RU2052420C1 - Method of refractory article producing - Google Patents

Abstract

FIELD: refractory materials. SUBSTANCE: refractory mass containing, wt. -%: magnesite 5-15; finely divided mixture 20-35, and binder 5-20 has additionally olivinite 45-65. Finely divided mixture has the following composition, wt. -%: magnesite 30-70; olivinite 15-35; talc 15-35. Binder has, wt. -%: ethyl silicate 20-40; dimethylketone 4.5-12; 5% solution of phosphoric acid 0.3-1.5, and magnesium-chrome-phosphate binder 54.5-66.5. Charge components were mixed for three stages, refractory mass is treated at 700-900 C and kept at maximal temperature for 1 hr. EFFECT: increased moisture resistance, metal- and slag-stability of refractory mass. 4 tbl

Description

 The invention relates to the industry of refractories, and in particular to the technology of refractory masses for the manufacture of refractory products, and can be used for lining metallurgical units, for example, in the manufacture of ladle and nesting bricks for steel pouring ladles.

 Known refractory mass [1] for lining steel casting ladles, containing as a binder aluminochromophosphate binder in the following ratio of components, wt. pyrophyllitis 10-50; alumochromophosphate binder 10-15; fireclay the rest.

Products do not have a sufficiently high strength at low processing temperatures of 200-250 ° ^C. However, these refractories have relatively low metal and shlakoustoychivost.

It is known to manufacture refractory products from a refractory mass [2] containing, by weight. fireclay 60-75; clay 6-10; aluminum chromophosphate binder 4-5; finely ground mixture 15-24. Introduced into the mixture is fine ground mass technical alumina and magnesite chromite at ^about 600-1500 C and forms a complex with refractory spinel clay, which together with mullite refractories reduces porosity, enhancing their resistance to aggressive environments.

However, products from this mass have sufficient strength only after heat treatment at a temperature of 1500 ^about C.

 The closest technical solution for the totality of the features of the claimed is a method of manufacturing non-fired products [3] from a refractory mass containing magnesite. chromite, a bunch and a finely ground mixture of the composition, wt. magnesite 60-70% chromite 10-20; bauxite chamotte 15-25, and a mixture of the composition, wt. urea-formaldehyde resin (UKS) 45-55; calcium-sodium salt of lingin-sulfonic acids 45-55, in the following ratio, wt. sintered magnesite 40-50; chromite 10-20; finely ground mixture 30-40; ligament 3-7.

The presence in the refractory mass of a finely ground mixture of the given composition increases the mechanical strength to 100 N / mm ² and the heat resistance to four heat shifts, but the water resistance of the refractory products obtained on its basis is very low. The low water resistance is explained by the fact that the urea-formaldehyde resin, which is part of the mass, dissolves in water. In addition, low metal and slag resistance was found when testing an industrial batch of unburned ladle in the lining of steel casting ladles at the Cherepovets Metallurgical Plant.

 After testing, the lining of this known mixture was highly impregnated with metal and slag from the surface layer of brick to a depth of 25-35 mm. The impregnated lining layer was then chipped off during further operation. The reduced metal and slag resistance can be explained by the increased porosity of the non-fired products and the composition of the binder containing urea-formaldehyde resin.

 These disadvantages of the known refractory masses for the manufacture of refractories dramatically reduce the effectiveness of their use in metallurgical units. In this regard, there is a need to increase the metal and slag resistance and moisture resistance of refractories in order to increase the service life of the lining.

 In the proposed technical solution, the refractory mass for the manufacture of refractory products, including magnesite, a finely ground mixture and a binder, additionally contains olivinite in the following ratio of components, wt. magnesite fraction 2-0 mm 5-15; finely ground mixture of a fraction of less than 0.063 mm 20-35; binder 40-65; olivinite fraction 3-0 mm 5-20.

 At the same time, the finely ground mixture is a mixture of ingredients of the following composition, wt. magnesite 30-70; olivinite 15-35; talcum powder 15-35.

 As a binder, a mixture of the composition, wt. ethyl silicate 20-40; dimethylketone 4.5-12; 5% phosphoric acid solution 0.3-1.5; magnesium chromophosphate binder 54.5-66.5.

The refractory mass is prepared in mixing runners in stages by mixing a finely ground mixture with a part of a binder, including ethyl silicate, dimethyl ketone and a 5% solution of phosphoric acid, then filler-magnesite and olivinite are introduced with stirring, moisten the remaining part of the binder with a magnesium-chromophosphate binder and finally again . From the thus prepared mass was compression-molded refractory samples and after drying is subjected to a thermal treatment at 700-900 ^C for 1 hour with an exposure at the maximum temperature. The introduction into the fine-ground component of the refractory mass of talc (3MgO · 4SiO ₂ · H ₂ O) in the above ratio promotes the formation of forsterite (Mg ₂ SiO ₄ ) in the binder of the refractory under service conditions in metallurgical units. This contributes to the formation of a dense and strong microstructure with a low coefficient of linear thermal expansion and thermal conductivity in the surface layer of refractory bricks. The mechanically strong, dense and heat-resistant forsterite lining thus obtained protects better from impregnation with metal and slag.

 In addition, one of the purposes of introducing an additive of talc in the finely ground part of the proposed refractory mass is to improve the molding properties of the refractory mass during extrusion of products.

The use of a binder of ethyl silicate provides an increase in water resistance of the inventive refractory mass. This is due to the fact that ethyl silicate interacts with chemically bound water released during the heat treatment of products at 700-900 ^о С and increases the water resistance of non-calcined products. In general, the proposed binder allows to obtain higher technical characteristics of refractory products in comparison with the known refractory products described above by analogue and prototype.

 In the table. 1-3 shows the compositions of the refractory masses, finely ground mixtures and ligaments for examples 1-6, and table. 4 physical and technical properties of refractory samples of the obtained refractory masses of the specified composition.

PRI me R 1. Take the components of the refractory mass of the claimed composition 1 (table. 1-3) containing, by weight. olivinite 40) fractions 3-0 mm); magnesite 55 (fractions 2-0 mm); finely ground mixture 35 (fractions less than 0.063 mm); binder 20. First, moisten the finely ground component with a part of the binder, consisting of a mixture of ethyl silicate, dimethyl ketone, 5% phosphoric acid solution and mix thoroughly for 3-5 minutes. Then, alternately the granular part of the mass of olivinite and magnesite and the remaining part of the binder are introduced alternately with magnesium-chromophosphate binder and once again finally mixed for 3-5 minutes. After that, standard samples are formed on a hydraulic press with a diameter of 38 mm and a height of 50 mm with a specific pressing pressure of 40-50 N / mm ² . The pressed samples were air-dried for one day and then in a drier to a residual moisture content of not more than 1%, and heat-treated in a batch furnace at 700 ^{° C} and held at maximum temperature for 1 hour. At the manufactured samples were determined the basic physical and technical characteristics which are given in table. 4.

PRI me R 2. Refractory mass of the claimed composition 2 containing, by weight. olivinite 45 (fractions 3-0 mm); 15 magnesite (fractions 2-0 mm fine ground mixture (fractions of less than 0.063 mm) 30; bundle 10, prepared as in Example 1. Made compression standard samples after drying to a moisture content of 1% was placed in an oven at a temperature of 800 ^{° C} and held at maximum temperature 1 h.

PRI me R 3. The refractory mass of the claimed composition 3, containing, by weight. olivinite (fractions 3-0 mm) 50; magnesite (fractions 2-0 mm) 10; finely ground mixture (fractions less than 0.063 mm) 25; ligament 15, prepared as in Example 1. The pressed samples were subjected after drying to thermal treatment at a temperature of ⁹⁰⁰ ° C isothermal exposure for 1 hour.

EXAMPLE EXAMPLE s 4 and 5. The refractory mass inventive formulations 4, 5 are prepared in analogy to example 1 and calcined in a batch furnace at 800 ^{° C} with an isothermal exposure for 1 hour.

PRI me R 6. Refractory mass of known composition 6 (prototype), containing, by weight. magnesite (fractions less than 0.5 mm) 45.0; chromite (fractions less than 1 mm) 15; fine mixture (fractions less than 0.063 mm) 35; and a binder 5, prepared analogously to example 1 and subjected to heat treatment at 1650 ^about With isothermal exposure of 4 hours

Data analysis table. 4 shows that test samples of refractory products manufactured by the proposed method ogneupopnoy from said mixture and heat-treated at a temperature of 700-900 ^o C, compared with known have higher water resistance, which was determined according to GOST 25.094-82. Their metal and slag resistance, determined by the crucible method, is also 1.5-2 times higher. Especially good results were obtained for samples of composition 2-4. In addition, a decrease in the amount of severely deficient magnesite and the replacement of chromite with olivinite significantly improve the technical and economic indicators of forsterite refractory products, reduce their cost and increase their competitiveness.

Claims (1)

METHOD FOR PRODUCING REFRACTORY PRODUCTS, including mixing a magnesite aggregate, a magnesite filler fraction of less than 0.063 mm and a binder, molding the products from the obtained raw material mixture and their heat treatment, characterized in that the magnesite filler is pre-mixed with fillers - talc and olivinite% in the ratio:
Olivinite - 30 - 70
Talc - 15 - 35
Magnesite - Else
and moisten with a mixture of components of a binder containing ethyl silicate, dimethyl ketone and a 5% solution of phosphoric acid, after which a magnesite aggregate of a fraction of up to 2 mm and optionally an olivinite aggregate of a fraction of up to 3 mm and then magnesium chromophosphate are introduced and final mixing is carried out to obtain a raw mixture containing , wt.%:
Specified Filler - 20 - 35
Olivinite aggregate fractions up to 3 mm - 40 - 65
Binder - 5 - 20
Magnesite aggregate fractions up to 2 mm - Else
wherein the binder contains, wt.%:
Ethyl silicate - 20.0 - 40.0
Dimethylketone - 4.5 - 12.0
5% phosphoric acid solution - 0.3 - 1.5
Magnesium Chromophosphate - 54.5 - 66.5,
and heat treatment is carried out with exposure for 1 hour at 700 - 900 ^o C.

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