RU2191223C1 - Lining of cathode casing of aluminum cell - Google Patents

Abstract

FIELD: non-ferrous metallurgy, namely constructions of cells for producing aluminum. SUBSTANCE: lining includes carbon blocks, two protective layers between which are arranged: refractory material layer and heat insulation layer. Lower protective layer consists of horizontally laid steel sheet placed between quartz-sand layers. Thickness of each layer of quartz sand is (10-15)mm; upper protective layer is also made of quartz sand. Such design allows to eliminate penetration of fluorides into heat insulation of lining. EFFECT: enhanced operational parameters, increased useful life period of cell. 3 cl, 1 dwg

Description

 The invention relates to the field of non-ferrous metallurgy, in particular to the design of electrolytic cells for producing aluminum.

 Known lining of the cathode casing of an aluminum electrolyzer containing coal blocks, refractory and heat-insulating layers with a red brick layer between them (ed. St. CCCP N 1571104).

 The disadvantage of this lining is the possibility of penetration of aluminum and electrolyte through cracks in the brick, which leads to a decrease in the life of the lining.

 Known lining of the cathode casing of an aluminum electrolyzer containing carbon blocks, refractory and heat-insulating layers and a protective layer located between them, made of nepheline (ed. St. USSR N 918335).

 Known lining of the cathode casing of an aluminum electrolyzer containing carbon blocks, refractory and heat-insulating layers and a protective layer made of a metal sheet (Japanese application N 58-161789, IPC C 25 C 3/08).

 The disadvantage of these linings is that. that these protective layers cannot provide reliable protection of thermal insulation from impregnation with fluorine salts throughout the campaign.

 Known lining of the cathode casing of an aluminum electrolyzer containing two protective layers (Hungarian patent N 154854).

 According to this patent, the cell lining has two protective layers, one of which is made of oxides and / or fluorides of Ca, Mg, Na, or mixtures thereof, and the second layer is made in the form of a metal sheet.

 The lining of the cathode casing of an aluminum electrolyzer according to the patent of the Russian Federation 2131487 is known. In a lining having carbon blocks and a heat-insulating layer, the upper protective layer consists of a mixture of alumina with aluminum fluoride or fresh cryolite, taken in the ratio 2: (0.75-0.9). The lower protective layer consists of two steel sheets laid horizontally one above the other with a gap of 1-3 mm filled with alumina, while a layer of refractory material is placed between the first and second protective layers. This patent is taken as a prototype.

 This solution increases the service life of the cell, but does not provide complete protection of the lining from the penetration of aluminum and fluorine salts into the insulating material, which degrades its quality and reduces the performance of the cell.

 The technical result of the invention is the elimination of fluorine salts in the heat-insulating lining, increasing the service life of the lining of the cathode casing and improving the performance of the cell.

 The technical result is achieved as follows.

 The lining of the cathode casing of an aluminum electrolyzer, including carbon blocks, two protective layers with a layer of refractory material between them and a heat-insulating layer, contains a lower protective layer made of horizontally laid steel sheet placed between layers of quartz sand.

 In the lower protective layer, the thickness of each layer of quartz sand is 10-15 mm.

 The upper protective layer is made of quartz sand.

 At operating temperatures of electrolysis, quartz sand turns into a glassy mass on both sides of the steel sheet, which provides reliable protection of the heat-insulating layer from the penetration of fluoride salts, while one steel sheet is enough to ensure a technical result.

 The drawing shows an example of the lining of the cathode casing of an aluminum electrolyzer.

 The lining consists of a side lining 1, a hearth made of carbon blocks 2, laid on the upper protective layer 3, consisting of quartz sand. Under the protective layer 3 is a layer of refractory material 4 made of fireclay brick. Below layer 4 there is a second - lower protective layer, consisting of a steel sheet 5, laid between layers of quartz sand 6 and 7.

 Below the second protective layer is a thermal insulation material 8 made of vermiculite. The space between the side lining 1 and the coal blocks 2 is filled with a hearth mass 9.

 The protective layer 3 has a thickness of 40 mm and is sealed with a roller or other method.

 The thickness of the steel sheet 5 is 1-2 mm. The sheet can be continuous or consist of separate sheets laid with a dressing of joints of 200-400 mm.

 The steel sheet can be made of heat-resistant steel, for example, grade 09G2S.

 The thickness of the layers of quartz sand, between which a steel sheet is placed, is 10-15 mm.

 An industrial inspection showed that the lining provides reliable protection of the insulating layer from the penetration of fluorine salts.

Claims (3)

 1. Lining of the cathode casing of an aluminum electrolyzer, including carbon blocks, two protective layers with a layer of refractory material placed between them and a heat-insulating layer, characterized in that the lower protective layer is made of horizontally laid steel sheet placed between layers of quartz sand.  2. The lining according to claim 1, characterized in that in the lower protective layer, the thickness of each layer of quartz sand is 10-15 mm  3. Lining according to claims 1 and 2, characterized in that the upper protective layer is made of quartz sand.