SU1248996A1 - Method of manufacturing refractory articles - Google Patents

Description

t 1248996

The invention relates to refractory industry and can be used in the manufacture of refractory products for the lining of the most critical areas of high-temperature melting units of ferrous and non-ferrous metallurgy.

The purpose of the invention is to increase the high temperature strength and resistance to high iron slag, as well as reduce energy consumption for their manufacture.

The proposed method makes it possible to improve the quality of products by obtaining a homogeneous dispersed peric-15 lasochrome spindle and it is characterized by a high compaction ability during pressing and sintering activity. This is a batch of sn e1, so that when mixing a solution of 20 chromic acid salt - magnesium dichromate with magnesium oxide or a material that forms during calcination of magnesium oxide, a mixture is obtained, representing a humor-containing oxide material by means of low-temperature

homogeneous mixture.

not

calcining

due to the high-temperature calcination and the introduction of sintering additives that reduce the refractoriness of the material, it is possible to manufacture products with high resistance to impact at low energy consumption. Vision of slag – melt melt. At the same time, the density and thermal resistance of the products are maintained at a high level.

g

The proposed method is carried out as follows.

Magnesium dichromate is dissolved in water to obtain a 50% solution, and magnesium oxide or a material that forms magnesium oxide during heat treatment is introduced into the solution: caustic magnesite, magnesium hydroxide, in a ratio providing a mass fraction

conglomerate of particles, bound-25 Cr, 0 in a calcined mixture of 15.25 and 35%.

The resulting mixture is subjected to heat treatment at 900-1200 ° C for 1.5 hours. Specific parameters of the heat treatment mode, as well as the mass fractions in the calcined mixtures and the type of granular aggregate used are shown in Table. one.

crystal hydrates of dichromate and magnesium chromate. In the process of calcining the mixture of crystalline hydrates, stepwise, as they are heated, they dissociate with the release of water vapor, as well as atomic oxygen during the transition of hexavalent chromium to trivalent, eventually forming submicroscopic particles of magnesium chromite (MgO.

), which has a high sintering activity due to multi-stage thermal activation. The high heating rate favors the formation of a limited amount of embryonic magnesium chromite and MgO crystals and their preferential growth at the final calcination temperature, which ensures the polydispersity of the powder and its good compressibility. In this case, the final calcination temperature depends on the content of magnesium chromite in the mixture, which has a lower particle growth rate than in MgO, and increases from 900 to

share. Content

1200 C when changing the mass in the mixture from 15 to 35%.

in the range from 15 to 35%, it determines the optimum content of the chromospindle phase in the bond and its high resistance to high-iron shpak.

Getting active to sintering and ho) eosho pressing high-purity

magnesium chromium oxide material by low temperature

homogeneous mixture.

not

calcining

due to the high-temperature calcination and the introduction of sintering additives that reduce the refractoriness of the material, it is possible to manufacture products with a high resistance to impact at low energy consumption. Vision of slag – melt melt. At the same time, the density and thermal resistance of the products are maintained at a high level.

g

The proposed method is carried out as follows.

Magnesium dichromate is dissolved in water to obtain a 50% solution, and magnesium oxide or a material that forms magnesium oxide during heat treatment is introduced into the solution: caustic magnesite, magnesium hydroxide, in a ratio providing a mass fraction

5 Cr, 0 in the calcined mixture 15.25 and 35%.

0

five

0

five

0

five

The resulting mixture is subjected to heat treatment at 900-1200 ° C for 1.5 hours. Specific parameters of the heat treatment mode, as well as the mass fractions in the calcined mixtures and the type of granular aggregate used are shown in Table. one.

In order to obtain comparative data, products are prepared in a manner known per se.

The dispersed component is made by burning magnesium dichromate at 1500 ° C for 1.5 h with subsequent grinding and mixing with titanium-magnetite concentrate, taken in an amount of 4% (Example 10).

The dispersed component is mixed with the granular material of the basic composition of the mixture for the manufacture of refractories contains, in May.%: The material of the basic composition of the fraction 3-0 mm 60; chromium-type concentrate fracdai and 1-0 mm 10 and dispersion component 30. As a granular material of the main composition, sintered magnesite is used (examples 1-7, 10), magnesium oxide (example 9), and clinker obtained by briquetting and firing sintering the dispersed component prepared by the proposed method (example 8).

A temporary binder, a sulphite yeast brew, is added to the mixture and the products are pressed at a pressure of 150 MPa, which are then calcined at

3

 in 11rom1 of the tunnel tunnel furnace.

Properties of products obtained by the proposed and known methods are given in table. 2

Stacking resistance of the products is determined by changing the volume of samples with a diameter of 30 mm and a height of 35 mm after they are kept in the pshak melt of electric arc melting of steel for 2 hours at. Slag composition, wt.%: CaO 14.7; SiO 24.5; MpO 9.8; FeO 31.4; , 17.5; 3.5; MgO 7.5.

From the above data, it follows that the products manufactured by the inventive method are substantially superior in. the quality of the product, made by a known method (example 10, especially for high temperature strength (1.5-2 times) and resistance to slag erosion (1.3-1.9 times). This refers to products made from

Magnesium oxide

24.6

Caustic magnesite25,4

3 4

Magnesium hydroxide

produced with both sintered magnesite and sintered magnesia (example 9) and a magnesium chrome-containing briquette-clinker (example 8) in the granular component.

In addition, the proposed method can significantly reduce energy consumption by reducing the temperature and duration of heat treatment of the dispersed component of products. The reduction in energy consumption, for example, during the heat treatment of the material in the semi-industrial silicon furnace, is 30-35%.

Thus, the proposed method provides a reduction in energy consumption in the manufacture of products, an increase in their quality, which causes high resistance of refractories in the most critical areas of the lining of ferrous and nonferrous metallurgy smelters.

Table 1

24.6

1050

25-30

105025-30

105025-30

105025-30,

1050 25-30

90025-30

1200-25-30

Speckled magnesite

Continuation of table 1

Claims (1)

METHOD FOR PRODUCING REFRACTORY PRODUCTS by mixing granular material of the main composition with a dispersed component, obtained by heat treatment of magnesium chromate, pressing and firing products, characterized in that, in order to increase the high temperature strength of products and resistance to high-iron fenders, as well as reduce energy consumption for manufacturing of products, before heat treatment, the chromic acid salt of magnesium is dissolved in water, magnesium oxide or a material forming magnesium oxide is introduced into the resulting solution treatment, in an amount providing a mass fraction Cr ₂ 0 ₃ in the dispersion of from 15 to 35%, and heat treatment is performed at a temperature of 900-1200 ° C with a temperature elevation rate of 25 deg / min. SU 1248996 A1