RU2379258C1 - Method of manufacturing structural, heat insulating ceramics and composition for manufacturing thereof - Google Patents

Abstract

FIELD: building.

SUBSTANCE: method involves preparation of a bulk that is a mineral binding additive - zeolite rock, implying drying thereof at temperature 110-150°C and crushing to the size 0.5 mm and less, slip-process preparation of a fluidising agent by the combined wet ground of said zeolite rock to sieve residue 0088 no more than 2-3% in a ball grinder with adding calcium lignosulphonate (sulphite waste liquor) to produce zeolite-lignosulphonate slurry of density 1.20-1.25 g/cm³, plasticisation of cindery microspheres with the prepared slurry, mixing of a dry binding additive with plasticised microspheres, dry pressing of the products under pressure 20-25 MPa and baking of the half-finished product at temperature 980±20°C. The composition for manufacturing the ceramic material contains the components in the ratio, wt %: cindery microspheres 60-95, zeolite rock 5-40 wt %, zeolite-lignosulphonate slurry 12-16 over 100 %.

EFFECT: lower heat conductivity of pottery with maintaining high durability thereof.

2 cl, 3 tbl

Description

The invention relates to the production of structurally heat-insulating ash-containing ceramic materials and can be used in the manufacture of building wall ceramics with enhanced heat-insulating properties (ceramic bricks and ceramic blocks).

A known method of manufacturing ceramic products and the composition of the masses for the production of ceramic bricks, including the preparation of the clay part of the "tails" of gravity of zircon-ilmenite ores (20-30 wt.%), Mixing with ash TPP (70-80%), molding the semi-finished product in a plastic way, drying and firing at a temperature of 1050 ° С / Abdrakhimov D.V., Abdrahimova E.S., Abdrakhimov V.Z. Ceramic brick from industrial waste. - Building materials, No. 9, 1999. - S.34-35 /. The disadvantage of the resulting products is their high density (1380-1700 kg / m ³ ), which determines reduced thermal insulation properties.

A known method of obtaining and compositions of raw mixtures for thermal insulation of furnace units and power equipment, consisting in dosing refractory clay (2-50 wt.%) And light fraction of fly ash TPP (50-98 wt.%), Mixing the components and moistening with water in forced action mixer, semi-dry pressing of raw material, drying and firing of a semi-finished product / RF Patent for invention No. 2057742. Raw mix for the manufacture of ceramic-gold-insulating products. Shatalov V.I., Bernatsky A.F., Mikheev V.P., Rogacheva S.V. Stated August 28, 1992, publ. 04/10/1996 /. Products from this raw material mixture have low values of thermal conductivity (0.17-0.24 W / m · K). The disadvantage is the high values of water absorption of products, which limits the use of the proposed compounds in the technology of building ceramics.

A known method of manufacturing wall heat-insulating ceramic products, which consists in grinding dry clay raw materials, the introduction of hydrophobized grains of foam glass with a grain size of 0.1-5.0 mm, wetting the molding mixture to a moisture content of 10%, molding raw material by semi-dry pressing under a pressure of 4 MPa, drying and firing at a temperature of 900-950 ° C / RF Patent for the invention No. 2266267. Besedin P.V., Ivleva I.A., Mospan A.V. A method of manufacturing wall ceramic materials. Declared December 8, 2004, published December 20, 2005 /. The disadvantages of the method are the increased density of the obtained wall ceramic materials and, as a consequence, their high thermal conductivity.

A known method of manufacturing and the composition of the raw material mixture for thermal insulation products, including grinding clay raw materials to a size of less than 1 mm, mixing clay with a grain of foam glass in a screw mixer, followed by moistening with a 5% aqueous solution of sulphite-yeast mash, pressing products in a semi-dry way under pressure 10 MPa, drying the raw material to a residual moisture content of 2% and firing the semi-finished product at a temperature of 950 ° C / RF Patent for invention No. 2231505. Besedin P.V., Ivleva I.A., Mospan A.V. Ceramic mass for the manufacture of wall and facing products. Declared July 18, 2003, published June 27, 2004 /. As in the previous case, the disadvantages are the increased density and thermal conductivity of the obtained ceramic materials.

Closest to the proposed method is the manufacture and composition of the raw material mixture for ceramic-ceramic insulating products, which consists in dosing clay (20-30 wt.%) And ash microspheres (60-70%), mixing in a dry state in a mixer, moistening with water to a moisture content of the mass 25-30%, adding liquid glass with a density of 1.5 g / cm ³ to the mixture, molding samples at a pressure of 0.5-4.2 MPa, drying at a temperature of 60-80 ° C to a moisture content of 8-12% and firing the semi-finished product at temperature 800-950 ° С / Skripnikova N.K., Volokitin G.G., Shlykov D.V., Schmidt V.G., Petrochenko V. . Raw mix for the manufacture of building products. RF patent for invention No. 2200138. Declared 10/26/1998. Published on September 20, 2000 /. The resulting products have a low density (550-650 kg / m ³ ), which is ensured by the structure of ash microspheres, which are a hollow particle filled with gases. A significant drawback is the low strength value of finished products - 7.5-10 MPa, which does not allow their use as structural building materials.

The objective of the invention is to reduce the thermal conductivity of the ceramic structure by increasing its porosity while providing high strength products to obtain wall highly effective structural and heat-insulating ceramic materials.

The invention consists in regulating the structure of the pore space of the ceramic matrix through the use of a non-plastic technogenic component with its own highly porous structure (ash microspheres), a mineral binder additive (zeolite rock - a natural pseudoplastic component with an intracrystalline porous structure of the main rock-forming mineral) and a plasticizing additive (zeolite lignosulfonate slip) which is ensured by a set of operations, including the preparation of plasticizing the additive according to the slip method by co-wet milling the zeolite rock with calcium lignosulfonate (sulphite-alcohol stillage) in a ball mill to a residue on sieve 0088 of not more than 2-3%, plasticizing the ash microspheres by mixing with the obtained zeolite lignosulfonate slip with a density of 1.20-1, 25 g / cm ³ followed by the introduction of a dry mineral binder additive in the form of zeolite rock, dried at a temperature of 110-150 ° C and crushed to particle sizes less than 0.5 mm, molding products from the resulting raw material mixture with a semi-dry press by pressing under pressure of 20–25 MPa and firing the semi-finished product at a temperature of 980 ± 20 ° С.

The proposed composition for the manufacture of structural heat-insulating building ceramics is as follows (wt.%): Ash microspheres - 60-95, zeolite rock 5-40, zeolite-lignosulfonate slip - 12-16 (over 100).

The imaging effect of the ash microspheres in ceramic compositions is due to their hollow structure.

A decrease in the content of ash microspheres in the composition of the ceramic mass of less than 60 wt.% Leads to an increase in the density and thermal conductivity of the products.

As a mineral binder component, a pseudoplastic rock is used, consisting mainly of minerals with developed skeleton-cavity porosity - zeolite rock, in an amount of 5 to 40 wt.% With a zeolite mineral content of at least 60%.

The choice of zeolite-containing rocks as a binder mineral additive is due to its certain plasticity and binder ability in a crushed state, and at the same time to have its own structural porosity, which is determined by the structural features of zeolite minerals composing such rocks, since zeolites are aqueous alkali and alkaline-earth aluminosilicates metals with a developed porous structure. The crystalline three-dimensional framework of zeolites is penetrated in several directions by large cavities (pores, channels) connected to each other and to the surface of the crystal. The total volume of pores and channels can reach 50% of the volume of the mineral. The intracrystalline cavities and channels are filled with so-called zeolite water, which, having weak hydrogen bonds with the framework, is easily released from the crystals upon slow heating in the temperature range 110-400 ° C without violating the structure of the framework.

Grinding a technological additive to a particle size of less than 0.5 mm is necessary to increase the ductility and cohesion of the zeolite rock, as well as to create a homogeneous fine-grained ceramic mixture.

Grinding zeolite rock to a particle size greater than 0.5 mm leads to a deterioration in the molding properties of zeolite-containing masses.

The creation of a highly porous structure of ceramic products made semi-dry from traditional ash-containing masses is possible provided the prevailing content of ash microspheres in compositions with natural binder raw materials, in which the ash-containing material acts as the main structure-forming component. This determines the need to find ways of additional plasticization of such masses to create a strong contact between the binder and the base particles, since in the case of dry mixing of the natural binder with microspheres, subsequent wetting of the mixture to a state of semi-dry masses (with a moisture content of 6-8%) does not fully reveal the binder's binding ability and, as a result, obtaining tightly bound masses, which negatively affects the mechanical properties of the raw material and, ultimately, the finished product.

The natural binder component is poorly bound to the vitrified surface of the ash microsphere. Plasticization of cindery microspheres, the essence of which is to modify the state of the glassy surface of the microspheres during their pretreatment with a plasticizing additive in the form of a zeolite-lignosulfonate slip in an amount of 16-18% (over 100), followed by mixing with a binder zeolite rock, provides close contact between moistened non-plastic particles of cindery microspheres with a bundle, the finely dispersed part of which adheres to the surface of the microsphere due to the action of tarry and sugar substances sulfite-alcohol stillage and held firmly on it. The resulting layers between the ash microspheres contribute to a decrease in shear forces during the pressing of articles.

The composition of the zeolite-lignosulfonate slip (wt.%): Zeolite rock - 40, calcium lignosulfonate (sulphite-alcohol stillage) - 10, water - the rest.

The choice of press pressure of 20-25 MPa when molding products in a semi-dry way is due to the need to ensure high strength characteristics of raw, dried semi-finished and finished products.

The use of pressing pressure below 20 MPa does not provide the strength of the semi-finished product, sufficient for further transport operations in a real process. Increasing the pressing pressure in excess of 25 MPa is impractical due to an excessive increase in the density of the finished product.

Example

As a structure-forming component according to the claimed method, ash microspheres of the Belovskaya state district power station (Kemerovo region) are used.

Ash microspheres are a light fraction (bulk density of 300-400 kg / m ³ ) ash from the combustion of solid fuels. In the case of ash removal by the wet method, due to the low density, the microspheres form a floating layer on the water surface of the sump, which is easily collected and removed.

Ash microspheres are composed of regular hollow spherical formations with a smooth shiny surface with a diameter of 50 to 250 microns, with a wall thickness of 2-5 microns. The melting point of the microspheres is 1200-1300 ° C, which allows them to be attributed to low-melting ash-containing raw materials. The phase composition of the ash microspheres is represented by the glass phase in an amount of 90%; quartz is fixed in the crystalline part.

Zeolite rock of the Sakhaptinsky deposit (Krasnoyarsk Territory) is used as a mineral binder. In appearance, the breed is loose with grains of irregular angular shape of light brown color, fraction 6 ± 1 mm. The raw material is characterized as clinoptilolized tuffs of a polymineral zeolite composition, represented by a mixture of clinoptilolite, heylandite and mordenite with a predominance of clinoptilolite.

The characteristics of the raw materials in chemical composition are given in table 1.

Preparation of a mineral binder additive (zeolite rock) includes drying the additive in a drying drum at a temperature of 110-150 ° C and fine grinding to a size of less than 0.5 mm.

The preparation of the plasticizing additive is carried out by the slip method by co-wet (water - 50 wt.%) Grinding in a ball mill to a residue on a 0088 sieve of not more than 2-3% zeolite rock (40 wt.%) With the addition of calcium lignosulfonate (sulphite-alcohol stillage) - 10 wt.%).

Dosage of all components is carried out in a weighted manner. Component compositions of ceramic masses are given in table.2.

Plasticization of the ash component is carried out by treating it with a prepared zeolite-lignosulfonate slip with a density of 1.20-1.25 g / cm ³ in the amount necessary to obtain a ceramic mass with a moisture content of 6-8%.

The preparation of the ceramic mass consists in mixing the prepared binder with a plasticized ash component in light runners or a twin-shaft mixer.

Molding is carried out by semi-dry pressing under a pressure of 20-25 MPa.

It has been revealed that the use of zeolite rock in compositions with cindery microspheres, even with a marginal degree of depletion of 90-95%, provided that they are plasticized with a lignosulfonate zeolite slurry, makes it possible to obtain a semi-finished product with clear faces and with increased compressive strength (1.7-2.2 MPa) . In addition, the sufficient strength of the raw material and the low air shrinkage of the semi-finished product with ash microspheres (close to zero values) make it possible to eliminate the need for drying operations of the compacts in the process and ensure the stability of the size and shape of the finished products.

Semi-finished product is fired at a temperature of 980 ± 20 ° C for 16-20 hours with exposure at a final temperature of at least 2 hours. Lowering the firing temperature to less than 980 ± 20 ° C does not ensure the completeness of the sintering process and the formation of a strong structure of the porous ceramic product. Firing at temperatures above 980 ± 20 ° C is impractical due to the excessive increase in the density of products and the deterioration of their thermal insulation properties.

The properties of the calcined products are given in table.3.

Thus, the use of zeolite rock as a binder component in the composition of the ceramic mass in a composition with ash microspheres moistened with a zeolite lignosulfonate slip allows one to obtain semi-dry technology from compositions with ash microspheres from 60 to 95 wt.% At a firing temperature of 980 ± 20 ° С durable and highly effective structural and heat-insulating ceramic brick with a density of 930-1100 kg / m ³ with a thermal conductivity of 0.29-0.36 W / m · K and with a minimum guaranteed grade of at least M100-M125.

The creation of highly porous ceramic structures in compositions of fly ash microspheres with zeolite rock is caused both by the structural porosity of the rock-forming mineral of the zeolite rock, and by the structural features of the ash component (the presence of hollow spherical particles), and also hindering shrinkage during sintering by physicochemical processes in the zeolite rock - fly ash system microspheres ”(processes of synthesis of anorthite and mullite, occurring with an increase in molar volume).

Ensuring high strength of firing products from compositions of zeolite rock and ash microspheres moistened with a zeolite slurry with the addition of calcium lignosulfonate is due to the use of increased compression pressure of products (20-25 MPa), which leads to partial destruction of microspheres and the formation of sharp-fragment fragments reinforcing the binder component, so and improvement of specimen sintering due to: a) uniform distribution of a portion of the binder component in a slip-like state over the entire volume of ash microspheres p, c) adhesion adhesion of the main part of the binder in a dry state to the moistened and modified surface of the microsphere in the form of the thinnest films at the molding stage, b) baking of the ligament to the surface of the microsphere as a result of the creation of fusible eutectics in the films due to the introduction of an alkaline-earth component with a lignosulfonate solution calcium. All this together ensures the development of a glass-crystalline transition layer between the microsphere and zeolite binder and, as a result, an increase in the strength properties of products, since the thinner the layer between the elements of the ceramic structure, the higher the specific strength of the ceramic material.

Table 1
The chemical composition of raw materials Components The content of oxides,% SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ MgO Cao R ₂ O Δm _PPH. ash microspheres of Belovskaya state district power station 65.66 20.91 4.37 2.25 4.06 1.23 1,52 zeolite rock of the Sakhaptinskoye deposit (Krasnoyarsk Territory) 67.56 11.75 1.98 0.70 3.90 3.57 10.56

Table 3
Product Properties Property metrics Prototype Compositions one 2 3 four Outlawing compositions
BUT firing temperature, ° С 850-900 980 ± 20 980 ± 20 980 ± 20 980 ± 20 980 ± 20 density, ρ · 10 ^-3 , kg / m ³ 0.55-0.65 1,07 1.09 0.98 0.93 1.17-1.21 thermal conductivity, W / m · K 0.36 0.36 0.33 0.29 0.44 ultimate compressive strength
σ _squ , MPa 7.5-10 22.2 19.6 18.6 18.2 32,2 expected brick brand - M125 M100 M100 M100 M175

Claims (2)

1. A method of manufacturing structural and heat-insulating building ceramics, including the preparation of a mineral binder additive, moistening and plasticizing the ash component, mixing the binder additive with a plasticized ash component, semi-dry pressing of products and firing, characterized in that the plasticizing additive is prepared according to the slip method by joint wet grinding of the zeolite rocks with calcium lignosulfonate (sulphite-alcohol stillage) in a ball mill to a residue on sieve 0088 no more than 2-3%, carry out pl astification by mixing ash microspheres with the obtained zeolite-lignosulfonate slip with a density of 1.20-1.25 g / cm ³ , followed by the introduction of a dry mineral binder additive in the form of a zeolite rock, dried at a temperature of 110-150 ° C and crushed to particle sizes less than 0.5 mm, the molding of products from the obtained raw material mixture is carried out by semi-dry pressing under a pressure of 20-25 MPa, and firing is carried out at a temperature of 980 ± 20 ° C. 2. Composition for the manufacture of structural heat-insulating building ceramics containing ash microspheres, a binder mineral additive and a moisturizing plasticizing additive, characterized in that zeolite rock is used as a binder mineral additive, a zeolite-lignosulfonate slip is used as a moisturizing plasticizing additive in the following ratio of components, wt .%:
ash microspheres 60-95 zeolite rock 5-40 zeolite lignosulfonate slip 12-16 (over 100)