RU2198150C2 - Blend for manufacturing chamotte refractory materials - Google Patents

Abstract

FIELD: manufacture of building materials. SUBSTANCE: blend contains 65-80% chamotte, 19.5-34% refractory clay, and 0.5-1.0% of naturally occurring topaz as caking additive. Topaz rock finely divided to particle size below 0.063 mm, in order to be uniformly distributed throughout the bulk of blend, is added together with clay clinker required to moisten blend until moisture content attains 6-8%. Products are formed by dry-pressing technique at pressures 60-80% and then baked at 1320-1350 C. EFFECT: increased mechanical strength, heat resistance, and refractoriness of products at lower baking temperature due to intensified caking of clay-chamotte compositions and higher content of needled mullite. 3 tbl

Description

 The invention relates to the production of refractory materials of aluminosilicate composition and can be used for the manufacture of, for example, fireclay refractories.

 Known mass for fireclay refractories, including a cleaner and clay.

 The disadvantage of this mass is the increased firing temperature of the products and low strength / Vakalova T.V., Luzin A.V., Pachin V.N., Vereshchagin V.I. Improving the quality of chamotte products from Troshkovskiy clays using intensive dispersion methods. Complex use of mineral raw materials, 1986, 11, p. 81-83 /.

The disadvantages of chamotte masses for normal and ladle refractories are the low compressive strength due to insufficient sintering of the clay binder at the applicable firing temperatures (1320-1350 ^o С), attempts to intensify the sinterability by introducing soda additives adversely affect the thermomechanical properties of the products / Popov A.D. Chamotte products from clays of the Troshkovsky deposit. Proceedings of the Eastern Institute of Refractories. Metallurgy, 1966, no. 6, p. 22-36 /.

The closest is the mass for the production of fireclay refractories, including these components, wt.%:
Otoshitel (chamotte) - 70.0-50.0
Refractory clay - 40.5-24.0
Petrolatum (plasticizing additive) - 5.5-4.0
Bentonite (sintering additive) - 4.0-2.0
The disadvantage of this mass is the relatively low strength of the products, which is due to a number of reasons, including the burnout of petrolatum, which disrupts the contact of the chamotte grains with the dispersed part. The presence of bentonite as a sintering additive is insufficient to provide a higher level of strength properties / A. S. 298565, MKI C 04 V 33/16 /.

 The objective of the invention is to increase the mechanical strength, heat resistance and fire resistance of products while reducing the firing temperature due to the intensification of the sintering process, which is ensured by the addition of natural topaz introduced with topaz rock.

The proposed refractory mixture for the manufacture of fireclay refractories contains in its composition, wt.%:
Fireclay - 65-80
fractions of 3-2 mm 20-30%
fractions 2-0.5 mm 20-30%
fractions less than 0.5 mm 50%
Refractory clay - 19.5-34
Natural topaz (sintering additive) - 0.5-1.0
A decrease in the amount of added topaz additive less than 0.5% necessitates an increase in the firing temperature to intensify the sintering process, an increase in the topaz content of more than 1.0% slows down the sintering process and, accordingly, reduces the operational properties of refractory products due to an increase in the amount of topaz released during decomposition gaseous fluorine compounds not assimilated by the glass phase and loosening the resulting ceramic structure.

 An example of the manufacture of fireclay refractories.

 Preparation of raw materials is carried out in a separate way. Clay clay, for example Troshkovskaya, is crushed in a disintegrator or in runners before passing through a 0.5 mm sieve - at least 70%. A purifier from the same clay with water absorption of not more than 3% is prepared in the traditional way by grinding in the necessary equipment, followed by isolation of the desired fraction. A topaz-containing rock with a topaz content of more than 50% is finely ground to a size less than 0.063 mm, for example, in a ball mill. The chemical composition of the raw materials is given in table. 1.

To prepare the mass, the cross-linked fireclay scrubber with a fraction of 3-2 mm - 20-30%, 2-0.5 mm - 20-30%, less than 0.5 mm - 50% is moistened to a moisture content of 6-8% with a clay slip, density 1, 25 g / cm ³ , representing a mixture of the composition (%): clay - 35, calcium lignosulfonate (CSP) - 10 (per dry matter), water - 55, which also contains prepared topaz-containing rock in quantities that ensure the content of topaz itself 0, 5-1% of the mass of the mixture in terms of dry matter (mass compositions are given in table. 2). This method of introducing a sintering additive provides a uniform distribution throughout the entire volume of chamotte.

Then, the resulting mixture of moistened detergent with a sintering additive is mixed with prepared clay binding. This creates a close contact between the grains of the cleaner, activating additive and a bunch. After homogenization from the charge by known technological methods, the semi-finished product is pressed at a pressure of at least 60-80 MPa (depending on the degree of refinement). The firing is carried out at 1320-1350 ^o C with a holding time of at least 2 hours. Lowering the firing temperature less than 1320 ^o C does not ensure the completeness of the sintering process and the formation of the refractory structure, firing at temperatures above 1350 ^o C is impractical for economic reasons due to the increase in energy costs. The properties of the calcined products are given in table. 3.

 Topaz in quantities of 0.5-1.0% activates the process of mullite formation and sintering of compositions with a regular increase in shrinkage, a decrease in water absorption, an increase in product strength, heat resistance and fire resistance. The mineralizing effect of topaz on the process of mullite formation is reduced to the formation of mullite nuclei, which play the role of crystallization centers for secondary mullite. The fluorine released during the thermal decomposition of topaz is absorbed by the formed silicate melt and affects its rheological and reaction properties, creating favorable conditions for the dissolution of the primary mullite and recrystallization of the secondary, lowering the temperature of its synthesis, increasing the yield and improving the structure. An increase in the content of secondary needle mullite reinforces the structure and provides an increase in compressive and bending strength, heat resistance, and fire resistance.

Claims (1)

A mixture for the manufacture of chamotte refractories, including a chamotte clarifier, clay and a sintering additive, characterized in that the chamotte is moistened to a moisture content of 6-8% with a clay slip, which is a mixture of the composition, wt.%: Clay 35, calcium lignosulfonate 10 per dry matter, water 55, and as a sintering additive, natural topaz is used in the following ratio of charge components, wt.%:
Fireclay - 65-80
fractions of 3-2 mm 20-30%
fractions 2-0.5 mm 20-30%
fractions less than 0.5 mm 50%
Refractory clay - 19.5-34
Natural Topaz - 0.5-1.01

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