RU2572437C1 - Complex technological line for production of granulated porous material from siliceous raw material - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: composition of complex technological line includes constructive elements, interaction in one continuously operating technological line with installed successively and in parallel way receiving hopper-batcher of siliceous raw material, crusher, equipment for fine crushing and mechanical activation of raw material, hopper-batcher of prepared raw material, hopper-batcher of gas-generator, hopper-batcher of alkali component, mixer-granulator, drier, foaming furnace, device for discharge of flue gases, hopper-batcher of separating medium, classifier and finished product warehouse.

EFFECT: obtaining light heat-insulating granulated porous material from siliceous raw material with different content of chemically active amorphous silica.

3 tbl, 1 dwg

Description

The complex technological line for the production of granular porous material from siliceous raw materials relates to the production of building materials, namely, to the production of light heat-insulating granular porous fireproof cellular materials with a silicate base. Porous material obtained from natural raw materials is a type of foam glass and can be used in various fields of construction as bulk heat and sound insulating material in the ceilings of buildings, in basements, in road construction, as well as as light fillers in concrete, plasters, dry construction and grouting mixtures and in other areas of construction.

Foam glass, block or granular, is obtained by firing at a melting temperature of a mixture of glass powder, specially welded or glass broken, with blowing agents. Despite the high operational characteristics of granular foam glass, there are few enterprises producing it in Russia. This is due to the high energy costs of special glass melting (1450 ° C) and the limited glass breakage. Therefore, methods, compositions and production lines for the production of granular porous inorganic materials in which glass is replaced with natural silicate raw materials without preliminary melting are being developed.

The solid phase of porous materials from natural siliceous raw materials, in contrast to foam glass from glass, in addition to the glass phase, contains a crystalline phase. Such porous material in publications and in the patent literature is denoted by various terms: foam glass such as foam glass [1], foam ceramic [2], foam silicate [3] or the general term is porous material [4].

The most suitable and widespread silicate raw materials for the manufacture of inorganic porous materials are siliceous rocks (flask, tripoli, diatomite, etc. similar). To reduce the melting point of natural raw materials, melts are introduced into the compositions, which are used as sodium hydroxide or potassium hydroxide (common names are alkali or caustic soda). Alkali in the form of an aqueous solution is mixed with crushed rock. When using other floodplains (soda ash, borax, etc.) in the compositions based on siliceous rocks, pore formation does not occur. This is due to the fact that, in addition to the fluxing effect during firing, the alkali dissolved in water, when mixed with siliceous powder, interacts with amorphous silica to form hydrated sodium polysilicates (water glass), which are a source of pore-forming gases (water vapor). The manufacture of granular porous materials from siliceous rocks with sodium hydroxide as fluff is carried out on the specialized technological lines developed for this [2-4].

The main disadvantage of the known technologies and technological lines for the production of granular porous materials based on siliceous rocks is the dependence of the rate of pore formation and, consequently, the density and thermal insulation properties of porous materials on the alkali concentration in the silicon composition and the completeness of the reaction of the interaction of alkali with amorphous silica.

According to patent sources, the concentration of alkali in the compositions based on siliceous rocks is 8-30% [5]. A low bulk density of granular porous products - 80-120 kg / m ³ according to this method is obtained only with a maximum alkali concentration of 30%. It is known that siliceous rocks of different deposits are characterized by various properties, including the intensity of chemical interaction with alkali. The chemical activity of siliceous raw materials is determined by the concentration of chemically active amorphous silica in the rock. To obtain a light heat-insulating porous material from siliceous raw materials with low chemical activity, the maximum amount of alkali should be added to the compositions - 30%. However, alkali belongs to the second class of harmfulness and its high concentrations in the compositions create an unfavorable ecological environment for personnel, in addition, alkali is an expensive material, the cost of which is 30,000 rubles. per ton.

It is known that it is possible to increase the rate of pore formation of compositions with a minimum alkali concentration by introducing special blowing agents into the silicon composition. For example, there is a known method for producing porous building material [6] from natural siliceous raw materials with an alkaline component and with the addition of a special blowing agent, which is used as a mixture of sodium or potassium sulfate with sodium alkyl sulfate. From such compositions receive a light heat-insulating material. The disadvantage of this method is the complexity and inefficiency of the process in connection with obtaining a creamy siliceous-alkaline mixture with a gas-forming substance. This method is uneconomical due to the large heat loss for drying the mass with high humidity, and it is also impossible to form granules from such a mass and, therefore, it is impossible to produce granular heat-insulating materials. In addition, sodium alkyl sulfate is a non-common compound.

Known blowing agents (carbon or carbonate) used in the manufacture of foam glass from glass powder in compositions based on siliceous raw materials are ineffective. Carbon blowing agents burn out before a melt is formed in this composition, sealing them in micropores. Carbonate blowing agents are also not used in siliceous formulations for a number of reasons.

This circumstance has led to the fact that in the known compositions, methods and technological lines for the production of granular porous materials from siliceous raw materials, only alkali with a solution concentration above 45% is used as a melt and a substance forming a source of pore-forming gases. However, at this concentration of alkali, dissolved NaOH is prone to crystallization and precipitation.

In addition, the mixing of the powder of siliceous raw materials with a highly concentrated alkaline solution is accompanied by a violent reaction of the formation of liquid glass with heating of the mass to 80-90 ° C. The high temperature of the mass with a large amount of liquid glass formed leads to the stickiness and clumping of the hot mass, which complicates the granulation process.

In this regard, the use of highly concentrated alkaline solutions virtually eliminates the possibility of creating a continuous production line with an automated process for the preparation of alkali solution and its transportation in closed systems that create environmental safety in the workplace.

In addition, well-known production lines that do not involve the use of additional blowing agents in the compositions can produce granular porous material only from siliceous materials with a high content of chemically active amorphous silica, as the main component in the reaction of formation of a pore-forming gas source - liquid glass. This is a limitation in the use of known production lines, since not all deposits of siliceous rocks are characterized by a high content of chemically active amorphous silica.

The closest technical solution to the proposed model of the device is a technological line for the production of granular foam-ceramic material from siliceous rocks [2], which consists of three sections sequentially installed and interconnected by conveyors: preparation of raw materials, obtaining raw granules and heat treatment. The raw material preparation section includes a silicate raw material warehouse, a drying drum, a crusher and a first fractional separator. The raw granule production area includes a raw material storage bin, an alkaline component bin, a mixer, a dryer, a raw granule storage bin. The heat treatment section includes a heat treatment furnace, a dust fraction bin (separation medium), a second fractional separator, and a finished product warehouse.

In a known solution, an alkali solution with a concentration of 50% is used. Due to the high concentration, the preparation of such an alkali solution and transportation cannot be carried out in automated sealed devices. In addition, mixing a solution of an alkaline component with coarse-grained raw materials crushed in a crusher to a class of -5 mm will lead to an inhomogeneous distribution of alkali in the composition and, as a result, to low inhomogeneous pore formation. The increase in granules in volume after firing twice corresponds to a density of porous material of at least 600 kg / m ³ . This density is high for the insulating porous material. However, even such pore formation of granules on a known production line can be carried out using siliceous raw materials only with a high content of active amorphous silica.

The proposed utility model solves the technical problem of creating an integrated production line with enhanced functionality for the production of lightweight heat-insulating granular porous material from siliceous materials with different contents of chemically active amorphous silica while reducing production costs and improving the environment.

The stated technical problem is solved by the fact that in the integrated technological line for the production of granular porous material from siliceous raw materials containing structural elements that provide the preparation of raw materials, obtaining raw granules and heat treatment of the obtained granules, the structural elements are interconnected into a single continuously operating technological line with successively installed receiving hopper silica feed dispenser, crusher, fine grinding equipment and mechanoak raw material evacuation, a prepared raw material hopper, a granulator mixer, a dryer, a foaming oven, a classifier and a finished product warehouse, while a gasifier hopper and an alkaline component hopper are installed in parallel with the prepared raw materials hopper, the outputs of which are connected to the input mixer-granulator, and in parallel with the foaming furnace, a dosing hopper of a separation medium is installed, the output of which is connected to the input of the furnace, and the input is connected to the output of the classifier, and the foaming furnace with Placed with a device for exhaust gas, the output of which is connected to the inlet of the dryer.

The proposed complex technological line in the form of structural elements - equipment or units installed sequentially and in parallel and interconnected by conveyors or pipelines into a single device, is a continuously operating line that allows to achieve a technical result - to produce light heat-insulating granular porous material from siliceous raw materials of various deposits with different content of reactive amorphous silica while reducing production costs and increasing the environmental safety of the production process.

The proposed technical solution is illustrated by the installation block diagram.

The drawing shows a block diagram of an integrated production line for the production of granular porous material from siliceous raw materials.

An integrated production line consists of the following structural elements installed in series and parallel and interconnected by conveyors or pipelines (shown in lines): receiving silica feed hopper (1), crusher (2), equipment for fine grinding and mechanical activation of raw materials (3 ), a hopper-dispenser of prepared raw materials (4), a hopper-dispenser of a blowing agent (5), a hopper-dispenser of an alkaline component (6), a mixer-granulator (7), a dryer (8), a foaming furnace (9), an outlet device -governing gases (10), a classifier (11), the hopper separating media (12), a warehouse of finished products (13).

Using the proposed production line, it is possible to produce light porous granular building material from siliceous raw materials - tripoli, flask, diatomite and other similar rocks of various deposits with different contents of chemically active amorphous silica. The production line also allows the use of aluminosilicate rocks, for example zeolite-containing tuffs.

The difference in the content of chemically active amorphous silica in the siliceous raw materials of various deposits is compensated by the introduction of a blowing agent into the bunker-metering line. In the proposed integrated production line, carbonate materials such as calcite, chalk, dolomite, or mixtures thereof are used as blowing agents. Depending on the chemical activity of the siliceous feed and, consequently, the rate of pore formation of alkaline compositions, the concentration of the gas-forming component can vary in the range of 3-12%. Moreover, the maximum concentration of alkali in the compositions does not exceed 15%.

It is known that thermal decomposition of calcite (chalk) CaCO ₃ ↔CaO + CO ₂ ↑ is a reversible process and can only be carried out at a low partial pressure of the exhaust gases [7, 8]. Those. the decomposition of these carbonates with the release of the gas phase - CO ₂ can occur only when removing the exhaust gases from the reaction region. This feature has determined the need to remove the evolved gases from the foaming furnace, which is ensured by introducing into the installation line for exhaust gases and transporting them to a dryer for drying wet granules. This provides a reduction in energy costs for its drying.

In addition to introducing an additional blowing agent into the compositions, an increase in the rate of pore formation of granular material in the proposed integrated technological line is ensured by the installation of new generation high-performance equipment for fine grinding and mechanical activation of siliceous raw materials - a vortex mill-dryer ISU-20.55M or another similar to this one. Such a mill ensures the simultaneous occurrence of three processes: drying of raw materials, fine grinding (class -150 + 0 microns) and mechanical activation of crushed particles. High performance of the vortex mill-dryer is ensured by the fact that each particle of the siliceous raw material is dried in a vortex stream of hot coolant with its simultaneous fine grinding and mechanical activation.

The grinding proceeds in the fluidized bed due to the free blow of the rotor mill, which ensures high dispersion of the powder. The surface of the crushed particles after such grinding becomes highly reactive due to the formation of fragmentation-type particles with a high defective surface of the powder particles. Such mechanically activated powders are energy saturated with a high reactive particle surface. This activates both the low-temperature process of silicate formation with the formation of liquid glass with a minimum alkali concentration in the mass, and a decrease in the sintering temperature of the crushed particles of siliceous raw materials, which prevents premature complete decomposition of gas-forming carbonate compounds (calcite, chalk, dolomite).

Thus, the proposed device, an integrated technological line for the production of granular porous material from siliceous raw materials, allows expanding the raw material base through the use of siliceous rocks with different contents of chemically active amorphous silica while reducing production costs and increasing the environmental safety of production. This is ensured by the fact that in the proposed line as an additional blowing agent, inexpensive, affordable, environmentally friendly blowing agents, such as calcite, chalk, dolomite, or mixtures thereof can be used. The cost of production is reduced by reducing energy consumption, alkali concentration in the compositions and bulk density of the porous material. The environmental safety of production at the proposed integrated continuous production line is ensured by a control system for grinding processes, heat treatment, feeding, transportation, mixing and granulation of the charge components. Reducing the concentration of alkaline solutions below the crystallization threshold and precipitation allows the environmentally hazardous operations of preparation, transportation of alkali solution and granulation of the mixture in closed automated devices. This prevents dusting of powders and evaporation of alkaline solutions.

The heat-insulating granular porous material obtained on the proposed integrated production line from siliceous raw materials, depending on the properties of the raw materials used, is characterized by a bulk density of 90 to 300 kg / m ³ .

Distinctive features of the proposed model have a causal relationship, are aimed at achieving a technical result and are significant. The achievement of the technical result is provided by a single set of new essential features with the known.

A comprehensive technological line for the production of granular porous material from siliceous raw materials is as follows.

Siliceous raw materials (flask, tripoli, diatomite and other similar breeds) from the receiving hopper-dispenser (1) are fed into the crusher (2), which can be installed clay shredder or any other crusher that allows rough crushing of raw materials to class -20+ 0 mm The crushed raw materials are conveyed by a conveyor to a device for fine grinding and mechanical activation of raw materials (3), which is equipped with a high-performance vortex mill-dryer, which simultaneously performs three functions: drying the raw material to the required desired residual moisture, fine grinding it to class -150 + 0 μm and mechanical activation. Mechanically activated powder with a high reactivity is fed into the hopper-dispenser of the prepared raw materials (4), from which it is supplied in a metered amount to a mixer-granulator (7). Simultaneously with the raw material powder, a metered amount of gas-forming material is supplied to the mixer-granulator (7) from the hopper-dispenser of the blowing agent (5), carbonate compounds (calcite, chalk, dolomite or mixtures thereof) are used. The two components are mixed in a granulator-mixer (7) initially in a dry state for 1-2 minutes, after which a metered amount of an aqueous alkali solution with a concentration of 35-40 is supplied from the metering hopper of the alkaline component (6) to the granulator-mixer (7) % through a special sealed device that prevents the evaporation of alkali into the atmosphere. Mixing a dry mixture of powders with an alkali solution is carried out until the entire mass is homogenously moistened. The humidification of the powder in the mixer-granulator (7) is accompanied by the formation of a polydisperse granulate of class -10 + 0 mm. The moistened granulate enters the dryer (8), which can be installed drum dryer, in which the wet granules are dried with hot exhaust gases from the foaming furnace (9). Dry granules from the dryer (8) enter the foaming furnace (9), where the granules are melted and foamed at a temperature of 750-900 ° C. The foaming furnace (9) is equipped with a device (10) for discharging exhaust gases from the calcined material to the dryer (8) to use the heat of the exhaust hot gases to dry the wet granulate. Separating medium in the form of kaolin powder or other refractory powder, which dusts the raw granules, preventing them from sticking together during melting and foaming, enters the foaming furnace (9) from the metering hopper (12) together with the granules. After foaming, the granules together with the separation medium enter the classifier (11), where the separation medium (dusting powder) is separated from the granules. The separation medium is returned through the transport system back to the hopper-dispenser (12) for dusting the granular raw material entering the foaming furnace. Porous granules are scattered on the classifier (11) by fractions and fed to the finished goods warehouse (13).

The layout of the structural elements of the proposed device is an integrated technological line for the production of granular porous material from siliceous raw materials due to the composition of the raw material mixture selected for the production of granular porous material and the technological process of its manufacture.

The proposed integrated technological line for the production of granular porous material from siliceous raw materials has been mastered in industrial production and provides good quality environmentally friendly products - heat-insulating granular porous material.

The possibility of manufacturing a heat-insulating granular porous material from siliceous raw materials of various deposits, differing in the content of amorphous silica and, therefore, differing in the rate of pore formation of compositions based on them, is illustrated by the following examples on the proposed complex technological line.

Example 1

The flask of the Shipovskoye deposit (southern Urals) was taken as siliceous feedstock, the chemical composition of which is presented in Table 1.

The manufacture of porous granular products was carried out according to the above description of the production of porous material. The concentration of the components of the mixture on the dry part was, wt. %: flask - 80; chalk - 5; NaOH - 15. At a foaming temperature of 800 ° C obtained granular porous material fraction 4-6 mm with a bulk density of 90 kg / m ³ .

Example 2

Tripoli of the Potaninsky deposit (Urals), the chemical composition of which is presented in Table 2, was taken as siliceous feed.

The manufacture of porous granular products was carried out according to the above description of the production of porous material. The concentration of the components of the mixture on the dry part was, wt. %: tripoli - 76; chalk - 10; NaOH - 14. At a foaming temperature of 840 ° C obtained granular porous material of a fraction of 3-5 mm with a bulk density of 180 kg / m ³ .

Example 3

Tripoli of the Dabuzh deposit (Kaluga region), the chemical composition of which is presented in Table 3, was taken as siliceous feed.

The manufacture of porous granular products was carried out according to the above description of the production of porous material. The concentration of the components of the mixture on the dry part was, wt. %: tripoli - 83; chalk - 3; NaOH - 15. At a calcination temperature of 820 ° C, a granular porous material of a fraction of 5-7 mm with a bulk density of 240 kg / m ^{3 was} obtained.

Thus, the proposed integrated production line, which is a continuously operating line, allows to achieve a technical result - to produce lightweight insulating granular porous material from siliceous raw materials of various deposits with different contents of reactive amorphous silica while reducing production costs and increasing the environmental safety of the production process.

The proposed utility model of the technological line is not limited to the given examples, but is determined by the formula of the utility model taking into account possible equivalents.

List of sources used

[1] Kazantseva L.K., Storozhenko G.I., Nikitin A.I., Kiselev G.A. "Thermal insulation material based on flask raw materials." Construction Materials. No. 5, 2013, p. 85-89.

[2] RF patent for utility model No. 100073 "Technological line for the production of granular foam-ceramic material", Bubenkov OA, Ketov AA, Ketov PA, Lobastov SV, IPC C04B 38/00, publ. . 12/10/2010 (prototype).

[3] RF patent for utility model No. 115351 "Technological line for the production of granular foam silicate material", Ketov PA, Ketov Yu.A., Bubenkov OA, Lobastoe SV, IPC C04B 28/26, publ. . 04/27/2012.

[4] RF patent for utility model No. 62393 "Integrated production line for the production of granular porous material", Sheremet IM, Temnikov AV, Ledovskikh AV, Kurushov VA, Borisov GA, IPC C03C 11/00, C04B 14/00, publ. 04/10/2007.

[5] RF patent for the invention No. 2329986 "Method for producing granular insulating material", Fedyaeva LG, Aleshin SV, Matveev IO, Terekhin DA, IPC C04B 28/26, C04B 40 / 00, publ. 07/27/2008.

[6] RF patent No. 2363685 "Method for the production of building material", Dyukova E.Yu., Ivanov SV, Boriseev AV, Kuznetsov VA, IPC C04B 38/02, publ. 09/10/2009. [7] Mikhailenko Y.I. "The course of general and inorganic chemistry." - M.: Higher School, 1966.664 p. (see page 163).

[8] Velichko A.E. "Workshop on quantitative analysis." - M .: Rosvuz. Publ., 1963.112 p. (see page 33).

Claims (1)

A comprehensive production line for the production of granular porous material from siliceous raw materials, containing structural elements that provide the preparation of raw materials, obtaining raw granules and heat treatment of the obtained granules, characterized in that the structural elements are interconnected into a single continuously operating technological line with successively installed receiving silica feed hopper , crusher, equipment for fine grinding and mechanical activation of raw materials, hopper ohms of prepared raw materials, a granulator-mixer, dryer, a foaming oven, a classifier and a finished product warehouse, while in parallel with the prepared raw materials bunker, a gasifier bunker and alkaline component bunker are installed, the outputs of which are connected to the inlet of the granulator-mixer, and in parallel with the foaming furnace, a dosing hopper of a separation medium is installed, the output of which is connected to the inlet of the furnace, and the input is connected to the output of the classifier, and the foaming furnace is equipped with a device for removal flue gases, whose output is connected to the inlet of the dryer.

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