RU2260573C2 - Spinel refractory material - Google Patents

Abstract

FIELD: metallurgy; production of spinel refractory material for lining smelting furnaces.

SUBSTANCE: the invention is pertaining to the field of metallurgy, in particular, for production of spinel refractory material used for lining smelting furnaces, for example, for smelting of aluminum alloys. The mass for production a spinel refractory material consists of (in mass %): an under-earth - 3-5, a sintering additive in the form of a mix of boric acid and sodium tripolyphosphate taken in the ratio from 1:9 up to 9:1 - 4.5-6.5, a temporary binder - 2-3 and a melted aluminum-magnesia spinel - the rest. It is preferable to use aluminum-magnesia spinel containing fractions of <0063 mm within the limits of 30-40 mass %. The sintering additive and the fine grain composition of aluminum-magnesia spinel ensure a good sintering of the refractory mass and production of a dense refractory material with a low accessible porosity and a high mechanical strength. The refractory material is inertial to a melt of metal and is not impregnated with it, that ensures parallax purity of the smelted metal and eliminates metal loss with lining.

EFFECT: the invention ensures production of a dense refractory material with a low accessible porosity, a high mechanical strength, a good mass sintering, a parallax purity of the smelted metal excluding the metal loss with lining.

2 cl, 2 tbl

Description

The invention relates to the refractory industry, in particular to the production of refractory products for the lining of melting furnaces, such as melting aluminum alloys.

Known refractories based on fused aluminum-magnesium spinel, for example, the invention according to the patent of the Russian Federation No. 2068824, C 04 B 35/443, 1996 [1], and.with. USSR No. 421668, C 04 B 35/04, 1974 [2]; published application of the Russian Federation No. 98120869, C 04 B 35/043, 2000 [3].

By the set of common essential features, the closest to the patentable one can be attributed spinel refractory obtained from the refractory mass according to the RF patent No. 2068824, C 04 B 35/443, 1996 [1].

It contains fused alumomagnesium spinel 77-93 wt.%, Corundum 5-15 wt.% And sintering additives in the form of boric acid 1-4 wt.% And complex boron-containing oxide or refractory clay 1-4 wt.% As a refractory filler.

The main disadvantages of this refractory are high open porosity, which in service leads to increased metal impregnation and loss of metal with lining, and insufficient mechanical strength.

An object of the present invention is to provide a stable refractory based on fused aluminum-magnesium spinel for lining melting furnaces, in particular, melting aluminum alloys.

The technical result consists in reducing open porosity, increasing the density and mechanical strength of spinel refractory.

To achieve this, according to the claims, the spinel refractory is obtained from a refractory mass, including fused aluminum-magnesium spinel, refractory clay, a sintering additive in the form of a mixture of boric acid and sodium tripolyphosphate in a ratio of 1: 9 to 9: 1 and a temporary binder in the following ratio of components , wt.%:

fire-clay 3-5 specified sintering additive 3-8 temporary binder 2-3 fused aluminum-magnesium spinel rest

The essence of the invention lies in the fact that the introduction into the refractory mass of a sintering additive in the form of a mixture of boric acid and sodium tripolyphosphate provides it with high molding properties and good sintering at relatively low temperatures. This is achieved by giving sodium tripolyphosphate the effect of \ fluidity \ of a fine fraction of fused alumino-magnesian spinel and its maximum filling of voids between large grains, as well as by the physicochemical interaction of the components during the firing of the molded products. Boric acid and sodium tripolyphosphate in the initial stage of firing form a melt in the Na ₂ OB ₂ O ₃ -P ₂ O _{5 system} , which intensively interacts with the clay degeneration product (metakaolinite Al ₂ O ₃ · 2SiO ₂ at a temperature of 1000-1100 ° С) forming a multicomponent melt in the system Na ₂ O-B ₂ O ₃ -P ₂ O ₅ -Al ₂ O ₃ -SiO ₃ . With increasing firing temperature to 1100-1270 ° C, the most dispersed part of the mixture dissolves in this melt, causing liquid sintering of the mass with the formation of silicate 2MgO · SiO ₂ + CaO · MgO · SiO ₂ and a glass phase of complex composition.

With the introduction of the specified sintering additive of less than 3 wt.% Or the content of sodium tripolyphosphate in the mixture of less than 1 with respect to boric acid, the grain packing density in the mass decreases and an insufficient amount of primary melt is formed, which does not provide good sintering of the mass and low porosity of the products. A content of sodium tripolyphosphate in the mixture of more than 9 with respect to boric acid or the introduction of a sintering additive of more than 8 wt.% Leads to the flowability of the raw products and the formation of excess low-melting glass phase, which reduces the resistance of the refractory.

In accordance with claim 2 of the formula, fused aluminum-magnesium spinel has a grain composition with a fraction content of less than 0.063 mm in the range of 30-40 wt.%. The established amount of the finely ground fraction makes it possible to obtain a dense, finely porous refractory structure during sintering of the mass, mainly with closed pores.

The enlargement of the grain composition increases the open porosity of the products and the impregnation of the refractory metal.

As a temporary binder, technical lignosulfonate, phenol-formaldehyde resin of the VRB brand, liquid bakelite of the BZh-3 brand, and unsaturated polyester resin PN-1 can be used.

Spinel refractories are made as follows.

Applicable materials: fused aluminomagnesia spinel of a thinned grain composition with a content of fractions: less than 0.063 mm 38 wt.%, Fractions 3-2 mm 12 wt.% And fractions 2-0 mm 50 wt.% Produced by OJSC \ Pervouralsky Dinas Plant \ (TP 202 -0-5-2002), refractory clay, grade NU-2 (TU 14-8-336-80), boric acid (GOST 18704-78), sodium tripolyphosphate (TU 48-0328-25-94), technical liquid lignosulfonate (TU 54-028-00279580-97).

To obtain a refractory molding composition, these components were used in the amounts given in the claims.

The components are dosed, loaded into the mixer, mixed in a dry state, then technical liquid lignosulfonate and water are added to a moisture content of 3.7-4.2 wt.%, And the mass is mixed again.

The finished mass is unloaded from the mixer and fed to the press for molding products. The molded products are dried and fired at temperatures up to 1300 ° C.

Examples of compositions of the refractory mass for the manufacture of spinel refractory are shown in table 1, example 4 relates to a prototype. The properties of spinel refractory are shown in table 2. The definition of property indicators was carried out:

- open porosity and apparent density according to GOST 2409-95;

- compressive strength according to GOST 4071.1-94;

- linear growth according to GOST 5402.1-2000.

As can be seen from the table, patented spinel refractory has a density of at least 2.70 g / cm ³ , porosity of not more than 20% and mechanical compressive strength of more than 60 N / mm ² , which is higher than the prototype.

The results of industrial tests in a gas reflective aluminum smelting furnace showed good lining resistance. After a year of operation of the furnace, the spinel refractory lining has no cracks or erosion, is easily cleaned of metal deposits, there is no impregnation and interaction of the molten metal with the refractory, which ensures the purity of the melted metal and eliminates metal loss with the lining.

Thus, a stable spinel refractory was created for lining of melting furnaces, in particular, melting of aluminum alloys, which was confirmed by the results of industrial tests.

Sources of information

1. RF patent No. 2068824, C 04 B 35/443, 1996.

2. A.S. USSR No. 421668, C 04 V 35/04, 1974.

Published application of the Russian Federation No. 98120869, C 04 B 35/043, 2000.

Table 1 Mass components The inventive composition Famous Composition Content, wt.% 1 2 3 4 Fire-clay 3 3 2 2,5 A mixture of boric acid and sodium tripolyphosphate in a ratio of 1: 1, wt.% 4 A mixture of boric acid and sodium tripolyphosphate in a ratio of 1: 9, wt.% 5 A mixture of boric acid and sodium tripolyphosphate in a ratio of 9: 1, wt.% 4 Technical liquid lignosulfonate 3 3 3 - Fused Aluminum Magnesium Spinel 90 89 91 85 Corundum - - - 10 Boric acid - - - 2,5

table 2 Indicators Compositions Famous 1 2 3 4 Open porosity,%: 19.7 18.5 20,0 20.6-23.1 Apparent density, g / cm 2.77 2,8 2.70 2.61-2.68 The limit of compressive strength, N / mm ² 70.3 60.7 60.0 32.6-48.6 Linear growth,% 0.2 0.3 0.1 0.1

Claims (2)

1. Spinel refractory obtained from a refractory mass, characterized in that it includes fused aluminum-magnesium spinel, refractory clay, a sintering additive in the form of a mixture of boric acid and sodium tripolyphosphate in a ratio of 1: 9 ÷ 9: 1 and a temporary binder in the following ratio of components, wt.%: Fire-clay 3-5 Specified Sintering Additive 4,5-6,5 Temporary binder 2-3 Fused Aluminum Magnesium Spinel Rest 2. Spinel refractory according to claim 1, characterized in that the fused aluminum-magnesium spinel has a grain composition with a fraction content of less than 0.063 mm in the range of 30-40 wt.%.