Method of manufacturing corundum refractory products

FIELD: refractory materials.

SUBSTANCE: invention relates to manufacture of corundum refractory articles based on mullite-corundum binder and used in linings of heat assemblies employed in variant industry fields. Method of invention comprises preparation of blend by way of moistening grainy corundum constituent with suspension of activating mullite-forming additive in industrial-grade lignosulfonate aqueous solution followed by mixing with finely ground corundum constituent, formation of articles from thus prepared blend, drying thereof, and firing at 1200-1500°C. Activating mullite-forming additive is finely ground silica/alumina mixture in eutectic weight ratio 94.5/5.5, respectively, used in amount 2-4% of the weight of total content of corundum constituents.

EFFECT: reduced power consumption on production of corundum refractory products due to lowered (by 200-500°C) firing temperature and reduced refuse.

1 tbl

 

The invention relates to refractory industry, namely the method of manufacture of corundum refractory bricks at mullitokorundovye conjunction used in thermal units, used in various industries.

A known method of manufacture of corundum refractories comprising preparing a mixture by mixing granular corundum with it component containing corundum and activating meritokratie supplements, moistening the mixture with an aqueous solution of lignosulfonate technical, extrusion products from the resulting mixture, drying and firing at a temperature of 1750°C. at the same time as activating militaermusik additives mixture contains distanceremaining concentrate and quartz sand in number, in which the ratio of SiO2: Al2About3in it is part of the mixture is 1:1,67-of 2.26 (IBV and other Production of dense heat-resistant corundum refractory to induction channel furnaces // Refractories, 1974, No. 10, s-17).

Obtained in a known manner corundum products are characterized by a tensile strength at compression 79-130 N/mm2open porosity of 9.5 to 13.3%, heat resistance mode 1300°With water 15 thermal cycles, the temperature of the beginning of the deformation under load of 0.2 N/mm21750°C.

Products have a structure in Kotor is the first large grains of corundum surrounded by a hyaline sheath, and a connecting part presents two phases - corundum and mullite.

The disadvantage of this method are significant energy consumption for its implementation, associated with the high firing temperatures of 1750°C. in Addition, due to the equality of the firing temperature and the temperature of the beginning of deformation products under load inevitable marriage of firing deformations and cracks.

Closest to the invention is a method of manufacturing corundum refractory products comprising preparing a mixture by wetting granular corundum suspension component activating multicourse additives (clay) in an aqueous solution of lignosulfonate technical and subsequent mixing with other components of the charge, including it corundum component, molding, drying and firing. To hydrate grains of corundum in a known way using 7-9 wt.% the suspension, which contains 2-4 wt.% the clay. As it is a component used isometric single-crystals of aluminum oxide size of 1-10 μm, which are sequentially mixed with the remainder of the clay in the number 1-13 wt.% and an aqueous solution of triethanolamine and methyl cellulose (USSR Author's certificate No. 1133247, IPC 04 In 35/10, publ. 07.09.84).

The product, obtained in a known manner, have an open porosity of 13-17%, Pres who ate the Flexural 49,9-58,4 N/mm 2the temperature at which deformation under load 1720-1740°C.

In the known method as the activating multicourse supplements use clay, the total amount of which in the mixture is from 3 to 17 wt.%. As you know, the clay contains a large number of low-melting impurities that adversely affect the quality of refractory products, in particular, reduces the temperature at which deformation under load.

Two-stage introduction of clay in the mixture in a known way creates the conditions for the formation of mullite as near grain boundaries and in the junction part of the refractories. However, the primary crystallization of mullite occurs in the presence of a large number of the liquid phase caused by impurities, which separates the grains of corundum and mullite, not allowing you to fully form crystalline aggregates, reinforcing the structure. To increase the degree of sintering and achieve higher strength corundum refractories in the known method it is necessary to carry out the roasting of products at temperatures below 1700°C.

High-temperature firing corundum products requires large energy consumption for the operation of the process, and is the cause of defective products resulting from deformation and cracking during firing due to the small difference between the temperature of the beginning of the fact deformation of the AI under load and temperature of firing.

The invention solves the problem of reducing energy consumption for the production of corundum refractory products by reducing the firing temperature, while maintaining the required level of properties of the products.

The technical result that can be obtained from the use of the invention is to achieve high strength refractory corundum products at a lower firing temperature, the temperature of the beginning of deformation products under load, as well as the waste reduction firing.

This technical result is achieved in that in the method of manufacture of corundum refractory products comprising preparing a mixture by wetting granular corundum suspension component activating multicourse additives in an aqueous solution of lignosulfonate technical and subsequent mixing with it corundum component, molding the resulting mixture, drying and firing, according to the invention in the preparation of the charge as the activating multicourse additives used it is a mixture of oxides of silicon and aluminum in the eutectic ratio, wt.%: 94,5 SiO2and 5.5 Al2About3in the quantity of 2-4 wt.% from the overall content of corundum components, and the roasting of products is carried out at a temperature of 1200-1500°C.

The use of activating the mule is itabritwoxeri supplements it is a mixture of oxides of silicon and aluminum in the eutectic ratio at the specified introduction it directly on grain corundum helps to increase the degree and rate of flow physico-chemical processes during the formation of the structure of corundum refractories, which reduce the firing temperature corundum products.

Low-temperature eutectic containing 94,5 SiO2and 5.5 Al2O3has a melting point of 1540°C. it is Known that in multi-component systems, the temperature of the occurrence of eutectic melt is significantly reduced. In this regard, at a temperature of about 1200°With the contacts grains of corundum is the crystallization of secondary mullite. As the number of the liquid phase is small, the crystals of mullite form a direct connection with the grains of corundum, thus forming a solid crystalline skeleton corundum products. Depending on the number of eutectic mixture of the hardening process increases up to a temperature of 1500°C.

The choice of the scope of content of the mixture of eutectic composition are due to the following. Reducing the amount of the mixture is less than 2 wt.% of the total number corundum components leads to the formation of an insufficient number of direct links in the structure of refractories and as a consequence, lower strength products. An excess amount of a mixture of more than 4 wt.% entails increasing the number of secondary mullite and a liquid phase, the excess of which leads to the loosening of the structure and reduction of the direct links that also have sativae is camping on the strength of products.

Conducting calcination at temperatures above 1500°not economically feasible. Reducing the firing temperature of less than 1200°does not provide the necessary degree of sintering, as evidenced by insufficient strength of the products.

Conducting firing corundum refractory products at the temperatures at 200-500°With lower than in the known methods, will greatly reduce the cost of implementation of the proposed method.

Through the use of to enhance the sintering of more pure components than with clay and to a lesser extent increased temperature deformation products under load. However, increased interval between temperature deformation products under load and temperature firing, eliminating the marriage of firing deformations and cracks.

The method according to the invention was carried out as follows. Corundum refractory products prepared from charge, wt.%:

/tr>
granular oxide,
faction 3-1 mm35,0
faction 1-0 mm36,0
it electrocorundum,
fractions of less than 0.09 mm29,0
it is a mixture of oxides of silicon and aluminum
in the eutectic ratio, wt.%:
94,5 SiO2and 5.5 Al2About3,
fractions of less than 0.09 mm2,0-4,0 (over 100%)
an aqueous solution of lignosulfonate technical
density 1.18 g/cm33.9 to 4.5 (over 100%).

Originally prepared suspension specified it is a mixture of oxides in an aqueous solution of lignosulfonate technical, which are thoroughly mixed. The obtained suspension was moistened granular corundum, after which he introduced it corundum component, and again stirred.

The product was molded at the pressure of 70 N/mm2, was dried and annealed at temperatures of 1200, 1400 and 1500°C. the dwell Time at the final temperature was 6 hours.

After firing has been examining products to identify defects firing. The inspection marriage roasting deformations and cracks are not detected.

Physico-ceramic properties of corundum refractories was determined on the samples according to the existing Standards and methodologies. Performance properties given in the table.

The table shows that the products are manufactured according to the invention have a high strength (more than 50 N/mm2at temperatures of 1200, 1400 and 1500°C. High the strength indicates the sintering products. Obtained in a known manner products under the same firing temperature have a low resistance (less than 30 N/mm2which suggests there is insufficient sintering and the need to further increase the firing temperature. The onset temperature deformation under load of the products produced by the proposed method, 10-20°With higher than those of products obtained by the method prototype. Other properties satisfy the requirements of THE 14-8-556-87*(*Reference. Refractory products, materials and raw materials. - M.: metallurgy, 1990. p.63)requirements corundum products of similar composition containing not less than 90% of Al2About3. The error rate is reduced by 9-11%.

Thus, the proposed method allows to reduce energy consumption in the production of corundum refractories by reducing the temperature of firing 200-500°while maintaining the required level of properties shown to corundum refractories, as well as to increase the heat distortion temperature under load and to eliminate the marriage of porcelain.

* σ bending

The method of manufacture of corundum refractory products comprising preparing a mixture by wetting granular corundum suspension component activating multicourse additives in an aqueous solution of lignosulfonate technical and subsequent mixing with the tone of molotow corundum component, the products are molded from the resulting mixture, drying and firing, characterized in that in the preparation of the charge as the activating multicourse additives used it is a mixture of oxides of silicon and aluminum in the eutectic ratio, wt.%: 94,5 SiO2and 5.5 Al2About3in the quantity of 2-4 wt.% from the overall content of corundum components, and the roasting of products is carried out at a temperature of 1200-1500°C.



 

Same patents:

FIELD: refractory articles for manufacturing of ceramic units operating at 1800°C.

SUBSTANCE: claimed raw mixture contains (mass %): fused corundum of grade <0.05 mm 45-50; fused mullite of grade 0.4-1 mm 15-22; ethyl silicate 1-2: and additionally it contains fused corundum of grade 0.5-0.8 mm 20-25; fused mullite of grade 1.0-2.5 mm 5-8; and graphite 2-5. Method of present invention makes it possible to increase refractoriness up to 1900°C and simultaneously to decrease backing temperature to 1450-1550°C.

EFFECT: raw mixture for production of refractory articles with increased refractoriness.

2 tbl

FIELD: manufacturing refractory materials.

SUBSTANCE: refractory packing mass comprises, in mass %, 51-61 of grain corundum, 32-43 of the mixture of fine corundum and refractory clay, and 5.5-7.5 of orthophosphoric acid.

EFFECT: enhanced strength.

3 cl, 1 tbl

FIELD: non-iron metallurgy, in particular cladding of metal plunge.

SUBSTANCE: claimed refractory concrete contains (mass %): corundum mass 82-85; high-aluminous cement 4-5; electrical filter dust from silicium production 4-5; phosphoric acid 2-3; and water 3-4. Method for cladding manufacturing using the said concrete includes former installation into plunge; charging of refractory concrete into space between plunge internal wall and former, vibratory compaction, and two-step drying: at first at 20-250C for 5-7 days and then by graduated heating and drying. Namely, at first cladding is heated up to 1500C with rate of 6-80C/h and kept for 9-11 h; then cladding is heated up to 4000C with rate of 13-150C/h and kept for 14-16 h; then cladding is heated up to 6000C with rate of 20-220C/h and kept for 10-12 h. Cladding obtained by claimed method stands on silicium refining plunge up to 90 air thermal cycling.

EFFECT: cladding of improved strength.

2 cl, 4 tbl, 1 ex

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The invention relates to techniques for the production of ceramic products used as agrarias in furnaces periodic and continuous action in ceramic, refractory, abrasive, porcelain and other industries

The invention relates to refractory industry

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The invention relates to the production of refractory products, and in particular to compositions used for the manufacture of agrarias (kapseli, boxes, cups, boats, and other) during firing of ceramic products, including ceramic long rods complex configuration required for the casting of superalloy, such as blades for aircraft engines

FIELD: non-iron metallurgy, in particular cladding of metal plunge.

SUBSTANCE: claimed refractory concrete contains (mass %): corundum mass 82-85; high-aluminous cement 4-5; electrical filter dust from silicium production 4-5; phosphoric acid 2-3; and water 3-4. Method for cladding manufacturing using the said concrete includes former installation into plunge; charging of refractory concrete into space between plunge internal wall and former, vibratory compaction, and two-step drying: at first at 20-250C for 5-7 days and then by graduated heating and drying. Namely, at first cladding is heated up to 1500C with rate of 6-80C/h and kept for 9-11 h; then cladding is heated up to 4000C with rate of 13-150C/h and kept for 14-16 h; then cladding is heated up to 6000C with rate of 20-220C/h and kept for 10-12 h. Cladding obtained by claimed method stands on silicium refining plunge up to 90 air thermal cycling.

EFFECT: cladding of improved strength.

2 cl, 4 tbl, 1 ex

FIELD: manufacturing refractory materials.

SUBSTANCE: refractory packing mass comprises, in mass %, 51-61 of grain corundum, 32-43 of the mixture of fine corundum and refractory clay, and 5.5-7.5 of orthophosphoric acid.

EFFECT: enhanced strength.

3 cl, 1 tbl

FIELD: refractory articles for manufacturing of ceramic units operating at 1800°C.

SUBSTANCE: claimed raw mixture contains (mass %): fused corundum of grade <0.05 mm 45-50; fused mullite of grade 0.4-1 mm 15-22; ethyl silicate 1-2: and additionally it contains fused corundum of grade 0.5-0.8 mm 20-25; fused mullite of grade 1.0-2.5 mm 5-8; and graphite 2-5. Method of present invention makes it possible to increase refractoriness up to 1900°C and simultaneously to decrease backing temperature to 1450-1550°C.

EFFECT: raw mixture for production of refractory articles with increased refractoriness.

2 tbl

FIELD: refractory materials.

SUBSTANCE: invention relates to manufacture of corundum refractory articles based on mullite-corundum binder and used in linings of heat assemblies employed in variant industry fields. Method of invention comprises preparation of blend by way of moistening grainy corundum constituent with suspension of activating mullite-forming additive in industrial-grade lignosulfonate aqueous solution followed by mixing with finely ground corundum constituent, formation of articles from thus prepared blend, drying thereof, and firing at 1200-1500°C. Activating mullite-forming additive is finely ground silica/alumina mixture in eutectic weight ratio 94.5/5.5, respectively, used in amount 2-4% of the weight of total content of corundum constituents.

EFFECT: reduced power consumption on production of corundum refractory products due to lowered (by 200-500°C) firing temperature and reduced refuse.

1 tbl

FIELD: refractory industry, in particular production of thermal shields based on refractory oxides and silicate-forming additives.

SUBSTANCE: claimed method includes preparation of powdered, multifractional ceramic mixtures, including fused corundum and thermoplastic binder additive; preparation of thermoplastic slurry; injection molding into metal mould; binder removing; and finished burning at 1650°C for 4-5 hours. Fine mixture of kaolin and clay in ratio of 1:1 and in amount of 15-20 % is introduced into sphere-like fused corundum powders, wherein ratio of specific surfaces of fused corundum powder and fine mixture is from 0.05 to 0.07. Thermoplastic binder contains (mass %): paraffin 75-82; wax 3-5 and fine-crystalline paraffin 15-20. Thermoplastic binder is removed on substrate from capillary porous permeable material, in three step, by holding for 1-2 h at wax, paraffin and fine-crystalline paraffin liquidus temperatures.

EFFECT: refractory articles of improved quality.

5 cl, 1 ex, 2 dwg

FIELD: refractory materials industry; charges and the methods of production of the corundum refractory materials.

SUBSTANCE: the invention is pertaining to the refractory materials industry and may be used at manufacture of the high-density special-purpose corundum refractory materials for the critical blocks of the lining of the heat aggregates working in the conditions of the variable oxidative-reducing or the reducing gas medium. The technical result of the invention is the increased heat resistance, erosion resistance and the reduced porosity, reduction of the reject during their heating and the following cooling within the whole temperature range of the furnace operation. The charge for production of the corundum refractory materials includes the components in the following ratio (in mass %): the filling material: the electrocast corundum of the fraction of 3-1 mm - 20-25 %, the electrocast corundum of fraction of 1-0.5 mm - 30-35 %, the electrocast corundum of fraction of 0.5-0.1 mm - 20-25 %; the binding component of the charge: aluminum oxide with the particles size of less than 5 microns - 15-20 %, aluminum oxide dispersible with the particles size of less than 1 micron containing magnesium oxide with the particles size of less 1 micron - 5-10 %; the binding material - 2.5-2.8 % of the dry charge. At that the charge contains: AL2O3 - no less than 99.0 %, Fe2O3 - no more than 0.05 %, SiO2 - no more than 0.5 %. As the binding material use hydrosolAL2O3 in the combination with lignosulfonate and the polyvinyl alcohol taken in the ratio of 70-74.8 : 25-29 : 0.2-1,0 %. The method of manufacture of the corundum refractory materials includes: the charge preparation by mixing of the components of the filling material with the binding component, the subsequent connection with the refractory bond, molding of the products including the filling of the charge in the press-mould, pressing, the seasoning, the drying, the roasting and refrigeration. All the stages of the products molding are conducted under action of the vibrating tool mounted directly on the press mold body. At that at the stage of the charge filling the amplitude of the vibrations is set equal to 0.5-1 mm and the vibrations intensity - λ < 1, the products pressing is conducted at the pressure of 80-100 MPa, the amplitude of the vibrations of 0.25-2 mm and at the vibrations intensity - λ > 1, the release of the products from the moulds is exercised at the amplitude of the vibrations of 0.1-0.5 mm and the vibrations intensity - λ < 1. The roasting conduct in the batch furnace at the rarefaction of no less than 50 Pa during its heating up to the temperature of 1730-1750°C, and refrigeration of the refractory materials is conducted in the furnace simultaneously with its cooling-down by the natural convection till achievement of the internal temperature of the furnace of 600°C and further - till the final cooling-down with the help of the forced feeding of the atmospheric air from the furnace section.

EFFECT: the invention ensures the corundum refractory materials increased heat resistance, erosion resistance, reduced porosity, reduction of the reject during their heating and cooling.

9 cl, 3 tbl, 1 ex

FIELD: refractory material manufacture, possibly production of neutralizer of slag in converters and plants for out-of-furnace steel evacuating.

SUBSTANCE: charge for producing slag neutralizer on base of alumina filler prepared from technological alumina with additive of boron compound contains next relation of ingredients, mass %: technical-grade alumina or aluminum hydroxide and technical-grade alumina with fraction size less than 0.063 mm, 60 - 68; non-organic plasticizer, 5 - 20; organic adhesive, 1 - 5; binder, 6 -15. Charge filler contains α -alumina at relation of technical-grade alumina to α-alumina (1 : 2) - (2 : 1), boric acid is used boron compound at relation of charge components, mass %: alumina filler with fraction size less than 3 mm, 40 -80; boric acid, 0.5 -3; adhesive composition, 19.5 - 57.

EFFECT: preparation of charge for slag neutralizer on base of active form of alumina with structure having target strength at room temperature with high permeability relative to melt slag, lowered temperature for heat treatment of material.

1 tbl

FIELD: steelmaking industry.

SUBSTANCE: invention relates to manufacturing mullite-corundum crucibles to cast steel and refractory alloys, cooled blades of aircraft engines, as well as refractory saggers. Method according to invention comprises grinding alumina GK in presence of hydrophobizing liquid 136-41 in amount 0.018-0,020%, preparing aqueous molding mass from molten mullite powders, electrocorundum , and ground alumina GK, seasoning mass and additionally mixing it, vibrationally casting blanks, drying and firing them. Composition of molding mass presented in the form of size fraction is the following, (mm) - wt %: molten mullite (0.8-4.0) - 20.0-28.0, (0.2-0.8) - 6.5-8.0; electrocorundum (0.8) - 4.7-5.3, (0.5-0.63) - 2.8-3.1, (0.32-0.4) - 11.7-12.4, (0.20-0.25) - 1.8-2.2, (0.01-0.16) - 14.0-15.0; alumina GK 30.0-34.0; hydrophobizing liquid 136-41 (above 100%) 0.0115-0.0135; and water (above 100%) 6-8.

EFFECT: increased vibrational mobility of molding mass, strengthened blanks, and increased strength, density, and heat resistance of articles.

8 cl, 3 ex

FIELD: manufacture of building materials.

SUBSTANCE: invention relates to technology of production of refractory materials, which can be used as protective coatings against corrosive media during process heatings and in parts and intermediate products manufacturing processes. Composition according to invention contains, wt %: electrocorundum 35.2-52.0, Oxydal 4.0-6.0, kaolin 0.8-1.2, "Ruzin 12" 2.0-3.0, alumino-magnesium phosphate 18-27, and water 20-30.

EFFECT: improved quality of coatings.

3 ex

FIELD: production of filtering foamceramic materials used in metallurgy for filtration of metals melts.

SUBSTANCE: for preparation of ceramic slip, use is made of refractory mixture containing the following components, mass-%: fractionated synthetic corundum, 35.2-52.8; finely-dispersed oxidal, 4.0-6.0; kaoline, 0.8-1.2; alumo-chromophosphate binder including metal element contained in refractory filler, 36-54; aqueous acryl emulsion of 45-52-% concentration, 4.0-6.0. Aqueous emulsion is prepared from alumochromophosphate binder and aqueous acryl emulsion; dry mixture of synthetic corundum, oxidal and kaoline is introduced in aqueous suspension; ceramic slip is homogenized. Reservoir with blank made from organic foam is filled with definite amount of ceramic slip depending on thickness of ceramic straps in foamceramic filter; then, impregnation is carried out in mode of cyclic deformation till complete absorption of ceramic slip followed by drying and burning at temperature not below working temperature of foamceramic filters.

EFFECT: enhanced structural strength of sintered foam material.

2 tbl

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