SU953403A1 - Lining of reflection furnace for melting aluminium and its alloys - Google Patents

Description

The invention relates to non-ferrous metallurgy, namely to the linings of smelting reflective furnaces. The lining of the reflective furnace is well known, which includes the brickwork of a fireclay refractory and plastering. The coating on the basis of the oxide is made on the side of the melting space GT |. The disadvantage of such a lining is that the boron oxide forms fusible chemically unstable glasses. The mechanism for the destruction of such a coating is as follows. In the case of partial oxidation of an aluminum melt, its oxide appears, in the presence of which the number of VO tetrahedra three-dimensionally connected into a spatial grid decreases sharply, which leads to the separation of protective coating and subsequent destruction of it during the process of smelting metal. The exposed fireclay refractory in contact with the molten aluminum intensively interacts. On the surface of the lining are formed slag nastily composition: corundum, spinel MgO-Al2 Oo, cemented by metallic aluminum, silicon, iron. It is difficult to clean the bath. The melt is contaminated with non-metallic inclusions and silicon. Closest to the proposed technical essence and the achieved positive effect is the lining of the reflective furnace, which includes brick masonry from fireclay refractory materials and the bath lining of the melting furnace, made of corundum chemically resistant in aluminum melts 2. A weakness to the melt impregnation is known metal. This is explained by the fact that pressed and roasted corundum products have up to 80 effective pores of the total open porosity, which cause the penetration of the melt into the refractory. For example, if you take corundum brick after a month of service in a furnace hearth under an aluminum layer, its weight increases by 600 g, as the brick is impregnated with metal. 1 m of corundum masonry absorbs 100-120 kg of aluminum per year. At an area of 0 m inside the surface of a forty-titon bath of a reflective furnace, the loss is about 5 tons of metal. In addition, the deep impregnation of refractories with metal leads to an irreversible increase in thermal conductivity of the lining, increasing the unproductive energy expenditures to maintain the thermal regime of the unit, as well as reducing the refractory properties of the furnace. The object of the invention is to increase the metal resistance of the lining, which provides an increase in the service life of the lining. This goal is achieved by the fact that the lining of a reflective furnace for melting aluminum and its alloys, including refractory brickwork and lining of a melting bath with a material that is chemically resistant to molten aluminum, is made from heat-treated products with closed (dead-end) porosity, preferably asbestos-cement products. The advantage of such a lining is that the products with closed porosity are not impregnated with the molten metal, which contributes not only to the reduction of metal losses, but also to the reduction of chassis foot wear.

povki.

This increases the stability of the thermophysical properties of the lining, i saves energy consumption to maintain the required melting temperature, increases the service life of the thermal unit, i.e., increases the efficiency of the lining and the unit as a whole.

The drawing shows the plot of the lining of the wall of the melting bath.

The lining contains brickwork of fireclay refractory 1, in which from the side of the smelting prog / cm

1.75 12.5

MPa

12.0

MPa 3

sme. 03 openings are available 2 for fastening the studs 3- The studs 3c with the root end are plugged into the holes and fixed with a chamotte mortar. The ends of the studs are cut under the nut and are intended for fastening heat-treated asbestos cement products 5 with through-holes 6. The inner layer of asbestos-cement facing products is fastened with fireclay mortar to the main lining. The outer layer is fixed on the studs under the nut, which are closed with asbestos cement plugs 7- Asbestos cement plugs form a compensation gap with the end of the stud, providing for free thermal expansion of the stud. Asbestos-cement products that meet the requirements of GOST 248-78 are subjected to heat treatment at a temperature of 650 + 30 C. The temperature rise rate does not exceed 3 deg / min. The existence of the major changes occurring in the products is as follows. At a temperature of 420-500 ° C, the dehydration of calcium oxide hydrate occurs to form free calcium oxide, and at 600 ° C, the dehydration of mineral fiber and cement components occurs. In this case, some softening of the material occurs, but as can be seen from the table above, the products satisfy the necessary strength requirements. The table shows the properties of asbestos-cement products after heat treatment.

Claims (1)

Claim Lining of a reflective furnace for smelting aluminum and its alloys, including expansion at 900 ° C l / t 8.75χΐδ ^& Heat resistance (8 ° ° air) Heat us 5 Corrosion wear (at 800 C, 6 h exposure) ° / Ό Not Bench tests of metal resistance of heat-treated asbestos-cement products in the mode; 25 aluminum melts confirmed the absence of chemical interaction and impregnation. • Thus, the proposed lining of the reflective furnace is metal-resistant, which increases the duration of the brickwork from the refractory and the lining of the melting bath with material chemically resistant in aluminum melts, characterized in that in order to increase the service life of the lining by increasing the metal resistance lining, it is made of heat-treated products with a closed (dead end) porosity, preferably from asbestos-cement products.