RU2482092C2 - Method of making light colour building ceramic - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to the industry of construction materials and can be used in making ceramic face brick from red-burning low-melting clay. According to the method, mineral additive is prepared by mixing and combined grinding of a lightening agent, sand and a fluxing agent. The lightening agent used is chalk and the fluxing agent used is calcined soda, while ensuring the following weight ratio of components in the mineral additive: chalk 40-55%; sand 40-57%; calcined soda 3-6%. The mineral additive is crushed to particle size of the lightening component of not more than 10 mcm. The mineral additive is mixed with clay while ensuring weight content of the mineral additive in the ceramic mixture of 16.5-24.3%. The articles are fired at temperature of 1010-1060°C.

EFFECT: simple process of making light colour brick from red-burning clay while maintaining high mechanical strength of the articles.

3 cl, 3 ex, 6 tbl, 1 dwg

Description

The invention relates to the building materials industry, and more particularly to methods for producing ceramic materials based on clay raw materials, and can be used for the manufacture of red-baked low-melting clay, mainly facial ceramic bricks, tiles, ceramic tiles of light colors.

The prior art ceramic mass for the production of bricks, in the preparation of which the components are dosed in the required quantities. Ground phosphogypsum and / or gypsum are mixed with silica sand, chalk, potash and / or soda ash. The mixture is fused at a temperature of 1350 ° C. The melt is granulated into water, then ground to a powder state. The resulting powder is mixed with fuel ash, clay and a ceramic mass is prepared with a moisture content of 18-23%. Brick is molded from the ceramic mass in a plastic way, which is dried to a moisture content of 1-3% and fired at a temperature of 900 ° C, see US Pat. RU, cl. С04В 33/135, No. 2393134, published July 26, 2010. Brick made from the indicated ceramic mass is characterized by increased mechanical strength. The disadvantage of the invention is the inability to manufacture using the described formulation of light brick.

A known method of manufacturing a facing brick by joint wet grinding of cullet and slag of electrothermophosphorus production, mixing with low-grade sandy clay and high-quality plastic clay, processing blanks and firing at a temperature of 980 ° C, characterized in that the components are mixed in the following ratio, in wt.%: cullet 20, slag of electrothermophosphorus production 15, low-grade sandy clay 32.5, high-quality plastic clay 32.5, and then the mixture is ground to fineness, the residue is si e 0.355 to 4%, and is dewatered in a spray drier to a moisture content of 4-8%, cm. Pat. RU, cl. С04В 33/02, No. 2070177, published on December 10, 1996. The method allows to exclude the drying operation, increase the physicomechanical properties of the brick, utilize a large amount of cullet and use it for the production of local clay. The disadvantage of these methods is the low degree of grinding of materials, as a result of which incompleteness of binding of the components and deterioration of the operational properties of the product are observed.

A known method of manufacturing building ceramics of light yellow color based on fusible red-burning clay, including the preparation of a mineral additive, mixing the additive with clay, plastic molding of products and firing, characterized in that the additive is prepared according to the slip method by grinding the brightening component of the additive together with 8-10 % clay from the mass of the clarifying component in a ball mill to the residue on a 0088 sieve of no more than 2-3%, followed by the introduction of a hardening finely dispersed component into the suspension additives, then the resulting slurry density of 1,70-1,72 g / cm ³ is mixed with the clay, of which the pre-dried to a moisture content of 6-8%, the resulting ceramic body is homogenized and be aged for at least 24 hours, and calcination is conducted at a temperature 1020-1030 ° C, while marl with a particle size of less than 2 mm with a limestone content of at least 75 wt.% Is used as a brightening component, and wollastonite concentrate with a particle size of less than 0.063 mm with a wollastonite content of at least 80 wt. %, with their content in the ceramic mass (wt.%): fusible clay 50-60, marl 30-35, wollastonite concentrate 10-15, see US Pat. RU, cl. СВВ 33/02, No. 2266878, published December 27, 2005. The method is characterized by improved mechanical strength, frost resistance and decorative properties of the resulting brick. This well-known technical solution was adopted as a prototype as the closest analogue in technical essence and achieved result.

The disadvantage of the prototype is the need to dry part of the clay raw material to a residual moisture content of 6-8%, which is a source of increased dust content of brick production, as well as the need to use a less common component - wollastonite concentrate, which in the invention plays the role of a strengthening component of ceramic brick during its firing. These disadvantages of the prototype significantly complicate the process and sanitary conditions for the manufacture of face bricks in bright colors from red-burning clay, which results in a high cost of finished products.

The present invention is aimed at achieving a technical result, which is expressed in the simplification of the technological process and in providing the possibility of producing face bricks of light colors from red-burning clays in almost any brick factory. Ultimately, the specified technical result allows to improve the quality of finished products, reduce the consumption of fuel and energy resources and the cost of finished products, improve sanitary and hygienic conditions of production. In the developed method for the manufacture of light-colored building ceramics based on red-burning clays, all the positive properties of the prototype are maximally preserved, the most important of which is the improvement of the mechanical strength of ceramics.

The specified technical result is achieved in that the method of manufacturing light-colored building ceramics based on red-burning clays, including preparing a mineral additive, mixing the additive with clay, molding products and firing, differs from the prototype in that the mineral additive is prepared by mixing and co-grinding the clarifying component , sand and flux, while chalk is used as a clarifying component, and soda ash is used as flux, ensuring the ratio the mass fraction of the components in mineral supplements:

chalk 40-55%

sand 40-57%

soda ash 3-6%,

grinding the mineral additive is carried out to a particle size of the clarifying component of not more than 10 μm, and mixing the mineral additive with clay is carried out to ensure the content of the mass fraction of the mineral additive in the ceramic mass is 16.5-24.3%, the products are fired at a temperature of 1010-1060 ° C .

According to the method, mainly, the preparation of the mineral additive is carried out by mixing and co-grinding the clarifying component, sand and fluff in a core mixer. Optimal from the point of view of achieving the specified technical result is the firing of products in furnaces of periodic or continuous action.

The technical solution, characterized by the described combination of essential features, is new, industrially applicable and has an inventive step.

The essence of the technology of volumetric staining of the ceramic mass due to the introduction of chalk is to finely grind the clarifying additive in the core mixer in a dry way to the minimum possible and thorough mixing of the components.

The developed method for producing light-colored building ceramics is based on a unique technology for preparing a mineral additive, carried out by mixing and co-grinding the clarifying component (chalk), sand and flux, where each component in a given ratio performs a certain function. At the same time, chalk should meet the requirements of GOST 174498, and sand - the requirements of GOST 8736 with a particle size module of 1.5-2.5. Specifically, sand acts as a grinding material for dispersing and grinding chalk, as well as a compacting component in the raw material mixture, which makes it possible to increase the density of the calcined products, and therefore, significantly reduce the water absorption of the calcined ceramic shard. Melting (soda ash, Na ₂ CO ₃ ) reduces the firing temperature of ceramic products by 50-80 ° C. As a result of thorough mixing and grinding of chalk, sand and melt in a rod mixer, grinding of the clarifying component is achieved to a particle size not exceeding 10 microns, which is practically unattainable on standard equipment of a different type.

The experimentally established limit values for the ratio of the mass fraction of components in the mineral additive and the mass fraction of the mineral additive itself in the ceramic mass are optimal and sufficient to obtain the necessary characteristics of building ceramics, including their color saturation and strength.

Thus, all the features that are distinguishing from the prototype of the method for producing light-colored face bricks from red-burning clays, both general and private, are aimed at obtaining a technical result, namely, simplifying the process, improving the quality of finished products, reducing the consumption of fuel and energy resources and the cost of finished products Improving the sanitary and hygienic conditions of production.

The technical solution is illustrated by the diagram.

The figure shows an exemplary flow chart of the production of light-colored facial ceramic bricks from red-burning clays by the plastic method of molding raw material.

In accordance with the presented technological scheme, the production of ceramic thermal insulation and structural material is as follows.

The initial components for the preparation of a mineral additive, namely chalk 40-55%, sand 40-57% and soda ash 3-6%, dispensed by screw or belt feeders in the required proportions, are fed for preliminary mixing into a batch or continuous mixer. When mixing chalk, sand and soda ash, the moisture content of the chalk is predominantly 1-10%, the moisture content of sand is 4-7%, and the moisture content of soda is 1-10%. From a pre-mixing mixer (a continuous screw mixer is shown in the diagram), a mixture of three components is fed to a continuous rod mixer, in which the components of the mineral additive are thoroughly mixed and the particles of chalk are dispersed to a fineness of no more than 10 microns. At the indicated humidities of the components, dusting is not observed when processing in a core mix, and the mixer itself, which is a rotating container with metal rods freely moving in it, works stably. Description of the technology for obtaining the specified degree of grinding, the corresponding equipment, technological modes, as well as methods for controlling the finished mixture in composition, humidity, degree of grinding, etc. described in detail in the book “Ceramic wall materials: optimization of their physical and technical properties and technological parameters of production”. V.A. Kondratenko. Moscow, Composite, 2005, p. 120, 356-357). The mineral additive thus ground is fed into a twin-shaft clay mixer, where it is mixed with red-burning clay that has undergone preliminary processing on clay processing equipment, ensuring the content of the mass fraction of the mineral additive in the ceramic mass is 16.5-36.5%, the rest is clay. The mixed raw mix is processed according to the scheme adopted at a particular brick factory on clay processing machines. Raw material is formed from the processed charge in a plastic or semi-dry way. The raw material is dried in dryers and fired in batch or continuous furnaces at a temperature of 1010-1060 ° C.

The possibility of implementing a method of manufacturing building ceramics in light colors based on red-burning clays is confirmed by the following examples.

Example 1

The clay component was taken from the clay of the Offshore field of the Yaroslavl region, the chemical composition of which is presented in Table 1.

The dosed components of the mineral additive were mixed in a mixer and processed in a core mixer to a fineness of chalk less than 10 microns. The milled mineral additive was mixed with clay of career moisture 19-22%. The raw material charge was processed on clay processing equipment and molded beam samples with dimensions of 140 × 40 × 25 mm and cubes with dimensions of 50x50x50 mm. The samples were dried to a residual moisture content of 2-2.5% and calcined in a laboratory furnace according to the following regime: temperature rise in the furnace to 900 ° C for 8 hours, temperature rise from 900 to 1020-1060 ° C for 4 hours, isothermal exposure at maximum temperature - 2 hours. Cooling from maximum temperature to 50 ° C - 10-12 hours. After cooling, the samples were removed from the furnace and the physicotechnical properties of the calcined samples were studied. The compositions of the mineral additives and raw materials, as well as firing parameters and physico-technical properties of the calcined samples are shown in table 2.

All samples withstood 50 cycles of alternate freezing and thawing.

Example 2

As the clay component, clay of the Nikolskoye deposit of the Leningrad region was taken, the chemical composition of which is presented in table 3.

The dosed components of the mineral additive were mixed in a mixer and processed in a core mixer to a fineness of chalk less than 10 microns. The milled mineral additive was mixed with clay with a career moisture of 18-21%. The raw material charge was processed on clay processing equipment and molded beam samples with dimensions of 140 × 40 × 25 mm and cubes with dimensions of 50 × 50 × 50 mm. The samples were dried to a residual moisture content of 2-2.5% and calcined in a laboratory furnace according to the following regime: temperature rise in the furnace to 900 ° C for 8 hours, temperature rise from 900 to 1010-1030 ° C for 4 hours, isothermal exposure at maximum temperature - 2 hours. Cooling from maximum temperature to 50 ° C - 10-12 hours. After cooling, the samples were removed from the furnace and the physicotechnical properties of the calcined samples were studied. The compositions of the mineral additives and raw materials, as well as firing parameters and physico-technical properties of the fired samples are shown in table 4.

All samples withstood 75 cycles of alternate freezing and thawing.

Example 3

As the clay component, clay of the Sebrovsky deposit of the Volgograd region, the chemical composition of which is presented in table 5, was taken.

The dosed components of the mineral additive were mixed in a mixer and processed in a core mixer to a fineness of chalk less than 10 microns. The milled mineral additive was mixed with clay with a career moisture of 21%. The raw material charge was processed on stone extraction rollers, then in a screw press with a filter grate. The granules were dried to a residual moisture content of 7%. The dried granules were processed in a core mixer to bring the molding moisture of the press powder to 7.5%. Samples of cylinders with a diameter of 50 mm, a height of 52 mm and a specific pressing pressure of 200 kgf / cm ^{2 were} formed from the press powder by the method of semi-dry pressing. The samples were dried to a residual moisture content of 3-3.5% and fired in a laboratory furnace according to the following regime: temperature rise in the furnace to 900 ° C for 8 hours, temperature rise from 900 to 1020-1050 ° C for 4 hours, isothermal exposure at maximum temperature - 2 hours. Cooling from maximum temperature to 50 ° C - 10 hours. After cooling, the samples were removed from the furnace and the physicotechnical properties of the calcined samples were studied. The compositions of the mineral additive and raw materials, as well as firing parameters and physico-technical properties of the fired samples are shown in table 6.

All samples withstood 50 cycles of alternate freezing and thawing.

The examples of the method described above clearly confirm the possibility of implementing the method within the boundary values of the mass fraction of components and technological modes. However, the above examples are not exhaustive and are presented only for the purpose of explaining the invention and confirming its industrial applicability. Specialists in this field can improve it and / or implement alternative options within the essence of the present invention, reflected in the description and diagram.

An advantage of the invention is the possibility of manufacturing using the described method in virtually any brick factory from available raw materials of facial ceramic products in light colors from red-burning clay, providing high compressive strength, as well as low cost, with good sanitary and hygienic conditions of production.

Claims (3)

1. A method of manufacturing building ceramics of light colors based on red-burning clays, comprising preparing a mineral additive, mixing the additive with clay, molding the products and firing, characterized in that the preparation of the mineral additive is carried out by mixing and co-grinding the clarifying component, sand and flux, chalk is used as a clarifying component, and soda ash is used as flux, ensuring the ratio of the mass fraction of components in the mineral additive,%:
a piece of chalk 40-55 sand 40-57 soda ash 3-6,
grinding the mineral additive is carried out to a particle size of the clarifying component of not more than 10 μm, mixing the mineral additive with clay is carried out to ensure the content of the mass fraction of the mineral additive in the ceramic mass is 16.5-24.3%, the products are fired at a temperature of 1010-1060 ° C. 2. The method according to claim 1, characterized in that the preparation of the mineral additive is carried out by mixing and co-grinding the clarifying component, sand and fluff in a core mixer. 3. The method according to claim 2, characterized in that the firing of products is carried out in furnaces of periodic or continuous action.

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