CS251569B1 - Magnesium-aluminum spinner for lining furnaces for melting aluminum and non-ferrous metals - Google Patents

Abstract

The solution concerns a spinel mass, in which 55 to 85% is slag from aluminothermic metal production. It is a raw material with a high content of aluminum oxide and magnesium oxide, which are precipitated from the molten slag in the form of corundum and spinel. After adding slag to the tamping mass with the simultaneous addition of chemical and organic binders and following the prescribed procedure, the service life of induction furnace linings is extended compared to materials based on aluminosilicates.

Description

(54) Magnesium-aluminum spinning mass for lining furnaces for melting aluminum and non-ferrous metals

The invention relates to a spinel mass in which 55 to 85% is slag from aluminothermic metal production. It is a raw material with a high content of alumina and magnesium oxide, which are separated from the molten slag in the form of corundum and spinel. By adding slag to the ramming material while adding chemical and organic binders and following the prescribed procedure, the lifetime of induction furnace linings is prolonged compared to aluminosilicate-based compositions.

The present invention relates to a magnesium-aluminum spinel composition for the lining of induction and flame furnaces for melting aluminum and non-ferrous metals, the basic component of which is the magnesium-aluminum spinel obtained in the aluminothermic process of metal production.

At present, it is used for lining induction and flame furnaces for melting aluminum and nonferrous metals of grained chamotte to acid soils with a relatively high proportion of silica up to 65%. For the melting of copper and its alloys is often used a compound based on horseradish with a content of silica up to 97%. Both types of materials exhibit considerable disadvantages when used, such as, for example, reduction of silica with molten aluminum and thus lining disintegration, unfavorable dilatation changes during heating and cooling and the associated danger of cracking of the lining under improper operating conditions, low slag corrosion resistance, low. thermal conductivity, which is commonly associated with lower resistance of the lining to rapid temperature changes, low resistance to mechanical failure of the lining during metal insertion, against metal erosion, etc.

These disadvantages are partly overcome by the electrocorundum-based material, i.e. fused alumina. However, the disadvantage of electrocorundum is, besides the economic aspects, a high thermal elongation, which is disadvantageous in particular for the lining of large-capacity crucible furnaces for a capacity of more than 100 kg of metal.

The deficiencies of the known materials are overcome by the magnesium-aluminum spinel mass for lining induction and flame furnaces for melting aluminum and non-ferrous metals, according to the invention, the essence of which is that the basic component is aluminothermic slag with a grain size of up to 5 mm. The slag is composed of 80 to 90% magnesium spinel MgO.Al2O4. The remainder is crocrystalline corundum and enamel. In terms of chemical composition, it is a product with 72 to 6% alumina, 10 to 12% magnesium oxide, 2 to 4% silica. The remainder consists of calcium, titanium, iron, sodium, potassium and especially vanadium oxides in amounts up to 5 S. The advantage of this material is high thermal conductivity, low coefficient of thermal expansion without polymorphic transformations and low porosity of grains. The material prepared from this material is volume stable over a wide temperature range with excellent metal and slag corrosion resistance.

The properties of the composition can be further improved by additives for increasing the wettability angle of the metal, the epistel conductivity and the grain composition by the addition of graphite or finely ground graphite, ground alumina, very fine corundum grain, chromium oxide powder, magnesium oxide, silicon carbide. Appropriate workability of the lining mass and strength after drying is achieved by the addition of chemical binders such as phosphoric acid and their aluminum, ammonium, alkaline, organic adhesives such as dextrin, carboxymethylcellulose, sulfite / lye, aqueous dispersions of organic polymers such as polyvinyl acetate, polyacrylate dispersion -, liquid organic binder based on tar and the like.

l i luminoter. slag with a grain size of 0-3 mm white sectrocorund below 0.09 mm et alumina below 0.04 mm iha crystalline 10% by weight 15% by weight 10% by weight were moistened with a tar solution under the trade name INERTOL in an amount of 11 dm / 100 kg someone.

The mass was used for the lining of induction lastness:

refractory lorality lining

Deficient thermal expansion in the range of 20-1 000 ° C non-thermal conductivity at 100 ° C copper alloy melting furnace and achieved these higher than 1,800 ° C 19.5%

4.1.10 ^_6 / ° K greater than 3 W / m ° K

The lifetime of the lining increased 2.6x compared to the lining made of quartzite.

Example 2 aluminothermal slag 0-3 mm magnesite meal 0-0.09 mm ground alumina below 0.04 mm per 100 kg of the mixture aluminum admixtures dextrin powder 9% by weight kg 1 kg

The mixture was moistened with water to a consistency suitable for being rammed. It was used for lining crucible induction furnace for aluminum smelting. The following properties were achieved:

refractory porosity of the lining coefficient of expansion (temperature) in the range of 20-1 000 ° C coefficient of thermal conductivity at 100 ° C permanent length change by firing to 1 200 ° C

Example 3 0-3 mm aluminothermal slag 0-0.09 mm aluminothermal slag ground 0-0.06 mm alumina 0-0.04 mm alumina

The mixture was moistened with phosphoric acid for lining an induction furnace for melting zinc.

Achieved properties:

heat resistance porosity coefficient of thermal expansion in the range of 20-1 000 ° C coefficient of thermal conductivity at 100 ° C permanent length change by firing to 1 200 ° C

Example 4 aluminothermic slag with particle size up to 5 mm white electrocorundum with particle size up to 0,1 mm aluminum oxide technical with particle size up to 0,04 mm

The mixture was moistened with water and used for lining to achieve the following properties:

heat resistance porosity lining coefficient of thermal expansion in the range of 20-1 000 ° C coefficient of thermal conductivity at 100 C higher than 1 850 ° C 19,8%

4,5.10 ' ⁶ / ° K more than 3 W / m ° K + 0,1% more than 1,850 ° C 18,9%

3.6.10 ^_6 / ° K more than 4.5 W / m ° K + 0.1% wt% wt% induction furnace for melting copper alloys. They were higher than 1 800 ° C%

5,5.10 ' ⁶ / ° K greater than 2 W / m ° K% by weight 15% by weight 10% by weight 10% by weight concentration 55% acid, phosphoric and used

The mass can also be advantageously used for the production of unburned or baked refractory lining fittings for industrial furnaces or parts thereof.

Claims (6)

THE OBJECT OF THE INVENTION Magnesium-aluminum spinel mass for lining induction and flame furnaces for melting aluminum and non-ferrous metals, characterized in that the basic constituents comprise 55 to 85% by weight of aluminothermic slag with particle size up to 5 mm and 15 to 45% by weight of ceramic additives with particle size up to 0.09 mm. 2. The magnesium-aluminum spinel mass of claim 1, wherein the ceramic additives are electrocorundum, ground, technical alumina, powdered magnesium oxide, chromium trioxide, clay or kaolin. 3. The magnesium aluminum spinel mass of claim 1 further comprising up to 6% by weight of inorganic binders such as phosphoric acid, sulfuric acid, hydrochloric acid, and salts thereof. 4. A magnesium-aluminum spinel mass according to claim 1, characterized in that it comprises up to 3% by weight of organic binders such as dextrin, starch, carboxymethylcellulose, sulphite liquor, methylcellulose, polyvinyl acetate dispersion, polyacrylate dispersion. 5. The magnesium-aluminum spinel mass according to claim 1, characterized in that it contains up to 5% 20% by weight of substances to increase the wettability angle of molten metals such as crystalline graphite, finely ground graphite, petroleum coke, metallurgical coke, silicon carbide with a grain size of up to 0.09 mm. 6. The magnesium-aluminum spinel mass of claim 1, wherein the bituminous clay composition comprises a tar-based binder such as a solution of tar and asphalt in organic solvents in an amount of up to 15% by weight.