RU2405743C1 - Crude mixture for producing foamed silicate material and method of producing foamed silicate material (versions) - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to foaming compositions based on magmatic aluminosilicate rock, particularly to production of foamed silicate heat insulation material. The crude mixture for producing foamed silicate material, which contains magmatic rock and a gas-forming agent, contains magmatic rock containing 40-75 wt % SiO₂, zeolite-containing tuff as a gas-forming agent, as well as flux which contains 40-84 wt % Na₂O or K₂O, with the following ratio of components, wt %: said rock 45.0-77.0, said flux 8.0-15.0, zeolite-containing tuff 15.0-40.0. The method of producing foamed silicate material involves preparation of the said crude mixture by mixing its components, moistening with an aqueous solution of liquid glass with density of 1.15-1.3 g/cm³ in ratio solid: liquid equal to 1.4-1.9, moulding granules, drying and expanding the granules by burning at 700-900°C. In another version, granules are prepared by seasoning the crude mixture until solidification and then crushing the hardened mass. In both versions of the method, expansion is carried out in moulds or in free state.

EFFECT: low power consumption, production of foamed silicate materials with wide range of density.

7 cl, 2 tbl, 12 ex

Description

The invention relates to expandable compositions based on magmatic aluminosilicate rocks, intended for the production of foam silicate thermal insulation material - an analogue of foam glass. It can be used for the production of lightweight silicate materials, used as independent building materials in the supporting elements of buildings with heat-insulating and sound-insulating properties, as heat-insulating material, and also as a lightweight concrete aggregate.

It is known that block and granular building foam silicate material (foam glass) is made from a mixture of finely ground glass (specially welded or battle) and a gasifier or from mixtures of finely ground natural aluminosilicate rocks with technological additives without preliminary boiling of glass from them.

Various compositions are known for the manufacture of block foam silicate material (foam glass) from finely divided glass when carbon-containing materials are used as a gasifier: graphite, coal, soot, silicon carbide, etc., or carbonate materials [F. Schill. Foam glass (production and use) - M .: Publishing house of building literature, 1965, p. 53], or a composition of carbon-containing and carbonate materials [RF Patent No. 2291125, IPC S03C 11/00]. The manufacturing process of block foam silicate material (foam glass) consists of finely grinding specially welded or glass breaking, mixing with a gas-generating substance, filling the mixture of powders into a heat-resistant form, foaming the block, annealing and cooling it.

Various compositions are known for the manufacture of a porous aggregate in concrete, granular foam silicate material (granular foam glass), when an additional binder solution, for example milk of lime, is added to a mixture of powders of glass waste and a blowing agent [RF Patent No. 2109700, IPC С03С 11/00]. To make a porous filler, the foaming powder mixture is moistened with a binder solution, raw granules are prepared from the wet mass, which are then dried, foamed and cooled.

The disadvantages of the known compositions for the manufacture of both block and granular foam silicate materials from finely ground specially welded glass or from glass breakage are:

- high energy consumption during special glass melting, which is carried out at 1400-1450 ° C;

- a direct dependence of the production of foam glass on the volume of industrial and household waste glass if used as the main source of raw materials. Insignificant volumes of glass waste in most regions of Russia do not allow launching production data;

- high energy costs due to the high foaming temperature of the compositions on the basis of glass breakdown and carbonaceous blowing agents, which, as a rule, is not lower than 850 ° C;

- the absence of methods for manufacturing from the same composition of the raw mix of both block and granular foam.

Known compositions of raw mixtures and methods for manufacturing both a porous aggregate in concrete and a block heat-insulating foam silicate material from aluminosilicate rocks without their preliminary melting into glass.

The most common aluminosilicate raw material for the manufacture of porous aggregate (expanded clay) is intumescent low-melting clay. On the territory of Russia there are few well-expanding clays, therefore expanded clay gravel is produced, as a rule, with a bulk density of more than 600 kg / m ³ , which does not allow to achieve a good heat-insulating effect in building structures. A decrease in expanded clay density is achieved by introducing special technological additives into the composition. For example, the known raw material mixture for the manufacture of expanded clay with a bulk density of 280-400 kg / m ³ containing, wt.%: Clay raw materials - 84-95; oil sludge - 4-6; Surfactant (waste alkalization of diesel fuel) - 1-10 [RF Patent No. 2287499, IPC С04В 14/12].

The disadvantages of the compositions for the manufacture of expanded clay and the known solutions in particular are the following:

- high firing temperature (1100 ° C and above);

- for the manufacture of expanded clay with reduced bulk density, special technological additives are required, the supply volumes of which are not guaranteed;

- expanded clay porous structure is characterized by large uneven porosity with a large number of open pores. This determines lower values of mechanical strength and high rates of water absorption;

- Clays of the majority of Russian deposits are not suitable for expanded clay production due to high sand content.

Known compositions of the mixture for the manufacture of block foam silicate material (foam glass) using aluminosilicate rocks without their preliminary melting into glass, including, wt.%: Nepheline syenite - 5-15; glass container fight 45-55; sodium hydroxide hydrate - 7-9, volcanic glass - the rest [RF Patent No. 2148898, IPC С03С 11/00]. Such a mixture does not include a special foaming gas-generating substance, and the foaming gas is water vapor formed at high temperatures due to the condensation of chemically bound water - Si-OH groups formed in natural aluminosilicates during their mechanical activation.

The disadvantages of such a mixture for the manufacture of block foam glass are:

- high energy consumption for the mechanical activation of the solid components of the mixture after fine grinding. Mechanoactivation is necessary for the formation of Si-OH siloxane groups, due to which high-temperature evolution of water vapor and foaming of the charge are carried out;

- low content in the composition of the charge of magmatic aluminosilicate rock - nepheline syenite, comprising 5-15 wt.%;

- the use of perlite is envisaged as volcanic glass, which in Russia is represented mainly by one Mukhor-Talinsky deposit in the Republic of Buryatia, and the European part of Russia does not have perlite deposits;

- high content of battle of container glass in the composition of the charge - 43-55 wt.%;

- use only hydrated sodium hydroxide (NaOH) as a flux, which is an environmentally unsafe substance;

- according to the known composition of the charge provides for the production of only block foam.

The development of industrial processes currently requires an integrated approach to create production of building materials. At the same time, raw materials should be widespread, and technology should ensure the manufacture of a wide range of products. Widespread aluminosilicate rocks include igneous rocks. In terms of SiO ₂ content, igneous rocks are subdivided into ultrabasic (SiO _{2 -} 40%), basic (SiO ₂ 40-55%), medium (SiO ₂ 55-65%), acid (SiO ₂ 65-75%) and other types of igneous rocks. The natural melting temperature of igneous rocks with a SiO ₂ content _of 40-75 wt.% Is in the range of 1100-1250 ° C, which is close to the melting temperature of intumescent clays used for the production of expanded clay.

By the nature of occurrence, igneous rocks are divided into deep (intrusive) and outflowing (extrusive) with surface occurrence. The chemical composition of deep and surface igneous rocks is identical and can equally be used in the production of foam silicate materials. However, surface (poured) rocks are more preferable due to the simplicity of quarrying of such deposits. In addition, magma, which poured onto the earth's surface in the form of lava flows, quickly hardens, therefore, such rocks have a fine crystalline structure and contain a significant amount of the glassy phase, which facilitates its melting.

Igneous rocks are widely used to obtain crushed stone. After sieving the crushed rock to obtain productive crushed stone, screenings (small fraction of less than 5 mm) are practically not used at many quarries and remain in the form of embankments in the quarry, which creates an technogenic adverse environmental load in the quarry. Since the chemical composition of screenings is similar to the chemical composition of the main rock, crushing screenings can be used along with the main rock in the production of foam silicate foams.

Unlike intumescent clays, igneous rocks do not contain compounds capable of forming a high-temperature gas phase in the region of rock melting temperature, therefore gas-forming substances must be specially introduced into the composition of the raw material mixture. Conventional carbonaceous blowing agents, such as coke, coal, graphite, which are traditionally used for the manufacture of foam silicate materials such as foam glass, cannot be used for the manufacture of similar foam silicate materials from igneous rocks. Igneous rocks are characterized by a high melting point (above 1100 ° C), therefore carbonaceous blowing agents burn out from the surface. The only carbon-containing blowing agent that does not fade to the melting temperature of igneous rocks is silicon carbide (SiC) or materials containing it. This limited the possibility of using magmatic aluminosilicate raw materials for the production of porous structural and heat-insulating materials.

The closest analogue of the proposed raw material mixture and the method of manufacturing foam silicate materials from it is a raw material mixture for the manufacture of a porous aggregate, including screenings from crushing diorites and a gasifier, which is used as silicon carbide, in the following ratio of components, wt.%: Screenings from crushing diorites - 99.5-99.8; a blowing agent is 0.2-0.5, and a method of manufacturing a porous silicate material from it, including grinding screenings from crushing diorites to passing through a sieve 008 no more than 5 wt.%, mixing with a blowing agent - silicon carbide, moistening the mixture of powders to a moisture content 16-17%, the preparation of raw granules from a wet mass by plastic molding, drying of raw granules at 100 ° C for 30 minutes and foaming of the granules by firing at a temperature of 1156-1190 ° C for 10 minutes [RF Patent No. 1730075, IPC С04В 18/04]. These raw mix and method of manufacturing a porous aggregate from it are taken as a prototype of an application for invention.

The disadvantages of the prototype are:

- high melting temperature of the composition and pore formation in granules - 1156-1190 ° C;

- provides for the use of only screenings and only one type of magmatic aluminosilicate raw material - diorite rocks, while for large-scale production of foam silicate materials of a wide range of purposes, it is advisable to focus not only on screenings, but also on the breed of a wide range of igneous rocks;

- use of silicon carbide (SiC) as a blowing agent, which is produced in Russia by one plant (Volzhsky Abrasive Plant). Silicon carbide is an expensive and severely scarce material;

- only one type of porous silicate product can be made from the specified raw material mixture - a porous aggregate with a small range of bulk density (250-300 kg / m ³ ).

The proposed invention solves the problem of expanding the raw material base for the production of foam silicate materials through the use of a wide range of aluminosilicate igneous rocks as raw materials, such as basalts, andesites, diorites, granites, syenites, porphyrite and vitrophyric rocks, tuff rocks and other igneous rocks containing SiO ₂ , equal to 40-75 wt.%, and also solves the problem of creating methods for the manufacture of foam silicate materials for a wide range of purposes - block and granular (porous fillers) from one composition of the raw mix.

The technical result of the invention is to reduce the melting temperature of the raw material mixture to 700-900 ° C, which reduces the energy consumption for the production of foam silicate materials and allows the widespread aluminosilicate rock with water-containing zeolite crystals - zeolite-containing tuffs to be used as a gasifier, thereby ensuring environmental safety of production. The technical result of the invention is also the possibility of manufacturing foam silicate materials with a wide density range through the use of a wide range of aluminosilicate igneous rocks with a SiO ₂ concentration range of 40-75 wt.%, Which ensures the formation in the temperature range of foaming of both low-viscosity and high-viscosity melts, leading to the formation of a porous material with a significantly different degree of development of the porous system in the foam silicate material and, therefore, with different product density.

The problem is solved in that a raw material mixture is proposed for the manufacture of foam silicate materials, which includes igneous rock with a SiO ₂ content of 40-75 wt.%, As a blowing agent - zeolite-containing tuff and, optionally, fluff containing 40-84 wt.% Na ₂ O or K ₂ O, in the following ratio of components, wt.%:

specified breed 45.0-77.0 specified melt 8.0-15.0 zeolite-containing tuff 15.0-40.0

The problem is also achieved by the fact that the method of manufacturing a foam silicate material involves preparing a raw mixture of the specified composition by mixing its components, moistening the raw mixture with an aqueous solution of liquid glass with a density of 1.15-1.3 g / cm ³ in the ratio solid: liquid 1.4- 1.9, production of granules, drying and foaming of granules by firing at a temperature of 700-900 ° C. In this case, the granules are made by molding the raw material mixture or by curing the moistened raw material mixture before hardening, followed by crushing the hardened mass.

Additional differences are also that the foaming of granules obtained both by molding and by aging the moistened mass before hardening, followed by crushing of the hardened mass, is carried out in heat-resistant forms or in a free state.

As igneous rocks, it is proposed to use igneous rocks with a SiO ₂ content of 40-75 wt.%. These are basalts, diabases, syenites, porphyritic and vitrophyric rocks, andesites, tuff rocks and any other rocks of this group, as well as screenings from crushing of these igneous rocks, as screenings have the same mineral and chemical composition as the main breed.

The claimed range of SiO ₂ concentrations (40-75%) in igneous rocks characterizes almost all the main igneous rocks. Such rocks should be predominantly silicate to form a sufficient amount of silicate melt capable of pore formation and the formation of foam silicate material. When the concentration of SiO _{2 is} less than 40% of the silicate melt, it is not enough that pores are formed during the evolution of gases. The restriction on the upper limit of the SiO ₂ content of 75% is due to the fact that in igneous rocks this is the upper limit of the SiO ₂ concentration.

The restriction on the content of igneous rock in the composition of the raw mix is due to the optimal ratio in the composition of the raw mix. If the igneous rock content in the raw material mixture is less than 45%, the melt will not be enough for the formation of a porous structure, and if the concentration is more than 77% in the temperature range of the firing, the melt will either not form at all, or it will have a high viscosity at which pores do not form.

As fluxes, soda ash, sodium hydroxide or potassium hydroxide, chemical waste containing elements of alkali metals and other alkali-containing materials can be used. The percentage of Na ₂ O or K ₂ O in them must correspond to that indicated in the composition of the raw material mixture. So, when the concentration of Na ₂ O or K ₂ O in the smooth is less than 40% in the indicated temperature range of firing, the melt necessary for pore formation is not formed. The upper limit of the concentration of Na ₂ O or K ₂ O in the flux is due to its maximum concentration in one of the possible flooded fluids - KOH, in which K ₂ O is 84%.

Limitations on the content of igneous rock and fluxes in the raw material mixture are due to their optimal ratio, at which low-temperature eutectic melts are formed with the transition of the entire mass to the pyroplastic state in the temperature range of 700-900 ° С.

It is proposed to use zeolite-containing rock as a blowing agent in this temperature range for the production of foam silicate materials. In this case, when the temperatures of low-melting eutectics (700-900 ° C) are reached, pore formation is carried out due to the release of residual zeolite water into the gas phase and the creation of excessive pressure in the micropores of the molten composition. Zeolites in tuffs lose zeolite water in the temperature range of 100-600 (700) ° C. The raw material mixture of this composition, moistened with an aqueous solution of water glass, hardens to a stone-like state when aged and dried. From dense, solidified granules, the removal of zeolite water (molecular and chemically bound) slows down and it remains in the required amount to temperatures of 700-900 ° C, at which the aluminosilicate components of the granules are melted and the gases released are encapsulated in micropores. Due to the pressure of the released water vapor, the micropores expand, forming a porous system in the molten glass.

Limitations of the concentration of zeolite-containing tuff in the composition of the raw material mixture are due to a sufficient level of gas phase concentration for the formation of foam silicate materials with a density of block foam silicate material of 200-800 kg / m ³ and a porous aggregate with a bulk density of 120-450 kg / m ³ .

To moisten the prepared raw mix of powders, an aqueous solution of liquid glass with a density of 1.15-1.3 g / cm ³ with a ratio of solid: liquid equal to 1.4-1.9 is used. In addition to the humidifier, an aqueous solution of water glass is a binder that forms the forming mass, and after aging and drying, forms dense, durable raw billets with aluminosilicate components of the composition. In this regard, granules can be prepared by conventional plastic molding of a raw mixture moistened with an aqueous solution of liquid glass, followed by drying of the granules or by aging the moistened mixture until it solidifies with crushing of the solidified mass and subsequent drying of the granules. Plastic molding can be carried out on any type of equipment (plate granulator, rollers, hole granulator, etc.). The crushing of the hardened moistened raw material mixture can be carried out on any crushing units - jaw crushers, rollers and any others that allow to obtain granules of the desired size.

The concentration limits of water glass in the mixture are due to the molding and binding properties of the wet mass. When the ratio is solid: liquid less than 1.4, the mass is waterlogged, sticks to contacting surfaces and is poorly formed. In addition, the high consumption of liquid glass is not economically viable. With a solid: liquid ratio of more than 1.9, the mass is poorly moistened and does not form. Such a mass during aging hardens unevenly with loose crumbling areas, which does not allow granules to be produced by crushing the hardened mass.

The density limit of an aqueous liquid glass solution of 1.15-1.3 g / cm ³ is due to manufacturing expediency. Technical liquid glass according to GOST 13078-81 is available with a density of 1.35-1.52 g / cm ³ . Such liquid glass is too thick to knead a dry mixture, so it is diluted with water to the specified limiting values. When the density of the aqueous liquid glass solution is higher than 1.3 g / cm ^{3, the} dry mixture is poorly kneaded. At a density of less than 1.15 g / cm ^{3, an} aqueous solution of liquid glass has low binding properties, the moistened mass is poorly molded, and hardens poorly when aged.

From the prepared and dried granules, it is possible to produce both block foam silicate material and granular. When foaming the granules by firing in a confined space in heat-resistant forms, block foam silicate material is obtained. When firing the granules in a free state, when the individual granules are separated by a space that prevents them from sticking together during foaming, granular foam silicate material is obtained.

The temperature range of the firing is limited by the fact that at a temperature below 700 ° C the granules do not foam, since at such temperatures eutectic melts do not form and the granules do not acquire a pyroplastic state. The released vapors of zeolite water in this case go into the atmosphere. At temperatures above 900 ° C, the concentration of residual zeolite water is significantly reduced, which dramatically reduces the intensity of foaming of the granules.

The claimed range of foaming temperatures of 700-900 ° C makes it possible to produce foam silicate material with a minimum density, namely, block foam glass - 200 kg / m ³ , granular foam silicate material with a bulk density - 120 kg / m ³ , and heavier - block with a density not more than 800 kg / m ³ , and granular - with a bulk density of not more than 450 kg / m ³ , as well as any intermediate varieties thereof.

A wide range of density of foam silicate material allows you to expand the scope of its use. Light types of block products can be used as highly efficient, environmentally friendly, non-combustible, durable heat-insulating material in various fields of construction and industry.

Heavier heat-insulating block products can be used in load-bearing elements in buildings. The use of granular foam silicate material can also vary depending on its bulk density.

The solution proposed in the invention is environmentally friendly, since the only gas emitted during the firing of the raw material mixture is water vapor, which is released due to the dehydration of zeolite crystals in zeolite-containing tuffs. In modern conditions of limiting CO ₂ emissions into the atmosphere, the proposed solution for the manufacture of aluminosilicate foams is relevant.

Penosilicate material from the proposed compositions of the raw mix is made as follows.

Examples of specific performance.

Igneous rock or screenings from its crushing is crushed in a ball or any other mill until no more than 5 wt.% Pass through a 008 sieve. The crushed powder of igneous rock is mixed with pre-crushed 0.25 zeolite-containing tuff before passing through a sieve and smoothly. An aqueous solution of liquid glass with a density of 1.15-1.3 g / cm ³ with a ratio of solid: liquid = 1.4-1.9 is added to the dry powder mixture and mixed until a homogeneous plastic mass is obtained. The quantitative proportions of the components included in the raw mix must correspond to those indicated in the composition of the raw mix. From a moistened raw material mixture, granules are prepared in any of two ways.

Option 1. Granules of the required size are made from the wet mass by plastic molding, then the granules are dried to an air-dry state at 100-450 ° C.

Option 2. Wet raw mass is aged in the atmosphere of the workshop before hardening, after hardening it is crushed in a jaw or any other crusher, then it is dried to an air-dry state at a temperature of 100-450 ° C.

Granular foam silicate (porous aggregate) is obtained by roasting granules made by any of the claimed methods in any furnace at a temperature of 700-900 ° C, the roasting method in which does not allow the granules to stick together when foaming. It can be ring furnaces with a moving hearth, shaft, rotary, tunnel and any other furnace, ensuring non-sticking of individual granules to each other.

To obtain a block of foam silicate material, granules made by any of the claimed methods are poured into heat-resistant forms. Heating to a maximum temperature of 700-900 ° C is carried out in 1.5-3 hours. The exposure of the form with granules at a firing temperature is 20-60 minutes Block foam-silicate material after foaming is annealed according to the generally accepted method of annealing foam-glass material.

Specific parameters for the manufacture of granular foam silicate material from a mixture of various compositions are shown in table 1, and block - in table 2.

Claims (7)

1. The raw material mixture for the manufacture of foam silicate material, including igneous rock and a blowing agent, characterized in that it contains igneous rock with a content of SiO _{2 of} 40-75 wt.%, As a blowing agent - zeolite-containing tuff and optionally melt containing 40-84 wt.% Na ₂ O or K ₂ O, in the following ratio of components, wt.%:
specified breed 45.0-77.0 specified melt 8.0-15.0 zeolite-containing tuff 15.0-40.0 2. A method of manufacturing a foam silicate material, comprising preparing a raw material mixture according to claim 1 by mixing its components, moistening the raw mixture with an aqueous solution of water glass with a density of 1.15-1.3 g / cm ³ in the ratio solid: liquid 1.4-1, 9, the manufacture of granules by molding, drying and foaming of the granules by firing at a temperature of 700-900 ° C. 3. The method according to claim 2, characterized in that the foaming is carried out in forms. 4. The method according to claim 2, characterized in that the foaming is carried out in a free state. 5. A method of manufacturing a foam silicate material, comprising preparing a raw mixture according to claim 1 by mixing its components, moistening the raw mixture with an aqueous solution of liquid glass with a density of 1.15-1.3 g / cm ³ in the ratio solid: liquid 1.4-1, 9, the manufacture of granules by aging the moistened raw material mixture before hardening, followed by crushing the hardened mass, drying and foaming of the granules by calcination at a temperature of 700-900 ° C. 6. The method according to claim 5, characterized in that the foaming is carried out in forms. 7. The method according to claim 5, characterized in that the foaming is carried out in a free state.