Lining for an aluminum electrolyzer having inert anodes

Abstract

The invention provides a lining for an aluminium electrolyzer having inert anodes and is enclosed in a cathode casing comprising a bottom formed from taller blocks having projections and shorter bottom blocks. The shorter bottom blocks are mounted at the ends of the bottom of the cathode device. The shorter bottom blocks alternate with the taller bottom blocks having projections. Vertical channels are provided in the projections of the blocks over the entire thickness of the block for the mounting of conductive elements formed from aluminium and are attached in the lower part to a current-carrying collector that is in the form of a plate which extends out of the ends of the bottom blocks and through the longitudinal sides of the cathode casing.

Claims

1. Lining of an aluminum electrolyzer with inert anodes, enclosed in a cathode casing, including a bottom made from refractory noncarbon material, and conductive elements of aluminum, which are liquid in the upper part in contact with the aluminum melt and solid in the lower part, and installed passing vertically through the bottom, characterized in that the bottom is made of taller bottom blocks having projections and shorter bottom blocks, the shorter bottom blocks being mounted at the end faces of the bottom, wherein the shorter bottom blocks alternate with the taller bottom blocks having projections, and vertical channels are provided only in the projections of the blocks over the entire thickness of the block for the mounting of the conductive elements, while the conductive elements are fastened in the lower part to a current-carrying collector in the form of a plate which extends horizontally out from the end faces of the bottom blocks and through the longitudinal sides of the cathode casing.

2. Lining of an aluminum electrolyzer according to claim 1, characterized in that the conductive elements are L-shaped or T-shaped.

3. Lining of an aluminum electrolyzer according to claim 1, characterized in that the bottom blocks are made of high-alumina concrete which is roasted up to 1200° C. or they are made of several layers, a working layer made of high-alumina concrete with thickness of 0.4 to 0.6 of the thickness of the block, and a secondary layer made of alumosilicate concrete, for the rest.

4. Lining of an aluminum electrolyzer according to claim 1, characterized in that the connection between the bottom blocks is made of high-alumina concrete with reduced viscosity or by means of an adhesive or cementing composition with a seam thickness of 5-20 mm.

Description

(1) FIG. 1 shows the proposed liner of an aluminum electrolyzer, shown with a quarter cut out;

(2) FIG. 2 shows a bottom block in assembled form, with a cut out;

(3) FIG. 3 shows conductive elements in assembled form with the current-carrying collector;

(4) FIG. 4 shows the lining of an aluminum electrolyzer with conductive elements of L-shape;

(5) FIG. 5 shows a bottom block with conductive elements of L-shape;

(6) FIG. 6 shows conductive elements of L-shape in assembled form with the current-carrying collector;

(7) FIG. 7 shows a bottom block with conductive elements of T-shape;

(8) FIG. 8 shows conductive elements of T-shape in assembled form with the current-carrying collector;

(9) FIG. 9 shows a bottom block in assembled form according to claim 6.

(10) The lining of an aluminum electrolyzer with inert anodes includes a steel cathode casing 1, taller bottom blocks with projections 2, shorter bottom blocks 3, conductive elements 5 of aluminum installed in channels 4 of the bottom blocks 2, with a liquid part 6, a current-carrying collector 7 of aluminum plate with a part 8 extending to the outside, seams 9 of high-alumina concrete between the blocks, edge blocks 10, layers of refractory brick, such as brick made from high-alumina, magnesia, periclase carbonaceous fire clay brick, and thermal insulating materials 11, which can be made from lightweight fire clay, vermiculite, foam diatomite, calcium silicate, and a secondary layer of the bottom block 12 made of alumosilicate concrete.

(11) In order to completely prevent instances of clogging of the channels with the conductive elements in the bottom with alumina, the conductive elements 5 are in an L or T shape, i.e., the upper part of the conductive element 6 is turned at a 90° angle with the channel exiting onto the lateral surface of the projection of the block 2 in the case of the L-shape. Or in the case of the T-shaped block, the upper part of the conductive element 6 splits in two and also emerges onto the lateral surfaces of the projection of the bottom block 2.

(12) For better filling of the seams between the bottom blocks, it is proposed to use a refractory high-alumina concrete with reduced viscosity, i.e., to use self-leveling concrete. After mixing with a small amount of water, it forms concrete which spreads and degasses without the use of vibration. It has all the benefits of low-cement concretes (low porosity, high density, strength, abrasion resistance, thermal resistance), and it forms a smooth mirror surface. The use of such concrete is advisable for the lining of hard to reach places, such as the seams between the blocks.

(13) To form a monolithic bottom of bottom blocks, one can glue them together. Such a method of joining reduces the area of the seams between blocks and ensures a monolithic bottom, which in turn reduces the likelihood of electrolyte leaking into the lining. For this, one can use an adhesive or cementing composition, the thickness of the seam will be 5-20 mm.

(14) Typically, blocks of refractory high-alumina concrete are roasted to a temperature of 900° C.; in the present instance, it is proposed to roast them to 1200° C. At this temperature, the process of sintering of the concrete components takes place, ceramic bonds are formed, and the concrete takes on its maximum strength. In this case, the bottom blocks have heightened resistance to the cryolite/alumina melt.

(15) In the event that the bottom blocks are made from several layers, a working layer of high-alumina concrete with a thickness of 0.4-0.6 of the thickness of the block, and a secondary layer made of alumosilicate concrete, when the working layer is impregnated with the electrolyte components the electrolyte will enter into the secondary layer and enter into a reaction, forming albite. This, in turn, will dissolve the metal fluorides and form a highly viscous glasslike silicate system, preventing further penetration of the electrolyte components.

(16) The lining of an aluminum electrolyzer with inert anodes is assembled as follows.

(17) The bottom of refractory high-alumina concrete, made of individual blocks which after being shaped go through stages of drying and roasting, is assembled in the space of 5-8 hours, the quality of the blocks being better than that of a monolithic bottom cast in situ.

(18) First of all the bottom blocks are assembled; for this, a previously connected current-carrying collector with conductive elements (vertical rods) is placed in the shaped bottom block and secured there, after which the bottom block is transported to the site of assembly of the lining.

(19) After assembly and installation of the steel cathode casing 1, its bottom is lined with refractory and thermal insulating materials 11, after which the surface of the refractory layer is covered with a layer of loose material, playing the role of a leveling cushion, on which the bottom blocks are set, with a certain spacing, so as to have a gap of 30-50 mm between adjacent blocks, in order to create the seam 9 between blocks. After this, the side lining or “brim” is laid, situated along the perimeter of the cathode casing between the bottom blocks and the lower part of the walls of the cathode casing and consisting of a layer of thermal insulating material, packed against the walls of the casing, and refractory material packed against the thermal insulating material. The projecting parts of the current-carrying collectors are clad with the lateral lining, ensuring tightness of the “brim” while at the same time not impeding the thermal expansion of the aluminum collectors. The “brim” is the base for installation of the edge lining. The installing of the edge blocks of nonmetallic refractory compounds is done in a single row along the walls of the casing 1, gluing them to the walls of the casing, and lubricating all of the bearing and joining surfaces. One can use as the adhesive or cementing composition gunite, mortar, or refractory concrete containing silicon carbide powder.

(20) The culminating and critical operation in the assembly of the lining is the filling of the seams between the bottom blocks.

(21) The proposed lining of an aluminum electrolyzer with inert anodes enables an assembly with less labor intensity, it improves the technical and economic indicators of the operation by lowering the expenditure of electricity, and it increase the operating reliability of the electrolyzer by preventing clogging of the channels with the conductive elements in the bottom.