-45 minutes, increase the temperature to 1150 ° C and withstand 75-105 minutes

The disadvantages of this method and material are its low manufacturability, in particular, too hard heating mode, as a result of this, the resulting products have low mechanical strength due to burnout of vermiculite and due to volumetric and linear shrinkage - increased density and deformability.

The technical result of the invention is to increase the strength of the product, through the use of phosphate binders, lower linear and volumetric shrinkage and deformability, due to the linear heating mode, and, as a result, increase operational and resource characteristics.

The technical result is achieved in that in the raw material mixture for the production of ceramic-vermiculite products, including expanded vermiculite, refractory clay and a binder, it is new that it contains an aluminophosphate binder, in the following ratio of components, wt.%:

expanded vermiculite - 65-25

refractory clay - 25-65

aluminophosphate binder - 7-15

Phosphate ligaments are solutions of phosphates (usually acidic) obtained either by the neutralization of an acid (oxides or hydroxides) or the dissolution of phosphates in water. Solutions of acid phosphates have astringent properties.

The use of aluminophosphate binder allows to obtain materials with a number of valuable properties: with high compressive strength, heat resistance and fire resistance, at low sintering temperatures.

Refractory clay and phosphoric acid were used to prepare the binder. The clay phosphate binder was obtained by boiling clay with phosphoric acid for 5-7 minutes. Moreover, the ratio in the binder

P ₂ O ₅ / Al ₂ O ₃ = 0.56.

The use of refractory clay allows, due to its high ductility and sinterability, to form products of various shapes, excluding recoil due to the elasticity of the product; to increase refractoriness, the linear rate of heating of the product allows to minimize linear and volumetric shrinkage, not bringing the temperature to the maximum at which the clay is sintering strongly, thus it is possible to obtain products of low density and eliminate defects inside the crystal lattice of the fired sample.

The above distinguishing features from the prototype signs allow us to conclude that the claimed technical solutions meet the criterion of "novelty."

The features distinguishing the claimed technical solutions from the prototype are not identified in other technical solutions and, therefore, provide the claimed solution with the criterion of "inventive step".

In the Krasnoyarsk Territory, the group of Uyar deposits is one of the largest reserves of refractory clays in terms of quantity. Extraction of clay refractory raw materials is carried out at the Kampanovskoye field, which is part of the Uyarskoye field group.

The characteristics of the refractory clay of the Kampanovskoye field are given below:

The microscopic characteristic is white with a yellow tint, contains a large number of granular inclusions (11-34%), a significant part of which is 0.5-50 mm in size. Granular impurities of kaolins are represented by quartz, feldspar, and iron hydroxides.

Humidity - 15.5%.

The reaction with 10% Hcl - does not boil.

Granulometric composition according to GOST 21216-81 (pipette method). Fraction size in mm: more than 0.05 - 16.1%, 0.05 ÷ 0.01 - 38.3%, 0.005 ÷ 0.001 - 14.7%, less than 0.001 - 9.7%.

Density - 1.96 t / m ³ .

The compressive strength of calcined samples at 1200 ° C is 29.4 MPa.

Refractoriness -1690 ° С.

Sintering - high temperature sintering.

Sensitivity to drying - 0.91 (insensitive).

Normal molding humidity is 18.6%.

Plasticity - 9.4 (moderately plastic).

The binding capacity of the dried samples is 2.1 MPa.

The compressive strength of calcined samples at 1000 ° C is 8.9 MPa.

X-ray phase analysis - kaolinite - 73%, α-SiO ₂ - a small amount, microcline - a little, muscovite - traces.

The chemical composition of refractory clay is shown in table 1:

No.
p / p Name
raw materials The content of oxides,% SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ TiO ₂ Cao MgO K ₂ O Na ₂ O p.p.p. one Kaolin of the Kampanovsky field 54.78 29.99 1.29 0.88 0.70 0.40 1.43 0.11 10.42

A method of producing ceramo-vermiculite products is as follows: in a predetermined ratio, the charge components are dosed in a predetermined ratio (expanded vermiculite, refractory clay), loaded sequentially into a mixing device (twin-shaft mixer, Z-shaped mixer) and thoroughly mixed (10-15 min), after which moisturize with a clay phosphate binder to a dry mass and mix for another 10-15 minutes, the prepared mixture is unloaded, dosed, compacted and pressed in a rotary press. Then it is dried in ovens to a residual moisture content of 3% at a temperature (150 ± 10 ° C), after which the dried products are fired at a temperature of 950-1050 ° C.

For the production of high-temperature heat-insulating products, for example, a mixture of the following composition is used, wt.%: Expanded vermiculite - 65, refractory clay - 25, clay phosphate binder - 10.

Examples of the composition of the charges are given in table 2.

table 2 Components Composition, wt.%: Expanded Vermiculite 65 55 25 Fire-clay 28 35 60 Clinophosphate binder 7 10 fifteen

Varying the content of expanded vermiculite and refractory clay in the mixture allows to reduce or increase the density and strength; changing the ratio of phosphoric acid in the phosphate binder allows you to increase or decrease the sintering ability, porosity and refractoriness.

The test results of the products are presented in table 3.

Table 3 Product Properties Indicators for example famous proposed one 2 3 The density of products, kg / m ³ 585 590 598 605 Compressive strength, MPa 1.39 2,53 2.67 2.86 Additional shrinkage,% 0.39 0.23 0.26 0.32 Heat resistance, the number of cycles of air heat exchange 134 139 140 137 Refractoriness, ° С - 1415 1455 1520

The advantages of the obtained ceramic-vermiculite products are in the increase of their refractoriness due to the introduction of refractory clay and a phosphate binder into the structure. Reduced linear and volumetric shrinkage and the exclusion of deformation of the product occurs due to preliminary drying and firing of the product. By reducing technological and time costs, there is an increase in production efficiency.

Claims (1)

A raw material mixture for the production of ceramic-vermiculite products, including expanded vermiculite, refractory clay and a binder, characterized in that it contains a phosphate binder as a binder in the following ratio of components, wt.%:
expanded vermiculite 65-25 fire-clay 25-65 aluminophosphate binder 7-15