RU2478586C2 - Method of producing heat-insulating material and mixture for production thereof - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of heat-insulating building materials. Amorphous silicic rock, sodium hydroxide and hot water at 80-90°C are mixed in a reactor for 10-15 minutes until formation of sodium hydrosilicate. The obtained liquid is then mixed with expanded pearlite for 10 minutes. The mixture is foamed in the closed volume of a metal mould at temperature of up to 700°C for 0.5-1 hours. The finished articles are annealed at temperature ranging from 700°C to 360°C for 1 hour, followed by cooling on air. The mixture for producing heat-insulating material contains the following components, wt %: expanded pearlite with density of 75-100 kg/m³ - 20; amorphous silicic rock - 28; sodium hydroxide - 12; water - 40.

EFFECT: low temperature and shorter time for foaming the mixture and annealing the articles.

2 cl, 1 tbl

Description

The invention relates to the field of production of heat-insulating building materials.

The known composition of the mixture and a method of producing foam glass, providing for the melting of glass and its grinding in a ball mill, mixing with a blowing agent and heat treatment in a foaming furnace [a.s. No. 393227, С03С 11/00, BI No. 33, 1973]. The disadvantage of the composition and method is the need for glass melting at a temperature of 1450 ° C, fine grinding of the mixture and its foaming at a temperature above 800 ° C.

A known method and composition of the mixture for producing foam glass containing (wt.%) Nepheline syenite 5-15, cullet glass containers 45-55, sodium hydroxide 7-9, perlite (volcanic glass) - the rest [Pat. RF №2164698, С03С 11/00, publ. 02/10/2001]. This composition allows you to exclude from the method the energy-intensive stage of glass melting and get foam glass from the mixture when it is heated to 750-800 ° C. The main disadvantage of this composition and method is the need for additional energy-consuming mechanochemical activation of the charge, which allows to obtain foam glass with a density of 240-841 kg / m ³ . If the charge is not mechanically activated, then foam glass with a density of 411-1023 kg / m ³ can be obtained from it.

The closest in technical essence and the achieved result is the composition and method of producing foam glass [and.with. No. 1073199, С03С 11/00, BI No. 6, 1984], including the joint grinding of perlite (volcanic glass), sedimentary siliceous rock (diatomite, tripoli, flask) and gasifier to a specific surface of 300-500 m ² / kg with the following content of components in the mixture, wt.%:

sedimentary siliceous rock - 15-70

sodium hydroxide - 6-15

gas generator - 0.02-1.5

perlite rock - the rest.

The main disadvantage of this method is the need for fine grinding of hard-to-grind pearlite rock in a medium of soft siliceous rock, which significantly reduces the grinding intensity of pearlite rock and increases the energy consumption during grinding and its duration. The main disadvantage of the composition of the charge is the rather high temperature of its foaming (800-850 ° C) and the high density of the resulting foam glass (up to 400 kg / m ³ ).

The objective of the invention is to obtain a heat-insulating material with a density of 200-300 kg / m ³ with predetermined geometric dimensions and shape, a rigid cellular structure at a foaming temperature of the charge up to 700 ° C. This object is achieved in that upon receipt of heat-insulating materials, a charge containing perlite, amorphous siliceous rock and sodium hydroxide is used, characterized in that the proposed charge contains expanded perlite with a density of 75-100 kg / m ³ according to GOST 10832-91, amorphous siliceous rock and water at the following content of components, wt.%:

Perlite expanded - twenty Amorphous Siliceous Rock - 28 Sodium hydroxide - 12 Water - 40

In addition, the task is achieved through the use of a fundamentally new method of preparing the original mixture of amorphous siliceous rock and expanded perlite. The proposed method for the production of heat-insulating material during the preparation of the charge is implemented in the following sequence: metered quantities of amorphous siliceous rock, sodium hydroxide and hot water with a temperature of 80-90 ° C are fed into a reactor with a stirrer, in which, with stirring, they form for 10-15 minutes sodium hydrosilicates in the form of a viscous liquid. Then this viscous liquid enters the intensive mixer, where it is thoroughly mixed with a metered amount of expanded perlite for 10 minutes. As a result of mixing, a mixture is obtained to obtain a heat-insulating material, which is a loose mixture with a humidity of 40%. The prepared charge in the calculated amount is loaded into a collapsible metal mold without compaction, the surface layer of the charge is leveled, the form is closed with a lid with rigid clamps and fed to a foaming furnace for heat treatment at temperatures up to 700 ° C for 0.5-1 hours. The foaming time depends on overall dimensions and volume of products. Finished products are annealed at temperatures from 700 ° C to 360 ° C for 1 h, followed by cooling in air.

The main advantage of the proposed composition of the charge is the use of amorphous siliceous rock with a particle size of 0.1-2 mm and expanded perlite with dimensions of 0.16-1.25 mm, which has a large moisture capacity, which allows to obtain a wet loose mixture from a viscous liquid. Compared with the prototype, the use of the proposed composition and method of preparation of the mixture will allow the synthesis of sodium hydrosilicates highly active with respect to expanded perlite in the presence of hot water and sodium hydroxide for 10-15 minutes at temperatures up to 100 ° C. Additional dispersion of amorphous siliceous rock occurs during its chemical interaction with sodium hydroxide and subsequent mixing of the reaction product with expanded perlite. As part of the charge of the prototype sodium hydrosilicates are not formed, because the mixture is prepared by grinding dry components and the interaction between silica and sodium oxides begins only at a temperature of more than 700 ° C. In addition, the presence of chemically bound water in the sodium hydrosilicates provides for the batch charge to be porized with the intensive removal of this water in the temperature range 500–650 ° C, which makes it possible to refuse the additional introduction of a carbonaceous blowing agent into the charge.

The main advantage of the proposed method for producing heat-insulating material is the use of a mixture with a moisture content of up to 40% and its foaming in a closed volume of a metal form.

When the mold with a wet charge is sharply heated to a temperature of more than 500 ° C, a large volume of water vapor is formed, which creates hydrothermal conditions in the charge volume, which contribute to the formation of an additional amount of hydrosilicates and sodium hydroaluminates, upon decomposition of which the charge is foamed during heating of the molds to a final temperature of 700 ° C.

The process according to the proposed method in a closed volume of the form allows you to get products with the given geometric dimensions and shape, with a thin (0.1-0.3 mm) dense vitrified crust on the surface of the products. This allows us to exclude the operation of filing them from the process of obtaining insulating products.

An example of a specific implementation.

To obtain 1 m ^{3 of} heat-insulating material with a density of 220 kg / m ³ it is necessary to take 116.67 kg of amorphous siliceous rock (flask, diatomite, tripoli), 50 kg of sodium hydroxide and 166.67 kg of hot water with a temperature of more than 90 ° C. These components are mixed for 10 minutes, resulting in the formation of sodium hydrosilicate, which is then thoroughly mixed with 83.34 kg of expanded perlite. The resulting mixture with a moisture content of 40% is loaded into a collapsible metal mold, the inner surface of which is preliminarily lubricated with clay-lime or clay-gypsum suspension to prevent sticking to the mold. The estimated amount of charge loaded into the form is determined by the formula:

m = 1,894 · p · V, kg,

where 1,894 - coefficient taking into account the loss of moisture during heat treatment of the mixture;

p is the specified density of the insulating material, kg / m ³ ;

V is the volume of the form, m ³ .

The loaded charge in the mold is leveled in the surface layer, the mold is closed with a lid with clamps and placed in a muffle furnace previously heated to a temperature of 500 ° C. Further heating of the mold to a final temperature of 700 ° C is carried out for 30 minutes, after which the furnace is turned off and the mold with the product is cooled to a temperature of 360 ° C for one hour. After that, the mold is removed from the furnace and cooled in air for 30 minutes to a temperature of 50-60 ° C, the product is disassembled and the product is removed from it, from which all the necessary parameters are determined.

It should be noted that all products had a clear geometric shape and dimensions, and their surface was covered with a solid vitrified crust with a thickness of 0.1-0.3 mm. The size of the obtained products 10 × 10 × 5 cm ³ , the volume is 500 cm ³ .

By this method, products with a density in the range of 200-300 kg / m ³ with a step of 20 kg / m ³ were manufactured. The estimated quantities of the components of the mixture to obtain products with a given density and their properties are presented in the table, from which it follows that the use of the proposed composition of the mixture and method allows to obtain heat-insulating materials with properties superior to the properties of materials obtained from known compositions by known methods.

The proposed technical solution in comparison with the known methods and compositions used in the technology of thermal insulation materials, has a significant advantage, among which it is necessary to highlight the following:

- simplifies the technology of obtaining insulating material;

- the energy-consuming stage of high-temperature glass melting is excluded from the process;

- excludes the operation of fine grinding of the components of the mixture;

- the activation of the charge is carried out not by a mechanical, but by a chemical method;

- expanded perlite is used more effectively in comparison with, for example, the production of cement-perlite products;

- significantly reduced temperature and foaming time of the mixture and the time of annealing of products;

- the blocks do not require filing and are obtained with the given geometric shape and dimensions.

Obtained by the proposed technical solution thermal insulation products can be used for thermal insulation of various construction projects, power plants and pipeline transport.

Table A method of obtaining a heat-insulating material and a mixture for its manufacture Charge components and product properties Consumption of charge components per 1 m ³ foam glass (kg), heat treatment mode and product properties indicators one 2 3 four 5 6 Expanded perlite, kg 75.76 83.34 90.91 98.49 106.06 113.64 Amorphous siliceous rock, kg Tripoli 106.06 flask 116.67 diatomite 127.27 tripoli 137.88 flask 148.50 diatomite 159.09 Sodium hydroxide, kg 45.46 50.00 54.55 59.09 63.63 68.18 Water kg 151.52 166.67 181.82 196.98 212.13 227.28 Foaming temperature range, ° С 700 700 700 700 700 700 Foaming time, h 0.5 0.5 0.5 0.5 0.5 0.5 The density of products, kg / m ³ 200 220 240 260 280 300 Compressive strength, MPa 1.44 1,62 1.88 2.14 2.48 2.67 The coefficient of thermal conductivity, W / (m · deg) 0,062 0,068 0,074 0,079 0,083 0,086

Claims (2)

1. A method of obtaining a heat-insulating material, including dosing of charge components, their dispersion, foaming of the charge and annealing of products, characterized in that the charge components are used in the initial dispersed state, pre-amorphous siliceous rock, sodium hydroxide and hot water with a temperature of 80-90 ° C stirred in the reactor for 10-15 minutes to form sodium hydrosilicate, then the resulting liquid is mixed with expanded perlite for 10 minutes, and the foaming of the mixture is carried out in a closed meta in the form of a liquid at temperatures up to 700 ° C for 0.5-1 h, and the finished products are annealed at temperatures from 700 ° C to 360 ° C for 1 h, followed by their cooling in air. 2. The mixture for the manufacture of heat-insulating material, including perlite, a siliceous component and sodium hydroxide, characterized in that it contains expanded perlite with a density of 75-100 kg / m ³ , amorphous siliceous rock and water in the following ratio of components, wt.%:
Expanded perlite twenty Amorphous Siliceous Rock 28 Sodium hydroxide 12 Water 40