RU2476407C2 - Raw mixture for manufacturing thermal insulation - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to construction materials, namely to raw mixtures for manufacturing thermal insulation, applied in industrial thermal units of various purposes. Raw mixture for manufacturing thermal insulation, which includes binding agent, swollen vermiculite and fibrous filling agent, as binding agent it contains Portland cement, and as fibrous filling agent - basalt fibre, additionally it contains microsilica and complex additive - modified hydroxyethylcellulose, with the following component ratio, wt %: Portland cement 46-53, swollen vermiculite 21-25, basalt fibre 16-21, microsilica 8-10, and complex additive (modified hydroxyethylcellulose) 0.4-07 of binding agent weight.

EFFECT: reduction of thermal conductivity, increase of thermal stability of thermal insulation and reduction of its linear temperature shrinkage at maximal temperature of exploitation.

2 tbl

Description

The invention relates to building materials, namely to raw mixes for the manufacture of thermal insulation used in industrial thermal units for various purposes.

Known raw mix for the manufacture of thermal insulation by shotcreting, including a binder - water glass, hardener, aggregate - expanded clay sand and expanded vermiculite (preheated at a temperature of 300-350 ° C), in the following ratio of components, wt.%:

liquid glass 2-8 hardener 3-10 expanded clay sand 10-30 vermiculite (preheated at a temperature of 300-350 ° C) 52-85

(see Pat. RU No. 722882 of 03/02/1978, publ. 25.03.1980).

The volume of the insulating layer based on this raw material mixture when exposed to temperatures above 350 ° C increases due to the expansion of vermiculite ore, which often leads to its cracking and destruction, which is the main disadvantage of this mixture.

Also known is the raw material mixture for the manufacture of thermal insulation by shotcreting or forming, including a binder - water glass, a fibrous aggregate - asbestos waste, expanded vermiculite and a finely ground fuel ash and slag mixture, in the following ratio, wt.%:

liquid glass 25-32 asbestos waste 41-55 expanded vermiculite 3-6 finely ground fuel ash and slag mixture 17-21

(see Pat. RU No. 1203059 from 07/05/1984, publ. 07/01/1986).

The disadvantage of this mixture is the relatively low temperature of its use (not higher than 600 ° C), insufficiently high heat resistance and significant (up to 2%) linear shrinkage at the maximum temperature of application.

The closest in technical essence to the claimed raw material mixture for the manufacture of thermal insulation is a raw material mixture for the manufacture of thermal insulation (thermal insulation products), including a binder - liquid glass and clay, expanded vermiculite and fibrous aggregate (fiberglass), in the following ratio, wt.%:

fiberglass 70-80 clay 5-15 expanded vermiculite 5-10 liquid glass 5-10

(see Pat. RU No. 2104252 from 01.24.1996, publ. 02.10.1998).

The disadvantage of this mixture is a sufficiently high thermal conductivity of the material, its low thermal stability and significant linear shrinkage at the maximum operating temperature.

The technical result of the invention is to reduce thermal conductivity, increase the thermal stability of thermal insulation and reduce its linear temperature shrinkage at maximum operating temperature.

The technical result is achieved in that the raw material mixture for the manufacture of thermal insulation, including a binder, expanded vermiculite and a fibrous aggregate, according to the invention contains Portland cement as a binder, basalt fiber as a filler, additionally contains silica fume and a complex additive - modified hydroxyethyl cellulose, in the following the ratio of components, wt.%:

binder (portland cement) 46-53 expanded vermiculite 21-25 basalt fiber 16-21 silica fume 8-10

and the complex additive - modified hydroxyethyl cellulose - 0.4-07 by weight of the binder.

The proposed raw material mixture for the manufacture of thermal insulation extends the range of thermal insulation and provides improved performance of thermal insulation achieved by the entire combination of components and their ratio in accordance with the distinctive features of the claims, namely: increasing the thermal stability of thermal insulation, as well as reducing thermal conductivity and reducing linear temperature shrinkage when maximum operating temperature.

Introduction to the proposed raw material mass of basalt fiber, silica fume and a complex additive - modified hydroxyethyl cellulose contributes to the creation of a disperse-reinforced matrix with increased thermal shock resistance in the granular-fibrous structure of the heat-insulating material and at the same time increasing its heat transfer resistance.

The patent studies did not reveal similar technical solutions, which allows us to conclude about the novelty and inventive step of the claimed technical solution.

The domestic industry has all the means (materials, equipment and technology) necessary to obtain the proposed raw material mixture for the manufacture of thermal insulation and its widespread use in industry for high-temperature thermal insulation in thermal units for various purposes with an insulated surface temperature of up to 900 ° C.

The essence of the claimed invention is illustrated by experiments and the results obtained.

The raw material mixture for the manufacture of thermal insulation contains: a binder - Portland cement (GOST 10178-85), expanded vermiculite (GOST 12865-67), a fibrous filler - basalt fiber, silica fume and a complex additive - modified hydroxyethyl cellulose, in the following ratio, wt.%:

binder (portland cement) 46-53 expanded vermiculite 21-25 basalt fiber 16-21 silica fume 8-10

and the complex additive - modified hydroxyethyl cellulose - 0.4-07 by weight of the binder.

Fibrous aggregate - basalt fiber (TU 5952-036-05328981-2005 "Basalt chopped thread") - has the following technical characteristics:

single fiber diameter, microns 13-17 fiber length mm 0.6-1 mass fraction of oiling, not more than,% 0.3 mass fraction of moisture, not more than,% one hygroscopicity not more than,% 2 content of substances removed during calcination, not more than,% 0.3

The characteristic properties of basalt fiber are:

- environmental cleanliness;

- resistance to aggressive environments;

- high strength and durability;

- absolute incombustibility.

Silica fume is a finely dispersed product formed during the production of silicon-containing alloys and is a silica of amorphous modification. Silica fume is produced in accordance with TU 5743-048-02495332-96 and has the following technical characteristics:

bulk density, kg / m ³ 110-120 humidity% 3 loss on ignition,% 1,58 activity index,% 110 SiO ₂ content, 84.9-86.2 CaO content 0.75-0.78

The complex additive - modified hydroxyethyl cellulose - is a product obtained by processing natural organic raw materials, ground into powder and mixed with sodium liquor and then esterified with methyl chloride and ethylene oxide.

Thus, the basis of the modified hydroxyethyl cellulose is ethyl cellulose [(C ₆ H ₇ O ₀₂ (OH) ₃ OS ₂ H ₅ ) _X ] _n . The exact composition of this product is know-how.

During the experiments, the components for obtaining the raw mix were taken in the ratio, wt.%, Indicated in table 1.

Table 1 Components The number of the composition and the content of the components in the ratio, wt.% one 2 3 Binder - Portland cement M 400 46 49.5 53 Expanded Vermiculite 25 23 21 Basalt fiber 21 18.5 16 Silica fume 8 9 10 Complex additive - modified hydroxyethyl cellulose (by weight of the binder) 0.4 0.55 0.7

The raw material mixture for the manufacture of thermal insulation is prepared as follows. A metered amount of Portland cement binder M 400, silica fume and modified hydroxyethyl cellulose are introduced into the mixer, then expanded vermiculite and basalt fiber are introduced. After that, the required amount of water is supplied to the mixer. The required amount of mixing water is on average 960 liters per 1 ton of dry mix, which corresponds to a water-cement ratio in the range of 2.20-2.25. This is explained by the high content of porous (expanded vermiculite) and fibrous (basalt fiber) aggregates in the initial raw material mixture. Mixing is continued until a homogeneous (homogeneous) mass is obtained.

The main properties of thermal insulation based on the proposed raw material mixtures are shown in table 2.

table 2 The properties Composition number and property indicators one 2 3 The density of the material, kg / m ³ 310 315 320 Thermal resistance (number of cycles of air heat exchanges) 25 ± 5 ° С - 800 ° С 95 116 127 Linear temperature shrinkage at Т = 800 ° С 0.10 0.27 0.16 Thermal conductivity at T = 600 ° C, W / m · K 0,110 0.132 1.51 Application temperature, ° С 900 900 900

The raw material mixture for the manufacture of thermal insulation provides:

the density of the material, kg / m ³ 310-320 thermal stability (number of cycles of air heat exchanges) 25 ± 5 ° С-800 ° С 95-127 linear temperature shrinkage at Т = 900 ° С 0.1-0.16 thermal conductivity at T = 600 ° C, W / m · K 0,110-0,151 application temperature, ° С 900

A decrease in the binder content of less than 46% does not provide the necessary strength characteristics of the material, and an increase in its content over 53% leads to an increase in the average density of the material and an increase in thermal conductivity.

A decrease in the content of expanded vermiculite of less than 21% leads to a decrease in the thermal stability of thermal insulation, and an increase in its content in excess of 25% does not make it possible to produce a coating of the claimed properties.

A decrease in the raw mix for the manufacture of thermal insulation of basalt fiber content of less than 16% leads to an increase in the linear temperature shrinkage of the material, and an increase of more than 21% leads to a decrease in the strength characteristics of the material.

A decrease in silica fume content of less than 8% leads to an increase in linear temperature shrinkage, and an increase in its content of more than 10% leads to a decrease in the thermal stability of the material.

A decrease in the content of modified hydroxyethyl cellulose of less than 0.4% by weight of the binder leads to a decrease in the thermal stability of the material, and an increase in its content of more than 0.7% leads to an increase in the linear temperature shrinkage of the material.

Tests of the proposed raw mix were carried out in the manufacture of thermal insulation of high-altitude metal chimneys.

Claims (1)

The raw material mixture for the manufacture of thermal insulation, including a binder, expanded vermiculite and a fibrous filler, characterized in that it contains Portland cement as a binder, basalt fiber as a fibrous filler, additionally contains silica fume and a complex additive - modified hydroxyethyl cellulose in the following ratio of components, wt. %:
Portland cement binder 46-53 expanded vermiculite 21-25 basalt fiber 16-21 silica fume 8-10 complex additive - modified hydroxyethyl cellulose 0.4-07 by weight of the binder